The floppy mitral valve. Study of incidence, pathology, and complications in surgical, necropsy, and forensic material.

Abstract

SUMMARY In the study of 1984 routine hospital necropsies the mitral valve was examined from the left atrium in the intact heart with a pressure head of water in the left ventricle. The valve was graded from grade 0 (normal) to grade 4: grade 1, expansion of a small part of one cusp only; grade 2, over one-third of the posterior cusp or one-half of the anterior cusp expanded, with intact chordae; grade 3, ruptured chordae; grade 4, chordal fusion to ventricular wall. The frequency ofgrade 2 to 4 floppy valves rose with age with an overall incidence of 3 9 per cent in men and 5-2 per cent in women. Grade 1 floppy valves have no clinical significance. Grade 2 floppy valves were found to be associated with auscultatory signs but often only contributed to cardiac failure or were coincidental findings. Grade 3 and 4 floppy valves were direct causes of death from bacterial endocarditis and/or severe mitral regurgitation.The surgical series of floppy valves showed that chordal rupture was the event which most commonly made operation necessaryin middle age:in a minority this was caused bybacterial endocarditis. Dilatation of the annulus was an important contributory factor but can produce significant mitral regurgitation without chordal rupture, particularly in inherited connective tissue disorders such as the Marfan syndrome.Forensic necropsies confirm that sudden death occurs in patients with floppy valves. The majority have grade 3 or 4 floppy valves and presumably significant mitral regurgitation. A minority have minimal valve involvement and the mechanism of death is unexplained.The exact magnitude ofthe risk for any patient with a floppy valve of developing bacterial endocarditis, or chordal rupture leading to significant mitral regurgitation, or of dying suddenly, is not known but must be very low considering the frequency of the valve lesion.The essential pathology of the floppy mitral valve is weakening of the central fibrous core allowing cusp expansion and chordal elongation to occur. The weakness ofthe collagen is in part genetically determined, in part age related. Identical changes occur in the tricuspid valve, and in the aortic root, leading to aortic regurgitation. Similar pathological changes are well recognised in other mammals, particularly the aged dog.

The Relationship Between Echocardiographic Features of Mitral Valve and Elastic Properties of Aortic Wall and Beighton Hypermobility Score in Patients With Mitral Valve Prolapse

“…33) In another study, the concordance between inadequate production of type III collagen and echocardiographic findings of MVP in patients with type IV Ehler-Danlos syndrome have suggested that this collagen abnormality may be the responsible factor in patients with this syndrome. 34) Abnormalities of collagen have been found in myxomatous or floppy valves of patients with MVP [11][12][13] that coincide with those identified in skin biopsies of patients with hypermobility syndrome 9) leading to the suggestion of a common pathogenetic mechanism of abnormal production or maturation of collagen. 14) Several clinical observations have led to the speculation that primary MVP syndrome represents a generalized disorder of connective tissue.…”

“…6) In the following years, a high incidence of MVP has been reported in patients with benign joint hypermobility syndrome (BJHMS), 7,8) which, like MVP, is inherited mainly as a sex-influenced dominant trait. 9,10) Abnormalities of collagen have been found in myxomatous or floppy valves of patients with MVP [11][12][13] that coincide with those identified in skin biopsies of patients with hypermobility syndrome 9) leading to the suggestion of a common pathogenetic mechanism of abnormal production or maturation of collagen. 14) However, there have been a few studies on the relation between the echocardiographic features of mitral valves [anterior mitral leaflet thickness (AMLT), 15) maximal leaflet displacement (MLD), 7) degree of mitral regurgitation (DMR)], elastic properties of the aortic wall [index of aortic systolic (AOSDI) and diastolic diameters (AODDI), index of aortic stiffness (IAOS) and aortic distensibility (AOD)], and Beighton hypermobility score (BHS) in MVP patients with BJHMS.…”

Age-related valvular regurgitation: a study by pulsed Doppler echocardiography.

“…The grade of these changes is in part genetically determined and in part age related. 12 16 Therefore, multivalvular regurgitation of little or no clinical significance can be expected to occur in older subjects. The purpose of this study was to investigate the prevalence of valvular regurgitation in the aged by pulsed Doppler echocardiography.…”

Mitral valve prolapsus as a rare cause of sudden cardiac death case presentation and review of literature

“…Klinik çalışmalarda mitral kapak prolapsusunun prevalansı %2,4 olarak bildirilirken (2) otopsi serilerinde insindansı %18'e kadar çıkmaktadır (3 Nishimura ve ark. (6) 237 hastalık uzun dönem (ortalama 6,2 yıl) bir takip çalışmasında, redundan mitral kapakların ani ölüm, infektif endokardit, serebral emboli gibi ölümcül komplikasyonlar için muhtemel bir risk oluşturduğunu tanımlamışlardır.…”