Abnormal Left Ventricular Contraction Revealed by Impedance Cardiograms and Arterial Tracings in Bundle Branch Blocks and Old Myocardial Infarcts

Abstract

Following the observation of an unusual pattern of the first derivative of the impedance cardiogram in cases of bundle branch block, a systematic study was performed both in normal controls and clinical cases. This graphic study was supplemented by the simultaneous recording of the first derivative of an arterial tracing, preferably the indirect aortic pulse at the suprasternal notch. These studies were performed in 70 subjects: 30 normal subjects, 14 cases of right bundle branch block, 14 cases of left bundle branch block, and 12 cases of old infarcts. Out of 30 normal subjects, only 2 old persons showed splintering of the main systolic wave. Both right and left bundle branch blocks had in common either a splitting of this wave in 2 peaks or multiple splintering; however, 4 cases in each type of bundle branch block had a normal pattern. Among old infarcts, 7 had a splitting, 3 had multiple splitting, and 2 had a normal pattern. The derivative of the arterial tracings showed a remarkable similar ity with that of the impedance cardiogram, revealing that abnormal left ventricular ejection (dyssynergy) was present in all 3 types of lesion. The first derivative of the impedance cardiogram was often more typical than that of the arterial tracings, because it had fewer secondary vibrations or artifacts. Thus, the former seems more sensitive to diagnosing left ven tricular abnormalities of contraction, even when the electrocardiogram is normal.