Severe pulmonary embolism and evolution of tracings
67-year-old man followed for renal neoplasia, hospitalized for sudden onset dyspnea with arterial hypotension (SAP of 80 mmHg); the cardiac ultrasound showed a right ventricular dilatation with pulmonary arterial hypertension; the angioscanner confirmed the diagnosis of bilateral massive pulmonary embolism with right ventricular dilatation; this electrocardiogram was performed at entry;
Tracing recorded 2 hours after the initiation of fibrinolysis; slowing of the sinus rate (117 bpm); decrease in the size of the S wave in lead I; T-wave inversion in V3-V4;
The tracings of this patient allow to detail the electrical abnormalities observed during a pulmonary embolism and their evolution over time. In a pulmonary embolism, one can observe:
- a sinus tachycardia which is common but not obligatory (absent, for example, in patients receiving beta-blocking treatment or in the presence of a small embolus with no hemodynamic strain); the heart rate usually slows down rapidly within a few hours or days; the incidence of supraventricular rhythm disorders (atrial fibrillation preferentially) is approximately 10%;
- unlike the chronic cor pulmonale, changes in the morphology of the P-wave and the pulmonary P-wave pattern (increase in P-wave amplitude in lead II, rotation of the P-wave to the right of the frontal axis) are rare in pulmonary embolism;
- a discrete prolongation of the PR interval is exceptionally observed;
- changes in the pattern of the QRS-complexes are relatively frequent, early and transient (they disappear within a few hours to a few days); their detection sometimes requires comparison with previous or subsequent electrocardiograms; in addition to the S1Q3 pattern, one can observe:
- an incomplete right bundle branch block with a rSr' or rsR' pattern, possible notching of the upward branch of the S wave and modest widening of the width of the QRS; this modification is precocious and fleeting; the observation of a complete right bundle branch block reflects the presence of a massive pulmonary embolism;
- an often limited rotation of the axis in the clockwise direction (from the normal axis to the vertical axis);
- displacement toward the left of the QRS transition zone in precordial leads by the recoiling of the left ventricle posteriorly and to the left;
- repolarization disorders with inversion of the T-wave in leads III, V1, V2, V3 sometimes with an "ischemic" appearance (peaked and symmetrical T-waves, more or less deep); these modifications are sometimes more discreet, asymmetrical and limited to V1; the inversion of the wave T in right precordial leads is the most common electrical sign; it appears slightly delayed compared to changes in the QRS but persists longer (up to several weeks); the T-wave is often unequivocally negative in lead III (S1Q3D3 pattern) whereas it is rather weakly positive or biphasic in lead II; in left precordial leads, repolarization remains mostly normal even if negative T-waves can also be observed; the ST-segment is mostly isoelectric, although changes in the T-wave can sometimes be associated with an ST-segment depression and exceptionally with an elevation.
Inversion of T-waves in right precordial leads and/or in lead III is the most common of the electrical abnormalities (after sinus tachycardia) observed during pulmonary embolism; the occurrence of peaked and symmetrical T-waves is often later than the changes in the QRS-complex, although persisting longer.