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In Vitro Evaluation of an Immediate Response Starling‐Like Controller for Dual Rotary Blood Pumps
Author(s) -
Stephens Andrew F.,
Stevens Michael C.,
Gregory Shaun D.,
Kleinheyer Matthias,
Salamonsen Robert F.
Publication year - 2017
Publication title -
artificial organs
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.684
H-Index - 76
eISSN - 1525-1594
pISSN - 0160-564X
DOI - 10.1111/aor.12962
Subject(s) - preload , cardiac output , starling , cardiology , venous return curve , ventricular assist device , medicine , vascular resistance , suction , frank–starling law of the heart , circulatory system , central venous pressure , mean circulatory filling pressure , heart failure , contractility , hemodynamics , blood pressure , heart rate , stroke volume , ejection fraction , mechanical engineering , engineering
Rotary ventricular assist devices (VADs) are used to provide mechanical circulatory support. However, their lack of preload sensitivity in constant speed control mode (CSC) may result in ventricular suction or venous congestion. This is particularly true of biventricular support, where the native flow‐balancing Starling response of both ventricles is diminished. It is possible to model the Starling response of the ventricles using cardiac output and venous return curves. With this model, we can create a Starling‐like physiological controller (SLC) for VADs which can automatically balance cardiac output in the presence of perturbations to the circulation. The comparison between CSC and SLC of dual HeartWare HVADs using a mock circulation loop to simulate biventricular heart failure has been reported. Four changes in cardiovascular state were simulated to test the controller, including a 700 m L reduction in circulating fluid volume, a total loss of left and right ventricular contractility, reduction in systemic vascular resistance ( S V R ) from 1300 to 600 d y n e s / cm 5, and an elevation in pulmonary vascular resistance ( P V R ) from 100 to 300 d y n e s / cm 5. SLC maintained the left and right ventricular volumes between 69–214 m L and 29–182 m L , respectively, for all tests, preventing ventricular suction (ventricular volume = 0 m L ) and venous congestion (atrial pressures > 20 m m H g ). Cardiac output was maintained at sufficient levels by the SLC, with systemic and pulmonary flow rates maintained above 3.14 L / m i n for all tests. With the CSC, left ventricular suction occurred during reductions in SVR, elevations in PVR, and reduction in circulating fluid simulations. These results demonstrate a need for a physiological control system and provide adequate in vitro validation of the immediate response of a SLC for biventricular support.