Paroxysmal Atrial Fibrillation Originating From the Inferior Vena Cava: A Case Report and Literature Review

FIGURE 1. Electrocardiogram showing atrial flutter with atrial rate 280–290/min with variable atrioventricular conduction in the limb leads, the atrial wave displayed negative wave in inferior leads (II, III, and avF, black arrow). The precordial 6 lead rhythm strip shows termination of atrial flutter with a sinus beat (red asterisk), followed by four consecutive ectopic atrial beats at rate 250/min, which showed a narrow positive wave in lead V1 (red arrow). The first conducted beat occurred with the right brunch block, the second was blocked, the third conducted a with a narrow QRS, and the fourth was blocked. This followed by another sinus beat followed by the same atrial tachycardia/atrial flutter at a rate of 260/min. The ECG was recorded at a speed of 25 mm/s (x axis) and an amplitude of 10 mm/mV (y axis).

FIGURE 2. Surface and intracardiac electrocardiogram indicate the termination of atrial fibrillation, followed by a sinus beat (red asterisk); atrial fibrillation was triggered again by a premature atrial complex, which exhibited a negative P wave in inferior leads (II, III, and aVF) and a positive P wave in lead V1 (red arrow). The ECG was recorded at a speed of 100 mm/s. X axis, time line; y axis: gain. CS, coronary sinus; ECG, electrocardiogram.

FIGURE 3. (A) Activation map and electrograms. Activation mapping shows that the earliest activity was at the posteromedial wall of the inferior vena cava. The intracardiac electrocardiogram indicates rapid discharges from the inferior vena cava; some of them were conducted to the right atrium (IVC 9-10) and left atrium (CS). The red asterisk represents the electrical activation recorded by the electrode. The ECG was recorded at a speed of 100 mm/s. (B) Successful ablation site. Atrial fibrillation terminated immediately after radiofrequency ablation at the earliest activation site in the posteromedial inferior vena cava. The ECG was recorded at a speed of 25 mm/s. X axis, time line; y axis, gain. CS, coronary sinus; ECG, electrocardiogram; IVC, inferior vena cava; SVC, superior vena cava.