Heart Valve Disease for USMLE Step 1
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Heart Valve Disease for the USMLE Step 1 Exam
Types of Heart Valve Disease
Heart valve disease includes stenosis (narrowing) and regurgitation (backflow) of the four heart valves: aortic, mitral, tricuspid, and pulmonic. This review focuses on the most common valve disorders and their key features.
Aortic Stenosis
- Etiology:
- Calcific Degeneration: Common in elderly patients.
- Bicuspid Aortic Valve: Congenital defect leading to premature calcification.
- Rheumatic Fever: Rare in developed countries, but often involves multiple valves.
- Pathophysiology: Narrowing of the aortic valve creates left ventricular (LV) outflow obstruction, increasing LV pressure and leading to LV hypertrophy.
- Clinical Presentation:
- Dyspnea, angina, and syncope on exertion.
- Heart Sound: Crescendo-decrescendo systolic murmur best heard at the right upper sternal border, radiating to the carotids.
- Pulsus Parvus et Tardus: Weak and delayed carotid pulse.
- Diagnosis:
- Echocardiogram: Confirms stenosis severity and LV hypertrophy.
Aortic Regurgitation
- Etiology:
- Valve Disease: Bicuspid valve, infective endocarditis, or rheumatic disease.
- Aortic Root Disease: Aortic dissection or connective tissue disorders like Marfan syndrome.
- Pathophysiology: Backflow of blood into the LV during diastole causes LV volume overload, leading to eccentric hypertrophy.
- Clinical Presentation:
- Dyspnea and fatigue, often with exertion.
- Heart Sound: Decrescendo diastolic murmur best heard at the left sternal border.
- Widened Pulse Pressure: Bounding pulses; may see findings like Quincke’s pulse (nailbed capillary pulsation).
- Diagnosis:
- Echocardiogram: Assesses severity of regurgitation and LV function.
Mitral Stenosis
- Etiology:
- Rheumatic Fever: Most common cause, leading to thickening and fusion of the mitral valve leaflets.
- Pathophysiology: Narrowing of the mitral valve obstructs blood flow from the left atrium to the LV, increasing left atrial pressure and risk of atrial fibrillation.
- Clinical Presentation:
- Dyspnea, orthopnea, and paroxysmal nocturnal dyspnea (PND).
- Heart Sound: Low-pitched, rumbling diastolic murmur at the apex, preceded by an opening snap.
- Diagnosis:
- Echocardiogram: Determines stenosis severity and left atrial size.
Mitral Regurgitation
- Etiology:
- Primary: Mitral valve prolapse (MVP), infective endocarditis.
- Secondary: LV dilation from ischemic or non-ischemic cardiomyopathy.
- Pathophysiology: Backflow of blood into the left atrium during systole causes left atrial dilation and LV volume overload.
- Clinical Presentation:
- Dyspnea and fatigue with exertion.
- Heart Sound: Holosystolic murmur best heard at the apex, radiating to the axilla.
- Diagnosis:
- Echocardiogram: Assesses regurgitation severity and LV function.
Tricuspid and Pulmonic Valve Disease
- Tricuspid Regurgitation:
- Typically secondary to right ventricular (RV) dilation from pulmonary hypertension or left-sided heart disease.
- Presents with a holosystolic murmur at the left sternal border, increasing with inspiration (Carvallo’s sign).
- Pulmonic Stenosis:
- Often congenital, with a systolic murmur best heard at the left upper sternal border.
- May cause RV hypertrophy and is treated with balloon valvuloplasty if severe.
- Pulmonic Regurgitation:
- Often due to pulmonary hypertension.
- Usually asymptomatic; managed by treating the underlying cause.
Key Points
- Aortic Stenosis:
- Presents with exertional dyspnea, angina, and syncope; diagnosed with echocardiography showing LV hypertrophy and valve narrowing.
- Aortic Regurgitation:
- Symptoms include dyspnea and fatigue; key findings include a diastolic murmur and widened pulse pressure.
- Mitral Stenosis:
- Commonly due to rheumatic fever, presenting with dyspnea and a rumbling diastolic murmur with an opening snap.
- Mitral Regurgitation:
- Presents with exertional dyspnea and holosystolic murmur; caused by mitral valve prolapse, endocarditis, or secondary to LV dilation.
- Tricuspid and Pulmonic Valve Disease:
- Tricuspid regurgitation often secondary to RV dilation; pulmonic stenosis is usually congenital.