Mechanical blood trauma in circulatory-assist devices [E-Book]

Print version record.

1. Introduction.

2. Hemolysis.

3. Testing blood trauma in circulatory assist devices -- 3.1 Historical overview -- 3.2 Mechanical stresses which produce high levels of hemolysis.

4. Sublethal blood trauma -- 4.1 Effect of mechanical stress on RBC deformability -- 4.2 Effect of mechanical stress on RBC aggregation -- 4.3 Mechanical fragility of red blood cells.

5. Damage to leukocytes -- 5.1 Thrombosis and bleeding -- 5.1.1 In vitro studies of the mechanical stress effects on platelets.

6. In vitro testing devices for blood biocompatibility -- 6.1 Methods of plasma free Hb measurement -- 6.1.1 OxyHb absorbency at 540 nm -- 6.1.2 Cripps method -- 6.2 Normalized Index of Hemolysis.

7. Clinical issues and experience -- 7.1 Sequelae from hemolysis -- 7.2 Hemoglobin-haptoglobin complex -- 7.3 Effect of free Hb on platelets -- 7.4 Historical review of devices and resultant hemolysis issues -- 7.5 Surgical approaches to limit hemolysis.

8. Medical therapy elevated plasma free hemoglobin.

9. Concluding remarks.

10. References.

Mechanical cardiovascular assist devices must be properly designed to avoid damage to the blood they contact. The factors that affect the hemocompatibility of a cardiovascular assist device include three major non-physiological components - the material, fluid flow paths, and flow related stresses - as well as the device interaction with the native vasculature. Furthermore, the interaction of the device with the blood is not static. Foreign surfaces activate blood components including platelets, leukocytes and the coagulation cascade. Thrombus formation on the surface of the device can alter the fluid dynamics in a manner that causes erythrocyte damage ranging from significant hemolysis to sub-lethal trauma that can take many days to weeks to develop into a significant clinical problem. This sub-lethal blood trauma is not easily detectable without special equipment, which is typically unavailable in routine clinical practice. Surveillance for blood damage is often suboptimal in the clinical setting, but once clinically relevant hemolysis occurs, crucial decisions - device removal, replacement, or additional medical therapies including surgery or plasmapheresis - that take into account the risk/benefit of intervention must be quickly evaluated. The various pre-clinical designs and testing, surgical considerations, available surveillance techniques, and clinical consequences will be discussed using recent and historical case reports to highlight key points.

WorldCat record variable field(s) change: 650