The purpose of this study was to evaluate the intra-aortic balloon pump as a method of mechanical support for the management of patients with low output syndrome, following cardiac surgery with cardiopulmonary bypass. The results with early (intra-operative) and late (post-operative) support were compared, as well as the relationship among cardiopulmonary bypass time, aortic clamp time and mortality. Pre-operative left ventricle ejection fraction, as a prognosis index, and complications rates were also analysed. One hundred and thirty patients from Texas Heart Institute, during the period of January to December 1987, were studied retrospectively; there were 103 men and 27 women, with a mean age of 61.5 ± 10.7 (14 to 84) years. The mean weight body and body surface area were 75.5 ± 16.6 (42 to 134) kilograms and 1.87 ± 0.24 (1.08 to 2.60) square meters respectively. The mean time of cardiopulmonary bypass was 98 (33 to 299) minutes and the mean time of aortic clamp was 49 (10 to 122) minutes. All the patients had low cardiac output, associated with refractary arrythmias in 4 and after cardiac arrest in the intensive care unit in 2 patients. The intra-aortic balloon pump was left for variable periods of time from 15 minutes to 256 hours. The all cohort was divided in six groups, according to the early (intra-operative) insertion of the balloon pump (Group I), the late (post-operative) insertion (Group II), patient's age equal or inferior to 65 years Group III and Group IV age superior to 65 years, Group V and VI according cardiopulmonary bypass time up to 120 or superior to 120 minutes, and both were divided according to aortic clamp time (subgroup 1, up to 60 minutes and subgroup 2, superior to 60 minutes). The outcome was successful in 81 (62.3%) and 49 (37.7%) died (36.2% from Group I and 44% from Group II). The survival rate was greater in Group III (68.6%) than in Group IV (51 %) with p<0.05 showing statistical relevance of mortality in the older group. There were no significant associations between ejection fraction, aortic clamp time versus mortality but cardiopulmonary bypass had high statistical significance with p<0.01 for times over 120 minutes. Complications were found in 6 patients (4.6%). These data suggest that intra-aortic balloon pump is an effective mechanical support for the management of patients with low cardiac output following cardiac surgery with cardiopulmonary bypass, showing a tendency of best results when earliest applied, there is an influence of age and time of cardiopulmonary bypass over the mortality rates, suggesting that in these patients should be used more aggressive and effective circulatory support device.
Assisted circulation; Intra-aortic balloon pump