A healthy 28-year-old woman presented for evaluation of supraventricular tachycardia. She has had short-lived, sudden-onset palpitations since she was in high school. The echocardiogram did not show any structural heart abnormalities. She was taken for an electrophysiology study. Upon insertion of catheters (Figure 1), blue arrow, right atrium; black arrow, right ventricular apex; yellow arrow, coronary sinus; white arrow, ablation) via the right femoral vein, it was found that the catheters entered into the right atrium via the Superior Vena Cava (SVC). Venography revealed a persistent azygous vein opening into the SVC (Video 1). Electrophysiology study eventually revealed typical atrioventricular nodal reentrant tachycardia, which was successfully ablated. Interruption of the Inferior Vena Cava (IVC) with azygous continuation is a rare congenital anomaly in which the IVC is interrupted below the hepatic vein and venous return is via the azygous vein into the SVC [1,2]. This can cause procedural obstacles during right heart catherization, IVC filter placement, temporary pacing lead placement, and, as in this case, electrophysiology study. Awareness of this anomaly can aid in planning to avoid complications and/or delay of needed surgery.

Author Contributions: AK, conception of report, drafting of manuscript, final approval; AB, conception of report, critical revision of manuscript, final approval.

Conflicts of Interest and Source of Funding: The authors received no specific funding for this work. The authors have no conflicts of interest to declare.

Disclosures: None.

Funding: None.