Aprotinin use during deep hypothermic circulatory arrest for type A aortic dissection and cesarean section in a woman with preeclampsia

Abstract

The patient was a 110-kg, 34-year-old, G2P1A0 woman at 34-weeks gestation with a past medical history significant for congenital mitral valve prolapse and preeclampsia during a previous pregnancy, which necessitated a cesarean section at that time. She was admitted to an outlying hospital at 34-weeks gestation for treatment of preeclampsia. Her initial symptoms included hypertension and peripheral edema. Initial therapy included labetalol and methyldopa. On the seventh day of hospitalization, she awoke with dyspnea and crushing substernal chest pain. Transthoracic echocardiography at this time revealed a dissection flap in the ascending aorta and aortic arch. The patient was transferred directly to the authors’ hospital for an emergent cesarean section and repair of the aortic dissection. On presentation, the patient was extremely anxious, although pain free. Her blood pressure was 150/90 mmHg, pulse 100 beats/min, and respiratory rate 18 breaths/min. Initial laboratory values revealed a hemoglobin of 10.2 g/dL, a platelet count of 187,000/mL3, sodium 138 mEq/L, potassium 4.1 mEq/L, blood urea nitrogen 4 mg/dL, and creatinine 0.5 mg/dL. Coagulation studies revealed a prothrombin time of 12.4 seconds and a partial thromboplastin time of 25 seconds. Rapid-sequence induction of general anesthesia was carried out with sodium thiopental (4 mg/kg) and succinylcholine (1.5 mg/kg). Anesthesia was maintained with a balanced technique consisting of isoflurane, fentanyl (27 g/kg), midazolam (0.18 mg/kg), and pancuronium (25 mg). Before induction, a 20gauge left radial arterial catheter was placed. A right internal jugular venous central catheter was placed after induction of general anesthesia. Before surgical incision, transesophageal echocardiography confirmed the presence of a dissection of the ascending aorta involving the aortic valve, aortic arch, and descending aorta (Figs 1 and 2). Mild aortic insufficiency was also noted. The remainder of the transesophageal echocardiography examination revealed that the mitral, pulmonic, and tricuspid valves were normal. There were no segmental wall motion abnormalities noted. Four minutes after abdominal incision (42 minutes after induction of general anesthesia), a female infant was delivered by cesarean section with Apgar scores of 5 at 1 minute and 8 at 5 minutes. The infant was taken to the neonatal intensive care unit (ICU) and was discharged home on the fourth postoperative day. After delivery, the uterine incision was closed and hemostasis obtained. Twenty units of oxytocin were administered intravenously, and uterine tone was evaluated. Hemostasis was deemed adequate, and the abdominal wound was left open and packed with sponges to facilitate examination after cardiopulmonary bypass. Sodium beef lung heparin (300 U/kg) was then administered intravenously. The kaolin activated coagulation time (ACT) was then determined to be greater than 500 seconds. An aprotinin test dose (1 mL) was administered intravenously with no adverse reaction. An intravenous loading dose of 2 million units of aprotinin was then administered, 2 million units added to the pump prime, and an intravenous infusion started at 500,000 U/h. After sternotomy, cardiopulmonary bypass was initiated using a 15F arterial inflow cannula in the femoral artery and a 2-stage venous cannula placed through the right atrial appendage. Direct examination of the aorta showed a dissection at the level of the tubular sinus extending circumferentially to the right coronary ostia. The patient was actively cooled to a nasopharyngeal temperature of 17.1°C. Deep hypothermic circulatory arrest (DHCA) was initiated to facilitate replacement of the underside of the aortic arch and ascending aorta. Reimplantation of the right coronary ostia was also performed. Total circulatory arrest time was 34 minutes and total aortic crossclamp time 64 minutes. The patient was rewarmed to a temperature of 36.5°C and subsequently weaned from cardiopulmonary bypass. No inotropes were required after cardiopulmonary bypass. The total cardiopulmonary bypass time was 162 minutes. Surgical hemostasis was obtained, and protamine (250 mg) was administered intravenously to reverse the effects of heparin. The ACT returned to normal, and the sternum was closed *B.A. Murphy, D.A. Zvara, L.H. Nelson, and N.D. Kon