Effects of Pulsatile- and Continuous-flow Left Ventricular Assist Devices on Left Ventricular Unloading

García, Santiago Rodríguez; Kandar, Forum; Boyle, Andrew; Colvin-Adams, Monica; Lliao, Kenneth; Joyce, Lyle D.; John, Ranjit

doi:10.1016/j.healun.2007.12.001

Cited by 77 publications

(44 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Accomplishing this goal while maintaining evolutionarily preserved physiology, i.e., pulsatility, may influence the ability of these devices to provide beneficial and durable support for the advanced heart failure patient. Comparative efficacy of pulsatile-and continuous-flow VADs have extensively documented their effects on ventricular unloading [19,20], hemodynamics [21,22], end organ function, and microcirculation [23], as well as vascular reactivity [24]. While continuous-flow devices are not pulsatile by design, we show that some designs exhibit greater induced pulsatility than others.…”

Section: Discussionmentioning

confidence: 67%

In Vitro Pulsatility Analysis of Axial-Flow and Centrifugal-Flow Left Ventricular Assist Devices

Stanfield

Selzman

2013

Journal of Biomechanical Engineering

View full text Add to dashboard Cite

Recently, continuous-flow ventricular assist devices (CF-VADs) have supplanted older, pulsatile-flow pumps, for treating patients with advanced heart failure. Despite the excellent results of the newer generation devices, the effects of long-term loss of pulsatility remain unknown. The aim of this study is to compare the ability of both axial and centrifugal continuous-flow pumps to intrinsically modify pulsatility when placed under physiologically diverse conditions. Four VADs, two axial-and two centrifugal-flow, were evaluated on a mock circulatory flow system. Each VAD was operated at a constant impeller speed over three hypothetical cardiac conditions: normo-tensive, hypertensive, and hypotensive. Pulsatility index (PI) was compared for each device under each condition. Centrifugal-flow devices had a higher PI than that of axial-flow pumps. Under normo-tension, flow PI was 0.98 6 0.03 and 1.50 6 0.02 for the axial and centrifugal groups, respectively (p < 0.01). Under hypertension, flow PI was 1.90 6 0.16 and 4.21 6 0.29 for the axial and centrifugal pumps, respectively (p ¼ 0.01). Under hypotension, PI was 0.73 6 0.02 and 0.78 6 0.02 for the axial and centrifugal groups, respectively (p ¼ 0.13). All tested CF-VADs were capable of maintaining some pulsatile-flow when connected in parallel with our mock ventricle. We conclude that centrifugal-flow devices outperform the axial pumps from the basis of PI under tested conditions.

show abstract

Section: Discussionmentioning

confidence: 67%

In Vitro Pulsatility Analysis of Axial-Flow and Centrifugal-Flow Left Ventricular Assist Devices

Stanfield

Selzman

2013

Journal of Biomechanical Engineering

View full text Add to dashboard Cite

show abstract

“…Their constant rotary speed results in a reduced aortic pulsatility [30]. The question whether and to what extent pulsatility is required in the human body has been highly disputed since the introduction of turbodynamic VADs (tVADs) [10,19,30,35]. Several studies have compared the ventricular unloading between pulsatile and non-pulsatile VAD support.…”

Section: Introductionmentioning

confidence: 99%

“…Several studies have compared the ventricular unloading between pulsatile and non-pulsatile VAD support. Garcia et al [10] found no difference in the level of unloading between pVAD and tVAD support, while Klotz et al [19] observed a similar degree of left ventricular (LV) pressure unloading but a significantly higher degree of volume unloading with a pVAD [19]. The general consensus is that pulsatile flow offers potential benefits over non-pulsatile flow [29,30] including increased end organ perfusion [8], better unloading of the LV [23], less risk of right ventricular failure [17], mitigation of aortic valve stenosis and improved vascular remodeling [15], better chances for recovery [20] and reduction of gastrointestinal bleeding [7,30] when compared with a continuous flow support.…”

Section: Introductionmentioning

confidence: 99%

High-frequency operation of a pulsatile VAD – a simulation study

Rebholz

Amacher

Petrou

et al. 2017

Biomedical Engineering / Biomedizinische Technik

View full text Add to dashboard Cite

Ventricular assist devices (VADs) are mechanical blood pumps that are clinically used to treat severe heart failure. Pulsatile VADs (pVADs) were initially used, but are today in most cases replaced by turbodynamic VADs (tVADs). The major concern with the pVADs is their size, which prohibits full pump body implantation for a majority of patients. A reduction of the necessary stroke volume can be achieved by increasing the stroke frequency, while maintaining the same level of support capability. This reduction in stroke volume in turn offers the possibility to reduce the pump's overall dimensions. We simulated a human cardiovascular system (CVS) supported by a pVAD with three different stroke rates that were equal, two-or threefold the heart rate (HR). The pVAD was additionally synchronized to the HR for better control over the hemodynamics and the ventricular unloading. The simulation results with a HR of 90 bpm showed that a pVAD stroke volume can be reduced by 71%, while maintaining an aortic pulse pressure (PP) of 30 mm Hg, avoiding suction events, reducing the ventricular stroke work (SW) and allowing the aortic valve to open. A reduction by 67% offers the additional possibility to tune the interaction between the pVAD and the CVS. These findings allow a major reduction of the pVAD's body size, while allowing the physician to tune the pVAD according to the patient's needs.

show abstract

“…Finally, Fig. 11 shows a comparison between experimental (hybrid) and clinical LVAD assistance results [26][27][28][29][30], including these parameters: CO tot , p as , p ap and p la . The data are presented in the form of percentage changes related to the same values in initial pathological conditions (for the hybrid model -Path.…”

Section: Resultsmentioning

confidence: 99%

A new hybrid (hydro-numerical) model of the circulatory system

Darowski¹,

Kozarski²,

Ferrari³

et al. 2013

Bulletin of the Polish Academy of Sciences: Technical Sciences

View full text Add to dashboard Cite

Abstract. The paper presents a hybrid (hydro-numerical) circulatory model built to be used as a complementary tool for clinical purposes. It was developed at the Institute of Biocybernetics and Biomedical Engineering -Polish Academy of Sciences (Poland) in co-operation with the Institute of Clinical Physiology -National Council of Research (Italy). Main advantages of the model are: 1) high accuracy and repeatability of parameters setting, characteristic of numerical solutions, 2) maximum flexibility achieved by implementing the largest possible number of the model's elements in the numerical way, 3) ability to test mechanical heart assist devices provided by special computer applications; in the model two physically different signal environments -numerical and hydraulic -are connected by special impedance transformers interfacing physical and numerical parts of the model; 4) eliminating flowmeters, as the voltage controlled flow sources embedded in the system provide information on flows.In vitro tests were performed to evaluate the circulatory model: a) modelling and simulation of physiological and pathological states parameters vs. left ventricular end-systolic elastance (E max l ) and rest volume (V o l ) variations, b) testing the effect of LVAD counterpulsation on circulatory hemodynamics and ventricular energetics; it resulted in the increase of total cardiac output (COLV tot) from pathological value 3.8 to 5.4 l·min −1 , mean aortic pressure mPas from 67.8 to 96.1 mmHg and in the decrease of left atrial pressure mP la from 15.7 to 7.7 mmHg and External Work nEW by 37.5%.The model was verified based on literature data.

show abstract

Effects of Pulsatile- and Continuous-flow Left Ventricular Assist Devices on Left Ventricular Unloading

Cited by 77 publications

References 19 publications

In Vitro Pulsatility Analysis of Axial-Flow and Centrifugal-Flow Left Ventricular Assist Devices

In Vitro Pulsatility Analysis of Axial-Flow and Centrifugal-Flow Left Ventricular Assist Devices

High-frequency operation of a pulsatile VAD – a simulation study

A new hybrid (hydro-numerical) model of the circulatory system

Contact Info

Product

Resources

About