eMedicine Specialties > Emergency Medicine > Cardiovascular
Mitral Valve Prolapse
Updated: Dec 22, 2008
Introduction
Background
Mitral valve prolapse (MVP) can occur in a multitude of disorders and, in most instances, it reflects a normal variant rather than a single disease process.
Despite years of research, the symptomatology and significance of MVP remain controversial. It was termed the disease of the decade in the 1980s, but now some consider it an interesting finding of dubious importance. Initial studies that reported associated symptoms of MVP as chest pain, dyspnea, anxiety, and panic, were probably flawed by recruitment bias. Recent studies imply that the incidence of MVP previously was overestimated by inaccurate echocardiographic diagnostic criteria and that associated symptoms, other than palpitations, are uncommon.1
Despite this, patients with MVP are at risk for endocarditis, stroke,2 mitral regurgitation (MR), mitral valve replacement (MVR) surgery,3 and sudden death.
Pathophysiology
A myxomatous degeneration from collagen dissolution leads to excess mucopolysaccharides in the middle spongiosa layer of the mitral valve leaflets, resulting in stretching of the leaflets and the chordae tendineae.
Mitral valve prolapse (MVP) occurs when the left ventricular (LV) size is small in comparison to an enlarged mitral annulus, leaflets, or chordae tendineae, and it can be induced in healthy women with typical body habitus following dehydration that is reversed with rehydration. MVP resolves during pregnancy and following weight gain in anorexic patients.
Recent studies have shown that abnormalities of elastic fibers found in floppy mitral valves are related to genetic variants in fibrillin, one of the components of the microfibrils, as well as elastin and collagen I and II.4
A constellation of abnormalities (eg, increased sensitivity to adrenergic stimuli, increased catecholamines, abnormal beta-receptors, increased atrial natriuretic factor, renin-aldosterone dysregulation, decreased intravascular volume, magnesium deficiency)5 has been thought to lead to chest pain, dyspnea, fatigue, dizziness, near-syncope symptoms, and anxiety in a subset of patients with MVP.6,7
Cardiac manifestations include supraventricular arrhythmias, palpitations, mitral regurgitation, bacterial endocarditis, and sudden death. Chest pain may not be more common in patients with MVP than in the general population, and it may be attributed to myofascial syndromes, hyperventilation, coronary spasm, esophageal dysmotility, or gastroesophageal reflux.8
Mitral valve prolapse can result in cerebrovascular ischemia, which may be related to abnormal platelet activity or protein C or S deficiencies.
Frequency
United States
Mitral valve prolapse (MVP) can be identified by echocardiography in 3-4% of the general population, and it is identified in 7% of autopsies.
International
The worldwide incidence of MVP is similar to that in the United States.
Mortality/Morbidity
- In general, mitral valve prolapse (MVP) is a benign disorder, but it may account for the majority of isolated cases of mitral regurgitation (MR), 90% of cases of ruptured chordae tendineae, 40% of strokes in young patients, and 10-15% of cases of endocarditis.
- Those with structural abnormalities (ie, thickened, deformed, or redundant mitral valve leaflets) are more likely to suffer complications (eg, progressive MR, endocarditis, sudden death).
- Cases of MVP with a murmur and not just an isolated click have a general mortality rate that is increased by 15-20%.
Race
Prevalence is similar among different ethnic groups.9
Sex
- The female-to-male ratio is approximately 3:1.
- Men older than 45 years have twice the risk of MR and endocarditis.
Age
Age of onset is 10-16 years.
- Mitral valve prolapse (MVP) is uncommon before the adolescent growth spurt occurs. It usually is detected in young adulthood.
- Although MVP is considered congenital, echocardiographic findings typically are absent in newborns.
Clinical
History
- Mitral valve prolapse (MVP) usually is asymptomatic, nonprogressive, and benign.
- Palpitations occur in 40% of MVP cases. This percentage excludes palpitations due to withdrawal syndromes (eg, alcohol, sedatives), intoxications (eg, cocaine, amphetamine, phencyclidine), or medication exposures (eg, caffeine, sympathomimetic, anticholinergic).
- Chest pain and dyspnea previously were considered part of the MVP syndrome, but they are now felt to be no more common in cases of MVP than they are in the general population.10,1
- Although controversial, anxiety and panic disorders may be more common in patients with MVP than the general population.11
- Fatigue
- Syncope/presyncope10
- Orthostasis10
Physical
- Thin aesthetic body habitus with narrow anteroposterior diameter12
- Skeletal abnormalities (ie, pectus excavatum, straight back, kyphoscoliosis)
- Supernumerary nipples in Asian Indians
- Resting bradycardia and orthostatic hypotension
- Cardiac auscultation
- Apical, single or multiple, mid-to-late systolic clicks, which result from the tightening of the chordae tendineae or the redundant valve, can be heard.
- An apical mid-to-late systolic murmur of crescendo, decrescendo, or constant nature can be heard, and the murmur continues to be heard in S2.
- The click and the murmur change as the position changes (closer to S1 with diminished LV volume; closer to S2 with increased LV volume)
- In the supine position, the click is late (ie, close to S2), and the murmur is brief.
- In the standing position and during the Valsalva maneuver, the click is earlier (ie, close to S1), and the murmur is longer. This may identify a murmur that previously was not noted.
- In the squatting position, the click is later (ie, closer to S2), and the murmur is shorter. The click and the murmur may even disappear.
- The isometric handgrip exercise increases the intensity (ie, loudness) of the murmur without affecting the position.
- The murmur should be distinguished from that of aortic stenosis (ie, early systolic, at base); pulmonic flow murmur (ie, short and early systolic, diminishes with Valsalva maneuver); hypertrophic cardiomyopathy (ie, diminishes with squatting and intensifies with standing and Valsalva maneuver); and mitral regurgitation (ie, holosystolic murmur with S3, enlarged and displaced point of maximal intensity [PMI]).
- Mitral regurgitation
- Autonomic dysfunction - Decreased heart rate variability and parasympathetic tone13,14
- Neuroendocrine dysfunction
- Ehlers-Danlos syndrome findings (eg, joint hypermobility, abnormal striae, bruising, distensibility of skin)
- Osteogenesis imperfecta findings (eg, blue sclera)
- Marfan syndrome findings (eg, scoliosis, straight back, pectus excavatum, arachnodactyly, arm span greater than body height)
- Stickler syndrome findings (eg, kyphosis, scoliosis, mandibular hypoplasia, retinal detachment). Whether Stickler syndrome is associated with MVP is debatable.
Causes
Most cases of mitral valve prolapse are primary, idiopathic in nature, and expressed as an autosomal dominant trait that exhibits both sex- and age-dependent penetrance.15
- Connective tissue disorders
- Muscle disorders
- Duchenne muscular dystrophy
- Fragile X syndrome
- Mucopolysaccharidoses
- Myotonic dystrophy
- Congenital heart disease - Atrial septal defect (ASD)
- Ebstein anomaly
- Acquired heart disease
- Papillary muscle dysfunction (eg, ischemia, myocarditis)
- Cardiac trauma
- Post mitral valve surgery
- Rheumatic endocarditis
- Miscellaneous
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References
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Avierinos JF, Brown RD, Foley DA. Cerebral ischemic events after diagnosis of mitral valve prolapse: a community-based study of incidence and predictive factors. Stroke. Jun 2003;34(6):1339-44. [Medline].
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Berbarie RF, Roberts WC. Frequency of atrial fibrillation in patients having mitral valve repair or replacement for pure mitral regurgitation secondary to mitral valve prolapse. Am J Cardiol. Apr 1 2006;97(7):1039-44. [Medline].
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Bonow RO, Carabello B, de Leon AC, et al. ACC/AHA Guidelines for the Management of Patients With Valvular Heart Disease. Executive Summary. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Patients With Val. J Heart Valve Dis. Nov 1998;7(6):672-707. [Medline].
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La Vecchia L, Ometto R, Centofante P, et al. Arrhythmic profile, ventricular function, and histomorphometric findings in patients with idiopathic ventricular tachycardia and mitral valve prolapse: clinical and prognostic evaluation. Clin Cardiol. Oct 1998;21(10):731-5. [Medline].
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Further Reading
Keywords
mitral valve prolapse, MVP, endocarditis, bacterial endocarditis, stroke, mitral valve surgery, sudden death, supraventricular arrhythmias, palpitations, mitral regurgitation, MR, syncope, Marfan syndrome, polyarteritis nodosa, relapsing polychondritis, systemic lupus erythematosus, Stickler syndrome, pseudoxanthoma elasticum
osteogenesis imperfecta, Ehlers-Danlos syndrome type I, Ehlers-Danlos syndrome type II, Ehlers-Danlos syndrome type IV, polycystic kidney disease, Duchenne muscular dystrophy, fragile X syndrome, mucopolysaccharidoses, myotonic dystrophy, atrial septal defect, Ebstein anomaly, papillary muscle dysfunction
cardiac trauma, post mitral valve surgery, rheumatic endocarditis, Wolff-Parkinson-White syndrome, Von Willebrand disease


Overview: Mitral Valve Prolapse