Incorporation of Electronics within a Compact, Fully Implanted Left Ventricular Assist Device

Bourque, Kevin; Gernes, D.; Loree, H.; Richardson, J S; Poirier, Victor L.; Barletta, N.; Fleischli, A.; Foiera, G.; Gempp, Thomas; Schoeb, Reto

doi:10.1046/j.1525-1594.2002.07118.x

Cited by 7 publications

(6 citation statements)

References 7 publications

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“…The large gaps enable the sharp speed changes employed by the HM3 artificial pulse. 17,18 By alternating the speed every 2 seconds, changing blood flow within the LVAD precludes the organization of recirculation and stasis zones. The role pulsatility plays in von Willebrand factor degradation leads to a hypothesis that gastrointestinal bleeding, hemorrhagic stroke, and epistaxis may be reduced by reducing effects on blood proteins and reducing platelet activation, although clinical experience will be required to substantiate that.…”

Section: Discussionmentioning

confidence: 99%

Design Rationale and Preclinical Evaluation of the HeartMate 3 Left Ventricular Assist System for Hemocompatibility

Bourque

Cotter²,

Dague³

et al. 2016

ASAIO Journal

Self Cite

172

132

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The HeartMate 3 (HM3) left ventricular assist device (LVAD) is designed to support advanced heart failure patients. This centrifugal flow pump has a magnetically levitated rotor, artificial pulse, textured blood-contacting surfaces, optimized fluid dynamics, large blood-flow gaps, and low shear stress. Preclinical tests were conducted to assess hemocompatibility. A computational fluid dynamics (CFD) model guided design for low shear stress and sufficient washing. Hemolysis testing was conducted on six pumps. Plasma-free hemoglobin (PfHb) and modified index of hemolysis (MIH) were compared with HeartMate II (HMII). CFD showed secondary flow path residence times between 27 and 798 min, comparable with main flow residence times between 118 and 587 min; HM3 vs. HMII shear stress exposure above 150 Pa was 3.3 vs. 11 mm within the pump volume and 134 vs. 604 mm on surfaces. In in vitro hemolysis tests at 2, 5, and 10 L/min, average pfHb 6 hours after test initiation was 58, 74, and 157 mg/dl, compared with 112, 123, and 353 mg/dl for HMII. The HM3/HMII ratio of average MIH at 2, 5, and 10 L/min was 0.29, 0.36, and 0.22. Eight 60 day bovine implants were tested with average flow rates from 5.6 to 6.4 L/min with no device failures, thrombosis, or hemolysis. Results support advancing HM3 to clinical trials.

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Section: Discussionmentioning

confidence: 99%

Design Rationale and Preclinical Evaluation of the HeartMate 3 Left Ventricular Assist System for Hemocompatibility

Bourque

Cotter²,

Dague³

et al. 2016

ASAIO Journal

Self Cite

172

132

View full text Add to dashboard Cite

show abstract

“…The geometry and mesh of the LVAD were created using Gambit software (ANSYS, Inc., Canonsburg, PA, USA). The dimensions were derived from scaling previously published figures of the HeartMate III using as references the diameter and height of the device, 69 and 39 mm, respectively (2,20,21). The HeartMate III was chosen partly because its dimensions and clear figures were readily available.…”

Section: Methodsmentioning

confidence: 99%

“…Due to high shear rates in the device, blood was modeled as a Newtonian, incompressible fluid with a density (ρ) of 1050 kg/m 3 and viscosity (µ) of 0.0035 Pa/s. Isothermal conditions were assumed because the heat produced by the HeartMate III is quickly carried away by blood flow, resulting in a temperature increase of no greater than 1°C (21).…”

Section: Methodsmentioning

confidence: 99%

Computational Fluid Dynamics Analysis to Determine Shear Stresses and Rates in a Centrifugal Left Ventricular Assist Device

Selgrade

Truskey

2012

Artificial Organs

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Axial flow left ventricular assist devices (LVADs) are a significant improvement in mechanical circulatory support. However, patients with these devices experience degradation of large von Willebrand factor (vWF) multimers, which is associated with bleeding and may be caused by high shear stresses within the LVAD. In this study, we used computational fluid mechanics to determine the wall shear stresses, shear rates, and residence times in a centrifugal LVAD and assess the impact on these variables caused by changing impeller speed and changing from a shrouded to a semi-open impeller. In both LVAD types, shear rates were well over 10 000/s in several regions. This is high enough to degrade vWF, but it is unclear if residence times, which were below 5 ms in high-shear regions, are long enough to allow vWF cleavage. Additionally, wall shear stresses were below the threshold stress of 10 Pa only in the outlet tube so it is feasible to endothelialize this region to enhance its biocompatibility.

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“…Thoratec HeartMate III: radial self-bearing system (36)(37)(38)(39)(40) The HeartMate III, as shown in Fig. 5, is a totally implantable uni-/biventricular assist system (VAS).…”

Section: Future Maglev Systemsmentioning

confidence: 99%

Third‐generation Blood Pumps With Mechanical Noncontact Magnetic Bearings

2006

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This article reviews third-generation blood pumps, focusing on the magnetic-levitation (maglev) system. The maglev system can be categorized into three types: (i) external motor-driven system, (ii) direct-drive motor-driven system, and (iii) self-bearing or bearingless motor system. In the external motor-driven system, Terumo (Ann Arbor, MI, U.S.A.) DuraHeart is an example where the impeller is levitated in the axial or z-direction. The disadvantage of this system is the mechanical wear in the mechanical bearings of the external motor. In the second system, the impeller is made into the rotor of the motor, and the magnetic flux, through the external stator, rotates the impeller, while the impeller levitation is maintained through another electromagnetic system. The Berlin Heart (Berlin, Germany) INCOR is the best example of this principle where one-axis control combination with hydrodynamic force achieves high performance. In the third system, the stator core is shared by the levitation and drive coil to make it as if the bearing does not exist. Levitronix CentriMag (Zürich, Switzerland), which appeared recently, employs this concept to achieve stable and safe operation of the extracorporeal system that can last for a duration of 14 days. Experimental systems including HeartMate III (Thoratec, Woburn, MA, U.S.A.), HeartQuest (WorldHeart, Ottawa, ON, Canada), MagneVAD (Gold Medical Technologies, Valhalla, NY, U.S.A.), MiTiHeart (MiTi Heart, Albany, NY, U.S.A.), Ibaraki University's Heart (Hitachi, Japan) and Tokyo Medical and Dental University/Tokyo Institute of Technology's disposable and implantable maglev blood pumps are also reviewed. In reference to second-generation blood pumps, such as the Jarvik 2000 (Jarvik Heart, New York, NY, U.S.A.), which is showing remarkable achievement, a question is raised whether a complicated system such as the maglev system is really needed. We should pay careful attention to future clinical outcomes of the ongoing clinical trials of the second-generation devices before making any further remarks. What is best for patients is the best for everyone. We should not waste any efforts unless they are actually needed to improve the quality of life of heart-failure patients.

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Incorporation of Electronics within a Compact, Fully Implanted Left Ventricular Assist Device

Cited by 7 publications

References 7 publications

Design Rationale and Preclinical Evaluation of the HeartMate 3 Left Ventricular Assist System for Hemocompatibility

Design Rationale and Preclinical Evaluation of the HeartMate 3 Left Ventricular Assist System for Hemocompatibility

Computational Fluid Dynamics Analysis to Determine Shear Stresses and Rates in a Centrifugal Left Ventricular Assist Device

Third‐generation Blood Pumps With Mechanical Noncontact Magnetic Bearings

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