Body Position and Activity, But Not Heart Rate, Affect Pump Flows in Patients With Continuous-Flow Left Ventricular Assist Devices

Muthiah, K.; Otton, James; Robson, D.; Walker, R.; Tay, Andre; Macdonald, P.; Keogh, Anne; Kotlyar, Eugene; Granger, Emily; Dhital, K.; Spratt, Phillip; Jansz, P.; Hayward, Christopher

doi:10.1016/j.jchf.2014.02.008

Cited by 38 publications

(21 citation statements)

References 24 publications

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“…(31). Additionally, heart rate is a potent facilitator of the competing mechanism and no correlation between ∆HR and ∆Q LVAD existed, as mentioned in reference (28).…”

Section: Discussionmentioning

confidence: 98%

“…The main mechanism that leads to an increase in LVAD output at constant speed is a decrease in the pump's head pressure. The key determinates for a decreased pump head are increasing venous return (28) and LV contractility or reducing afterload, for example, due to vasodilation. These effects occur as a cardiovascular response during exercise depending on exercise intensity and duration (15,18 The results from the current study suggest that this increase in pump flow (when an LVAD is driven at constant speed) is moderate and similar for both maximal and submaximal exercises.…”

Section: Discussionmentioning

confidence: 99%

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LVAD Pump Flow Does Not Adequately Increase With Exercise

Gross

Marko²,

Mikl³

et al. 2018

Artificial Organs

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Left ventricular assist devices (LVADs) restore cardiovascular circulatory demand at rest with a spontaneous increase in pump flow to exercise. The relevant contribution of cardiac output provided by the LVAD and ejected through the aortic valve for exercises of different intensities has been barely investigated in patients. The hypothesis of this study was that different responses in continuous recorded pump parameters occur for maximal and submaximal intensity exercises and that the pump flow change has an impact on the oxygen uptake at peak exercise (pVO ). Cardiac and pump parameters such as LVAD flow rate (Q ), heart rate (HR), and aortic valve (AV) opening were analyzed from continuously recorded LVAD data during physical exercises of maximal (bicycle ergometer test) and submaximal intensities (6-min walk test and regular trainings). During all exercise sessions, the LVAD speed was kept constant. Cardiac and pump parameter responses of 16 patients for maximal and submaximal intensity exercises were similar for Q : +0.89 ± 0.52 versus +0.59 ± 0.38 L/min (P = 0.07) and different for HR: +20.4 ± 15.4 versus +7.7 ± 5.8 bpm (P < 0.0001) and AV-opening with 71% versus 23% of patients (P < 0.0001). Multi-regression analysis with pVO (R = 0.77) showed relation to workload normalized by bodyweight (P = 0.0002), HR response (P = 0.001), AV-opening (P = 0.02), and age (P = 0.06) whereas the change in Q was irrelevant. Constant speed LVADs provide inadequate support for maximum intensity exercises. AV-opening and improvements in HR show an important role for higher exercise capacities and reflect exercise intensities. Changes in pump flow do not impact pVO and are independent of AV-opening and response in HR. An LVAD speed control may lead to adequate left ventricular support during strenuous physical activities.

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“…(31). Additionally, heart rate is a potent facilitator of the competing mechanism and no correlation between ∆HR and ∆Q LVAD existed, as mentioned in reference (28).…”

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

LVAD Pump Flow Does Not Adequately Increase With Exercise

Gross

Marko²,

Mikl³

et al. 2018

Artificial Organs

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show abstract

“…Sustained passive elevation of the legs may provide a transient increase in venous return and help to maintain perfusion until the fluid has been administered. 39 40 If passive leg raising is followed by a transient increase in flow rate through the LVAD (sometimes for less than a minute), this supports the likely need for intravenous fluid. Positive responses to fluid administration include an increase in the displayed LVAD flow rate and clinical evidence of improved circulation.…”

Section: Methodsmentioning

confidence: 89%

Algorithms to guide ambulance clinicians in the management of emergencies in patients with implanted rotary left ventricular assist devices

et al. 2017

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Advances in left ventricular assist device (LVAD) therapy have resulted in increasing numbers of adult LVAD recipients in the community. However, device failure, stroke, bleeding, LVAD thrombosis and systemic infection can be life-threatening emergencies. Currently, four LVAD systems are implanted in six UK transplant centres, each of which provides device-specific information to local emergency services. This has resulted in inconsistent availability and content of information with the risks of delayed or inappropriate decision-making. In order to improve patient safety, a consortium of UK healthcare professionals with expertise in LVADs developed universally applicable prehospital emergency algorithms. Guidance was framed as closely as possible on the standard ABCDE approach to the assessment of critically ill patients.

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“…The differential pressure is determined by preload and afterload, with a wider pressure differential-either a result of increased afterload or decreased preload-resulting in a reduction in flow (9). The differential pressure is determined by preload and afterload, with a wider pressure differential-either a result of increased afterload or decreased preload-resulting in a reduction in flow (9).…”

Section: Discussionmentioning

confidence: 99%

“…Flow generated by a continuous LVAD is dependent on a number of variables-most importantly set pump speed-but also the differential pressure across the pump. The differential pressure is determined by preload and afterload, with a wider pressure differential-either a result of increased afterload or decreased preload-resulting in a reduction in flow (9). As such, CI is dependent on right ventricular (RV) function and the volume of blood delivered to the LV as well as the afterload to which the LVAD is exposed (10).…”

Section: Discussionmentioning

confidence: 99%

Cardiac Index Declines During Long‐Term Left Ventricular Device Support

Kalathiya¹,

Houston²,

Chaisson³

et al. 2016

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To investigate longitudinal trends in valvular and ventricular function with long-term left ventricular assist device (LVAD) therapy, we analyzed hemodynamic and echocardiographic data of patients with at least 2 years of continuous LVAD support. All 130 patients who underwent HeartMate II implantation at our institution between 2005 and 2012 were reviewed. Twenty patients had hemodynamic and echocardiographic evaluations in both the early (0-6 months) and late (2-3 years) postoperative period. Patients on inotropic therapy or temporary mechanical support were excluded. The average times of early and late hemodynamic evaluations were 59 ± 41 days and 889 ± 160 days, respectively. Cardiac index (CI) declined by an average of 0.4 L/min/m (P = 0.04) with concomitant increase in pulmonary capillary wedge pressure (PCWP; P = 0.02). The right atrial pressure to PCWP (RAP:PCWP) ratio decreased during LVAD support suggesting improvement in right ventricular function. While there was an increase in degree of aortic insufficiency (AI) at the late follow-up period (P = 0.008), dichotomization by median decline in CI (-0.4 L/min/m ) indicated no difference in prevalence of AI among the groups. CI declined in patients with HeartMate II after 2 years of continuous support. An increase in preload and afterload was observed in those with the greatest decline in CI.

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Body Position and Activity, But Not Heart Rate, Affect Pump Flows in Patients With Continuous-Flow Left Ventricular Assist Devices

Cited by 38 publications

References 24 publications

LVAD Pump Flow Does Not Adequately Increase With Exercise

LVAD Pump Flow Does Not Adequately Increase With Exercise

Algorithms to guide ambulance clinicians in the management of emergencies in patients with implanted rotary left ventricular assist devices

Cardiac Index Declines During Long‐Term Left Ventricular Device Support

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