Delayed Tamponade After Transseptal Puncture: Focus on the Mechanism of a Rare But Life-Threatening Complication.

Transseptal puncture (TSP) has evolved into a key step during various percutaneous interventions. We present a case of delayed TSP-related tamponade, which underscores the importance of vigilance even during commonly performed procedures. TSP is safest when the puncture is through the fossa ovalis, with increased risk in patients with certain anatomic features (eg, small or diminutive fossa). Despite standard precautions, this TSP resulted in delayed cardiac tamponade >2 hours postpuncture. An understanding of the embryologic anatomy of the interatrial septum and imaging is crucial for minimizing complications and ensuring optimal outcomes.