Venesection in cyanotic heart disease

Venesection in cyanotic heart disease – calculation of volume to be removed

Venesection in cyanotic heart disease: Venesection in cyanotic heart disease is done only in symptomatic polycythemia with hemoglobin > 20 gm% and hematocrit > 65 %. Blood removed has to be replaced with equal amount of saline to avoid hypovolemia and to reduce the hematocrit.

Volume of blood to be removed by venesection in ml:
[(Observed PCV – Desired PCV ) / Observed PCV] x 70 x body weight in Kg.

Desired PCV (packed cell volume or hematocrit) is calculated based on the oxygen saturation. Average desired PCV is below 65% for a person with cyanotic congenital heart disease (CCHD). This is unlike polycythemia vera in which the recommended value is below 45% [1].

Rose SS and colleagues report a patient with CCHD who presented with symptomatic erythrocytosis with numbness and tingling sensation. Her hemoglobin was 25.2 g/dL and hematocrit 75.8%. It is not mandatory that every patient with erythrocytosis has to undergo venesection. They treated their patient with intravenous hydration and her symptoms resolved. Authors caution that factors which can precipitate hyperviscosity symptoms like dehydration and iron deficiency should be looked into and treated first. Such patients need only volume replacement and low dose iron therapy. Repeated phlebotomy as the risk of inducing iron deficiency and microcytosis. Microcytes increase the blood viscosity and can accentuate the risk of cerebrovascular accident [1].

Reference

1. Rose SS, Shah AA, Hoover DR, Saidi P. Cyanotic congenital heart disease (CCHD) with symptomatic erythrocytosis. J Gen Intern Med. 2007 Dec;22(12):1775-7.