Remission From Stage D Heart Failure (RESTAGE-HF): Early Results From a Prospective Multi-Center Study of Myocardial Recovery

Recovery From Exhaustion of the Frank-Starling Mechanism by Mechanical Unloading With a Continuous-Flow Ventricular Assist Device

BACKGROUND

We describe our original left ventricular assist device (LVAD) speed ramp and volume loading test designed to evaluate native heart function under continuous-flow LVAD support.Methods and Results:LVAD speed was decreased in 4 stages from the patient's optimal speed to the minimum setting for each device. Under minimal LVAD support, patients were subjected to saline loading (body weight [kg]×10 mL in 15 min). Echocardiographic and hemodynamic data were obtained at each stage of the LVAD speed ramp and every 3 min during saline loading. Patients were divided into Recovery (with successful LVAD removal; n=8) and Non-recovery (others; n=31) groups. During testing, increased pulmonary capillary wedge pressure caused by volume loading was milder in the Recovery than Non-recovery group (repeated measures analysis of variance; group effect, P=0.0069; time effect, P<0.0001; interaction effect, P=0.0173). Increased cardiac output from volume loading was significantly higher in the Recovery than Non-recovery group (group effect, P=0.0124; time effect, P<0.0001; interaction effect, P=0.0091). Therefore, the Frank-Starling curve of the Recovery group was located upward and to the left of that of the Non-recovery group.

CONCLUSIONS

The LVAD speed ramp and volume loading test facilitates the precise evaluation of native heart function during continuous-flow LVAD support.

An in silico twin for epicardial augmentation of the failing heart

Advances in ventricular assist device (VAD) technology for the treatment of end-stage congestive heart failure (CHF) are needed to cope with the increasing numbers of patients that cannot be provided with donor hearts for transplantation. We develop and investigate a novel extravascular VAD technology that provides biventricular, epicardial pressure support for the failing heart. This novel VAD concept avoids blood contact that is accompanied with typical complications such as coagulation and infections. To date, in vivo porcine model results with a prototype of the implant exist, further studies to improve the implant's performance and promote its applicability in humans are needed. In this contribution, we present a personalised functional digital twin of the heart, the vascular system, and the novel VAD technology in terms of a calibrated, customized computational model. The calibration procedure is based on patient-specific measurements and is performed by solving an inverse problem. This in silico model is able to (a) confirm in vivo experimental data, (b) predict healthy and pathologic ventricular function, and (c) assess the beneficial impact of the novel VAD concept to a high level of fidelity. The model shows very good agreement with in vivo data and reliably predicts increases in stroke volume and left ventricular pressure with increasing ventricular support. Furthermore, the digital twin allows insight into quantities that are poorly or not at all amenable in any experimental setup. Conclusively, the model's ability to link integral hemodynamic variables to local tissue mechanical deformation makes it a highly valuable tool for the dimensioning of novel VAD technologies and future treatment strategies in heart failure. The presented in silico twin enhances in vivo studies by facilitating the accessibility and increasing the range of quantities of interest. Because of its flexibility in the assessment of design variants and optimization loops, it may substantially contribute to a reduction of the amount of animal experiments in this and similar settings.

Outflow Cannula Systolic Slope in Patients With Left Ventricular Assist Devices: A Novel Marker of Myocardial Contractility

Left ventricular (LV) unloading with a LV assist device (LVAD) reverse remodels the heart and may lead to favorable changes in cellular architecture and LV geometry promoting myocardial recovery. Currently, there are no standardized methods for evaluating myocardial recovery. This study assesses the systolic slope of the LVAD outflow cannula as a marker for myocardial contractility. Doppler echocardiography (transthoracic echocardiogram [TTE]) of the LVAD outflow cannula and TTE of the LV cavity were prospectively collected in 57 patients with LVADs. Systolic acceleration of the LVAD outflow cannula was measured in each patient as the peak change of velocity over time (dv/dt) during systole from continuous-wave Doppler signal acquired from the LVAD outflow cannula. Ventricular volumes were concurrently measured by TTE. In a subset of 10 patients, the systolic slope was measured during each stage of a ramp study to study the properties of this parameter across a variety of loading conditions. The systolic slope of the LVAD outflow cannula was successfully measured in 53 of 57 patients (93%). Systolic slope strongly correlated with ejection fraction (EF) (R = 0.92). Analysis of systolic slope stratified by EF (EF >30%, EF 20-30%, EF 10-20%, and EF <10%) revealed systolic slopes that were significantly different between the groups (1,371 cm/s ± 324; 983 cm/s ± 122; 578 cm/s ± 139; and 495 cm/s ± 107, respectively; p < 0.001). Systolic slope did not change significantly across variable preload and afterload conditions during a ramp study. Systolic slope of the LVAD outflow cannula strongly correlates with EF and can be used to assess underlying myocardial contractility across a variety of LVAD loading conditions.

Controversies and Challenges of Ventricular Assist Device Therapy

Left ventricular assist device (LVAD) therapy has emerged as an increasingly vital facet of the treatment algorithm for advanced heart failure. Growing experience with LVAD support has led to substantial improvements in outcomes, with 1-year survival rates approaching that of cardiac transplantation. These therapeutic refinements have engendered growing interests in the potential for expanding the clinical indications for LVAD therapy to patients with less advanced heart failure. The primary obstacles to this evolution of care center largely on the prevention and/or management of the adverse events associated with LVAD therapy along with patient preference. Many programs also face the mounting difficulty of balancing quality outcomes with the increased volume of implants. During the recently assembled Users Meeting organized by St. Jude Medical, heart failure clinicians from nearly 50 LVAD implanting centers discussed these and other challenges and controversies impacting the field. The present review summarizes the key insights gleaned from this meeting.

Left Ventricular Assist Devices for Lifelong Support

Continuous-flow left ventricular assist devices (LVADs) have revolutionized advanced heart failure care. These compact, fully implantable heart pumps are capable of providing meaningful increases in survival, functional capacity, and quality of life. Implantation volumes continue to grow, but several challenges remain to be overcome before LVADs will be considered as the therapy of choice for all patients with advanced heart failure. They must be able to consistently extend survival for the long term (7 to 10 years), rather than the midterm (3 to 5 years) more typical of contemporary devices; they must incorporate design elements that reduce shear stress and avoid stasis to reduce the frequent adverse events of bleeding, stroke, and pump thrombosis; and they must become more cost-effective. The advancements in engineering, implantation technique, and medical management detailed in this review will highlight the progress made toward achieving lifelong LVAD support and the challenges that remain.

Anesthesia for Heart Transplantation

This article seeks to evaluate current practices in heart transplantation. The goals of this article were to review current practices for heart transplantation and its anesthesia management. The article reviews current demographics and discusses the current criteria for candidacy for heart transplantation. The process for donor and receipt selection is reviewed. This is followed by a review of mechanical circulatory support devices as they pertain to heart transplantation. The preanesthesia and intraoperative considerations are also discussed. Finally, management after transplantation is also reviewed.