SURGICAL-TREATMENT FOR ANEURYSMS OF THE DESCENDING AORTA USING TEMPORARY PERFUSION BY A CENTRIFUGAL PUMP - CLINICAL ANALYSIS OF 33 CASES

Since 1987, 33 patients have undergone surgery at Kobe University Hosp ital for aneurysm of the descending aorta using left heart bypass with a heparin-coated centrifugal pump and heparin-coated tubes. Sixteen p atients had true aneurysms of the descending thoracic aorta, 7 had tho racoabdominal aneurysms, and 10 had aortic dissection (DeBakey's Type III). Heat exchangers and oxygenators were not included in the bypass circuit in any of the cases. Perfusion time was from 42 to 205 min (av erage 90 min). Left heart bypass was established with 1 mg/kg of syste mic heparinization in 5 cases, 0.5 mg/kg in 5 cases, and 0 mg/kg in 23 cases. There were no complications such as perioperative embolism, ac idosis, or hypothermia. During aortic cross-clamping, the arterial pre ssure of the lower extremity was maintained above 70 mm Hg, but there was no relationship between the distal perfusion pressure and bypass f low. The urine output during left heart bypass was related to the dist al perfusion flow by centrifugal pump. Of 23 patients who underwent by pass with less than 40 ml/kg/min of distal perfusion flow, 7 showed tr ansient renal dysfunction postoperatively, and 1 developed postoperati ve renal failure. The other patients who were bypassed with over 40 ml /kg/min of pump flow stayed in the normal range of renal function. Pos toperative paresis occurred in 2 patients, who were also perfused with less than 40 ml/kg/min of bypass flow. It could be concluded that lef t heart bypass by centrifugal pump is safe and acceptable as a circula tory support in the surgical treatment of aneurysm of the descending a orta. In addition, during such assistance, more than 40 ml/kg/min of p erfusion flow is recommended to maintain the distal circulation and to prevent ischemic renal damage and spinal cord injury.