Chapter 5: Approach to Cardiac Disease Diagnosis PDF

Universidad de Monterrey Access Provided by: Current Diagnosis & Treatment: Cardiology, 6e Chapter 5: Approach to Cardiac Disease Diagnosis Michael H. Crawford GENER...

Universidad de Monterrey Access Provided by: Current Diagnosis & Treatment: Cardiology, 6e Chapter 5: Approach to Cardiac Disease Diagnosis Michael H. Crawford GENERAL CONSIDERATIONS The patient’s history is a critical feature in the evaluation of suspected or overt heart disease. It includes information about the present illness, past illnesses, and the patient’s family. From this information, a chronology of the patient’s disease process should be constructed. Determining what information in the history is useful requires a detailed knowledge of the pathophysiology of cardiac disease. The effort spent on listening to the patient is time well invested because the cause of cardiac disease is often discernible from the history. A. Common Symptoms 1. Chest pain Chest pain is one of the cardinal symptoms (Table 5–1) of ischemic heart disease, but it can also occur with other forms of heart disease. The five characteristics of ischemic chest pain, or angina pectoris, are as follows: Anginal pain usually has a substernal location but may extend to the left or right chest, shoulders, neck, jaw, arms, epigastrium, and, occasionally, upper back. The pain is deep, visceral, and intense; it makes the patient pay attention, but is not excruciating. Many patients describe it as a pressurelike sensation or a tightness. The duration of the pain is minutes, not seconds. The pain tends to be precipitated by exercise or emotional stress. The pain is relieved by resting or taking sublingual nitroglycerin. Table 5–1. Common Symptoms of Potential Cardiac Origin Chest pain or pressure Dyspnea on exertion Paroxysmal nocturnal dyspnea Orthopnea Syncope or near syncope Transient neurologic defects Edema Palpitation Cough 2. Dyspnea A frequent complaint Downloaded 202517 of8:40 patients withIP A Your a variety is of cardiac diseases, dyspnea is ordinarily one of four types. The most common is exertional dyspnea, which usually Chapter means that 5: Approach the underlying to Cardiac Disease condition is mild Diagnosis, because Michael it requires the increased demand of exertion to precipitate symptoms. The H. Crawford next Page 1 / 16 ©2025 most McGrawis Hill. common All Rights paroxysmal Reserved. nocturnal Terms dyspnea, of Use Privacy characterized by thePolicy Notice patient Accessibility awakening after being asleep or recumbent for an hour or more. This symptom is caused by the redistribution of body fluids from the lower extremities into the vascular space and back to the heart, resulting in volume overload; it suggests a more severe condition. Third is orthopnea, a dyspnea that occurs immediately on assuming the recumbent position. The mild Cough Universidad de Monterrey Access Provided by: 2. Dyspnea A frequent complaint of patients with a variety of cardiac diseases, dyspnea is ordinarily one of four types. The most common is exertional dyspnea, which usually means that the underlying condition is mild because it requires the increased demand of exertion to precipitate symptoms. The next most common is paroxysmal nocturnal dyspnea, characterized by the patient awakening after being asleep or recumbent for an hour or more. This symptom is caused by the redistribution of body fluids from the lower extremities into the vascular space and back to the heart, resulting in volume overload; it suggests a more severe condition. Third is orthopnea, a dyspnea that occurs immediately on assuming the recumbent position. The mild increase in venous return (caused by lying down) before any fluid is mobilized from interstitial spaces in the lower extremities is responsible for the symptom, which suggests even more severe disease. Finally, dyspnea at rest suggests severe cardiac disease. Dyspnea is not specific for heart disease, however. Exertional dyspnea, for example, can be due to pulmonary disease, anemia, or deconditioning. Orthopnea is a frequent complaint in patients with chronic obstructive pulmonary disease and postnasal drip. A history of “twopillow orthopnea” is of little value unless the reason for the use of two pillows is discerned. Resting dyspnea is also a sign of pulmonary disease. Paroxysmal nocturnal dyspnea is perhaps the most specific for cardiac disease because few other conditions cause this symptom. 3. Syncope and presyncope Lightheadedness, dizziness, presyncope, and syncope are important indications of a reduction in cerebral blood flow. These symptoms are nonspecific and can be due to primary central nervous system disease, metabolic conditions, dehydration, or innerear problems. Because bradyarrhythmias and tachyarrhythmias are important cardiac causes, a history of palpitations preceding the event is significant. 4. Transient central nervous system deficits Deficits such as transient ischemic attacks (TIAs) suggest emboli from the heart or great vessels or, rarely, from the venous circulation through an intracardiac shunt. A TIA should prompt the search for cardiovascular disease. Any sudden loss of blood flow to a limb also suggests a cardioembolic event. 5. Fluid retention These symptoms are not specific for heart disease but may be due to reduced cardiac function. Typical symptoms are peripheral edema, bloating, weight gain, and abdominal pain from an enlarged liver or spleen. Decreased appetite, diarrhea, jaundice, and nausea and vomiting can also occur from gut and hepatic dysfunction due to fluid engorgement. 6. Palpitation Normal resting cardiac activity usually cannot be appreciated by the individual. Awareness of heart activity is often referred to by patients as palpitation. Among patients, there is no standard definition for the type of sensation represented by palpitation, so the physician must explore the sensation further with the patient. It is frequently useful to have the patient tap the perceived heartbeat out by hand. Commonly, unusually forceful heart activity at a normal rate (60–100 bpm) is perceived as palpitation. More forceful contractions are usually the result of endogenous catecholamine excretion that does not elevate the heart rate out of the normal range. A common cause of this phenomenon is anxiety. Another common sensation is that of the heart stopping transiently or of the occurrence of isolated forceful beats or both. This sensation is usually caused by premature ventricular contractions, and the patient either feels the compensatory pause or the resultant more forceful subsequent beat or both. Occasionally, the individual refers to this phenomenon as “skipped” beats. The least common sensation reported by individuals, but the one most linked to the term “palpitation” is rapid heart rate that may be regular or irregular and is usually supraventricular in origin. 7. Cough Although cough is usually associated with pulmonary disease processes, cardiac conditions that lead to pulmonary abnormalities may be the root cause of the cough. A cardiac cough is usually dry or nonproductive. Pulmonary fluid engorgement from conditions such as heart failure may present as cough. Pulmonary hypertension from any cause can result in cough. Finally, angiotensinconverting enzyme inhibitors, which are frequently used in cardiac conditions, can cause cough. B. History 1. The present illness Downloaded 202517 8:40 A Your IP is Chapter 5: Approach to Cardiac Disease Diagnosis, Michael H. Crawford Page 2 / 16 This ©2025is aMcGraw chronology Hill.ofAllthe events Rights leading upTerms Reserved. to the patient’s current Policy of Use Privacy complaints. Usually, Notice physicians start with the chief complaint and explore the Accessibility patient’s symptoms. It is especially important to determine the frequency, intensity, severity, and duration of all symptoms; their precipitating causes; what relieves them; and what aggravates them. Although information about previous related diseases and opinions from other physicians are often as cough. Pulmonary hypertension from any cause can result in cough. Finally, angiotensinconverting enzyme inhibitors, which are frequently used in Universidad de Monterrey cardiac conditions, can cause cough. Access Provided by: B. History 1. The present illness This is a chronology of the events leading up to the patient’s current complaints. Usually, physicians start with the chief complaint and explore the patient’s symptoms. It is especially important to determine the frequency, intensity, severity, and duration of all symptoms; their precipitating causes; what relieves them; and what aggravates them. Although information about previous related diseases and opinions from other physicians are often valuable, it is essential to explore the basis of any prior diagnosis and ask the patient about objective testing and the results of such testing. A history of prior treatment is often revealing because medications or surgery may indicate the nature of the original problem. A list of all the patient’s current medications should be reviewed, confirming the dosages, the frequency of administration, and whether they are helping the patient, and noting any side effects. 2. Antecedent conditions Several systemic diseases may have cardiac involvement. It is therefore useful to search for a history of rheumatic fever, which may manifest as Sydenham chorea, joint pain and swelling, or merely frequent sore throats. Other important diseases that affect the heart include metastatic cancer, thyroid disorders, diabetes mellitus, and inflammatory diseases such as rheumatoid arthritis and systemic lupus erythematosus. Certain events during childhood are suggestive of congenital or acquired heart disease; these include a history of cyanosis, reduced exercise tolerance, or long periods of restricted activities or school absence. Exposure to toxins, infectious agents, and other noxious substances may also be relevant. In addition, blunt chest trauma and radiation therapy can injure the heart and vasculature. 3. Atherosclerotic risk factors Atherosclerotic cardiovascular disease is the most common form of heart disease in industrialized nations. The presenting symptoms of this ubiquitous disorder may be unimpressive and minimal, or as impressive as sudden death. It is therefore important to determine from the history whether any risk factors for this disease are present. The most important is a family history of atherosclerotic disease, especially at a young age; diabetes mellitus; lipid disorders such as a high lowdensity lipoprotein cholesterol level; hypertension; and smoking. Less important factors include a lack of exercise, high stress levels, lower socioeconomic status, and truncal obesity. There are formulae available online to calculate the risk of a cardiovascular event based on some of these factors. 4. Family history A family history is important for determining the risk for not only atherosclerotic cardiovascular disease, but also for many other cardiac diseases. Congenital heart disease, for example, is more common in the offspring of parents with this condition, and a history of the disorder in the antecedent family or siblings is significant. Other genetic diseases, such as neuromuscular disorders or connective tissue disorders (eg, Marfan syndrome), can affect the heart. Acquired diseases, such as rheumatic valve disease, can cluster in families because of the spread of the streptococcal infection among family members. The lack of a history of hypertension in the family might prompt a more intensive search for a secondary cause. A history of atherosclerotic disease sequelae, such as limb loss, strokes, and heart attacks, may provide a clue to the aggressiveness of an atherosclerotic tendency in a particular family group. PHYSICAL FINDINGS A. Physical Examination The physical examination is less important than the history in patients with ischemic heart disease, but it is of critical value in patients with congenital and valvular heart disease. In the latter two categories, the physician can often make specific anatomic and etiologic diagnoses based on the physical examination. Certain abnormal murmurs and heart sounds are specific for structural abnormalities of the heart. The physical examination is also important for confirming the diagnosis and establishing the severity of heart failure, and it is the only way to diagnose systemic hypertension because this diagnosis is based on elevated blood pressure recordings. 1. Blood pressure Proper measurement of the systemic arterial pressure by cuff sphygmomanometry is one of the keystones of the cardiovascular physical examination. It is recommended that the brachial artery be palpated, and the diaphragm of the stethoscope be placed over it, rather than merely Downloaded 202517 8:40 sticking the stethoscope A antecubital in the Your IP is fossa. Current methodologic standards dictate that the onset and disappearance of the Korotkoff sounds Chapter 5: Approach to Cardiac Disease Diagnosis, Michael H. Crawford Page 3 / 16 define ©2025the systolic McGraw and Hill. Alldiastolic pressures, respectively. Rights Reserved. Terms of Use Although this Privacy is the best Policy approach Notice in most cases, there are exceptions. For example, in patients Accessibility in whom the diastolic pressure drops to near zero, the point of muffling of the sounds is usually recorded as the diastolic pressure. Because the diagnosis of systemic hypertension involves repeated measures under the same conditions, the operator should measure blood pressure under the this diagnosis is based on elevated blood pressure recordings. Universidad de Monterrey Access Provided by: 1. Blood pressure Proper measurement of the systemic arterial pressure by cuff sphygmomanometry is one of the keystones of the cardiovascular physical examination. It is recommended that the brachial artery be palpated, and the diaphragm of the stethoscope be placed over it, rather than merely sticking the stethoscope in the antecubital fossa. Current methodologic standards dictate that the onset and disappearance of the Korotkoff sounds define the systolic and diastolic pressures, respectively. Although this is the best approach in most cases, there are exceptions. For example, in patients in whom the diastolic pressure drops to near zero, the point of muffling of the sounds is usually recorded as the diastolic pressure. Because the diagnosis of systemic hypertension involves repeated measures under the same conditions, the operator should measure blood pressure under the same standard conditions each time. It is recommended that the patient be seated with their arm supported at heart level for 5 minutes before the pressure is measured. Orthostatic changes in blood pressure are a very important physical finding, especially in patients complaining of transient central nervous system symptoms, weakness, or unstable gait. The technique involves having the patient assume the upright position for at least 90 seconds before taking the pressure to be sure that the maximum orthostatic effect is measured. Although measuring the pressure in other extremities may be of value in certain vascular diseases, it provides little information in a routine examination beyond palpating pulses in all the extremities. Keep in mind, in general, that the pulse pressure (the difference between systolic and diastolic blood pressures) is a crude measure of left ventricular stroke volume. A widened pulse pressure suggests that the stroke volume is large; a narrowed pressure suggests that the stroke volume is small. 2. Peripheral pulses When examining the peripheral pulses, the physician is really conducting three examinations. The first is an examination of the cardiac rate and rhythm, the second is an assessment of the characteristics of the pulse as a reflection of cardiac activity, and the third is an assessment of the adequacy of the arterial conduit being examined. The pulse rate and rhythm are usually determined in a convenient peripheral artery, such as the radial. If a pulse is irregular, it is better to auscultate the heart; some cardiac contractions during rhythm disturbances do not generate a stroke volume sufficient to cause a palpable peripheral pulse. In many ways, the heart rate reflects the health of the circulatory system. A rapid pulse suggests increased catecholamine levels, which may be due to cardiac disease, such as heart failure; a slow pulse represents an excess of vagal tone, which may be due to disease or athletic training. To assess the characteristics of the cardiac contraction through the pulse, it is usually best to select an artery close to the heart, such as the carotid. Bounding highamplitude carotid pulses suggest an increase in stroke volume and should be accompanied by a wide pulse pressure on the blood pressure measurement. A weak carotid pulse suggests a reduced stroke volume. Usually, the strength of the pulse is graded on a scale of 1–4, where 2 is a normal pulse amplitude, 3–4 is a hyperdynamic pulse, and 1 is a weak pulse. A lowamplitude, slowrising pulse, which may be associated with a palpable vibration (thrill), suggests aortic stenosis. A bifid pulse (beating twice in systole) can be a sign of hypertrophic obstructive cardiomyopathy, severe aortic regurgitation, or the combination of moderately severe aortic stenosis and regurgitation. A dicrotic pulse (an exaggerated, early, diastolic wave) is found in severe heart failure. Pulsus alternans (alternate strong and weak pulses) is also a sign of severe heart failure. When evaluating the adequacy of the arterial conduits, all palpable pulses can be assessed and graded on a scale of 0–4, where 4 is a fully normal conduit, and anything below that is reduced, including 0, which indicates an absent pulse. The major pulses routinely palpated on physical examination are the radial, brachial, carotid, abdominal aorta, femoral, dorsalis pedis, and posterior tibial. In special situations, the ulnar, subclavian, popliteal, axillary, temporal, and intercostal arteries are palpated. In assessing the abdominal aorta, it is important to make a note of the width of the aorta because an increase suggests an abdominal aortic aneurysm. It is particularly important to palpate the abdominal aorta in older individuals because abdominal aortic aneurysms are more prevalent in those older than 70. An audible bruit is a clue to significantly obstructed large arteries. During a routine examination, bruits are sought with the stethoscope head placed over the carotids, abdominal aorta, and femorals at the groin. Other arteries may be auscultated under special circumstances, such as suspected renal artery stenosis (flank bruit). 3. Jugular venous pulse Assessment of the jugular venous pulse can provide information about the central venous pressure and rightheart function. Examination of the right internal jugular vein is ideal for assessing central venous pressure because it is attached directly to the superior vena cava without intervening valves. The patient is positioned in the semiupright posture that permits visualization of the top of the right internal jugular venous blood column. The height of this column of blood, vertically from the sternal angle, is added to 5 cm of blood (the presumed distance to the center of the right atrium from the sternal angle) to obtain an estimate of central venous pressure in centimeters of blood. This can be converted to millimeters of mercury (mm Hg) with the formula: mm Hg = cm blood × 0.736 Downloaded 202517 8:40 A Your IP is Chapter Examining5:the Approach to Cardiac characteristics Disease of the Diagnosis, right internal Michael jugular pulse H. Crawford is valuable for assessing rightheart function and rhythm disturbances. ThePage 4 / 16 normal ©2025 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility jugular venous pulse has two distinct waves: a and v; the former coincides with atrial contraction and the latter with late ventricular systole. An absent a wave and an irregular pulse suggest atrial fibrillation. A large and early v wave suggests tricuspid regurgitation. The dips after the a and v waves are the of this column of blood, vertically from the sternal angle, is added to 5 cm of blood (the presumed distance to the center of the right atrium from the Universidad de Monterrey sternal angle) to obtain an estimate of central venous pressure in centimeters of blood. This can be converted to millimeters of mercury (mm Hg) with Access Provided by: the formula: mm Hg = cm blood × 0.736 Examining the characteristics of the right internal jugular pulse is valuable for assessing rightheart function and rhythm disturbances. The normal jugular venous pulse has two distinct waves: a and v; the former coincides with atrial contraction and the latter with late ventricular systole. An absent a wave and an irregular pulse suggest atrial fibrillation. A large and early v wave suggests tricuspid regurgitation. The dips after the a and v waves are the x and y descents; the former coincide with atrial relaxation and the latter with early ventricular filling. In tricuspid stenosis, the y descent is prolonged. Other applications of the jugular pulse examination are discussed in the chapters dealing with specific disorders. 4. Lungs Evaluation of the lungs is an important part of the physical examination. Diseases of the lung can affect the heart, just as diseases of the heart can affect the lungs. The major finding of importance is crackles at the pulmonary bases, indicating alveolar fluid collection. Although this is a significant finding in patients with congestive heart failure, it is not always possible to distinguish crackles caused by heart failure from those caused by pulmonary disease. The presence of pleural fluid, although useful in the diagnosis of heart failure, can be due to other causes. Heart failure most commonly causes a right pleural effusion; it can cause effusions on both sides but is least likely to cause isolated left pleural effusion. The specific constellation of dullness at the left base with bronchial breath sounds suggests an increase in heart size from pericardial effusion (Ewart sign) or another cause of cardiac enlargement; it is thought to be due to compression by the heart of a left lower lobe bronchus. When rightheart failure develops or venous return is restricted from entering the heart, venous pressure in the abdomen increases, leading to hepatosplenomegaly and eventually ascites. None of these physical findings is specific for heart disease; they do, however, help establish the diagnosis. Heart failure also leads to generalized fluid retention, usually manifested as lower extremity edema or, in severe heart failure, anasarca. 5. Cardiac auscultation Heart sounds are caused by the acceleration and deceleration of blood and the subsequent vibration of the cardiac structures during the phases of the cardiac cycle. To hear cardiac sounds, use a stethoscope with a bell and a taut diaphragm. Lowfrequency sounds are associated with ventricular filling and are heard best with the bell. Mediumfrequency sounds are associated with valve opening and closing; they are heard best with the diaphragm. Cardiac murmurs are due to turbulent blood flow, are usually high to medium frequency, and are heard best with the diaphragm. However, low frequency atrioventricular valve inflow murmurs, such as that produced by mitral stenosis, are best heard with the bell. Auscultation should take place in areas that correspond to the location of the heart and great vessels. Such placement will, of course, need to be modified for patients with unusual body habitus or an unusual cardiac position. When no cardiac sounds can be heard over the precordium, they can often be heard in either the subxiphoid area or the right supraclavicular area. Auscultation in various positions is recommended because lowfrequency filling sounds are best heard with the patient in the left lateral decubitus position, and highfrequency murmurs, such as that of aortic regurgitation, are best heard with the patient sitting. A. HEART SOUNDS The first heart sound is coincident with mitral and tricuspid valve closure and has two components in up to 40% of normal individuals. There is little change in the intensity of this sound with respiration or position. The major determinant of the intensity of the first heart sound is the electrocardiographic (ECG) PR interval, which determines the time delay between atrial and ventricular contraction and thus the position of the mitral valve when ventricular systole begins. With a short PR interval, the mitral valve is widely open when systole begins, and its closure increases the intensity of the first sound, as compared to a long PRinterval beat when the valve partially closes prior to the onset of ventricular systole. Certain disease states, such as mitral stenosis, also can increase the intensity of the first sound. The second heart sound is coincident with closure of the aortic and pulmonic valves. Normally, this sound is single in expiration and split during inspiration, permitting the aortic and pulmonic components to be distinguished. The inspiratory split is due to a delay in the occurrence of the pulmonic component because of a decrease in pulmonary vascular resistance, which prolongs pulmonary flow beyond the end of right ventricular systole. Variations in this normal splitting of the second heart sound are useful in determining certain disease states. For example, in atrial septal defect, the second sound is usually split throughout the respiratory cycle because of the constant increase in pulmonary flow. In patients with left bundle branch block, a delay occurs in the aortic component of the second heart sound, which results in reversed respiratory splitting; single with inspiration, split with expiration. Downloaded A third heart202517 8:40 Aduring sound occurs Your early IP is rapid filling of the left ventricle; it can be produced by any condition that causes left ventricular volume Chapter 5: Approach to Cardiac Disease Diagnosis, overload or dilatation. Therefore, it can be heard in suchMichael H. Crawford disparate Page 5 / 16 conditions as congestive heart failure and normal pregnancy. A fourth heart ©2025 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility sound is due to a vigorous atrial contraction into a stiffened left ventricle and can be heard in left ventricular hypertrophy of any cause or in diseases that reduce compliance of the left ventricle, such as myocardial infarction. pulmonic component because of a decrease in pulmonary vascular resistance, which prolongs pulmonary flow beyond the end of right ventricular systole. Variations in this normal splitting of the second heart sound are useful in determining certain disease states. For example, in atrialde Universidad septal Monterrey defect, the second sound is usually split throughout the respiratory cycle because of the constant increase in pulmonary flow.Access In patients with left Provided by: bundle branch block, a delay occurs in the aortic component of the second heart sound, which results in reversed respiratory splitting; single with inspiration, split with expiration. A third heart sound occurs during early rapid filling of the left ventricle; it can be produced by any condition that causes left ventricular volume overload or dilatation. Therefore, it can be heard in such disparate conditions as congestive heart failure and normal pregnancy. A fourth heart sound is due to a vigorous atrial contraction into a stiffened left ventricle and can be heard in left ventricular hypertrophy of any cause or in diseases that reduce compliance of the left ventricle, such as myocardial infarction. Although third and fourth heart sounds can occasionally occur in normal individuals, all other extra sounds are signs of cardiac disease. Early ejection sounds are due to abnormalities of the semilunar valves, from restriction of their motion, thickening, or both (eg, a bicuspid aortic valve, pulmonic or aortic stenosis). A midsystolic click is often due to mitral valve prolapse and is caused by sudden tensing in midsystole of the redundant prolapsing segment of the mitral leaflet. The opening of a thickened atrioventricular valve leaflet, as in mitral stenosis, will cause a loud opening sound (snap) in early diastole. A lower frequency (more of a knock) sound at the time of rapid filling may be an indication of constrictive pericarditis. These early diastolic sounds must be distinguished from a third heart sound. B. MURMURS Systolic murmurs are very common and do not always imply cardiac disease. They are usually rated on a scale of 1 to 6, where grade 1 is barely audible, grade 4 is associated with palpable vibrations (thrill), grade 5 can be heard with the edge of the stethoscope, and grade 6 can be heard without a stethoscope. Most murmurs fall in the 1–3 range, and murmurs in the 4–6 range are almost always due to pathologic conditions; severe disease can exist with grades 1–3 or no cardiac murmurs, however. The most common systolic murmur is the crescendo/decrescendo murmur that increases in intensity as blood flows early in systole and diminishes in intensity through the second half of systole. This murmur can be due to vigorous flow in a normal heart or to obstructions in flow, as occurs with aortic stenosis, pulmonic stenosis, or hypertrophic cardiomyopathy. The socalled innocent flow murmurs are usually grades 1–2 and occur very early in systole; they may have a vibratory quality and are usually less apparent when the patient is in the sitting position (when venous return is less). If an ejection sound is heard, there is usually some abnormality of the semilunar valves. Although louder murmurs may be due to pathologic cardiac conditions, this is not always so. Distinguishing benign from pathologic systolic flow murmurs is one of the major challenges of clinical cardiology. Benign flow murmurs can be heard in 80% of children; the incidence declines with age but may be prominent during pregnancy or in adults who are thin or physically well trained. The murmur is usually benign in a patient with a softflow murmur that diminishes in intensity in the sitting position and neither a history of cardiovascular disease nor other cardiac findings. The holosystolic, or pansystolic, murmur is almost always associated with cardiac pathology. The most common cause of this murmur is atrioventricular valve regurgitation, but it can also be observed in conditions such as ventricular septal defect, in which an abnormal communication exists between two chambers of markedly different systolic pressures. Although it is relatively easy to determine that these murmurs represent an abnormality, it is more of a challenge to determine their origins. Keep in mind that such conditions as mitral regurgitation, which usually produce holosystolic murmurs, may produce crescendo/decrescendo murmurs, adding to the difficulty in differentiating benign from pathologic systolic flow murmurs. Diastolic murmurs are always abnormal and are usually graded on a 1 to 4 scale. The most frequently heard diastolic murmur is the highfrequency decrescendo early diastolic murmur of aortic regurgitation. This is usually heard best at the upper left sternal border or in the aortic area (upper right sternal border) and may radiate to the lower left sternal border and the apex. This murmur is usually very high frequency and may be difficult to hear. Although the murmur of pulmonic regurgitation may sound like that of aortic regurgitation when pulmonary artery pressures are high, if structural disease of the valve is present with normal pulmonary pressures, the murmur usually has a midrange frequency and begins with a slight delay after the pulmonic second heart sound. Pulmonic regurgitation is usually best heard in the pulmonic area (left second intercostal space parasternally). Mitral stenosis produces a lowfrequency rumbling diastolic murmur that is decrescendo in early diastole, but may become crescendo up to the first heart sound with moderately severe mitral stenosis and sinus rhythm. The murmur is best heard at the apex in the left lateral decubitus position with the bell of the stethoscope. Similar findings are heard in tricuspid stenosis, but the murmur is loudest at the lower left sternal border. A continuous murmur implies a connection between a high and a lowpressure chamber throughout the cardiac cycle, such as occurs with a fistula between the aorta and the pulmonary artery. If the connection is a patent ductus arteriosus, the murmur is heard best under the left clavicle; it has a machinelike quality. Continuous murmurs must be distinguished from the combination of systolic and diastolic murmurs in patients with combined lesions (eg, aortic stenosis and regurgitation). Traditionally, the origin of heart murmurs was based on five factors: (1) their timing in the cardiac cycle, (2) where on the chest they were heard, (3) their characteristics, (4) their intensity, and (5) their duration. Unfortunately, this traditional classification system is unreliable in predicting the underlying pathology. A more accurate method, dynamic auscultation, changes the intensity, duration, and characteristics of the murmur by Downloaded 202517 8:40 A Your IP is bedside maneuvers Chapter 5: Approachthat to alter hemodynamics. Cardiac Disease Diagnosis, Michael H. Crawford Page 6 / 16 ©2025 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility The simplest of these maneuvers is observation of any changes in murmur intensity with normal respiration because all rightsided cardiac murmurs should increase in intensity with normal inspiration. Although some exceptions exist, the method is very reliable for detecting such murmurs. machinelike quality. Continuous murmurs must be distinguished from the combination of systolic and diastolic murmurs in patients with combined Universidad de Monterrey lesions (eg, aortic stenosis and regurgitation). Access Provided by: Traditionally, the origin of heart murmurs was based on five factors: (1) their timing in the cardiac cycle, (2) where on the chest they were heard, (3) their characteristics, (4) their intensity, and (5) their duration. Unfortunately, this traditional classification system is unreliable in predicting the underlying pathology. A more accurate method, dynamic auscultation, changes the intensity, duration, and characteristics of the murmur by bedside maneuvers that alter hemodynamics. The simplest of these maneuvers is observation of any changes in murmur intensity with normal respiration because all rightsided cardiac murmurs should increase in intensity with normal inspiration. Although some exceptions exist, the method is very reliable for detecting such murmurs. Inspiration is associated with reductions in intrathoracic pressure that increase venous return from the abdomen and the head, leading to an increased flow through the right heart chambers. The consequent increase in pressure increases the intensity of rightsided murmurs. These changes are best observed in the sitting position, where venous return is smallest, and changes in intrathoracic pressure can produce their greatest effect on venous return. In a patient in the supine position, when venous return is near maximum, there may be little change observed with respiration. The ejection sound caused by pulmonic stenosis does not routinely increase in intensity with inspiration. The increased blood in the right heart accentuates atrial contraction, which increases late diastolic pressure in the right ventricle, partially opening the stenotic pulmonary valve and thus diminishing the opening sound of this valve with the subsequent systole. Changes in position are an important part of normal auscultation; they can also be of great value in determining the origin of cardiac murmurs (Table 5–2). Murmurs dependent on venous return, such as innocent flow murmurs, are softer or absent in upright positions; others, such as the murmur associated with hypertrophic obstructive cardiomyopathy, are accentuated by reduced left ventricular volume associated with the upright position. In physically capable individuals, a rapid squat from the standing position is often diagnostically valuable because it suddenly increases venous return and left ventricular volume and accentuates flow murmurs but diminishes the murmur of hypertrophic obstructive cardiomyopathy. The standsquat maneuver is also useful for altering the timing of the midsystolic click caused by mitral valve prolapse during systole. When the ventricle is small during standing, the prolapse occurs earlier in systole, moving the midsystolic click to early systole. During squatting, the ventricle dilates and the prolapse is delayed in systole, resulting in a late midsystolic click. Table 5–2. Differentiation of Systolic Murmurs Based on Changes in Their Intensity from Physiologic Maneuvers Origin of Murmur Maneuver Flow TR AS MR/VSD MVP HOCM Inspiration − or ↑ ↑ − − − − Stand ↓ − − − ↑ ↑ Squat ↑ − − − ↓ ↓ Valsalva ↓ ↓ ↓ ↓ ↑ ↑ Handgrip/TAO ↓ − − ↑ ↑ ↓ Post–PVC ↑ − ↑ − − ↑ AS, aortic stenosis; Flow, innocent flow murmur; HOCM, hypertrophic obstructive cardiomyopathy; MR, mitral regurgitation; MVP, mitral valve prolapse; PVC, premature ventricular contraction; TAO, transient arterial occlusion; TR, tricuspid regurgitation; VSD, ventricular septal defect; ↑ or ↓, change in intensity of murmur; −, no consistent change The Valsalva maneuver is also frequently used. The patient bears down and expires against a closed glottis, increasing intrathoracic pressure and markedly reducing venous return to the heart. Although almost all cardiac murmurs decrease in intensity during this maneuver, there are two exceptions: (1) The murmur of hypertrophic obstructive cardiomyopathy may become louder because of the diminished left ventricular volume and (2) The murmur associated with mitral regurgitation from mitral valve prolapse may become longer and louder because of the earlier occurrence of prolapse during systole. When the maneuver is very vigorous and prolonged, even these two murmurs may eventually diminish in intensity. Therefore, the Valsalva maneuver should be held for only about 10 seconds, so as not to cause prolonged diminution of the cerebral and coronary blood flow. Downloaded 202517 8:40 A Your IP is Chapter Isometric5: hand Approach gripto Cardiac Disease exercises have beenDiagnosis, Michaelarterial used to increase H. Crawford Page 7 / 16 and left ventricular pressure. These maneuvers increase the flow gradient for ©2025 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility mitral regurgitation, ventricular septal defect, and aortic regurgitation; the murmurs should then increase in intensity. Increasing arterial and left ventricular pressure increases left ventricular volume, thereby decreasing the murmur of hypertrophic obstructive cardiomyopathy. The Valsalva maneuver is also frequently used. The patient bears down and expires against a closed glottis, increasing intrathoracic pressure and Universidad markedly reducing venous return to the heart. Although almost all cardiac murmurs decrease in intensity during this maneuver, there are de twoMonterrey exceptions: (1) The murmur of hypertrophic obstructive cardiomyopathy may become louder because of the diminished left ventricular Access Providedvolume by: and (2) The murmur associated with mitral regurgitation from mitral valve prolapse may become longer and louder because of the earlier occurrence of prolapse during systole. When the maneuver is very vigorous and prolonged, even these two murmurs may eventually diminish in intensity. Therefore, the Valsalva maneuver should be held for only about 10 seconds, so as not to cause prolonged diminution of the cerebral and coronary blood flow. Isometric hand grip exercises have been used to increase arterial and left ventricular pressure. These maneuvers increase the flow gradient for mitral regurgitation, ventricular septal defect, and aortic regurgitation; the murmurs should then increase in intensity. Increasing arterial and left ventricular pressure increases left ventricular volume, thereby decreasing the murmur of hypertrophic obstructive cardiomyopathy. Noting the changes in murmur intensity in the heartbeat following a premature ventricular contraction, and comparing these to a beat that does not, can be extremely useful. The premature ventricular contraction interrupts the cardiac cycle, and during the subsequent compensatory pause, an extra long diastole occurs, leading to increased left ventricular filling. Therefore, murmurs caused by the flow of blood out of the left ventricle (eg, aortic stenosis) increase in intensity. There is usually no change in the intensity of the murmur of typical mitral regurgitation because blood pressure falls during the long pause and increases the gradient between the left ventricle and the aorta, allowing more forward flow. This results in the same amount of mitral regurgitant flow as on a normal beat with a higher aortic pressure and less forward flow. The increased volume during the long pause goes out of the aorta rather than back into the left atrium. Also, some of the increased blood volume in the left ventricle moves into the left atrium during isometric contraction before the aortic valve opens but does not change murmur intensity significantly. Unfortunately, there is no reliable way of inducing a premature ventricular contraction in most patients; it is fortuitous when a physician is present for one. Atrial fibrillation with markedly varying cycle lengths produces the same phenomenon and can be very helpful in determining the origin of murmurs. Marbach JA, Almufleh A, Santo PD, et al. Comparative accuracy of focused cardiac ultrasonography and clinical examination for left ventricular dysfunction and valvular heart disease: a systematic review and metaanalysis. Ann Intern Med. 2019;171:264–272. [PubMed: 31382273] Qaseem A, Ikobaltzeta IE, Mustafa RA, et al. Appropriate use of pointofcare ultrasonography in patients with acute dyspnea in emergency department or inpatient settings: a clinical guideline from the American College of Physicians. Ann Intern Med. 2021;174:985–993. [PubMed: 33900792] B. Diagnostic Studies 1. Electrocardiography ECG is perhaps the least expensive of all cardiac diagnostic tests, providing considerable value for the money. Modern ECGreading computers do an excellent job of measuring the various intervals between waveforms and calculating the heart rate and the left ventricular axis. These programs fall short, however, when it comes to diagnosing complex ECG patterns and rhythm disturbances, and the test results must be read by a physician skilled at ECG interpretation. Analysis of cardiac rhythm is perhaps the ECG’s most widely used feature; it is used to clarify the mechanism of an irregular heart rhythm detected on physical examination or that of an extremely rapid or slow rhythm. The ECG is also used to monitor cardiac rate and rhythm; ambulatory ECG monitoring devices allow assessment of cardiac rate and rhythm on an ambulatory basis. ECG radio telemetry is also often used on hospital wards and between ambulances and emergency departments to assess and monitor rhythm disturbances. There are two types of ambulatory ECG recorders: continuous recorders that record all heart beats over 1–21 days and intermittent recorders that can be attached to the patient or implanted subcutaneously for weeks or months and then activated to provide brief recordings of infrequent events. In addition to analysis of cardiac rhythm, ambulatory ECG recordings can be used to detect STwave transients indicative of myocardial ischemia and certain electrophysiologic parameters of diagnostic and prognostic value. The most common use of ambulatory ECG monitoring is the evaluation of symptoms such as syncope, nearsyncope, or palpitation for which there is no obvious cause, but cardiac rhythm disturbances are suspected. The ECG is an important tool for rapidly assessing metabolic and toxic disorders of the heart. Characteristic changes in the STT waves indicate imbalances of potassium and calcium. Drugs such as tricyclic antidepressants have characteristic effects on the QT and QRS intervals at toxic levels. Such observations on the ECG can be lifesaving in emergency situations with comatose patients or cardiac arrest victims. Chamber enlargement can be assessed through the characteristic changes of left or right ventricular and atrial enlargement. Evidence of chamber enlargement on the ECG usually signifies an advanced stage of disease with a poorer prognosis than that of patients with the same disease but no discernible enlargement. Downloaded 202517 8:40 A Your IP is Chapter 5:an The ECG is Approach to tool important Cardiac Diseasesuspected in managing Diagnosis, Michael acute H. Crawford coronary Page 8 / 16 syndromes. In patients with chest pain that is compatible with myocardial ©2025 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility ischemia, the characteristic STT–wave elevations that do not resolve with nitroglycerin (and are unlikely to be the result of an old infarction) become the basis for thrombolytic therapy or a primary percutaneous intervention. Rapid resolution of the ECG changes of myocardial infarction after imbalances of potassium and calcium. Drugs such as tricyclic antidepressants have characteristic effects on the QT and QRS intervals at toxic levels. Universidad de Monterrey Such observations on the ECG can be lifesaving in emergency situations with comatose patients or cardiac arrest victims. Access Provided by: Chamber enlargement can be assessed through the characteristic changes of left or right ventricular and atrial enlargement. Evidence of chamber enlargement on the ECG usually signifies an advanced stage of disease with a poorer prognosis than that of patients with the same disease but no discernible enlargement. The ECG is an important tool in managing suspected acute coronary syndromes. In patients with chest pain that is compatible with myocardial ischemia, the characteristic STT–wave elevations that do not resolve with nitroglycerin (and are unlikely to be the result of an old infarction) become the basis for thrombolytic therapy or a primary percutaneous intervention. Rapid resolution of the ECG changes of myocardial infarction after reperfusion therapy has prognostic value and identifies patients with reperfused coronary arteries. Evidence of conduction abnormalities may help explain the mechanism of bradyarrhythmias and the likelihood of the need for a pacemaker. Conduction abnormalities may also aid in determining the cause of heart disease. For example, right bundle branch block and left anterior fascicular block are often seen in Chagas cardiomyopathy, and leftaxis deviation occurs in patients with a primum atrial septal defect. 2. Echocardiography Another frequently ordered cardiac diagnostic test, echocardiography is based on the use of ultrasound directed at the heart to create images of cardiac anatomy and display them in real time on a monitor screen. Twodimensional echocardiography is usually accomplished by placing an ultrasound transducer in various positions on the anterior chest and obtaining crosssectional images of the heart and great vessels in a variety of standard planes. In general, twodimensional echocardiography is excellent for detecting any anatomic abnormality of the heart and great vessels. With twodimensional echocardiographic imaging of dynamic left ventricular crosssectional anatomy ventricular wall motion can be interrogated in multiple planes and left ventricular wall thickening during systole (an important measure of myocardial viability) can be assessed. In addition to demonstrating segmental wall motion abnormalities, echocardiography can estimate left ventricular volumes and ejection fraction. Transesophageal echocardiography (TEE) involves the placement of smaller ultrasound probes on a gastroscopic device for placement in the esophagus behind the heart; it produces much higher resolution images of posterior cardiac structures. TEE has made it possible to detect left atrial thrombi, small mitral valve vegetations, and thoracic aortic dissection with a high degree of accuracy. Recent advances in image processing of multiplanar images have permitted realtime threedimensional echocardiography, which is especially useful for evaluating structural valve pathology and guiding repair or replacement decisions. In addition, threedimensional images are more accurate at determining chamber volumes. The older analog echocardiographic display, referred to as Mmode, motionmode, or timemotion mode, is currently used for its high axial and temporal resolution. It is superior to twodimensional echocardiography for measuring the dimensions of structures in its axial direction, and its very high sampling rate allows for the resolution of complex cardiac motion patterns. Its many disadvantages, including poor lateral resolution and the inability to distinguish whole heart motion from the motion of individual cardiac structures, have relegated it to a supporting role. Doppler ultrasound can be combined with twodimensional imaging to investigate blood flow in the heart and great vessels. It is based on determining the change in frequency (caused by the movement of blood in the given structure) of the reflected ultrasound compared with the transmitted ultrasound and converting this difference into flow velocity. In the colorflow Doppler echocardiography technique, frequency shifts in each pixel of a selected area of the twodimensional image are measured and converted into a color, depending on the direction of flow velocity, and the presence or absence of turbulence. When these color images are superimposed on the twodimensional echocardiographic image, a moving color image of blood flow in the heart is created in real time. This is extremely useful for detecting regurgitant blood flow across cardiac valves and any abnormal communications in the heart. Tissue Doppler imaging is similar to colorflow Doppler except that myocardial tissue movement velocity is interrogated. This allows for the quantitation of the rate of tissue contraction and relaxation, which is a measure of myocardial performance that can be applied to systole and diastole. Tissue Doppler images can be used to evaluate myocardial strain regionally or globally. Reduced left ventricular systolic strain is an early sign of myocardial weakness that can occur before other measures, such as left ventricular ejection fraction, are reduced. Global left ventricular strain is currently being used to detect early drug toxicity to the heart. Because colorflow imaging cannot resolve very high velocities, another Doppler mode must be used to quantitate the exact velocity and estimate the pressure gradient of the flow when high velocities are suspected. Continuous wave Doppler, which almost continuously sends and receives ultrasound along a beam that can be aligned through the heart, is extremely accurate at resolving very high velocities such as those encountered with valvular aortic stenosis. The disadvantage of this technique is that the source of the high velocity within the beam cannot always be determined but must be assumed, based on the anatomy through which the beam passes. When there is ambiguity about the source of the high velocity, pulsed wave Doppler is more useful. This technique is rangegated such that specific areas along the beam (sample volumes) can be investigated. One or more sample volumes can be examined, and determinations made concerning the exact location of areas of highvelocity flow. Downloaded 202517 8:40 A Your IP is Chapter 5: Approach to Cardiac Disease Diagnosis, Michael H. Crawford Page 9 / 16 Doppler echocardiography ©2025 McGraw has now Hill. All Rights largely replaced Reserved. Terms ofcardiac catheterization Use Privacy Policy for deriving Notice hemodynamics to estimate the severity of valve stenosis. Accessibility Recorded Doppler velocities across a valve can be converted to pressure gradients by the use of the simplified Bernoulli equation (pressure gradient = 4 × velocity2). Cardiac output can be measured by Doppler from the velocity recorded at cardiac anatomic sites of known size visualized on the two pressure gradient of the flow when high velocities are suspected. Continuous wave Doppler, which almost continuously sends and receives ultrasound Universidad along a beam that can be aligned through the heart, is extremely accurate at resolving very high velocities such as those encountered withde Monterrey valvular aortic stenosis. The disadvantage of this technique is that the source of the high velocity within the beam cannot always be determined but Access Provided by: must be assumed, based on the anatomy through which the beam passes. When there is ambiguity about the source of the high velocity, pulsed wave Doppler is more useful. This technique is rangegated such that specific areas along the beam (sample volumes) can be investigated. One or more sample volumes can be examined, and determinations made concerning the exact location of areas of highvelocity flow. Doppler echocardiography has now largely replaced cardiac catheterization for deriving hemodynamics to estimate the severity of valve stenosis. Recorded Doppler velocities across a valve can be converted to pressure gradients by the use of the simplified Bernoulli equation (pressure gradient = 4 × velocity2). Cardiac output can be measured by Doppler from the velocity recorded at cardiac anatomic sites of known size visualized on the two dimensional echocardiographic image. Cardiac output and pressure gradient data can be used to calculate the stenotic valve area with remarkable accuracy. A complete echocardiographic examination including twodimensional and Mmode anatomic and functional visualization and color, pulsed, and continuous wave Doppler examination of blood flow provides a considerable amount of information about cardiac structure and function. A full discussion of the usefulness of this technique is beyond the scope of this chapter, but individual uses of echocardiography will be discussed in later chapters. Unfortunately, echocardiography is not without its technical difficulties and pitfalls. Like any noninvasive technique, it is not 100% accurate. Furthermore, it is impossible to obtain highquality images or Doppler signals in as many as 5% of patients, especially those with emphysema, chest wall deformities, and obesity. Although TEE has made the examination of such patients easier, it does not solve all the problems of echocardiography. Despite these limitations, the technique is so powerful that it has moved out of the noninvasive laboratory and is now frequently being used in the operating room, the clinic, the emergency department, and even the cardiac catheterization laboratory, to help guide procedures without the use of fluoroscopy. New handheld echocardiographic machines may soon rival the cardiac physical examination at the bedside. Some of these small new devices use the physician’s smart phone to display the echocardiographic images. 3. Nuclear cardiac imaging Nuclear cardiac imaging involves the injection of tracer amounts of radioactive elements attached to larger molecules or to the patient’s own blood cells. The tracerlabeled blood is concentrated in certain areas of the heart, and a gamma ray detection camera is used to collect the radioactive emissions and form an image of the distribution of the tracer in the particular area. The singlecrystal gamma camera produces planar images of the heart, depending on the relationship of the camera to the body. Multiplehead gamma cameras, which rotate around the patient, can produce single photon emission computed tomography (SPECT) images, displaying the cardiac anatomy in slices, each about 1cm thick. Positron emission tomography scanning requires special isotopes and imaging equipment, but positrons are less susceptible to attenuation by the chest wall and can detect cellular metabolism as well as perfusion. The presence of metabolism in a malfunctioning or poorly perfused wall suggests myocardial viability. A. MYOCARDIAL PERFUSION IMAGING The most common tracers used for imaging regional myocardial blood flow distribution are thallium201 and the technetium99m–based agents, such as sestamibi. Thallium201, a potassium analog that is efficiently extracted from the bloodstream by viable myocardial cells, is concentrated in the myocardium in areas of adequate blood flow and living myocardial cells. Thallium perfusion images show defects (a lower tracer concentration) in areas where blood flow is relatively reduced and in areas of damaged myocardial cells. If the damage is from frank necrosis or scar tissue formation, very little thallium will be taken up; ischemic cells may take up thallium more slowly or incompletely, producing relative defects in the image. Myocardial perfusion problems are separated from nonviable myocardium by the fact that thallium eventually washes out of the myocardial cells and back into the circulation. If a defect detected on initial thallium imaging disappears over a period of 3–24 hours, the area is presumably viable. A persistent defect suggests a myocardial scar. In addition to detecting viable myocardium and assessing the extent of new and old myocardial infarctions, thallium201 imaging can also be used to detect myocardial ischemia during stress testing (see later section on stress testing) as well as marked enlargement of the heart or dysfunction. The major problem with thallium imaging is photon attenuation because of chest wall structures, which can give an artifactual appearance of defects in the myocardium. The technetium99m–based agents take advantage of the shorter halflife of technetium (6 hours; the halflife of thallium201 is 73 hours); this allows for use of a larger dose, which results in higher energy emissions and higher quality images. Technetium99m’s higher energy emissions scatter less and are attenuated less by chest wall structures, reducing the number of artifacts. Because sestamibi undergoes considerably less washout after the initial myocardial uptake than thallium does, the evaluation of perfusion versus tissue damage requires two separate injections. In addition to detecting perfusion deficits, myocardial imaging with the SPECT system allows for a threedimensional reconstruction of the heart, which can be displayed in any projection on a monitor screen. Such images can be formed at intervals during the cardiac cycle to create an image of the beating heart, which can be used to detect wall motion abnormalities and derive left ventricular volumes and ejection fraction. Matching wall motion abnormalities202517 Downloaded with perfusion 8:40 Adefects provides Your IP is additional confirmation that the perfusion defects visualized are true and not artifacts of photon Chapter attenuation. Also, extensive perfusion defects and wall Michael 5: Approach to Cardiac Disease Diagnosis, H. Crawford should be accompanied by decreases in ejection fraction. Page 10 / 16 motion abnormalities ©2025 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility B. POSITRON EMISSION TOMOGRAPHY and are attenuated less by chest wall structures, reducing the number of artifacts. Because sestamibi undergoes considerably less washout after the Universidad de Monterrey initial myocardial uptake than thallium does, the evaluation of perfusion versus tissue damage requires two separate injections. Access Provided by: In addition to detecting perfusion deficits, myocardial imaging with the SPECT system allows for a threedimensional reconstruction of the heart, which can be displayed in any projection on a monitor screen. Such images can be formed at intervals during the cardiac cycle to create an image of the beating heart, which can be used to detect wall motion abnormalities and derive left ventricular volumes and ejection fraction. Matching wall motion abnormalities with perfusion defects provides additional confirmation that the perfusion defects visualized are true and not artifacts of photon attenuation. Also, extensive perfusion defects and wall motion abnormalities should be accompanied by decreases in ejection fraction. B. POSITRON EMISSION TOMOGRAPHY Positron emission tomography (PET) is a technique using tracers that simultaneously emit two highenergy photons. A circular array of detectors around the patient can detect these simultaneous events and accurately identify their origin in the heart. This results in improved spatial resolution compared with SPECT. It also allows for correction of tissue photon attenuation, resulting in the ability to accurately quantify radioactivity in the heart. PET can be used to assess myocardial perfusion and myocardial metabolic activity separately by using different tracers coupled to different molecules. Most of the tracers developed for clinical use require a cyclotron for their generation; the cyclotron must be near the PET imager because of the short halflife of the agents. Agents in clinical use include oxygen15 (halflife 2 minutes), nitrogen13 (halflife 10 minutes), carbon11 (halflife 20 minutes), and fluorene18 (halflife 110 minutes). These tracers can be coupled to many physiologically active molecules for assessing various functions of the myocardium. Because rubidium82, with a halflife of 75 seconds, does not require a cyclotron and can be generated on site, it is frequently used with PET scanning, especially for perfusion images. Ammonia containing nitrogen13 and water containing oxygen15 are also used as perfusion agents. Carbon11–labeled fatty acids and 18Ffluorodeoxyglucose are common metabolic tracers used to assess myocardial viability, and acetate containing carbon11 is often used to assess oxidative metabolism. The main clinical uses of PET scanning involve the evaluation of coronary artery disease. It is used in perfusion studies at rest and during pharmacologic stress (exercise studies are less feasible). In addition to a qualitative assessment of perfusion defects, PET allows for a calculation of absolute regional myocardial blood flow or bloodflow reserve. PET also assesses myocardial viability, using the metabolic tracers to detect metabolically active myocardium in areas of reduced perfusion. The presence of viability implies that returning perfusion to these areas would result in improved function of the ischemic myocardium. Although many authorities consider PET scanning the gold standard for determining myocardial viability, it has not been found to be 100% accurate. Thallium reuptake techniques and echocardiographic and magnetic resonance imaging (MRI) of delayed myocardial enhancement have proved equally valuable for detecting myocardial viability in clinical studies. C. RADIONUCLIDE ANGIOGRAPHY Radionuclide angiography is based on visualizing radioactive tracers in the cavities of the heart over time. Radionuclide angiography is usually done with a single gamma camera in a single plane, and only one view of the heart is obtained. The most common technique is to record the amount of radioactivity received by the gamma camera over time. Although volume estimates by radionuclide angiography are not as accurate as those obtained by other methods, the ejection fraction is quite accurate. Wall motion can be assessed in the one plane imaged, but the technique is not as sensitive as other imaging modalities for detecting wall motion abnormalities. Although still used by some to follow ejection fraction serially, it has largely been replaced by echocardiography. D. 99mTcPYP I M A G I N G 99mtechnetiumpyrophosphate imaging was originally used to detect myocardial infarction but has evolved as simple, diagnostic test for the rare cardiac disease amyloidosis which causes heart failure. TcPYP radioisotope is injected intravenously, and nongated cardiac SPECT and planar images are obtained 1 hour post injection. There is increased myocardial uptake of 99mTcPYP in cardiac amyloidosis. Planar and SPECT images are used for visual interpretation, semiquantitative and quantitative assessment of myocardial uptake in comparison to rib uptake and lung uptake. PYP imaging has ability to specifically identify and differentiate the types of amyloidosis noninvasively. 4. Other cardiac imaging A. CHEST RADIOGRAPHY Chest radiography is used infrequently now for evaluating cardiac structural abnormalities because of the superiority of echocardiography in this regard. The chest radiograph, however, is a rapid, inexpensive way to assess pulmonary anatomy and is very useful for evaluating pulmonary venous congestion and hypoperfusion or hyperperfusion. In addition, abnormalities of the thoracic skeleton are found in certain cardiac disorders, and radiographic corroboration may help with the diagnosis. Detection of intracardiac calcium deposits by the radiograph or fluoroscopy is of some value in finding coronary artery, valvular, or pericardial disease. Chest Xray (CXR) also helps in identification and location of cardiac devices, implants, and Downloaded 202517 monitors. It can provide8:40 A information useful Your IP is about cardiac devices like pacemakers and ICDs, assessing position, number of cardiac leads, Chapter 5: Approach to Cardiac Disease Diagnosis, dislodgement of leads, and also immediate Michael postprocedure H. Crawford complications. Page 11 / 16 CXR also helps in identification of prosthetic heart valves, valve rings, clips ©2025 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility and in some cases, vascular stents. B. COMPUTED TOMOGRAPHIC SCANNING Universidad deinMonterrey Chest radiography is used infrequently now for evaluating cardiac structural abnormalities because of the superiority of echocardiography this regard. The chest radiograph, however, is a rapid, inexpensive way to assess pulmonary anatomy and is very useful for evaluating pulmonary Access Provided by: venous congestion and hypoperfusion or hyperperfusion. In addition, abnormalities of the thoracic skeleton are found in certain cardiac disorders, and radiographic corroboration may help with the diagnosis. Detection of intracardiac calcium deposits by the radiograph or fluoroscopy is of some value in finding coronary artery, valvular, or pericardial disease. Chest Xray (CXR) also helps in identification and location of cardiac devices, implants, and monitors. It can provide useful information about cardiac devices like pacemakers and ICDs, assessing position, number of cardiac leads, dislodgement of leads, and also immediate postprocedure complications. CXR also helps in identification of prosthetic heart valves, valve rings, clips and in some cases, vascular stents. B. COMPUTED TOMOGRAPHIC SCANNING Cardiac computed tomographic (CT) scanning is a noninvasive cardiac imaging technique that uses Xray radiation to image the heart and associated blood vessels. Cardiac CT has been in use since late 1990s but the advances in CT technology and robust data from multiple randomized clinical trials has increased its use in clinical practice dramatically in the past two decades. With the latest CT technology, cardiac CT can provide images with high spatial and temporal resolution and can acquire an entire cardiac image in one heartbeat. This makes cardiac CT imaging useful for the assessment of coronary artery disease. Noncontrast cardiac CT is primarily used for the assessment of coronary artery calcium which is an indicator of atherosclerosis in the coronary arteries. A coronary calcium score helps in risk stratification of patients and identifies patients who benefit from cardiac preventive therapy. Coronary CT angiography (CTA) uses intravenous iodinated contrast to increase vessel visualization. CTA uses cardiac ECG gating to acquire coronary images when cardiac movement is at its least. Sublingual nitroglycerin is used to enhance visualization of the coronary arteries. Two types of ECG gating are used for coronary CTA. Prospective ECG gating ideally requires the heart rate to be less than 65 bpm to reduce motion artifacts and acquires images during mid to enddiastolic phase which corresponds to around 70% of the RR interval. βBlockers or calcium channel blockers are used to reduce heart rate if it is more than 70 bpm and if there are no contraindications to their use. Retrospective ECG gating is used when the heart rate is high or in irregular heart rhythms like atrial fibrillation. In retrospective ECGgated studies, images are acquired throughout the cardiac cycle and images from different phases of cardiac cycle are used to assess coronary anatomy. This technique can also be used to assess cardiac function with cine sequences. Compared to prospective CTA, retrospective CTA delivers a higher radiation dose. In addition, coronary CTA can provide an anatomical assessment of coronary artery disease such as plaque burden and plaque characteristics which may identify highrisk plaque. Coronary CTA can provide a noninvasive hemodynamic assessment of entire coronary tree from which fractional flow reserve can be calculated. This information helps in planning coronary interventions. With increases in spatial resolution, some CT scanners can assess coronary stent patency as well. Cardiac CTA has also shown great sensitivity in assessing coronary artery bypass graft patency and occlusion. Other uses of cardiac CT include the assessment of pericardial disease such as calcification and cysts, although complex effusions and masses are better assessed by MRI. CT scanning is also very useful for detecting other potential causes of chest pain, including dissection of the aorta or a coronary artery and pulmonary embolism. With recent advances in structural heart interventions, cardiac CT has played a complimentary role along with other cardiac imaging modalities. With retrospective gating, cardiac function and valve excursion can be assessed. Cardiac CT with 3D imaging of the heart and surrounding structures provides valuable information for preprocedural planning, patient selection, and peripheral vascular access. Cardiac CT can also provide anatomic information regarding heart valves when poor acoustic windows or heavy calcification limit visualization of valve anatomy with echocardiography. Myocardial CT perfusion, Hybrid PET, or nuclear scanners plus CT scanners are now available and can provide anatomic, perfusion, and myocardial viability information. C. MAGNETIC RESONANCE IMAGING MRI has improved dramatically over the past two decades and is now increasingly used for cardiac imaging. Cardiac MRI (CMR) provides good spatial resolution, adequate temporal resolution, and has a unique ability to assess tissue characteristics such as edema, inflammation, fibrosis, and scar. Unlike cardiac CT or nuclear perfusion imaging, CMR does not use ionizing radiation for image acquisition. MRI uses a powerful superconducting electromagnet which creates a strong magnetic field. Hydrogen ions that are abundant in the body are used to generate signal for the image formation. The hydrogen nucleus has a single positively charged proton which spins along its own axis, causing a small electromagnetic field. When placed in a large magnetic field, these protons also spin about the axis of the external magnetic field which is called precession. When patient is placed in MRI machine, most of the protons precess aligning to the external magnetic field but some protons align opposite to the external magnetic field. The net magnetization which is aligned with the external magnetic field is called longitudinal magnetization. A radiofrequency (RF) pulse is used to excite the protons which flips them in the transverse plane causing net transverse magnetization. After the RF pulse is removed, the excited protons release energy and relax back to their resting state of longitudinal magnetization. This released signal is used to create the images in MRI. T1 is the time it takes for longitudinal magnetization to recover to 63% of its maximum value. Its value depends on the surrounding molecules and is specific for different tissues. T2 is the time it takes for transverse magnetization to decay to 37% of its maximum value. It depends on local magnetic field and is specific for different tissues. Downloaded The differences 202517 in the 8:40 A Your IPT1 is and T2 values of tissues are used to create the contrast for the T1 and T2weighted imaging in MRI. Chapter 5: Approach to Cardiac Disease Diagnosis, Michael H. Crawford Page 12 / 16 Different CMR techniques ©2025 McGraw and sequences Hill. All Rights Reserved.areTerms used to ofassess anatomy, Use Privacy function, Policy flow quantification, Notice Accessibility edema assessment, and tissue characterization. CMR is considered the gold standard for quantification of left and right ventricular volumetrics. It is widely used for anatomical assessment, functional assessment, and flow quantification in patients with congenital heart disease, cardiac shunts, and valvular heart disease. CMR is helpful for evaluating magnetization which is aligned with the external magnetic field is called longitudinal magnetization. A radiofrequency (RF) pulse is used to excite the Universidad protons which flips them in the transverse plane causing net transverse magnetization. After the RF pulse is removed, the excited protonsde Monterrey release energy and relax back to their resting state of longitudinal magnetization. This released signal is used to create the images in Access MRI. T1Provided by: is the time it takes for longitudinal magnetization to recover to 63% of its maximum value. Its value depends on the surrounding molecules and is specific for different tissues. T2 is the time it takes for transverse magnetization to decay to 37% of its maximum value. It depends on local magnetic field and is specific for different tissues. The differences in the T1 and T2 values of tissues are used to create the contrast for the T1 and T2weighted imaging in MRI. Different CMR techniques and sequences are used to assess anatomy, function, flow quantification, edema assessment, and tissue characterization. CMR is considered the gold standard for quantification of left and right ventricular volumetrics. It is widely used for anatomical assessment, functional assessment, and flow quantification in patients with congenital heart disease, cardiac shunts, and valvular heart disease. CMR is helpful for evaluating patients with poorquality echocardiograms due to limited acoustic windows. Chamber volumes, wall function, blood flow quantification, and valve morphologies can be evaluated without the use of contrast agents. Gadolinium is a noniodinated, paramagnetic contrast agent that is used intravenously in CMR for performing perfusion imaging, scar assessment, and magnetic resonance angiography. Gadolinium stays in the extracellular space and does not cross intact cell membranes. Late gadolinium enhancement (LGE) images are obtained 5–10 minutes after giving intravenous gadolinium contrast. Gadolinium persists in tissues with cellular injury, inflammation, necrosis, and washes out slowly in diseases with increased extracellular space like edema, infiltrative cardiomyopathy, and scar tissue. An inversion recovery sequence is used for LGE assessment which appears as a bright signal on a black/nulled myocardium. The major limitation of gadoliniumbased contrast is the risk of nephrogenic systemic fibrosis (NSF) in chronic kidney disease patients with glomerular filtration rates less than 30 mL/kg/h. With the more recent use of macrocyclic gadolinium contrast, the incidence of NSF has been markedly reduced. LGE patterns help in differentiating ischemic from nonischemic cardiomyopathy and can diagnose certain cardiomyopathies such as cardiac amyloidosis, hypereosinophilic endocarditis, sarcoidosis, and myocarditis. LGE in ischemic cardiomyopathy helps in risk stratification, the assessment of viability, and for predicting functional recovery postrevascularization. For arrhythmia patients, CMR with LGE helps with scar mapping in ventricular tachycardia and left atrial mapping in atrial fibrillation to plan ablation therapy. LGE also can risk stratify patients with hypertrophic cardiomyopathy by scar quantification and diagnose rare cardiomyopathies associated with arrhythmias. Apart from LGE sequences, myocardial parametric mapping sequences like T1 mapping, T2 mapping, and T* mapping are used for tissue characterization and allows quantitative assessment of myocardial fibrosis, edema, and iron overload, respectively. Stress CMR is performed with gadoliniumbased contrast agents and vasodilators such as adenosine or regadenoson, or myocardial contractility stimulants such as dobutamine to evaluate perfusion reserve in coronary artery disease and assess for microvascular coronary disease. Magnetic resonance angiography with gadoliniumbased contrast allows visualization of arterial and venous connections and can be used to assess structures such as the ascending and/or descending aorta, peripheral vasculature, and pulmonary veins. Vascular imaging can be performed with noncontrast CMR angiography sequences as well. CMR also plays an important role in assessment of cardiac masses, pericardial disease, and myopericarditis. Patients should be screened for metallic implants and cardiac implantable devices. Only patients with MRI conditional and MRI safe devices can get CMR. Some devices may require reprogramming into an MRI safe mode. Some of the limitations of CMR at this time include the length of the studies, their cost, and the relative nonavailability of MRI systems in acute patient care areas compared to CT. CMR can last 45–60 minutes or more. This can be shortened by selecting focused imaging protocols that are specific for the indication of the study. CMR also needs patient cooperation for breath hold sequences to reduce respiratory and motion artifact. Unstable patients or patients with profound shortness of breath are not good candidates for the study. Patients with claustrophobia may need antianxiety medications or even sedation with anesthesia monitoring during image acquisition. Overall, CMR is a versatile tool for anatomic as well as functional assessment of the heart and has increasing indications in clinical practice. 5. Stress testing Stress testing in various forms is most frequently applied in cases of suspected or overt ischemic heart disease (Table 5–3). Because ischemia represents an imbalance between myocardial oxygen supply and demand, exercise or pharmacologic stress increases myocardial oxygen demand and reveals an inadequate oxygen supply (hypoperfusion) in diseased coronary arteries. Stress testing can thus induce detectable ischemia in patients with no evidence of ischemia at rest. It is also used to determine cardiac reserve in patients with valvular and myocardial disease. Deterioration of left ventricular performance during exercise or other stresses suggests a diminution in cardiac reserve that would have therapeutic and prognostic implications. In addition, exercise testing can be used to detect the development of pulmonary hypertension with exercise. Although most stress test studies use some technique (Table 5–4) for directly assessing the heart, it is important not to forget that the symptoms of angina pectoris, extreme dyspnea, lightheadedness, or syncope during stress testing can be equally important in evaluating patients. Physical findings such as the development of pulmonary crackles, ventricular gallops, murmurs, peripheral cyanosis, hypotension, excessive increases in heart rate, or inappropriate decreases in heart rate also have diagnostic and prognostic value. It is therefore important that a symptom assessment and physical examination always be done before, during, and after stress testing. Downloaded 202517 8:40 A Your IP is Chapter 5: Approach to Cardiac Disease Diagnosis, Michael H. Crawford Table 5–3. Page 13 / 16 ©2025 McGraw Hill. All Rights Reserved. Some Indications for Stress Testing Terms of Use Privacy Policy Notice Accessibility implications. In addition, exercise testing can be used to detect the development of pulmonary hypertension with exercise. Although most stress test Universidad studies use some technique (Table 5–4) for directly assessing the heart, it is important not to forget that the symptoms of angina pectoris,de Monterrey extreme dyspnea, lightheadedness, or syncope during stress testing can be equally important in evaluating patients. Physical findings such as the Access Provided by: development of pulmonary crackles, ventricular gallops, murmurs, peripheral cyanosis, hypotension, excessive increases in heart rate, or inappropriate decreases in heart rate also have diagnostic and prognostic value. It is therefore important that a symptom assessment and physical examination always be done before, during, and after stress testing. Table 5–3. Some Indications for Stress Testing Evaluation of exertional chest pain Assess significance of known coronary artery disease Risk stratification of ischemic heart disease Determine exercise capacity Evaluate other exercise symptoms Detect exercise pulmonary hypertension Evaluate the severity of valvular heart disease Determine maximum oxygen consumption Precipitate exerciseinduced arrhythmias Table 5–4. Methods of Detecting Myocardial Ischemia During Stress Testing Electrocardiography Echocardiography Myocardial perfusion imaging Positron emission tomography Magnetic resonance imaging Electrocardiographic monitoring is the most common cardiac evaluation technique used during stress testing; it should be part of every stress test to assess heart rate and detect any arrhythmias. In patients with normal resting ECGs, diagnostic ST depression of myocardial ischemia has a fairly high sensitivity and specificity for detecting coronary artery disease in symptomatic patients if adequate stress is achieved (peak heart rate at least 85% of the patient’s maximum predicted rate, based on age and sex). Exercise ECG testing is an excellent lowcost screening procedure for patients with chest pain consistent with coronary artery disease, normal resting ECGs, and the ability to exercise to maximal levels. A myocardial imaging technique is usually added to the exercise evaluation in patients whose ECGs are abnormal or, for other reasons thought to be less accurate, for example, left bundle branch block. It is also used for determining the location and extent of myocardial ischemia in patients with known coronary artery disease. Imaging techniques, in general, enhance the sensitivity and specificity of the tests but are still not perfect, with false positive and falsenegative results occurring 5–10% of the time. Echocardiographic imaging in particular can assess the severity of valvular regurgitation and exerciseinduced pulmonary hypertension, which can be helpful in evaluating patients with valvular heart disease. Finally, cardiopulmonary exercise testing is used to measure maximum oxygen uptake, which is of prognostic value in systolic heart failure patients. Which adjunctive myocardial imaging technology to choose depends on the quality of the tests, their availability and cost, and the services provided by the laboratory. If these are all equal, the decision should be based on patient characteristics. For example, echocardiography might be appropriate when ischemia is suspected of developing during exercise and is profound enough to depress segmental left ventricular performance. On the other hand, perfusion scanning might be the best test to determine which coronary artery is producing the symptoms in a patient with known threevessel coronary artery disease and recurrent angina after revascularization. Choosing the appropriate form of stress is also important (Table 5–5). Exercise, the preferred stress for increasing myocardial oxygen demand, also simulates the patient’s normal daily activities and is therefore highly relevant clinically. There are essentially only two reasons for not choosing exercise stress; however, the patient’s inability to exercise adequately because of physical or psychological limitations, or the known superiority of pharmacologic stress in certain situations such as the presence of left bundle branch block. Table 5–5. Downloaded 202517 8:40 A Your IP is Types of Stress Tests Chapter 5: Approach to Cardiac Disease Diagnosis, Michael H. Crawford Page 14 / 16 ©2025 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Exercise Choosing the appropriate form of stress is also important (Table 5–5). Exercise, the preferred stress for increasing myocardial oxygen demand, also Universidad de Monterrey simulates the patient’s normal daily activities and is therefore highly relevant clinically. There are essentially only two reasons for not choosing Access Provided by: exercise stress; however, the patient’s inability to exercise adequately because of physical or psychological limitations, or the known superiority of pharmacologic stress in certain situations such as the presence of left bundle branch block. Table 5–5. Types of Stress Tests Exercise Treadmill Bicycle Pharmacologic Adenosine Dipyridamole Dobutamine Isoproterenol Regadenoson Other Pacing 6. Cardiac catheterization Cardiac catheterization is now mainly used for the assessment of coronary artery anatomy by coronary angiography. In fact, the cardiac catheterization laboratory has become more of a therapeutic than a diagnostic arena. Once significant coronary artery disease is identified, a variety of catheterbased interventions can be used to alleviate the obstruction to blood flow in the coronary arteries. At one time, hemodynamic measurements (pressure, flow, oxygen consumption) were necessary to accurately diagnose and quantitate the severity of valvular heart disease and intracardiac shunts. Currently, Doppler echocardiography has taken over this role almost completely, except in the few instances when Doppler studies are inadequate or believed to be inaccurate. Catheterbased hemodynamic assessments are still useful for differentiating cardiac constriction from restriction, despite advances in Doppler echocardiography. Currently, the catheterization laboratory is also more often used as a treatment arena for valvular and congenital heart disease. Certain stenotic valvular and arterial lesions can be treated successfully with catheterdelivered valve leaflet clips, the deployment of stents, or stentmounted bioprosthetic valves. Congenital and acquired shunts can also be closed by catheterdelivered devices. Myocardial biopsy is necessary to treat patients with heart transplants and is occasionally used to diagnose selected cases of suspected acute myocarditis. For this purpose, a bioptome is usually placed in the right heart, and several small pieces of myocardium are removed. Although this technique is relatively safe, myocardial perforation can occur. 7. Electrophysiologic testing and implantable devices Electrophysiologic testing uses catheterdelivered electrodes in the heart to induce rhythm disorders, determine their mechanisms, and localize the abnormal circuits. Certain tachyarrhythmias and structural abnormalities that facilitate rhythm disturbances can be treated by heating (i.e., radiofrequency energy ablation) or freezing (i.e., cryoablation) the underlying tissue. Bradyarrhythmias (i.e., slow heart rates that cause symptoms) are treated by the placement of a pacemaker that monitors rhythm disturbances and treats them accordingly through pacing. On the other hand, patients who are at high risk of lifethreate

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