A 73-year-old man diagnosed with severe aortic regurgitation by transthoracic echocardiography was referred to our hospital. Quadricuspid aortic valve was diagnosed on preoperative transesophageal echocardiography. We performed aortic valve replacement with a bioprosthetic valve. In the operation, the accessory cusp was found to be located between the right coronary and noncoronary cusps, and the cusps had multiple fenestrations near the commissures.

The patient, a female in her 60s, was under anticoagulant therapy with direct oral anticoagulant (DOAC) for persistent atrial fibrillation. She suddenly presented with chest pain, prompting her emergency admission to our medical facility. Subsequently, she received a diagnosis of acute aortic dissection (Stanford A) and was referred to our department for urgent surgical intervention. The administration of Andexanet Alfa was initiated in the emergency department due to the markedly elevated risk of life-threatening hemorrhage associated with DOAC medications. Surgery was approached through a median sternotomy, and 20,000 units of unfractionated heparin were administered intravenously during cardiopulmonary bypass (CPB) preparation. However, the activated clotting time (ACT) exhibited suboptimal extension at 181 s (pre-heparin ACT: 124 s), necessitating supplementary heparin infusion. This resulted in the cumulative administration of 80,000 U of heparin before achieving an ACT exceeding 400 s. Suspecting heparin resistance, we maintained an ACT greater than 400 s during CPB through the continuous administration of nafamostat within the CPB circuit. Subsequently, we performed graft replacement of the ascending aorta, weaning from the CPB was smooth, hemostasis was good, and the operation was completed. The patient's postoperative recovery remained uneventful, leading to her discharge on the 11th day following the surgery. Notably, there were no instances of major bleeding or thromboembolic events during her hospitalization. Preoperative oral DOAC therapy presents a critical and potentially life-threatening concern due to its association with heightened intraoperative and postoperative bleeding risks. Currently, a Factor Xa inhibitor reversal agent, Andexanet Alfa (Ondexa®)，is available and expected to contribute to the treatment of critical bleeding in patients taking DOAC. However, further research is warranted to accumulate knowledge regarding its efficacy and optimal utilization. In this case, we present an instance of acute aortic dissection with heparin resistance following the preoperative administration of a DOAC antagonist, contributing to the existing literature on this matter.