Title
Hemolysis Following PDA Stent: A Novel Case Report
Introduction
Patent ductus arteriosus (PDA) stenting has become an increasingly common procedure in certain congenital heart diseases. Hemolysis has rarely been seen in transcatheter PDA closures with residual shunt. However, there have been no reports of hemolysis following PDA stenting; here, we present two such cases.
Clinical Case
Our first case was a patient with pulmonary atresia and ventricular septal defect who underwent ductal stenting on day of life 9 with 4x16mm Promus Elite Drug Eluting Stent (DES). After stenting, the proximal ostia of the left pulmonary artery (LPA) was fed via a side cell of the stent; therefore, angioplasty of the side cells was performed. The stent was not protruding into the descending aorta. Five days later, hemoglobin dropped from 13.5g/dL to 9.0g/dL. Total and indirect bilirubin, plasma free hemoglobin, and lactate dehydrogenase (LDH) were all elevated. Peripheral smear showed schistocytes. Direct Coombs was negative, and there was no ABO incompatibility. Hemolytic anemia secondary to mechanical shearing was the presumed diagnosis. The patient required four transfusions over two weeks. Ultimately, the hemolytic process self-resolved. Our second case was a patient with pulmonary atresia, intact ventricular septum, and tricuspid atresia who underwent ductal stenting with a 4x20mm Promus Elite DES on day of life 10. In contrast to the first case, hemolysis did not develop within the first few days following the procedure. At three months of age, angioplasty of PDA stent was performed. At five months of age, he underwent angioplasty and re-stenting of the PDA with another 4x20mm Promus Elite DES. This stent was also well positioned, with no protrusion into the descending aorta. Four days later, he developed scleral icterus. Hemoglobin at time of admission was 11.6g/dL, down from 16.6g/dL seven days prior. Total and indirect bilirubin and LDH were elevated. Direct Coombs test was negative. Peripheral smear showed schistocytes and burr cells with many reticulocytes. Once again, the cause was presumed to be hemolytic anemia due to mechanical shearing. The patient required one transfusion and ultimately underwent semi-urgent Glenn and PDA stent removal 20 days after the last cath.
Discussion
Hemolytic anemia following PDA stenting has not been previously reported. It has been rarely seen following PDA device closure with residual shunting, with rates ranging from 1-2%. The proposed mechanism is high velocity blood flow shearing as it comes into contact with the device. A PDA stent protruding into the aorta could cause this; however, this was not the case in either of our patients. Though the side cells of the stent covered the branch PA ostia in both our patients, it seems unlikely that this could serve as the nidus for shearing, particularly given that one patient underwent side cell dilation while another did not, yet both developed hemolysis. Therefore, the mechanism for this remains unclear. Given the increasing frequency of PDA stenting as an initial palliation for certain congenital heart defects, close attention should be paid to this possible phenomenon.