Mitral Regurgitation

 

• Background

  Epidemiology

  Small amount is common in the population, but clinically significant in 2%.

  Causes

  Primary causes:

  • Mitral valve prolapse (causes 50%).
  • Calcification
  • Rheumatic heart disease.
  • Infective endocarditis.
  • Congenital
  • Papillary muscle rupture due to MI.
  • Appetite suppressants.
  • Trauma

  Secondary causes (aka 'functional'):

  • LV dilatation due to IHD.
  • Dilated cardiomyopathy.
  • HCM
  • Aortic regurgitation.

  Mitral valve prolapse

  • Common (5% of population) 'myxomatous' degeneration of valve in which thickened valve leaflet is displaced into left atrium during systole, usually causing slight regurgitation, and with a minority progressing to significant mitral regurgitation.
  • Can be standalone or part of a connective tissue (Marfan's, Ehlers Danlos) or heart disease (atrial septal defect, persistent ductus arteriosus, cardiomyopathy).
  • Asymptomatic, or causes palpitations and chest pain. Mid-systolic click or late systolic murmur on auscultation.

• Signs and symptoms

  Asymptomatic or:

  • SOB
  • Fatigue
  • Chest pain.
  • LVF symptoms.
  • Symptoms of AF (though this is commoner in mitral stenosis): palpitations and an irregularly irregular pulse.

  Signs:

  • Pansystolic murmur heard at apex, radiates to axilla.
  • Hyperdynamic apex beat.
  • Systolic thrill over apex.
  • Soft S1.
  • LVF signs: S3, crackles.

  Acute mitral regurgitation – e.g. due to infective endocarditis or papillary muscle rupture – can present with pulmonary oedema.

• DDx: Pan-systolic murmur

  • Mitral regurgitation.
  • Tricuspid regurgitation: louder on inspiration.
  • VSD: usually younger patient and apex non-displaced.

• Investigations

  Echo is diagnostic.

  ECG:

  • AF
  • P-mitrale if in sinus rhythm: bifid/broad P-wave due to large left atrium.
  • LVH

  CXR:

  • Enlarged left ventricle and atrium: double right heart border.
  • Valve calcification.

  Further tests:

  • Cardiac MRI, angiography, and catheterisation, if indicated.
  • BNP may provide prognostic information.

• Management

  Medical:

  • Manage AF and HF if present.
  • Manage acute MR as acute heart failure, with the addition of sodium nitroprusside to reduce afterload, and intra-aortic balloon pump if hypotensive.
  • 6-monthly follow up and annual echo if severe.

  Surgical:

  • Indications: symptomatic MR, acute severe MR (emergency), or MR complications such as LVF, new-onset AF, or pulmonary HTN. In MR secondary to ischaemic HF, surgery should only be done alongside planned CABG.
  • Procedure: open repair is 1st choice. Valve replacement or percutaneous repair are other options.
  • Anticoagulation: 3 months after valve repair or bioprosthetic replacement, lifelong after metallic replacement.

• Complications and prognosis

  Complications:

  • Structural changes: left ventricular and atrial enlargement, CHF.
  • Pulmonary HTN.
  • AF
  • Infective endocarditis.

  Prognosis:

  • 5 year mortality in severe asymptomatic MR: 20%.