MATURATIONAL AND HEMODYNAMIC FACTORS PREDICTIVE OF INCREASED CYANOSISAFTER BIDIRECTIONAL CAVOPULMONARY ANASTOMOSIS

Bidirectional cavopulmonary anastomosis (BCA) is thought to be benefic ial in the palliation of patients with univentricular congenital heart disease considered at high risk for Fontan repair. Experience with pa tients undergoing BCA suggested that those who were older or larger at the time of surgery tended to be more cyanotic postoperatively than t heir younger and smaller counterparts. This study was designed to iden tify correlates of systemic arterial oxygen saturation after BCA. Spec ifically, it was postulated that maturational changes in blood now dis tribution might be associated with decreasing arterial oxygen saturati on. Database records of all 110 patients undergoing BCA at our institu tion from June 1988 until the end of 1991 were reviewed. Postoperative catheterization data were available for 66 patients. Twenty-one patie nts were excluded because they had potentially reversible causes of cy anosis yielding inestimable degrees of error in hemodynamic calculatio ns. In the remaining 45 patients, univariate and multivariate regressi on analyses were used to identify correlates of systemic arterial oxyg en saturation. Growth and maturation as represented by body surface ar ea exhibited a highly significant inverse correlation with arterial ox ygen saturation (p = 0.005), as did pulmonary vascular resistance (p = 0.003). Patients who underwent BCR when >3.9 years of age or with bod y surface area >0.65 m(2) were at significantly increased risk for exc essive postoperative cyanosis, defined as systemic arterial oxygen sat uration less than or equal to 75% (p <0.005). The interval between sur gery and catheterization correlated directly with arterial oxygen satu ration (p = 0.001), indicating a tendency toward earlier study of more cyanotic patients. None of the other variables examined correlated si gnificantly with arterial oxygen saturation. Patient age and body surf ace area were associated with postoperative desaturation independently of other known causes of cyanosis. Our findings suggest that BCA is o ptimally performed as interim palliation in young patients who may be expected to become suitable candidates for Fontan repair.