Multiform Ventricular Ectopic Rhythm

Six patients whose standard electrocardiograms showed multiform ventricular ectopic rhythm were studied. All patients had advanced organic heart disease and a significant intraventricular conduction defect (left bundle branch block in five and right bundle branch block plus left anterior hemiblock in one). The ventricular arrhythmia was generally resistant to antiarrhythmic therapy. Five of the six patients died after 2 to 16 months from the period of observation from terminal heart failure. None died suddenly. The ventricular arrhythmia did not seem to be directly related to mortality in any patient. Critical analysis of several long rhythm strips in each case revealed that discharge from multiple ventricular parasystolic foci shared in the multiform ventricular activity. The concurrent discharge of a minimum of three parasystolic foci and a maximum of six foci was found in the same case with a total of 24 parasystolic foci in the six patients. There was a remarkable constancy of the QRS configuration of all parasystolic foci over periods of observation of up to 16 months. However, 22 out of 24 parasystolic rhythms showed significant variation in the apparent rate of discharge in records obtained on different occasions and this was not related to the rate of the dominant rhythm or the administration of drugs. Fourteen parasystolic foci showed evidence of exit block, some of which were examples of a rapid parasystole with a high degree of exit block. The study suggests that multiform ventricular ectopic rhythm may, in part, be due to the concurrent discharge of multiple parasystolic foci.