A Review and Assessment of Investigative Methods for Mechanically Induced Blood Trauma: Special Aspects in Rotary Blood Pumps

Abstract

In the last decade, enormous progress in the development and clinical use of cardiac assist devices has been made. Membrane pumps are already used routinely in clinical practice for implantation times of over a year, and some rotary pumps have attained reasonable quality for medium-term application. However, blood compatibility and thrombogenicity are still crucial problems, and thrombotic events in patients are still being reported. In rotary pumps with fast-spinning rotors and high-velocity gradients, thrombi can obtain characteristics different to those observed with membrane pumps. With unsatisfactory design or improper working conditions, small thrombi frequently may be released to the blood stream. This paper discusses the currently available models to assess mechanical blood trauma, and suggests design strategies to avoid thrombus formation. Finally, it considers in vitro and in vivo approaches to the evaluation of the performance and the safety of these pumps.