Report From the Second Joint Study on the Natural History of Congenital Heart Defects (nhs-2)

The purpose of this study was to determine exercise tolerance and cardiac response to exercise for a large cohort of adult subjects with aortic stenosis, pulmonary stenosis, or ventricular septal defect participating in the Second Natural History Study of Congenital Heart Defects (NHS-2). Methods and Results.Exercise testing was performed on 134 of 235 NHS-2 full participants with aortic stenosis, 195 of 331 NHS-2 full participants with pulmonary stenosis, and 324 of 594 NHS-2 full participants with ventricular septal defect. A Bruce treadmill exercise protocol was used. Mean exercise duration for patients with aortic stenosis, pulmonary stenosis, and ventricular septal defect was 86.5%, 94.2%, and 90.8% of predicted, respectively. For patients with aortic stenosis, there was a direct relation between echocardiographic Doppler maximum transaortic gradient and ST segment change during exercise. ST segment change during exercise was very uncommon for patients with pulmonary stenosis. For patients with ventricular septal defect, there was an association between arrhythmias noted during exercise and the presence of associated aortic insufficiency. Although exercise duration was well preserved for patients with each of the three defects, exercise tolerance was subnormal. (Circulation 1993;87(suppl I):I-102-I-113).