A Starling-like total work controller for rotary blood pumps

an in vitro evaluation

Eric Lee-Jan Wu, Michael Charles Stevens, Frank Nestler, Jo P. Pauls, Andrew Bradley, John Fraser, Geoff Tansley, Shaun Gregory

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Due to improved durability and survival rates, rotary blood pumps (RBPs) are the preferred left ventricular assist device when compared to volume displacement pumps. However, when operated at constant speed, RBPs lack a volume balancing mechanism which may result in left ventricular suction and sub-optimal ventricular unloading. Starling-like controllers have previously been developed to balance circulatory volumes, however they do not consider ventricular workload as a feedback and may have limited sensitivity to adjust RBP workload when ventricular function deteriorates or improves. To address this, we aimed to develop a Starling-like total work controller (SL-TWC) that matched the energy output of a healthy heart by adjusting RBP hydraulic work based on measured left ventricular stroke work and ventricular preload. In a mock circulatory loop, the SL-TWC was evaluated using a HeartWare HVAD in a range of simulated patient conditions. These conditions included changes in systemic hyper- and hypo-tension, pulmonary hypertension, blood circulatory volume, exercise and improvement and deterioration of ventricular function by increasing and decreasing ventricular contractility. The SL-TWC was compared to constant speed control where RBP speed was set to restore cardiac output to 5.0 L min-1 at rest. Left ventricular suction occurred with constant speed control during pulmonary hypertension but was prevented with the SL-TWC. During simulated exercise, the SL-TWC demonstrated reduced LVSW (0.51 J) and greater RBP flow (9.2 L min-1 ) compared to constant speed control (LVSW: 0.74 J and RBP flow: 6.4 L min-1 ). In instances of increased ventricular contractility, the SL-TWC reduced RBP hydraulic work, whilst maintaining cardiac output similar to the rest condition. In comparison, constant speed overworked and increased cardiac output. The SL-TWC balanced circulatory volumes by mimicking the Starling mechanism, whilst also considering changes in ventricular workload. Compared to constant speed control, the SL-TWC may reduce complications associated with volume imbalances, adapt to changes in ventricular function and improve patient quality of life.
Original languageEnglish
Number of pages36
JournalArtificial Organs
DOIs
Publication statusAccepted/In press - 13 Sep 2019
Externally publishedYes

Cite this

Wu, E. L-J., Stevens, M. C., Nestler, F., Pauls, J. P., Bradley, A., Fraser, J., ... Gregory, S. (Accepted/In press). A Starling-like total work controller for rotary blood pumps: an in vitro evaluation. Artificial Organs. https://doi.org/10.1111/aor.13570
Wu, Eric Lee-Jan ; Stevens, Michael Charles ; Nestler, Frank ; Pauls, Jo P. ; Bradley, Andrew ; Fraser, John ; Tansley, Geoff ; Gregory, Shaun. / A Starling-like total work controller for rotary blood pumps : an in vitro evaluation. In: Artificial Organs. 2019.
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abstract = "Due to improved durability and survival rates, rotary blood pumps (RBPs) are the preferred left ventricular assist device when compared to volume displacement pumps. However, when operated at constant speed, RBPs lack a volume balancing mechanism which may result in left ventricular suction and sub-optimal ventricular unloading. Starling-like controllers have previously been developed to balance circulatory volumes, however they do not consider ventricular workload as a feedback and may have limited sensitivity to adjust RBP workload when ventricular function deteriorates or improves. To address this, we aimed to develop a Starling-like total work controller (SL-TWC) that matched the energy output of a healthy heart by adjusting RBP hydraulic work based on measured left ventricular stroke work and ventricular preload. In a mock circulatory loop, the SL-TWC was evaluated using a HeartWare HVAD in a range of simulated patient conditions. These conditions included changes in systemic hyper- and hypo-tension, pulmonary hypertension, blood circulatory volume, exercise and improvement and deterioration of ventricular function by increasing and decreasing ventricular contractility. The SL-TWC was compared to constant speed control where RBP speed was set to restore cardiac output to 5.0 L min-1 at rest. Left ventricular suction occurred with constant speed control during pulmonary hypertension but was prevented with the SL-TWC. During simulated exercise, the SL-TWC demonstrated reduced LVSW (0.51 J) and greater RBP flow (9.2 L min-1 ) compared to constant speed control (LVSW: 0.74 J and RBP flow: 6.4 L min-1 ). In instances of increased ventricular contractility, the SL-TWC reduced RBP hydraulic work, whilst maintaining cardiac output similar to the rest condition. In comparison, constant speed overworked and increased cardiac output. The SL-TWC balanced circulatory volumes by mimicking the Starling mechanism, whilst also considering changes in ventricular workload. Compared to constant speed control, the SL-TWC may reduce complications associated with volume imbalances, adapt to changes in ventricular function and improve patient quality of life.",
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A Starling-like total work controller for rotary blood pumps : an in vitro evaluation. / Wu, Eric Lee-Jan; Stevens, Michael Charles; Nestler, Frank; Pauls, Jo P.; Bradley, Andrew; Fraser, John; Tansley, Geoff; Gregory, Shaun.

In: Artificial Organs, 13.09.2019.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - A Starling-like total work controller for rotary blood pumps

T2 - an in vitro evaluation

AU - Wu, Eric Lee-Jan

AU - Stevens, Michael Charles

AU - Nestler, Frank

AU - Pauls, Jo P.

AU - Bradley, Andrew

AU - Fraser, John

AU - Tansley, Geoff

AU - Gregory, Shaun

PY - 2019/9/13

Y1 - 2019/9/13

N2 - Due to improved durability and survival rates, rotary blood pumps (RBPs) are the preferred left ventricular assist device when compared to volume displacement pumps. However, when operated at constant speed, RBPs lack a volume balancing mechanism which may result in left ventricular suction and sub-optimal ventricular unloading. Starling-like controllers have previously been developed to balance circulatory volumes, however they do not consider ventricular workload as a feedback and may have limited sensitivity to adjust RBP workload when ventricular function deteriorates or improves. To address this, we aimed to develop a Starling-like total work controller (SL-TWC) that matched the energy output of a healthy heart by adjusting RBP hydraulic work based on measured left ventricular stroke work and ventricular preload. In a mock circulatory loop, the SL-TWC was evaluated using a HeartWare HVAD in a range of simulated patient conditions. These conditions included changes in systemic hyper- and hypo-tension, pulmonary hypertension, blood circulatory volume, exercise and improvement and deterioration of ventricular function by increasing and decreasing ventricular contractility. The SL-TWC was compared to constant speed control where RBP speed was set to restore cardiac output to 5.0 L min-1 at rest. Left ventricular suction occurred with constant speed control during pulmonary hypertension but was prevented with the SL-TWC. During simulated exercise, the SL-TWC demonstrated reduced LVSW (0.51 J) and greater RBP flow (9.2 L min-1 ) compared to constant speed control (LVSW: 0.74 J and RBP flow: 6.4 L min-1 ). In instances of increased ventricular contractility, the SL-TWC reduced RBP hydraulic work, whilst maintaining cardiac output similar to the rest condition. In comparison, constant speed overworked and increased cardiac output. The SL-TWC balanced circulatory volumes by mimicking the Starling mechanism, whilst also considering changes in ventricular workload. Compared to constant speed control, the SL-TWC may reduce complications associated with volume imbalances, adapt to changes in ventricular function and improve patient quality of life.

AB - Due to improved durability and survival rates, rotary blood pumps (RBPs) are the preferred left ventricular assist device when compared to volume displacement pumps. However, when operated at constant speed, RBPs lack a volume balancing mechanism which may result in left ventricular suction and sub-optimal ventricular unloading. Starling-like controllers have previously been developed to balance circulatory volumes, however they do not consider ventricular workload as a feedback and may have limited sensitivity to adjust RBP workload when ventricular function deteriorates or improves. To address this, we aimed to develop a Starling-like total work controller (SL-TWC) that matched the energy output of a healthy heart by adjusting RBP hydraulic work based on measured left ventricular stroke work and ventricular preload. In a mock circulatory loop, the SL-TWC was evaluated using a HeartWare HVAD in a range of simulated patient conditions. These conditions included changes in systemic hyper- and hypo-tension, pulmonary hypertension, blood circulatory volume, exercise and improvement and deterioration of ventricular function by increasing and decreasing ventricular contractility. The SL-TWC was compared to constant speed control where RBP speed was set to restore cardiac output to 5.0 L min-1 at rest. Left ventricular suction occurred with constant speed control during pulmonary hypertension but was prevented with the SL-TWC. During simulated exercise, the SL-TWC demonstrated reduced LVSW (0.51 J) and greater RBP flow (9.2 L min-1 ) compared to constant speed control (LVSW: 0.74 J and RBP flow: 6.4 L min-1 ). In instances of increased ventricular contractility, the SL-TWC reduced RBP hydraulic work, whilst maintaining cardiac output similar to the rest condition. In comparison, constant speed overworked and increased cardiac output. The SL-TWC balanced circulatory volumes by mimicking the Starling mechanism, whilst also considering changes in ventricular workload. Compared to constant speed control, the SL-TWC may reduce complications associated with volume imbalances, adapt to changes in ventricular function and improve patient quality of life.

U2 - 10.1111/aor.13570

DO - 10.1111/aor.13570

M3 - Article

JO - Artificial Organs

JF - Artificial Organs

SN - 0160-564X

ER -