Chronic juvenile AV nodal dysfunction associated with mitral valve prolapse.

The prevalence of atrioventricular (AV) conduction disturbances amongst patients with mitral valve prolapse is higher than may be expected by chance, thus implying the existence of a true association. The main clinical and electrophysiologic findings in 4 patients with mitral valve prolapse showing chronic AV conduction disturbances are presented. Supra-His localization, mild and variable degree of impairment, regression upon Atropine administration, apparent absence of progression, are common features of these disturbances. The most likely mechanisms considered are an AV node developmental abnormality or an AV nodal artery running in contact with the border of the mitral annulus and thus impaired by the abnormal dynamics of the mitral valve.