Surgical Correction of Left Ventricular Assist Device Outflow Graft Obstruction Caused by a Wrapped Expanded Polytetrafluoroethylene Graft: A Case Report

A 70-year-old man with dilated cardiomyopathy underwent left ventricular assist device (LVAD) implantation, using a HeartWare ventricular assist device, as a bridge to candidacy. After 26 months, computed tomography (CT) angiography indicated stenosis in the LVAD outflow graft; however, the patient was asymptomatic, prompting a decision to manage his condition with close monitoring. Ten months later, the patient presented with dizziness and low-flow alerts. Subsequent CT angiography revealed a critical obstruction involving the entire LVAD outflow graft. The patient underwent emergency surgery, during which an organized seroma causing the graft obstruction was found between a wrapped expanded polytetrafluoroethylene (ePTFE) graft and a Dacron outflow graft. The covering of the outflow graft was removed, along with the organized seroma. Following removal of the ePTFE wrap and decompression of the outflow graft, normal LVAD flow was reestablished. The practice of wrapping the outflow graft with synthetic material, commonly done to facilitate later redo sternotomy, may pose a risk for outflow graft obstruction.

Use of a surgically implanted, nondischargeable, extracorporeal continuous flow circulatory support system as a bridge to heart transplant

INTRODUCTION AND OBJECTIVES

We aimed to describe the clinical outcomes of the use of the CentriMag acute circulatory support system as a bridge to emergency heart transplantation (HTx).

METHODS

We conducted a descriptive analysis of the clinical outcomes of consecutive HTx candidates included in a multicenter retrospective registry who were treated with the CentriMag device, configured either for left ventricular support (LVS) or biventricular support (BVS). All patients were listed for high-priority HTx. The study assessed the period 2010 to 2020 and involved 16 transplant centers around Spain. We excluded patients treated with isolated right ventricular support or venoarterial extracorporeal membrane oxygenation without LVS. The primary endpoint was 1-year post-HTx survival.

RESULTS

The study population comprised 213 emergency HTx candidates bridged on CentriMag LVS and 145 on CentriMag BVS. Overall, 303 (84.6%) patients received a transplant and 53 (14.8%) died without having an organ donor during the index hospitalization. Median time on the device was 15 days, with 66 (18.6%) patients being supported for> 30 days. One-year posttransplant survival was 77.6%. Univariable and multivariable analyses showed no statistically significant differences in pre- or post-HTx survival in patients managed with BVS vs LVS. Patients managed with BVS had higher rates of bleeding, need for transfusion, hemolysis and renal failure than patients managed with LVS, while the latter group showed a higher incidence of ischemic stroke.

CONCLUSIONS

In a setting of candidate prioritization with short waiting list times, bridging to HTx with the CentriMag system was feasible and resulted in acceptable on-support and posttransplant outcomes.

Nighttime sleep and daytime sleepiness patterns among left ventricular assist device patients

Despite the high prevalence of sleep disturbance in the heart failure population, information about its consequence on daytime function in patients with left-ventricular assist devices (LVADs) is limited. This study examined the nighttime and daytime sleep patterns and changes from pre-implant to 6 months post-implant. This study included 32 LVAD patients. Demographics, nighttime and daytime sleep variables were collected pre-implant and at 1, 3, and 6 months post-implant. Wrist actigraphy and self-report questionnaires measured objective and subjective sleep, respectively. Objective nighttime sleep data were sleep efficiency (SE), sleep latency (SL), total sleep time (TST), wake after sleep onset (WASO), and sleep fragmentation (SF). Objective daytime sleep data were nap times. Self-reported Subjective Sleep Quality Scale (SSQS) and Stanford Sleepiness Scale (SSS) were subjective measures. Increased SF and WASO scores and decreased TST and SE scores were found pre-LVAD implant, indicative of poor sleep quality. TST, SE, naptime and SSQS scores were higher at 3 and 6 months post-implant compared to baseline. Decreases in TST and SF scores were observed at 3 and 6 months post-implant along with increases in SSS scores. Increasing SSS scores and decreasing overall scores from pre- and up to 6 months post-implant suggest improvement in daytime function. This study provides information on sleep-daytime function in the LVAD patient population. Improvements in daytime sleepiness do not imply "good" sleep quality, consistent with the extant knowledge in LVAD literature. Future investigations should elucidate the mechanism by which sleep-daytime function influences quality of life.

Multi-indicator analysis of mechanical blood damage with five clinical ventricular assist devices

PURPOSE

Device-induced blood damage contributes the hemolysis, thrombosis and bleeding complications in patients supported with ventricular assist device (VAD). This study aims to use a multi-indicator method to understand how devices causes blood damage and identify the "hot spots" of blood trauma within VADs.

METHODS

Computational fluid dynamics (CFD) methods were chosen to investigate the hemodynamic features of five clinical VADs (Impella 5.0, UltraMag, CHVAD, HVAD, and HeartMate II) under the same clinical support condition (flow rate of 4.5L/min, pressure head around 75 mmHg). A comprehensive multi-indicator evaluation method including hemodynamic parameters, hemolysis model, thrombotic potential model and bleeding probability model was used to analyze blood damage and assess the hemodynamic performance and hemocompatibility of these VADs.

RESULTS

Simulation results show that shear stress from 50 Pa to 100 Pa plays a major role in blood damage in Impella 5.0, UltraMag and CHVAD, while blood damage in HVAD and HeartMate II is mainly caused by shear stress greater than 100 Pa. Residence time was not the main factor for blood damage in Impella 5.0, and also makes a limited contribution to blood trauma in UltraMag and CHVAD, while it takes a critical role in elevating thrombotic potential in HVAD and HeartMate II. The distribution of regions of high hemolysis risk and high bleeding probability was similar for all these VADs and partially overlapped for high thrombotic potential regions. For Impella 5.0, regions with high hemolysis and bleeding risk were found mainly in the blade tip clearance and diffuser domains, high thrombotic potential regions were almost absent. For UltraMag, regions with high hemolysis, bleeding and thrombosis potential were found in two corners of the inlet pipe, the secondary flow passage, and the impeller eye. For CHVAD, the high-risk regions for hemolysis, bleeding and thrombosis are mainly in the inner side of the secondary flow passage and the middle region of the impeller passage. The narrow hydrodynamic clearance and impeller passage had a high risk of hemolysis and bleeding, and the clearance between the rotor and guide cone and the hydrodynamic clearance had high thrombotic potential. For HeartMate II, regions of high hemolysis risk and bleeding probability were found in the near-wall region of the straightener, the blade tip clearance and the diffuser domain. The corners of the inlet and outlet pipe and the straightener and diffuser regions had high thrombotic potential.

CONCLUSION

The risk of hemolysis, bleeding and thrombosis for these five VADs, in increasing order, was Impella 5.0, UltraMag, CHVAD, HVAD, and HeartMate II. Flow losses caused by the rotor mechanical movement, chaotic flow and narrow clearances increase the blood damage for all these VADs. The multi-indicator analysis can comprehensively evaluate the VAD performance with improved assessment accuracy of CFD.

Decreased Risk of Strokes in Children with Ventricular Assist Devices Within ACTION

We sought to characterize strokes in children with ventricular assist devices. Of 407 patients in the ACTION registry (4/1/18-5/3/2021), 45 (11%) experienced 52 strokes (45 ischemic and 7 hemorrhagic). Median time to stroke was 23.5 days and 19/52 (37%) occurred ≤ 10 days. Stroke rate was 0.09 and 0.63 strokes per patient-year for implantable continuous and paracorporeal devices, respectively. Patients with stroke were younger, more likely to have congenital heart disease and have been on extracorporeal membrane oxygenation at time of VAD. Based on these data, ACTION is now focused on decreasing strokes in these higher-risk patients with particular attention to the peri-implant period.

Derivation and validation of the bridge to transplantation with left ventricular assist device score for 1 year mortality after heart transplantation. The BTT-LVAD score

BACKGROUND

To derive and validate a risk score that accurately predicts 1-year mortality after heart transplantation (HT) in patients bridged to transplant (BTT) with a left ventricular assist device (LVAD).

METHODS

The UNOS database was queried to identify patients BTT with an LVAD between 2008 and 2018. Patients with ⩾1-year follow up were randomly divided into derivation (70%) and validation (30%) cohorts. The primary endpoint was 1-year mortality. A simple additive risk score was developed based on the odds of 1-year mortality after HT. Risk groups were created, and survival was estimated and compared.

RESULTS

A total of 7759 patients were randomly assigned to derivation (n = 5431) and validation (n = 2328) cohorts. One-year post-transplant mortality was 9.8% (n = 760). A 33-point scoring was created from six recipient variables and two donor variables. Risk groups were classified as low (0-5), intermediate (6-10), and high (>10). In the validation cohort, the predicted 1-year mortality was significantly higher in the high-risk group than the intermediate and low-risk groups, 14.7% versus 9% versus 6.1% respectively (log-rank test: p < 0.0001).

CONCLUSION

The BTT-LVAD Score can serve as a clinical decision tool to guide therapeutic decisions in advanced heart failure patients.

Ventricular assist devices in transposition and failing systemic right ventricle: role of tricuspid valve replacement

OBJECTIVES

Ventricular assist device (VAD) for systemic right ventricular (RV) failure patients post-atrial switch, for transposition of the great arteries (TGA), and those with congenitally corrected TGA has proven useful to reduce transpulmonary gradient and bridge-to-transplantation. The purpose of this study is to describe our experience of VAD in systemic RV failure and our move towards concomitant tricuspid valve replacement (TVR).

METHODS

This is a single-centre retrospective study of consecutive adult patients receiving HeartWare VAD for systemic RV failure between 2010 and 2019. From 2017, concomitant TVR was performed routinely. Demographic, clinical variables and echocardiographic and haemodynamic measurements pre- and post-VAD implantation were recorded. Complications on support, heart transplantation and survival rates were described.

RESULTS

Eighteen patients underwent VAD implantation. Moderate or severe systemic tricuspid regurgitation was present in 83.3% of patients, and subpulmonic left ventricular impairment in 88.9%. One-year survival was 72.2%. VAD implantation was technically feasible and successful in all but one. Post-VAD, transpulmonary gradient fell from 16 (15-22) to 10 (7-13) mmHg (P = 0.01). Patients with TVR (n = 6) also demonstrated a reduction in mean pulmonary and wedge pressures. Furthermore, subpulmonic left ventricular end-diastolic dimension (44.3 vs 39.6 mm; P = 0.03) and function improved in this group. After 1 year of support, 72.2% of patients were suitable for transplantation.

CONCLUSIONS

VAD is an effective strategy as bridge-to-candidacy and bridge-to-transplantation in patients with end-stage systemic RV failure. Concomitant TVR at the time of implant is associated with better early haemodynamic and echocardiographic results post-VAD.

Balancing normalcy and safety: health-related needs in patients with a ventricular assist device within their home environment

AIMS

Ventricular assist device (VAD) implantation has become a well-established treatment strategy for patients suffering from advanced heart failure. Ventricular assist device treatment attempts to ameliorate the symptom burden but may create new challenges in patients' lives. Lacking are insights into perceived challenges and health-related needs of patients with VAD within their home environment. Our study aimed to explore the perceived health-related needs of patients living with a VAD in their home environment.

METHODS AND RESULTS

We used a qualitative approach based on a hermeneutic, directed content analysis design. Telephone-based interviews were conducted with 10 patients with VAD from a single cardiology centre in Germany. Data collection and analyses were carried out using content-structuring content analyses. Normalcy and safety were identified as overarching themes: participants expressed a need to balance daily activities between striving for normalcy and maintaining safety. Underlying necessities reflecting this balance were categorized as functional, social, and mental health-related needs. Learning by doing, social-, and peer support were described as relevant requisites. Fulfilling these health-related needs could aid patients living with VAD in achieving the sense of normalcy and safety they seek.

CONCLUSION

Balancing health-related needs with striving for normalcy and safety, emerged as a new core concept for patients with VAD. Thus, being cognizant of this balance when caring for these patients, could facilitate coping after VAD implantation through increasing acceptance of limitations to daily functions by enhancing individual safety. A supportive social environment, including peer support, becomes vital in self-management programs preparing patients with VAD for their home environment.

Non-Surgical Resolution of Inflow Cannula Obstruction of a Left Ventricular Assist Device: A Case Report

A 55-year-old woman who had received an implantable left ventricular assist device 3 months earlier presented with dyspnea and a low-flow alarm of the device. Computed tomography and log-file analysis of the device system suggested inflow cannula obstruction. Since the patient had cardiogenic shock due to pump failure, venoarterial extracorporeal membrane oxygenation (ECMO) was initiated. With ECMO, surgical exchange of the pump was considered. However, the obstruction spontaneously resolved without surgical intervention. It turned out that an obstructive thrombus was washed out by rebooting the pump. Moreover, the thrombus was embolized in the patient’s left subclavian artery. The patient underwent heart transplantation 4 months after the pump obstruction accident and continued to do well.

Ventricular assist devices in paediatric cardiomyopathy and congenital heart disease: An analysis of the German National Register for Congenital Heart Defects

BACKGROUND

Ventricular assist devices (VAD) are increasingly used in patients with end-stage heart failure due to acquired heart disease. Limited data exists on the use and outcome of this technology in children.

METHODS

All children (<18 years of age) with VAD support included in the German National Register for Congenital Heart Defects were identified and data on demographics, underlying cardiac defect, previous surgery, associated conditions, type of procedure, complications and outcome were collected.

RESULTS

Overall, 64 patients (median age 2.1 years; 45.3% female) receiving a VAD between 1999 and 2015 at 8 German centres were included in the analysis. The underlying diagnosis was congenital heart disease (CHD) in 25 and cardiomyopathy in 39 children. The number of reported VAD implantations increased from 13 in the time period 2000-2004 to 27 implantations in the time period 2010-2014. During a median duration of VAD support of 54 days, 28.1% of patients experienced bleeding complications (6.3% intracerebral bleeding), 14.1% thrombotic (10.9% VAD thrombosis) and 23.4% thromboembolic complications (including cerebral infarction in 18.8% of patients). Children with cardiomyopathy were more likely to receive a cardiac transplantation (79.5% vs. 28.0%) compared to CHD patients. Survival of cardiomyopathy patients was significantly better compared to the CHD cohort (p < 0.0001). Multivariate Cox-proportional analysis revealed a diagnosis of CHD (hazard ratio [HR] 4.04, p = 0.001), age at VAD implantation (HR 1.09/year, p = 0.04) and the need for pre-VAD extracorporeal membrane oxygenation (ECMO) support (HR 3.23, p = 0.03) as independent predictors of mortality.

CONCLUSIONS

The uptake of VAD therapy in children is increasing. Morbidity and mortality remain high, especially in patients with congenital heart disease and those requiring ECMO before VAD implantation.

The effect of paracorporeal pulsatile biventricular assist devices on allosensitization in adults: A comparison with left ventricular assist devices

Ventricular assist devices (VADs) have been associated with the development of anti-HLA antibodies ('allosensitization'), but data on devices providing biventricular support in adults are limited. We sought to characterize differences in anti-HLA antibody formation in adult patients receiving left- (LVAD) versus biventricular- (BiVAD) assist devices as bridge to transplantation (BTT) by retrospectively reviewing the records of adult patients who have undergone VAD implantation at our institution. We assessed 82 patients supported with a pulsatile-flow paracorporeal BiVAD and compared them with 40 patients receiving LVAD till 2018. Forty-eight (58.5%) of the BiVAD and 23 (57.5%) of the LVAD patients were eventually transplanted (p = 0.91) with an average time to transplantation 559 and 598 days, respectively (p = 0.73). Evidence of sensitization pre-VAD was found in 11.0% of the BiVAD patients and 15.0% of the LVAD ones (p = 0.53); these percentages rose to 43.9% (p < 0.001) and 40.0% (p = 0.01), respectively. The post-VAD sensitization status was not significantly different between the BiVAD and the LVAD group (p = 0.68). De novo sensitization was comparable between the two groups (p = 0.55). Post-transplantation outcomes regarding rejections and cardiac allograft vasculopathy were also similar. Conclusively, BiVAD- and LVAD- induced allosensitization do not appear to differ significantly.

Patient names for mechanical circulatory support devices: Developing emotional insights

BACKGROUND

Patients with mechanical circulatory support devices regularly experience positive and negative emotions which are reinforced through interactions with their device. We explored emotional relationships between patients and their MCS devices through the names they assign to those devices.

OBJECTIVES

We sought to characterise device naming and suggest future developments which might capitalise on the naming phenomenon to improve patient wellbeing.

METHODS

Qualitative online ethnography extracted comments on device names and emotions from a social media group. Thematic analysis grouped the comments according to their explicit or implied emotions, and their potential consequences for designing future MCS treatment.

RESULTS

Thematic analysis identified 28 codes to characterise the names, from which we inferred 4 main themes for proposed emotional relationships. They centred on humour, coping, improving acceptance for family and friends, and reclaiming agency.

CONCLUSION

We suggest that by deliberately considering these factors in future research and development, clinicians and device manufacturers have scope to improve patient wellbeing.

A pilot clinical trial of a self-management intervention in patients with a left ventricular assist device

Self-management is a health behavior known to predict treatment outcomes in patients with multiple co-morbidities and/or chronic conditions. However, the self-management process and outcomes in the left-ventricular assist device (LVAD) population are understudied. This pilot randomized control trial (RCT) evaluated the feasibility of a novel "smartphone app-directed and nurse-supported self-management intervention" in patients implanted with durable LVADs. Assessments included behavioral (self-efficacy and adherence), clinical (complications), and healthcare utilization (unplanned clinic, emergency room (ER) visits, and re-hospitalization) outcomes, completed at baseline (pre-hospital discharge) and months 1, 3, and 6 post-hospital discharge. Intervention patients (n = 14) had favorable patterns/trends of results across study outcomes than control patients (n = 16). Notably, intervention patients had much lower complications and healthcare utilization rates than controls. For example, intervention patients had 2 (14.3%) driveline infections in 6 months while control patients had 3 (19.0%). Additionally, at month 3, intervention patients had 0% ER visits versus 36% of control patients. At month 6, the mean cumulative number of re-hospitalizations for the control group was higher (0.9 ± 0.93) than intervention (0.3 ± 0.61) group. Despite the small sample size and limitations of feasibility/pilot studies, our outcomes data appeared to favor the novel intervention. Lessons learned from this study suggest the intervention should be implemented for 6 months post-hospital discharge. Further research is needed including large and rigorous multi-center RCTs to generate knowledge explaining the mechanism of the effect of self-management on LVAD treatment outcomes.

Validated Guidelines for Simulating Centrifugal Blood Pumps

PURPOSE

Rotary blood pumps (RBPs) employed as ventricular assist devices are developed to support the ventricles of patients suffering from heart failure. Computational Fluid Dynamics (CFD) is frequently used to predict the performance and haemocompatibility of these pumps during development, however different simulation techniques employed by various research groups result in inconsistent predictions. This inconsistency is further compounded by the lack of standardised model validation, thus it is difficult to determine which simulation techniques are accurate. To address these problems, the US Food and Drug Administration (FDA) proposed a simplified centrifugal RBP benchmark model. The aim of this paper was to determine simulation settings capable of producing accurate predictions using the published FDA results for validation.

METHODS

This paper considers several studies to investigate the impact of simulation options on the prediction of pressure and flow velocities. These included evaluation of the mesh density and interface position through steady simulations as well as time step size and turbulence models (k-ε realizable, k-ω SST, k-ω SST Intermittency, RSM ω-based, SAS and SBES) using a sliding mesh approach.

RESULTS

The most accurate steady simulation using the k-ω turbulence model predicted the pressure to within 5% of experimental results, however experienced issues with unphysical velocity fields. A more computationally expensive transient simulation that used the Stress-Blended Eddy Simulation (SBES) turbulence model provided a more accurate prediction of the velocity field and pressure rise to within experimental variation.

CONCLUSION

The findings of the study strongly suggest that SBES can be used to better predict RBP performance in the early development phase.

Management of a mechanical aortic valve during left ventricular assist device implantation in a previously replaced aortic root

The use of left ventricular assist device (LVAD) in patients with mechanical aortic valves may result in thromboembolic events due to blood stasis around the valve and intermittent valve opening. Mechanical aortic valves encountered during LVAD implantation are managed by replacement with a tissue valve, or closure of the valve with a patch. Closure of the valve carries the risk of sudden death in cases of LVAD stoppage. Replacing the whole mechanical valve conduit is time consuming and carries a significant risk of bleeding and right ventricular (RV) failure. We describe an alternative technique of replacing a mechanical aortic valve by breaking its inner leaflets and sewing a tissue valve on top of the mechanical valve ring.

An introduction to mechanical circulatory support in cardiac intensive care

While use of mechanical circulatory support is increasing, knowledge of its fundamental role and limitations remains poorly understood by many medical professionals. This article summarises the main types of mechanical circulatory support and how they work, particularly focusing on the key information medical professionals should know should they encounter them in hospital. Mechanical circulatory support can be an effective treatment modality in selected pathologies, including myocardial ischaemia, pulmonary congestion, massive pulmonary embolic disease, postcardiotomy cardiogenic shock with failure to wean off bypass, right ventricular failure, bridge to heart and lung transplant and, increasingly, extracorporeal cardiopulmonary resuscitation. Intra-aortic balloon pumps increase coronary perfusion and reduce myocardial oxygen demand in a variety of cardiac conditions. Extracorporeal membrane oxygenation can provide both respiratory and circulatory support to patients. Ventricular assist devices can provide support for not only patients with acute cardiogenic shock, but also for ambulant patients in the community setting.

Bariatric Surgery in Patients with Obesity and Ventricular Assist Devices Considered for Heart Transplantation: Systematic Review and Individual Participant Data Meta-analysis

BACKGROUND

Class II obesity (body mass index BMI ≥35 kg/m²) is a contraindication to heart transplantation (HT). Although few single-center studies (case reports/series and small cohorts) have reported promising outcomes of bariatric surgery (BS) in patients with obesity and ventricular assist devices, low sample sizes have made their analysis and interpretation challenging.

METHODS AND RESULTS

We conducted a systematic search in ClinicalTrials.gov, Cochrane, Embase, PubMed, Google Scholar, and most relevant bariatric and heart failure journals. We extracted baseline and outcome individual participant data for every ventricular assist device patient undergoing BS with reported postoperative BMI and their respective timepoints when BMI data were measured. Fourteen references with 29 patients were included. The mean age was 41.9 ± 12.2 years, 82.8% underwent laparoscopic sleeve gastrectomy, and 39.3% had reported perioperative adverse events. The mean pre-BS BMI was 45.5 ± 6.6 kg/m² and decreased significantly during follow-up (rho -0.671; P< .00001). Among 23 patients with documented listing status, 78.3% were listed for HT. Thirteen of 28 patients (46.4%) underwent HT at 14.4 ± 7.0 months. There were no reported deaths for the HT-free 1-year period. Median follow-up was 24 months (interquartile range, 12-30 months). Twenty-two of 28 patients (78.6%) achieved the composite outcome (BMI of<35 kg/m²/HT/listing for HT/myocardial recovery) at 11 months (interquartile range, 3-17 months). Patients with a BMI<45 kg/m² had a higher chance of achieving the composite outcome (P< .003).

CONCLUSIONS

BS may help patients with obesity and ventricular assist devices to lose a significant amount of weight and improve their candidacy for HT or even achieve myocardial recovery.

MitraClip implantation followed by insertion of a left ventricular assist device in patients with advanced heart failure

Aims

Mitral valve regurgitation (MR) is common in patients with advanced heart failure (HF). Percutaneous mitral valve repair (PMVR) via MitraClip (MC) has emerged as a feasible treatment strategy for these high‐risk patients. However, as HF often further progresses, there is a frequent need for left ventricular assist device (LVAD) implantation in these patients. We aimed to investigate whether prior MC implantation affects the subsequent LVAD implantation and outcome.

Methods and results

Thirty‐seven patients with advanced HF and significant MR who underwent LVAD implantation were retrospectively analysed. Follow‐up data were collected at 1 year after LVAD implantation. Primary endpoint was all‐cause mortality. Secondary endpoint included peri‐operative parameters and clinical development depicted as New York Heart Association (NYHA) class and Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) level. Seventeen patients initially received a MC device (MC group), resulting in a significant reduction in MR grade. After MC, NYHA class and INTERMACS level further worsened, leading to subsequent LVAD implantation after a median time of 475 days in the MC group. At LVAD implantation, overall characteristics were comparable with those of the patients undergoing LVAD implantation without prior MC placement (no‐MC group). Procedural data revealed a higher incidence of right ventricular (RV) failure needing mechanical RV assistance and a longer need for nitric oxide ventilation in the MC group after LVAD implantation. One‐year survival was slightly better in the no‐MC group compared with the MC group [41% (n = 7/17) vs. 65% (n = 13/20); P = 0.15], albeit event‐free survival was comparable between both groups, MC and no‐MC.

Conclusions

LVAD implantation after MC is feasible and safe. However, in patients with advanced HF and severe MR, PMVR may only delay a needed LVAD implantation and thereby lead to poorer peri‐operative RV function and impaired outcome. Arguably, these patients might benefit from the timely management of advanced HF by the means of early LVAD implantation or heart transplantation.

Laparoscopic sleeve gastrectomy in obese patients with ventricular assist devices: a data note

OBJECTIVES

Patients with end-stage heart failure (ESHF) treated with ventricular assist devices (VADs) tend to gain weight after implantation, which is associated with higher complication rates and is a contraindication for heart transplantation (HT). The objective was to analyze the outcomes of obese patients with ESHF and VADs who underwent laparoscopic sleeve gastrectomy (LSG) at Ochsner Medical Center in New Orleans, which is the only program performing VADs and HT in the State of Louisiana, and also one of the largest VAD centers in the USA.

DATA DESCRIPTION

This dataset contains detailed baseline, perioperative, and long-term data of patients with VADs undergoing LSG. These variables were collected retrospectively from electronic medical records. Patients who achieved ≥ 50% excess BMI loss, BMI ≤ 35 kg/m2, listing for HT, HT, or myocardial recovery were identified and the timing to each of these milestones was documented. These data can be used alone or in combination with other datasets to achieve a larger sample size with more power for further analysis of these variables, which include the most important, standard, and objective bariatric and ESHF outcomes of patients with VADs undergoing LSG. Elaboration of composite outcomes is feasible.

Laparoscopic Sleeve Gastrectomy in Patients with Obesity and Ventricular Assist Devices: a Comprehensive Outcome Analysis

We analyzed in detail the outcomes of eight patients with ventricular assist devices (VADs) and obesity who underwent laparoscopic sleeve gastrectomy (LSG) at a single heart transplant (HT) center. This comprehensive analysis included body mass index (BMI) trends from VAD implantation to the time of LSG; BMI and percentage of excess BMI lost during follow-up; adverse outcomes; and changes in echocardiographic parameters, fasting lipids, unplanned hospitalizations, and functional status. We also identified the patients who achieved the following outcomes: listing for HT, HT, 50% excess BMI loss, and BMI < 35 kg/m². Laparoscopic sleeve gastrectomy seems to be a reasonable and effective intervention to help patients with VADs and obesity to decrease excess BMI and become candidates for HT.

Bariatric surgery in obese patients with ventricular assist devices

OBJECTIVES

Patients with end-stage heart failure (ESHF) treated with ventricular assist devices (VADs) tend to gain weight, which may prevent them from receiving heart transplantation (HT) if their body mass index (BMI) reaches ≥ 35 kg/m2. The objective was to synthesize all cases available in the literature and describe the most important outcomes of bariatric surgery (BS) in VAD patients, including BMI trends, reaching a BMI < 35 kg/m2, listing for HT, achieving HT, myocardial recovery, and mortality. These data were obtained for an individual participant data (IPD) meta-analysis and include available IPD for every case in the scientific literature describing VAD patients undergoing BS during VAD support with documented postoperative BMI (and time of measurement) during follow-up.

DATA DESCRIPTION

These data include baseline, periprocedural, and long-term outcomes for the 29 patients meeting selection criteria. The composite outcome includes reaching a BMI < 35 kg/m2, listing for HT, receiving HT, and myocardial recovery, indicating significant BMI loss associated with major ESHF outcomes. As multiple centers are becoming more experienced in this field, the present data can be merged with their databases to form larger samples that will allow to perform further statistical analysis to identify outcome predictors and improve clinical protocols and outcomes.

Extracorporeal life support to ventricular assist device: potential benefits of sternal-sparing approach

Background

Advancements in left ventricular assist device (LVAD) technology have improved long-term survival for properly selected patients with advanced heart failure. However, the subset of patients in critical cardiogenic shock remain difficult to treat with persistently high patient morbidity and mortality. The goal of this study is to describe our institutional experience utilizing extracorporeal membrane oxygenation (ECMO) as a bridge to LVAD for patients in cardiogenic shock comparing the less invasive complete sternal-sparing (CSS) surgical technique to median sternotomy.

Methods

Data was collected as a single center retrospective review of patients implanted with a continuous-flow LVAD directly off ECMO from 2012 to 2018. Patients were stratified by LVAD surgical technique. The primary outcome was survival to discharge. Secondary outcomes included postoperative complications, resource utilization and survival at 6-months.

Results

Of the 37 patients implanted directly off ECMO, 26 (70%) patients were implanted via median sternotomy and 11 (30%) patients by the CSS approach. Median time on ECMO support was 8 days (range, 2-29 days). Preoperative characteristics were similar between groups. Survival to discharge was 78% overall (73% vs. 91% CSS, P=0.391). The CSS cohort had fewer postoperative complications, including fewer transfusions (P=0.044) and trend towards less right ventricular (RV) failure (62% vs. 27% CSS, P=0.079). Both cohorts required similar median length of stay (LOS) in the intensive care unit (ICU) (11 vs. 12 days, P=0.695) and similar overall hospital LOS (34 vs. 22 days, P=0.242). Overall survival was 74% at six months (68% vs. 89% CSS, P=0.386).

Conclusions

VA ECMO can be used effectively as a bridge-to-LVAD for patients in cardiogenic shock. The less invasive CSS approach demonstrates potential advantages to median sternotomy. Further study is needed to better understand the benefits of less invasive surgical techniques.

Exercise-induced hypoxemia predicts heart failure hospitalization and death in patients supported with left ventricular assist devices

Following implantation of continuous-flow left ventricular assist devices, mechanical off-loading results in improved resting hemodynamics; however, peak exercise capacity generally does not increase substantially. This study evaluated patients supported by continuous-flow left ventricular assist devices who were invasively monitored during exercise to define parameters that underpin exercise capacity and outcomes. A review of all patients supported by continuous-flow left ventricular assist devices who underwent supine bicycle ergometry exercise testing with measurement of pulmonary gas exchange during right heart catheterization for evaluation of dyspnea at one institution between 2007 and 2018 was performed (n = 22). The primary outcome of this investigation was death or heart failure hospitalization. Although resting filling pressures were relatively preserved, resting cardiac index (Fick) was low (2.1 ± 0.5 mL/kg/min). An impaired cardiac output reserve was present in 75% of patients. On univariate modeling, patients with supine exercise-induced hypoxemia (O₂ saturation <90%) experienced significantly diminished hospitalization-free survival (unadjusted hazard ratio = 11.0, confidence interval = 2.4-57.2, p = 0.003), which persisted despite adjustment for right heart catheterization peak VO₂ and peak cardiac output (adjusted hazard ratio = 25, confidence interval = 3.6-322, p = 0.001). Our findings suggest that supine exercise testing provides additional prognostic utility in the continuous-flow left ventricular assist device population.

A Quality Bundle to Support High-Risk Pediatric Ventricular Assist Device Implantation

Pediatric ventricular assist device (VAD) implantation outcomes are increasingly promising for children with dilated cardiomyopathy and advanced decompensated heart failure (ADHF). VAD placement in patients with clinical features such as complex congenital cardiac anatomy, small body size, or major comorbidities remains problematic. These comorbidities have been traditionally prohibitive for VAD consideration leaving these children as a treatment-orphaned population. Here we describe the quality bundle surrounding these patients with ADHF considered high risk for VAD implantation at our institution. Over a 7-year period, a quality bundle aimed at the peri-operative care for children with high-risk features undergoing VAD implantation was incrementally implemented at a tertiary children's hospital. Patients were considered high risk if they were neonates (< 30 days), had single-ventricle physiology, non-dilated cardiomyopathy, biventricular dysfunction, or significant comorbidities. The quality improvement bundle evolved to include (1) structured team-based peri-operative evaluation, (2) weekly VAD rounds addressing post-operative device performance, (3) standardized anticoagulation strategies, and (4) a multidisciplinary system for management challenges. These measures aimed to improve communication, standardize management, allow for ongoing process improvement, and incorporate principles of a high-reliability organization. Between January 2010 and December 2017, 98 patients underwent VAD implantation, 48 (49%) of which had high-risk comorbidities and a resultant cohort survival-to-transplant rate of 65%. We report on the evolution of a quality improvement program to expand the scope of VAD implantation to patients with high-risk clinical profiles. This quality bundle can serve as a template for future large-scale collaborations to improve outcomes in these treatment-orphaned subgroups.

Long-term discontinuation of antithrombotic therapy in patients with HeartMate II continuous-flow left ventricular assist device support

Recurrent bleeding events are a common complication of left ventricular assist devices leading to significant morbidity. Clinicians may be reluctant to discontinue all antithrombotic therapies in this setting because of the risk of thrombotic events. To evaluate the safety of this strategy, we conducted a retrospective review of patients within our institution's left ventricular assist device program from February 2010 to July 2018 who had all antithrombotic therapies discontinued in response to recurrent bleeding events requiring hospitalization. Thrombotic and bleeding outcomes after discontinuation of therapy were assessed and compared. Seven patients out of 87 (8%) were identified and included in this analysis. One patient experienced pump thrombosis in the setting of driveline infection with an overall rate of thrombotic events of 0.08 per-patient-year. Sixteen gastrointestinal bleeding events occurred after discontinuation of antithrombotic therapy (1.35 per-patient-year) compared with 37 prior to discontinuation (4.28 per-patient-year) resulting in a significant reduction (reduction rate = 0.32; 95% confidence interval = [0.17, 0.58]; p < .001). Thrombotic complications were rare among patients with HeartMate II left ventricular assist device support who suffered recurrent bleeding events and in whom antithrombotic therapy was, therefore, discontinued. Gastrointestinal bleeding was significantly reduced in this group; however, angioectasia-related gastrointestinal bleedings remained problematic.

Prolonged mechanical ventilation after left ventricular assist device implantation: risk factors and clinical implications

Aims

Unsuccessful weaning from ventilator after major cardiovascular procedures has been shown to be associated with increased post‐operative morbidity and mortality. Our study aimed to identify predictors and clinical implications of prolonged mechanical ventilation (PMV) after left ventricular assist device (LVAD) implantation.

Methods and results

We analysed the data of patients receiving a continuous‐flow LVAD in our centre from December 2010 to September 2017. PMV was defined by a duration of invasive ventilation of >7 days after LVAD implantation. Multivariable logistic regression analysis was performed for predictors of PMV. Survival was estimated by the Kaplan–Meier method. During the study period, 156 patients received a continuous‐flow LVAD in our centre. Seventeen patients were excluded due to early death (<7 days), and 139 patients were enrolled in the study (mean age: 58 years; male: 84%). The median duration of mechanical ventilation post‐operatively was 94 h (range: 5 to 4192 h). PMV was observed in 43% of patients. Patients on PMV were characterized by a more severe disease state at baseline, compared with the group of early extubation, as reflected by their Interagency Registry for Mechanically Assisted Circulatory Support level (Level 1–3: 72 vs. 49%, P = 0.008). Patients on PMV exhibited higher pulmonary wedge pressures (25 vs. 21 mmHg, P = 0.04), lower estimated glomerular filtration rate (53 vs. 60 mL/min/1.73 m², P = 0.02), lower haemoglobin (10.6 vs. 11.6 g/dL, P = 0.02), and lower platelet counts (189 vs. 240/nL, P = 0.02). Previous sternotomy was more frequent in the PMV group (32 vs. 13%, P = 0.006). Higher rates of preoperative circulatory support (30 vs. 11.4%, P = 0.006), dialysis (31.7 vs. 10.1%, P = 0.001), and invasive ventilation (35 vs. 7.6%, P < 0.001) were reported for the PMV group. Logistic regression analysis revealed that estimated glomerular filtration rate [odds ratio (OR) 0.977, confidence interval (CI) 0.955–0.999, P = 0.038], platelet count (OR 0.994, CI 0.989–0.998, P = 0.008), and previous sternotomy (OR 5.079, CI 1.672–15.427, P = 0.004) were independent predictors of PMV. PMV was accompanied by longer intensive care unit (24 vs. 4 days, P < 0.001) and hospital stay (47 vs. 32 days, P = 0.003). Survival analysis revealed a profound increase in mortality at 180‐day post‐implantation in the PMV group (62 vs. 10%, log‐rank: P < 0.001).

Conclusions

Prolonged mechanical ventilation affects nearly half of patients after LVAD implantation. Previous sternotomy, renal function, and platelet counts are associated with increased risk for PMV. PMV is accompanied by decreased survival at 180‐day post‐implantation and longer hospitalizations.

Early Gastrointestinal Complications From Ventricular Assist Devices is Increased by Non-Pulsatile Flow

BACKGROUND

Measurements of organ flow and perfusion during cardiopulmonary bypass suggest that perfusion of the splanchnic bed can be impaired by non-pulsatile flow. We postulated that non-pulsatile flow from centrifugal ventricular assist devices might also compromise splanchnic blood flow and cause bowel ischaemia especially in the period of circulatory instability early post-implant. The aim of the present studies was to compare the incidence of gastrointestinal (GI) complications in patients having a non-pulsatile device with the incidence in those having a pulsatile device.

METHODS

In a pilot study, the initial 12 patients who received the Ventrassist (Ventracor, Sydney, NSW, Australia) centrifugal, non-pulsatile device during the period from June 2003 to September 2005 at the Alfred Hospital, Melbourne were compared with 11 patients who received a Thoratec (Thoratec, Pleasanton, CA, USA), pulsatile, positive displacement device and the incidence was recorded of GI complications requiring an intervention either surgical, endoscopic or by interventional radiology. This was followed by a larger (full) study of a second cohort of similar ventricular assist device (VAD) patients from January 1992 until December 2012 comparing 53 patients having non-pulsatile devices and 110 having pulsatile devices.

RESULTS

In the pilot study, the overall incidence of complications in the non-pulsatile group (67%) was almost double that in the pulsatile group (36%) but the difference was not statistically significant (p = 0.15) because of the small number (n = 23) of participants. In the full study, all GI complications with either device occurred within the first 3 weeks post-implant. In the non-pulsatile patients, there was a higher incidence of GI bleeding, 23% vs 4% (p = 0.002), endoscopies, 24% vs 12% (p = 0.049). More patients with a non-pulsatile flow device had delayed absorption of nasogastric feeds than their pulsatile counterparts, 35% vs 7% (p < 0.0001). Patients with a non-pulsatile flow device had a higher overall rate of gastrointestinal complications than patients had with a pulsatile flow device, 56% vs 20% (p < 0.0001). After correcting for the other predictors, the odds of developing a gastrointestinal complication in the pulsatile group was significantly lower (odds ratio 0.07) than in the non-pulsatile device group (p < 0.0001).

CONCLUSIONS

We conclude that the use of non-pulsatile centrifugal VADs compared with pulsatile positive displacement VADs is associated with a higher incidence of both haemorrhagic and ischaemic complications in the gastro-intestinal system especially in the very early post-implant period. Whether these complications could be reduced in centrifugal devices by increasing their pulsatility is not clear and merits further research.

Implementation of Heart Transplantation Program to Advanced Heart Failure Patients in Brazil

PURPOSE

Heart transplantation is the gold standard treatment for advanced heart failure. Left ventricular assist devices (LVADs), despite being a good option for these patients, are not quite available in developing countries. Time spent in heart transplant waiting list has increased lately even in regions where the number of transplants has also risen showing that a new strategy should be sought.

RECENT FINDINGS

Transplant process organization combined with multidisciplinary work are linked to better outcomes while improvement in donor's care and in pre-transplant evaluation might be opportunities to change the long waiting list scenario. For the first time in Brazil, a survey with the most expressive heart transplant centers has been made, which allows an overview of treatment of advanced heart failure in a developing country. We also described a model of heart transplant team, which has proved to be a success when compared to the largest heart transplant centers in Latin America.

Temporary assist device support for the right ventricle: pre-implant and post-implant challenges

Severe right ventricular (RV) failure is more likely reversible than similar magnitudes of left ventricular (LV) failure and, because reversal of both adaptive remodeling and impaired contractility require most often only short periods of support, the use of temporary RV assist devices (t-RVADs) can be a life-saving therapy option for many patients. Although increased experience with t-RVADs and progresses made in the development of safer devices with lower risk for complications has improved both recovery rate of RV function and patient survival, the mortality of t-RVAD recipients can still be high but it depends mainly on the primary cause of RV failure (RVF), the severity of end-organ dysfunction, and the timing of RVAD implantation, and much less on adverse events and complications related to RVAD implantation, support, or removal. Reduced survival of RVAD recipients should therefore not discourage appropriate application of RVADs because their underuse further reduces the chances for RV recovery and patient survival. The article reviews and discusses the challenges related to the pre-implant and post-implant decision-making processes aiming to get best possible therapeutic results. Special attention is focused on pre-implant RV assessment and prediction of RV improvement during mechanical unloading, patient selection for t-RVAD therapy, assessment of unloading-promoted RV recovery, and prediction of its stability after RVAD removal. Particular consideration is also given to prediction of RVF after LVAD implantation which is usually hampered by the complex interactions between the different risk factors related indirectly or directly to the RV potential for reverse remodeling and functional recovery.

[Heart failure: ventricular assist devices and cardiac transplantation : A review of current surgical innovations]

BACKGROUND

End-stage heart failure is one of the leading causes of death in Germany. Cardiac transplantation is still considered the gold standard for the treatment of terminal heart failure; however, there is a discrepancy between patients on the waiting list and yearly performed transplantations. As an alternative, ventricular assist devices have achieved a high level of importance but treatment is still associated with challenges. Novel systems as well as innovative surgical techniques contribute to improving the safety and effectiveness of the treatment.

OBJECTIVE

To generate an overview of current surgical innovations in cardiac transplantation and mechanical circulatory support.

MATERIAL AND METHODS

A Medline search was conducted regarding innovations in cardiac transplantation and mechanical circulatory support.

RESULTS AND CONCLUSION

Not only the number of yearly performed cardiac transplantations has changed but also recipient profiles. While in the pioneering era of transplantation the typical candidate was young, not previously operated on and with lower levels of comorbidities, today's patients are significantly older, have been fitted with ventricular assist devices and have increased operative risk profiles. Modern methods of organ preservation enable longer transportation and operation times as well as an improved assessment of graft function and perspectives for graft optimization in the future. In the area of ventricular assist devices, advances in the reduction of the stroke rate seem to have been achieved by the latest generation devices. From a surgical perspective, less invasive surgical techniques with promising initial results have been established at numerous centers.

Fluid Dynamics in the HeartMate 3: Influence of the Artificial Pulse Feature and Residual Cardiac Pulsation

Ventricular assist devices (VADs), among which the HeartMate 3 (HM3) is the latest clinically approved representative, are often the therapy of choice for patients with end-stage heart failure. Despite advances in the prevention of pump thrombosis, rates of stroke and bleeding remain high. These complications are attributed to the flow field within the VAD, among other factors. One of the HM3's characteristic features is an artificial pulse that changes the rotor speed periodically by 4000 rpm, which is meant to reduce zones of recirculation and stasis. In this study, we investigated the effect of this speed modulation on the flow fields and stresses using high-resolution computational fluid dynamics. To this end, we compared Eulerian and Lagrangian features of the flow fields during constant pump operation, during operation with the artificial pulse feature, and with the effect of the residual native cardiac cycle. We observed good washout in all investigated situations, which may explain the low incidence rates of pump thrombosis. The artificial pulse had no additional benefit on scalar washout performance, but it induced rapid variations in the flow velocity and its gradients. This may be relevant for the removal of deposits in the pump. Overall, we found that viscous stresses in the HM3 were lower than in other current VADs. However, the artificial pulse substantially increased turbulence, and thereby also total stresses, which may contribute to clinically observed issues related to hemocompatibility.

Acquired Von Willebrand syndrome in patients on long-term support with HeartMate II

Objectives

Impaired binding of Von Willebrand factor (VWF) to platelets and to collagen due to acquired Von Willebrand syndrome (AVWS) is associated with support from a ventricular assist device (VAD) and can contribute to bleeding tendencies in patients with VADs. The onset of AVWS has been shown to occur immediately after VAD implantation. Our aim was to determine long-term data on AVWS in VAD patients.

Methods

We analysed 278 data sets of 74 patients on HeartMate II (HMII) support for 3-80 months after implantation (11.2 ± 12.1, median 6.3 months.). Ristocetin cofactor activity (VWF:RCo), collagen binding capacity (VWF:CB), VWF antigen (VWF:Ag) and the ratios of VWF:RCo/VWF:Ag and VWF:CB/VWF:Ag were determined. Further, the presence of high molecular weight (HMW) multimers of VWF was investigated.

Results

Abnormally low values of VWF:RCo/VWF:Ag and VWF:CB/VWF:Ag were found in 69% and 97% of blood samples, respectively. Only ten of 181 multimer analyses showed a normal pattern, and HMW multimers were present in both specimens in only one of the 74 patients. No significant changes in these parameters were observed over time. The VWF:CB/VWF:Ag ratio correlated with the multimer patterns, whereas the VWF:RCo/VWF:Ag ratio seemed to be less sensitive for AVWS.

Conclusions

Our data indicate that AVWS is a typical phenomenon in patients with VAD support and that there are no time-dependent changes in these parameters apparent in most patients on long-term support with HMII.

Progressive spontaneous coronary artery dissection secondary to fibromuscular dysplasia requiring mechanical circulatory support

Spontaneous coronary artery dissection (SCAD) usually appears as an acute coronary syndrome with good prognosis. We present the case of a 39-year-old woman with progressive SCAD secondary to fibromuscular dysplasia with catastrophic course. The patient required several mechanical circulatory support systems including a left ventricular assist device (CentriMag^®, Thoratec, Pleasanton, CA, USA) as bridge to recovery. <Learning objective: The beneficial use of mechanical circulatory support devices as a bridge to recovery or heart transplant in the setting of refractory cardiogenic shock in spontaneous coronary artery dissection.>.

Microfludic platforms for the evaluation of anti-platelet agent efficacy under hyper-shear conditions associated with ventricular assist devices

Thrombus formation is a major adverse event affecting patients implanted with ventricular assist devices (VADs). Despite anti-thrombotic drug administration, thrombotic events remain frequent within the first year post-implantation. Platelet activation (PA) is an essential process underling thrombotic adverse events in VAD systems. Indeed, abnormal shear forces, correlating with specific flow trajectories of VADs, are strong agonists mediating PA. To date, the ability to determine efficacy of anti-platelet (AP) agents under shear stress conditions is limited. Here, we present a novel microfluidic platform designed to replicate shear stress patterns of a clinical VAD, and use it to compare the efficacy of two AP agents in vitro. Gel-filtered platelets were incubated with i) acetylsalicylic acid (ASA) and ii) ticagrelor, at two different concentrations (ASA: 125 and 250 µM; ticagrelor: 250 and 500 nM) and were circulated in the VAD-emulating microfluidic platform using a peristaltic pump. GFP was collected after 4 and 52 repetitions of exposure to the VAD shear pattern and tested for shear-mediated PA. ASA significantly inhibited PA only at 2-fold higher concentration (250 µM) than therapeutic dose (125 µM). The effect of ticagrelor was not dependent on drug concentration, and did not show significant inhibition with respect to untreated control. This study demonstrates the potential use of microfluidic platforms as means of testing platelet responsiveness and AP drug efficacy under complex and realistic VAD-like shear stress conditions.

Novel Use of Thalidomide in Recurrent Gastrointestinal Tract Bleeding in Patients with Left Ventricular Assist Devices: A Case Series

BACKGROUND

Bleeding is an important and common complication of left ventricular assist devices (LVADs). One of the common causes of gastrointestinal bleeding is arteriovenous malformations. However, the source of bleeding is often hard to identify. Thalidomide is efficacious in treatment of gastrointestinal (GI) bleeding in non-LVAD patients. We report our experience of the use of thalidomide in the treatment of GI bleeding in four patients with LVAD.

METHOD AND RESULTS

Four patients who had recurrent GI bleeding from May 2009 to December 2014 were started on thalidomide. All of them responded to treatment and had no further gastrointestinal bleeding while on thalidomide. One patient developed constipation, requiring thalidomide to be stopped. Another patient developed symptomatic neuropathy, that resolved with reduction of dosage.

CONCLUSION

Thalidomide appears safe and efficacious in LVAD patients with recurrent gastrointestinal bleeding.

Pump Speed Waveform Analysis to Detect Aortic Valve Opening in Patients on Ventricular Assist Device Support

As the aortic valve (AV) opens, the pump pressure head remains constant, which is reflected as a "notch/plateau" in pump pressure and flow signals. However, instantaneous flow estimation may be influenced by friction and is particularly difficult in axial pumps. Therefore, a new method to determine the duration of AV opening based on the area under the curve (AUC) of the power spectral density analysis of pump speed signal was developed. Data from patients implanted with HeartWare HVAD left ventricular assist device were studied at different pump speeds, with simultaneous transthoracic echocardiography in two cohorts. In the first group, pump data of 15 patients were used to investigate the ability to discriminate between an open and closed AV. In the second cohort of a further 13 patients, the duration of AV opening was measured from digitized M-mode images, and the relationship between the AV opening time and the new method assessed. In 14 of the initial 15 patients, AV status could be discriminated using only one threshold for all patients. In the second cohort, gradual speed reduction resulted in aortic valve opening in 12 of the 13 patients. The correlation between AV opening duration and AUC was 0.96 ± 0.03. Regression analysis indicated a linear relationship in each of the patients with a small error between the fit and the measured opening time (root mean square error = 11.0 ± 7.6 ms). However, the slopes (69.0 ± 52.8) and intercepts (-31.4 ± 78.0) varied widely between patients. The sensitivity and specificity for the new method using AUC threshold of 0.95 for aortic valve closure was 95% and 91%, respectively. The newly developed method to detect AV opening not only provides information on the AV status during LVAD support (open/closed) but also gives insight into the duration of AV opening. Because the slope of the relationship varies from patient to patient, initial training and adaptation of the method to each patient seems to be required.

Hemodynamic Support Devices for Complex Percutaneous Coronary Intervention

High-risk percutaneous coronary intervention (PCI) encompasses a growing portion of total PCIs performed and typically includes patients with high-risk clinical and anatomic characteristics. Such patients may represent not only a high-risk group for complications but also a group who may derive the most benefit from complete revascularization. Several hemodynamic support devices are available. Trial data, consensus documents, and guidelines currently recommend high-risk PCI aided by hemodynamic support devices, and this article discusses the patient populations who would benefit from such an approach, the available devices and strategies, and expected outcomes.

Aspirin has limited ability to modulate shear-mediated platelet activation associated with elevated shear stress of ventricular assist devices

Continuous flow ventricular assist devices (cfVADs) while effective in advanced heart failure, remain plagued by thrombosis related to abnormal flows and elevated shear stress. To limit cfVAD thrombosis, patients utilize complex anti-thrombotic regimens built upon a foundation of aspirin (ASA). While much data exists on ASA as a modulator of biochemically-mediated platelet activation, limited data exists as to the efficacy of ASA as a means of limiting shear-mediated platelet activation, particularly under elevated shear stress common within cfVADs. We investigated the ability of ASA (20, 25 and 125 μM) to limit shear-mediated platelet activation under conditions of: 1) constant shear stress (30 dynes/cm(2) and 70 dynes/cm(2)); 2) dynamic shear stress, and 3) initial high shear exposure (70 dynes/cm(2)) followed by low shear exposure - i.e. a platelet sensitization protocol, utilizing a hemodynamic shearing device providing uniform shear stress in vitro. The efficacy of ASA to limit platelet activation mediated via passage through a clinical cfVAD system (DeBakey Micromed) in vitro was also studied. ASA reduced platelet activation only under conditions of low shear stress (38% reduction compared to control, n=10, p<0.004), with minimal protection at higher shear stress and under dynamic conditions (n=10, p>0.5) with no limitation of platelet sensitization. ASA had limited ability (25.6% reduction in platelet activation rate) to modulate shear-mediated platelet activation induced via cfVAD passage. These findings, while performed under "deconstructed" non-clinical conditions by utilizing purified platelets alone in vitro, provide a potential contributory mechanistic explanation for the persistent thrombosis rates experienced clinically in cfVAD patients despite ASA therapy. An opportunity exists to develop enhanced pharmacologic strategies to limit shear-mediated platelet activation at elevated shear levels associated with mechanical circulatory support devices.

Microfluidic emulation of mechanical circulatory support device shear-mediated platelet activation

Thrombosis of ventricular assist devices (VADs) compromises their performance, with associated risks of systemic embolization, stroke, pump stop and possible death. Anti-thrombotic (AT) drugs, utilized to limit thrombosis, are largely dosed empirically, with limited testing of their efficacy. Further, such testing, if performed, typically examines efficacy under static conditions, which is not reflective of actual shear-mediated flow. Here we adopted our previously developed Device Thrombogenicity Emulation methodology to design microfluidic platforms able to emulate representative shear stress profiles of mechanical circulatory support (MCS) devices. Our long-term goal is to utilize these systems for point-of-care (POC) personalized testing of AT efficacy under specific, individual shear profiles. First, we designed different types of microfluidic channels able to replicate sample shear stress patterns observed in MCS devices. Second, we explored the flexibility of microfluidic technology in generating dynamic shear stress profiles by modulating the geometrical features of the channels. Finally, we designed microfluidic channel systems able to emulate the shear stress profiles of two commercial VADs. From CFD analyses, the VAD-emulating microfluidic systems were able to replicate the main characteristics of the shear stress waveforms of the macroscale VADs (i.e., shear stress peaks and duration). Our results establish the basis for development of a lab-on-chip POC system able to perform device-specific and patient-specific platelet activation state assays.

Hemodynamic Effects of Ventricular Assist Device Implantation on Norwood, Glenn, and Fontan Circulation: A Simulation Study

The growing population of failing single-ventricle (SV) patients might benefit from ventricular assist device (VAD) support as a bridge to heart transplantation. However, the documented experience is limited to isolated case reports. Considering the complex and different physiopathology of Norwood, Glenn, and Fontan patients and the lack of established experience, the aim of this work is to realize and test a lumped parameter model of the cardiovascular system able to simulate SV hemodynamics and VAD implantation effects to support clinical decision. Hemodynamic and echocardiographic data of 30 SV patients (10 Norwood, 10 Glenn, and 10 Fontan) were retrospectively collected and used to simulate patients' baseline. Then, the effects of VAD implantation were simulated. Simulation results suggest that the implantation of VAD: (i) increases the cardiac output and the mean arterial systemic pressure in all the three palliation conditions (Norwood 77.2 and 19.7%, Glenn 38.6 and 32.2%, and Fontan 17.2 and 14.2%); (ii) decreases the SV external work (Norwood 55%, Glenn 35.6%, and Fontan 41%); (iii) decreases the pressure pulsatility index (Norwood 65.2%, Glenn 81.3%, and Fontan 64.8%); (iv) increases the pulmonary arterial pressure in particular in the Norwood circulation (Norwood 39.7%, Glenn 12.1% and Fontan 3%); and (v) decreases the atrial pressure (Norwood 2%, Glenn 10.6%, and Fontan 8.6%). Finally, the VAD work is lower in the Norwood circulation (30.4 mL·mm Hg) in comparison with Fontan (40.3 mL·mm Hg) and to Glenn (64.5 mL·mm Hg) circulations. The use of VAD in SV physiology could be helpful to bridge patients to heart transplantations by increasing the CO and unloading the SV with a decrement of the atrial pressure and the SV external work. The regulation of the pulmonary flow is challenging because the Pap is increased by the presence of VAD. The hemodynamic changes are different in the different SV palliation step. The use of numerical models could be helpful to support patient and VAD selection to optimize the clinical outcome.

In Vitro Comparison of Active and Passive Physiological Control Systems for Biventricular Assist Devices

The low preload and high afterload sensitivities of rotary ventricular assist devices (VADs) may cause ventricular suction events or venous congestion. This is particularly problematic with rotary biventricular support (BiVAD), where the Starling response is diminished in both ventricles. Therefore, VADs may benefit from physiological control systems to prevent adverse events. This study compares active, passive and combined physiological controllers for rotary BiVAD support with constant speed mode. Systemic (SVR) and pulmonary (PVR) vascular resistance changes and exercise were simulated in a mock circulation loop to evaluate the capacity of each controller to prevent suction and congestion and increase exercise capacity. All controllers prevented suction and congestion at high levels of PVR (900 dynes s cm(-5)) and SVR (3000 dynes s cm(-5)), however these events occurred in constant speed mode. The controllers increased preload sensitivity (0.198-0.34 L min(-1) mmHg(-1)) and reduced afterload sensitivity (0.0001-0.008 L min(-1) mmHg(-1)) of the VADs when compared to constant speed mode (0.091 and 0.072 L min(-1) mmHg(-1) respectively). The active controller increased pump speeds (400-800 rpm) and pump flow by 2.8 L min(-1) during exercise, thus increasing exercise capacity. By reducing suction and congestion and by increasing exercise capacity, the control systems presented in this study may help increase quality of life of VAD patients.

Preliminary report on the cost effectiveness of ventricular assist devices

The aim of the present study was to perform a cost-effectiveness analysis (CEA) of ventricular assist devices (VAD) implantation surgery in the Japanese medical reimbursement system. The study group consisted of thirty-seven patients who had undergone VAD implantation surgery for dilated cardiomyopathy (n = 25; 67.6 %) or hypertrophic cardiomyopathy (n = 4; 10.8 %), and others (n = 8; 21.6 %). Quality-adjusted life years (QALYs) were calculated using the utility score and years of life. Medical reimbursement bills were chosen as cost indices. The observation period was the 12-month period after surgery. Then, the incremental cost-effectiveness ratio was calculated according to the VAD type. In addition, the prognosis after 36 months was estimated on the basis of the results obtained using the Markov chain model. The mean preoperative INTERMACS profile score was 2.35 ± 0.77. Our results showed that the utility score, which indicates the effectiveness of VAD implantation surgery, improved by 0.279 ± 0.188 (ΔQALY, p < 0.05). The cost of VAD implantation surgery was 313,282 ± 25,275 (ΔUS$/year) on the basis of medical reimbursement bills associated with therapeutic interventions. The calculated result of CEA was 364,501 ± 190,599 (ΔUS$/QALY). The improvement in the utility score was greater for implantable versus extracorporeal VADs (0.233 ± 0.534 vs. 0.371 ± 0.238) and ICER was 303,104 (ΔUS$/ΔQALY). Furthermore, when we estimated CEA for 36 months, the expected baseline value was 102,712 (US$/QALY). Therefore, VAD implantation surgery was cost effective considering the disease specificities.

The Right Ventricular Function After Left Ventricular Assist Device (RVF-LVAD) study: rationale and preliminary results

AIMS

Despite improved outcomes and lower right ventricular failure (RVF) rates with continuous-flow left ventricular assist devices (LVADs), RVF still occurs in 20-40% of LVAD recipients and leads to worse clinical and patient-centred outcomes and higher utilization of healthcare resources. Preoperative quantification of RV function with echocardiography has only recently been considered for RVF prediction, and RV mechanics have not been prospectively evaluated.

METHODS AND RESULTS

In this single-centre prospective cohort study, we plan to enroll a total of 120 LVAD candidates to evaluate standard and mechanics-based echocardiographic measures of RV function, obtained within 7 days of planned LVAD surgery, for prediction of (i) RVF within 90 days; (ii) quality of life (QoL) at 90 days; and (iii) RV function recovery at 90 days post-LVAD. Our primary hypothesis is that an RV echocardiographic score will predict RVF with clinically relevant discrimination (C >0.85) and positive and negative predictive values (>80%). Our secondary hypothesis is that the RV score will predict QoL and RV recovery by 90 days. We expect that RV mechanics will provide incremental prognostic information for these outcomes. The preliminary results of an interim analysis are encouraging.

CONCLUSION

The results of this study may help improve LVAD outcomes and reduce resource utilization by facilitating shared decision-making and selection for LVAD implantation, provide insights into RV function recovery, and potentially inform reassessment of LVAD timing in patients at high risk for RVF.

Simulation of Ventricular, Cavo-Pulmonary, and Biventricular Ventricular Assist Devices in Failing Fontan

Considering the lack of donors, ventricular assist devices (VADs) could be an alternative to heart transplantation for failing Fontan patients, in spite of the lack of experience and the complex anatomy and physiopathology of these patients. Considering the high number of variables that play an important role such as type of Fontan failure, type of VAD connection, and setting (right VAD [RVAD], left VAD [LVAD], or biventricular VAD [BIVAD]), a numerical model could be useful to support clinical decisions. The aim of this article is to develop and test a lumped parameter model of the cardiovascular system simulating and comparing the VAD effects on failing Fontan. Hemodynamic and echocardiographic data of 10 Fontan patients were used to simulate the baseline patients' condition using a dedicated lumped parameter model. Starting from the simulated baseline and for each patient, a systolic dysfunction, a diastolic dysfunction, and an increment of the pulmonary vascular resistance were simulated. Then, for each patient and for each pathology, the RVAD, LVAD, and BIVAD implantations were simulated. The model can reproduce patients' baseline well. In the case of systolic dysfunction, the LVAD unloads the single ventricle and increases the cardiac output (CO) (35%) and the arterial systemic pressure (Pas) (25%). With RVAD, a decrement of inferior vena cava pressure (Pvci) (39%) was observed with 34% increment of CO, but an increment of the single ventricle external work (SVEW). With the BIVAD, an increment of Pas (29%) and CO (37%) was observed. In the case of diastolic dysfunction, the LVAD increases CO (42%) and the RVAD decreases the Pvci, while both increase the SVEW. In the case of pulmonary vascular resistance increment, the highest CO (50%) and Pas (28%) increment is obtained with an RVAD with the highest decrement of Pvci (53%) and an increment of the SVEW but with the lowest VAD power consumption. The use of numerical models could be helpful in this innovative field to evaluate the effect of VAD implantation on Fontan patients to support patient and VAD type selection personalizing the assistance.

Development of ventricular assist devices in China: present status, opportunities and challenges

The growing number of heart failure patients and the scarcity of organ donors account for the huge need for the development of mechanical circulatory systems, including ventricular assist devices (VADs) and artificial hearts, in China. Several research programmes on blood pumps have been under way for the last three decades. However, unlike in other countries, the development of VADs has been extremely slow, and no system is currently approved and available for clinical application. There are many reasons for this situation. This article provides an overview of the present development of experimental and clinical research on VADs in China. In addition, the challenges for the clinical development of mechanical circulatory support in China are discussed.