Relation Between Pressure and Volume Unloading During Ramp Testing in Patients Supported with a Continuous-Flow Left Ventricular Assist Device

Jung, Mette Holme; Hassager, Christian; Balling, Louise; Russell, Stuart D.; Boesgaard, S.; Gustafsson, Finn

doi:10.1097/mat.0000000000000194

Cited by 26 publications

(22 citation statements)

References 14 publications

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“…For HF+VAD, parameters al and bl were estimated fitting the data of 10 patients with a continuous-flow assist device [13]: data reflect the capillary venous wedge pressure and the end-diastolic ventricular volume estimated from the end-diastolic diameter using the Teicholz formula (see Fig 2-A). An exponential curve fitting was used to estimate the diastolic stiffness from these data as shown in in Fig 2-A.…”

Section: Methodsmentioning

confidence: 99%

“…The continuous line indicates the exponential function that was obtained by fitting the data (●) taken from Jung et al [13]. Symbol (x) indicates data excluded from the analysis.…”

Section: Methodsmentioning

confidence: 99%

“…Symbol (x) indicates data excluded from the analysis. (B): Comparison between the ventricular stiffness calculated in panel (A) and the stiffness in other pathophysiological conditions taken from literature [12,13,15]. From left to right curves refer to patients with: healthy condition, ischemic cardiomyopathy and a pulsatile VAD, dilated cardiomyopathy and a pulsatile VAD, continuous-flow VAD, ischemic cardiomyopathy, scheduled for ventricular restoration, mitral regurgitation, dilated cardiomyopathy.…”

Section: Methodsmentioning

confidence: 99%

“…For HF+VAD Ras was calculated considering data from [3,5,13], Rap averaging data from [3,5]. Ras was then split into the resistance of upper body, kidneys, splanchnic circulation and lower limbs as reported in [8].…”

Section: Methodsmentioning

confidence: 99%

“…From a physiological point of view, Pset represents the equilibrium value and it was characterized in the simulator at rest condition: for HF we averaged the mean systemic pressure at rest taken from [3,16,17,18], for HF+VAD we averaged the data of [3,5,13]. During exercise Pset automatically increases due to the “baroreflex resetting phenomenon” that progressively shifts the baroreflex control towards higher pressure levels.…”

Section: Methodsmentioning

confidence: 99%

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Exercise physiology with a left ventricular assist device: Analysis of heart-pump interaction with a computational simulator

et al. 2017

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Patients with a Ventricular Assist Device (VAD) are hemodynamically stable but show an impaired exercise capacity. Aim of this work is to identify and to describe the limiting factors of exercise physiology with a VAD. We searched for data concerning exercise in heart failure condition and after VAD implantation from the literature. Data were analyzed by using a cardiorespiratory simulator that worked as a collector of inputs coming from different papers. As a preliminary step the simulator was used to reproduce the evolution of hemodynamics from rest to peak exercise (ergometer cycling) in heart failure condition. Results evidence an increase of cardiac output of +2.8 l/min and a heart rate increase to 67% of the expected value. Then, we simulated the effect of a continuous-flow VAD at both rest and exercise. Total cardiac output increases of +3.0 l/min (+0.9 l/min due to the VAD and +2.1 l/min to the native ventricle). Since the left ventricle works in a non-linear portion of the diastolic stiffness line, we observed a consistent increase of pulmonary capillary wedge pressure (from 14 to 20 mmHg) for a relatively small increase of end-diastolic volume (from 182 to 189 cm3). We finally increased VAD speed during exercise to the maximum possible value and we observed a reduction of wedge pressure (-4.5 mmHg), a slight improvement of cardiac output (8.0 l/min) and a complete unloading of the native ventricle. The VAD can assure a proper hemodynamics at rest, but provides an insufficient unloading of the left ventricle and does not prevent wedge pressure from rising during exercise. Neither the VAD provides major benefits during exercise in terms of total cardiac output, which increases to a similar extend to an unassisted heart failure condition. VAD speed modulation can contribute to better unload the ventricle but the maximal flow reachable with the current devices is below the cardiac output observed in a healthy heart.

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Section: Methodsmentioning

confidence: 99%

“…The continuous line indicates the exponential function that was obtained by fitting the data (●) taken from Jung et al [13]. Symbol (x) indicates data excluded from the analysis.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Exercise physiology with a left ventricular assist device: Analysis of heart-pump interaction with a computational simulator

et al. 2017

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Physiology of Continuous‐Flow Left Ventricular Assist Device Therapy

Rosenbaum

Antaki

Behfar

et al. 2021

Comprehensive Physiology

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The expanding use of continuous-flow left ventricular assist devices (CF-LVADs) for end-stage heart failure warrants familiarity with the physiologic interaction of the device with the native circulation. Contemporary devices utilize predominantly centrifugal flow and, to a lesser extent, axial flow rotors that vary with respect to their intrinsic flow characteristics. Flow can be manipulated with adjustments to preload and afterload as in the native heart, and ascertainment of the predicted effects is provided by differential pressure-flow (H-Q) curves or loops. Valvular heart disease, especially aortic regurgitation, may significantly affect adequacy of mechanical support. In contrast, atrioventricular and ventriculoventricular timing is of less certain significance. Although beneficial effects of device therapy are typically seen due to enhanced distal perfusion, unloading of the left ventricle and atrium, and amelioration of secondary pulmonary hypertension, negative effects of CF-LVAD therapy on right ventricular filling and function, through right-sided loading and septal interaction, can make optimization challenging. Additionally, a lack of pulsatile energy provided by CF-LVAD therapy has physiologic consequences for end-organ function and may be responsible for a series of adverse effects. Rheological effects of intravascular pumps, especially shear stress exposure, result in platelet activation and hemolysis, which may result in both thrombotic and hemorrhagic consequences. Development of novel solutions for untoward device-circulatory interactions will facilitate hemodynamic support while mitigating adverse events.

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Validation of non‐invasive ramp testing for HeartMate 3

et al. 2020

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Aims Ramp testing in the postoperative period can be used to optimize left ventricular assist device (LVAD) speed for optimal left ventricular (LV) unloading. We tested the hypothesis that a non-invasive echocardiographic ramp test post-HeartMate 3 implantation improves LV unloading immediately after and 1-3 months after as compared with before the test. We also tested a secondary hypothesis that speed adjustments during echocardiography-guided ramp testing do not worsen right ventricular (RV) function immediately after and 1-3 months after. Methods and resultsWe retrospectively reviewed data from patients who underwent an echocardiographic ramp test. A total of 14 out of 19 patients were clinically stable and were enrolled. Adequate LV unloading was defined as no more than mild mitral regurgitation, and intermittent aortic valve (AV) opening or closed AV, and reduction of left ventricular end-diastolic diameter (LVEDD); and for the follow-up measurement, decreased NT-proBNP. Median (interquartile range) time from implantation to ramp test was 27 (16; 56) days, and median time from ramp test to follow-up echocardiography was 55 (47; 102) days. Median LVAD speed achieved during ramp testing was 5550 (5375; 6025) revolutions per minute (rpm), and median final LVAD speed was 5200 (5000; 5425) rpm. Ramp testing resulted in final LVAD speed increase in 11 (79%) patients and a median net change of 200 (200; 300) rpm. Speed adjustments after ramp testing resulted in improved LVAD unloading that was achieved in additional 3 (21%) patients who were not originally optimized. RV function did not worsen significantly during ramp testing or at final LVAD speed. Conclusions The echocardiographic ramp test allowed LVAD speed adjustment and optimization and improved LV unloading during ramp testing and at final speed with no evidence of worsening of RV function.

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Relation Between Pressure and Volume Unloading During Ramp Testing in Patients Supported with a Continuous-Flow Left Ventricular Assist Device

Cited by 26 publications

References 14 publications

Exercise physiology with a left ventricular assist device: Analysis of heart-pump interaction with a computational simulator

Exercise physiology with a left ventricular assist device: Analysis of heart-pump interaction with a computational simulator

Physiology of Continuous‐Flow Left Ventricular Assist Device Therapy

Validation of non‐invasive ramp testing for HeartMate 3

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