Preclosure pressure gradients predict patent ductus arteriosus patients at risk for later left pulmonary artery stenosis

The objective of this study was to evaluate the incidence of pre-existing catheterization left pulmonary artery (LPA) gradients and correlation of these gradients with later LPA stenosis after successful patent ductus arteriosus (PDA) occlusion. We performed a single-center review of 130 patients with PDA closure from October 1993 to February 2005. We analyzed the pre-PDA closure LPA pressure gradients at catheterization to determine if these were predictive of late LPA stenosis. On follow-up, a V_max >2 m/s by echocardiogram (transthoracic echocardiography; TTE) was considered indicative of possible LPA stenosis. Left lung perfusion of <35% was considered diagnostic of significant LPA stenosis. Post PDA closure, possible LPA stenosis by TTE was seen in 8 of 128 patients (6.25%). Seven of these eight had precatheter LPA gradients >7 mm Hg. Five of these had perfusion scans, three of the five had significant LPA stenosis, and two underwent LPA angioplasty. Patients with LPA catheter gradients ≥7 mm Hg were more likely to have possible LPA stenosis by TTE, significant LPA stenosis by lung scan, and intervention with LPA angioplasty. In conclusion, a preclosure main pulmonary artery-to-LPA pressure gradient ≥7 mm Hg was found in all patients who developed significant LPA stenosis on follow-up after transcatheter PDA closure. It appears likely that these patients have LPA abnormality rather than stenosis caused by the PDA occlusion device. Patients with preclosure LPA gradients ≥7 mm Hg should undergo follow-up evaluations for detection of significant stenosis and may require treatment if an important flow abnormality is documented.