Decline in arterial partial pressure of oxygen after exercise: a surrogate marker of pulmonary vascular obstructive disease in patients with atrial septal defect and severe pulmonary hypertension.
OBJECTIVE
To examine the utility of decline in arterial partial pressure of oxygen after exercise as a marker of pulmonary vascular obstructive disease in patients with atrial septal defect and pulmonary hypertension.


METHODS
Treadmill exercise was performed in 18 patients with atrial septal defect and pulmonary hypertension. Arterial blood gas samples were obtained before and after peak exercise. A decline in the arterial pressure of oxygen of more than 10 millimetres of mercury after exercise was considered significant based on preliminary tests conducted on the controls. Cardiac catheterisation was performed in all patients and haemodynamic data sets were obtained on room air, oxygen, and a mixture of oxygen and nitric oxide (30-40 parts per million).


RESULTS
There were 10 patients who had more than a 10 millimetres of mercury drop in arterial partial pressure of oxygen after exercise and who had a basal pulmonary vascular resistance index of more than 7 Wood units per square metre. Out of eight patients who had less than a 10 millimetres of mercury drop in arterial partial pressure of oxygen after exercise, seven had a basal pulmonary vascular resistance index of less than 7 Wood units per square metre, p equals 0.0001. A decline in arterial partial pressure of oxygen of more than 10 millimetres of mercury predicted a basal pulmonary vascular resistance index of more than 7 Wood units per square metre with a specificity of 100% and a sensitivity of 90%.


CONCLUSIONS
A decline in arterial partial pressure of oxygen following exercise appears to predict a high pulmonary vascular resistance index in patients with atrial septal defect and pulmonary hypertension. This test is a useful non-invasive marker of pulmonary vascular obstructive disease in this subset.
Department of Pediatric Cardiology, Amrita Institute of Medical Sciences, Amrita Vishwa Vidyapeetham, Kochi, Kerala, India.
Srinivas
S
Laksmivenkateshiah
Anil K
AK
Singhi
Balu
B
Vaidyanathan
Edwin
E
Francis
Sundaram R
SR
Karimassery
Raman K
RK
Kumar
D000328:Adult; D001785:Blood Gas Monitoring, Transcutaneous / Q000379:methods*; D006328:Cardiac Catheterization; D015444:Exercise; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006344:Heart Septal Defects, Atrial / Q000150:complications / Q000628:therapy; D006801:Humans; D006976:Hypertension, Pulmonary / Q000150:complications / Q000628:therapy; D008297:Male; D010313:Partial Pressure; D011446:Prospective Studies; D011668:Pulmonary Veno-Occlusive Disease / Q000150:complications / Q000175:diagnosis*