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A Novel Toroidal-Flow Left Ventricular Assist Device Minimizes Blood Trauma: Implications of Improved Ventricular Assist Device Hemocompatibility.

Ann Thorac Surg. 2018 Dec 23;:

Authors: Bartoli CR, Hennessy-Strahs S, Gohean J, Villeda M, Larson E, Longoria R, Kurusz M, Acker M, Smalling R

Abstract
BACKGROUND: Continuous-flow left ventricular assist devices (LVADs) cause blood trauma – von Willebrand factor degradation, platelet activation, and subclinical hemolysis. Blood trauma contributes to bleeding, thrombosis, and stroke, which cause significant morbidity and mortality. The TORVAD is a first-of-its kind, toroidal-flow LVAD designed to minimize blood trauma. We tested the hypothesis that the TORVAD causes less blood trauma than the HeartMate II LVAD.
METHODS: Whole human blood was circulated for 6 hours in ex vivo circulatory loops with a HeartMate II (n=8, 10,000 RPM, 70±6 mmHg, 4.0±0.1 L/min) or TORVAD (n=6, 144 RPM, 72±0.0 mmHg, 4.3±0.0 L/min). Von Willebrand factor degradation was quantified with electrophoresis and immunoblotting. Platelet activation was quantified by CD 41/61 ELISA. Hemolysis was quantified by plasma free hemoglobin ELISA.
RESULTS: The TORVAD caused significantly less degradation of high-molecular-weight von Willebrand factor multimers (-10±1 vs. -21±1%, p<0.0001), accumulation of low-molecular-weight von Willebrand factor multimers (22±2 vs. 45±2%, p<0.0001), and accumulation of von Willebrand factor degradation fragments (7±1 vs. 25±6%, p<0.05) than the HeartMate II. The TORVAD did not activate platelets whereas the HeartMate II caused significant platelet activation (645±20 vs. 1,581±150 ng/ml, p<0.001; normal human CD 41/61=593 ng/ml, range 400-800 ng/ml). Similarly, the TORVAD caused minimal hemolysis whereas the HeartMate II caused significant hemolysis (11±2 vs. 109±10 mg/dl, p<0.0001; normal human plasma free hemoglobin<4mg/dl).
CONCLUSIONS: The TORVAD design, with markedly lower shear stress and pulsatile flow, caused significantly less blood trauma that the HeartMate II. LVADs with reduced blood trauma are likely to improve clinical outcomes and expand LVAD therapy into patients with less advanced heart failure.

PMID: 30586577 [PubMed – as supplied by publisher]

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