Echocardiographic and radionuclide pulmonary blood flow patterns after transcatheter closure of patent ductus arteriosus

Background Transcatheter occlusion of patent ductus arteriosus (PDA) has been associated with protrusion of the occluder device into the left pulmonary artery (LPA). This study was conducted to evaluate the significance of occluder protrusion and its implications for potential obstruction of the LPA and associated decrease of left lung perfusion. Methods and Results Fifty-two patients underwent successful transcatheter PDA occlusion over a period of 5 years. In this study, 49 were reexamined between March and June 1995. In addition to clinical and echocardiographic examination, lung scintigraphy was performed. Protrusion into the LPA was present in 5 of 49 patients (10%). In these patients, maximal flow velocity in the LPA was significantly (P<.01) increased. Decreased left lung perfusion, defined as <40% of total pulmonary blood flow, was found in 7 or 49 patients (14%). Although mean left pulmonary perfusion was significantly (P=.02) decreased in patients with protrusion, there was considerable overlap with patients without protrusion, and only a weak correlation was found (r=-.35, P=.01) between flow-velocity and left lung prefusion. Conclusions Our results demonstrate that protrusion of the device in the LPA in an infrequent finding. If present, it is associated with increased maximal flow velocity in the LPA and diminished left lung perfusion. However, echocardiography and lung scintigraphy are weakly correlated. Increased maximal blood flow velocities in the proximal LPA proved to be a poor indicator of impaired left lung perfusion. Also, decreased perfusion occurs in the absence of echocardiographic evidence of device protrusion.