A Review of Leakage Flow in Centrifugal Blood Pumps

Chan, W.K.; Wong, Y. W.

doi:10.1111/j.1525-1594.2006.00225.x

Cited by 9 publications

(7 citation statements)

References 9 publications

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“…Speed modulation was only used in the outflow banding mode to ensure minimum pump speed remained within the speed limits of the VentrAssist device. Operating the pump below the designed speeds may promote thrombus formation and impeller touch down in pumps with hydrodynamic bearings . Meanwhile, our study only evaluated speed modulation with a VentrAssist pump, which is no longer commercially available.…”

Section: Discussionmentioning

confidence: 99%

Pulmonary Valve Opening With Two Rotary Left Ventricular Assist Devices for Biventricular Support

Nestler

Kleinheyer

et al. 2017

Artificial Organs

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Right ventricular failure is a common complication associated with rotary left ventricular assist device (LVAD) support. Currently, there is no clinically approved long-term rotary right ventricular assist device (RVAD). Instead, clinicians have implanted a second rotary LVAD as RVAD in biventricular support. To prevent pulmonary hypertension, the RVAD must be operated by either reducing pump speed or banding the outflow graft. These modes differ in hydraulic performance, which may affect the pulmonary valve opening (PVO) and subsequently cause fusion, valvular insufficiency, and thrombus formation. This study aimed to compare PVO with the RVAD operated at reduced speed or with a banded outflow graft. Baseline conditions of systemic normal, hypo, and hypertension with severe biventricular failure were simulated in a mock circulation loop. Biventricular support was provided with two rotary VentrAssist LVADs with cardiac output restored to 5 L/min in banded outflow and reduced speed conditions, and systemic and pulmonary vascular resistances (PVR) were manipulated to determine the range of conditions that allowed PVO without causing left ventricular suction. Finally, RVAD sine wave speed modulation (±550 rpm) strategies (co- and counter-pulsation) were implemented to observe the effect on PVO. For each condition, outflow banding had higher PVR (97 ± 20 dyne/s/cm higher) for when the pulmonary valve closed compared to reduced speed. In addition, counter-pulsation demonstrated greater PVO than co-pulsation and constant speed. For the purpose of reducing the risks of pulmonary valve insufficiency, fusion, and thrombotic event, this study recommends a RVAD with a steeper H-Q gradient by banding and further exploration of RVAD speed modulation.

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Section: Discussionmentioning

confidence: 99%

Pulmonary Valve Opening With Two Rotary Left Ventricular Assist Devices for Biventricular Support

Nestler

Kleinheyer

et al. 2017

Artificial Organs

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“…(8), a reduction in clearance gap size decreases the leakage flow rate, essentially improving pump efficiency. A higher level of pump performance for smaller clearance gaps has also been reported using the method of dimensional analysis (9).…”

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confidence: 88%

Prediction of Leakage Flow in a Shrouded Centrifugal Blood Pump

2010

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This article proposes a phenomenological model to predict the leakage flow in the clearance gap of shrouded centrifugal blood pumps. A good washout in the gap clearance between the rotating impeller surfaces and volute casing is essential to avoid thrombosis. However, excessive leakage flow will result in higher fluid shear stress that may lead to hemolysis. Computational fluid dynamics (CFD) analysis was performed to investigate the leakage flow in a miniaturized shrouded centrifugal blood pump operating at a speed of 2000 rpm. Based on an analytical model derived earlier, a phenomenological model is proposed to predict the leakage flow. The leakage flow rate is found to be proportional to h(α) , where h is the gap size and the exponent α ranges from 2.955 to 3.15 for corresponding gap sizes of 0.2-0.5 mm. In addition, it is observed that α is a linear function of the gap size h. The exponent α compensates for the variation of pressure difference along the circumferential direction as well as inertia effects that are dominant for larger gap clearances. The proposed model displays good agreement with computational results. The CFD analysis also showed that for larger gap sizes, the total leakage flow rate is of the same order of magnitude as the operating flow rate, thus suggesting low volumetric efficiency.

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“…Weng‐Kong Chan and Yew‐Wah Wong (20) of the Nanyang Technological University (Singapore) investigated, using dimensional analysis, the functional relationship between the leakage flow (for washout) in a centrifugal blood pump and various parameters that affect it. Results showed that pump performances with a smaller gap clearance were superior compared with those of pumps with larger gap clearances but of similar design.…”

Section: Cardiac Support and Blood Pumpsmentioning

confidence: 99%

Artificial Organs 2006: A Year in Review

Malchesky¹

2007

Artificial Organs

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A Review of Leakage Flow in Centrifugal Blood Pumps

Cited by 9 publications

References 9 publications

Pulmonary Valve Opening With Two Rotary Left Ventricular Assist Devices for Biventricular Support

Pulmonary Valve Opening With Two Rotary Left Ventricular Assist Devices for Biventricular Support

Prediction of Leakage Flow in a Shrouded Centrifugal Blood Pump

Artificial Organs 2006: A Year in Review

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