Left ventricular-arterial system coupling at peak exercise in dilated nonischemic cardiomyopathy

Cardiac Mechanical Performance Assessment at Different Levels of Exercise in Childhood Acute Lymphoblastic Leukemia Survivors

BACKGROUND

There is a shortage of relevant studies interested in cardiac mechanical performance. Thus, it is clinically relevant to study the impact of cancer treatments on survivors' cardiac mechanical performance to improve our knowledge. The first objective of this study is to assess survivors' cardiac mechanical performance during a cardiopulmonary exercise test (CPET) using both ventricular-arterial coupling (VAC) and cardiac work efficiency (CWE) from cardiac magnetic resonance (CMR) acquisitions. The second objective is to assess the impact of doxorubicin and dexrazoxane (DEX) treatments.

METHODS

A total of 63 childhood acute lymphoblastic leukemia survivors underwent a CMR at rest on a 3T magnetic resonance imaging system, followed by a CPET on ergocycle. The CircAdapt model was used to study cardiac mechanical performance. At different levels of exercise, arterial elastance, end-systolic elastance, VAC, and CWE were estimated.

RESULTS

We observed significant differences between the different levels of exercise for both VAC ( P <0.0001) and CWE parameters ( P =0.001). No significant differences were reported between prognostic risk groups at rest and during the CPET. Nevertheless, we observed that survivors in the SR group had a VAC value slightly lower than heart rate (HR)+DEX and HR groups throughout the CPET. Moreover, survivors in the SR group had a CWE parameter slightly higher than HR+DEX and HR groups throughout the CPET.

CONCLUSIONS

This study reveals that the combination of CPET, CMR acquisitions and CircAdapt model was sensitive enough to observe slight changes in the assessment of VAC and CWE parameters. Our study contributes to improving survivors' follow-up and detection of cardiac problems induced by doxorubicin-related cardiotoxicity.

Ventricular-Vascular Coupling at Rest and after Exercise Is Associated with Heart Failure Hospitalizations in Patients With Coronary Artery Disease

BACKGROUND

The ventricular-vascular coupling ratio, defined as the ratio of arterial elastance (E_a) to left ventricular end-systolic elastance (E_es), has not been examined in populations with coronary artery disease (CAD), and its association with heart failure (HF) in this population is unknown.

METHODS

Ventricular-vascular coupling was measured at rest and after exercise using echocardiography and cuff blood pressure in 815 patients with stable CAD enrolled in the Heart and Soul Study. Adjusted Cox proportional-hazard models were used to evaluate the association between ventricular-vascular coupling and future HF hospitalizations.

RESULTS

After a median of 8.9 years, 144 patients (18%) were hospitalized for HF. After multivariate adjustment, patients in the highest tertile of E_es (rest: hazard ratio [HR], 0.31 [95% CI, 0.17-0.57; P < .001]; exercise: HR, 0.26 [95% CI, 0.13-0.50; P < .001]) were at decreased risk for HF hospitalization, while patients in the highest tertile of the E_a/E_es ratio (rest: HR, 3.36 [95% CI, 1.91-5.93; P < .001]; exercise: HR, 4.09; [95% CI, 2.22-7.51; P < .001]) were at increased risk, compared with the lowest tertiles. E_a and the relative change observed in E_es and the E_a/E_es ratio with exercise were not associated with HF hospitalizations.

CONCLUSIONS

The E_a/E_es ratio and E_es, at rest and after exercise, are strongly associated with future HF hospitalizations in patients with stable CAD and low rates of baseline HF. Ventricular-vascular coupling obtained from echocardiography shows promise as a risk assessment tool for HF in patients with CAD.

Effects of exercise on postexercise ventricular-arterial coupling and pulsatile efficiency in patients with systolic dysfunction

BACKGROUND

A suboptimal ventricular-arterial (VA) interaction may have a prolonged depressing effect on the failing heart after functional reserves forced to their limits under stress conditions such as exercise. The continuation of excessive load in the postexercise period may be more important than the load during exercise, because the sum of postexercise periods generally exceeds exercise time itself. We sought that exercise-induced changes in postexercise VA coupling and pulsatile efficiency in patients with heart failure (HF).

METHODS

Thirty consecutive HF with reduced ejection fraction (EF) and thirty age-, sex- and peak VO2 -matched subjects with preserved EF were enrolled. Pre- and postexercise echocardiographic and tonometric measurements were taken to calculate left ventricular and arterial elastances, arterial compliance and wave reflections, and steady and pulsatile power.

RESULTS

VA coupling significantly deteriorated in HF group (from 1·50 ± 0·47 to 2·00 ± 0·75 mmHg/mL, P < 0·01), but control group maintained basal favourable coupling status after exercise (from 1·04 ± 0·29 to 1·03 ± 0·24 mmHg/mL, P = 0·77). Pulsatile percentage of total power significantly increased with exercise in HF group, whereas it showed a significant decrease in control group. The change in pulsatile power fraction was correlated with the change in augmentation pressure (r = 0·41, ß = 3·00, P < 0·01) and inversely correlated with the change in total arterial compliance (r = -0·29, ß = -8·52, P = 0·02).

CONCLUSION

Our data indicate that exercise-induced VA decoupling and pulsatile inefficiency extend into postexercise phase in patients with systolic dysfunction. The exact duration of these derangements requires further studies.

Changes in ventricular-arterial coupling during decongestive therapy in acute heart failure

AIMS

Coupled arterial and left ventricular properties are poorly documented in acute heart failure. The aim of this prospective noninvasive study was to document early changes in ventricular-arterial coupling in patients with acutely decompensated HF (ADHF).

METHODS AND RESULTS

We studied 19 patients hospitalized for ADHF (age 62 ± 15 years, NYHA class 3 or 4). Patients with shock and sustained arrhythmias were excluded. All the patients received intravenous loop diuretics, and none received intravenous vasodilators or inotropes. Ongoing chronic treatments were maintained. Echocardiography and radial artery tonometry were performed simultaneously on admission and after clinical improvement (day 4 ± 1 after admission). Classical echocardiographic parameters were measured, including stroke volume (SV). End-systolic pressure (Pes) was derived from reconstructed central aortic pressure, and arterial elastance (Ea) was calculated as Ea = Pes/SV. End-systolic LV elastance (Ees) was calculated with the single-beat method. Ventricular-arterial coupling was quantified as the Ea/Ees ratio. Following IV diuretic therapy, mean weight loss was 5 ± 2 kg (P < 0·01) and BNP fell from 1813 (median) (IQR = 1284-2342) to 694 (334-1053) pg/mL (P < 0·01). Ea fell by 29%, from 2·46 (2·05-2·86) to 1·78 (1·55-2·00) mmHg/mL (P < 0·01), while Ees remained unchanged (1·28 (1·05-1·52) to 1·13 (0·92-1·34) mmHg/mL). The Ea/Ees ratio therefore fell, from 2·13 (1·70-2·56) to 1·81 (1·56-2·08) (P < 0·02).

CONCLUSION

An early improvement in ventricular-arterial coupling was observed after diuretic-related decongestive therapy in ADHF patients and was related to a decrease in effective arterial elastance rather than to change in LV contractility.

Ventricular-arterial coupling, remodeling, and prognosis in chronic heart failure

OBJECTIVES

The objective of this study was to compare the physiological determinants of ejection fraction (EF)-ventricular size, contractile function, and ventricular-arterial (VA) interaction-and their associations with clinical outcomes in chronic heart failure (HF).

BACKGROUND

EF is a potent predictor of HF outcomes, but represents a complex summary measure that integrates several components including left ventricular size, contractile function, and VA coupling. The relative importance of each of these parameters in determining prognosis is unknown.

METHODS

In 466 participants with chronic systolic HF, we derived quantitative echocardiographic measures of EF: cardiac size (end-diastolic volume [EDV]); contractile function (the end-systolic pressure volume relationship slope [Eessb] and intercept [V0]); and VA coupling (arterial elastance [Ea]/Eessb). We determined the association between these parameters and the following adverse outcomes: 1) the combined endpoint of death, cardiac transplantation, or ventricular assist device (VAD) placement; and 2) cardiac hospitalization.

RESULTS

Over a median follow-up of 3.4 years, there were 76 deaths, 52 transplantations, 14 VAD placements, and 684 cardiac hospitalizations. EF was independently associated with death, transplantation, and VAD placement (adjusted hazard ratio [HR]: 3.0; 95% confidence interval [CI]: 1.8 to 5.0 comparing third and first tertiles), as were EDV (HR: 2.6; 95% CI: 1.5 to 4.2); V0 (HR: 3.6; 95% CI: 2.1 to 6.1); and Ea/Eessb (HR: 2.1; 95% CI: 1.3 to 3.3). EDV, V0, and Ea/Eessb were also associated with risk of cardiac hospitalization. Eessb was not significantly associated with any adverse outcomes in adjusted analyses.

CONCLUSIONS

Left ventricular size, V0, and VA coupling are associated with prognosis in systolic HF, but end-systolic elastance (Eessb) is not. Assessment of VA coupling via Ea/Eessb is an additional noninvasively derived metric that can be used to gauge prognosis in human HF.

The relationship between ventricular-vascular uncoupling during exercise and impaired left ventricular longitudinal functional reserve in hypertensive patients

Uncoupling between heart and vessel may be accompanied by left ventricular (LV) dysfunction during exercise. We investigated the association between ventricular-vascular uncoupling during exercise and impaired LV longitudinal functional reserve in hypertensive subjects. Supine bicycle exercise echocardiography (25-watt, 3-minute increments) was performed in 216 hypertensive patients (106 male; mean age, 58 ± 9 years). Arterial elastance (Ea), end-systolic ventricular elastance (Ees), and ventricular-vascular interaction (VVI) index (Ea/Ees) were calculated at rest and at each stage of exercise. The patients were divided into three groups according to the tertile value of VVI ratio. The VVI ratio was defined as the ratio of VVI index at 50 W exercise over VVI index at rest; normal VVI response (n = 72); borderline VVI response (n = 72); and abnormal VVI response (n = 72). There were no significant differences in conventional echo parameters, mitral inflow velocities, mitral annular early diastolic (E') velocity, and mitral annular systolic velocity (S') at rest among the three groups. However, E' velocities and S' velocities at 25 W and 50 W were significantly lower in patients with abnormal VVI response compared with those in the other groups (P = .010 at 25 W, P = .008 at 50 W in E' velocity; P = .022 at 25 W, P = .043 at 50 W in S' velocity). Longitudinal diastolic functional reserve index from rest to 50 W was significantly lower in patients with abnormal VVI response compared with the other groups. Ventricular-vascular uncoupling during exercise was related to impaired LV longitudinal functional reserve in hypertensive patients.

Arterial-ventricular coupling with aging and disease

Age is the dominant risk factor for cardiovascular diseases. Understanding the coupling between the left ventricle (LV) and arterial system, termed arterial-ventricular coupling (E(A)/E(LV)), provides important mechanistic insights into the complex cardiovascular system and its changes with aging in the absence and presence of disease. E(A)/E(LV) can be indexed by the ratio of effective arterial elastance (E(A); a measure of the net arterial load exerted on the LV) to left ventricular end-systolic elastance (E(LV); a load-independent measure of left ventricular chamber performance). Age-associated alterations in arterial structure and function, including diameter, wall thickness, wall stiffness, and endothelial dysfunction, contribute to a gradual increase in resting E(A) with age. Remarkably there is a corresponding increase in resting E(LV) with age, due to alterations to LV remodeling (loss in myocyte number, increased collagen) and function. These age-adaptations at rest likely occur, at least, in response to the age-associated increase in E(A) and ensure that E(A)/E(LV) is closely maintained within a narrow range, allowing for optimal energetic efficiency at the expense of mechanical efficacy. This optimal coupling at rest is also maintained when aging is accompanied by the presence of hypertension, and obesity, despite further increases in E(A) and E(LV) in these conditions. In contrast, in heart failure patients with either reduced or preserved ejection fraction, E(A)/E(LV) at rest is impaired. During dynamic exercise, E(A)/E(LV) decreases, due to an acute mismatch between the arterial and ventricular systems as E(LV) increases disproportionate compared to E(A) (≈200 vs. 40%), to ensure that sufficient cardiac performance is achieved to meet the increased energetic requirements of the body. However, with advancing age the reduction in E(A)/E(LV) during acute maximal exercise is blunted, due to a blunted increase E(LV). This impaired E(A)/E(LV) is further amplified in the presence of disease, and may explain, in part, the reduced cardiovascular functional capacity with age and disease. Thus, although increased stiffness of the arteries itself has important physiological and clinical relevance, such changes also have major implications on the heart, and vice versa, and the manner in the way they interact has important ramifications on cardiovascular function both at rest and during exercise. Examination of the alterations in arterial-ventricular coupling with aging and disease can yield mechanistic insights into the pathophysiology of these conditions and increase the effectiveness of current therapeutic interventions.

Aging-associated cardiovascular changes and their relationship to heart failure

Aging represents a convergence of declining cardioprotective systems and increasing disease processes that is fertile ground for the development of heart failure. Fifty percent of all heart failure diagnoses and 90% of all heart failure deaths occur in individuals older than 70. This article discusses the microscopic and macroscopic changes in cardiovascular structure, function, protective systems, and disease associated with aging. In addition to outlining important clinical considerations and conditions in older persons, the link between normal aging and the elevated risk for development of stage B heart failure is explained and potential therapeutic pathways are highlighted.

Use of the Frank-Starling mechanism during exercise is linked to exercise-induced changes in arterial load

Effective arterial elastance(E(A)) is a measure of the net arterial load imposed on the heart that integrates the effects of heart rate(HR), peripheral vascular resistance(PVR), and total arterial compliance(TAC) and is a modulator of cardiac performance. To what extent the change in E(A) during exercise impacts on cardiac performance and aerobic capacity is unknown. We examined E(A) and its relationship with cardiovascular performance in 352 healthy subjects. Subjects underwent rest and exercise gated scans to measure cardiac volumes and to derive E(A)[end-systolic pressure/stroke volume index(SV)], PVR[MAP/(SV*HR)], and TAC(SV/pulse pressure). E(A) varied with exercise intensity: the ΔE(A) between rest and peak exercise along with its determinants, differed among individuals and ranged from -44% to +149%, and was independent of age and sex. Individuals were separated into 3 groups based on their ΔE(A)I. Individuals with the largest increase in ΔE(A)(group 3;ΔE(A)≥0.98 mmHg.m(2)/ml) had the smallest reduction in PVR, the greatest reduction in TAC and a similar increase in HR vs. group 1(ΔE(A)<0.22 mmHg.m(2)/ml). Furthermore, group 3 had a reduction in end-diastolic volume, and a blunted increase in SV(80%), and cardiac output(27%), during exercise vs. group 1. Despite limitations in the Frank-Starling mechanism and cardiac function, peak aerobic capacity did not differ by group because arterial-venous oxygen difference was greater in group 3 vs. 1. Thus the change in arterial load during exercise has important effects on the Frank-Starling mechanism and cardiac performance but not on exercise capacity. These findings provide interesting insights into the dynamic cardiovascular alterations during exercise.

Arterial-ventricular coupling: mechanistic insights into cardiovascular performance at rest and during exercise

Understanding the performance of the left ventricle (LV) requires not only examining the properties of the LV itself, but also investigating the modulating effects of the arterial system on left ventricular performance. The interaction of the LV with the arterial system, termed arterial-ventricular coupling (E(A)/E(LV)), is a central determinant of cardiovascular performance and cardiac energetics. E(A)/E(LV) can be indexed by the ratio of effective arterial elastance (E(A); a measure of the net arterial load exerted on the left ventricle) to left ventricular end-systolic elastance (E(LV); a load-independent measure of left ventricular chamber performance). At rest, in healthy individuals, E(A)/E(LV) is maintained within a narrow range, which allows the cardiovascular system to optimize energetic efficiency at the expense of mechanical efficacy. During exercise, an acute mismatch between the arterial and ventricular systems occurs, due to a disproportionate increase in E(LV) (from an average of 4.3 to 13.2, and 4.7 to 15.5 mmHg.ml(-1).m(-2) in men and women, respectively) vs. E(A) (from an average of 2.3 to 3.2, and 2.3 to 2.9 mmHg.ml(-1).m(-2) in men and women, respectively), to ensure that sufficient cardiac performance is achieved to meet the increased energetic requirements of the body. As a result E(A)/E(LV) decreases from an average of 0.58 to 0.34, and 0.52 to 0.27 in men and women, respectively. In this review, we provide an overview of the concept of E(A)/E(LV), and examine the effects of age, hypertension, and heart failure on E(A)/E(LV) and its components (E(A) and E(LV)) in men and women. We discuss these effects both at rest and during exercise and highlight the mechanistic insights that can be derived from studying E(A)/E(LV).

Prognostic value of left-ventricular and peripheral vascular performance in patients with dilated cardiomyopathy

BACKGROUND

The goal of the heart during exercise is to increase cardiac output to metabolizing tissues. Our aim was to assess the relative role of systolic versus diastolic dysfunction in modulating cardiac output in patients with idiopathic left-ventricular (LV) dysfunction.

METHODS

We enrolled 51 patients (LV ejection fraction, mean +/- SD, = 36% +/- 9%) and 24 controls with a normal LV ejection fraction. All were scheduled for exercise radionuclide angiography for the evaluation of LV functional reserve, and were followed for a median of 129 months.

RESULTS

Stroke volume increased in control subjects mainly through a decrease in end-systolic volume, while it increased in patients through an increase in end-diastolic volume (EDV), albeit heterogeneously. Patients were divided into group I, with stroke volume increase, versus group II, without stroke volume increase, during stress. Despite similar blunted inotropic reserves, group I showed a decrease in arterial elastance during stress: a better ventricular-arterial coupling occurred, leading to increased cardiac efficiency. At long-term follow-up, the overall event-free survival was 88% in group I, compared with 61% for group II (log rank = 4.7, P = .03).

CONCLUSIONS

In the presence of idiopathic LV dysfunction, a preserved LV pumping reserve can be identified easily through stress-induced variations in the EDV and stroke volume, with a powerful, long-term death-risk stratification.

Central haemodynamics and peripheral muscle function during exercise in patients with chronic heart failure

In this narrative review of the current literature, we examine the central and peripheral mechanisms responsible for the exercise intolerance of chronic heart failure and highlight briefly the benefits of exercise training in the treatment of this debilitating disorder. Specifically, we identify the common finding of reduced cardiac output reserve during exercise conditions leading to decreased exercise tolerance. We also reveal that the stroke volume response to exercise varies depending on the individual patient, the presence of mitral regurgitation, and the aetiology of heart failure. Chronic heart failure patients with left ventricular systolic dysfunction appear able to use the Frank-Starling mechanism to compensate (in part) for their decreased contractile reserve. Patients with left ventricular diastolic dysfunction have normal contractile function; however, they are unable to make use of the Frank-Starling mechanism during exercise conditions. We also reveal that pericardial constraint may limit diastolic filling and exercise capacity in patients with chronic heart failure. It appears that interventions that reduce pericardial constraint and mitral regurgitation enhance diastolic filling and increase exercise tolerance. A series of peripheral muscle changes also occur, including changes in muscle mass, cellular structure, energy metabolism, and blood flow. Each of these factors is associated with decreased exercise capacity and the symptoms of chronic heart failure. Exercise training has been shown to improve both central haemodynamics and peripheral muscle function leading to improvements in exercise capacity, functional status, and overall quality of life in patients with chronic heart failure.

Ventriculovascular coupling in systolic and diastolic heart failure

Pressure-volume analysis has provided critical insight into ventricular mechanics, and it has elucidated the underlying mechanisms of heart failure (HF). Renewed interest in ventriculovascular coupling, the interaction of the left ventricle and the arterial system, has developed from recent investigations focusing on the importance of heart rate control in systolic HF, blood pressure lability in the elderly, and acute pulmonary edema in patients with HF and a normal ejection fraction. These data suggest that abnormal ventriculovascular coupling may be an additional pathophysiologic mechanism underlying the development of HF with a normal ejection fraction and may provide a target for novel therapies.

Ventriculovascular coupling in systolic and diastolic heart failure

Pressure-volume analysis has provided critical insight into ventricular mechanics, and it has elucidated the underlying mechanisms of heart failure (HF). Renewed interest in ventriculovascular coupling, the interaction of the left ventricle and the arterial system, has developed from recent investigations focusing on the importance of heart rate control in systolic HF, blood pressure lability in the elderly, and acute pulmonary edema in patients with HF and a normal ejection fraction. These data suggest that abnormal ventriculovascular coupling may be an additional pathophysiological mechanism underlying the development of HF with a normal ejection fraction and may provide a target for novel therapies.

Age and gender affect ventricular-vascular coupling during aerobic exercise

OBJECTIVES

The goal of this study was to examine the age-associated differences in ventricular-vascular coupling, defined by the ratio of arterial elastance (EaI) to left ventricular systolic elastance (E(LV)I), and its components, at rest and during exercise.

BACKGROUND

Ejection fraction (EF) increases during exercise, but the EF reserve decreases with aging. Ejection fraction is inversely related to EaI/E(LV)I, an index of the interaction between arterial and ventricular properties, which is an important determinant of cardiac performance. Thus, age differences in EaI/E(LV)I during exercise, due to age differences in EaI, E(LV)I, or both, may help to explain the age deficit in EF reserve.

METHODS

We noninvasively characterized EaI/E(LV)I = end-systolic volume index (ESVI)/stroke volume index (SVI) and its two determinants EaI = end-systolic pressure/SVI, and E(LV)I = end-systolic pressure/ESVI, at rest and during exercise in 239 healthy men and women (age range, 21 to 87 years). Blood pressures were assessed with cuff sphygomanometry, and cardiac volumes with gated blood pool scintingraphy.

RESULTS

Resting EaI/E(LV)I was not age related in men or women. In both sexes, EaI/E(LV)I decreased during exercise and declined to a lesser extent in older subjects. There were gender differences in the components of EaI/E(LV)I during exercise: EaI was greater in older versus young women (p = 0.01) but was unaffected by age in men. Left ventricular systolic elastance increased to a greater extent in young versus older subjects (p = 0.0001 for men, p = 0.07 for women).

CONCLUSIONS

Age-associated differences in EaI/E(LV)I occur in both genders during exercise. Sub-optimal ventricular-vascular coupling helps to explain the age-associated blunting of maximal exercise EF, and its underlying mechanisms appear to differ between men and women.

Aortic distensibility independently affects exercise tolerance in patients with dilated cardiomyopathy

BACKGROUND

Peak exercise oxygen consumption (VO2) is crucial for the prognostic stratification of patients with congestive heart failure, but its hemodynamic determinants are still not completely understood. Aortic wall elasticity modulates left ventricular function and coronary blood flow. Whether an increased aortic pulse-wave velocity (PWV), a known marker of arterial stiffness, may predict peak VO2 in patients with dilated cardiomyopathy (DCM) has to be clarified.

METHODS AND RESULTS

A total of 78 patients with clinical diagnosis of DCM (aged 62+/-11 years; female 29%; mean ejection fraction 34+/-9%) were selected. All patients underwent a complete echocardiographic-Doppler evaluation. Aortic PWV was measured by Doppler ultrasonography immediately before the exercise. A bicycle exercise test with expiratory gas exchange monitoring was performed to determine VO2 . Plasma concentration of the amino-terminal propeptide of type III procollagen (PIIINP), a marker of extracellular matrix turnover, was determined. Mean PWV was 5.7+/-2.2 m/s, and VO2 was 16.5+/-4.5 mL x kg(-1) x min(-1). The hemodynamic variables correlated with VO2 were PWV (r=-0.39, P=0.0007) and stroke volume (r=0.38, P=0.002). In a multivariate analysis, PWV (P=0.04) and stroke volume (P=0.05) were independently correlated with VO2 , accounting for 34% of its variance. PIIINP levels correlated with PWV (r=0.35, P=0.002) and a more restrictive diastolic filling pattern (r=0.40, P=0.02).

CONCLUSIONS

Increased aortic stiffness measured by PWV is an independent predictor of peak VO2 and could partially explain exercise intolerance in patients with DCM.

Pathological patient in protocol definition for bench testing of mechanical cardiac support system

Clinical techniques for the restoration of a failing heart are mainly based on the use of mechanical assist devices. In recent years, with the growing need for mechanical circulatory support, these devices have been shown to be a useful therapeutic tool, thanks to their intrinsic capability to unload the failing ventricle, allowing the heart to recover. Mechanical circulatory support systems (MCSS) require an accurate biomechanical characterization of the complex interaction that occurs between the patient and the mechanical support. A protocol for MCSS testing is proposed which takes into account several working conditions, in a modified test mock loop apparatus able to mimic various pathological conditions. Both physiological and pathological conditions can be replicated to show the actual efficacy of a MCSS device in correctly supporting a wide spectrum of ventricular conditions. The test bench is able to simulate the recovery of the pathological condition quite accurately, showing, at the same time, that this set up can be a reliable choice to characterize cardiac support devices. Thus the results of this experimentation can be useful to clinicians in forecasting the response of the heart affected by a cardiac disease and to set appropriate parameters for suitable assistance.