THORACOABDOMINAL ANEURYSM REPAIR - LESSONS LEARNED ON A GENERAL VASCULAR-SURGERY UNIT

Purpose: Much has been learned in the past thirty years regarding the management of patients with thoracoabdominal aortic aneurysms (TAA), e specially from the seminal contributions of Crawford and associates at Baylor. As a result of the efforts of Dr. Crawford and a few others, the management of these patients has spread from those centers special izing in the care of patients with TAAs to institutions that perform a wide breadth of general vascular surgery. This change in settings mig ht be accompanied by a change in the morbidity and mortality expected with the repair of TAAs, and the risk factors identified by Crawford a nd associates might not apply to other institutions. Therefore, the au thors conducted a retrospective review of their experience to analyze the surgical results obtained when repairing TAAs at an institution th at performs a large breadth of general vascular surgery but does not s pecifically specialize in the repair of TAAs. In addition, the authors determined whether any of 207 clinical variables was statistically as sociated with in-hospital mortality, ischemic spinal cord injury, or r enal failure and quantitated the strength of any such association by s tatistical analysis. Methods: A retrospective study was conducted of a ll patients who had an elective or emergency repair of a TAA at The Oh io State University Hospitals from January 1979 to March 1994. All pat ients in this series were operated on at Grant Hospital or the Univers ity Hospital in The Ohio State University Hospitals system. Student's t test was used to determine whether any of the 207 clinical variables analyzed in this study was significantly associated with any of the f ollowing three endpoints: in-hospital mortality,ischemic spinal cord i njury, or renal failure. Univariate and multivariate logistic regressi on analyses were applied to those variables that were significantly as sociated with the three endpoints in order to quantitate the strength of their association. Results: 110 patients underwent 112 repairs of a TAA. For the entire group, the overall in-hospital mortality rate fro m all causes was 26.7%. The most common underlying specific cause of d eath was coagulopathy. Ischemic spinal cord injury occurred in 19.6% a nd acute renal failure occurred in 14.4%. Univariate logistic regressi on analyses identified increasing aortic clamp time and intraoperative blood loss as variables that increased the risk of all three endpoint s. For in-hospital mortality, multivariate logistic analyses of preope rative and intraoperative variables demonstrated an increasing risk wi th advancing age, a greater number of units of red blood cells transfu sed intraoperatively, incidental operative procedures, and coagulopath y as significant variables. When postoperative variables were included in the analysis, postoperative coagulopathy, vascular complications, and hemodynamic instability were significantly associated with an incr eased risk of in-hospital mortality. Similarly, multivariate analyses demonstrated that increasing intraoperative blood loss and replacement of the distal half of the descending thoracic aorta were significantl y associated with ischemic spinal cord injury. Finally, multivariate a nalyses demonstrated that revision of any anastomosis significantly in creased the risk of developing postoperative renal failure. Conclusion s: Aortic clamp time affects in-hospital mortality, paraplegia, and di alysis. This is probably a result of the systemic effects of ischemia and reperfusion injury on the cardiac system, the coagulation/fibrinol ytic system, the spinal cord, and the kidneys. Furthermore, these data indicate that the patients who develop a coagulopathy are at very hig h risk of dying. Additional investigations designed to identify clinic al methods to prevent and control coagulopathies may help decrease the mortality associated with repair of the thoracoabdominal aorta. Final ly, the distal half of the descending thoracic aorta is the most criti cal segment of the aorta with respect to ischemic spinal cord injury..