Changing hemodynamics in patients with transposition of the great arteries.

Follow-up cardiac catheterizations were carried out on 65 patients with transposition of the great arteries. Patent ductus arteriosus (PDA) was a significant problem in this group only when closure resulted in a precipitous drop in arterial oxygen saturation. Spontaneous closure of ventricular septal defects (VSD) occurred in approximately 20% of patients while natural or surgically created atrial septal defects (ASD) tended to persist. Pulmonary stenosis (PS) was found in 28% of patients with an intact ventricular septum and 50% of those with VSD. Pulmonary artery hypertension (PAH) or pulmonary vascular obstruction (PVO) or both, were present in about half of the patients with an intact ventricular septum and all the infants with a large VSD without pulmonary artery banding or pulmonic stenosis (PS). PS, usually but not invariably, tended to protect the pulmonary vasculature.