Mitral Regurgitation

Relevant physical signs

• Inspection
  • Scars, especially mitral valvotomy scar in left axilla
  • Implantable cardiac device (e.g. PPM for high-grade block with atrial fibrillation, implantable cardiac defibrillator for cardiomyopathy with EF < 30% causing functional MR)
  • Visible apex beat
• Hands
  • Stigmata of infective endocarditis (clubbing, Osler’s nodes – painful, Janeway lesions – painless)
• Pulse
  • Rhythm: typically MR is associated with atrial fibrillation
  • Character: in severe MR, pulse may be jerky (rapid upstroke with short duration)
  • Volume: often variable if the patient is in AF
• Conjunctival pallor (rare cases of valve haemolysis associated with infective endocarditis)
• Jugular venous pulsation
  • Elevated in right heart failure
  • Giant v waves (functional tricuspid regurgitation secondary to severe MR)
• Precordium
  • Inspect: implantable cardiac devices, valvotomy scars
  • Palpate
    • Apex beat
      • Thrusting – volume overloaded left ventricle
      • Double apex beat – palpable S3
      • In severe MR, may be displaced infero-laterally
    • Thrill over the mitral area (correlates to MR severity)
    • Right ventricular heave (pulmonary hypertension)
    • Thrill of tricuspid regurgitation (pulmonary hypertension with functional TR)
  • Auscultate
    • S1 – soft in severe MR
    • S2 – loud if MR is complicated by pulmonary hypertension
      • Widely-split in severe MR (large proportion of systolic volume flows into left atrium rather than aorta, resulting in aortic valve closing earlier)
    • S3 – this signifies rapid ventricular filling from increased pre-load. It is a marker of severe regurgitation, but only in the context of other clinical signs of severe MR
    • S4 – only if in sinus rhythm! Represents forceful atrial contraction against a non-compliant ventricle, and is a marker of severity of MR
    • Pan-systolic murmur loudest at the apex and radiating to the axilla, loudest in expiration
      • In functional MR, the murmur may be mid, late or pan-systolic
    • In severe MR, there may be a mid-diastolic murmur, which is a flow murmur signifying increased flow across the mitral valve
    • Tricuspid area for a pan-systolic murmur of functional tricuspid regurgitation – to differentiate from MR murmur, will usually be associated with giant v waves
    • Pulmonary area for Graham-Steell murmur of pulmonary regurgitation (pulmonary hypertension secondary to mitral regurgitation)
• Lung bases: crepitations of pulmonary oedema (may not be present if the patient is on diuretics)
• Pedal / sacral oedema for signs of right heart overload
• Complete examination by:
  • Looking at vitals chart, particularly temperature and blood pressure
  • Urine dipstick for evidence of microscopic haematuria (rheumatic heart disease)
  • Obtain an electrocardiogram (AF, left atrial hypertrophy / dilation)
  • Examine the abdomen for pulsatile hepatomegaly

Differential diagnosis of a pan-systolic murmur

• Mitral regurgitation (loudest at the apex in expiration, radiates to axilla)
• Tricuspid regurgitation (best heard at lower left sternal edge in inspiration, usually associated with v waves)
• Ventricular septal defect (usually very loud and harsh, heard all over the precordium but loudest at LLSE)
• Mitral valve prolapse (causes a late systolic murmur associated with an opening snap – may radiate up the left sternal edge as opposed to the axilla)

Causes of mitral regurgitation

• Rheumatic fever
• Previous mitral valvotomy
• Mitral valve prolapse
• Infective endocarditis
• Ischaemic heart disease
• Left ventricular dilation (functional MR due to displacement of the mitral valve annulus and chordae tendinae, causing mitral regurgitation)
• Mitral annular calcification
• Connective tissue disease
  • Systemic lupus erythematosus (Libman-Sachs endocarditis)
  • Rheumatoid arthritis
• Congenital disorders
  • Marfan’s syndrome
  • Ehlers-Danlos syndrome
  • Pseudoxanthoma elasticum
  • Osteogenesis imperfect

Causes of acute mitral regurgitation

• Acute rupture of chordae tendinae (post-myocardial infarction)
• Infective endocarditis
• Trauma

Clinical signs of severe mitral regurgitation

• Soft S1
• Widely-split S2
• S3
• S4, if in sinus rhythm
• Displaced apex beat
• Palpable thrill over mitral area
• Presence of a mid-diastolic murmur
• Pulmonary oedema
• Pulmonary hypertension (loud S2, right ventricular heave)
• Signs of right ventricular failure (raised JVP, dependent oedema)

Investigations

• Electrocardiogram
  • Rhythm: atrial fibrillation
  • Left atrial hypertrophy (bifid p waves in lead II if in sinus rhythm)
  • Left ventricular hypertrophy
  • Evidence of ischaemic heart disease (can cause MR)
• Chest radiograph
  • Double right heart border (left atrial enlargement)
  • Cardiomegaly
  • Pulmonary oedema
  • Prominent pulmonary arteries (pulmonary hypertension)
• Transthoracic echocardiogram
  • Confirm diagnosis of MR
  • Assess severity
  • Establish underlying mechanism (infective endocarditis, ischaemic MR, functional MR, rupture of papillary muscle, prolapse of one or two leaflets of the mitral valve)
  • Assessment of left ventricular function
  • Assessment of right ventricular function
  • Assessment of estimated pulmonary artery systolic pressure
• Coronary angiography
  • To exclude ischaemic heart disease as a cause for MR
  • To evaluate if CABG will be required at the time of potential mitral valve replacement

Management

• There is no indication for prophylaxis against infective endocarditis in native valve disease. The indications for prophylaxis against infective endocarditis are:
  • Previous episode of infective endocarditis
  • Prosthetic valves
  • Prosthetic material used for valve repair
  • Cyanotic congenital heart disease, not corrected
  • Corrected congenital heart disease within the last six months
  • Repaired congenital heart disease with residual defects near the prosthesis
• Atrial fibrillation
  • Requires rate control (choice between beta blocker, calcium channel antagonist, digoxin)
  • Anticoagulation to prevent thromboembolic disease
• Cardiac failure
  • Diuresis for congestive symptoms (spironolactone if class IV)
  • Angiotensin converting enzyme inhibitor for cardiac remodeling
  • Beta blockade to reduce myocardial oxygen demand
• Follow-up: six-monthly transthoracic echocardiogram

Indications for mitral valve replacement

• Symptomatic MR (NYHA class III or IV)
  • Class I: no limitation of physical activity
  • Class II: slight limitation of physical activity (dyspnoea, palpitations, fatigue with ordinary activity)
  • Class III: no symptoms at rest, but marked restriction in physical activity
  • Class IV: symptoms at rest
• EF < 60%
• LV end-systolic diameter > 45mm

Presentation

Sir, this patient has a grade 4/6 pan-systolic murmur heard loudest over the apex in expiration and which radiates to the axilla. This is most in keeping with mitral regurgitation. Clinically, it is at least moderate in severity: the apex beat is displaced, the first heart sound is soft, and the second heart sound is loud. This is associated with a right ventricular heave and the jugular venous pulse is elevated, signifying pulmonary hypertension with right heart overload. The pulse is irregular, which is in keeping with atrial fibrillation complicating the disease. I would expect the patient to be anti-coagulated, but I do not detect any overt signs of bleeding clinically. There are scattered crepitations at the lung bases, which signify pulmonary congestion secondary to mitral regurgitation. There is no scar to suggest previous mitral valvotomy. In summary, this patient has moderately-severe mitral regurgitation.