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The past decade has seen a notable resurgence of interest in the systolic click-murmur syndrome. Previously regarded as extracardiac and benign, it is now clear that these auscultatory findings are central to a disorder characterized by abnormal systolic herniation (prolapse) of the mitral leaflets into the left atrium. Although it may be the result of diverse etiologies, the usual case represents an idiopathic, hereditary disorder of the valve leaflets with pathologic findings similar to those in Marfan's syndrome. The condition is very common and generally benign, and asymptomatic; however, a wide variety of clinical manifestations has been described, with a clinical picture at times indistinguishable from that of coronary artery disease. The small subset of patients at risk for malignant arrhythmias and sudden death has yet to be fully characterized. Although noninvasive techniques generally suffice for the diagnosis of MVP, left ventricular cineangiography is the definitive procedure. It remains for future studies in symptomatic and asymptomatic patients to define the relation between severity of MVP, its clinical manifestations, and its prognosis.

The +Gz tolerance of asymptomatic aircrew with mitral valve prolapse (MVP) who had advanced Lown grade ventricular ectopy (multiformed or paired premature ventricular contractions and ventricular tachycardia) during +Gz-stress testing was investigated. The +Gz tolerance to an aeromedical centrifuge stress testing protocol revealed that these individuals had slightly lower +Gz tolerance for each of the different types of +Gz profiles, with the gradual onset of +Gz while using an anti-G straining maneuver (GOR-S) tolerance being significantly lower (p less than 0.05). As a subgroup of a larger group of individuals with MVP, these MVP individuals with advanced ventricular ectopy had an increased incidence of +Gz-induced loss of consciousness and motion sickness. The advanced ventricular ectopy occurred before, during, and after +Gz stress; however, there was a tendency for the ectopy to occur in the post +Gz stress period. The post +Gz stress period is a period of high parasympathetic (vagal) tone, and these findings may indicate that these individuals are in some way sensitive to high vagal tone. Acceleration stress testing is a valuable tool in the aeromedical evaluation of asymptomatic individuals desiring to fly fighter aircraft. Advanced ventricular ectopy not seen in other clinical testing (treadmill and ambulatory monitoring) occurred in these individuals. The current results suggest that these individuals with MVP and advanced ventricular ectopy are not currently prime candidates for flying fighter aircraft, not only because of the ventricular ectopy, but because of decreased +Gz tolerance and susceptibility to +Gz-induced loss of consciousness.

The left ventricular cineangiograms of 22 asymptomatic, apparently healthy male aviators without noninvasive (echocardiographic or auscultatory) evidence of mitral valve prolapse were reviewed and compared with those of 12 men with noninvasive evidence of mild mitral valve prolapse. The maximal protrusion of the posterior mitral valve leaflet superior and posterior to a line perpendicular to the long axis of the left ventricle at end-systole was measured from the right anterior oblique left ventricular cineangiogram by repeated observation of left ventricular inflow. The values were 7.5 +/- 1.6 mm in patients without mitral valve prolapse and 11.2 +/- 3.4 mm in patients with mitral valve prolapse (mean +/- 1 standard deviation). This measurement did not exceed 11 mm in any patient without prolapse. It is concluded that: 1) with meticulous attention to angiographic landmarks of the left ventricular inflow area, the limits of normal systolic posterior mitral leaflet motion can be defined; and 2) systolic motion outside these limits constitutes a quantitative criterion for the angiographic diagnosis of mitral valve prolapse.