Mitral regurgitation !
Mitral regurgitation is a leak of the mitral valve: with each beat some blood flows backward from the left ventricle into the left atrium.
Updated 2026-10-29
Structures involved
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- Mitral anterior leaflet
- Mitral posterior leaflet
- Chordae tendineae
- Left ventricle papillary muscles
- Left atrium
- Left ventricle
- Valve rings (fibrous skeleton)
- Pulmonary veins
- Circumflex artery
- Right coronary artery
In the clinical exam
- Cardiac auscultation: the areas and the order
- Murmurs: timing, grade, location and radiation
- Valve murmurs: the table to know
- Dynamic auscultation: Valsalva, squatting, standing and handgrip
In physiology
- Heart sounds and where they come from
- The ventricular pressure–volume loop
- Preload, afterload and contractility
- Murmurs and the hemodynamics of valve disease
- Physiology of pulmonary edema
Why it happens
- The myocardial infarct over time: what the pathologist sees from hours to months
- The heart wall, valves and conduction tissue
What it is
Backflow of blood from the left ventricle into the left atrium during systole because the mitral valve does not close properly.
Who gets it
One of the most common valve diseases in adults, increasing with age. In Colombia and Latin America rheumatic heart disease remains an important cause in younger people, alongside degenerative and ischaemic causes.
Causes
- Primary (degenerative): mitral valve prolapse and myxomatous disease, flail leaflet from chordal rupture
- Rheumatic heart disease
- Infective endocarditis with leaflet perforation
- Secondary (functional): left ventricular dilation from cardiomyopathy or ischaemia
- Acute: papillary muscle rupture after myocardial infarction
Risk factors
- Older age
- Previous rheumatic fever
- Myocardial infarction (especially inferior-posterior)
- Dilated or Chagas cardiomyopathy
- Connective tissue disorders such as Marfan syndrome
- Infective endocarditis
Pathophysiology
Part of each stroke volume goes backwards into the left atrium. In chronic disease the atrium and ventricle dilate to accommodate the volume load, keeping output for years until the ventricle fails. In acute disease the small, stiff atrium cannot adapt, so pressure rises suddenly into the lungs and causes pulmonary oedema.
Classification
- Primary (valve apparatus disease) vs secondary (ventricular disease)
- Acute vs chronic
- Severity: mild, moderate or severe by echocardiographic criteria
Symptoms and signs
- Often no symptoms for years
- Exertional breathlessness and fatigue
- Palpitations from atrial fibrillation
- Holosystolic (pansystolic) murmur at the apex radiating to the axilla
- Displaced apex beat and a third heart sound in severe chronic disease
- Mid-systolic click before the murmur in mitral valve prolapse
Diagnosis
- Clinical
- Suggested by the apical holosystolic murmur radiating to the axilla; the history looks for rheumatic fever, ischaemia and endocarditis.
- Tests
- ECG may show left atrial enlargement (P mitrale), atrial fibrillation or previous infarction. Natriuretic peptides help judge severity; blood cultures if endocarditis is suspected.
- Imaging
- Transthoracic echocardiography confirms the mechanism and grades severity, chamber size and ejection fraction. Transoesophageal echo plans repair; chest X-ray may show left atrial enlargement and pulmonary congestion.
Differential diagnosis
- Aortic stenosis
- Tricuspid regurgitation
- Ventricular septal defect
- Hypertrophic cardiomyopathy
- Mitral stenosis
Goal of treatment
Relieve symptoms, protect left ventricular function by intervening at the right time, and manage atrial fibrillation and heart failure.
Treatment
- Follow-up
- Regular clinical and echocardiographic follow-up of asymptomatic patients to time intervention.
- Medical
- Heart-failure drug classes (diuretics, ACE inhibitors or ARBs, beta-blockers) for secondary regurgitation; rate control and anticoagulation for atrial fibrillation.
- Surgical
- Surgical mitral valve repair (preferred when feasible) or replacement for severe symptomatic primary regurgitation or early ventricular dysfunction.
- Procedure
- Transcatheter edge-to-edge repair for selected high-risk patients.
- Acute
- Emergency surgery for acute regurgitation from papillary muscle or chordal rupture, with afterload reduction and mechanical support as a bridge.
Complications
- Heart failure
- Atrial fibrillation and stroke
- Pulmonary hypertension
- Infective endocarditis
- Irreversible left ventricular dysfunction
Prognosis
Mild to moderate disease is often stable for years. Severe chronic regurgitation leads to heart failure if left untreated; timely repair gives good long-term survival. Acute regurgitation after infarction has high mortality without urgent surgery.
Test yourself
Think of the answer, then tap the question to see it.
What is the typical murmur of mitral regurgitation?
A holosystolic (pansystolic) blowing murmur, loudest at the apex, radiating to the left axilla.
Which cause of acute mitral regurgitation follows myocardial infarction?
Papillary muscle rupture, usually the posteromedial muscle, which often has a single blood supply.
Why does acute mitral regurgitation cause pulmonary oedema quickly?
The normal-sized left atrium cannot dilate to absorb the volume, so pressure rises sharply into the pulmonary veins.
What sound precedes the murmur in mitral valve prolapse?
A mid-systolic click as the leaflet billows into the left atrium.
Which arrhythmia commonly complicates chronic mitral regurgitation?
Atrial fibrillation, from left atrial dilation.
Related conditions
- Myocardial Infarction (Heart Attack)
- Rheumatic heart disease
- Infective endocarditis
- Heart failure
- Atrial fibrillation
- Ventricular septal defect
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Mitral Regurgitation (StatPearls (NCBI Bookshelf), 2026).
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Representative model, for educational purposes only.
