Simple chronic transfusion therapy, a crucial therapeutic option for sickle cell disease, improves but does not normalize blood rheology: What should be our goals for transfusion therapy?

Abstract

Sickle cell anemia is characterized by a mutation resulting in the formation of an abnormal beta-hemoglobin called hemoglobin S. Hemoglobin S polymerizes upon deoxygenation, causing impaired red blood cell deformability and increased blood viscosity at equivalent hematocrits. Thus, sickle cell disease is a hemorheologic disease that results in various pathologic processes involving multiple organ systems including the lungs, heart, kidneys and brain. Red blood cell mechanics and the perturbations on blood flow-endothelial interaction underlie much of the pathology found in sickle cell disease. Transfusion therapy is one of the few therapeutic options available to patients, acting as both primary and secondary prevention of stroke. Transfusion therapy, both simple and exchange, is also used for unremitting and frequent pain crises and pulmonary hypertension. Therefore, understanding basic rheologic changes following transfusion inform other therapeutic options that aim to mitigate this diffuse pathologic process. This review will aim to highlight transfusion effects on blood rheology.

Vascular Instability and Neurological Morbidity in Sickle Cell Disease: An Integrative Framework

“…However, these findings are inconsistent with the observation that “at risk” regions of elevated OEF in watershed white matter zones appear to become smaller, rather than larger, following exchange transfusion (191). A possible explanation for this apparent juxtaposition is a difference in flow mechanics following simple and exchange transfusion, with exchange transfusion significantly reducing HbS% without substantially increasing hematocrit and viscosity (291). It is also possible that post-transfusion increases in CaO 2 and CVR somewhat restore the ability of the brain to compensate for slight increases in viscosity.…”

Personalizing transfusion in sickle cell disease: where is the canary in the mine?

“…Prior to hemolysis, though, HbS RBCs have increased aggregation and decreased deformability compared to HbA RBCs, increasing the viscosity of the blood and decreasing flow through the microcirculation. The goal of chronic transfusion therapy is to increase the number of RBCs with HbA and decrease the quantity of RBCs with HbS, which not only increases the oxygen carrying capacity of the blood through correction of the patient's anemia, but also improves flow through the microcirculation by decreasing aggregation and increasing the percentage of HbA RBCs with normal deformability …”

The Assessment of the Severity of Hemorheological Disorders in Patients With Arterial Hypertension

“…Доказано участие многих факторов в ме-ханизме увеличения артериального давления (АД) и развития АГ [1][2][3], в том числе уве-личение общего периферического сопротив-ления, вызванное как гипертонусом микро-сосудов, так и вязкостным сопротивлением потока крови [2,4]. Известны нарушения ге-мореологии у больных с длительным стажем АГ, которые проявлялись в увеличении вяз-кости крови, нарастании агрегации клеток красной крови и снижении их способности к деформации [2,4].…”

“…Известны нарушения ге-мореологии у больных с длительным стажем АГ, которые проявлялись в увеличении вяз-кости крови, нарастании агрегации клеток красной крови и снижении их способности к деформации [2,4]. К настоящему времени достоверно не установлено, какой из гемо-реологических факторов -вязкость плазмы, содержание эритроцитов, их агрегация, де-формируемость -следует считать основным в изменении параметров вязкости крови.…”

“…К настоящему времени достоверно не установлено, какой из гемо-реологических факторов -вязкость плазмы, содержание эритроцитов, их агрегация, де-формируемость -следует считать основным в изменении параметров вязкости крови. Проведенные исследования демонстрирова-ли влияние современных антигипертензив-ных средств на реологические характери-стики крови больных АГ: положительный эффект антагонистов кальция [4], бета-адре-ноблокаторов [5,6], ингибиторов ангиотен-зинпревращающего фермента [7].…”