L7. Disorders of the Cardiovascular System PDF

Disorders of the Cardiovascular System PATH 310 & 200 PATHOPHYSIOLOGY Outline: Objectives:  Cardiovascular System Heart has four chambers: 1. Right Atrium -Receives venous blood from whole of the body via the superior vena cava (SVC) at its upper end and...

Disorders of the Cardiovascular System PATH 310 & 200 PATHOPHYSIOLOGY Outline: Objectives:  Cardiovascular System Heart has four chambers: 1. Right Atrium -Receives venous blood from whole of the body via the superior vena cava (SVC) at its upper end and inferior vena cava (IVC) at its lower end. It pumps into Right ventricle (RV) through the tricuspid valve during the ventricular diastole. 2. 2. Right Ventricle -Opens into pulmonary artery through pulmonary valve 3. Left atrium - Receives oxygenated blood from pulmonary veins 4. Left ventricle -Blunt tip forms the apex of the heart Which of the following champers of the heart receives venous blood from whole of the body via the superior vena cava (SVC) at its upper end and inferior vena cava (IVC) at its lower end? 1. Left atrium 2. Right Atrium 3. Right Ventricle 4. Left ventricle  Cardiovascular System Heart has four valves: 1. Mitral valve 2. Aortic valve 3. Tricuspid valve 4. Pulmonic valve  Cardiovascular System The cardiovascular system begins its activity when the fetus is barely 1 month old, and it’s the last system to cease activity at the end of life. Functions of the Circulatory System Main function is transport. ⮚ Delivers oxygen and nutrients to the tissues ⮚ Carries waste products from cellular metabolism to the kidneys and other excretory organs ⮚ Circulates electrolytes and hormones ⮚ Transports various immune substances that contribute to the body’s defense mechanisms Helps to regulate temperature  Cardiovascular System Cardiac Cycle Used to describe the rhythmic pumping action of the heart Divided into two parts Systole: the period during which the ventricles are contracting Diastole: the period during which the ventricles are relaxed and filling with blood  Cardiovascular System Three layers: ⮚ Outer Epicardium ⮚ Middle Myocardium ⮚ Inner Endocardium and a covering Pericardium -The pericardial sac has two layers, a serous layer and a fibrous layer. It encloses the pericardial cavity which contains pericardial fluid. The pericardium fixes the heart to the mediastinum, gives protection against infection, and provides lubrication for the heart.  Cardiac output Amount of blood the heart pumps each minute Determined by ✓ CO = SV x HR Stroke volume: the amount of blood pumped with each beat Heart rate: the number of times the heart beats each minute For a resting adult CO = 70mL/beat x75beats/min = 5250 mL/min = 5.25 L/min ✓ Venous return and contractility Regulation of stroke volume is by three factors 1. Preload- Stretch of cardiac muscle prior to contraction. 2. Contractility - It is the strength of contraction at any given preload. 3. Afterload- The pressure that must be overcome before a semilunar valve can open is termed the afterload. https:/youtube.com/watch?v=vFRkSB46bl8&feature=share.txt Refers to the strength of contraction at any given preload? 1. Afterload 2. Preload 3. Contractility 4. stroke volume  Two Parts of the Circulatory System Pulmonary circulation ❖ Moves blood through the lungs and creates a link with the gas exchange function of the respiratory system. Include Right side of heart, Pulmonary artery, capillaries, and veins Systemic circulation ❖ Supplies all the other tissues of the body Eg: Left heart, Aorta and its branches, Capillaries supplying the brain and peripheral tissues, Systemic venous system and the vena cava  Two Parts of the Circulatory System Types of Circulation: ✔ Central circulation ✓ Blood that is in the heart and pulmonary circulation ✔ Peripheral circulation ✓ Blood that is outside the central circulation  Composition of the Arterial System 1. Arteries a. Thick-walled vessels with large amounts of elastic fibers b. Stretch during cardiac systole and recoil during diastole 2. Arterioles a. Serve as resistance vessels for the circulatory system b. Act as control valves through which blood is released as it moves into the capillaries  Effects of Peripheral Resistance and the Regulation of Blood Flow Blood pressure = cardiac output × peripheral vascular resistance regulated by: Autonomic nervous system (ANS) Kidneys (renin-angiotensin-aldosterone) Endocrine system (catecholamines, kinins, serotonin, histamine). Autonomic Control Centers for Cardiac Function and Blood Pressure ❖ Vasomotor center: sympathetic-mediated( Norepinephrine, Dopamine) acceleration of heart rate and blood vessel tone ❖ Cardioinhibitory center: parasympathetic-mediated( Acetylcholine) slowing of heart rate Effects of Peripheral Resistance and the Regulation of Blood Flow Factors affecting hemodynamic function Volume Pressure Resistance All of the following Factors affecting hemodynamic function EXCEPT a. Volume b. Pressure c. Resistance d. Contraction  Conduction system of the heart The heart rate is normally initiated by an electrical discharge from the S-A Node, the atria and ventricles then depolarize sequentially as electricity passes through the specialized conducting tissue. The sinus node (SA node) acts as a pacemaker that has its own intrinsic rate that is regulated by the autonomic nervous system : vagal activity slows the heart while sympathetic activity speeds it In the conduction system of the heart. Which of the following acts as a pacemaker that has its own intrinsic rate regulated by the autonomic nervous system? a) AV node b) SA node c) Bundle of HIS d) Purkinje fibers  Coronary Atherosclerosis Atherosclerosis is the abnormal accumulation of lipid deposits and fibrous tissue within arterial walls and lumen. ✓ In coronary atherosclerosis, blockages and narrowing of the coronary vessels reduce blood flow to the myocardium. ✓ Cardiovascular disease is the leading cause of death in the United States for men and women of all racial and ethnic groups. ✓ CAD, coronary artery disease, is the most prevalent cardiovascular disease in adults. Refers to the abnormal accumulation of lipid deposits and fibrous tissue within arterial walls and lumen a. Hypertension b. Atherosclerosis c. angina pectors d. heart failure  Pathophysiology of Atherosclerosis A, B: Atherosclerosis begins as monocytes and lipids enter the intima of an injured vessel. Smooth muscle cells proliferate within the vessel wall. C:contributing to the development of fatty accumulations and atheroma D: as the plaque enlarges, the vessels narrows and blood flow decreases E. the plaque might rupture, and a thrombus might form, obstructing blood flow.  Risk Factors for Atherosclerosis Nonmodifiable Modifiable ✓ Cigarette smoking Age Greater than 65 y/o ✓ High blood cholesterol Heredity (including race ✓ Hypertension Higher in African Americans, Mexican ✓ Physical inactivity Americans, Native Americans, Native ✓ Obesity and overweight Hawaiians, and some Asian Americans ✓ Diabetes mellitus Gender ✓ Contributing risk factors Men; after menopause, the death rate rises Stress in women Excessive alcohol intake  Risk Factors for Atherosclerosis Major Complications of Atherosclerosis: ✔ Ischemic heart disease ✔ Stroke ✔ Peripheral vascular disease https://www.youtube.com/watch?v=IkxxiaXdMmU  Hypertension Arterial Blood Pressure (Definitions) Systolic Pressure: pressure at the height of the pressure pulse Diastolic pressure: the lowest pressure Pulse pressure: the difference between systolic and diastolic pressure Mean arterial pressure: represents the average pressure in the arterial system during ventricular contraction and relaxation  Hypertension Hypertension Systolic pressure of less than 120 mm Hg and a diastolic pressure of less than 80 mm Hg are normal. Systolic pressures between 120- and 139-mm Hg and diastolic pressures between 80- and 89-mm Hg are considered prehypertensive. A diagnosis of hypertension is made if the systolic blood pressure is 140 mm Hg or higher and the diastolic blood pressure is 90 mm Hg or higher. A patient came to the emergency room with the signs and symptoms of hypertension. Which of the following readings reflects hypertension?  Categories of Hypertension 1. Primary hypertension (essential hypertension) The chronic elevation in blood pressure that occurs without evidence of other disease 2. Secondary hypertension The elevation of blood pressure that results from some other disorder, such as kidney disease 3. Malignant hypertension An accelerated form of hypertension  Classifications of Essential Hypertension 1. Systolic/diastolic hypertension Both the systolic and diastolic pressures are elevated. 2. Diastolic hypertension The diastolic pressure is selectively elevated. 3. Systolic hypertension The systolic pressure is selectively elevated.  Risk Factors for Hypertension Family history Age-related changes in blood pressure-More common in the elderly Race -More common in blacks than whites Insulin resistance and metabolic abnormalities Circadian variations Lifestyle factors Lifestyle Factors Contributing to Hypertension High salt intake Obesity Excess alcohol consumption Dietary intake of potassium, calcium, and magnesium Oral contraceptive drugs Stress  Hypertension: Clinical Manifestation Usually, NO symptoms other than elevated blood pressure Symptoms seen related to organ damage are seen late and are serious Retinal and other eye changes Renal damage Myocardial infarction Cardiac hypertrophy Stroke  Orthostatic Hypotension Definition An abnormal decrease in blood pressure on assumption of the upright position Causes ⮚ Decrease in venous return to the heart due to pooling of blood in lower part of body ⮚ Inadequate circulatory response to decreased cardiac output and a decrease in blood pressure ⮚ Condition that decreases vascular volume Eg: Dehydration, Excessive use of diuretics ⮚ Conditions that impair muscle pump function Eg: Bed rest, Spinal cord injury ⮚ Conditions that interfere with cardiovascular reflexes Eg: Medications, Disorders of autonomic nervous system An abnormal decrease in blood pressure on assumption of the upright position is termed as: a. Systolic hypertension b. Malignant hypertension c. Secondary hypertension d. Orthostatic hypotension  Acute coronary syndromes ▪ Acute myocardial infarction (MI), ST-segment elevation MI (STEMI), non-ST- segment elevation MI (NSTEMI), and unstable angina are recognized as a part of a group of clinical disorders known as acute coronary syndromes (ACS). ▪ In cardiovascular disease, death usually results from cardiac damage or complications of MI  Acute coronary syndromes CAUSES: ✓ Aging ✓ Drug use, especially cocaine and amphetamines ✓ Elevated serum triglyceride, total cholesterol, and low-density lipoprotein levels ✓ Excessive intake of saturated fats ✓ Gender -Men ✓ Hypertension ✓ Obesity ✓ Positive family history ✓ Sedentary lifestyle ✓ Smoking ✓ Stress  Acute coronary syndromes: Pathophysiology ✓ Rupture or erosion of plaque—an unstable and lipid-rich substance—initiates all coronary syndromes. The rupture results in platelet adhesions, fibrin clot formation, and activation of thrombin. ✓ For patients with unstable angina, a thrombus partially occludes a coronary vessel. This thrombus is full of platelets. ✓ The partially occluded vessel may have distal microthrombi that cause necrosis in some myocytes. The smaller vessels infarct, and patients are at higher risk for MI. These patients may progress to an NSTEMI. ✓ If a thrombus fully occludes the vessel for a prolonged time, this is known as an STEMI. In this type of MI, there’s a greater concentration of thrombin and fibrin.  Angina Pectoris ▪ A syndrome characterized by episodes or paroxysmal pain or pressure in the anterior chest caused by insufficient coronary blood flow. ▪ Physical exertion or emotional stress increases myocardial oxygen demand, and the coronary vessels are unable to supply sufficient blood flow to meet the oxygen demand.  Angina Pectoris Types of angina ⮚ Stable angina: predictable and consistent pain that occurs on exertion and is relieved by rest ⮚ Unstable angina (also called preinfarction angina or crescendo angina): symptoms occur more frequently and last longer than stable angina. The threshold for pain is lower, and pain may occur at rest. ⮚ Intractable or refractory angina: severe incapacitating chest pain ⮚ Variant angina (also called Prinzmetal’s angina): pain at rest with reversible ST- segment elevation; thought to be caused by coronary artery vasospasm ⮚ Silent ischemia: objective evidence of ischemia (such as electrocardiographic changes with a stress test), but patient reports no symptoms  Myocardial Infarction 1. Ischemia occurs first. It indicates that blood flow and oxygen demand are out of balance. 2. Ischemia can be resolved by improving flow or reducing oxygen needs. Electrocardiogram (ECG) changes indicate ST-segment depression or T-wave changes 3. Injury is the next stage. This occurs when the ischemia is prolonged enough to damage the area of the heart. ECG changes usually reveal ST-segment elevation. 4. In infarct, the third stage, actual death of the myocardial cells has occurred. ECG changes reveal abnormal Q waves  Myocardial Infarction Clinical Findings ▪ Persistent, crushing substernal chest pain that may radiate to the left arm, jaw, neck, or shoulder blades caused by reduced oxygen supply to the myocardial cells ▪ Cool extremities, perspiration, anxiety, and restlessness due to the release of catecholamines ▪ Fatigue and weakness caused by reduced perfusion to skeletal muscles ▪ Nausea and vomiting as a result of reflex stimulation of vomiting centers  Myocardial Infarction TEST RESULTS: ✓ Serial 12-lead ECG ✓ Serial cardiac enzymes and proteins may show a characteristic rise and fall, specifically CK-MB, the proteins troponin T and I, and myoglobin, to confirm the diagnosis of MI. ✓ Laboratory testing may reveal elevated white blood cell count, C-reactive protein level, and erythrocyte sedimentation rate due to inflammation, and increased glucose levels following the release of catecholamines. ✓ Echocardiography, Chest X-rays, Cardiac catheterization  Cardiac tamponade Pericardial effusion can lead to a condition called cardiac tamponade, in which there is compression of the heart due to the accumulation of fluid, pus, or blood in the pericardial sac. In cardiac tamponade, blood or fluid fills the pericardial space, compressing the heart chambers, increasing intracardiac pressure, and obstructing venous return.  Cardiac tamponade CAUSES ✔ Acute myocardial infarction ✔ Chronic renal failure requiring dialysis ✔ Connective tissue disorders Eg: as rheumatoid arthritis ✔ Effusion (from cancer, bacterial infections,TB) ✔ Hemorrhage from nontraumatic causes Eg: anticoagulant therapy ✔ Hemorrhage from trauma  Heart failure A syndrome rather than a disease, heart failure occurs when the heart can’t pump enough blood to meet the body’s metabolic needs. Heart failure results in intravascular and interstitial volume overload and poor tissue perfusion. The term heart failure indicates myocardial disease, in which there is a problem with the contraction of the heart (systolic failure) or filling of the heart (diastolic failure).  Heart failure CAUSES: ▪ Abnormal heart muscle function Eg: MI ▪ Increased left ventricular volume Eg: Valve disease, Infusion of large volume of IV fluids ▪ Increased left ventricular pressure Eg: Hypertension, COPD Pathophysiology of Heart Failure  Heart failure -Clinical Manifestations Right-sided failure: 1. RV cannot eject sufficient amounts of blood and blood backs up in the venous system. This resuts in perpheral edema, hepatomegaly, ascites, anorexia, nausea, weakness, and weight gain. Left-sided failure: 1. LV cannot pump blood effectively to the systemic circulation. Pulmonary venous pressures increase and result in pulmonary congestion with dyspnea, cough, crackles, and impaired oxygen exchange. Chronic heart failure is frequently biventricular.  Aortic Aneurysms An aneurysm is a localized dilatation and weakening of an arterial wall. The most common location is either the abdominal or thoracic aorta. The aneurysm may take different shapes: 1. A saccular shape is a bulging wall on one side, whereas a fusiform shape is a circumferential dilatation along a section of artery. 2. Dissecting aneurysms develop when there is a tear in the intima, allowing blood to flow along the length of the vessel between the layers of the arterial wall.  Aortic Aneurysms Etiology ✓ Common causes are: ✓ Atherosclerosis, ✓ Trauma (particularly, car accidents) ✓ Syphilis and other infections ✓ Congenital defects. ✓ Hypertension is present in half the patients diagnosed with aortic aneurysms.  Aortic Aneurysms Signs and symptoms ✓ Aneurysms are frequently asymptomatic for a long period of time until they become very large or rupture. ✓ Signs include severe pain and indications of shock. ✓ A dissecting aneurysm causes obstruction of the aorta and its branches as the intima peels back and blood flow is diverted between the layers. ✓ The dissection tends to progress down the aorta and sometimes back toward the heart as well. ✓ Dissection causes severe pain, loss of pulses, and organ dysfunction, as normal blood flow is lost. Many dissecting aneurysms ultimately rupture.  References: ▪ NORRIS, T. (2019). Porth’s Pathophysiology Concepts of Altered Health States. 10th ed. Wolters Kluwer ▪ Ian Peate, (2021) Fundamentals of applied pathophysiology: an essential guide for nursing & healthcare students. 4th ed. ▪ Hoboken, NJ : Wiley-Blackwell Dignle, M., Mulvihill, M., Zelman, M. & Tompary, E. (2011). Introductory pathophysiology for nursing & healthcare professionals. |Pearson ▪ Nair, M., & Peate, I. (2015). Pathophysiology for nurses at a glance (nursing and healthcare). Publisher: West Sussex, England: John Wiley & Sons, Inc PATH200/MACHS 56