Significant correlation of comprehensive Aristotle score with total cardiac output during the early postoperative period after the Norwood procedure.

Background: The comprehensive Aristotle score has been proposed as an individualized measure of the complexity of a given surgical procedure and has been reported to significantly correlate with postoperative morbidity and mortality after the Norwood procedure. An important factor leading to postoperative morbidity and mortality is low cardiac output. We studied the correlation between the comprehensive Aristotle score and cardiac output (CO) in infants after the Norwood procedure. Methods and Results: Respiratory mass spectrometry was used to continuously measure systemic oxygen consumption (VO2) in 22 infants for 72 hours postoperatively. Arterial, superior vena caval and pulmonary venous blood gases were measured at 2 to 4 hour intervals to calculate CO. The comprehensive Aristotle score was collected. Hospital mortality was 4.5%. The comprehensive Aristotle score ranged from 14.5 to 23.5 and negatively correlated with CO ( P = 0.027). Among the patient-adjusted factors, myocardial dysfunction (n = 10), mechanical ventilation to treat cardiorespiratory failure ( n = 9) and atrioventricular valve regurgitation ( n = 4) (P = 0.01) negatively correlated with CO (P = 0.06 to 0.07). Aortic atresia (n = 9) was associated with a lower CO ( P = 0.01) for the first 24 hours which linearly increased overtime ( P = 0.0001). No correlation was found between CO and other factors (P > 0.3 for all). Conclusions: Comprehensive Aristotle score significantly negatively correlates with CO after the Norwood procedure. A preoperative estimation of the comprehensive Aristotle score, particularly in association with myocardial dysfunction, mechanical ventilation to treat cardiorespiratory failure, atrioventricular valve regurgitation and aortic atresia may help to anticipate a high postoperative morbidity with low cardiac output syndrome.