Abstract
In the case described, necrosis of the atrial musculature led to rupture of the chamber. This was overlooked for 4 days until the patient died of ventricular rupture. This unusual complication of atrial infarction may be amenable to surgical repair if recognised in time. The high gain recording of P waves in the presence of AV block made it possible to evaluate the P wave changes during atrial infarction: (1) changes in the configuration and width of the P wave, probably resulting from intra-atrial conduction defect; (2) depression of the PR segment (0.04 to 0.07 mV); and (3) a previously unrecorded convexity in the first portion of the PR segment, in the leads in which the depression of the PR segment was observed.