In vitro and in vivo characterization of three different modes of pump operation when using a left ventricular assist device as a right ventricular assist device

Stevens, Michael C., Gregory, Shaun D., Nestler, Frank, Thomson, Bruce, Choudhary, Jivesh, Garlick, Bruce, Pauls, Jo P., Fraser, John F. and Timms, Daniel (2014) In vitro and in vivo characterization of three different modes of pump operation when using a left ventricular assist device as a right ventricular assist device. Artificial Organs, 38 11: 931-939. doi:10.1111/aor.12289


Author Stevens, Michael C.
Gregory, Shaun D.
Nestler, Frank
Thomson, Bruce
Choudhary, Jivesh
Garlick, Bruce
Pauls, Jo P.
Fraser, John F.
Timms, Daniel
Title In vitro and in vivo characterization of three different modes of pump operation when using a left ventricular assist device as a right ventricular assist device
Journal name Artificial Organs   Check publisher's open access policy
ISSN 0160-564X
1525-1594
Publication date 2014-03-24
Year available 2014
Sub-type Article (original research)
DOI 10.1111/aor.12289
Volume 38
Issue 11
Start page 931
End page 939
Total pages 9
Place of publication Hoboken, NJ, United States
Publisher Wiley-Blackwell Publishing
Collection year 2015
Language eng
Abstract Dual rotary left ventricular assist devices (LVADs) have been used clinically to support patients with biventricular failure. However, due to the lower vascular resistance in the pulmonary circulation compared with its systemic counterpart, excessively high pulmonary flow rates are expected if the right ventricular assist device (RVAD) is operated at its design LVAD speed. Three possible approaches are available to match the LVAD to the pulmonary circulation: operating the RVAD at a lower speed than the LVAD (mode 1), operating both pumps at their design speeds (mode 2) while relying on the cardiovascular system to adapt, and operating both pumps at their design speeds while restricting the diameter of the RVAD outflow graft (mode 3). In this study, each mode was characterized using in vitro and in vivo models of biventricular heart failure supported with two VentrAssist LVADs. The effect of each mode on arterial and atrial pressures and flow rates for low, medium, and high vascular resistances and three different contractility levels were evaluated. The amount of speed/diameter adjustment required to accommodate elevated pulmonary vascular resistance (PVR) during support with mode 3 was then investigated. Mode 1 required relatively low systemic vascular resistance to achieve arterial pressures less than 100mmHg in vitro, resulting in flow rates greater than 6L/min. Mode 2 resulted in left atrial pressures above 25mmHg, unless left heart contractility was near-normal. In vitro, mode 3 resulted in expected arterial pressures and flow rates with an RVAD outflow diameter of 6.5mm. In contrast, all modes were achievable in vivo, primarily due to higher RVAD outflow graft resistance (more than 500dyn·s/cm5), caused by longer cannula. Flow rates could be maintained during instances of elevated PVR by increasing the RVAD speed or expanding the outflow graft diameter using an externally applied variable graft occlusion device. In conclusion, suitable hemodynamics could be produced by either restricting or not restricting the right outflow graft diameter; however, the latter required an operation of the RVAD at lower than design speed. Adjustments in outflow restriction and/or RVAD speed are recommended to accommodate varying PVR.
Keyword Biventricular assist device
Rotary pump
Heart failure
Pulmonary vascular resistance
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published online ahead of print 24 March 2014.

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
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