Impact of right ventricular and pulmonary vascular characteristics on Impella hemodynamic support in biventricular heart failure: A simulation study

BACKGROUND

Impella (Abiomed, Danvers, MA, USA) is a percutaneous ventricular assist device commonly used in cardiogenic shock, providing robust hemodynamic support, improving the systemic circulation, and relieving pulmonary congestion. Maintaining adequate left ventricular (LV) filling is essential for optimal hemodynamic support by Impella. This study aimed to investigate the impact of pulmonary vascular resistance (PVR) and right ventricular (RV) function on Impella-supported hemodynamics in severe biventricular failure using cardiovascular simulation.

METHODS

We used Simulink® (Mathworks, Inc., Natick, MA, USA) for the simulation, incorporating pump performance of Impella CP determined using a mock circulatory loop. Both systemic and pulmonary circulation were modeled using a 5-element resistance-capacitance network. The four cardiac chambers were represented by time-varying elastance with unidirectional valves. In the scenario of severe LV dysfunction (LV end-systolic elastance set at a low level of 0.4 mmHg/mL), we compared the changes in right (RAP) and left atrial pressures (LAP), total systemic flow, and pressure-volume loop relationship at varying degrees of RV function, PVR, and Impella flow rate.

RESULTS

The simulation results showed that under low PVR conditions, an increase in Impella flow rate slightly reduced RAP and LAP and increased total systemic flow, regardless of RV function. Under moderate RV dysfunction and high PVR conditions, an increase in Impella flow rate elevated RAP and excessively reduced LAP to induce LV suction, which limited the increase in total systemic flow.

CONCLUSIONS

PVR is the primary determinant of stable and effective Impella hemodynamic support in patients with severe biventricular failure.

Dynamic load modulation predicts right heart tolerance of left ventricular cardiovascular assist in a porcine model of cardiogenic shock

Ventricular assist devices (VADs) offer mechanical support for patients with cardiogenic shock by unloading the impaired ventricle and increasing cardiac outflow and subsequent tissue perfusion. Their ability to adjust ventricular assistance allows for rapid and safe dynamic changes in cardiac load, which can be used with direct measures of chamber pressures to quantify cardiac pathophysiologic state, predict response to interventions, and unmask vulnerabilities such as limitations of left-sided support efficacy due to intolerance of the right heart. We defined hemodynamic metrics in five pigs with dynamic peripheral transvalvular VAD (pVAD) support to the left ventricle. Metrics were obtained across a spectrum of disease states, including left ventricular ischemia induced by titrated microembolization of a coronary artery and right ventricular strain induced by titrated microembolization of the pulmonary arteries. A sweep of different pVAD speeds confirmed mechanisms of right heart decompensation after left-sided support and revealed intolerance. In contrast to the systemic circulation, pulmonary vascular compliance dominated in the right heart and defined the ability of the right heart to adapt to left-sided pVAD unloading. We developed a clinically accessible metric to measure pulmonary vascular compliance at different pVAD speeds that could predict right heart efficiency and tolerance to left-sided pVAD support. Findings in swine were validated with retrospective hemodynamic data from eight patients on pVAD support. This methodology and metric could be used to track right heart tolerance, predict decompensation before right heart failure, and guide titration of device speed and the need for biventricular support.

Performance of the Jarvik 2000 left ventricular assist device on mid-term hemodynamics and exercise capacity

The hemodynamic and exercise capacity performance of the Jarvik 2000 left ventricular assist device (LVAD), which is generally used in patients with small body size and relatively preserved cardiac function, is not well understood. We retrospectively examined 18 patients implanted with the Jarvik 2000 LVAD. Pump rotation speed was optimized by the hemodynamic ramp test one year after implantation based on the criteria of mean pulmonary capillary wedge pressure (PCWP) < 18 mmHg, mean right atrial pressure (RAP) < 12 mmHg, and cardiac index (CI) > 2.2 L/min/m² as well as echocardiographic parameters. Exercise capacity was assessed by cardiopulmonary exercise test in an optimized setting. To investigate the impacts of larger body surface area (BSA) and extremely impaired pre-implantation cardiac function on hemodynamics and exercise capacity, two correlation analyses based on BSA and original CI were performed. At a pump speed of 9500 ± 707 rpm, the mean pulmonary artery pressure, PCWP, RAP, and CI were 17 ± 5 mmHg, 9 ± 5 mmHg, 6 ± 4 mmHg, and 2.82 ± 0.54 L/min/m², respectively. Only one patient failed to achieve the hemodynamic criteria. The peak VO₂ and VE/VCO₂ slope were 12.9 ± 3.1 mL/min/kg and 37.7 ± 15.0, respectively. There was an inverse correlation between original CI and heart rate (r = -0.60, p  =  0.01), and a weak correlation between BSA and PCWP (r  =  0.43, p  =  0.08). Based on this study, the overall performance of the Jarvik 2000 device was acceptable, and the patients' body size and original cardiac function had minimum effect on the performance of this device.

Outcome of right ventricular assist device implantation following left ventricular assist device implantation: Systematic review and meta-analysis

Objectives:

The main aim was a systematic evaluation of the current evidence on outcomes for patients undergoing right ventricular assist device (RVAD) implantation following left ventricular assist device (LVAD) implantation.

Methods:

This systematic review was registered on PROSPERO (CRD42019130131). Reports evaluating in-hospital as well as follow-up outcome in LVAD and LVAD/RVAD implantation were identified through Ovid Medline, Web of Science and EMBASE. The primary endpoint was mortality at the hospital stay and at follow-up. Pooled incidence of defined endpoints was calculated by using random effects models.

Results:

A total of 35 retrospective studies that included 3260 patients were analyzed. 30 days mortality was in favour of isolated LVAD implantation 6.74% (1.98–11.5%) versus 31.9% (19.78–44.02%) p = 0.001 in LVAD with temporary need for RVAD. During the hospital stay the incidence of major bleeding was 18.7% (18.2–19.4%) versus 40.0% (36.3–48.8%) and stroke rate was 5.6% (5.4–5.8%) versus 20.9% (16.8–28.3%) and was in favour of isolated LVAD implantation. Mortality reported at short-term as well at long-term was 19.66% (CI 15.73–23.59%) and 33.90% (CI 8.84–59.96%) in LVAD respectively versus 45.35% (CI 35.31–55.4%) p ⩽ 0.001 and 48.23% (CI 16.01–80.45%) p = 0.686 in LVAD/RVAD group respectively.

Conclusion:

Implantation of a temporary RVAD is allied with a worse outcome during the primary hospitalization and at follow-up. Compared to isolated LVAD support, biventricular mechanical circulatory support leads to an elevated mortality and higher incidence of adverse events such as bleeding and stroke.

Longitudinal Trajectories of Hemodynamics Following Left Ventricular Assist Device Implantation

BACKGROUND

Continuous-flow left ventricular assist devices (LVADs) improve the hemodynamics of patients with advanced heart failure. However, the longitudinal trajectories of hemodynamics in patients after LVAD implantation remain unknown. The aim of this study was to investigate the trends of hemodynamic parameters following LVAD implantation.

METHODS AND RESULTS

We retrospectively reviewed patients who underwent LVAD implantation between April 2014 and August 2018. We collected hemodynamic parameters from right heart catheterizations. Of 199 consecutive patients, we enrolled 150 patients who had both pre- and postimplant right heart catheterizations. They had 3 (2, 4) postimplant right heart catheterizations during a follow-up of 2.3 (1.3, 3.1) years. The mean age was 57 ± 13 years, and 102 patients (68%) were male. Following LVAD implantation, pulmonary arterial pressure and pulmonary capillary wedge pressure decreased, and cardiac index increased significantly, then remained unchanged throughout follow-up. Right atrial pressure decreased initially and then gradually increased to preimplant values. The pulmonary artery pulsatility index decreased initially and returned to preimplant values, then progressively decreased over longer follow-up. Subgroup analysis showed significant differences in the trajectories of the pulmonary artery pulsatility index based on gender.

CONCLUSIONS

Despite improvement in left-side filling pressures and cardiac index following LVAD implantation, right atrial pressure increased and the pulmonary artery pulsatility index decreased over time, suggesting progressive right ventricular dysfunction.

Pulmonary artery pressure may be a predictor of closed aortic valve in patients managed by venoarterial extracorporeal membrane oxygenation

In the management of venoarterial extracorporeal membrane oxygenation, some patients present persistently closed aortic valve. However, little is known about the variables that contribute to persistently closed aortic valve. We investigated the factors that could predict persistently closed aortic valve at the time of venoarterial extracorporeal membrane oxygenation initiation. We investigated 17 patients who presented closed aortic valve immediately after the introduction of venoarterial extracorporeal membrane oxygenation. Patients who presented closed aortic valve 24 h after introduction of venoarterial extracorporeal membrane oxygenation were defined as the Closed-AV group (n = 8), while those whose aortic valve remained opened after 24 h were defined as the Open-AV group (n = 9). All patients were managed by concomitant use of intra-aortic balloon pumping. At baseline, there were no significant differences between mean arterial blood pressure, central venous pressure, and left ventricular ejection fraction. However, Closed-AV group had significantly lower mean pulmonary artery pressure and pulmonary artery pulse pressure compared to those of Open-AV group (mean pulmonary artery pressure: 15 ± 6 mmHg vs 25 ± 8 mmHg, p = 0.01; pulmonary artery pulse pressure: 3 ± 2 mmHg vs 8 ± 3 mmHg, p < 0.01). Logistic regression analyses revealed that the lower mean pulmonary artery pressure and pulmonary artery pulse pressure had the predictive value of closed aortic valve within 24 h after venoarterial extracorporeal membrane oxygenation initiation (mean pulmonary artery pressure: odds ratio = 0.78, 95% confidence interval = 0.58-0.95, p < 0.01; pulmonary artery pulse pressure: odds ratio = 0.18, 95% confidence interval = 0.01-0.61, p < 0.01). Lower mean pulmonary artery pressure and pulmonary artery pulse pressure values could predict persistent closed aortic valve 24 h after venoarterial extracorporeal membrane oxygenation initiation. Left ventricular preload derived from right heart function may have a major impact on aortic valve status.

First Experience of Transfer with Impella 5.0 Over the Long Distance in Japan

We recently experienced a 43-year-old man with dilated cardiomyopathy transported under the Impella support to a high-volume left ventricular assist device (LVAD) center. Stabilized hemodynamics with the Impella and firm fixation of the device were important for safe transportation of the patient.

Mechanical circulatory support for the right ventricle in combination with a left ventricular assist device

Introduction: Right heart failure (RHF) in patients with a left ventricular assist device (LVAD) carries a poor prognosis although the treatment strategy including mechanical circulatory support for the failing right ventricle (RV) has not been well established. Areas covered: In this review, we describe an overview of RHF post-LVAD implant including natural history, prevalence, pathophysiology, outcomes, and challenges to predict RHF post-LVAD implant. Then, we focus on right ventricular assist devices (RVADs) and their clinical outcomes. Recently developed percutaneous RVADs are the major advance in this field. Finally, we discuss future perspectives to overcome limitations of the current treatment options. Expert opinion: In the absence of dedicated RVAD system RHF post-LVAD implant may have been undertreated. Now that dedicated percutaneous RVADs have emerged, surgeons are encouraged to use these new devices to improve outcomes of LVAD therapy. As experience accumulates, we should be able to establish the best possible strategy to treat early RHF post-LVAD implant. Late RHF is another form of RHF post-LVAD implant and has been underappreciated. Further research is mandatory to clarify the mechanism and risk factors. There are still unmet needs for a dedicated implantable RVAD for a subset of patients who need long-term RV support.

Right ventricular failure management

PURPOSE OF REVIEW

Review recent advances in the diagnosis and management of right ventricular (RV) failure.

RECENT FINDINGS

Temporary and durable device-based management of RV failure has emerging applications.

SUMMARY

Research advances and clinical management in RV failure have been limited by a lack of consensus on a universal definition. Echocardiographic and cardiac MRI-based predictors of RV failure are imperfect. Combinations of hemodynamic and imaging variables may have better predictive value. Loading conditions and ventriculo-arterial coupling play important roles in RV function. The current treatment approach to RV failure includes a combination of inotropy and vasodilatation but lacks conclusive evidence. Emerging biochemical and molecular targets hold promise but have yet to be proven in human studies.