ELECTRICAL-CURRENT PATHS IN ACUTE PERICARDITIS

The electrocardiographic changes accompanying pericarditis consist of ST elevation in most of the leads of the 12-lead electrocardiogram. Th e source of this ST elevation is thought to be local inflammatory chan ges in the epicardium underlying the inflamed pericardium. The current from this area of ST elevation must return to some unaffected region of the heart and this should be associated with a region of ST depress ion. This current path from the external epicardial surface has been p ostulated to flow back into the endocardium through the great vessels and atria. To test this hypothesis, 18 patients with pericarditis were studied by body surface potential mapping and inverse epicardial pote ntial distributions were computed. The resultant maps were compared to those of normal people and patients with acute anterior infraction. E picardial maps from patients with pericarditis showed a region of curr ent flow into the heart over the great vessels and atria in all 18 pat ients. This pattern was not seen in normal patients or infarction pati ents and was consistent with the mechanism resulting in ST elevation i n pericarditis being one of current flowing from the epicardium out in to the thorax and back into the heart through the great vessels and at ria.