USMLE/COMLEX 2 - Valvular Disease

Here are key facts for USMLE Step 2 & COMLEX-USA Level 2 from the Valvular Disease tutorial, as well as points of interest at the end of this document that are not directly addressed in this tutorial but should help you prepare for the boards. See the tutorial notes for further details and relevant links.

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• Aortic Stenosis (AS) – Clinical Presentation and Management

• Triad of exertional chest pain, syncope, and dyspnea is classic.
• Murmur: Systolic crescendo-decrescendo at right 2nd intercostal space, radiates to carotids.
• Pulsus parvus et tardus: delayed, diminished carotid upstroke.
• Most commonly due to calcific degeneration in elderly or bicuspid aortic valve in younger patients.
• Diagnostic test: Transthoracic echocardiogram (TTE).
• Definitive treatment: Surgical aortic valve replacement in symptomatic or severe cases.

• Mitral Stenosis (MS) – Rheumatic Origin and Management

• Most common cause: rheumatic heart disease.
• Murmur: Diastolic rumble with opening snap, best heard at the apex in the left lateral decubitus position.
• Symptoms: Dyspnea, orthopnea, palpitations due to atrial fibrillation from LA enlargement.
• CXR may show LA enlargement and pulmonary congestion.
• TTE confirms diagnosis; valve area <1.5 cm² indicates severe stenosis.
• Management: Diuretics for congestion, rate control + anticoagulation for Afib, balloon valvotomy or valve replacement if severe.

• Mitral Regurgitation (MR) – Acute vs. Chronic

• Acute MR causes: papillary muscle rupture post-MI, infective endocarditis.
• Chronic MR causes: myxomatous degeneration, mitral valve prolapse (MVP), or rheumatic fever.
• Murmur: Holosystolic at apex, radiates to axilla.
• TTE shows regurgitant jet; monitor left ventricular ejection fraction (EF) and end-systolic diameter (ESD).
• Indications for surgery: EF <60%, LVESD >40 mm, or symptoms.

• Aortic Regurgitation (AR) – Signs and Surgery Criteria

• Causes include aortic root dilation (e.g., Marfan syndrome, hypertension), endocarditis, and bicuspid valve.
• Murmur: Early diastolic decrescendo murmur at left sternal border.
• Physical signs: Wide pulse pressure, bounding pulse (Corrigan), head bobbing (de Musset).
• TTE confirms diagnosis.
• Surgery if symptomatic or if EF <55% or significant LV dilation.

• Valvular Replacement – Mechanical vs. Bioprosthetic

• Mechanical valves: durable, but require lifelong anticoagulation with warfarin.
• Bioprosthetic valves: shorter lifespan (10–15 years), but do not require long-term anticoagulation.
• Both types increase the risk of infective endocarditis.
• Require antibiotic prophylaxis for invasive dental procedures in high-risk patients.

• Mitral Valve Prolapse (MVP) – Most Common Valvulopathy

• Common in young women; may be asymptomatic or cause palpitations, chest pain.
• Murmur: Midsystolic click followed by late systolic murmur.
• Murmur occurs earlier with Valsalva or standing (↓ preload).
• Associated with myxomatous degeneration.
• Treatment: Beta blockers for symptomatic relief; monitor for progression to MR.

• Endocarditis Risk and Prophylaxis

• Valvular abnormalities increase risk, especially prosthetic valves, bicuspid valves, rheumatic valves, or MVP with regurgitation.
• Dental procedures with gingival manipulation warrant amoxicillin prophylaxis in high-risk patients.
• Most common organisms: Strep viridans (subacute), Staph aureus (acute, prosthetic).

• Echocardiography in Valve Disease

• TTE is first-line for diagnosis.
• TEE is more sensitive for posterior structures, prosthetic valves, and endocarditis evaluation.

• Indications for Surgical Valve Intervention

• Symptoms, even with preserved EF.
• Left ventricular dysfunction: EF <60% (MR), EF <55% (AR).
• Progressive chamber enlargement or pulmonary hypertension.

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• Heart Murmur Maneuvers

• Valsalva or standing: ↓ preload → ↑ murmur intensity in MVP and HOCM.
• Squatting or leg raise: ↑ preload → ↑ murmur intensity in AR and MR, ↓ MVP and HOCM.

• Functional Regurgitation

• Not due to primary valve disease but ventricular dilation, e.g., ischemic cardiomyopathy.
• May improve with heart failure therapy; surgical repair if severe.

• Mitral Annular Calcification

• Common in elderly or patients with chronic kidney disease.
• May lead to arrhythmias or contribute to MR.
• Often calcifies the fibrous annular ring rather than the leaflets.

• Post-MI Mitral Regurgitation

• Due to posteromedial papillary muscle rupture.
• Presents with sudden pulmonary edema, hypotension, and new murmur.
• Requires emergent surgical repair.

• Stroke Risk with Valvular Disease

• MS and MR with LA enlargement → increased risk of atrial fibrillation and thromboembolism.
• Use CHA₂DS₂-VASc to assess need for anticoagulation.

• Marfan Syndrome and Aortic Regurgitation

• Causes aortic root dilation, leading to AR.
• Mutation in fibrillin-1.
• Surgery indicated if root diameter >5.0–5.5 cm or significant AR develops.

• Prosthetic Valve Endocarditis

• Early (<60 days): usually Staph epidermidis.
• Late (>60 days): resembles native valve endocarditis.
• Diagnosis: TEE preferred.
• Requires IV antibiotics and possibly valve replacement.

• Hemoptysis in Mitral Stenosis

• Due to rupture of pulmonary bronchial veins from elevated left atrial pressure and pulmonary venous congestion.

• Diastolic vs. Systolic Murmurs

• Diastolic murmurs (MS, AR): always pathological.
• Systolic murmurs may be benign or pathological (AS, MR, MVP).

• Buttonhole (Fish Mouth) Valve Appearance

• Seen in rheumatic mitral stenosis.
• Results from leaflet thickening, commissural fusion, and fibrosis.

• Common Valve Lesion Causes

• Aortic stenosis: calcific degeneration, bicuspid valve.
• Aortic regurgitation: root dilation, endocarditis, Marfan.
• Mitral regurgitation: MVP, ischemia, myxomatous degeneration.
• Mitral stenosis: rheumatic fever.

• Prosthetic Valve Monitoring

• Regular echocardiography to monitor for dysfunction.
• Watch for hemolysis, pannus, paravalvular leak, and thromboembolism.