Assessment of operability in d-transposition of great arteries with ventricular septal defect: A practical method

Introduction : Pulmonary vascular disease is a risk factor in the surgical management of patients with d-transposition of great arteries (d-TGA) and a ventricular septal defect (VSD). In older infants or children with this physiology, the question of operability often arises. Cardiac catheterization in this condition can be fallacious. It is well known that oxygen reduces pulmonary arterial pressure and pulmonary vascular resistance especially where irreversible pulmonary vascular obstructive disease has still not set in. We tried to implement this effect of oxygen in correlation with echocardiography in patients with TGA-VSD physiology where operability was in question. Methods : Patients with d-TGA and a large post tricuspid shunt in whom operability was considered doubtful were selected for the study. We administered humidified oxygen at the rate of 10 litres/minute by mask for 48 hours in the ward or intensive care unit. After administration of oxygen we reassessed the child echocardiographically looking for signs of lowering of pulmonary vascular resistance which included increased pulmonary venous blood flow to the left atrium (LA) and right to left shunting across the VSD. Observation : We studied 1 patient with d-TGA and aortopulmonary window (APW), 4 patients with TGA / large VSD and 1 patient with Taussig-Bing anomaly. The age of the studied children ranged from 4 months to 3 years with a mean age of 1.1 years. After administering oxygen as described, echocardiogram showed an increase in pulmonary venous blood flow to the LA and right to left shunting across the VSD in 5 patients and increased flow reversal in aorta in presence of the APW. Conclusion : Patients with TGA/VSD physiology with doubtful operability can be subjected to this method of determining operability using echocardiography after administering oxygen. Although not 100% accurate in predicting long term postoperative pulmonary hypertension, this is a simple, noninvasive method that can aid in decision making in such a situation.