Biventricular Assist Device Research Articles

Utilization and Outcomes of Temporary Mechanical Circulatory Support for Graft Dysfunction After Heart Transplantation.

Graft dysfunction is the main cause of early mortality after heart transplantation. In cases of severe graft dysfunction, temporary mechanical circulatory support (TMCS) may be necessary. The aim of this systematic review was to examine the utilization and outcomes of TMCS in patients with graft dysfunction after heart transplantation. Electronic search was performed to identify all studies in the English literature assessing the use of TMCS for graft dysfunction. All identified articles were systematically assessed for inclusion and exclusion criteria. Of the 5,462 studies identified, 41 studies were included. Among the 11,555 patients undergoing heart transplantation, 695 (6.0%) required TMCS with patients most often supported using venoarterial extracorporeal membrane oxygenation (79.4%) followed by right ventricular assist devices (11.1%), biventricular assist devices (BiVADs) (7.5%), and left ventricular assist devices (LVADs) (2.0%). Patients supported by LVADs were more likely to be supported longer (p = 0.003), have a higher death by cardiac event (p = 0.013) and retransplantation rate (p = 0.015). In contrast, patients supported with BiVAD and LVAD were more likely to be weaned off support (p = 0.020). Overall, no significant difference was found in pooled 30 day survival (p = 0.31), survival to discharge (p = 0.19), and overall survival (p = 0.51) between the subgroups. Temporary mechanical circulatory support is an effective modality to support patients with graft dysfunction after heart transplantation. Further studies are needed to establish the optimal threshold and strategy for TMCS and to augment cardiac recovery and long-term survival.

O34-1 - A Case Suspected of Stone Heart

Stone heart is ischemic myocardial contracture, known as a rare but devastating complication of cardiopulmonary bypass. We report a case suspected stone heart requiring biventricular assist device (BiVAD). A 54-year old man with mitral valve regurgitation received mitral valve plasty. At the termination of cardio-pulmonary bypass, myocardium became contracted and unable to wean from cardio-pulmonary bypass. Cardioplegia was re-infused antegradely and retrogradely, and intra aortic balloon pumping (IABP) and peripheral extracorporeal membrane oxygenation (pECMO) were immediately installed. He was transferred to our institution for further treatment. Echocardiography showed no systolic contraction with marked thickening of myocardium and substantial decreases in left ventricular cavity. Coronary angiography showed no significant stenosis. Based on these findings, he was diagnosed with stone heart and pECMO was converted to central ECMO. However, no contractility resumed in both ventricle, and a biventricular assist device (BiVAD) was implanted on the 15th day. Histologic examination from right ventricle revealed interstitial and replacement fibrosis associated with mild lymphocyte infiltration. Tl-201 scintigraphy showed perfusion defect at anterior and posterior wall. After tracheotomy, he received systemic care and comprehensive rehabilitation program to become a candidate for heart transplantation. Despite all these maximal efforts, he died of repeated hemorrhagic strokes on the 59th day. Macroscopic findings at autopsy showed extensive necrosis around the heart.

Outcomes of Berlin Heart EXCOR® pediatric ventricular assist device support in patients with restrictive and hypertrophic cardiomyopathy.

The outcomes of pediatric ventricular assist device support in patients with diastolic heart failure have not been well described. This study reviews the North American experience with Berlin Heart EXCOR® ventricular assist device implants in children with such physiology. The Berlin Heart clinical database was reviewed. Patients with primary diastolic dysfunction are included in this study. Twenty pediatric patients with restrictive cardiomyopathy (n=13), hypertrophic cardiomyopathy (n=3), or congenital heart disease with restrictive physiology (n=4) who were supported with EXCOR® were identified. Of these, nine (45%) were successfully bridged to transplant, one (5%) weaned from support, and 10 (50%) died after support was withdrawn. Of patients under age 3years (n=13), 38.5% survived, whereas those aged 3 or older (n=7) had 71.4% survival (P=.35). Biventricular assist device (BiVAD) patients experienced a 27.3% survival, vs 77.8% for patients with left ventricular assist device only (P=.07). Primary causes of death included stroke, infection, acidosis, multisystem organ failure, and bleeding. Pediatric patients with diastolic heart failure comprise a high-risk population for mechanical circulatory support. However, half of patients with this physiology have been successfully supported to explant with EXCOR® . The trends toward higher mortality for younger patients and those receiving BiVAD support warrant consideration.

Rescue Levitronix Centrimag as a bridge to decision: is it still worthwhile?

Cardiogenic shock has poor prognosis with medical management alone and/or intra-aortic balloon pump support. Levitronix Centrimag®centrifugal pump has been increasingly used to bridge patients to decision for further advanced mechanical uni- or bi-ventricular support with a view to heart transplantation on the newly implemented super-urgent recipient scheme. We sought to review our experience as a designated centre for mechanical circulatory support to investigate its role despite the emergence of percutaneously implantable miniature devices. Between April 2009 and December 2015, 98 patients in cardiogenic shock [age 41.4 ± 12.7 years; 52 (53%) male and 46 (47%) female] underwent mechanical circulatory support of whom 90 were treated with Levitronix Centrimag as a primary procedure. Diagnosis was dilated cardiomyopathy [37 (38.1%)], ischaemic cardiomyopathy [25 (25.8%)], and other [36 (36.1%)]. Main indications were cardiogenic shock or decompensated heart failure. Other indications were early graft failure following heart transplant or right ventricular failure following left ventricular assist device insertion. Levitronix support was as follows: extra corporeal membrane oxygenation [22 (24.4%) central, 26 (28.9%) peripheral], Left Ventricular Assist Device [12 (13.3%)], Right Ventricular Assist Device [5 (5.6%)], and Bi-Ventricular Assist Device [25 (27.8%)]. The average duration of support on Levitronix was 17.1 days (range 1–111). The 30-day survival was 52% (47 patients), 6-month survival was 40% (36 patients), and 12-month survival was 37.7% (34 patients). Of the surviving patients, five underwent successful orthotopic heart transplantation, one received a HeartMate II which was subsequently explanted because of myocardial recovery, and one received a HeartMate II and is currently on the transplant list. Cause of death while on support was multiorgan failure [12 (13.3%)], cardiovascular system (CVA)/Neurological [10 (11.1%)], further haemodynamic deterioration [9 (10%)], graft failure [5 (5.6%)], bleeding [4 (4.4%)], sepsis [3 (3.3%)], myocardial infarction [3 (3.3%)], right ventricular failure [3 (3.3%)], pulmonary embolism [1 (1.1%)], embolic [1 (1.1%)], respiratory failure [1 (1.1%)], influenza + rejection [1 (1.1%)], and unknown [3 (3.3%)]. Levitronix Centrimag® remains a versatile device with potential in an acute setting. Early aggressive treatment and a younger patient population may well justify its use.

Pneumatic paracorporeal ventricular assist device as bridge to transplant in children ≤ 20 kg: Krakow experience

Pulsatile mechanical ventricular assist devices (VADs) of various designs and functional principles have been in use in adult patients for long-term support of the failing heart. Despite the remarkable advances with the use of VAD, its support in children is still limited. We report on our experience in the paediatric population. The aim is either recovery of the heart or, more often, to keep the patient alive until later transplantation. We retrospectively study of children ≤ 20 kg, who were mechanically bridged to heart transplantation using the Berlin Heart (BH) Excor VAD at our hospital. The period of review was from November 2009 to March 2017. A total eight patients were included in this analysis, with these patients weighing < 20 kg. The study included three boys and five girls, with a mean weight of 10.55 kg (5.30–20 kg) and mean age of 20.69 months (4.5 to 60 months). Eight patients were supported with the Berlin Excor VAD, and six patients were supported with a left-sided ventricular assist device (LVAD) and two patients were supported with biventricular assist device (BVAD). Three of eight patients (38%) have been successfully bridged to heart transplant. Insertion of pulsatile paracorporeal VADs in children with end-stage heart failure is an effective strategy as a bridge to heart transplantation. This study demonstrates VAD support had serious ceribrovascular complications, and implantation BVAD support results were not satisfactory.

Synergy of first principles modelling with predictive control for a biventricular assist device: In silico evaluation study.

Control for dual rotary left ventricular assist devices (LVADs) used as a biventricular assist device (BiVAD) is challenging. If the control system fails, flow imbalance between the systemic and the pulmonary circulations would result, subsequently leading to ventricular suction or pulmonary congestion. With the expectation that advanced control approaches such as model predictive control could address the challenges naturally and effectively, we developed a synergistic first principles model predictive controller (MPC) for the BiVAD. The internal model of the MPC is a simplified state-space model that has been developed and validated in a previous study. A single Frank-Starling (FS) control curve was used to define the target pump flow corresponding to the preload on each side of the heart. The MPC was evaluated in a validated numerical model using three clinical scenarios: blood loss, myocardial recovery, and exercise. Simulation results showed that the MPC was effective in adapting to changes in physiological states without causing ventricular suction or pulmonary congestion. The use of MPC for a BiVAD eliminates the need for two controllers of dual LVADs thus making the task of controller tuning easier.

Wireless Magnetic Pump : Characteristics of Magnetic Impellers and Medical Application

Wireless magnet pumps are used in medical applications and are particularly useful as artificial heart ventricular assist devices (VADs). To investigate wireless operation of magnetic pumps, we fabricated three types of magnetic impellers using bonded magnets by blending magnetic powders of SmFeN, NdFeB, and Sr-ferrite. We investigated the magnetic properties of the fabricated magnetic impellers, which are driven by the application of magnetic coupling with an external driving magnet or external coil system, without a driving motor, shaft, or mechanical bearings. The use of wireless magnetic pumps is therefore not complicated by critical issues of size, heat, and vibration, which are very important issues for blood pumps. The magnetic properties of the impellers, such as their rotational speed, driving torque and hydrodynamic performance, determine their wireless driving ranges. We conducted performance evaluations of the impeller’s magnetic wireless manipulation, heat, and vibration. In addition, we carried out an animal test to confirm the suitability of the wireless magnetic pumps for use as biventricular assist devices (BiVADs).

(13) - Primary Biventricular Durable Ventricular Assist Devices from Experience North American Centers: A Cautionary Tale

(13) - Primary Biventricular Durable Ventricular Assist Devices from Experience North American Centers: A Cautionary Tale

Outcomes following implantation of mechanical circulatory support in adults with congenital heart disease: An analysis of the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS)

Adults with congenital heart disease represent an expanding and unique population of patients with heart failure (HF) in whom the use of mechanical circulatory support (MCS) has not been characterized. We sought to describe overall use, patient characteristics, and outcomes of MCS in adult congenital heart disease (ACHD). All patients entered into the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) between June 23, 2006, and December 31, 2015, were included. Patients with ACHD were identified using pre-operative data and stratified by ventricular morphology. Mortality was compared between ACHD and non-ACHD patients, and multivariate analysis was performed to identify predictors of death after device implantation. Of 16,182 patients, 126 with ACHD stratified as follows: systemic morphologic left ventricle (n = 63), systemic morphologic right ventricle (n = 45), and single ventricle (n = 17). ACHD patients were younger (42 years ± 14 vs 56 years ± 13; p < 0.0001) and were more likely to undergo device implantation as bridge to transplant (45% vs 29%; p < 0.0001). A higher proportion of ACHD patients had biventricular assist device (BiVAD)/total artificial heart (TAH) support compared with non-ACHD patients (21% vs 7%; p < 0.0001). More ACHD patients on BiVAD/TAH support were INTERMACS profile 1 compared with patients on systemic left ventricular assist device (LVAD) support (35% vs 15%; p = 0.002). ACHD and non-ACHD patients with LVADs had similar survival; survival was worse for patients on BIVAD/TAH support. BiVAD/TAH support was the only variable independently associated with mortality (early phase hazard ratio 4.4; 95% confidence interval, 1.8-11.1; p = 0.001). For ACHD patients receiving MCS, ventricular morphology was not associated with mortality. ACHD patients with LVADs have survival similar to non-ACHD patients. Mortality is higher for patients requiring BiVAD/TAH support, potentially owing to higher INTERMACS profile. These outcomes suggest a promising role for LVAD support in ACHD patients as part of the armamentarium of therapies for advanced HF.

The Flexible Inflow Conduit for Baylor Gyro Permanently Implantable Centrifugal Blood Pump as a Biventricular Assist Device (BVAD) System

A suction phenomenon is well known as one of the major complications in the development of implantable centrifugal blood pump. A flexible inflow conduit was designed to maintain the proper geometry of the implanted inlet with the ventricular camber. Objective : The hypothesis was that the requirement power of the Gyro PI pump having a flexible inflow conduit would decrease if the suction phenomenon were avoided. Methods : Eight bovine cases were implanted with the Gyro PI pumps as a biventricular assist device(BVAD)system. The left pump was bypassed from the left ventricular apex to the descending aorta, and the right pump bypassed the right infundibulum to the main pulmonary artery. Activated clotting time(ACT)was maintained 200 to 250 seconds using heparin. The experimental animals were divided into two groups for retrospective comparison studies. Group A used the Gyro PI pump without a flexible inflow conduit and Group B used the Gyro PI pump with a flexible inflow conduit. Results : The Gyro PI pumps with this flexible conduit(Group B)were implanted into four calves. Ease of implantation, ease of inflow insertion and stable hemodynamic was demonstrated during these surgical feasibility studies. The requiring power of the pump for Group B was significantly reduced compared to that of the Group A, even though no statistical differences in pump flow rate were evident between the groups. There were no significant differences between group A and group B in the hemolysis parameters. And there was no thrombus formation observed in the flexible inflow conduit during necropsy. Conclusions : A new flexible inflow conduit was designed to be placed between the native heart and the artificial heart. The flexible conduit eliminated the suction phenomenon and greatly improved the efficiency of the pump system. 原 著

Right Ventricular Failure Post LVAD Implantation Corrected with Biventricular Support: An In Vitro Model

Right ventricular failure after left ventricular assist device (LVAD) implantation is associated with high mortality. Management remains limited to pharmacologic therapy and temporary mechanical support. Delayed right ventricular assist device (RVAD) support after LVAD implantation is associated with poorer outcomes. With the advent of miniaturized, durable, continuous flow ventricular assist device systems, chronic RVAD and biventricular assist device (BiVAD) support has been used with some success. The purpose of this study was to assess combined BiVAD and LVAD with delayed RVAD support within a four-elemental mock circulatory loop (MCL) simulating the human cardiovascular system. Our hypothesis was that delayed continuous flow RVAD (RVAD) would produce similar hemodynamic and flow parameters to those of initial BiVAD support. Using the MCL, baseline biventricular heart failure with elevated right and left filling pressures with low cardiac output was simulated. The addition of LVAD within a biventricular configuration improved cardiac output somewhat, but was associated with persistent right heart failure with elevated right-sided filling pressures. The addition of an RVAD significantly improved LVAD outputs and returned filling pressures to normal throughout the circulation. In conclusion, RVAD support successfully restored hemodynamics and flow parameters of biventricular failure supported with isolated LVAD with persistent elevated right atrial pressure.

Role of Echocardiography in the Management of Patients with a Biventricular Ventricular Assist Device

Role of Echocardiography in the Management of Patients with a Biventricular Ventricular Assist Device

Surgical Treatment of Mediastinitis with Omentoplasty in Ventricular Assist Device Patients: Report of Referral Center Experience.

Mediastinitis is more frequent in patients with implantable ventricular assist devices (VADs) than in other cardiac surgery patients and carries significant mortality. We report our experience with a stepwise approach including aggressive debridement, jet lavage, vacuum assisted closure dressing, and finally coverage with well-vascularized and immune-active omental flaps in VAD patients with infective mediastinitis. We retrospectively collected and analyzed data of patients with continuous flow VAD who underwent plasty with the omental flap because of mediastinitis at Deutsches Herzzentrum Berlin between January 1, 2008 and October 30, 2015. Eight hundred forty-five patients underwent VAD implantation during the study period. Omentoplasty due to infective mediastinitis was performed in 17 cases. Nine had a HeartWare HVAD as left ventricular assist device (LVAD), three patients had two Heart-Ware HVAD as biventricular assist device (BIVAD), four had a HeartMate II LVAD device, and one patient had a Berlin Heart Incor LVAD. The microorganisms most frequently isolated from the sternal wound were Gram-positive Staphylococcus spp. Four cases of bleeding requiring surgical revision were recorded: three of intraabdominal and one of wound bleeding. Eight patients (47%) survived, whereas the other nine patients (53%) died. Sixteen (94%) required intensive care unit admission, and median hospital stay was 21 (1-182) days. Postoperative renal failure requiring dialysis and septic shock requiring vasopressors were associated with hospital mortality (p = 0.009 and p = 0.05, respectively). Early surgical treatment of mediastinitis after VAD implantation with omentoplasty is a valuable strategy in an otherwise dead-end situation. Bleeding should be meticulously controlled in these anticoagulated and fragile patients.

Long-term use of low-molecular-weight heparin in a patient with Heartware BIVAD (HVAD) with underlying sustained ventricular fibrillation

We report the case of a 59-year-old patient with Heartware (Framingham, MA, USA) biventricular assist device (BIVAD) implantation who had long-term sustained ventricular fibrillation and was managed on low-molecular-weight heparin for up to two years without any adverse events. The successful outcome in this case provides a clue that the long-term management of Heartware BIVADs with low-molecular-weight heparins could be a viable option even in patients with underlying malignant arrhythmias.<Learning objective: Long-term management of Heartware biventricular assist devices (BIVADs) using low-molecular-weight heparin is possible. This treatment strategy can serve as an alternative to oral anticoagulants in a select group of patients. This case report also suggests that BIVADs can potentially serve as a useful alternative to total artificial heart.>

HeartWare HVAD for Biventricular Support in Children and Adolescents: The Stanford Experience.

Despite increasing use of mechanical circulatory support in children, experience with biventricular device implantation remains limited. We describe our experience using the HeartWare HVAD to provide biventricular support to three patients and compare these patients with five patients supported with HeartWare left ventricular assist device (LVAD). At the end of the study period, all three biventricular assist device (BiVAD) patients had been transplanted and were alive. LVAD patients were out of bed and ambulating a median of 10.5 days postimplantation. The BiVAD patients were out of bed a median of 31 days postimplantation. Pediatric patients with both left ventricular and biventricular heart failure can be successfully bridged to transplantation with the HeartWare HVAD. Rapid improvement in functional status following HVAD implantation for isolated left ventricular support is seen. Patients supported with BiVAD also demonstrate functional recovery, albeit more modestly. In the absence of infection, systemic inflammatory response raises concern for inadequate support.

Suspected Malignant Hyperthermia During Biventricular Assist Device Implantation in a Patient With Left Ventricular Noncompaction Cardiomyopathy

Suspected Malignant Hyperthermia During Biventricular Assist Device Implantation in a Patient With Left Ventricular Noncompaction Cardiomyopathy

A simplified state-space model of biventricular assist device-cardiovascular system interaction.

A simplified state-space model of biventricular assist device (BiVAD)-cardiovascular system (CVS) interaction is presented. The state-space equations includes a six-compartments CVS model incorporating the ventricles, the pulmonary and systemic circulations as well as the non-linear behavior of the valve flow, together with a left ventricular assist device (LVAD) and a right ventricular assist device (RVAD) component. The left and right pump speeds serve as the input variables for the state-space model. The model is simulated with three operational modes, i.e. (i) RVAD speed <; LVAD speed, (ii) same LVAD and RVAD speeds and (iii) inclusion of a 6 mm restriction at the right outflow cannula. The effect of RVAD speed variation on the steady state hemodynamics is also studied with and without an outflow banding restriction. Our simulated results are validated with experimental data obtained from clinical, in vivo and in vitro studies provided in the literatures. We observed that despite its simplicity, the model is able to reproduce the observed trends in the reported studies, thus making it feasible for the development of robust yet practical control algorithms.

Mechanical support for biventricular failure using the HeartWare (HVAD) pump

The limited availability of organs for transplant has vastly popularized implantation of left ventricular assist devices. Right ventricular failure is a continued problem with an incidence as high as 44 %, significantly decreasing survival after left ventricular assist devices (LVAD) implantation. Survival is significantly better when LVAD patients at high risk for right ventricular failure (RVF) are converted directly to biventricular assist device (BiVAD) therapy instead of LVAD with subsequent right ventricular assist device (RVAD) implantation. The options available for biventricular assistance entail a total artificial heart (TAH) or additional right-sided placement of a continuous flow/pulsatile device which could be para-corporeal or implantable. The HeartWare HVAD (HeartWare International, Framingham, MA) device in a biventricular configuration is a very attractive option. This report details experiences and techniques for implantation of the HVAD in such a configuration.

(1063) - How Can We Predict Bi-Ventricular Assist Device Requirement?

(1063) - How Can We Predict Bi-Ventricular Assist Device Requirement?

Using inhaled nitric oxide for a patient with pulmonary hypertension during biventricular assist device surgery in the operating room

Many patients experience hemodynamic collapse associated with severe heart failure despite receiving an optimal medical therapy. Therefore, mechanical circulatory assist devices, such as the intra-aortic balloon pump (IABP), extracorporeal membrane oxygenation (ECMO) device, and ventricular assist device (VAD), are used. In this paper, we report the successful treatment of a 59-year-old male patient with heart failure awaiting heart transplantation. Medication therapy, IABP, and ECMO failed to stabilize his advanced heart failure; therefore, he was suggested to undergo biventricular assist device (BiVAD) implantation surgery as a “bridge” to transplantation. However, the blood flow generated by the VAD was inadequate due to elevated pulmonary artery pressure during surgery. Therefore, we used inhaled nitric oxide to treat pulmonary hypertension and to successfully increase the pulmonary blood flow during BiVAD-implantation surgery.