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. 2014 Mar-Apr;60(2):237-40.
doi: 10.1097/MAT.0000000000000034.

Thrombus formation patterns in the HeartMate II ventricular assist device: clinical observations can be predicted by numerical simulations

Wei-Che Chiu  1 , Marvin J Slepian, Danny Bluestein
Affiliations

Thrombus formation patterns in the HeartMate II ventricular assist device: clinical observations can be predicted by numerical simulations

Wei-Che Chiu et al. ASAIO J. 2014 Mar-Apr.

Abstract

Postimplant device thrombosis remains a life-threatening complication and limitation of continuous-flow ventricular assist devices (VADs). Using advanced computational fluid dynamic (CFD) simulations, we successfully depicted various flow patterns, recirculation zones, and stagnant platelet trajectories which promote thrombus formation and observed that they matched actual thrombus formation patterns observed in Thoratec HeartMate II VADs explanted from patients with pump thrombosis. Previously, these small eddies could not be captured by either digital particle image velocimetry or CFD due to insufficient resolution. Our study successfully demonstrated the potential capability of advanced CFD to be adopted for device optimization, leading to enhanced safety and efficacy of VADs for long-term destination therapy.

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Conflict of interest statement

Disclosure Statement:

This paper is not under consideration elsewhere.

None of the paper’s contents have been previously published.

All authors have read and approved the manuscript.

None of the authors has a conflict of interest to declare.

Figures

Figure 1
Figure 1. Numerical Prediction of Thrombus Formation Patterns in HMII
(A) Freeze frame depiction of the velocity vector field of the HMII simulation (4 L/min of cardiac output with the impeller speed of 10,000 rpm). Exterior (B) and interior (C) features of HMII: flow-straightener, impeller and diffuser (blue, yellow and pink, accordingly). (D & E) Stagnant platelet trajectories are observed along the posterior side of the flow-straightener and the entry of the impeller blades is characterized by stagnant flow patterns; (D: inset i, ii & iii) recirculation zones were observed at the downstream of the flow straightener blades spanning approximately 1-2 mm. (D: inset iv) Platelet trajectories indicate a stagnation zone at the rear hub, and (E) Entrapped circular flow patterns at the entry towards the impeller blades.
Figure 2
Figure 2. Clinical Observations of Thrombus Formation in HMII
(A & B) Previous DPIV results along the flow-straightener of HMII: (A) The geometry of HMII flow straightener. (B) The velocity flow field along the flow straightener obtained with DPIV. Thrombus formation was reported at the regions of the rear hub (i.e. the bearing between the flow-straightener and the impeller) and the entry of the impeller blades very similar to those observed in our study (C, D & F). The thrombus extended along the flow-straightener blades as has been reported clinically (E).
See this image and copyright information in PMC

References

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