The modified Fontan procedure: morphometry and surgical implications

Background. The modified Fontan procedure for patients with only one well-formed ventricle is now widely regarded as palliative, not curative. Methods. To improve the surgical management and postoperative follow-up of such patients, a morphometric study of 33 postmortem cases was done. Results. The three main causes of death were congestive heart failure (82%), arrhythmias (12%), and central nervous system dysfunction (6%). The cross-sectional area of the Fontan anastomosis (FA) relative to the systemic venous area (SVA) and relative to the body surface area (BSA) revealed that the Fontan pathway was often obstructive. The mean FA/SVA index was 73% less than normal: 0.54 ± 0.22, range 0.13 to 0.98. The mean FA/BSA index was 70% less than normal: 143.52 ± 50.01 mm2/M2, range 55.09 to 261.67 mm2/M2. Conclusions. The main surgical challenge is to minimize or eliminate prepulmonary stenosis. Although significant postoperative obstruction was often not evident hemodynamically because of small or absent gradients, the presence of important obstruction of the Fontan pathway was clearly revealed by morphometry.