Small amount is common in the population, but clinically significant in 2%.
- Mitral valve prolapse (causes 50%).
- Rheumatic heart disease.
- Infective endocarditis.
- Papillary muscle rupture due to MI.
- Appetite suppressants.
Secondary causes (aka ‘functional’):
- LV dilatation due to IHD.
- Dilated cardiomyopathy.
- 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.
- Chest pain.
- LVF symptoms.
- Symptoms of AF (though this is commoner in mitral stenosis): palpitations and an irregularly irregular pulse.
- 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.
- Mitral regurgitation.
- Tricuspid regurgitation: louder on inspiration.
- VSD: usually younger patient and apex non-displaced.
Echo is diagnostic.
- P-mitrale if in sinus rhythm: bifid/broad P-wave due to large left atrium.
- Enlarged left ventricle and atrium: double right heart border.
- Valve calcification.
- Cardiac MRI, angiography, and catheterisation, if indicated.
- BNP may provide prognostic information.
- 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.
- 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.
- Structural changes: left ventricular and atrial enlargement, CHF.
- Pulmonary HTN.
- Infective endocarditis.
- 5 year mortality in severe asymptomatic MR: 20%.