Mitral Prolapse and Regurgitation
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Introduction
Mitral valve prolapse is one of the most common valvular abnormalities in the industrialized world. It is estimated to affect 3% or more of adults, most often young women. It can proceed to mitral regurgitation.
The Case of...
a simple case introducing clincial presentation and calling for a differential diagnosis to get students thinking.
Causes and Risk Factors
Causes of mitral regurgitation include:
- myxomatous (45%)
- postinflammatory scarring following rheumatic fever (40%)
- ischemic (10%) - LCX, RCA blockages can lead to papillary muscle ischemia
- endocarditis (3%)
Other causes include mitral leaflet disorders, rupture of chordae or papillary muscles, mitral annulus disorders, or primary mitral valve prosthetic disorders.
Pathophysiology
Myxomatous degeneration can lead to ballooning of the mitral leaflets, which can become thick and rubbery. Tendinous cords can become elongated, thinned, and occasionally ruptured.
Myxomatous degeneration is common in Marfan syndrome, caused by mutations in fibrillin-1.
Acute mitral regurgitation leads to pulmonary edema due to backflow through high LA pressure. Chronic mitral regurgitation leads to dilated LA, with normal pressure. Thus pulmonary edema decreases.
Signs and Symptoms
- history
- physical exam
History
Mitral prolapse is usually detected incidentally, but can cause serious symptoms in a small minority. These can include:
- dyspnea, orthopnea, PND
- fatigue
- angina
- hemoptysis
- depression, anxiety
Physical Exam
Examine under different loading conditions.
Mitral prolapse presents as a midsystolic click.
acute mitral regurgitation
- LV normal size but hyperdynamic
- loud S1
- systolic murmur; late or pan-systolic; loudest at apex, with potential radiation to axilla
- diastolic inflow rumble if severe
- S3 +/- thrill, can be present and may be the only abnormality
chronic mitral regurgitation
- pulse: brisk, low volume
- apex: hyperdynamic, laterally displaced (key)
- S1 soft or normal
- S2 wide split due to early A2
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
Diagnostic Imaging
Mitral valve prolapse is defined by echoradiography.
ECG:
- LA enlargement
- A fib
- LVH in 50% of people with severe MR
- RVH in 15%
- combined hypertrophy
CXR:
- increased LV
- much enlarged LA
Differential Diagnosis
Treatments
Mechanical problems can only be fixed surgically, with valvular repair or replacement.
Repair is better than replacement, if possible, as it is in 70-90% patients
- lower operative mortality (2-3% vs 2-7%)
- better outcome
- no anticoagulation needed
- LVEF preserved
Timing is difficult - don't rush into open heart surgery, but delays too long can reduce survival.
Indications include NYHA class III or IV
- EF <60% or above 60% but steadily dropping
- LVESD >45mm
minor criteria:
- any symptoms of heart failure
- flail mitral leaflet
- left atrial diameter above 45 mm
- atrial fibrillation
LV ejection fraction is the strongest predictor of outcome following surgery and should be assessed quantitatively suing MUGA or echo.
If EF <30%, medical management is best for now. Repair may be useful.
subacute bacterial endocarditis prophylaxis is not indicated and not normally done.
Consequences and Course
Mitral valve prolapse almost always has no ill effects, but in less than 5% of people, serious complications can arise:
- infective endocarditis
- mitral regurgitation
- stroke or other systemic infarct
- arrhythmias, with occasional sudden death
Mitral regurgitation can cause serious, life-threatening problems.
- systemic embolization due to atrial fibrillation, 2e to dilation
- pulmonary hypertension, right sided failure
Resources and References
Topic Development
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