LEFT-VENTRICULAR VENT AND NEUROPSYCHIATRIC MORBIDITY FOLLOWING CORONARY-ARTERY BYPASS

The marked decrease in neuropsychiatric morbidity (NPM) following coro nary artery bypass (CAB) over a period of four years led us to carry o ut a retrospective study in order to identify the cause. Two hundred f ifty-eight consecutive CAB procedures were performed between 1983 and 1986. For 133 patients (group A), the CAB procedure was performed with left ventricular vent (LVV) and for 125 patients (group B) without LV V. In group A, 93 patients (group A1) had cardiopulmonary bypass (CPB) with a bubble oxygenator and 40 patients (group A2) had CPB with a me mbrane oxygenator. In group B, 30 patients (group B1) had CPB with a m embrane oxygenator without filter in the arterial line and 95 patients (group B2) had CPB with a membrane oxygenator and filter in the arter ial line. The reduction in NPM arose from the removal of the LVV, as t he incidence of NMP was in group A 24.6 % versus 12.3 % in group B (p < 0.05). The substitution of the bubble oxygenator by a membrane oxyge nator does not alter the incidence of NPM : 23.3 % in group A1 versus 27.5 % in group A2 (p > 0.05) nor did incorporation of a filter in the arterial line : 10 % in group B1 versus 13.1 % in group B2 (p > 0.05) . Introduction of air in the left ventricle via an LVV catheter openin g and coronary arteriotomy therefore causes gazeous microembolic event s responsible for NPM following CAB.