Relationship between the electrical (electrocardiographic) and mechanical (echocardiographic) events in Wolff-Parkinson-White syndrome.

Studies using epicardial mapping on patients with Wolff-Parkinson-White syndrome have demonstrated that the delta vector of the electrocardiogram is a detector of the location of at least one bypass tract. In order to relate the electrical activities (preexcitation) with the mechanical activity (septal and ventricular wall motion), echocardiographic strip-chart recordings were obtained in 22 patients with Wolff-Parkinson-White syndrome. Our studies indicated that in the majority of patients with Wolff-Parkinson-White syndrome, left ventricular and septal contraction is normal, suggesting that normal activation predominates and that the determinants of abnormal septal wall motion are (1) the location (right ventricular free lateral wall or septrum) and (2) the degree (duration of the QRS complex greater than 130 msec) of ventricular preexicitation.