The Electrocardiogram in Large Pericardial Effusion: The Forgotten “P” Wave and the Influence of Tamponade, Size, Etiology, and Pericardial Thickness on QRS Voltage

Abstract

There are varying reports on the electrocardiogram in pericardial effusions. Some correlate low QRS voltage with tamponade and the size of the effusion while others do not. Low voltage also appears to vary with the etiology. There are no reports on the influence of pericardial thickness or changes in the P voltage. The authors studied 43 patients with large effusions of whom 26 had tuberculosis and the remaining had viral/idiopathic etiology. Pericardial thickness was measured at chest computed tomography. They found no correlation between the low QRS voltage and tamponade, size of the effusion, etiology, or pericardial thickness. Low voltage of the P wave and T-wave changes were more frequent than low QRS voltage.

Role of a 12‐Lead Electrocardiogram in the Diagnosis of Cardiac Tamponade as Diagnosed by Transthoracic Echocardiography in Patients With Malignant Pericardial Effusion

“…In our study, the malignancies commonly associated with PE are consistent with reports in the extant literature . Several ECG abnormalities have been associated with PE and cardiac tamponade . These include sinus tachycardia, PR‐segment depression, ST‐segment elevation, low QRS voltage, and electrical alternans.…”

“…These include sinus tachycardia, PR‐segment depression, ST‐segment elevation, low QRS voltage, and electrical alternans. Though electrical alternans is not consistently present in cardiac tamponade, it is very specific for this condition . Electrical alternans occurs due to a beat‐to‐beat variation of the myocardial electrical axis on account of a swinging motion of the heart inside a fluid‐filled pericardium .…”

“…Further, in the series reported by Levine et al, of the 50 consecutive patients who underwent pericardiocentesis for cardiac tamponade, only 36% of patients exhibited pulsus paradoxus and only 50% of the patients had a clinical suspicion of tamponade . Electrocardiogram abnormalities associated with PE and cardiac tamponade include low‐voltage ECG complexes, PR‐segment depression, low‐voltage P waves, and sinus tachycardia . One such finding very specific to cardiac tamponade is electrical alternans …”

Intraoperative Acute Cardiac Tamponade as a Result of Intracardiac Perforation Requiring Emergency Continuous Pericardiocentesis and Open Sternotomy: A Case Report and Literature Review of a Rare but Fatal Complication

“…The most sensitive TEE findings for pericardial tamponade are the presence of fluid within the pericardial sac and evidence of RA collapse while the most specific findings are LA collapse and paradoxical motion of the interventricular septum, commonly referred to as septal displacement or "septal bowing" [14]. An electrocardiogram (ECG) can also aid in establishing a diagnosis of cardiac tamponade classically presenting as tachycardia with diffuse low voltage and electrical alternans due to the anterior-posterior swinging of the heart within the fluid-filled pericardial sac [15]. Following rapid identification, the treatment of pericardial tamponade involves immediate hemodynamic and inotropic support with emergency pericardiocentesis, and if refractory, a pericardial window, and lastly, the only definitive treatment for permanent pericardial constriction, a surgical pericardiectomy [16].…”