The role of the physical examination in the evaluation of patients with valvular heart disease is also considered in Chaps. 38 and 234; of electrocardiography (ECG) in Chap. 235; of echocardiography and other noninvasive imaging techniques in Chap. 236; and of cardiac catheterization and angiography in Chap. 237.
Mitral valve prolapse (MVP), also variously termed the systolic click-murmur syndrome, Barlow’s syndrome (Fig. 260-1), floppy-valve syndrome, and billowing mitral leaflet syndrome, is a relatively common but highly variable clinical syndrome resulting from diverse pathologic mechanisms of the mitral valve apparatus. Among these are excessive or redundant mitral leaflet tissue, which is commonly associated with myxomatous degeneration and greatly increased concentrations of certain glycosaminoglycans. MVP is the most common abnormality leading to primary mitral regurgitation (MR) (see Chap. 259).
Congenital or developmental mitral valve prolapse. Myxomatous thickening and prolapse of the mitral valve can occur in isolation in 2–3% of the general population, or may be associated with heritable collagen-vascular disorders and aortic root dilatation, such as in Marfan syndrome. Myxomatous degeneration of the valve predisposes to severe regurgitation and chordal rupture, and is a frequent indication for mitral valve repair or replacement. Prolapse can affect only one or both leaflets, to varying degrees. A. Three-dimensional transesophageal echocardiogram showing a myxomatous mitral valve from the left atrial en face aspect. There is billowing and prolapse of the entire middle scallop of the posterior leaflet. (Figure courtesy of Douglas C. Shook, MD, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital). B. The posterior leaflet of the mitral valve demonstrates marked prolapse and hooding in all segments and severe redundancy in this photograph taken from the vantage point of the left atrium. C. Opening the left heart reveals prominent mitral leaflet hooding (arrows). The chordae are focally thickened, but are not fused as would be the case in rheumatic valve disease. (Used with permission from JC Wu, RF Padera: Clinicopathologic correlates, in Atlas of Echocardiography, 2nd ed, SD Solomon [ed], E Braunwald [series ed]. Philadelphia, Current Medicine Group LLC, 2008. p 363.)
In most patients with MVP, the cause is unknown, but in some, it appears to be genetically determined. A reduction in the production of type III collagen has been incriminated, and electron microscopy has revealed fragmentation of collagen fibrils.
MVP is a frequent finding in patients with heritable disorders of connective tissue, including Marfan syndrome (Chap. 406), osteogenesis imperfecta, and Ehlers-Danlos syndrome. MVP may be associated with thoracic skeletal deformities similar to but not as severe as those in Marfan syndrome, such as a high-arched palate and alterations of the chest and thoracic spine, including the so-called straight back syndrome. Other associated features can ...