Cardiology · Valvular Heart Disease
The facts most likely to be tested
Chronic mitral regurgitation presents with a holosystolic murmur heard best at the cardiac apex that radiates to the axilla.
Acute mitral regurgitation often results from papillary muscle rupture or chordae tendineae rupture following an acute myocardial infarction.
The handgrip maneuver increases afterload, which increases the intensity of the mitral regurgitation murmur by forcing more blood back into the left atrium.
Chronic severe mitral regurgitation leads to left ventricular volume overload, resulting in eccentric hypertrophy and eventual left-sided heart failure.
Echocardiography is the gold standard diagnostic test to assess the severity of regurgitation and the ejection fraction.
Surgical mitral valve repair is preferred over mitral valve replacement to preserve left ventricular geometry and function.
Patients with symptomatic severe mitral regurgitation or asymptomatic patients with an ejection fraction ≤ 60% require surgical intervention.
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A 68-year-old male presents to the emergency department with acute onset of severe shortness of breath. He had an inferior wall myocardial infarction 4 days ago. On physical examination, he is tachycardic and tachypneic with bilateral crackles on lung auscultation. A new holosystolic murmur is heard at the cardiac apex that radiates to the axilla. His blood pressure is 90/60 mmHg.
What is the most likely diagnosis and the most appropriate next step in management?
Acute mitral regurgitation due to papillary muscle rupture; emergent echocardiography and surgical consultation.
The patient's history of recent MI combined with a new holosystolic murmur radiating to the axilla is classic for papillary muscle rupture, a life-threatening complication of MI.
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Etiology / Epidemiology
Primary MR is often due to mitral valve prolapse or rheumatic heart disease; secondary MR results from LV dilation.
Clinical Manifestations
Presents with a holosystolic murmur at the apex radiating to the axilla; apical thrill may be present.
Diagnosis
Transthoracic echocardiogram is the diagnostic test of choice; TEE is superior for surgical planning.
Treatment
Manage with afterload reduction (ACE inhibitors); surgical mitral valve repair is preferred over replacement.
Prognosis
Chronic MR leads to LV volume overload and eventual heart failure; monitor with serial echos.
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Epidemiology & Etiology
Primary MR involves structural valve damage, most commonly myxomatous degeneration (mitral valve prolapse) in developed nations. Rheumatic heart disease remains a leading cause globally. Secondary (functional) MR occurs due to LV remodeling or ischemia, where the valve leaflets are normal but fail to coapt.
Pertinent Anatomy
The mitral apparatus includes the leaflets, annulus, chordae tendineae, and papillary muscles. Dysfunction of any component, particularly papillary muscle rupture post-MI, leads to acute, severe regurgitation.
Pathophysiology
Regurgitation causes a volume overload state in the left atrium and left ventricle. The LV compensates via eccentric hypertrophy to maintain stroke volume. Over time, this leads to LV dilation, increased wall stress, and eventual systolic dysfunction.
Clinical Manifestations
Patients present with exertional dyspnea and fatigue. The classic finding is a holosystolic murmur heard best at the apex, radiating to the axilla. Acute MR presents with sudden pulmonary edema and cardiogenic shock. S3 gallop indicates significant volume overload.
Diagnosis
Transthoracic echocardiogram confirms the diagnosis and assesses severity. Transesophageal echocardiogram (TEE) is the gold standard for evaluating valve morphology and surgical candidacy. Key markers include regurgitant fraction >50% and effective regurgitant orifice area >0.4 cm².
Treatment
Asymptomatic patients are managed medically with ACE inhibitors or ARBs to reduce afterload. Avoid vasodilators in patients with hypotension. Surgical mitral valve repair is indicated for symptomatic patients or those with LVEF <60% or LV end-systolic diameter >40 mm.
Prognosis
Chronic MR progresses to atrial fibrillation and pulmonary hypertension. Patients require serial echocardiograms to monitor LV size and function to prevent irreversible myocardial damage.
Differential Diagnosis
Mitral Valve Prolapse: mid-systolic click
Tricuspid Regurgitation: murmur increases with inspiration
Aortic Stenosis: systolic ejection murmur at right upper sternal border
Ventricular Septal Defect: harsh holosystolic murmur with palpable thrill
Hypertrophic Cardiomyopathy: murmur intensity changes with Valsalva