Abstract 3219: Not Ventricular Dysfunction But Abnormal Quantity of Hemoglobin and Respiratory Muscles Weakness Determine the Exercise Capacity in Adolescence and Young Adult After Fontan Procedure
It remains unknown what kinds of factors determine the lower exercise capacity in adolescence and young adult after Fontan procedure. The respiratory muscles function has been demonstrated the important factor to relate to the exercise capacity in adult patients with acquired heart disease. To determine whether the strength of respiratory muscles or cardiac functional factors affect the exercise capacity, we studied 127 consecutive patients between 6 and 32 years old retrospectively. They underwent Fontan procedure between 1 and 24 years old. Cardiopulmonary exercise test, cardiac catheterization and pulmonary function test were done in the similar period between 1998 and 2005. We performed these examinations every five years after Fontan procedure or at the time of suspicious abnormal hemodynamics. The strength of respiratory muscles was assessed by the peak expiratory flow rate (PEFR). The patients with peak oxygen consumption (pkVO2) less than 20ml/kg/min were defined as lower exercise capacity (n=48) and the patients with pkVO2 20ml/kg/min or more as non-lower exercise capacity (n=79). The multiple logistic regression analysis revealed that five factors had independent relationships with lower exercise capacity. The lower exercise capacity was associated with an odds ratio of 17.4(95%CI, 3.6 – 83.5: p<0.001) for elder age(≥15 years), 14.5 (95%CI, 1.3–153: p=0.026) for two ventricular type, 8.1(95C.I. 1.2–53.8: p=0.029) for anemia(Hb <13.0g/dl ) or polycythemia(Hb≥18.0g/dl), 5.0(95C.I. 1.3–18.7: p=0.015) for female and 4.1(95C.I. 1.1–14.2: p=0.028) for respiratory muscles weakness (PEFR<76%). PkVO2 was less than 20ml/kg/min in two thirds of the elder age. Within these adolescence and young adult, non-lower exercise capacity was independently related to only PEFR and hemoglobin in the multiple analysis. If PEFR was 80% or more, the odds ratio for non-lower exercise capacity was 7.2(95C.I. 1.5–33.1: p=0.011). Similarly if hemoglobin was from 13.0g/dl to 18.0g/dl, the odds ratio for non-lower exercise capacity was 8.1(95C.I. 1.3– 49.0: p=0.020). In conclusion we suggest that to maintain the strength of respiratory muscles and the appropriate hemoglobin may prevent exercise capacity from declining in the youth after Fontan procedure.