Potential Variations of Extremities and of Precordium in Pericarditis

Abstract

In pericarditis the most conspicuous abnormalities of the ventricular complex of the standard electrocardiogram are early displacement of the RS-T segment and subsequent inversion of the T-wave. It is the generally accepted view that these changes depend upon myocardial damage. 1-4

With a view to learning more about this problem the extremity and precordial potentials 5 were studied in 8 cases of pericarditis. The etiology of the pericarditis was rheumatic fever in 3 cases, uremia in 2, tuberculosis in 1, and gonococcus infection in 2.

In neither patient with uremia did the electrocardiograms vary after development of a friction rub. At necropsy, although both showed fibrinous exudate on the visceral pericardium, neither displayed a large effusion or subepicardial myocarditis.

In the remainder, regardless of etiology, the electrocardiographic abnormalities were similar both in the standard and in the special leads. During the first week of acute pericarditis, when RS-T was still elevated in Leads I and II, the potential of the right arm showed a negative displacement, and of the left arm a positive displacement of this segment. There was either no deviation of the RS-T or a slight variable one in the lead from the left leg. In the case of the precordial leads this segment was negative in the curve from the right sternal margin, positive or isoelectric in the remaining leads.

During the inscription of the T-wave the potential of the right arm was negative, the potential of the left arm and that of the left leg were variable. In leads from the right side of the sternum the T-wave was always negative and more or less fused with the preceding segment. In the remaining precordial leads it was positive, and in one patient distinctly notched.