Post-exercise response of ventricular ejection fraction after total repair of congenital heart disease with left to right shunt

ABSTRACT

A radioisotope first pass study was done on patients over a period of 1 to 15 years (average 4.6 years) after repair for ventricular septal defect or arterial septal defect with a left to right shunt. The age of the patients ranged from 6 to 32 years (average 14.2 year) at the time of the study. The total work of exercise and the right and left ventricular ejection fraction(EF) were evaluated at rest and after exercise. The results were compared with the preoperative hemodynamic findings and with the age of patient at the time of the operation. 1) When the total work of exercise was divided with the maximal exercise capacity of the normal individual corresponding to the patients' height and body surface area (the percentage of total work), it were very low with the average of 40% of normal. There was no sexual difference, but the percentage of total work of exercise had significant correlation with the patients' age at the time of operation (r = -0.52,p<0.01) and post-exercise left ventricular ejection fraction (LVEF)(r = -0.39,p<0.05). 2) LVEF at rest had some correlation with the preoperative mean pulmonary arterial pressure (r = -0.29, p = 0.05), but showed no relationship with Qp/Qs or Rp/Rs ratios. The right ventricular ejection fraction (RVEF) at rest had no relations with the preoperative hemodynamic findings with maximal workload. 3) The post-exercise RVEF showed linear correlation with the preoperative Rp/Rs ratio (r = -0.49,p<0.005), and mean pulmonary arterial pressure (r = -0.37,p<0.05). The post-exercise LVEF had no significant correlation with any preoperative hemodynamic factors. 4) When greater than 5% increase in ventricular EF after exercise is considered normal, the group with the normal right and left ventricular responses (n = 11) showed normal preoperative Rp/Rs ratio (7.6 +/- 4.1). In the group with normal left, but abnormal right ventricular response (n = 9) and the group with abnormal biventricular response (n = 11), both demonstrated incremental increase in Rp/Rs ratio (20.1 +/- 11.3, 26.3 +/- 19.8 respectively). Normal right, but abnormal left ventricular reaction (n = 2) was noted in patients with residual aortic valvular insufficiency and residual ventricular septal defect. In conclusion, post-operative ventricular response was much more sensitive and informative than that of ventricular function at rest and to detect subclinical cardiac dysfunction. Post-exercise RVEF was closely correlated with preoperative pulmonary vascular hemodynamics, while post-exercise LVEF seemed to be a majo determinant of working capacity after repair.