[Abdominal complications following heart surgery]

Intra-abdominal complications occurring after cardiopulmonary bypass operations are rare but often fatal. There are only speculative approaches concerning the pathogenesis and the risk factors of these complications. The aim of our study was therefore to determine the causative factors and to evaluate the diagnostic and therapeutic measures, because early diagnosis and immediate treatment is essential for the outcome of the patients.

500 consecutive patients who underwent cardiopulmonary bypass procedures over a period of 14 months were examined for intra-abdominal complications. The records of these patients were reviewed in relation to possible risk factors and the group with intra-abdominal complications was compared with a random sample of 50 patients in respect of possible risk factors. The diagnostic procedures (serum lactate concentrations, sigmoidoscopy, coloscopy) and the therapeutic interventions were also evaluated.

9 (1.8%) of the 500 patients developed intra-abdominal complications. The mortality rate was 44% (4 of 9). 5 patients had bowel necrosis or ischaemic colitis. Pseudo-obstruction appeared in 5 cases. One patient developed cholecystitis and one acute haemorrhagic pancreatitis. Gastroduodenal complications were not observed. There was no difference between the group with intra-abdominal complications and the random sample with regard to sex, type of operation and preoperative intra-abdominal diseases. Clinical risk factors identified were: age, occlusive vascular disease, atrial fibrillation, prolonged aortic cross-clamping times and mean bypass times, intraoperative and postoperative need for supply of epinephrine and norepinephrine, implantation of an intraaortic balloon counterpulsation pump, low cardiac output, postoperative multiple organ failure. 8 out of the 9 patients had severe intraoperative surgical complications or general complications in the postoperative course. All patients with bowel necrosis or ischaemic colitis had abnormal serum lactate concentrations. With the aid of sigmoidoscopy in one patient, only bowel necrosis or ischaemic colitis could be detected. In one patient with pseudoobstruction, an operation was probably obviated by decompression of the colon by coloscopy. 6 of the 500 patients after cardiopulmonary bypass required emergency laparotomy. Two patients with bowel necrosis were saved by early hemicolectomy.

In reviewing both our results and data cited in earlier studies, intra-abdominal complications can generally be attributed to the following: Intraoperative surgical complications with the consequence of prolonged aortic cross clamping and total bypass times can cause low cardiac output and mesenteric hypoperfusion. Predominantly as a result of the low cardiac output, the use of vasopressors increases splanchnic ischaemia, in particular in patients with pre-existing occlusive vascular disease of the mesenteric arteries. Mucosal ischaemia might be aggravated by a concurrent pseudo-obstruction. On the other hand, intraoperative complications and low cardiac output can cause further complications and finally multiple organ failure. Multiple organ failure and ischaemia of the gut can initiate the vicious circle which is responsible for the high mortality from these complications. Early detection by careful physical examination and the combination of the diagnostic procedures and prompt treatment should lead to a reduction of mortality.