Moderate altitude increases right ventricular pressure and oxygen desaturation in adolescents with surgically closed septal defect.

Objectives. Abnormal right ventricular systolic pressure response (RVPR) during exercise has previously been demonstrated in patients with septal defects of the heart. Our study investigated whether moderate altitude affects RVPR and oxygen saturation during rest and exercise in patients with surgically closed septal defects. Design. Ten patients with surgically closed heart septal defects (six secundum atrial septal defects, four ventricular septal defects) were examined by cardiopulmonary exercise testing and by echocardiography at rest and during supine cycling at sea level. After 2 hours in a hypobaric chamber at 2500 m/8200 ft altitude, exercise echocardiography was repeated. Results. During sea level exercise four patients showed abnormal RVPR (>50 mm Hg). Acute hypoxic exposure led to right ventricular systolic pressure increase above 40 mm Hg in two patients. During altitude exercise seven patients showed abnormal RVPR. Average maximal right ventricular systolic pressure was 56.5 +/- 12.7 mm Hg and average for the lowest oxygen saturation was 80.0 +/- 5.7%. Two patients had simultaneous oxygen desaturation below 80% and right ventricular systolic pressure above 50 mm Hg. Conclusions. Moderate altitude affects right ventricular systolic pressure and oxygen saturation in adolescents with surgically closed ventricular or atrial septal defects. Moderate altitude may induce or aggravate abnormal RVPR and oxygen desaturation during exercise in these patients.