Background
Mitral valve prolapse (MVP), the most common anomaly of the mitral valve apparatus, occurs when one or both mitral valve leaflets excessively billows into the left atrium toward the end of systole. Mitral regurgitation (MR) develops in some patients with mitral valve prolapse, particularly those with more significant prolapse, when the valve edges fail to coapt. An extreme form of prolapse could include chordal rupture, in which the prolapsed mitral valve is flail. Mitral valves excised from patients with severe MR secondary to mitral valve prolapse have large leaflets and various histologic alterations.
Besides the symptoms attributable to the MR, various neuroendocrine and autonomic disturbances occur in some patients with mitral valve prolapse. In these patients, prolapse may be an epiphenomenon of the underlying autonomic or neurohumoral illness. The term mitral valve prolapse syndrome is often used to refer to the collection of these manifestations. However, in a significant proportion of patients, the mitral valve prolapse is trivial, and no such associated manifestations are present. In these patients, mitral valve prolapse constitutes an essentially benign condition.
Mitral valve prolapse syndrome was recognized as early as 1916, when Sir James MacKenzie described the soldier’s heart in spare, thin young men with great vasomotor instability, easy fatigability, breathlessness, and pain over the region of the heart. Kerley first described the syndrome in 1920, and Lincoln described the syndrome in 1928. In 1963, Barlow and colleagues made the first clinical diagnosis of the syndrome as it is known today. The advent of echocardiography led to further advances and formed the basis of current knowledge.
Idiopathic mitral valve prolapse may be congenital in some patients, but recognition may be delayed until adolescence or adulthood. Associated complicating issues include cardiac arrhythmia, heart failure secondary to severe MR (rare), and, occasionally, thromboembolic events. Familial cases are known and occur in an autosomal dominant pattern with variable penetrance and expression (familial mitral valve prolapse).