The Use of Fluid Mechanics to Predict Regions of Microscopic Thrombus Formation in Pulsatile VADs

Stephen R. Topper, Michael A. Navitsky, Richard B. Medvitz, Eric G. Paterson, Christopher Siedlecki, Margaret June Slattery, Steven Deutsch, Gerson Rosenberg, Keefe B. Manning

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

We compare the velocity and shear obtained from particle image velocimetry (PIV) and computational fluid dynamics (CFD) in a pulsatile ventricular assist device (VAD) to further test our thrombus predictive methodology using microscopy data from an explanted VAD. To mimic physiologic conditions in vitro, a mock circulatory loop was used with a blood analog that matched blood's viscoelastic behavior at 40% hematocrit. Under normal physiologic pressures and for a heart rate of 75 bpm, PIV data is acquired and wall shear maps are produced. The resolution of the PIV shear rate calculations are tested using the CFD and found to be in the same range. A bovine study, using a 50 cc Penn State V-2 VAD, for 30 days at a constant beat rate of 75 beats per minute (bpm) provides the microscopic data whereby after the 30 days, the device is explanted and the sac surface analyzed using scanning electron microscopy (SEM) and, after immunofluorescent labeling for platelets and fibrin, confocal microscopy. Areas are examined based on PIV measurements and CFD, with special attention to low shear regions where platelet and fibrin deposition are most likely to occur. Data collected within the outlet port in a direction normal to the front wall of the VAD shows that some regions experience wall shear rates less than 500 s-1, which increases the likelihood of platelet and fibrin deposition. Despite only one animal study, correlations between PIV, CFD, and in vivo data show promise. Deposition probability is quantified by the thrombus susceptibility potential, a calculation to correlate low shear and time of shear with deposition.

Original languageEnglish (US)
Pages (from-to)54-69
Number of pages16
JournalCardiovascular Engineering and Technology
Volume5
Issue number1
DOIs
StatePublished - Jan 1 2014

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Rheology
Fluid mechanics
Mechanics
Heart-Assist Devices
Velocity measurement
Hydrodynamics
Thrombosis
Computational fluid dynamics
Platelets
Fibrin
Blood Platelets
Shear deformation
Blood
Shear walls
Confocal microscopy
Hematocrit
Confocal Microscopy
Electron Scanning Microscopy
Labeling
Microscopy

All Science Journal Classification (ASJC) codes

  • Biomedical Engineering
  • Cardiology and Cardiovascular Medicine

Cite this

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title = "The Use of Fluid Mechanics to Predict Regions of Microscopic Thrombus Formation in Pulsatile VADs",
abstract = "We compare the velocity and shear obtained from particle image velocimetry (PIV) and computational fluid dynamics (CFD) in a pulsatile ventricular assist device (VAD) to further test our thrombus predictive methodology using microscopy data from an explanted VAD. To mimic physiologic conditions in vitro, a mock circulatory loop was used with a blood analog that matched blood's viscoelastic behavior at 40{\%} hematocrit. Under normal physiologic pressures and for a heart rate of 75 bpm, PIV data is acquired and wall shear maps are produced. The resolution of the PIV shear rate calculations are tested using the CFD and found to be in the same range. A bovine study, using a 50 cc Penn State V-2 VAD, for 30 days at a constant beat rate of 75 beats per minute (bpm) provides the microscopic data whereby after the 30 days, the device is explanted and the sac surface analyzed using scanning electron microscopy (SEM) and, after immunofluorescent labeling for platelets and fibrin, confocal microscopy. Areas are examined based on PIV measurements and CFD, with special attention to low shear regions where platelet and fibrin deposition are most likely to occur. Data collected within the outlet port in a direction normal to the front wall of the VAD shows that some regions experience wall shear rates less than 500 s-1, which increases the likelihood of platelet and fibrin deposition. Despite only one animal study, correlations between PIV, CFD, and in vivo data show promise. Deposition probability is quantified by the thrombus susceptibility potential, a calculation to correlate low shear and time of shear with deposition.",
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The Use of Fluid Mechanics to Predict Regions of Microscopic Thrombus Formation in Pulsatile VADs. / Topper, Stephen R.; Navitsky, Michael A.; Medvitz, Richard B.; Paterson, Eric G.; Siedlecki, Christopher; Slattery, Margaret June; Deutsch, Steven; Rosenberg, Gerson; Manning, Keefe B.

In: Cardiovascular Engineering and Technology, Vol. 5, No. 1, 01.01.2014, p. 54-69.

Research output: Contribution to journalArticle

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AU - Navitsky, Michael A.

AU - Medvitz, Richard B.

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AU - Siedlecki, Christopher

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