AV node dysfunction in the mitral valve prolapse syndrome.

The mitral valve prolapse syndrome is associated with a variety of atrial and ventricular arrhythmias. A portion of these patients manifest bradyarrhythmias, which in turn, may be the cause of lightheadedness and syncope. Thie study details the clinical and electrophysiologic characteristics of seven patients with symptomatic mitral valve prolapse and AV node dysfunction. The electrophysiology study demonstrated either a prolonged AH interval or abnormal response to atrial pacing in six of seven patients. A significant proportion of these patients had abnormalities of sinus node function and distal His-Purkinje conduction in addition to AV node dysfunction. AV node dysfunction in symptomatic patients with mitral valve prolapse may be secondary to autonomic dysfunction of diffuse conduction system disease.