Mitral regurgitation

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Mitral regurgitation (MR), mitral insufficiency or mitral incompetence is a disorder of the heart in which the mitral valve does not close properly when the heart pumps out blood. It is the abnormal leaking of blood from the left ventricle, through the mitral valve, and into the left atrium, when the left ventricle contracts, i.e. there is regurgitation of blood back into the left atrium.[1] MR is the most common form of valvular heart disease.

Causes:

  1. Rheumatic heart disease.
  2. Mitral valve prolapsed.
  3. Myocarditis.
  4. Dilated cardiomyopathy.
  5. Infective endocarditis.
  6. Hypertensive heart disease.
  7. Damage to papillary muscle.
  8. Myocardial infarction.

Pathophysiology: With each contraction blood regurgitate into left atrium from left ventricle through incompetence vlve. So more blood comes into left ventricle in next phases, causing volume overload. To compensate this left ventricle works more, as a result left ventricle hypertrophy occurs. Thus pressure inside the left atrium is increased. But it is not like the MS.

Clinical features:

Symptoms:

Dyspnoea (due to pulmonary venous congestion)
Fatigue (due to low cardiac output)
Palpitation (due to AF, increased stroke volume)
Oedema, ascites (due to right heart failure)z
Signs:
Atrial fibrillation/flutter.
Cardiomegaly: Displaced hyperdynamic apex beat.
Apical pansystolic murmur ± thrill.
Soft S_1 apical S_3.
Signs of pulmonary venous congestion (crepitations, pulmonary oedema, effusions)
Signs of pulmonary hypertension and right heart failure.
Investigations:
ECG:
Left arterial hypertrophy (if not in AF)
Left ventricle hypertrophy.
Chest X-ray:
Enlarged LA and LV.
Pulmonary venous congestion.
Pulmonary oedema (if acute)
Echo:
Dilated LA and LV.
Dynamic LV (unless myocardial dysfunction predominates)
Structural abnormalities of mitral valve (e.g. prolapsed)
Doppler: Detects and quantify regurgitation.
Cardiac catheterization:
Dilated LA dilated LV, mitral regurgitation.
Pulmonary hypertension.
Coexisting coronary artery disease.

Management:

[A] Medical management:

Diuretics (e.g. Thiazide/Frusemide).
Vasodilators (e.g. Captopril).
Digoxin- If atrial fibrillation is present.
Anticoagulants-If atrial fibrillation is present.
Antibiotic prophylax is against:
Infective endocarditis (e.g. erythromycin)
Rheumatic fever (lifelong penicillin)

[B] Surgical management: in severe cases

Mitral valve repair (ring or ruptured chordate)
Mitral valve replacement: by tissue/mechanical valve.

Reference:

  1. Davidson’s Principles and practice of Medicine, 21st edition.
  2. Wikipedia the free encyclopedia.

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