[Electric signs of experimental pericarditis]

Utilizing 25 mongrel dogs, we studied the electrocardiographic (direct and surface records) and lesional changes induced by the instillation of 7.5% Methyl-salicilate solution and by the acute pericardial effusion produced by the injection of 50 ml of mixed blood-saline solution. Ten unipolar records on the parietal pericardium, right atrium, right and left intraventricular unipolar leads and cavitary tensional curves were obtained. Light and electronic microscopy changes were analized in 11 cases. The anatomical data showed pericardial hemorrhage and injury of 3 to 6 lines of superficial myocytes. On ECG (direct and surface leads) an elevation of RST-T was observed from chest and pericardial unipolar leads and depressed ST in the chambers of the heart, and from a VR and a VL. RST-T displacement as well as developing negative T waves were outstanding on the rigth chest leads (V5R to V3R), on the left (V4-to V6), in DII, DIII, aVF and abdominal leads. A straight RST-T elevation with notch at the juntional point was observed, suggesting atrial injury. No alteration of intrinsic or intrinsicoid velocity were apparent. All of these signs, together with depressed ST in leads aVR and unipolar right chamber leads are signs which suggest pericardial involvement. The P wave became bimodal on the middle chest leads and +/- on right chest leads indicating atrial damage (68%). Thus, an RST-T upward displacement in V3R-V4R, can be a sign of pericarditis as well as right ventricular infarction. The pressure curves were altered only by artificial acute effusion: RA = 20.6, pericardial sac 20.6 and late diastolic of RV = 13.2.(ABSTRACT TRUNCATED AT 250 WORDS)