Demonstrating the mechanism of electrical alternans in cardiac tamponade: “the swinging heart”

A 52‐year‐old man presented with fever and progressive dyspnoea. He had a respiratory rate of 36 breaths per minute, pulse rate 126 beats per minute, blood pressure 96/56 mmHg, raised jugular venous pressure with prominent x‐descent, significant pulsus paradoxus and distant heart sounds. Echocardiography revealed a large pericardial effusion with tamponade (Figure, A, red arrow), a “swinging heart” (Figure, A and B, and Supporting Information), and electrical alternans (Figure, E, alternate white and yellow arrows). Electrical alternans is characterised by alternating QRS amplitude on surface electrocardiogram. It typically occurs in cardiac tamponade due to the swinging motion of the heart. However, it may be seen in Wolff–Parkinson–White syndrome, ventricular tachycardia, accelerated idioventricular rhythm, and supraventricular tachycardia. Immediate pericardiocentesis of haemorrhagic fluid relieved his tamponade (Figure, C and D). The analysis of the fluid suggested possible tubercular aetiology, hence he was given antitubercular treatment.