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with preoperative renal dysfunction. However, there is little evidence that this management improves postoperative renal function.

Intraoperative care

Cardiopulmonary Bypass

Anticoagulation is achieved with normal doses of heparin (300 U/kg) prior to cardiopulmonary bypass. Some patients with hepatic congestion or prolonged hep-arin administration preoperatively may have reduced plasma concentrations of antithrombin III and therefore may be resistant towards the effects of heparin. Heparin resistance is promptly corrected by administration of antithrombin III (1000-1500 U), although giving 1-2 units of fresh frozen plasma is an acceptable alternative. The aorta is cannulated in the normal fashion. The pulmonary artery catheter is withdrawn into the superior vena cava, and the superior and inferior vena cava are cannulated separately to allow excision of the heart. After initiation of car-diopulmonary bypass, the aorta, pulmonary artery, and atria are transected and the heart is excised, leaving a cuff of the right and left atrium to allow anastomosis to the donor right and left atrium. This is followed by anastomosis of the aorta and pulmonary artery, and after rewarming the patient is weaned from cardiop-ulmonary bypass.

Weaning from Cardiopulmonary Bypass

The patient is weaned from cardiopulmonary bypass using the same principles as those for any cardiac procedure. Thus, heart rate and rhythm, volume status, contractility, and afterload are optimized. This frequently requires the administration of isoproterenol, dopamine, or dobutamine. The choice of agent is mainly determined by the systemic vascular resistance. The volume management is guided by the filling pressures and TEE. Direct observation of the heart in the surgical field reveals right ventricular function. After weaning, the pulmonary artery catheter is readvanced into the pulmonary artery. Appropriate monitoring will allow the anesthesiologist to determine whether weaning from cardiopulmonary bypass is successful. Adequate circulation results in a cardiac index of > 2 L/min/m2 and a SvO2 of > 70%.

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