The size of the pulmonary arteries and the results of the Fontan operation.

All patients (n = 334) undergoing the Fontan operation at the University of Bordeaux, France, and the University of Alabama Medical Center, Birmingham, were entered into a single data base to examine the relation, if any, between size of the pulmonary arteries and outcome. Recent follow-up was made of all patients. The time-related freedom from death or takedown of the Fontan operation was 78% at 1 month, 73% at 6 months, and 72%, 68%, 61%, and 50% at 1, 5, 10, and 15 years after the operation. The hazard function (instantaneous risk of the combined event at each moment in time after the operation) had a rapidly declining early phase that gave way at about 6 months to a late phase of hazard, which began slowly to rise about 8 years after the operation. One of the most powerful risk factors for death or takedown of the Fontan operation was the dimensions of the right and left pulmonary arteries, expressed as a McGoon ratio. By multivariate analysis, the risk of the combined event increased sharply when the McGoon ratio was less than about 1.8, and when the ratio was as low as 1.2 the probability of death or takedown within 30 days of the operation was predicted to be 55% when the right atrium was connected to the pulmonary artery and 34% when connected to the right ventricle. Other risk factors identified were age at operation, the presence of mitral atresia, the degree of main chamber hypertrophy, elevated pulmonary artery pressure, non-use of cardioplegia, global myocardial ischemic time, and attachment of the right atrium to the pulmonary artery rather than to the right ventricle.