An electrocardiogram of a 72-year-old man who developed acute respirophasic pain in the left and central anterior chest plus fever (103 °F) (Figure 1). There are ubiquitous ST segment deviations (labeled ‘J’), right axis deviation (approximately 160 °), indicating posterior fascicular block right bundle branch block, late intrinsic deflection (in V1) with virtual Q waves in lead I and a definite Q wave in lead II as well as a decrease in r wave voltage from V5 to V6 (V6 resembles lead I). The patient had a typical triphasic pericardial rub, a small pericardial effusion and a small left pleural effusion. The electrocardiogram is classic for acute pericarditis because the PR segments (PRs) are deviated as well as the J points (ST takeoffs). The suggested Q waves in leads I and II are consistent with a lateral wall myocardial infarction as is the right axis deviation. Lead V1 is classic for right bundle branch block, which in the absence of congenital heart disease rarely has a right axis orientation (in right bundle branch block the QRS axis is determined by the first 80 ms of the QRS). The change from lead V5 to lead V6 is also suggestive of lateral infarct (although in the presence of right axis deviation, the position of lead V6 posterior to the other chest leads makes this only suggestive). The P waves are bifid, consistent with interatrial block (IAB) and the points of the P waves are more than 40 ms separated in leads V5 and V5; with the large negative component of the biphasic P wave in lead V1 (Ptf), this is consistent with left atrial enlargement (frequent with IAB). Lead III shows minimal ST-T changes, which is frequent with acute pericarditis.