CARDIOPULMONARY FUNCTION IN ADULT PATIENTS LATE AFTER FONTAN REPAIR

Objectives. The clinical status and exercise assessment of adult patie nts late after the Fontan operation were reviewed to determine cardiov ascular function. Background. The Fontan operation is the final operat ion for many patients with tricuspid atresia or a single ventricle. Fo llow-up reports describe most patients to be in Canadian Cardiovascula r Society functional class I or II. Objective measures of cardiac perf ormance in the pediatric age group have shown significant dysfunction. Methods. Forty-seven adult patients were seen late after the Fontan o peration at the Toronto Congenital Cardiac Centre for Adults. Thirty o f these underwent cycle ergometry to determine maximal exercise capaci ty. Maximal ventilation, maximal oxygen uptake and anaerobic threshold were determined from a ramp exercise protocol. Ejection fraction at r est and during exercise was measured with gated radionuclide angiograp hy. Results were compared with those of eight normal volunteers. Resul ts are given as mean +/- SD. Results. Thirty patients underwent cardio pulmonary exercise testing 6.7 +/- 3.9 years after a first Fontan oper ation. Clinically 93% were in functional class I or II. The Fontan gro up patients had a significantly lower maximal work load (548 +/- 171 v s. 1,094 +/- 190 kilopond-meters, p < 0.00001), anaerobic threshold (1 1.2 +/- 2.9 vs. 23.6 +/- 4.6 ml/kg per min) and maximal oxygen consump tion (14.8 +/- 4.5 vs. 42.1 +/- 10.0 ml/kg per min). Systemic ventricu lar ejection fraction was lower at rest (38 +/- 12% vs. 58 +/- 7%) and during exercise (40 +/- 15% vs. 70 +/- 8%). Conclusions. Despite a cl inical impression of good function, by objective measures adult patien ts continue to have significant cardiovascular limitation late after t he Fontan operation.