A desk-top computer model of the circulatory system for heart assistance simulation: effect of an LVAD on energetic relationships inside the left ventricle

Lazzari, Claudio De; Ferrari, G.; Mimmo, R.; Tosti, G.; Ambrosi, Davide Carlo

doi:10.1016/1350-4533(94)90022-1

Cited by 19 publications

(22 citation statements)

References 6 publications

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“…(9) coupled a cardiovascular system model, including the systemic circulation and the coronary circulation, and a pulsatile catheter pump type VAD model, to study the influence of the VAD on the native cardiovascular system. Other researchers (2,10) simplified the cardiovascular system into a Windkessel model or a Westkessel model combined with the left heart, while some researchers developed complete cardiovascular system models including both the systemic and pulmonary circulation (3,7,11–13). From the point of view of accuracy, the complete cardiovascular system model as well as the complete VAD model are necessary in the numerical simulation.…”

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confidence: 99%

Numerical Simulation of Cardiovascular Dynamics With Left Heart Failure and In‐series Pulsatile Ventricular Assist Device

Shi

Korakianitis

2006

Artificial Organs

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This article presents a numerical model for investigations of the human cardiovascular circulation system response, where the function of the impaired left ventricle is augmented by the pumping action of a pulsatile ventricular assist device (VAD) connected in series to the native heart. The numerical model includes a module for detailed heart valve dynamics, which helps to improve the accuracy of simulation in studying the pulsatile type VAD designs. Simulation results show that, for the case with left ventricular (LV) failure, the VAD support successfully compensates the impaired cardiovascular response, and greatly reduces the after-load of the diseased ventricle, thus assisting possible recovery of the ventricle from the diseased condition. The effects of these conditions on pulmonary circulation are also shown. To investigate the effect of different pumping-activation functions (VAD motion profiles) on the cardiovascular response, three different VAD motion profiles are investigated. The numerical results suggest that Hermitian type motion profiles (smooth curves skewed toward early systole) have the advantage of requiring minimum power to the VAD, and producing the minimum after-load to the left ventricle, minimum ventricular wall stress, and minimum ventricular work to the diseased ventricle; while sawtooth type motions need slightly more power input, and induce slightly increased aortic pressure in diastole, thus improving coronary perfusion.

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confidence: 99%

Numerical Simulation of Cardiovascular Dynamics With Left Heart Failure and In‐series Pulsatile Ventricular Assist Device

Shi

Korakianitis

2006

Artificial Organs

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“…Air out ow from a high-pressure tank as a pressure source (Pd) to a lower pressure tank as the ventricle represents ejection. Air out ow from the ventricle as a higher pressure tank to a vacuum source (Pv) as a lower pressure tank [9] describes lling. LVAD was placed between the left atrium and the aorta, while RVAD was between the right atrium and pulmonary artery.…”

Section: Cardiosimmentioning

confidence: 99%

“…Coronary sections can also be added to this structure if necessary. The hydromechanical properties of each section were reproduced as lumped parameter models, which comprised: resistive (R), capacitive (C) and/or inertial (L) elements [8,9]. To describe the general relationship in this circulatory network, Guyton et al's [10] and ship (EDPVR) [12] described the lling of the ventricle.…”

Section: Model Of the Cardiovascular Systemmentioning

confidence: 99%

Energetic parameter changes with mechanical ventilation in conjunction with BVAD assistance

Lazzari

Darowski

Ferrari

et al. 2002

Journal of Medical Engineering & Technology

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The aim was to assess the influence of a biventricular assist device (BVAD) on ventricular energetics parameters (external work, oxygen consumption, cardiac mechanical efficiency) for both ventricles, when mechanical ventilation was applied. The experiments were performed using a computer simulator of cardiovascular system (CARDIOSIM) after modelling a pathological state of the left ventricle (E(v)Left = 0. 9 mmHg cm(-3) and increasing pulmonary resistance (Rap = 0.3 mmHg cm(-3 s). The effect of mechanical ventilation was mean intrathoracic pressure changes from 0 to +5 mmHg. This simulation showed that application of BVAD for both ventricles reduces external work and that this effect is stressed by positive intrathoracic pressure, reduces cardiac mechanical efficiency that is quite insensitive to intrathoracic pressure and increases oxygen consumption, which is reduced by positive intrathoracic pressure. The increase of potential energy at the onset of BVAD evidences a rightwards shift of ventricular work cycle (unloading of the ventricles). In general, positive intrathoracic pressure during BVAD assistance adversely affects ventricular energetics.

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“…In the computer model the left and right heart, systemic arterial and venous section and also pulmonary arterial and venous section are represented. A modi ed rst-order windkessel model [13,16] reproduces the systemic and pulmonary arterial sections. Guyton [17], a variable elastance model was proposed which reproduces the ventricular pressure-volume relationships, with some modi cations for the ejection.…”

Section: Model Of Cardiovascular Systemmentioning

confidence: 99%

Ventricular energetics during mechanical ventilation and intraaortic balloon pumping?computer simulation

Lazzari

Darowski

Ferrari³

et al. 2001

Journal of Medical Engineering & Technology

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Computer simulation of a cardiovascular system enabled us to predict the effects of simultaneous application of mechanical ventilation (MV) and intraaortic ballon pumping (IABP) on ventricular energetics. External work (EW), pressure-volume area (PVA), potential energy (PE) and cardiac mechanical efficiency (CME) were calculated. Nummerical simulation showed that changes of positive intrathoracic pressure have a considerable effect on left and right ventricular EW, PE, PVA and CME, whether IABP is used or not. The right ventricular energetics was much less influenced by systemic resistance (Ras) changes than the left ventricular one. Simultaneous application of IABP and MV showed a remarkable effect on left ventricular EW. The net result was reversed sensitivity to pulmonary resistance (Rap) and reduced sensitivity to Ras. PVA was generally reduced, while CME is increased by simultaneous presence of IABP and MV. The sensitivity of CME to Rap and Ras variation was diminished in this situation.

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A desk-top computer model of the circulatory system for heart assistance simulation: effect of an LVAD on energetic relationships inside the left ventricle

Cited by 19 publications

References 6 publications

Numerical Simulation of Cardiovascular Dynamics With Left Heart Failure and In‐series Pulsatile Ventricular Assist Device

Numerical Simulation of Cardiovascular Dynamics With Left Heart Failure and In‐series Pulsatile Ventricular Assist Device

Energetic parameter changes with mechanical ventilation in conjunction with BVAD assistance

Ventricular energetics during mechanical ventilation and intraaortic balloon pumping?computer simulation

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