Transient Performance Analysis of Centrifugal Left Ventricular Assist Devices Coupled With Windkessel Model: Large Eddy Simulations Study on Continuous and Pulsatile Flow Operation.

Computational fluid dynamics (CFD) simulations are widely used to develop and analyze blood-contacting medical devices such as left ventricular assist devices (LVADs). This work presents an analysis of the transient behavior of two centrifugal LVADs with different designs: HeartWare VAD and HeartMate3. A scale-resolving methodology is followed through Large Eddy Simulations, which allows for the visualization of turbulent structures. The three-dimensional (3D) LVAD models are coupled to a zero-dimensional (0D) 2-element Windkessel model, which accounts for the vascular resistance and compliance of the arterial system downstream of the device. Furthermore, both continuous- and pulsatile-flow operation modes are analyzed. For the pulsatile conditions, the artificial pulse of HeartMate3 is imposed, leading to a larger variation of performance variables in HeartWare VAD than in HeartMate3. Moreover, CFD results of pulsatile-flow simulations are compared to those obtained by accessing the quasi-steady maps of the pumps. The quasi-steady approach is a predictive tool used to provide a preliminary approximation of the pulsatile evolution of flow rate, pressure head, and power, by only imposing a speed pulse and vascular parameters. This preliminary quasi-steady solution can be useful for deciding the characteristics of the pulsatile speed law before running a transient CFD simulation, as the former entails a significant reduction in computational cost in comparison to the latter.

Intracorporeal LVAD implantation in pediatric patients: A single-center 10 years' experience.

BACKGROUND: Mechanical cardiac support is currently an effective strategy to reduce morbidity and mortality in pediatric patients. However, solid evidence regarding the feasibility of intracorporeal devices in children still needs to be provided. We report our 10-year experience with intracorporeal left ventricular assist devices (LVAD) in children. MATERIALS AND METHODS: We included all patients undergoing intracorporeal, continuous-flow LVAD implantation between 2012 and 2022. Baseline and postoperative data were collected from the institutional database. RESULTS: Seven HeartWare and 4 HeartMate3 were implanted in 11 patients (median age 13.9 years, median body surface area - BSA - 1.42 m2, IQR 1.06-1.68). The most frequent indication to LVAD implant was dilated cardiomyopathy (72.7%). All candidates underwent a thorough preoperative advanced imaging. Three-dimensional reconstructions and implant fit simulation were performed when BSA was <1.2 m2, weight <30 kg, or internal transverse thoracic diameter <20 cm. There was no operative death. The most common postoperative complication was surgical re-exploration due to bleeding (27.3%). One patient died of severe neurological complications after about 3 months of hospitalization. No late deaths or unplanned re-hospitalizations occurred in the remaining 10, 6 of whom were discharged home. There were no major complications at the follow-up. All survivors underwent successful heart transplantation. CONCLUSIONS: Intracorporeal LVAD implantation proved to be a potentially feasible and safe option in young teenagers and children whose BSA was >1.0 m2. In borderline cases, the 3D reconstruction with implant fit simulation can effectively help to identify those patients who can safely undergo intrathoracic LVAD implantation.

Use of Intracorporeal Durable LVAD Support in Children Using HVAD or HeartMate 3-A EUROMACS Analysis.

Purpose: The withdrawal of HVAD in 2021 created a concern for the pediatric population. The alternative implantable centrifugal blood pump HeartMate 3 has since been used more frequently in children. This paper analyses the outcome of children on LVAD support provided with an HVAD or HM3. Methods: A retrospective analysis of the EUROMACS database on children supported with VAD < 19 years of age from 1 January 2009 to 1 December 2021 was conducted. All patients with an LVAD and either an HVAD or HM3 were included. Patients with missing data on VAD status and/or missing baseline and/or follow up information were excluded. Kaplan-Meier survival analysis was performed to evaluate survival differences. Analyses were performed using Fisher's exact test. Results: The study included 150 implantations in 142 patients with 128 implants using an HVAD compared to 28 implants using an HM3. Nine patients (6%) needed temporary right ventricular mechanical support, which was significantly higher in the HM3 group, with 25% (p: 0.01). Patients in the HVAD group were significantly younger (12.7 vs. 14.5 years, p: 0.01), weighed less (45.7 vs. 60 kg, p: <0.000) and had lower BSA values (1.3 vs. 1.6 m2, p: <0.000). Median support time was 204 days. Overall, 98 patients (69%) were discharged and sent home, while 87% were discharged in group HM3 (p: ns). A total of 123 children (86%) survived to transplantation, recovery or are ongoing, without differences between groups. In the HVAD group, 10 patients (8%) died while on support, whereas in 12% of HM3 patients died (p: 0.7). Conclusions: Survival in children implanted with an HM3 was excellent. Almost 90% were discharged and sent home on the device.

Intermacs quarterly report analysis to monitor longitudinal outcomes in a centrifugal flow assist device.

In June 2021, HVAD System distribution ceased due to observational data demonstrating increased mortality and neurological events compared to another commercial device, and a device malfunction with delay or failure to restart, especially in certain subpopulations. To assess ongoing risk for patients on support following subsequent device recalls, the manufacturer's Intermacs HVAD System 2022 Quarterly Reports were queried to identify mortality and adverse events trends in a contemporary cohort of 3110 primary HVAD implantations since October 2017, stratified by year-of-implant. Mean duration of support was 21 ± 16 months, with 33% alive on original device, 25% transplanted, 6% undergoing device exchange, 4% recovered, and 32% expired. Kaplan-Meier and event-per-patient-year estimates for survival, freedom from device explant, stroke, and pump thrombus were similar across year-of-implant. Following market withdrawal and recent device recalls, there appears to be no increase in mortality, stroke, pump thrombus, or explant for HVAD-supported patients. Quarterly report monitoring is ongoing.

Endovascular stenting of an HVAD™ outflow graft pseudoaneurysm that exerts compression and kinking stenosis on the soft portion of the prosthesis.

Key Clinical Message: Complex presentations of MCS patients may necessitate a multidisciplinary approach involving HF cardiologists, CT surgeons, advanced cardiac imagers, and interventional cardiologists in order to define the optimal management strategy. Abstract: Left ventricle assist devices (LVADs) provide life-sustaining treatment for patients with terminal heart failure, but their intricacy allows for complications. One complication is LVAD outflow graft obstruction due to the graft's intraluminal thrombus or extraluminal compression. It may be treated endovascularly with stenting. We report an endovascular stenting of an outflow tract in HVAD™ (HeartWare Inc.) due to a pseudoaneurysm causing compression and kinking stenosis.

Hemocompatibility and hemodynamic comparison of two centrifugal LVADs: HVAD and HeartMate3.

Mechanical circulatory support using ventricular assist devices is a common technique for treating patients suffering from advanced heart failure. The latest generation of devices is characterized by centrifugal turbopumps which employ magnetic levitation bearings to ensure a gap clearance between moving and static parts. Despite the increasing use of these devices as a destination therapy, several long-term complications still exist regarding their hemocompatibility. The blood damage associated with different pump designs has been investigated profoundly in the literature, while the hemodynamic performance has been hardly considered. This work presents a novel comparison between the two main devices of the latest generation-HVAD and HM3-from both perspectives, hemodynamic performance and blood damage. Computational fluid dynamics simulations are performed to model the considered LVADs, and computational results are compared to experimental measurements of pressure head to validate the model. Enhanced performance and hemocompatibility are detected for HM3 owing to its design incorporating more conventional blades and larger gap clearances.

Recovery of a dilated left ventricle after cessation of cocaine and HVAD™ explantation using a titanium plug.

The ultimate goal in the treatment of end-stage heart failure is the recovery of cardiac function following mechanical assistance of the left ventricle. The HVAD™ pump (HeartWare Inc.) left ventricular assist device (LVAD) can be explanted without resternotomy. This article demonstrates that the use of a custom-made mechanical plug (manufactured by INNOVO Solutions GmbH), which can be inserted into the LVAD's sewing ring, is feasible. This mechanical plug explicitly designed for device explantation is a viable alternative to the current standard of care. This article adopts a less invasive technique to explant the pump. The following case illustrates this technique.

Emergency Department Evaluation and Management of Patients with Left Ventricular Assist Devices.

With the increasing use of left ventricular assist devices (LVADs) as destination therapy in patients with severe left heart failure, emergency physicians are more likely to encounter patients with LVAD in their emergency department (ED). Emergency physicians should have a basic understanding of LVAD mechanics, a specific approach to LVAD patient evaluation, and awareness of the must-not-miss LVAD therapy complications and their management to optimize outcomes in this patient population.

Retrograde washout of prepump LVAD thrombosis in a patient on HeartWare™ support.

The success of the left ventricular assist device (LVAD) as a treatment for terminal left-side heart failure is still restrained by some severe complications associated with mechanical circulatory support. Pump thrombus still affects many patients. It is associated with high morbidity and mortality. The therapeutic options include augmentation of anticoagulation and antiplatelet medication, intravenous or catheter-guided thrombolysis, and pump exchange. Heart transplantation would be a desirable option in this population, but unfortunately, it is only theoretical given the increasing number of LVAD implants and decreasing number of organ donors. A retrograde washout maneuver may be a treatment option in prepump thrombosis in selected patients. Therefore, the decision should be made on an individual basis after balancing the risks and benefits of different treatment approaches. In this context, we report a case of retrograde washout of prepump thrombus in a patient who has been on HeartWare™ support for more than 3 years, with a successful bailout strategy.

Third-generation continuous-flow left ventricular assist devices: a comparative outcome analysis by device type.

AIMS: Continuous-flow left ventricular assist devices (CF-LVADs) have become a standard of care in end-stage heart failure. Limited data exist comparing outcomes of HeartMate3 (HM3) and HeartWare HVAD (HW). We aimed to compare midterm outcomes of these devices. METHODS AND RESULTS: Investigator-initiated retrospective-observational comparative analysis of all patients who underwent primary LVAD implantation of either HM3 or HW at our centre between January 2010 and December 2020. Data were derived from a prospective registry. Primary endpoints were all-cause mortality and heart transplantation. Secondary endpoints included device-related major adverse cardiac and cerebrovascular events, which included major bleeding, major neurological dysfunction (defined as persisting neurological impairment for ≥24 h), device-related major infection (excluding driveline infections), major device malfunctions leading to re-intervention or partial device exchange (pump failure, outflow-graft twist or failure, controller failure, battery failure, patient cable failure, but excluding pump thrombosis), and pump thrombosis. Further secondary endpoints included right heart failure, gastrointestinal bleeding, driveline infections, and surgical re-interventions. The secondary outcomes were analysed not only for the first event but also for recurrent events. The analysis included competing risks analysis and recurrent event regression analysis, with adjustment for confounders age, gender, body mass index (BMI), and Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) level. Out of 106 primary CF-LVAD implantations, 36 (34%) received HM3 and 70 (66%) received HW. Median follow-up was 1.48 years [interquartile range 0.67, 2.41]. HM3 was more often implanted in men (91.7% vs. 72.9%, P = 0.024); patients were older (median 61 years [54, 66.5] vs. 52.5 years [43, 60], P < 0.001), had a higher BMI (median 26.7 kg/m2 [23.4, 29.0] vs. 24.3 kg/m2 [20.7, 27.4], P = 0.013), had more comorbidities, and were more likely targeted for destination therapy (36.1% vs. 14.3%, P = 0.010). Death occurred in 33.3% of HM3 patients, compared with 22.9% of HW patients, P = 0.247 (probability of survival at 4 years, 54.7% vs. 74.1%, P = 0.296). After adjustment for confounders, we observed a significant six-fold risk increase in device malfunctions for HW [hazard ratio (HR) 6.49, 95% confidence interval (CI) [1.89, 22.32], P = 0.003], but no significant differences in pump thrombosis (P = 0.173) or overall survival (P = 0.801). CONCLUSIONS: Comparing midterm outcomes between HM3 and HW for LVAD support from a prospective registry, HW patients had a significantly higher risk of device malfunctions. No significant differences were evident between devices in overall survival and in respect to most outcomes.

Global best practices consensus: Long-term management of patients with hybrid centrifugal flow left ventricular assist device support.

OBJECTIVES: Six months after withdrawal of the HeartWare HVAD System (HVAD; Medtronic) from sale, approximately 4000 patients continue ongoing support with this device. In light of the diminishing experience, this global consensus document summarizes key management recommendations. METHODS: International experts with experience in the management of patients with ongoing HVAD support were invited to summarize key aspects of patient and pump management and highlight differences in the current HeartMate 3 (Abbott Laboratories) ventricular assist device. Clinicians from high-implanting HVAD sites reviewed current literature and reported experience to generate a consensus statement. RESULTS: Specific guidelines to assist in the management of ongoing HVAD patients are developed. Key management protocols and helpful techniques developed from experienced clinicians are combined into a short guideline document. As experience with HeartMate 3 increases, key differences in approach to management are highlighted, where appropriate. CONCLUSIONS: With decreasing worldwide experience in the ongoing management of HVAD-supported patients, this consensus guideline provides a summary of best practice techniques from international centers. Differences in HeartMate 3 management are highlighted.

HVAD to HeartMate 3 left ventricular assist device exchange: Best practices recommendations.

The HeartWare HVAD System (Medtronic) is a durable implantable left ventricular assist device that has been implanted in approximately 20,000 patients worldwide for bridge to transplant and destination therapy indications. In December 2020, Medtronic issued an Urgent Medical Device Communication informing clinicians of a critical device malfunction in which the HVAD may experience a delay or failure to restart after elective or accidental discontinuation of pump operation. Moreover, evolving retrospective comparative effectiveness studies of patients supported with the HVAD demonstrated a significantly higher risk of stroke and all-cause mortality when compared with a newer generation of a commercially available durable left ventricular assist device. Considering the totality of this new information on HVAD performance and the availability of an alternate commercially available device, Medtronic halted the sale and distribution of the HVAD System in June 2021. The decision to remove the HVAD from commercial distribution now requires the use of the HeartMate 3 left ventricular assist system (Abbott, Inc) if a patient previously implanted with an HVAD requires a pump exchange. The goal of this document is to review important differences in the design of the HVAD and HeartMate 3 that are relevant to the medical management of patients supported with these devices, and to assess the technical aspects of an HVAD-to-HeartMate 3 exchange. This document provides the best available evidence that supports best practices.

HVAD to HeartMate 3 left ventricular assist device exchange: Best practices recommendations.

The HeartWare HVAD System (Medtronic) is a durable implantable left ventricular assist device that has been implanted in approximately 20,000 patients worldwide for bridge to transplant and destination therapy indications. In December 2020, Medtronic issued an Urgent Medical Device Communication informing clinicians of a critical device malfunction in which the HVAD may experience a delay or failure to restart after elective or accidental discontinuation of pump operation. Moreover, evolving retrospective comparative effectiveness studies of patients supported with the HVAD demonstrated a significantly higher risk of stroke and all-cause mortality when compared with a newer generation of a commercially available durable left ventricular assist device. Considering the totality of this new information on HVAD performance and the availability of an alternate commercially available device, Medtronic halted the sale and distribution of the HVAD System in June 2021. The decision to remove the HVAD from commercial distribution now requires the use of the HeartMate 3 left ventricular assist system (Abbott, Inc) if a patient previously implanted with an HVAD requires a pump exchange. The goal of this document is to review important differences in the design of the HVAD and HeartMate 3 that are relevant to the medical management of patients supported with these devices, and to assess the technical aspects of an HVAD-to-HeartMate 3 exchange. This document provides the best available evidence that supports best practices. (J Thorac Cardiovasc Surg 2022;-:1-8).

Early detection of HVAD pump thrombosis based on technical analysis and power consumption measurements.

BACKGROUND: Continuous-flow left ventricular assist devices (LVADs) have been extensively used in a strategy of bridge to orthotopic heart transplant and destination therapy. The usage of LVAD, however, is not free from limitations such as device-related adverse events, including pump thrombosis (PT). We aimed to develop an algorithm of early PT detection based on the maintenance parameters monitored by the implanted device. METHODS: We analyzed log files of 101 patients implanted with HeartWare pump (HVAD) with 18 PT events among them. For signal processing, we used the open-high-low-close format transformation and typical price (TP) technical analysis indicator. Model parameters were tuned with 5-fold cross-validation, and the final performance was measured on a separate group of patients. RESULTS: Our algorithm achieved 100% sensitivity and 100% specificity of indications. In the final evaluation, alarms preceded the clinical acknowledgement of events by 2 days and 20 h on average. In the worst-case scenario, an alarm was raised 1 day and 8 h prior to the event. CONCLUSIONS: The proposed algorithm could be installed to work directly with the device controller and provide clinicians with automatic readings analysis, raising an alarm when there is a high probability of thromboembolism. Early event detection could enable better thrombosis management and improve prognosis in patients implanted with HVAD.

HVAD versus heartmate III bridge to heart transplantation: Waitlist and posttransplant outcomes.

BACKGROUND: This study compared outcomes of patients bridged with either the Heartware HVAD or Heartmate 3 (HM3) device to orthotopic heart transplantation (OHT). METHODS: The United Network of Organ Sharing registry was queried to perform two separate analyses of adult, isolated OHT candidates bridged with HVAD or HM3. First, waitlist outcomes were compared among patients waitlisted 1/1/2015-3/20/2020. Second, posttransplant survival was compared among those transplanted 1/1/2015-3/20/2020. RESULTS: Two thousand two hundred fifty-five candidates were waitlisted within the study period, 1587 (70.4%) bridged with HVAD and 668 (29.6%) with HM3. At 1 year from waitlisting, cumulative incidence of OHT higher in the HVAD cohort (p < .001). During the same time period, 2643 patients underwent OHT, 2154 (81.5%) with prior HVAD and 489 (18.5%) with HM3. Yearly proportions of patients bridged with HM3 increased across the study period and decreased for HVAD (p < .001). HM3-bridged recipients had shorter waitlist times, longer graft cold ischemic times, and experienced a higher rate of posttransplant dialysis requirement. Unadjusted and risk-adjusted posttransplant mortality rates were similar between both groups. CONCLUSIONS: Posttransplant survival is equivalent regardless of device type used for bridging. However, HM3 patients had lower likelihood of reaching transplantation, which may be a reflection of the recent heart allocation policy changes.

Platelet activation and aggregation in different centrifugal-flow left ventricular assist devices.

Left-ventricular assist devices (LVADs) improve outcomes in end-stage heart failure patients. Two centrifugal-flow LVAD systems are currently approved, HeartMate 3 (HM3) and Medtronic/Heartware HVAD (HVAD). Clinical findings suggest differences in thrombogenicity between both systems. We compared markers of platelet activation and aggregation between HM3 and HVAD. We prospectively included 59 LVAD patients (40 HM3, 19 HVAD). Platelet P-selectin expression, activated glycoprotein (GP) IIb/IIIa and monocyte-platelet aggregates (MPA) were assessed by flow-cytometry. Platelet aggregation was measured by light-transmission aggregometry (LTA) and multiple-electrode aggregometry (MEA). Von-Willebrand factor (VWF) antigen (VWF:Ag), VWF activity (VWF:Ac), and VWF multimer pattern analysis were determined. Soluble P-selectin (sP-selectin) was measured with an enzyme-linked immunoassay. P-selectin, GPIIb/IIIa and MPA levels in vivo and in response to arachidonic acid, adenosine diphosphate, and thrombin receptor activating peptide were similar between HM3 and HVAD (all p > .05). Likewise, agonist-inducible platelet aggregation by LTA and MEA did not differ between HM3 and HVAD (all p > .05). VWF:Ag levels and FVIII:C were similar between both systems (both p > .05), but patients with HVAD had significantly lower VWF:Ac (p = .011) and reduced large VWF multimers (p = .013). Finally, sP-selectin levels were similar in patients with HVAD and HM3 (p = .845). In conclusion, on-treatment platelet activation and aggregation are similar in HM3 and HVAD patients. Potential clinical implications of observed differences in VWF profiles between both LVAD systems need to be addressed in future clinical trials.

Complex HeartWare left ventricular assist device infection treated with pump exchange: clinical alert for the driveline location.

Infection is a major complication in patients with a left ventricular assist device (LVAD). Once a driveline exit-site infection (DLI) reaches the LVAD component, LVAD exchange may become necessary for radical treatment, although clinical results are not satisfactory. In this report, we describe two cases of LVAD infection successfully treated with pump exchange. During LVAD support, the DLI extended into the pump pocket and the outflow graft despite aggressive surgical debridement and negative pressure wound therapy. These two patients required LVAD exchange for radical treatment, because the estimated waiting period for heart transplantation was at least more than 1 year. The LVAD exchange was performed through median re-sternotomy, and the infected HeartWare ventricular assist device (HVAD) was completely removed under cardiopulmonary bypass. Then, a new LVAD covered with the omentum flap was implanted. These two patients were successfully bridged to heart transplantation after 10 months and 2 years of support without recurrence of infection. These two cases may suggest that the driveline of the HVAD needs to be kept away from the outflow graft to prevent refractory outflow graft infection.

Cardiac recovery following left ventricular assist device therapy: experience of complete device explantation including ventricular patch plasty.

OBJECTIVES: Myocardial recovery is a rare phenomenon in left ventricular assist device (LVAD) therapy. Surgical LVAD removal is associated with the risk of cardiac failure, and the individual evaluation of sufficient myocardial recovery is crucial. Thus, complete device explantation is not consistently performed to minimize perioperative risk. However, the remaining ventricular assist device components bear significant risks of infection or thrombosis. Therefore, we developed this study to evaluate a complete LVAD explantation protocol. METHODS: All patients in our institution who had an LVAD explanted were enrolled in the study. Explant surgery involved removal of the driveline, pump housing, sewing ring and outflow graft. The ventricular wall was reconstructed by double patch plasty. Our analysis focused on surgical and postoperative outcome parameters, including all-cause mortality and major adverse cardiac and cerebrovascular events. RESULTS: A total of 12 patients (HVAD, n = 5; HeartMate II, n = 3; HeartMate 3, n = 4) had myocardial recovery and qualified for our LVAD explantation study protocol [median age: 40 years, interquartile range (IQR) 33-52 years; 50% men]. Primary heart failure aetiology: myocarditis (n = 5), dilated cardiomyopathy (n = 4), toxic cardiomyopathy (n = 2) and valvular heart failure (n = 1). The median average duration on LVAD was 10 months (25-75%: IQR 8.5-30 months). The median left ventricular ejection fraction was 15% (IQR 13-18%) at LVAD implantation and 50% (IQR 45-50%) before LVAD explantation (P = 0.0025).The 30-day survival was 100%. The 1-year survival was 91.7%. All patients were discharged after a median 13 days (IQR 10-18 days) postoperatively. No patient had major adverse cardiac and cerebrovascular events. The New York Heart Association functional class remained consistent during the follow-up period (median New York Heart Association functional class: II, IQR II-II class) including preservation of ventricular function. CONCLUSIONS: Complete LVAD explantation with ventricular patch plasty is feasible and has consistent long-term results.