Valvular heart disease Study Guide

📖 Core Concepts Valvular heart disease = any pathology affecting one or more of the four cardiac valves (aortic, mitral, pulmonic, tricuspid). Stenosis = narrowing → ↑ pressure gradient, pressure overload of the upstream chamber. Regurgitation (insufficiency) = incomplete leaflet coaptation → backflow, volume overload of the downstream chamber. Functional consequence: pressure overload → concentric hypertrophy; volume overload → eccentric dilation. Key anatomy: valves are anchored in the dense connective‑tissue cardiac skeleton; annular dilation or leaflet calcification are common mechanisms. --- 📌 Must Remember Severe aortic stenosis: valve area < 1.0 cm² and mean gradient > 40 mmHg. Severe mitral stenosis: mitral valve area < 1.5 cm². Regurgitant fraction (RF): RF > 50 % = severe; 30 % – 49 % = moderate. Aortic regurgitation signs: wide pulse pressure, water‑hammer (Corrigan) pulse, early diastolic decrescendo murmur. Aortic stenosis murmur: harsh crescendo‑decrescendo systolic murmur, right 2nd intercostal space, radiates to carotids; pulse = pulsus parvus et tardus. Mitral regurgitation murmur: holosystolic at apex radiating to axilla; often with an S3. Mitral stenosis murmur: opening snap + low‑pitched diastolic rumble with presystolic accentuation; louder with more severe stenosis. Pregnancy high‑risk lesions: symptomatic severe AS, NYHA III‑IV AR, NYHA II‑IV MS, severe pulmonary hypertension, LVEF < 0.40, mechanical prostheses. --- 🔄 Key Processes Echo evaluation of stenosis Measure valve area (planimetry or continuity equation). Obtain mean pressure gradient via Doppler. Quantifying regurgitation Calculate RF = (Regurgitant volume ÷ Total stroke volume) × 100 %. Use color Doppler jet area, vena contracta, and PISA when needed. Management decision flow (Aortic Stenosis) Asymptomatic & non‑severe → watchful waiting, echo every 1–2 yr. Symptomatic or severe → SAVR (surgical aortic valve replacement) or TAVI (trans‑catheter) if high surgical risk. Balloon mitral valvuloplasty (for rheumatic MS) Indicated in symptomatic severe MS with favorable valve morphology; assess Wilkins score. Pregnancy monitoring Baseline echo → serial echo each trimester + functional class assessment → adjust anticoagulation (LMWH preferred for mechanical valves). --- 🔍 Key Comparisons Stenosis vs Regurgitation Stenosis: ↑ pressure gradient, ↑ upstream pressure, concentric hypertrophy. Regurgitation: ↑ volume return, ↑ downstream volume, eccentric dilation. Aortic vs Mitral Stenosis Aortic: systolic murmur, radiates to carotids, delayed carotid upstroke. Mitral: diastolic rumble, opening snap, loud S1. TAVI vs Surgical AVR TAVI: less invasive, preferred in high‑risk/older patients, limited valve durability data. SAVR: gold standard for younger/low‑risk, allows concomitant coronary surgery. Mechanical vs Bioprosthetic valve in pregnancy Mechanical: lifelong anticoagulation (warfarin ↔ teratogenic, LMWH often used). Bioprosthetic: no chronic anticoagulation, but may need earlier re‑operation. --- ⚠️ Common Misunderstandings Nitroglycerin in severe AS → Avoid: can cause profound hypotension (↓ preload) because the fixed obstruction cannot compensate. “Loud” murmurs always mean severe disease → Incorrect: murmur intensity depends on flow; early severe AS may have a softer murmur. All regurgitant lesions need surgery → False: asymptomatic mild/moderate regurg may be managed medically with afterload reduction and monitoring. Bicuspid aortic valve only causes stenosis → Wrong: can also cause regurgitation and associated aortopathy (root dilation). --- 🧠 Mental Models / Intuition Pressure‑overload → concentric wall thickening (think “pressing a rubber band tighter”). Volume‑overload → chamber dilation (think “balloon inflating”). Murmur timing = valve phase: systolic = stenosis of semilunar valves; diastolic = regurgitation of semilunar or stenosis of atrioventricular valves. Radiation pattern: aortic → carotids (upward flow); mitral → axilla (downward flow toward left arm). --- 🚩 Exceptions & Edge Cases Bicuspid aortic valve → earlier calcific AS (often before age 70). Rheumatic disease → can produce combined MS + AR; the opening snap may be delayed if severe. Carcinoid syndrome → right‑sided valve plaques → isolated tricuspid/pulmonic regurgitation, not left‑sided. Pregnancy → systemic vascular resistance falls → murmur intensity may decrease despite unchanged valve lesion. --- 📍 When to Use Which Echo vs Chest X‑ray: echo = definitive valve anatomy, severity, and ventricular function; chest X‑ray = assess chamber size, pulmonary congestion, aortic root dilation. Surgical AVR vs TAVI: choose TAVI for age > 75 yr or STS risk > 8 %; choose surgical AVR for younger, low‑risk, or when concomitant cardiac surgery required. Balloon valvuloplasty: indicated for isolated rheumatic mitral stenosis with favorable anatomy; avoid if heavy calcification or subvalvular disease. Medical therapy: use ACE‑I/ARB or CCB for AR to reduce afterload; diuretics for symptomatic volume overload in any regurgitant lesion. --- 👀 Patterns to Recognize Crescendo‑decrescendo systolic murmur + delayed carotid upstroke → classic aortic stenosis. Early diastolic decrescendo murmur at left sternal border + bounding pulses → aortic regurgitation. Holosystolic apex murmur radiating to axilla → mitral regurgitation. Low‑pitched diastolic rumble with opening snap after S2 → mitral stenosis. Inspiratory holosystolic murmur left lower sternal border that intensifies with inspiration → tricuspid regurgitation (Carvallo’s sign). --- 🗂️ Exam Traps Confusing “pulsus paradoxus” with “pulsus parvus et tardus.” The former is ↓ > 10 mmHg systolic pressure on inspiration (tamponade); the latter is weak, delayed carotid pulse in AS. Selecting nitroglycerin for angina in AS patients – a classic “wrong‑answer” choice; nitrates can precipitate hypotension. Assuming any diastolic murmur equals AR – diastolic murmurs can also be MS, pulmonary regurg, or Austin Flint murmur (AR‑induced). Using valve area ≤ 1.0 cm² alone to declare severe AS – must also consider mean gradient > 40 mmHg or flow‑status; low‑flow, low‑gradient AS can be severe despite borderline numbers. Treating mild regurgitation surgically – most mild/moderate lesions are managed medically; surgery is reserved for symptomatic severe disease or ventricular dysfunction.