Acute pulmonary embolism.

A55-year-old man with a history of paroxysmal atrial fibrillation, hypertension, and stroke presented to the emergency room with the acute onset of shortness of breath. He had previously been prescribed warfarin therapy, which was self-discontinued 3 months before admission. A baseline ECG made 6 months before admission showed normal sinus rhythm with a heart rate of 80, an axis of 215°, and nonspecific T-wave abnormalities (Figure 1A). Physical examination at admission showed a respiratory rate of 35, pulse of 130, and blood pressure of 130/90 mm Hg. The heart had a regular rhythm with a normal S1, loud P2, 21 right ventricular (RV) heave, and a 2/6 holosystolic murmur at the left lower sternal border. The left calf was enlarged compared with the right, with increased warmth and tenderness. The ECG on presentation depicted sinus tachycardia with a heart rate of 133, a rightward axis shift, the McGinn and White pattern (S1Q3T3) associated with clockwise rotation of the heart, an incomplete right bundle branch block, and nonspecific ST segment and T-wave abnormalities (Figure 1B). CT of the chest showed multiple bilateral low attenuation filling defects in the lobar and segmental pulmonary arteries, as well as a large fusiform filling defect in the main pulmonary artery bifurcation consistent with pulmonary emboli (Figure 2A). On transthoracic ECG, the RV was severely dilated and dysfunctional (Figure 2B) with diastolic flattening of the interventricular septum consistent with RV pressure overload (Figure 2C, arrowheads). Pulmonary artery pressure was estimated at 50 mm Hg. On short axis view, the main pulmonary artery was visualized with a large thrombus at the bifurcation into the left and right pulmonary arteries (Figure 2D). The patient received intravenous thrombolytic therapy with tissue plasminogen activator. He tolerated the medication and showed a significant improvement in his cardiopulmonary status. A repeat ECG on the second hospital day revealed normal sinus rhythm with a heart rate of 96, an axis of 25°, and nonspecific T-wave abnormalities (Figure 1C). The incomplete right bundle branch block and the prominent S1Q3T3 pattern were no longer present. A follow-up ECG demonstrated resolution of the RV dilatation and dysfunction and absence of the pulmonary artery clot. The patient was treated with intravenous heparin and discharged on warfarin without complications.