Mitral Regurgitation: Pathogenesis, Symptoms & Management

Mitral Regurgitation

Valvular Heart Disease

Definition: Backflow of blood from the left ventricle (LV) into the left atrium (LA) during systole. Rheumatic disease is the principal cause in developing countries; elsewhere, degenerative causes predominate.

Mitral regurgitation

1. Pathogenesis

The hemodynamic effect depends heavily on the onset.

Chronic Mitral Regurgitation
Gradual volume overload leads to:

➢ LA Dilatation: Keeps LA pressure relatively low.
➢ LV Dilatation: Slow process; few symptoms initially.

Acute Mitral Regurgitation
Sudden volume overload leads to:

➢ Normal LA Compliance: Cannot stretch rapidly.
➢ Rapid Pressure Rise: Immediate pulmonary oedema.

2. Causes & Etiology

A. Mitral Valve Prolapse (Floppy Valve)

Common cause of mild MR. Associated with Marfan syndrome or degenerative myxomatous changes.

Valve bulges into Atrium (Systole)

↓

Mid-Systolic Click

↓

Late Systolic Murmur

Associated Features: Often benign arrhythmias, atypical chest pain, and a very small risk of TIA/Stroke.

B. Functional & Other Causes

➢ Functional MR: Due to LV dilatation (Dilated Cardiomyopathy or CAD) distorting papillary muscles/chordae.
➢ Endocarditis: Important cause of acute MR.
➢ Post-Procedural: Following valvotomy or valvuloplasty.

3. Clinical Features

Physical Signs

➢ Pulse: AF common (due to atrial dilatation).
➢ Apex Beat: Displaced (LV dilatation), active and rocking (volume overload).
➢ Auscultation:
  • Soft S1: Valve doesn't close properly.
  • Pan-systolic Murmur: Apical, radiates to axilla (may have thrill).
  • Loud S3: Due to rapid filling flow.
  • Short Mid-Diastolic Murmur: Due to increased forward flow.

Summary of Features

Feature	Details/Cause
Symptoms	Breathlessness, Fatigue, Palpitations (AF), Oedema/Ascites (Right heart failure).
Signs (Left Heart)	Apical Pan-systolic murmur, Thrill, Displaced Apex, S3, Basal Crepitations.
Signs (Right Heart)	RV Heave, Raised JVP, Ankle Oedema (Late stages).

4. Investigations

➢ Echocardiography (Pivotal): Assesses severity (Doppler), valve structure, and LV function.
➢ ECG: P-mitrale (LA enlargement) or Atrial Fibrillation.
➢ CXR: Enlarged LA/LV, pulmonary venous congestion.
➢ Cardiac Cath: Indicated if surgery considered. Shows large 'v' waves in wedge pressure trace.

5. Management

Medical Management

Aim: Reduce Afterload & Control Rhythm

➢ Vasodilators: ACE Inhibitors / ARBs (reduce afterload/regurgitant fraction).
➢ Diuretics: For fluid overload.
➢ AF Control: Digoxin & Anticoagulants.

Surgical Management

Indications: Worsening symptoms, progressive cardiomegaly, or deteriorating LV function.

Mitral Valve Repair
Treatment of Choice. May use Annuloplasty Ring.

Valve Replacement
If repair is not feasible.

⚠ Surgical Dilemma: If LV dilatation is the cause (not result) of MR, surgery may worsen function as the ventricle loses the low-pressure "pop-off" into the atrium.

MedicosHelper