Mitral Valve Prolapse
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Direct answer
Mitral valve prolapse is systolic billowing of one or both mitral leaflets more than 2 mm above the annular plane, usually from myxomatous degeneration, and it is a common cause of mitral regurgitation. Its characteristic auscultatory finding is a mid-systolic click followed by a late systolic murmur, and both shift with posture and manoeuvres. Most patients are asymptomatic, and the main concerns are regurgitation, endocarditis and arrhythmia.
What you must remember
- Diagnosis: echocardiography shows leaflet displacement above the mitral annulus in the parasternal long axis view; it affects a few per cent of the population.
- Click and murmur: a mid-to-late systolic click followed by a late systolic murmur at the apex, not an early ejection click.
- Valsalva and standing: reduce ventricular volume, so the click moves earlier and the murmur lengthens; squatting and handgrip do the reverse.
- Associations: Marfan syndrome and Ehlers-Danlos syndrome, both reflecting myxomatous connective tissue.
- Barlow disease: redundant, bileaflet prolapse with more severe regurgitation and a higher risk of ventricular arrhythmia.
- Complications: mitral regurgitation, infective endocarditis, chordal rupture, ventricular arrhythmias and, rarely, sudden death or stroke.
- Surgery: repair is preferred over replacement; indications include symptomatic severe regurgitation or left ventricular dysfunction.
- Prophylaxis: routine antibiotic prophylaxis is not indicated for prolapse alone; prior endocarditis and prosthetic valves are the main indications, per current guidance.
Turning a click into a diagnosis
A 24-year-old woman with recurrent palpitations and atypical chest pain has a mid-systolic click at the apex that is heard mainly on standing, followed by a late systolic murmur. Her echo shows the leaflets billowing above the mitral annulus, and the posterior leaflet looks thickened.
The diagnosis rests on connecting three observations, each of which changes management.
- Click timing: Ventricular volume sets the click, so standing or Valsalva moves it earlier.
- Murmur length: The murmur lengthens during the same manoeuvres, because regurgitation begins sooner in systole.
- Echo confirmation: The echo confirms prolapse and measures regurgitation, leaflet thickness and any chordal rupture.
- Asymptomatic patients: Trivial regurgitation is reassured, and endocarditis prophylaxis follows current guidance rather than the valve alone.
- Significant regurgitation: Serial echocardiography is used, and the timing of surgery depends on symptoms and ventricular function.
Arrhythmia risk is higher with a thick or redundant posterior leaflet, and that echo feature guides further assessment.
Where the examiner tests the click
The click is the usual trap, and three related confusions recur.
- Trap: reading every click as aortic or pulmonary stenosis. Correct: an early systolic click signals stenosis, while the mitral click is mid-to-late systolic and moves with posture.
- Trap: confusing the mitral click with the hypertrophic murmur. Correct: the hypertrophic murmur also increases with standing and Valsalva, so echocardiography is the single most specific test.
- Trap: confusing Barlow disease with uncomplicated prolapse. Correct: severe regurgitation, bileaflet billowing and sudden arrhythmia point to Barlow.
- Trap: missing the connective tissue clue. Correct: a tall, thin patient with a mid-systolic click and a dilated aortic root suggests Marfan syndrome, and the aortic root must be measured.
Frequently asked questions
What is the auscultatory finding in mitral valve prolapse?
Mitral valve prolapse produces a mid-to-late systolic click followed by a late systolic crescendo murmur at the apex. The click moves earlier on standing or Valsalva, and the murmur lengthens with these manoeuvres.
How do Valsalva and squatting change the findings in mitral valve prolapse?
In mitral valve prolapse, Valsalva and standing reduce ventricular volume, moving the click earlier and lengthening the murmur. Squatting and handgrip move the click later and shorten the murmur.
What is Barlow disease?
Barlow disease is a form of mitral valve prolapse with redundant, bileaflet billowing. It causes more severe regurgitation and carries a higher risk of ventricular arrhythmia than uncomplicated prolapse.
When is mitral valve surgery indicated in prolapse?
Mitral valve surgery is indicated for symptomatic severe regurgitation, or for severe regurgitation with left ventricular dysfunction or dilatation even when asymptomatic. Repair is preferred over replacement wherever it is feasible.
Which syndromes are associated with mitral valve prolapse?
Marfan syndrome and Ehlers-Danlos syndrome are classic associations with mitral valve prolapse, because both involve weakened myxomatous connective tissue. Imaging the aortic root is part of the assessment in Marfan syndrome.