Billowing, floppy, prolapsed or flail mitral valves?

Billowing, Floppy, Prolapsed or Flail Mitral Valves? JOHN B. BARLOW, MD, and WENDY A. POCOCK, MB FRCP of this (Fig. lB), which may range in severity from being marked and diffuse to mild and involving only 1 scallop or even part of a scallop,6 should be termed a billowing mitral leaflet (BML). This BML may produce a nonejection click, but mild BML may not be evident on echocardiography or cineangiocardiography. Conversely, BML sufficiently prominent to be demonstrated by these methods of investigation, may not always be detected on auscultation. If the BML progresses, disruption of leaflet edge apposition may ensue and MVP is the result (Fig. 1C). Once there is MVP, mitral regurgitation is inevitable and is reflected clinically by a mitral systolic murmur. Becausethe BML is more marked it may be demonstrated on echocardiography, but echocardiography, whether M-mode or 2-dimensional, detects systolic displacement of the body of a leaflet and not disengagement of leaflet edge coaptation. If the BML is extreme with very voluminous leaflets and elongated chordae, the term floppy is appropriate. MVP is almost always present with a floppy valve (Fig. 1D) and the mitral regurgitation is often

More than 2 decades ago the auscultatory features of a late systolic murmur and non-ejection systolic click were shown to originate at the mitral va1ve.i Left ventricular cineangiocardiography confirmed that late systolic murmurs were indicative of mild mitral regurgitation and demonstrated “massive dilatation,” “aneurysmal protrusion,” “billowing” or “ballooning” of the posterior mitral leaflet.2g3Later studies showed that the anterior leaflet was also involved. In 1966, Criley et al4 clarified the cineangiocardiographic appearances and introduced the term prolapse. Mitral valve prolapse (MVP) is now a widely used term regardless of whether the valve anomaly is anatomically mild, echocardiographically demonstrable, functionally normal or clinically silent. This has contributed to the general confusion, and it is now crucial for the terms billowing, floppy, prolapse and flail to be defined. Such definitions should be based essentially on the functional anatomic, or pathologic, characteristics of the mitral valve mechanism. Auscultatory, echocardiographic, cineangiocardiographic and other clinical features should then be correlated with the probable functional anatomy. It is, after all, the functional anatomy of the mitral valve mechanism that we attempt to assessby all invasive or noninvasive investigations. We recently expressed the view5 that the concept propounded by the French cardiac surgeon, Alain Carpentier, defines the essential differences between prolapse and billowing. In this context Carpentier restricts the use of the term prolapse to failure of the leaflet edges to appose normally. Such partial loss of apposition may occur with or without abnormal billowing of the bellies of the leaflets, and mitral regurgitation, albeit mild or even minimal, will inevitably result. This concept of prolapse implies that the valve function is abnormal which is, in fact, both appropriate and correct. Any cardiac valve, provided there is not a hole or a cleft in a leaflet, remains competent while there is sustained coaptation of the leaflet edges.Prevention of apposition may occur if 1 or more leaflets are fibrosed or retracted. If leaflets are normal in size or larger, failure of sustained apposition will result in prolapse. Based on Carpentier’s understanding of MVP, we consider that the following terms, which reflect normal and abnormal mitral valve functional anatomy, should clarify much of the current confusion. The normal mitral leaflets billow slightly, after closure, into the left atria1 cavity (Fig. 1A). Exaggeration

G

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FIGURE 1. Billowing (BML), floppy, prolapsed (MVP) and flail mitral valves. A, normal mitral valve showing papillary muscles, chordae tendineae and apposed leaflet edges. B, BML; the chordae are lengthened and the voluminous leaflets “billow” into the left atrium. In this and subsequent drawings, the positions of normal leaflets are superimposed with a stippled pattern. C, BML with MVP; the valve is incompetent. D, floppy valve with MVP. E, floppy valve and flail leaflet. Marked regurgitation is present. F, recent onset anular dilatation causes MVP with minimal BML due to loss of “keystone” effect. G, a ruptured minor chorda allows MVP without detectable BML. H, flail leaflet with mild BML.

From the Cardiovascular Research Unit, Department of Cardiology, University of the Witwatersrand and the Johannesburg Hospital, Johannesburg, South Africa. Manuscript received September 17, 1984, accepted September 24, 1984. Address for reprints: John B. Barlow, MD, Department of Cardiology, Johannesburg Hospital, Private Bag X39, Johannesburg, 2000 South Africa. 501

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holosystolic. Echocardiography will readily confirm the floppy leaflets but not the MVP. Progression of the MVP with a floppy valve or with a BML may result in ruptured, or at least grossly elongated, chordae and part of the leaflet will then be flail (Fig. 1E). Mitral regurgitation is now hemodynamically significant and the displacement of the leaflet edge is readily apparent on echocardiography. Thus, although there is overlap and the dividing margins are somewhat ill-defined at present, floppy is the extreme of marked BML and flail that of severe MVP. Expanding further on Carpentier’s concept of “prolapse,” MVP may occur with insignificant BML. This could result, for example, from rupture of a minor chord (Fig. 1G) as a result of infective endocarditis on a normal or near-normal mitral valve. Progression to flail, still without BML, could occur after rupture of a major chorda tendinea or with multiple chordal rupture (Fig. 1H). Functionally lengthened chordae due to papillary muscle dysfunction could also cause MVP, sometimes temporarily, without detectable BML. Another mechanism for MVP with only mild BML is recent onset anular dilatation (Fig. 1F). When the “keystone effect”7 of leaflet edge apposition is diminished, the chordae are subjected to greater tension, and MVP may supervene. In our experience, a principal cause of recent-onset anular dilatation without BML is acute rheumatic carditis. More widely recognized is the combination of a dilated anulus with either marked BML or floppy valve. Anular dilatation, voluminous leaflets and elongated chordae are the characteristic morphologic feature@ of the “floppy valve syndrome,“g with or without skeletal manifestations of the Marfan syndrome. A BML may be a result of a degenerative processlO (primary BML) or be secondaryll to other valvular or myocardial pathology (secondary BML). Irrespective of whether protrusion of leaflet scallops into the left atrium can be shown on echocardiography, a BML on its own is a functionally normal valve as far as not allowing incompetence is concerned. Primary BML,

whether identified by “echo only”r2 or by hearing an isolated nonejection click,lr may thus be regarded as a “variant of normal,” especially in asymptomatic subjects. When symptoms, electrocardiographic changes, arrhythmias or other features occur, the recognition of a syndrome is justified and for many years we have preferred “billowing mitral leaflet syndrome” to denote that common condition. When a BML is relatively more severe, leaflet edges fail to remain in apposition, mitral regurgitation supervenes and this is MVP. We emphasize that MVP should be detected on auscultation but that mitral regurgitation can only be confirmed, if this is believed necessary, on cineangiocardiography or possibly by Doppler ultrasound. Furthermore, whereas echocardiography may demonstrate the BML, it does not show the MVP until it is very severe or a leaflet flail. References

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Barlow JB, Pocock WA, Marchand P, Denny M. The significance of late systolic murmurs. Am Heart J 1963;66:443-452. Barlow JB. Conjoint clinic on the clinical significance of late systolic murmurs and nonejection systolic clicks. J Chronic Dis 1965;18:665-673. Barlow JB, Bosman CK. Aneurysmal protrusion of the posterior leaflet of the mitral valve. Am Heart J 1966;71:166-178, Criley JM, Lewis KB, Humphries JO, Ross RS. Prolapse of the mitral valve: clinical and cineangiocardiographic findings. Br Heart J 1966;28:488496. Barlow JB, Pocock WA. The mitral valve prolapse enigma-two decades later. Mod Concepts Cardiovasc Dis 1984;53:13-17. Roberts WC. Congenital cardiovascular abnormalities usually “silent” until adulthood: morphologic features of the floppy mitral valve, valvular aortic stenosis, discrete subvalvular aortic stenosis, hypertrophic cardiomyopathy, sinus of Valsalva aneurysm, and the Marfan syndrome. In: Roberts WC, ed. Congenital Heart Disease in Adults. Philadelphia: FA Davis, 1979:407453. Cobbs BW. In: Hurst JW, Logue RB, Schlant RC, Wenger NK, eds. The Heart. 3rd ed. New York: McGraw-Hill, 1974:874. Bulkley BH, Roberts WC. Dilatation of the mitral anulus. A rare cause of mitral regurgitation. Am J Med 1975;59:457-463. Read RC, Thai AP, Wendt VE. Symptomatic valvular myxomatous transformation (the floppy valve syndrome): a possible forme fruste of the Marfan syndrome. Circulation 1965;32:897-910. Barlow JB, Pocock WA, Obel IWP. Mitral valve prolapse: primary, secondary, both or neither? Am Heart J 1981;102:140-143. Barlow JB, Pocock WA. Mitral valve prolapse, the specific billowing mitral leaflet syndrome, or an insignificant nonejection systolic click. Am Heart J 1979;97:277-285. Oakley CM. Mitral valve prolapse: harbinger of death or variant of normal? Br Med J 1984;288:1853-1854.