Effects of Hemodilution on Outcome After Modified Blalock-Taussig Shunt Operation in Children With Cyanotic Congenital Heart Disease

Objective: Cyanotic congenital heart diseases (CCHD) with secondary polycythemia and hyperviscosity state are associated with a reduction in blood flow, stagnation of blood, and thrombosis. Sufficient hemodilution in cyanotic children results in higher blood flow and significant reductions in perioperative blood loss. The aim of this study was to investigate similar beneficial effects of hemodilution in preventing shunt thrombosis and decreasing postoperative blood loss after modified Blalock-Taussig (BT) shunt operations in children with CCHD.

Design: Prospective, randomized, controlled study.

Setting: Cardiac center of a tertiary care, referral hospital.

Participants: Fifty children with CCHD undergoing modified BT shunt operations.

Interventions: Patients were randomized into 2 groups. The study group (n = 25) received a calculated amount of 6% hydroxyethyl starch (200/0.5) solution to bring down the hematocrit to 45%, whereas the control group (n = 25) received 5% dextrose solution intraoperatively as per the authors’ normal protocol.

Measurements and Main Results: Effects of hemodilution on shunt patency, postoperative blood loss at 24 hours, blood and blood component usage, and re-exploration rates were recorded. The shunt patency rate was significantly higher in the study group than the control group (100% and 84%, respectively, p < 0.05). Postoperative blood loss at 24 hours was significantly higher in the control group than in the study group (14.4 ± 11.8 mL/kg and 9.9 ± 8 mL/kg, respectively, p < 0.05). The number of recipients and the amount of blood and blood components administered were higher in the control group, but they were not statistically significant. The re-exploration rate (for excessive postoperative chest-tube drainage) was significantly higher in the control group than the study group (12% and 0%, respectively, p < 0.05).

Conclusion: Hemodilution in CCHD patients undergoing modified BT shunt surgery has beneficial effects including improved shunt patency because of higher blood flow through the graft and less postoperative blood loss, which may be attributed to the lower viscosity produced by hemodilution.

Key words: congenital heart disease, systemic-pulmonary artery shunt, hemodilution, hydroxyethyl starch, postoperative blood loss