Unusual Coexistence: Inferior Vena Cava Agenesis, a Free-Floating Right Atrial Thrombus, and Severe Pulmonary Embolism Successfully Treated with Tenecteplase

Abstract

Background: Inferior vena cava agenesis (IVCA) is rare, and its association with severe pulmonary embolism (PE) is exceptional. Case Presentation: A 56-year-old man with insulin-dependent diabetes but no major venous thromboembolic risk factors presented with repeated syncope and hemodynamic shock. He was tachycardic, hypoxemic, and hypotensive. Echocardiography showed a free-floating right atrial thrombus with severe right ventricular dysfunction. CT confirmed massive bilateral PE and revealed IVCA with azygos continuation. Management and Outcome: Because of persistent instability and the unavailability of alteplase, weight-adjusted tenecteplase was administered, followed by unfractionated heparin. The patient improved rapidly. Echocardiography at 24 hours showed complete disappearance of the thrombus and recovery of right ventricular function. Follow-up CT demonstrated reduced clot burden. Workup for thrombophilia was negative. The patient was discharged on oral anticoagulation and remained asymptomatic at follow-up. Conclusion: This case illustrates a rare presentation of IVCA revealed by life-threatening PE and supports considering off-label tenecteplase when no approved fibrinolytic agent is available.