L18 Valvular Heart Disease Pathophysiology PDF Spring 2024

Cardiovascular Anatomy and Conduction Valvular Heart Disease Mean Heart Chamber (Max/Min Pressure in mmHg): ´ Left ventricle (120/15) ´ Right ventricle (25/5) ´ Right atria (mean 4 to 5) ´ Pulmonary arteries/left atria (25/10) ´ Aorta (120/80) PASG 61310 Pathophysiology I Spring 2024 L18 Ithaca College, Physician Assistant Program Dr. Elena Mueller, PhD 1 Congenital Heart Defects Review of L17 Congenital Also valvular Congenital defects that maintain or create direct communication between the pulmonary and systemic circulatory systems cause blood to shunt from one system to another, mixing oxygenated and unoxygenated blood and increasing blood volume and, occasionally, pressure on the receiving side of the shunt. The direction of shunting through an abnormal communication depends on differences in pressure and resistance between the two systems. Direction of shunt blood flow is always from an area of high pressure to an area of low pressure. Review of L17 Ejection Fraction Review of L17 End diastolic volume = 120 mL End systolic volume = 50 mL Review of Physio Ejection volume (stroke volume) = 70 mL Ejection fraction = 70 mL/120 mL = 58% (normally 60%) If heart rate (HR) is 70 beats/minute, what is cardiac output? Cardiac output = HR * stroke volume = 70/min * 70 mL = 4900 mL/min. Review of Physio Review of Physio Cardiovascular Anatomy and Conduction the end-diastolic pressure when the ventricle has become filled, is a surrogate for end-diastolic volume EDV diastolic ´ Heart Sounds the pressure in the aorta ´ S1 and S2 ´S1 is the closing of Atrioventricular valves (Mitral and Tricuspid) at the start of ventricular systole ´S2 is the closing of the semilunar valves (Aortic and Pulmonic) at the end of ventricular systole ´Separation easy to hear on inspiration therefore S2 referred to as A2 and P2 https://physicaldiagnosispdx.com/cardiology-multimedia-new/ Diastole: - Atrial pressure > ventricular pressure → Tricuspid and mitral valves open → Filling - Contraction: Atrial pressure < ventricular pressure → Tricuspid and mitral valves close → S1 Mitral valve snaps before the tricuspid valve because the LV contracts first (but normally heard as just one sound) S1 is loudest at the apex (fifth intercostal space, mid-clavicular line) Systole: - ↑Ventricular pressure in isovolumetric contraction until ventricular pressure > pulmonary artery/aortic pressure → Pulmonic and aortic valves open → Ejection - End of ejection: Ventricular pressure falls → Pulmonic and aortic valves close → S2 Aortic sound occurs before the pulmonic sound because the aortic pressure is higher S2 is loudest at the base (upper sternal border) “Split S2”: The close of the aortic valve (A2) and the close of the pulmonary valve (P2) are not synchronized and become wider during inspiration (i.e. widened A2P2) because ↓intrathoracic pressure → ↑Venous return → Longer RV emptying time → Pulmonic valve closes later → P2 comes later Systole: - ↑Ventricular pressure in isovolumetric contraction until ventricular pressure > pulmonary artery/aortic pressure → Pulmonic and aortic valves open → Ejection - End of ejection: Ventricular pressure falls → Pulmonic and aortic valves close → S2 Aortic sound occurs before the pulmonic sound because the aortic pressure is higher S2 is loudest at the base (upper sternal border) “Split S2”: The close of the aortic valve (A2) and the close of the pulmonary valve (P2) are not synchronized and become wider during inspiration (i.e. widened A2P2) because ↓intrathoracic pressure → ↑Venous return → Longer RV emptying time → Pulmonic valve closes later → P2 comes later https://physicaldiagnosispdx.com/cardiology-multimedia-new/ Review of Physio https://physicaldiagnosispdx.com/cardiology-multimedia-new/ Review of Physio Review of Anatomy This is a young woman who was admitted to the hospital with soft tissue infections related to intravenous drug abuse; she was found to have a physiologically split S2. This is an older man with severe pulmonary hypertension and a right bundle branch block. Note the persistently split S2 as well as a split S1. Review of Anatomy Review of Anatomy Heart valves are subjected to high levels of repetitive mechanical stress, particularly at the hinge points of the leaflets; this is a consequence of (1) millions of cardiac contractions per year, (2) substantial tissue deformations during each contraction, and (3) transvalvular pressure gradients in the closed phase of each contraction of approximately 120mm Hg for the mitral and 80mm Hg for the aortic valve. These delicate structures can suffer cumulative damage and calcification that lead to clinically important dysfunction. Review of Anatomy Ø TOP: a section through the upper left ventricle, demonstrating both the aortic and the mitral valve. The aortic valve consists of three semilunar cusps, which fill with blood during diastole and seal off the aorta from the left ventricle to prevent backflow into the ventricle. The upper edge of each cusp forms a lunula, converging at the nodule. Each cusp contains an aortic sinus, with the right and left coronary arteries originating from the right and left aortic sinuses. This allows for blood to enter the coronary arteries in a controlled manner during diastole. During systole, blood from the ventricle pushes the semilunar cusps flat against the wall of the aorta to allow blood to reach the systemic circulation. Ø MIDDLE and BOTTOM: The AV valves consist of cusps (three in tricuspid and two in mitral valve) that are tethered to papillary muscles in the ventricular wall by chordae tendineae. Papillary muscles contract to prevent eversion of the valve leaflets during ventricular contraction, so that blood does not flow back into the atria. Review of Physio Valvular Heart Disease Review of Physio Type of Valve Lesions and Heart Consequences Stenosis: scarred, stiff, narrow openings Regurgitation: destroyed or scarred that fail to fully close Usually, stenosis coexists with some degree of regurgitation, and vice versa Valvular Heart Disease Ø Dysfunctional cardiac valves can be classified as either ´ narrow (stenosis) ´ leaky (regurgitation) Ø Although the tricuspid and pulmonary valves can become dysfunctional in patients with endocarditis, congenital lesions, or carcinoid syndrome, primary right-sided valvular abnormalities are relatively rare Ø Heart murmurs can be either systolic or diastolic. Ø During systole, while the left ventricle is contracting, the aortic valve is open and the mitral valve is closed. Turbulent flow can occur either because of ´ incompetent mitral valve, leading to regurgitation of blood back into the atrium, ´ a narrowed aortic valve Ø In diastole, the situation is reversed, with filling of the left ventricle through an open mitral valve while the aortic valve is closed. Turbulent flow occurs when there is ´ mitral valve narrowing ´ aortic valve incompetence ´ Tricuspid regurgitation ´ Pulmonic regurgitation rare ´ Aortic regurgitation ´ Mitral regurgitation ´ Tricuspid stenosis rare ´ Pulmonic stenosis rare ´ Aortic stenosis ´ Mitral stenosis Ø Valve stenosis usually develops slowly over time; lesions that cause valvular regurgitation can be either chronic or acute Valvular Heart Disease VALVULAR HEART DISEASE Ø Stenosis is the failure of a valve to open completely, obstructing forward flow. Ø The most frequent causes of the major valvular lesions are: Ø Acquired valvular stenosis is almost always due to a primary leaflet abnormality and is virtually always a chronic process (e.g., calcification or valve scarring). Aortic stenosis: calcification and sclerosis of anatomically normal or congenitally bicuspid aortic valves Ø Insufficiency results from failure of a valve to close completely, thereby allowing regurgitation (backflow) of blood. Aortic insufficiency: dilation of the ascending aorta, often secondary to hypertension and/or aging Ø Valvular insufficiency can result from either intrinsic disease of the valve leaflets (e.g., endocarditis) or disruption of the supporting structures (e.g., the aorta, mitral annulus, tendinous cords, papillary muscles, or ventricular free wall) without primary leaflet injury. Ø Valvular insufficiency can appear abruptly, as with chordal rupture, or insidiously as a consequence of leaflet scarring and retraction. Mitral stenosis: rheumatic heart disease (RHD) Mitral insufficiency: myxomatous degeneration (MVP), or left ventricular dilation due to ischemic or nonischemic heart failure Ø Stenosis or insufficiency can occur alone or together in the same valve Myxoma is a non-cancerous tumor growth, it contains mucus or gelatin like substance. The term is most often used in the context of Mitral valve prolapse, which is known more technically as "Myxomatous degeneration of the mitral valve." The burden of moderate or severe mitral and aortic valve disease in the United States. Aortic stenosis Ø Calcific or degenerative aortic valve disease is a common valvular lesion encountered among older patients Ø The two most common causes of AS severe enough to require surgery are § calcification of congenital bicuspid aortic valves and § degenerative calcification of tricuspid aortic valves o Rheumatic fever and radiation contribute to causes Ø Risk factors for degenerative calcific AS are similar to those for atherosclerosis: o Age – Each 10-year increase in age was associated with a twofold increased risk o Male sex – Twofold excess risk o Current cigarette smoking – 35 percent increase in risk o A history of hypertension – 20 percent increase in risk o High serum concentrations of lipoprotein(A) and low density lipoprotein (LDL) cholesterol o diabetes mellitus Aortic stenosis Pathogenesis of calcific aortic stenosis Ø The process of aortic valve deterioration and calcification is similar to vascular atherosclerosis endothelial dysfunction lipid accumulation inflammatory cell activation lipid and inflammatory cell infiltration across damaged endothelium cytokine release upregulation of several signaling pathways È Ø collagen is deposited fibrosis Ø valvular myofibroblasts differentiate phenotypically into osteoblasts o these guys deposit calcium hydroxyapatite crystals Ø Becomes clinically important when the valve orifice has narrowed to ~1 cm2 Ø Flow from LV to aortic outflow tract impaired Impaired L ventricular ejection o once LV ejection fraction falls below normal, valve replacement is indicated Ø Decreased net stroke output decreased perfusion of body tissue Ø Increased ventricular pressures LV hypertrophy Ø May increase LA pressure/size and pressure in pulmonary vessels (backward effect) Ø Murmur: systolic, crescendo-decrescendo (diamond shape), high pitch, harsh, at upper sternal border, radiating to carotids, often associated with thrill (vibration on chest) Ø Forward effects: decreased perfusion to body tissues =exertional dyspnea), decreased perfusion to brain =syncope, decreased perfusion to coronary arteries =chest pain, angina pectoris) Ø Advanced disease heart failure Aortic stenosis Calcific valvular degeneration Features include left ventricular hypertrophy and systolic ejection murmur C: Pressure–volume loop in aortic stenosis. The left ventricle becomes thickened and less compliant, forcing the diastolic pressure–volume curve upward, which results in elevated left ventricular end-diastolic pressure (aʹ). Because the left ventricle must pump against a fixed gradient (increased afterload), b increases to bʹ. Finally, the hypertrophy of the ventricle results in increased inotropic force, which shifts the isovolumic pressure curve leftward. Ø The gross morphologic hallmark of nonrheumatic, calcific aortic stenosis (involving either tricuspid or bicuspid valves) is mounded calcified masses on the outflow surfaces of the cusps that ultimately prevent cuspal opening. Ø The free edges of the cusps are usually not involved. Ø Microscopically, the layered architecture of the valve is largely preserved. Ø The calcific process begins in the valvular fibrosa on the outflow surface of the valve, at the points of maximal cusp flexion (near the margins of attachment). Ø Inflammation is variable, and metaplastic bone can be seen. Ø In aortic stenosis, the functional valve area is decreased by large nodular calcific deposits that can eventually cause measurable outflow obstruction; this subjects the left ventricular myocardium to progressively increasing pressure overload. Ø In contrast with rheumatic (and congenital) aortic stenosis, commissural fusion is not usually seen Calcific valvular degeneration in AS (A) Calcific aortic stenosis of a previously normal valve (viewed from aortic aspect). Nodular masses of calcium are heaped up within the sinuses of Valsalva (arrow). Note that the commissures are not fused, as occurs with postrheumatic aortic valve stenosis Aortic Regurgitation (B) Calcific aortic stenosis of a congenitally bicuspid valve. One cusp has a partial fusion at its center, called a raphe (arrow). Bicuspid aortic valve (BAV) disease affects as many as 0.5– 1.4% of the general population Aortic Regurgitation Cardinal features include § large hypertrophied left ventricle, § large aorta, § increased stroke volume, § wide pulse pressure, and § diastolic murmur. C: Pressure–volume loop in chronic aortic insufficiency. A marked enlargement in left ventricular volume shifts the diastolic pressure–volume curve rightward. Hypertrophy of the ventricle shifts the isovolumic pressure– volume curve leftward (not shown), but ultimately the ventricle dilates, contractility decreases, and the isovolumic pressure–volume curve shifts to the right. Stroke volume is enormous, although effective stroke volume may be minimally changed because much of the increase in stroke volume leaks back into the ventricle. Because the ventricle is constantly being filled from the mitral valve or the incompetent aortic valve, no isovolumic periods exist. Aortic regurgitation Ø Ø Ø Ø Ø Ø Flow goes back from aorta to LV Decreased net stroke output Increased ventricular pressures LV hypertrophy LV dilatation May increase LA pressure/size and pressure in pulmonary vessels Ø Murmur: § Blowing diastolic, decrescendo, often high pitch § and a crescendo–decrescendo systolic murmur, thought to arise from the increased stroke volume flowing across the aortic valve, can be heard at the left sternal border. Ø Hyperdynamic pulses—In chronic aortic regurgitation, a widened pulse pressure is responsible for several characteristic peripheral signs. § palpation of the peripheral pulse reveals a sudden rise and then drop in pressure (water-hammer or Corrigan pulse) § head bobbing (DeMusset sign) § rhythmic pulsation of the uvula (Müller sign) § arterial pulsation seen in the nail bed (Quincke pulse) Mitral Stenosis Rheumatic Fever and Rheumatic Valve Disease ü Rheumatic fever (RF) is an acute, immunologically mediated, multisystem inflammatory disease classically occurring a few weeks after group A streptococcal pharyngitis; Acute rheumatic carditis is a common manifestation of active RF and may progress over time to chronic rheumatic heart disease (RHD). ü RHD is characterized principally by deforming fibrotic valvular disease, particularly involving the mitral valve ü Used to be the most common cause of valvular defects ü Autoimmune disease triggered by a group A streptococcal infection: Antibodies cross-react against valve tissue. Streptococci are completely absent from the lesions Mitral Stenosis § Enlarged left atrium and small left ventricle § Thickening and fusion of mitral valve cusps, elevated left atrial pressure, left atrial enlargement, opening snap, and diastolic murmur. § C. Pressure–volume loop in mitral stenosis. Filling of the left ventricle is restricted from a to aʹ, decreasing stroke volume to bʹcʹ. ü Scarred tissue develops leading to stenosis or insufficiency (regurgitation). ü Mitral valve most often damaged ü Aortic valve second most often damaged Mitral Stenosis ü ü ü ü ü ü Calcific valvular degeneration in MS Flow LA to LV impaired Impaired ventricular filling Increased pulmonary pressures Increased risk for pulmonary edema Enlargement of LA and risk for atrial fibrillation May compromise right side of the heart (less frequent) ü Murmur: diastolic, crescendo, mid-late diastole, “late low-pitched diastolic rumble” Symptoms 1.Shortness of breath, hemoptysis (coughing up blood), and orthopnea (shortness of breath when lying down)— because of elevated left atrial, pulmonary venous, and pulmonary capillary pressures 2.Palpitations— Increased left atrial size predisposes patients with mitral stenosis to atrial arrhythmias. 3.Neurologic symptoms—Reduced outflow leads to dilation of the left atrium and stasis of blood flow. A thrombus in the left atrium is observed on echocardiography in approximately 20% of patients with mitral stenosis, and the prevalence increases with age, the presence of atrial fibrillation, the severity of stenosis, and any reduction in cardiac output. Embolic events that lead to neurologic symptoms occur in 8% of patients in sinus rhythm and in 32% of patients with chronic or paroxysmal atrial fibrillation. In addition, left atrial enlargement can sometimes impinge on the recurrent laryngeal nerve and lead to hoarseness (Ortner syndrome). (C and D) Mitral annular calcification, with calcific nodules at the base (attachment margin) of the anterior mitral leaflet (arrows). (C) Left atrial view. (D) Cut section of myocardium showing the lateral wall with dense calcification that extends into the underlying myocardium (arrow). Pulmonic valve Stenosis (PS) § Pulmonic stenosis (PS) is a narrowing or stricture of the pulmonary valve that causes resistance to blood flow from the RV into the PA § Is usually congenital (as in Noonan syndrome) § Commonly associated with other congenital cardiac defects § Narrowed valve orifice increases the RV afterload and the RV myocardium hypertrophies. If the obstruction is severe, pressure may back up into the RA, causing atrial dilation. § If there is a PFO or ASD, a right-to-left shunt may develop (cyanotic heart defect). § Pulmonary atresia is an extreme form of PS, with total fusion of the valve leaflets (blood cannot flow to the lungs). § Infants with severe PS or pulmonary atresia require continuous intravenous infusion of prostaglandin E1 to keep the DA open and to maintain pulmonary blood flow and oxygenation. § The treatment of choice for infants with moderate to severe PS is balloon angioplasty Tricuspid Valve Atresia ´ In tricuspid atresia, there will be no flow to the RV and no blood will be going to the pulmonary arteries resulting in pulmonary atresia. ´ In tricuspid atresia, the presence of VSD will determine the survival and degree of stenosis. § If there is no VSD, the baby will die if the PDA is not maintained. § If VSD is there, the baby will survive with cyanosis. ´ In small VSD there will be small RV and higher degree of stenosis because of severe pulmonary stenosis, while in large VSD the RV will be large with lesser degree of stenosis. Mitral Regurgitation (MR) ü Acute MR can occur in the setting of acute myocardial infarction (MI) with papillary muscle rupture, following blunt chest wall trauma, or during the course of infective endocarditis (IE) ü Flow goes back from LV to LA ü Increased pulmonary pressures. ü Increased risk for pulmonary edema ü LV hypertrophy and dilatation ü Patients with chronic mild-to-moderate MR are asymptomatic ü Patients with chronic severe MR present with fatigue, exertional dyspnea, and orthopnea ü Murmur: whole-systolic, like blowing air Major Causes of Mitral Regurgitation (MR) Etiologies Acute IE Papillary muscle rupture (post-MI) Chordal rupture/leaflet flail (MVP, IE) Blunt trauma Chronic Primary (affecting leaflets, chordae) Myxomatous (MVP, Barlow’s, forme fruste) Rheumatic fever IE (healed) Congenital (cleft, AV canal) Radiation Secondary (leaflets, chordae are “innocent bystanders”) Ischemic cardiomyopathy Dilated cardiomyopathy HOCM (with SAM) AF with LA enlargement and annular dilation (atrial functional MR) Mitral annular calcificationa Cyanotic Heart Disease Mitral Valve Prolapse MVP (Myxomatous Degeneration of the Mitral Valve) § MVP is the most common abnormality leading to primary mitral regurgitation (MR) § In mitral valve prolapse (MVP), one or both mitral valve leaflets are “floppy” and protrude into the left atrium during systole. § MVP affects approximately 2% to 3% of adults in the United States and is more common in women; § Most often an incidental finding on physical examination, but may lead to serious complications in a small minority of affected individuals § Most individuals diagnosed with MVP are asymptomatic § The etiologic basis for the changes that weaken the valve leaflets and associated structures is unknown in most cases. § MVP is associated with heritable disorders of connective tissue including Marfan syndrome, caused by fibrillin-1 (FBN1) mutations that alter cell-matrix interactions and dysregulate TGF-β signaling A 35-year-old man with Marfan syndrome presents with exertional dyspnea and pounding headaches for several months. His temperature is 37.0°C (98.6°F), pulse is 90/min, and blood pressure is 135/85 mmHg. On physical examination, the lungs are clear to auscultation. Cardiac auscultation reveals the murmur demonstrated below over the right sternal border. Palpation of the radial arteries shows a rapidly rising and falling arterial pulse. Which of the following is the most likely diagnosis? o Aortic stenosis o Mitral stenosis o Patent ductus arteriosus o Aortic regurgitation o Coarctation of the aorta A 35-year-old man with Marfan syndrome presents with exertional dyspnea and pounding headaches for several months. His temperature is 37.0°C (98.6°F), pulse is 90/min, and blood pressure is 135/85 mmHg. On physical examination, the lungs are clear to auscultation. Cardiac auscultation reveals the murmur demonstrated below over the right sternal border. Palpation of the radial arteries shows a rapidly rising and falling arterial pulse. Which of the following is the most likely diagnosis? water-hammer or Corrigan pulse A 70-year-old man comes to the emergency department for evaluation of dyspnea, dizziness, and associated chest pain. He became more concerned when he was walking up stairs and suddenly “passed out.” His medical history includes type 2 diabetes mellitus, for which he takes metformin. He smoked one pack per day for forty years but does not use excessive alcohol or illicit drugs. His temperature is 37.0°C (98.6°F), pulse is 80/min, and blood pressure is 139/75 mmHg. On physical examination, a systolic murmur is appreciated over the right sternal border, which decreases with sustained hand grip. Which of the following is the most likely underlying cause of this patient's condition? o Myxomatous valve degeneration o Chronic obstructive pulmonary disease o Aortic stenosis o Age-related valve calcification o Mitral stenosis o Bicuspid aortic valve o Patent ductus arteriosus o Untreated group A streptococcus infection o Aortic regurgitation o Coarctation of the aorta A 70-year-old man comes to the emergency department for evaluation of dyspnea, dizziness, and associated chest pain. He became more concerned when he was walking up stairs and suddenly “passed out.” His medical history includes type 2 diabetes mellitus, for which he takes metformin. He smoked one pack per day for forty years but does not use excessive alcohol or illicit drugs. His temperature is 37.0°C (98.6°F), pulse is 80/min, and blood pressure is 139/75 mmHg. On physical examination, a systolic murmur is appreciated over the right sternal border, which decreases with sustained hand grip. Which of the following is the most likely underlying cause of this patient's condition? o Myxomatous valve degeneration o Chronic obstructive pulmonary disease o Age-related valve calcification o Bicuspid aortic valve o Untreated group A streptococcus infection Classic features of symptomatic aortic stenosis (AS): dyspnea, decreased exercise tolerance, dizziness, syncope and a systolic murmur over the right sternal border. The most common cause of aortic stenosis in adults over the age of 60 is age-related calcification. References REQUIRED TEXTBOOK § Hammer GD, McPhee SJ. Pathophysiology pf Disease: An Introduction to Clinical Medicine. McGraw-Hill Education Companies; 2019. ISBN-13: 978-1260026504. https://accessmedicine.mhmedical.com/book.aspx?bookid=2468 SUPPLEMENTAL MATERIALS § McCance, Kathryn L., and Sue E. Huether. Pathophysiology: The Biologic Basis for Disease in Adults and Children. 9th ed. Mosby Elsevier. 2024. ISBN-13: 978-0323789875 § Kumar, Vinay, et al. Robbins &Kumar Basic Pathology. 11th ed., Elsevier - Health Sciences Division. 2023. ISBN-13: 9780323790185 § Loscalzo J, Fauci A, Kasper D, Hauser S, Longo D, Jameson J. eds. Harrison's Principles of Internal Medicine, 21e. McGraw Hill; 2022. § Valvular heart disease on Osmosis

L18 Valvular Heart Disease Pathophysiology PDF Spring 2024

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