title: Coexistence of ventricular parasystole and ventricular couplets: mechanism and clinical significance.
abstract: In 78 consecutive patients with uniform ventricular ectopic complexes and without heart disease, ventricular couplets were present significantly more often when the coupling interval of ventricular ectopic complexes was variable than when it was fixed (P less than 0.04). In 69 consecutive patients with couplets, the prevalence of a variable coupling interval was significantly greater than that of (55 versus 14 cases; P less than 0.001). Among 55 patients with a variable coupling interval, ventricular parasystole was probable in 38 and possible in 17 patients. These results suggest that the association between ventricular couplets and parasystole is not coincidental. Of several possible mechanisms responsible for this association reentry within the parasystolic focus or its vicinity is the most probable. This may explain the observation that the couplets are seldom followed by consecutive ventricular ectopic complexes or ventricular tachycardia. If this hypothesis is correct, the clinical significance of ventricular couplets in the presence of ventricular parasystole may be similar to that of single reentrant ventricular ectopic complexes.
mesh_terms: D004562:Electrocardiography; D006330:Heart Defects, Congenital / Q000503:physiopathology; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D009200:Myocardial Contraction; D013599:Systole