Emergency implantation of a left ventricular assist device in adolescents with biventricular failure

Adolescents with congestive cardiomyopathy who present with intractable arrhythmia or progressive ventricular failure have a very poor prognosis and often die awaiting cardiac transplantation (CTx). We present our recent experience with a pneumatically powered left ventricular assist device (LVAD) implanted emergently to salvage adolescents with severe biventricular failure. Four patients, aged 15-17 years, body surface areas of 1.5-1.7 m2, with dilated cardiomyopathy (LV diastolic dimension, 7.1-8.3 cm); two presented with cardiovascular collapse, one with refractory ventricular tachycardia, and one with cardiac arrest. Hemodynamic and biochemical data before and 1 week after LVAD placement are expressed as mean and range values. None of the patients required right ventricular assist, and all patients achieved functional recovery while on LVAD support (8-71 days). Currently, all four patients are alive (11-22 months) after successful CTx. We conclude that emergency implantation of an LVAD in adolescents with biventricular heart failure can be life saving. As has been shown in the adult population, such a ventricular assist system restores normal circulatory hemodynamics, reverses multi-organ dysfunction, and provides a "safe" bridge to transplantation.     

Biventricular support with the Jarvik 2000 ventricular assist device in a calf model of pulmonary hypertension

The Jarvik 2000 ventricular assist device (VAD) is clinically efficacious for treating end-stage left ventricular failure. Because simultaneous right ventricular support is also occasionally necessary, we developed a biventricular Jarvik 2000 technique and tested it in a calf model. One VAD was implanted in the left ventricle with outflow-graft anastomosis to the descending aorta. The other VAD was implanted in the right ventricle with outflow-graft anastomosis to the pulmonary artery. Throughout the 30 day study, hemodynamic values were continuously monitored. On day 30, both pumps were evaluated at different speeds, under various hemodynamic conditions. By gradually occluding the pulmonary artery proximally or distally, we simulated varying degrees of high pulmonary vascular resistance, right ventricular hypertension, global heart failure, or ventricular fibrillation. The two VADs maintained biventricular support even during pulmonary artery occlusion and ventricular fibrillation, yielding a cardiac output of 3-11 L/min, left ventricular end-diastolic pressure of 11-24 mm Hg, and central venous pressure of 9-25 mm Hg. End-organ function was unimpaired, and no major adverse events occurred. The dual VADs offered safe, effective biventricular assistance in the calf. Additional studies are needed to assess the effects of lowered pulse pressure upon the pulmonary circulation and to develop a single pump speed controller.     

Successful bridge to resynchronization therapy with a left ventricular assist system in a patient with idiopathic dilated cardiomyopathy

Implantation of a left ventricular assist system (LVAS) in patients with idiopathic dilated cardiomyopathy (DCM) may improve cardiac function and allow explantation of the device. Generally, an ejection fraction of more than 40% is considered necessary for successful weaning from an LVAS, but less than 10% of DCM patients with an LVAS can achieve such a significant recovery of cardiac function. Cardiac resynchronization therapy, or atrial-synchronized biventricular pacing, has been found to treat congestive heart failure and ventricular dyssynchrony effectively. Here we report on a patient with an LVAS, in whom enough functional recovery could be obtained with resynchronization therapy for the device to be explanted successfully. A 32-year-old man was implanted with a Toyobo-NCVC paracorporeal LVAS to treat his intractable heart failure caused by idiopathic dilated cardiomyopathy. While on the LVAS for 8 months, his cardiac function recovered to some extent. The ejection fraction of his left ventricle (LVEF) improved from 9% to 41%. He chose explantation of the device rather than heart transplantation. Because he occasionally showed a wide QRS pattern on his ECG, epicardial biventricular pacing leads as well as a biventricular pacemaker were implanted on LVAS explantation surgery. An echocardiogram 2 weeks after explantation showed a marked difference in his LVEF by switching his biventricular pacing on and off (40% with biventricular pacing on and 29% with it off). Biventricular pacing may help recovery of cardiac function in selected LVAS patients and contribute to the increase in bridge to recovery cases.     

Triple-site pacing: a new supported therapy approach for bridge to recovery with a left ventricular assist system in a patient with idiopathic dilated cardiomyopathy

Left ventricular assist devices (LVAD) are widely used as bridges to cardiac transplantation or for destination therapy. LVAD support may also function as a bridge to ventricular recovery, but a sufficient rate of recovery has not been obtained, even with various adjuvant therapies. Cardiac resynchronization therapy (CRT) is an effective treatment for heart failure, and there is a report of successful weaning off LVAD with CRT. However, some patients with CRT could not improve their cardiac function because of residual dyssynchrony. Herein, we describe a case of a successful bridge to recovery with triple-site pacing for residual dyssynchrony after biventricular pacing. A 34-year-old woman with heart failure due to dilated cardiomyopathy whose condition deteriorated underwent Toyobo LVAD implantation, resulting in improvement of the left ventricular ejection fraction (LVEF) from 12 to 36%. Because of left ventricular dyssynchrony, we performed CRT, but residual dyssynchrony impeded cardiac recovery. We inserted an additional ventricular lead at the right ventricular outlet to achieve triple-site pacing in order to obtain complete synchronization. The LVEF improved to 45%, and the patient was successfully weaned off the LVAD. In LVAD-supported cases of persistent left ventricular dyssynchrony with CRT, implantation of triple-site pacing could potentially accelerate recovery.     

双心室辅助对缺血性左右心功能不全血流动力学影响的实验研究

比较在缺血性左右心功能不全时左心辅助和双心室辅助对血流动力学的不同影响 ,为自制气动隔膜泵(罗叶泵 )的临床应用提供实验依据。采用 8只健康成年犬 ,植入左心辅助装置和右心辅助装置。结扎左前降支 ,3mins后在窦房结支发出处远侧端结扎右冠状动脉 ,以建立缺血性左右心功能不全的动物模型。先行左心辅助 5mins,再行双心室辅助。分别记录中心静脉压 ,心输出量 ,平均动脉压 ,肺动脉压 ,肺毛细血管楔压等血流动力学指标。结果表明 :双心室辅助时心输出量显著上升 (0 .82 2± 0 .0 9L / min vs 1.33± 0 .12 L / m in,P<0 .0 1)与正常对照值相比无显著差异 ;平均动脉压上升达正常范围 (37.4± 8.8mm Hg vs 84.2± 9.7mm Hg,P<0 .0 1) ;中心静脉压显著下降 (14.6± 2 .3cm H2 O vs 4.2± 1.5 cm H2 O,P<0 .0 1) ;肺动脉压无显著性变化 ;肺毛细血管楔压下降 (14± 3.9vs 1.6± 0 .9mm Hg,P<0 .0 1)。结论是全心功能不全时 ,单纯应用左心辅助并不能有效地改善血流动力学状况 ,应用双心室辅助可提高心输出量和动脉压至正常水平 ,可最大限度地减少心脏作功 ,降低氧耗 ,促进心肌组织的修复和代谢。因此 ,在左右心功能明显受损对药物和主动脉内球囊反搏 (IABP)治疗无效时 ,单行左心辅助应慎重 ,双心室辅助是推荐     

Measurement of QRS duration for biventricular pacing optimization

Optimization of left ventricular pacing site or interventricular pacing delay improves the efficacy of biventricular pacing (BiVP). Cardiac output (CO) based optimization, however, is invasive and slow. QRS duration (QRSd) is noninvasive and responds rapidly. Accordingly, we investigated the utility of QRSd for BiVP optimization in a model of acute right ventricular (RV) pressure overload. In seven anesthetized open-chest pigs, BiVP was implemented with right atrial and RV pacing wires. A 6-electrode array was placed behind the LV. Heart block was established by alcohol ablation. The pulmonary artery was snared to double peak RV pressure. Fifty-four combinations of left ventricular pacing site and interventricular pacing delay were tested in random order over 30-second intervals. QRSd was assessed from electrocardiogram lead II, CO from aortic flow probe, and ventricular function from micromanometers. Comparisons were made with the Pearson's correlation coefficient (r). QRSd narrowing was associated with improved RV function and transseptal synchrony, but correlation with CO was poor. Additionally, QRSd averaged over the last 20 cardiac cycles in each interval was compared with values averaged over successive cardiac cycles following each reprogramming. Seven cardiac cycles after reprogramming, the average r-value went above 0.90 and plateaued. QRSd-based optimization merits further study during BiVP in patients with congestive heart failure.     

Clinical evaluation of right ventricular function in patients with left ventricular assist device (LVAD).

Right ventricular function (RVF) during LVAD support can be a threat for patient survival. Despite extensive research, RVF and its interference with left heart function is unclear. This study examines RVF in a retrospective analysis of 14 patients. Hemodynamic data were collected, including heart rate (HR), central venous pressure (CVP), mean pulmonary artery pressure (mPAP), total cardiac output (CO), calculated stroke volume index (SVI) and right ventricular stroke work index (RVSWI). In all patients, CO increased gradually throughout the study period; CVP showed no significant decrease; mPAP and PCWP decreased significantly over the time period; SVI improved and RVSWI increased from the starting level prior to implantation of the LVAD. We conclude that the CO improved with a lowering of the right ventricular afterload combined with a decrease in total circulating volume. The improvement of RVF with LV assist makes this device an option as a bridge to transplant.     

Development of compact ventricular assist device for chronic use

A compact and reliable mechanical ventricular assist device is expected for chronic use. A magnetically suspended centrifugal pump (MSCP) is a seal-less, bearingless pump that can be operated for a long time with-out fear of leak or thrombus formation around the shaft. This paper reports recent progress with the MSCP, including pulse-pressure generation: In three sheep with acute heart failure induced by injection of beta-blockers, left ventricular assist was instituted with an inflow cannula into the left atrium (LA) and left ventricle (LV), and the outflow cannula to the descending aorta. The timing of the pulsation was synchronized with the electrocardiogram. Cardiac performance was evaluated by a conductance catheter and a tipped manometer in the LV. As pump speed increased, the pump flow became almost continuous. After application of pulsation, the pulse pressure increased from 5 to 25 mmHg, irrespective of the inflow cannulation site and the timing of pulsation. With LA cannulation, LV pressure at copulsation was slightly higher than at counterpulsation. Chronic animal trial: The MSCP was implanted in three sheep. The inflow cannula was inserted into the LV. The native heart was kept intact. The inner surface was coated with heparin. Continuous hemodynamic monitoring as well as periodic blood sampling was performed. The duration of running of the pump was 60, 140, and 248 days. The causes of termination were infection and failure of magnetic suspension due to electrical short. No thrombus or embolic findings were observed in the whole body after sacrifice. Renal and hepatic functions were within normal range throughout the experiment. It is concluded that the MSCP can produce pulsation irrespective of the inflow cannulation site and timing of synchronization. It is a promising device for chronic ventricular support.     

The effects of left atrial and left ventricular cannulation on left ventricular function

A study in anesthetised dogs was undertaken to investigate the immediate effects of cannulation of the heart for left heart bypass on left ventricular function. Twenty-six mongrel dogs were studied. In the first group of 13 dogs (Group A), left atrial cannulation was performed through the atrial appendage and in the second group of 13 dogs (Group B), the left ventricular apex was also cannulated. Systemic blood pressure, heart rate, left atrial pressure, left ventricular end diastolic pressure and dP/dT showed no difference in left ventricular function between Groups A and B. Global ejection fraction (EF) measured by injection of technetium99m-labelled human serum albumen with gated left ventricular imaging, showed no significant difference between the two groups but analysis of the regional contribution to global EF in Group B dogs demonstrated a significant reduction in left ventricular function at the site of ventricular cannulation (P less than 0.05). These findings, together with other reported disadvantages of left ventricular cannulation, suggest that the left atrium is the preferred site for cannulation when left heart bypass is required. Many reports attest to the value of mechanical circulatory support in patients with ventricular dysfunction who cannot be weaned from cardiopulmonary bypass (2, 4, 10, 11, 15). Initial support is commonly provided by an intra-aortic balloon pump but, in more severe cases, use of a left ventricular assist device may be warranted. More recently, such devices have also been employed in the management of patients with cardiogenic shock refractory to medical therapy (10).(ABSTRACT TRUNCATED AT 250 WORDS)     

Myocardial remodeling and bioelectric changes in tachycardia-induced heart failure in dogs

In this study, electrical and structural remodeling of ventricles was examined in tachycardia-induced heart failure (HF). We studied two groups of weight-matched adult male mongrel dogs: a sham-operated control group (n=5) and a pacing group (n=5) that underwent ventricular pacing at 230 bpm for 3 weeks. Clinical symptoms of congestive HF were observed in both groups. Their hemodynamic parameters were determined and the severity of the HF was evaluated by M-mode echocardiography. Changes in heart morphology were observed by scanning electron and light microscopy. Ventricular action potential duration (APD), as well as the 50 and 90% APD were measured in both groups. All dogs exhibited clinical symptoms of congestive HF after rapid right ventricular pacing for 3 weeks. These data indicate that rapid, right ventricular pacing produces a useful experimental model of low-output HF in dogs, characterized by biventricular pump dysfunction, biventricular cardiac dilation, and non-ischemic impairment of left ventricular contractility. Electrical and structural myocardial remodeling play an essential role in congestive HF progression, and should thus be prevented.     

Biventricular support with the Jarvik 2000 axial flow pump: a feasibility study

Patients with congestive heart failure who are supported with a left ventricular assist device (LVAD) may experience right ventricular dysfunction or failure that requires support with a right ventricular assist device (RVAD). To determine the feasibility of using a clinically available axial flow ventricular assist device as an RVAD, we implanted Jarvik 2000 pumps in the left ventricle and right atrium of two Corriente crossbred calves (approximately 100 kg each) by way of a left thoracotomy and then analyzed the hemodynamic effects in the mechanically fibrillated heart at various LVAD and RVAD speeds. Right atrial implantation of the device required no modification of either the device or the surgical technique used for left ventricular implantation. Satisfactory biventricular support was achieved during fibrillation as evidenced by an increase in mean aortic pressure from 34 mm Hg with the pumps off to 78 mm Hg with the pumps generating a flow rate of 4.8 L/min. These results indicate that the Jarvik 2000 pump, which can provide chronic circulatory support and can be powered by external batteries, is a feasible option for right ventricular support after LVAD implantation and is capable of completely supporting the circulation in patients with global heart failure.     

Analysis of the relationship between left ventricular pressure and motor current for evaluation of native cardiac function during left ventricular support with a centrifugal blood pump

Control of the ventricular assist device (VAD) for native heart preservation should be attempted, and the VAD could be one strategy for dealing with the shortage of donors in the future. In the application of nonpulsatile blood pumps for ventricular assistance from the ventricular apex to the aorta, bypass flow and hence the motor current of the pumps change in response to the ventricular pressure change. Utilizing these intrinsic characteristics of the continuous-flow pumps, in this study we investigated whether motor current could be used as an index for continuous monitoring of native cardiac function. In study 1, a centrifugal blood pump (CFP) VAD was installed between the apex and descending aorta of a mock circulatory loop. In this model, a baseline with a preload of 10 mmHg, afterload of 40 mmHg, and LV systolic pressure of 40 mmHg was used. The pump speed was fixed at 1300, 1500, and 1700 rpm, and LV systolic pressure was increased up to 140 mmHg by steps of 20 mmHg while the changes in LV pressure, motor current, pump flow, and aortic pressure were observed. In study 2, an in vivo experiment was performed using three sheep. A left heart bypass model was created using a centrifugal pump from the ventricular apex to the descending aorta. The LVP was varied through administration of dopamine while the changes in LV pressure, pump flow, and motor current at 1500 and 1700 rpm were observed. An excellent correlation was observed in both in vitro and in vivo studies in the relationship between motor current and LV pressure. In study 1, the correlation coefficients were 0.77, 0.92, and 0.99 for 1300, 1500, and 1700 rpm, respectively. In study 2, they were 0.88 (animal no. 1), 0.83 (animal no. 2), and 0.88 (animal no. 3) for 1500 rpm, and 0.95 (animal no. 2) and 0.93 (animal no. 3) for 1700 rpm. These results suggest that motor current amplitude monitoring could be useful as an index for the control of VAD for native heart preservation.     

Quantification of interventricular dyssynchrony during continuous-flow left ventricular assist device support

Journal of Artificial Organs - Under continuous-flow left ventricular assist device (CF-LVAD) support, the ventricular volume change and cardiac cycle between the left ventricle (LV) and right...     

Tricuspid valve repair in patients supported with left ventricular assist devices

In patients with end-stage heart failure, severe tricuspid regurgitation (TR) might be one of the signs of biventricular failure with subsequent need for biventricular support (biventricular assist device [BVAD]) or total artificial heart (TAH). However, tricuspid valve repair (TVR) may avoid BVAD or TAH implantation. Consecutive patients with TR of grade 3+ receiving either left ventricular assist device with concomitant TVR (group A, n = 7) or a BVAD/TAH (group B, n = 18) implanted in our institution between 2007 and 2010 were compared retrospectively. Intermacs (Interagency Registry for Mechanically Assisted Circulatory Support) stage I, age less than 18 years, and postcardiotomy failure were the exclusion criteria. Preoperative parameters were similar in both groups. No differences in 30-day mortality (28.5% vs. 22.2%, p = 0.8), postoperative dialysis, intensive care unit (ICU) stay (35 vs. 22 days, p = 0.94), or ventilation time (15 vs. 13 days) were seen. Timing of discharge home was similar in both groups (42.8% after a median of 45 days vs. 50% after a median of 40 days [p = 0.78]). Six months after surgery, no significant TR was seen in group A. Right ventricular failure requiring mechanical support occurred in 14.2% (n = 1) in group A. In patients with TR of grade 3+, left ventricular assist device support combined with TVR showed comparable results with biventricular support with regard to short-term outcome. These results led to a change of our established ventricular assist device implantation strategy.     

Factors reducing left and right ventricular output during simultaneous atrioventricular activation in the pig heart

Forward stroke volume fell by 26% (23-30%) (median and 95% confidence interval) when simultaneous atrioventricular (AV) pacing was induced at constant heart rate in 10 anaesthetized open-chest pigs. To assess the relative importance of factors which could cause this reduction in right and left ventricular (RV and LV) output, we compared cardiac dynamics when either ventricular filling or forward stroke volume was equally reduced by caval constriction and simultaneous AV pacing. We estimated the degree of ventricular filling by recording segment lengths (SL) in the free walls of both ventricles. Our analysis revealed that abolished active LV filling by the left atrium reduced forward stroke volume by 11% (8-14%). The remaining fall in output could be attributed to mitral regurgitation. In the right side of the heart the response was different. The drop in RV filling during simultaneous AV pacing accounted for approximately one-half of the fall in forward RV stroke volume. Estimates based on SL recordings demonstrated that forward RV stroke volume fell by 7% (2-25%) because of tricuspidal regurgitation. Pulmonary artery pressure was 4.5 (3.4-5.7) mmHg higher during simultaneous AV pacing than during caval constriction, representing a relative rise in afterload that reduced the RV stroke volume by 6-8%. Thus, reduced ventricular filling during simultaneous AV pacing accounted for approximately one-half of the drop in forward output from both ventricles. Slightly more than one-half of the reduction in forward LV stroke volume could be attributed to mitral regurgitation. In the right side of the heart tricuspidal regurgitation and a relative rise in pulmonary artery pressure each accounted for about one-quarter of the fall in forward RV output.     

Recovery directed left ventricular assist device: a new concept

To promote cardiac recovery, we developed a recovery directed left ventricular assist device (RDLVAD) that consists of a valved apical conduit, an afterload controlling chamber (ACC), and a pump. We evaluated its efficacy by comparison with an ordinary LVAD. In each of six pigs with ischemia-induced heart failure, flow and pressure measurements were made while maintaining the total blood flow and arterial pressure equal in the two groups. RDLVAD was able to direct all the blood ejected from the LV into the ACC (0-15 mm Hg) but not into the aorta (73 mm Hg). In the ordinary LVAD, however, some ejection occurred into the aorta despite vigorous suction of the LV. Thus, RDLVAD increased DPTI/SPTI 2.3 times (p < 0.005) and decreased left ventricular end-diastolic pressure by 40% and maximum dP/dt by 20% (p < 0.05). Even the apical valve, at approximately half the diameter of the aortic valve, was able to allow all the blood ejected from the LV to enter the ACC. In one control group pig that achieved almost no ejection into the aorta, left ventricular relaxation and dilatation was extremely limited. RDLVAD may promote cardiac recovery by ensuring less LV work, a greater blood supply/demand ratio in the coronary circulation, and full ventricular relaxation.     

Transesophageal left ventricular electrogram-recording and temporary pacing to improve patient selection for cardiac resynchronization

Cardiac resynchronization therapy (CRT) with biventricular pacing (BV) is an established therapy for heart failure (HF) patients with inter- and intraventricular conduction delay. The aim of this pilot study was to test the feasibility of both transesophageal measurement of left ventricular (LV) electrical delay and transesophageal LV pacing prior to implantation, to better select patients for CRT. Esophageal TO8 Osypka catheter was perorally applied in 30 HF patients in position of maximum LV deflection to measure LV electrical delay and to study arterial pulse pressure (PP) during transesophageal bipolar LV pacing. There were 15 responders with a PP increase of a mean 65 ± 24 mmHg to 79 ± 27 mmHg (P < 0.001) and a mean LV electrical delay of 86.8 ± 33 ms. The 15 non-responders with poor PP increase of a mean 63.5 ± 23.5 mmHg to 64.1 ± 23.9 mmHg (P = 0.065) had a significantly smaller LV electrical delay of 36 ± 21 ms (P < 0.001). During a 34 ± 26 month CRT follow-up, the responders New York Heart Association (NYHA) class improved from 3.1 ± 0.35 to 2.1 ± 0.35 (P < 0.001). Determination of left ventricular electrical delay by transesophageal electrogram recording and transesophageal left ventricular pacing may be additional useful techniques to improve patient selection for CRT.     

Medroxyprogesterone acetate aggravates oxidative stress and left ventricular dysfunction in rats with chronic myocardial infarction

The role of estrogens during myocardial ischemia has been extensively studied. However, effects of a standard hormone replacement therapy including 17β-estradiol (E2) combined with medroxyprogesterone acetate (MPA) have not been assessed, and this combination could have contributed to the negative outcomes of the clinical studies on hormone replacement. We hypothesized that adding MPA to an E2 treatment would aggravate chronic heart failure after experimental myocardial infarction (MI). To address this issue, we evaluated clinical signs of heart failure as well as left ventricular (LV) dysfunction and remodeling in ovariectomized rats subjected to chronic MI receiving E2 or E2 plus MPA. After eight weeks MI E2 showed no effects. Adding MPA to E2 aggravated LV remodeling and dysfunction as judged by increased heart weight, elevated myocyte cross-sectional areas, increased elevated left ventricle end diastolic pressure, and decreased LV fractional shortening. Impaired LV function in rats receiving MPA plus E2 was associated with increased cardiac reactive oxygen species generation and myocardial expression levels of NADPH oxidase subunits. These results support the interpretation that adding MPA to an E2 treatment complicates cardiovascular injury damage post-MI and therefore contributes to explain the adverse outcome of prospective clinical studies.     

Mono and bi-ventricular assistance: their effect on ventricular energetics

When mono- and bi-ventricular mechanical assistance is used for heart recovery, its control strategy and circulatory variables affect ventricular energetics (external work-EW, oxygen consumption-VO2, cardiac mechanical efficiency-CME). This study is based on the data obtained in vitro and presents an analysis of the effects of the mono- and bi-ventricular mechanical assistance on ventricular energetics. The assistance was conducted on the principle of counterpulsation with atrio-arterial connection. It includes the following stages: 1) the characterisation of the isolated ventricle model in terms of EW, VO2 and CME as a function of the filling pressure and peripheral resistance, 2) modelling of left ventricular and pulmonary dysfunction, followed by left ventricular and bi-ventricular assistance. Experimental data enable us to draw the following conclusions: * in general, the greatest hemodynamic improvement does not correspond to the highest energetic improvement, * LVAD assistance deteriorates left ventricular CME while its effect on right ventricular energetics depends on the value of right ventricular elastance (Emax). Right ventricular CME is deteriorated by BVAD assistance irrespective of right Emax, * the energetics optimisation in bi-ventricular assistance is closely related to the right Emax, which could probably be a deciding factor in the choice of the assistance mode.     

Simulation of systolic and diastolic left ventricular dysfunction in a mock circulation: the effect of arterial compliance

Arterial compliance (AC) is expected to play a major role on cardiac efficacy by acute or long-term mechanisms. The aim of this study was to investigate the purely mechanical effect of AC on left ventricular (LV) performance, for different conditions of LV dysfunction (systolic versus diastolic). A hydraulic, Windkessel model of systemic circulation was used. LV function and aortic flow were simulated using a left ventricular assist device (LVAD). Two cases of LV dysfunction were simulated: Case A, systolic and Case B, diastolic dysfunction. In Case A, AC increased from 1.14 to 2.85 ml mm Hg(-1) leading to an increase in LVAD stroke volume up to 6%, while no significant effect was observed in Case B. LVAD systolic work was decreased by 4% in systolic and by 11% in diastolic LVAD dysfunction. The purely mechanical effect of AC changes on LVAD function was different between systolic and diastolic dysfunction. It might be expected that even an acute reduction in arterial stiffness could enhance LV performance by different means in systolic compared to diastolic dysfunction.