Mild or subclinical intravascular haemolysis subsequent to transcatheter occlusion of the patent arterial duct.

One of the important complications of transcatheter occlusion of the patent duct by insertion of either the Rashkind double umbrella or coil devices is intravascular haemolysis, particularly the severe form which occurs in 0.5-0.6% of cases. The incidence of subclinical or mild intravascular haemolysis including morphologic changes in the red cells, however, is not known, especially in the group of patients with residual shunt. We studied laboratory and haematologic changes in 37 patients subsequent to transcatheter occlusion. Their ages ranged from 2 years 2 months to 11 years 8 months (6.2 + 2.7 years), and the duration of occlusion had ranged from 1 month to 2 years 11 months (1.24 + 0.89 years). In 30 cases we had used the Rashkind double umbrella device, and nine of these patients (30%) had a residual shunt. The other seven ducts were closed with detachable coils, and five of these cases (71%) had residual shunting. There was evidence of mild or subclinical intravascular haemolysis in almost half the cases, although no patient developed acute intravascular haemolysis. Fragmented red cells, blur cells and spherocytes from blood smears were found in up to one-third of the overall series, with no differences found according to persistence of shunting. Haemosiderin was found in the urine of the group with residual shunting and in 13-23% of those with complete occlusion. Serum hypohaptoglobin was found in 9-13% of the patients with a residual shunt, and in 9-23% of those with complete occlusion. Four of the patients had haptoglobin levels < 50 mg/dl. There were no patients with reticulocytes counts > 2% in the blood smears. We conclude that subclinical or mild intravascular haemolysis, along with morphologic changes in the red blood cells, are significant findings subsequent to occlusion of the patent arterial duct with either the Rashkind double umbrella or detachable coils.