Red blood cell survival in patients with ventricular septal defect and patent ductus arteriosus.

Hemolysis of red blood cells (RBC) in stenotic or regurgitant cardiac valvular lesions has been felt to be due to mechanical trauma and shearing stress caused by turbulence of blood. RBC are also under a shearing stress from turbulence in high-pressure shunts, such as ventricular septal defect (VSD) and patent ductus arteriosus (PDA). The RBC survival time was measured in five patients with VSD and in 11 patients with PDA to determine if there was hemolysis of RBC. Six children without cardiac disease were also studied to obtain the control values for RBC survival times in th laboratory. Two patients with PDA were restudied one year postoperatively. Additional parameters studied were hemoglobin, packed cell volume, reticulocyte cell count, peripheral smear, and urinary hemosiderin. The hemoglobin values and the packed cell volumes were comparable in the two groups. The reticulocyte cell count was normal in all. Urinary hemosiderin was negative in all and the peripheral smear did not reveal abnormal red cell morphology. Mean red cell survival half-life in the two groups was identical. The red cell survival was abnormally low in two patients of PDA. Since one of these two patients had persistently low RBC survival postoperatively, the authors believe that the low red cell survival in this patient was unrelated to the presence of PDA. Based on findings in the small number of cases, the authors conclude that left to right shunt through a VSD or PDA is probably not associated with significant red blood cell destruction.