Windkessel Model Research Articles

Biomechanical model of bile flow in the biliary system

The biliary system function is to transport bile into the duodenum for the fat digestion. Metabolic disorders and choledynamics disturbances may cause the cholelithiasis. In Russia, the pathology of the biliary system ranks third in the patients number. The surgical treatment of cholelithiasis is the gallbladder removal (cholecystectomy). However, the percentage of postoperative complications is quite high. One of the reasons is the lack of objective methods: surgeons are not always able to evaluate the surgical intervention consequences. Nevertheless, there are very few works devoted to the numerical simulation of processes associated to a bile flow. There was no complete personalized model that could be used in medical practice to the date. This paper presents a new model of the bile flow in the biliary system. The proposed approach is that the biliary system is considered as a combination of the three parts (the gallbladder, extrahepatic bile ducts, and the major duodenal papilla). The Windkessel model was used to simulate the bile flow in the gallbladder. The bile flow in the extrahepatic bile ducts can be considered as a fluid–structure interaction flow. The bile flow in the major duodenal papilla was considered as a peristaltic transport in a finite-length tapered tube. A complex model of the biliary system allowed us to evaluate choledynamics in the healthy state, at pathology, as well as to carry out a numerical assessment of the bile flow after cholecystectomy to predict and prevent complications. The utilization of peristaltic flow modelling in the major duodenal papilla allowed us to determine the quantitative criteria for the occurrence of pathological reflux, which made it possible to ensure its prevention. The model can also be used to analyze surgical interventions in the treatment of cholelithiasis and its complications (stenting, anterior abdominal wall suturing). For example, the mathematical model of the installation of a stent with shape memory reduces the number of complications (soft tissue perforation). The numerical model of the accumulation of particles on the surface of the plastic stent made it possible to predict the replacement period for a particular patient and to improve the quality of his life. The biomechanical analysis of the use of suture materials allowed us to provide a differentiated approach to suture materials and to reduce the number of specific postoperative complications. It is shown that the developed model can be used to create a software to support decision-making when performing cholelithiasis treatment to prevent complications.

Anatomically based simulation of hepatic perfusion in the human liver.

Liver structures of a healthy subject are digitised and segmented from computed tomography (CT) images, and hepatic perfusion is modelled in the hepatic artery and portal vein of the healthy subject with structured tree-based outflow boundary conditions. This self-similar structured tree is widely used in the literature, eg, blood flow simulation in larger systemic arteries and cerebral circulation, and is used in this study to model the effect of the smaller hepatic arteries and arterioles, as well as the smaller hepatic portal veins and portal venules. Physiologically reasonable results are obtained. Since the structured tree terminates at the size of the microvasculature system in liver lobules, the structured tree boundary condition will enable the proposed organ-level model of hepatic arterial flow to be easily connected to tissue-level models of liver lobules. Blood flow in the hepatic vein is also modelled in this subject with three-element Windkessel model as outflow boundary conditions. The benefit of integrating the perfusion in all hepatic vascular vessels is that it helps us analyse some complicated clinical phenomenon more efficiently, eg, one possible application is to obtain the portal pressure gradient (PPG) to help examine the reliability of hepatic venous pressure gradient (HVPG) as an indirect measure of portal pressure. Moreover, since four to six generations of hepatic vessels, which are sufficient for liver classification analysis, were employed in the model, this study is setting the computational foundation of a potentially handy surgical tool.

A Primary Computational Fluid Dynamics Study of Pre- and Post-TEVAR With Intentional Left Subclavian Artery Coverage in a Type B Aortic Dissection.

The impact of left subclavian artery (LSA) coverage during thoracic endovascular aortic repair (TEVAR) on the circulatory system is not fully understood. Here, we coupled a single-phase non-Newtonian model with fluid-structure interaction (FSI) technique to simulate blood flow in an acute type B aortic dissection. Three-element Windkessel model was implemented to reproduce physiological pressure waves, where a new workflow was designed to determine model parameters with the absence of measured data. Simulations were carried out in three geometric models to demonstrate the consequence of TEVAR with the LSA coverage; case A: pre-TEVAR aorta; case B: post-TEVAR aorta with the disappearance of LSA; case C: post-TEVAR aorta with virtually adding LSA. Results show that the blood flow through the compressed true lumen is only 8.43%, which may lead to ischemia in related organs. After TEVAR, the wall pressure on the stented segment increases and blood flow in the supra-aortic branches and true lumen is improved. Meantime, the average deformation of the aorta is obviously reduced due to the implantation of the stent graft. After virtually adding LSA, significant changes in the distribution of blood flow and two indices based on wall shear stress are observed. Moreover, the movement of residual false lumen becomes stable, which could contribute to patient recovery. Overall, this study quantitatively evaluates the efficacy of TEVAR for acute type B aortic dissection and demonstrates that the coverage of LSA has a considerable impact on the important hemodynamic parameters.

Large vessels as a tree of transmission lines incorporated in the CircAdapt whole-heart model: A computational tool to examine heart-vessel interaction.

We developed a whole-circulation computational model by integrating a transmission line (TL) model describing vascular wave transmission into the established CircAdapt platform of whole-heart mechanics. In the present paper, we verify the numerical framework of our TL model by benchmark comparison to a previously validated pulse wave propagation (PWP) model. Additionally, we showcase the integrated CircAdapt–TL model, which now includes the heart as well as extensive arterial and venous trees with terminal impedances. We present CircAdapt–TL haemodynamics simulations of: 1) a systemic normotensive situation and 2) a systemic hypertensive situation. In the TL–PWP benchmark comparison we found good agreement regarding pressure and flow waveforms (relative errors ≤ 2.9% for pressure, and ≤ 5.6% for flow). CircAdapt–TL simulations reproduced the typically observed haemodynamic changes with hypertension, expressed by increases in mean and pulsatile blood pressures, and increased arterial pulse wave velocity. We observed a change in the timing of pressure augmentation (defined as a late-systolic boost in aortic pressure) from occurring after time of peak systolic pressure in the normotensive situation, to occurring prior to time of peak pressure in the hypertensive situation. The pressure augmentation could not be observed when the systemic circulation was lumped into a (non-linear) three-element windkessel model, instead of using our TL model. Wave intensity analysis at the carotid artery indicated earlier arrival of reflected waves with hypertension as compared to normotension, in good qualitative agreement with findings in patients. In conclusion, we successfully embedded a TL model as a vascular module into the CircAdapt platform. The integrated CircAdapt–TL model allows detailed studies on mechanistic studies on heart-vessel interaction.

Windkessel Measures Derived From Pressure Waveforms Only: The Framingham Heart Study.

BackgroundWaveform parameters derived from pressure‐only Windkessel models are related to cardiovascular disease risk and could be useful for understanding arterial system function. However, prior reports varied in their adjustment for potential confounders.Methods and ResultsCarotid tonometry waveform data from 2539 participants (mean age 63±11 years, 58% women) of the Framingham Heart Study were used to derive Windkessel measures using pressure and assuming a linear model with fixed diastolic time constant (τdias) and variable asymptotic pressure (Pinf, median 54.5; 25th, 75th percentiles: 38.4, 64.9 mm Hg) or nonlinear model with inverse pressure‐dependent τdias and fixed Pinf (20 mm Hg). During follow‐up (median 15.1 years), 459 (18%) participants had a first cardiovascular disease event. In proportional hazards models adjusted for age, sex, total cholesterol, high‐density lipoprotein cholesterol, smoking, antihypertensive medication use, diabetes mellitus, and physician‐acquired systolic blood pressure, only the systolic time constant (τsys) derived from the nonlinear model was related to risk for cardiovascular disease events (hazard ratio=0.91 per 1 SD, 95% CI=0.84–0.99, P=0.04). When heart rate was added to the model, τsys (hazard ratio=0.92, CI=0.84–1.00, P=0.04) and reservoir pressure amplitude (hazard ratio=1.14, CI=1.01–1.28, P=0.04) were related to events. In contrast, measures derived from the linear model were not related to events in models that adjusted for risk factors including systolic blood pressure (P>0.31) and heart rate (P>0.19).ConclusionsOur results suggest that pressure‐only Windkessel measures derived by using a nonlinear model may provide incremental risk stratification, although associations were modest and further validation is required.

Two-Element Fractional-Order Windkessel Model to Assess the Arterial Input Impedance.

Arterial system is completely coupled with the heart, such that the contractile state of the left ventricle and its produced central blood pressure (the pressure in the aorta) are in tune with the arterial mechanical properties. This study investigates the use of fractional-order capacitor and resistor elements to expose, and estimate the main arterial mechanical properties. We propose a simple two-element fractional-order Windkessel model that is able to capture the real aortic impedance dynamic for different cardiac physiological states. To perform a quantitative validation, in-silico ascending aortic blood pressure and flow database of 3,325 virtual subjects was used. The proposed model provides new simplified tool for "hemodynamic problem" solving, offering a pioneer way for a better understanding of vascular mechanical properties dependency on hemodynamic changes such as arterial viscoelasticity.

Modeling fMRI BOLD signals and temporal mismatches in the cerebellar cortex

To understand brain activity relating neurons to circuits to learning and behavior, we explored a bottom-up computational reconstruction of population signals arising from cerebellum granular layer. As a first implementation, using bio-realistic computational models of cerebellum granule cell, in vivo spike train patterns were computed and then translated into functional Magnetic Resonance Imaging, Blood Oxygen-Level Dependent (BOLD) signals. The BOLD response was generated from averaged activity arising from center-surround organization modeled by using excitatory-inhibitory ratios related to experimental data. The averaged responses were converted to BOLD signals using the balloon and modified Windkessel models. Although both models generated BOLD responses corresponding to neural activity, the temporal mismatch was attributed to the response by the delayed compliance parameter in the Windkessel model. The modeling suggests that experimental variability observed in the cerebellar micro-zones could be related to compliance chances, activation patterns and number of neurons. Although detailed neuro-vasculature information was not modeled, the advantage in this methodology is that cerebellar cortex may allow seemingly linear transformations of underlying spiking that could be then used to validate network reconstructions.

Determination of cardiac output from pulse pressure contour during intra-aortic balloon pumping in patients with low ejection fraction

Evaluation of a new Windkessel model based pulse contour method (WKflow) to calculate stroke volume in patients undergoing intra-aortic balloon pumping (IABP). Preload changes were induced by vena cava occlusions (VCO) in twelve patients undergoing cardiac surgery to vary stroke volume (SV), which was measured by left ventricular conductance volume method (SVlv) and WKflow (SVwf). Twelve VCO series were carried out during IABP assist at a 1:2 ratio and seven VCO series were performed with IABP switched off. Additionally, SVwf was evaluated during nine episodes of severe arrhythmia. VCO’s produced marked changes in SV over 10–20 beats. 198 paired data sets of SVlv and SVwf were obtained. Bland–Altman analysis for the difference between SVlv and SVwf during IABP in 1:2 mode showed a bias (accuracy) of 1.04 ± 3.99 ml, precision 10.9% and limits of agreement (LOA) of − 6.94 to 9.02 ml. Without IABP bias was 0.48 ± 4.36 ml, precision 11.6% and LOA of − 8.24 to 9.20 ml. After one thermodilution calibration of SVwf per patient, during IABP the accuracy improved to 0.14 ± 3.07 ml, precision to 8.3% and LOA to − 6.00 to + 6.28 ml. Without IABP the accuracy improved to 0.01 ± 2.71 ml, precision to 7.5% and LOA to − 5.41 to + 5.43 ml. Changes in SVlv and SVwf were directionally concordant in response to VCO’s and during severe arrhythmia. (R2 = 0.868). The SVwf and SVlv methods are interchangeable with respect to measuring absolute stroke volume as well as tracking changes in stroke volume. The precision of the non-calibrated WKflow method is about 10% which improved to 7.5% after one calibration per patient.

Observer-Based Monitoring of the Cardiovascular System

An observer-based state and fault estimation method for the cardiovascular system is presented in this brief. The approach is based on the use of a four-element windkessel model which is written in a singular state-space form. This particular representation allows to design an observer to estimate the systemic pressure, the aortic blood flow, and possible problems in the flow through the aorta for monitoring purposes. Numerical simulations are performed in order to demonstrate the pertinence of this representation to conceive an adequate observer to monitor the cardiovascular activity.

A novel porous media-based approach to outflow boundary resistances of 1D arterial blood flow models

In this paper we introduce a novel method for prescribing terminal boundary conditions in one-dimensional arterial flow networks. This is carried out by coupling the terminal arterial vessel with a poro-elastic tube, representing the flow resistance offered by microcirculation. The performance of the proposed porous media-based model has been investigated through several different numerical examples. First, we investigate model parameters that have a profound influence on the flow and pressure distributions of the system. The simulation results have been compared against the waveforms generated by three elements (RCR) Windkessel model. The proposed model is also integrated into a realistic arterial tree, and the results obtained have been compared against experimental data at different locations of the network. The accuracy and simplicity of the proposed model demonstrates that it can be an excellent alternative for the existing models.

Numerical simulation of two-phase non-Newtonian blood flow with fluid-structure interaction in aortic dissection

The behavior of blood cells and vessel compliance significantly influence hemodynamic parameters, which are closely related to the development of aortic dissection. Here the two-phase non-Newtonian model and the fluid-structure interaction (FSI) method are coupled to simulate blood flow in a patient-specific dissected aorta. Moreover, three-element Windkessel model is applied to reproduce physiological pressure waves. Important hemodynamic indicators, such as the spatial distribution of red blood cells (RBCs) and vessel wall displacement, which greatly influence the hemodynamic characteristics are analyzed. Results show that the proximal false lumen near the entry tear appears to be a vortex zone with a relatively lower volume fraction of RBCs, a low time-averaged wall shear stress (TAWSS) and a high oscillatory shear index (OSI), providing a suitable physical environment for the formation of atherosclerosis. The highest TAWSS is located in the narrow area of the distal true lumen which might cause further dilation. TAWSS distributions in the FSI model and the rigid wall model show similar trend, while there is a significant difference for the OSI distributions. We suggest that an integrated model is essential to simulate blood flow in a more realistic physiological environment with the ultimate aim of guiding clinical treatment.

Arteriyal Kan Basınç Sinyallerinin Elektriksel Analojisi

In this study, we propose an electrical circuit model that will be useful for understanding of the mechanisms and dynamics of the human cardiovascular system, which is considered as a complex system in the field of physiology. The electrical circuit model, defined as the Windkessel model, plays an important role in the observation of the characteristic effect of the blood pressure on the arterial system. An electrical circuit model, which we have connected to the input terminals of the Windkessel model, ensures that the mean arterial blood pressure signals are observed within the expected range of values. The Windkessel circuit model that we have tried to develop in this study was constructed in a laboratory environment and the results were observed. It is thought that this study will contribute to the literature in terms of the development of the Windkessel model by increasing the number of parameters involved in the models of heart and arterial system.

Modelling of the carotid artery

This study presents a modelling for the carotid artery that allows to analyze the theoretical behavior of pressure, flow and arterial volume in it, from the variation of both physical and physiological characteristics, such as: the thickness and length of the vessel blood, the viscosity and density of blood; determinants in the study of the normal functionality of the artery. The model of the arterial vessel –an adaptation of the Windkessel model of three elements, reported by Westerhof and Stergiopulos–, consists of an electrical circuit composed of passive RLC elements. The arterial segment was analyzed by mathematical and computational tools, relating Poiseuille's laws and electric laws. The pressure, flow and volume curves were obtained when changes occurred in the measurable characteristics of the carotid artery, in order to facilitate the medical interpretation of possible pathologies related to these changes.

A Low-Cost Tonometer Alternative: A Comparison Between Photoplethysmogram and Finger Ballistocardiogram and Validation Against Tonometric Waveform

Hypertension is a silent killer and one-third of its sufferers are unaware of its presence. Tonometric devices, like SphygmoCor, Compilor etc., represent the gold standard in pulse wave velocity (PWV) and augmentation index (AIx) measurements which are limited by their high cost and operational accuracy. Here, we present an alternative technology that is low cost and may be suitable for the `wearable' setting. We undertook the comparisons of arterial waveforms obtained by photoplethysmogram (PPG) and finger ballistocardiogram (BPP) sensors which were then validated against a SphygmoCor tonometric device. Specifically, the agreement analysis of the augmentation, stiffness, reflection, elasticity, ejection elasticity and dicrotic reflection indexes showed that arterial distension waveform sensing using BPP sensor, has precision and accuracy similar to that of a SphygmoCor tonometric device whilst outperforming the volumetric arterial flow sensing using a PPG sensor, in every index. BPP indexes showed the r 2 fit of up to 0.95 and Spearman's rank correlation up to 0.91 when validated against the SphygmoCor tonometer. The estimated individual transfer functions for the BPP sensor, with reference to SphygmoCor, have accuracies of above 85% and 98% for 2 and 4-element windkessel (WK) models, respectively. The findings reported in this work may also be useful for the development of systems that are beneficial in the early and/or routine detection of hypertension.

A hybrid Windkessel-Womersley model for blood flow in arteries

A hybrid Windkessel-Womersley (WK-W) coupled mathematical model for the study of pulsatile blood flow in the arterial system is proposed in this article. The model consists of the Windkessel-type proximal and distal compartments connected by a tube to represent the aorta. The blood flow in the aorta is described by the Womersley solution of the simplified Navier-Stokes equations. In addition, we defined a 6-elements Windkessel model (WK6) in which the blood flow in the connecting tube is modeled by the one-dimensional unsteady Bernoulli equation. Both models have been applied and validated using several aortic pressure and flow rate data acquired from different species such as, humans, dogs and pigs. The results have shown that, both models were able to accurately reconstruct arterial input impedance, however, only the WK-W model was able to calculate the radial distribution of the axial velocity in the aorta and consequently the model predicts the time-varying wall shear stress, and frictional pressure drop during the cardiac cycle more accurately. Additionally, the hybrid WK-W model has the capability to predict the pulsed wave velocity, which is also not possible to obtain when using the classical Windkessel models. Moreover, the values of WK-W model parameters have found to fall in the physiologically realistic range of values, therefore it seems that this hybrid model shows a great potential to be used in clinical practice, as well as in the basic cardiovascular mechanics research.

Whole-body vs. regional arterial stiffness: implications for a single Windkessel model of the circulation

IntroductionWe questioned whether a single Windkessel (WK) adequately describes the circulation by estimating the radial arterial diastolic pressure-decay constant (tau) and combining this with systemic hemodynamic and arterial stiffness measurements.MethodsIn the non-invasive cardiac laboratory, we performed echocardiography with simultaneous cuff BP, heart-femoral [hf] and femoral-ankle [fa] PWV (Colin VP1000), and radial tonometry (Sphygmocor). Tau was calculated by photo-digitizing the radial pulse contour and fitting pressures (at 20 ms intervals) to: P = A + ([systolic BP]-A)*exp(-(t-t0)/tau), where P = pressure, A = modeled minimum diastolic BP, and t0 = mono-exponential decay start time. Systemic vascular resistance (SVR) = mean pressure/[cardiac output]; WK stiffness (1/[WK capacitance]) = SVR/tau; central and peripheral arterial stiffness = hfPWV 2 and faPWV 2 , respectively; and estimated wall/ lumen ratio (W/L) = PWV 2/(central pulse pressure/stroke volume).ResultsIn 76 individuals (mean age 55 years, weight 84 kg, BP 138/79 mmHg, resting HR 67; 45% female), WK stiffness was negatively correlated with age(p<0.05) but not with BP, hfPWV2 or faPWV2. In contrast, hfPWV2and faPWV2 were positively correlated with age (p<0.0001 and p<0.01, respectively) but neither was correlated with tau or WK stiffness. Using 6 multilinear stepwise backward regression models for WK stiffness, the major contributing factors were: SVR (p<10−6), t0 (p<10−6), heart rate (p<10−5), and W/L (p=0.01).ConclusionWe identified SVR, heart rate, timing of pressure decay, and vessel geometry as correlates of WK stiffness but the lack of relationship between PWV-based arterial stiffness and stiffness derived from the WK model mitigates against a single arterial WK.

The pulsatile component of left atrial pressure has little effect on pulmonary artery impedance estimation in normal rats.

Pulmonary artery impedance (PAZ) that measures the pulsatile properties of the vasculature provides diagnostic and prognostic information in patients with pulmonary vascular diseases. While downstream pressure [i.e., left atrial (LA) pressure] should be considered when calculating static properties of pulmonary vasculature, PAZ is commonly estimated without taking into account the pulsatile component of LA pressure. We examined whether PAZ can be estimated with reasonable accuracy without using LA pressure. Pulmonary artery (PA) flow, PA pressure, and LA pressure were measured under irregular pacing in eight normal Sprague‐Dawley rats. PAZ was estimated by analyzing a one‐input, one‐output system (I1O1 analysis) that does not include LA pressure, and a two‐input, one‐output system (I2O1 analysis) that includes LA pressure. Using a tube and 3‐element Windkessel model, PAZ was parameterized as peripheral resistance (RP), arterial compliance (CP), characteristic impedance (ZC), and transmission time to the reflection site (TD). These parameters were not significantly different between the I1O1 and I2O1 analyses (RP: 0.286 ± 0.040 vs. 0.274 ± 0.038 mmHg·min/mL, CP: 0.352 ± 0.049 vs. 0.343 ± 0.041 mL/mmHg, ZC: 0.115 ± 0.005 vs. 0.117 ± 0.005 mmHg·min/mL, TD: 13.2 ± 1.8 vs. 12.9 ± 1.7 msec). In conclusion, the I1O1 analysis that does not use LA pressure estimates PAZ with reasonable accuracy compared with the I2O1 analysis that uses LA pressure in normal rats. Our finding that the pulsatile component of LA pressure contributes little to PAZ estimation may justify the clinical use of the I1O1 analysis.

Altered Placental Chorionic Arterial Biomechanical Properties During Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR) is a pregnancy complication due to placental dysfunction that prevents the fetus from obtaining enough oxygen and nutrients, leading to serious mortality and morbidity risks. There is no treatment for IUGR despite having a prevalence of 3% in developed countries, giving rise to an urgency to improve our understanding of the disease. Applying biomechanics investigation on IUGR placental tissues can give important new insights. We performed pressure-diameter mechanical testing of placental chorionic arteries and found that in severe IUGR cases (RI > 90th centile) but not in IUGR cases (RI < 90th centile), vascular distensibility was significantly increased from normal. Constitutive modeling demonstrated that a simplified Fung-type hyperelastic model was able to describe the mechanical properties well, and histology showed that severe IUGR had the lowest collagen to elastin ratio. To demonstrate that the increased distensibility in the severe IUGR group was related to their elevated umbilical resistance and pulsatility indices, we modelled the placental circulation using a Windkessel model, and demonstrated that vascular compliance (and not just vascular resistance) directly affected blood flow pulsatility, suggesting that it is an important parameter for the disease. Our study showed that biomechanics study on placenta could extend our understanding on placenta physiology.

A 0D representation of the arterial network incorporating the heart

Since Otto Frank first introduced the Windkessel (0D) model in 1899 to reproduce the arterial network, various versions were constructed which differ through their number of elements and their disposal. The purpose of this paper is to couple the left heart model given by M. Danielsen and J.T. Ottesen to a classic three-element 0D representation of the arterial network and compare the results with the output of a 13-elements arterial model coupled with the heart. This is done in order to proof that no great benefit is gained when increasing the number of elements of the Windkessel model if the input satisfies normal physiological conditions. After confirming that the model works properly, a simulation is performed with parameters specific for a hypertensive person. The output is assessed against results specific for a normal person and the differences are further analysed.

RF40 LEFT VENTRICULAR UNLOADING DURING ECMO: ATRIAL SEPTAL DEFECT VS IMPELLA. A SIMULATION STUDY

Aim: VA ECMO causes increase of LV afterload. Realization of ASD or Implantation of Impella have been proposed for LV unloading in combination with VA ECMO. Our aim is to study haemodynamic changes in VA ECMO patients after Impella or ASD realization using numerical model of cardiovascular system. Methods: A previously developed lumped parameter model of human cardiovascular system was adopted to this specific study. Heart chambers are represented by variable elastance models, while peripheral sections are represented by windkessel models. ASD was modelled as resistance separating the two atria. VA ECMO and Impella were modelled starting from their pressure-flow characteristics. Baseline condition of patient undergoing VA ECMO implantation was reproduced starting form haemodynamic and echocardiographic data and then the effect of different size ASD or different Impella support were simulated. Results: Impella implantation on VA ECMO patient caused an increment of mean arterial pressure up to 67%, a decrement in mean pulmonary pressure up to 8%, a decrement in LV end systolic volume up to 11% with reduction up to 97% of LV cardiac output. The realization of a calibrated ASD reduces the LA pressure up to 19%, increases right atrial pressure up to 22%, increases the MAP up to 18%, decreases the LVESV up to 11%, increase the RV volume up to 33% and decreases the LVCO up to 55%. Conclusion: Simulations results showed a higher capability of Impella in LV unloading during VA ECMO in comparison to ASD with a concomitant lower right ventricular overload.