Cardiology · Valvular Heart Disease
The facts most likely to be tested
Chronic aortic regurgitation presents with a diastolic decrescendo murmur best heard at the left sternal border with the patient leaning forward.
The physical exam reveals a wide pulse pressure leading to hyperdynamic pulses, often described as water-hammer or Corrigan pulse.
Severe chronic aortic regurgitation causes eccentric left ventricular hypertrophy due to chronic volume overload.
Acute aortic regurgitation is a surgical emergency typically caused by aortic dissection or infective endocarditis.
The Austin Flint murmur is a mid-diastolic rumble heard at the apex caused by the regurgitant jet striking the anterior mitral valve leaflet.
Echocardiography is the gold standard for diagnosis, while cardiac MRI is indicated if echocardiographic images are suboptimal for assessing left ventricular volumes.
Surgical aortic valve replacement is indicated for all symptomatic patients or asymptomatic patients with an ejection fraction ≤ 55%.
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A 62-year-old male presents to the clinic complaining of progressive exertional dyspnea and palpitations. Physical examination reveals a bounding carotid pulse and a wide pulse pressure of 140/60 mmHg. Auscultation demonstrates a high-pitched, blowing diastolic decrescendo murmur heard best at the third intercostal space. A low-pitched mid-diastolic rumble is also noted at the cardiac apex. The patient has no history of fever or recent dental procedures.
What is the most likely mechanism for the mid-diastolic rumble heard at the apex?
Functional mitral stenosis caused by the regurgitant jet striking the anterior mitral valve leaflet (Austin Flint murmur).
This vignette tests the recognition of the Austin Flint murmur, a classic finding in severe aortic regurgitation where the regurgitant jet interferes with mitral valve opening.
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Etiology / Epidemiology
Chronic AR is often due to rheumatic heart disease or bicuspid aortic valve; acute AR is a surgical emergency caused by aortic dissection or infective endocarditis.
Clinical Manifestations
Presents with wide pulse pressure and Austin Flint murmur; look for Water-hammer pulse and de Musset sign.
Diagnosis
Transthoracic echocardiogram is the gold standard; surgery is indicated for LVEF < 50% or severe symptoms.
Treatment
Chronic management uses ACE inhibitors or nifedipine; beta-blockers are contraindicated in acute AR due to loss of compensatory tachycardia.
Prognosis
Left ventricular dilation leads to heart failure; annual monitoring required for asymptomatic patients with LVEF > 50%.
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Epidemiology & Etiology
Chronic AR is frequently secondary to rheumatic heart disease, bicuspid aortic valve, or connective tissue disorders like Marfan syndrome. Acute AR is a life-threatening emergency typically resulting from aortic dissection (Type A) or infective endocarditis causing leaflet destruction.
Pertinent Anatomy
The aortic valve fails to close completely during diastole, allowing blood to flow from the aorta back into the left ventricle. This creates a volume overload state, leading to compensatory left ventricular eccentric hypertrophy and eventual dilation.
Pathophysiology
Regurgitant flow increases end-diastolic volume, causing the left ventricle to dilate to maintain stroke volume via the Frank-Starling mechanism. Over time, the ventricle reaches its limit of compliance, leading to increased end-diastolic pressure and pulmonary congestion. In acute cases, the non-compliant ventricle cannot accommodate the sudden volume, leading to rapid pulmonary edema and cardiogenic shock.
Clinical Manifestations
Patients exhibit a wide pulse pressure (systolic minus diastolic > 40 mmHg). Physical exam reveals a high-pitched, blowing, decrescendo diastolic murmur at the left sternal border. Classic signs include Water-hammer pulse (bounding), de Musset sign (head bobbing), and Quincke pulse (nail bed capillary pulsations). Acute AR presents with sudden dyspnea, hypotension, and rapid hemodynamic collapse.
Diagnosis
Transthoracic echocardiogram is the diagnostic test of choice to assess valve morphology and ventricular function. Cardiac catheterization is reserved for preoperative evaluation. Surgical intervention is indicated for symptomatic patients or those with LVEF < 50% or end-systolic diameter > 50 mm.
Treatment
Chronic AR is managed with ACE inhibitors or dihydropyridine calcium channel blockers (e.g., nifedipine) to reduce afterload. Beta-blockers are strictly contraindicated in acute AR as they prevent the necessary compensatory tachycardia. Surgical aortic valve replacement is the definitive treatment for severe symptomatic disease.
Prognosis
Untreated severe AR leads to irreversible left ventricular dysfunction and heart failure. Asymptomatic patients with normal function require serial echocardiograms every 6–12 months to monitor for LVEF decline.
Differential Diagnosis
Aortic Stenosis: systolic ejection murmur with pulsus parvus et tardus
Mitral Stenosis: mid-diastolic rumble with opening snap
Pulmonic Regurgitation: Graham Steell murmur, usually secondary to pulmonary hypertension
Aortic Dissection: tearing chest pain radiating to the back
Infective Endocarditis: fever, new murmur, and positive blood cultures