Effect of Alterations in Systemic Pressure upon Oxygen Saturation in Patients with Congenital Heart Disease

The effect of alteration of systemic pressure upon peripheral arterial oxygen saturation was studied in patients with congenital heart disease. Vasodepression produced by amyl nitrite caused a fall in systemic oxygen saturation in five patients with tetralogy of Fallot, two with patent ductus arteriosus and severe pulmonary hypertension, and one with Eisenmenger's complex. These changes did not occur in normals or in those with isolated puhmonic stenosis, trilogy of Fallot, or uncomplicated interatrial septal defect or patent duetus. Levarterenol on the other hand produced a rise in systemic oxygen content in one patient with tetralogy of Fallot. The use of these technics is suggested as a diagnostic aid and for the study of venoarterial shunts.