Axial Flow Left Ventricular Assist Devices Research Articles

Machine learning based on computational fluid dynamics enables geometric design optimisation of the NeoVAD blades

The NeoVAD is a proposed paediatric axial-flow Left Ventricular Assist Device (LVAD), small enough to be implanted in infants. The design of the impeller and diffuser blades is important for hydrodynamic performance and haemocompatibility of the pump. This study aimed to optimise the blades for pump efficiency using Computational Fluid Dynamics (CFD), machine learning and global optimisation. Meshing of each design typically included 6 million hexahedral elements and a Shear Stress Transport turbulence model was used to close the Reynolds Averaged Navier–Stokes equations. CFD models of 32 base geometries, operating at 8 flow rates between 0.5 and 4 L/min, were created to match experimental studies. These were validated by comparison of the pressure-flow and efficiency-flow curves with those experimentally measured for all base prototype pumps. A surrogate model was required to allow the optimisation routine to conduct an efficient search; a multi-linear regression, Gaussian Process Regression and a Bayesian Regularised Artificial Neural Network predicted the optimisation objective at design points not explicitly simulated. A Genetic Algorithm was used to search for an optimal design. The optimised design offered a 5.51% increase in efficiency at design point (a 20.9% performance increase) as compared to the best performing pump from the 32 base designs. An optimisation method for the blade design of LVADs has been shown to work for a single objective function and future work will consider multi-objective optimisation.

Five-Year Outcomes in Patients With Fully Magnetically Levitated vs Axial-Flow Left Ventricular Assist Devices in the MOMENTUM 3 Randomized Trial

Although durable left ventricular assist device (LVAD) therapy has emerged as an important treatment option for patients with advanced heart failure refractory to pharmacological support, outcomes, including survival, beyond 2 years remain poorly characterized. To report the composite end point of survival to transplant, recovery, or LVAD support free of debilitating stroke (Modified Rankin Scale score >3) or reoperation to replace the pump 5 years after the implant in participants who received the fully magnetically levitated centrifugal-flow HeartMate 3 or axial-flow HeartMate II LVAD in the MOMENTUM 3 randomized trial and were still receiving LVAD therapy at the 2-year follow-up. This observational study was a 5-year follow-up of the MOMENTUM 3 trial, conducted in 69 US centers, that demonstrated superiority of the centrifugal-flow LVAD to the axial-flow pump with respect to survival to transplant, recovery, or LVAD support free of debilitating stroke or reoperation to replace the pump at 2 years. A total of 295 patients were enrolled between June 2019 to April 2021 in the extended-phase study, with 5-year follow-up completed in September 2021. Of 1020 patients in the investigational device exemption per-protocol population, 536 were still receiving LVAD support at 2 years, of whom 289 received the centrifugal-flow pump and 247 received the axial-flow pump. There were 10 end points evaluated at 5 years in the per-protocol population, including a composite of survival to transplant, recovery, or LVAD support free of debilitating stroke or reoperation to replace the pump between the centrifugal-flow and axial-flow pump groups and overall survival between the 2 groups. A total of 477 patients (295 enrolled and 182 provided limited data) of 536 patients still receiving LVAD support at 2 years contributed to the extended-phase analysis (median age, 62 y; 86 [18%] women). The 5-year Kaplan-Meier estimate of survival to transplant, recovery, or LVAD support free of debilitating stroke or reoperation to replace the pump in the centrifugal-flow vs axial-flow group was 54.0% vs 29.7% (hazard ratio, 0.55 [95% CI, 0.45-0.67]; P < .001). Overall Kaplan-Meier survival was 58.4% in the centrifugal-flow group vs 43.7% in the axial-flow group (hazard ratio, 0.72 [95% CI, 0.58-0.89]; P = .003). Serious adverse events of stroke, bleeding, and pump thrombosis were less frequent in the centrifugal-flow pump group. In this observational follow-up study of patients from the MOMENTUM 3 randomized trial, per-protocol analyses found that receipt of a fully magnetically levitated centrifugal-flow LVAD vs axial-flow LVAD was associated with a better composite outcome and higher likelihood of overall survival at 5 years. These findings support the use of the fully magnetically levitated LVAD. ClinicalTrials.gov Identifier: NCT02224755 and NCT03982979.

Successful Pregnancy with HeartMate 3 (Abbott) Left Ventricular Assist Device

<h3>Introduction</h3> Left ventricular assist devices (LVADs) are an evolving therapy for patients with end-stage heart failure (HF). Due to high maternal and fetal risk from hemodynamic variation and need for anticoagulation, LVADs are a relative contraindication to pregnancy. Successful pregnancies have been observed with axial-flow LVADs as well as the continuous-flow HeartWareTM (Medtronic) LVAD, but the safety of the continuous-flow HeartMate 3TM (HM3) LVAD (Abbott) with pregnancy is unknown. Herein we present a case of a successful delivery in a patient with a HM3 LVAD. <h3>Case Report</h3> A 39-year-old female with peripartum cardiomyopathy underwent HM3 implantation as destination therapy due to severely elevated panel-reactive antibodies. She followed routinely with HF clinic. Two years after implantation, she presented to HF clinic at 15 weeks gestation despite oral birth control. She received counseling on the risk of pregnancy but opted against termination. Spironolactone was discontinued; all other medications (carvedilol, torsemide) were continued. She was anticoagulated with enoxaparin until imaging confirmed that she was no longer in the first trimester and then subsequently resumed warfarin. She underwent transthoracic echocardiogram-guided speed optimization at 20 weeks after her clinical exam demonstrated volume overload. LVAD speed was increased from 5500 to 5700 revolutions per minute. Serial obstetric sonography demonstrated normal fetal anatomy. Fetal echocardiogram and genetic screening were unremarkable. Maternal fetal medicine, anesthesia, and HF cardiology agreed on scheduled cesarean section with bilateral salpingectomy at 34 weeks gestation. At 33 weeks gestation, she switched back to enoxaparin from warfarin with her last dose timed for 24 hours prior to delivery. The patient underwent successful cesarean section with neuraxial anesthesia. During delivery, she was supported with low-dose phenylephrine with return-to-flows in the 80s. A healthy boy was delivered. <h3>Summary</h3> This case supports the notion that HM3 LVADs may provide adequate hemodynamic support during pregnancy and delivery. As previously shown, successful care of patients with LVADs during pregnancy requires a multidisciplinary approach to optimize the health and safety of mother and baby.

De novo human leukocyte antigen allosensitization patterns in patients bridged to heart transplantation using left ventricular assist devices

IntroductionWe examined the impact and time course of de novo human leukocyte antigen (HLA) allosensitization following left ventricular assist device (LVAD) implantation. Methods and resultsForty patients had a calculated panel reactive antibody (cPRA) prior to LVAD surgery between January 2014 and December 2018. Of these patients, we retrospectively studied 33 patients who had pre-LVAD cPRA <10%. De novo allosensitization was defined as cPRA ≥10% within 3 months following LVAD surgery, and “persistent allosensitization” was defined as cPRA ≥10% at time of heart transplant or death. One-third (11/33) of our cohort developed de novo allosensitization within 3-months post-LVAD. Median duration of follow-up during LVAD support was 588 days (IQR 337–1071 days), or approximately 19 months. In an adjusted, multivariable analysis, female sex remained associated with de novo allosensitization (adjusted odds ratio [95%CI]: 11 (1.4–85), P = 0.026). De novo allosensitization was subsequently associated with persistent allosensitization (P = 0.024). Both axial-flow and centrifugal-flow LVADs had similar rates of allosensitization. Compared to those with no allosensitization, patients with de novo allosensitization did not appear to have inferior post-transplant outcomes of death or treated rejection. ConclusionIn our single-center experience, one-third of patients developed de novo allosensitization which did not appear to associate with inferior post-transplant outcomes. Female sex was associated with de novo allosensitization.

A Flow Sensor-Based Suction-Index Control Strategy for Rotary Left Ventricular Assist Devices.

Rotary left ventricular assist devices (LVAD) have emerged as a long-term treatment option for patients with advanced heart failure. LVADs need to maintain sufficient physiological perfusion while avoiding left ventricular myocardial damage due to suction at the LVAD inlet. To achieve these objectives, a control algorithm that utilizes a calculated suction index from measured pump flow (SIMPF) is proposed. This algorithm maintained a reference, user-defined SIMPF value, and was evaluated using an in silico model of the human circulatory system coupled to an axial or mixed flow LVAD with 5–10% uniformly distributed measurement noise added to flow sensors. Efficacy of the SIMPF algorithm was compared to a constant pump speed control strategy currently used clinically, and control algorithms proposed in the literature including differential pump speed control, left ventricular end-diastolic pressure control, mean aortic pressure control, and differential pressure control during (1) rest and exercise states; (2) rapid, eight-fold augmentation of pulmonary vascular resistance for (1); and (3) rapid change in physiologic states between rest and exercise. Maintaining SIMPF simultaneously provided sufficient physiological perfusion and avoided ventricular suction. Performance of the SIMPF algorithm was superior to the compared control strategies for both types of LVAD, demonstrating pump independence of the SIMPF algorithm.

LVAD decommissioning for myocardial recovery: Long-term ventricular remodeling and adverse events

Left ventricular assist devices (LVADs) mechanically unload the heart and coupled with neurohormonal therapy can promote reverse cardiac remodeling and myocardial recovery. Minimally invasive LVAD decommissioning with the device left in place has been reported to be safe over short-term follow-up. Whether device retention reduces long-term safety, or sustainability of recovery is unknown. This is a dual-center retrospective analysis of patients who had achieved responder status (left ventricular ejection fraction, LVEF ≥40% and left ventricular internal diastolic diameter, LVIDd ≤6.0 cm) and underwent elective LVAD decommissioning for myocardial recovery from May 2010 to January 2020. All patients had outflow graft closure and driveline resection with the LVAD left in place. Emergent LVAD decommissioning for an infection or device thrombosis was excluded. Patients were followed with serial echocardiography for up to 3-years. The primary clinical outcome was survival free of heart failure hospitalization, LVAD reimplantation, or transplant. During the study period 515 patients received an LVAD and 29 (5.6%) achieved myocardial recovery, 12 patients underwent total device explantation or urgent device decommissioning, 17 patients underwent elective LVAD decommissioning, and were included in the analysis. Median age of patients at LVAD implantation was 42 years (interquartile range, IQR: 25-54 years), all had a nonischemic cardiomyopathy, and 5 (29%) were female. At LVAD implantation, median LVEF was 10% (IQR: 5%-15%), and LVIDd 6.6 cm (IQR: 5.8-7.1 cm). There were 11 hydrodynamically levitated centrifugal-flow (65%), and 6 axial-flow LVADs (35%). The median duration of LVAD support before decommissioning was 28.7 months (range 13.5-36.2 months). As compared to the turndown study parameters, 1-month post-decommissioning, median LVEF decreased from 55% to 48% (p=0.03), and LVIDd increased from 4.8 cm to 5.2 cm (p=0.10). There was gradual remodeling until 6 months, after which there was no statistical difference on follow-up through 3-years (LVEF 42%, LVIDd 5.6 cm). Recurrent infections affected 41% of patients leading to 3 deaths and 1 complete device explant. Recurrent HF occurred in 1 patient who required a transplant. Probability of survival free of HF, LVAD, or transplant was 94% at 1-year, and 78% at 3-years. LVAD decommissioning for myocardial recovery was associated with excellent long-term survival free from recurrent heart failure and preservation of ventricular size and function up to 3-years. Reducing the risk of recurrent infections, remains an important therapeutic goal for this management strategy.

Acoustic Properties of Axial and Centrifugal Flow Left Ventricular Assist Devices and Prediction of Pump Thrombosis

ObjectiveTo characterize the properties of the audible tones produced by current left ventricular assist device (LVAD) pumps approved for use, and to ascertain if changes in those may be present in the setting of pump thrombosis. Patients and MethodsFrom August 31, 2016, to January 16, 2020, LVAD recipients consented to have surface recordings obtained using a high-fidelity digital stethoscope. Audio data were analyzed using digital recording and editing software to produce an acoustic spectrogram by Fast Fourier transformation. ResultsRecordings were obtained in 53 patient encounters (27 HeartMate II, 19 HeartWare and 7 HeartMate 3). In 12 patients (9 HeartMate II, 3 HeartWare) there was a clinical concern for pump thrombosis. In all patients and pump models, a fundamental frequency was noted, and the second and third harmonics were also clearly detectable. Where thrombosis occurred in the HeartMate II pump, the absolute (normal -46.9 [-57.5,-42.9] dB vs thrombosis -41.4 [-49.8,-26.8] dB; P=.08) and relative (normal 0.72 [0.62, 0.92] vs thrombosis 0.95 [0.86, 1.24]; P=.01) third harmonic frequencies were increased in amplitude. Where paired data were available, an increase in the absolute and relative third harmonic frequencies was observed in all patients. In the case of the HeartWare device, a consistent difference in harmonic amplitudes in the setting of thrombosis could not be identified. ConclusionA consistent pattern of fundamental and harmonic frequencies is common to all LVADs currently approved for use. Alterations in the amplitude of higher order harmonics may signal the onset of pump thrombosis in axial flow LVADs.

"Clipping the Leak" - A Case Series of Transcatheter Mitral Valve Repair after Left Ventricular Assist Device

Introduction Mitral regurgitation (MR) often co-exists with severe left ventricular (LV) systolic dysfunction and there is controversy regarding the need for corrective surgery at the time of left ventricular assist device (LVAD) implantation as it often improves with mechanical LV unloading. We describe three patients with significant MR after LVAD implant in which transcatheter mitral valve repair (TMVR) [MitraClip] was utilized. To our knowledge, this is the largest case series of TMVR post-LVAD implant reported. Case Report Patient #1 is a 40-year-old male with severe LV dysfunction due to a non-ischemic cardiomyopathy (CM) who presented in cardiogenic shock (CS) and underwent centrifugal-flow LVAD [Heartmate 3]. MR was severe due to bileaflet tethering at time of implant and improved to mild to moderate immediately after. With medical and device optimization, EF improved to 35-40% however he had right ventricular (RV) dysfunction with recurrence of severe MR secondary to bileaflet prolapse. Given NYHA III symptoms, he underwent TMVR with improvement in MR to mild to moderate and improvement in his symptoms to NYHA class II. Patient #2 is a 27-year-old female who presented with acute severe LV dysfunction with moderate to severe functional MR due to viral myocarditis. She required extracorporeal membrane oxygenation and initially improved but decompensated after removal of support and subsequently underwent implantation of Heartmate 3. Her LV function recovered and she was scheduled for LVAD explantation but pre-operative tranesophageal echocardiogram revealed moderate to severe MR secondary to bileaflet prolapse so the procedure was deferred. She successfully underwent TMVR with improvement to mild to moderate MR and is planned for LVAD explant in the future. She had unchanged NYHA I symptoms before and after TMVR. Patient #3 is a 76-year-old male who underwent an axial-flow LVAD [Heartmate 2] seven years prior for ischemic CM. He reported worsening dyspnea despite device and medication optimization and was found to have moderate to severe MR (secondary to leaflet tethering). He underwent a successful TMVR with reduction in MR to mild to moderate, as well as improvement of NYHA class III to II. Summary Persistence of MR after LVAD implantation can be associated with worse outcomes. We describe three patients who underwent successful TMVR to reduce morbidity.

Decreased RPM reduces von Willebrand factor degradation with the EVAHEART LVAS: implications for device-specific LVAD management.

Continuous-flow left ventricular assist devices (LVADs) produces supraphysiologic shear stress that causes von Willebrand factor (VWF) degradation and a bleeding diathesis. Reduction of revolutions per minute (RPM) with axial-flow LVADs does not decrease shear stress enough to reduce VWF degradation and bleeding. However, it is unknown if RPM reduction with centrifugal flow LVADs may minimize VWF degradation. We tested the hypothesis that RPM reduction preserves VWF multimers in the centrifugal-flow EVAHEART left ventricular assist system (LVAS), which is designed to minimize shear stress and blood trauma. Whole blood samples were collected from humans (n = 28). Blood was circulated in ex vivo mock circulatory loops for 6 hours with an EVAHEART LVAS at 2300 (n = 12), 2100 (n = 8), or 1800 RPM (n = 8). Immunoblotting was used to resolve and quantify VWF multimers and degradation fragments. RPM reduction from 2300 to 2100 to 1800 RPM significantly decreased EVAHEART blood flow from 5.8 ± 0.4 to 4.3 ± 0.6 to 4.1 ± 0.5 L/min (analysis of variance [ANOVA], P = .03). RPM reduction protected VWF from pathologic degradation. At lower RPMs, significantly greater levels of VWF multimers were observed (ANOVA, P = .001). Similarly, at lower RPMs, significantly fewer VWF fragments, a product of VWF degradation, were observed (ANOVA, P = .007). RPM reduction significantly reduced VWF degradation with the centrifugal-flow EVAHEART LVAS, an LVAD specifically designed with low shear stress. Different LVADs have unique hematologic footprints and should be managed with device-specific protocols. Adjustment of RPM to minimize blood trauma while still maintaining physiologic hemodynamics has the potential to decrease complications related to LVAD-associated von Willebrand's disease, such as gastrointestinal bleeding and hemorrhagic stroke.

Intraventricular Flow Patterns in Patients Treated with Left Ventricular Assist Devices.

The success of left ventricular assist device (LVAD) therapy is hampered by complications such as thrombosis and bleeding. Understanding blood flow interactions between the heart and the LVAD might help optimize treatment and decrease complication rates. We hypothesized that LVADs modify shear stresses and blood transit in the left ventricle (LV) by changing flow patterns and that these changes can be characterized using 2D echo color Doppler velocimetry (echo-CDV). We used echo-CDV and custom postprocessing methods to map blood flow inside the LV in patients with ongoing LVAD support (Heartmate II, N = 7). We compared it to healthy controls (N = 20) and patients with dilated cardiomyopathy (DCM, N = 20). We also analyzed intraventricular flow changes during LVAD ramp tests (baseline ± 400 rpm). LVAD support reversed the increase in blood stasis associated with DCM, but it did not reduce intraventricular shear exposure. Within the narrow range studied, the ventricular flow was mostly insensitive to changes in pump speed. Patients with significant aortic insufficiency showed abnormalities in blood stasis and shear indices. Overall, this study suggests that noninvasive flow imaging could potentially be used in combination with standard clinical methods for adjusting LVAD settings to optimize flow transport and minimize stasis on an individual basis.

Reverse Myocardial Remodeling with Centrifugal versus Axial-Flow Left Ventricular Assist Device in Chronic Heart Failure Patients

Recent studies have shown enhanced survival and reduced morbidity with centrifugal (HeartMate 3-HM3) left ventricular assist device (LVAD) compared with axial-flow (HeartMate II-HMII) LVAD. However, differences in LVAD-induced left ventricular (LV) reverse remodeling between the two devices remain uninvestigated. The aim of our study was to compare the LV structural and functional changes between these two types of mechanical unloading. Echocardiographic parameters of LV structure and function were obtained pre-implant and at 1, 3, 6, and 12 month of LVAD support. Statistical comparison of quantitative data was performed using 2-tailed Wilcoxon signed-rank test for paired samples and categorical data were compared using Fisher's exact test. A total of 32 consecutive patients (median age 62.5 [IQR 52-68] years, 15.6% female) received axial-flow LVAD (HMII) and 31 consecutive patients (median age 58 [IQR 47-71] years, 16.1% female) received centrifugal LVADs (HM3). There were no significant differences in the baseline characteristics between the study groups. Following LVAD support there were no differences in the LV ejection fraction or LV mass index between the two types of mechanical unloading across all time points (figure 1A and 1B). In centrifugal LVAD patients, LV end diastolic volume index was lower at 1 and 3 months and LV end systolic volume index was lower at 1 month. No differences were identified after 3 months of mechanical unloading (figure 1C and 1D). Both centrifugal and axial-flow LVADs resulted in improved LV function and structure. Although LV volumes were found to be lower at 1 and 3 months in centrifugal pump patients, long-term (> 3month) mechanical unloading seem to exert similar effects on LV structural and functional parameters.

Improvement of Hemodynamics in a Left Ventricular Assist Device Using Heuristic Aerodynamic Strategies to Redesign the Bladed Flow Domain

High levels of shear stress in the bladed flow domain of Left Ventricular Assist Devices (LVADs) lead to hemolysis, degradation of the von Willebrand factor and gastrointestinal bleeding. Optimal hemodynamics of the LVAD are crucial to minimizing the probability of these adverse events. In this study, a typical axial flow LVAD was redesigned using aerodynamics-based strategies to improve its hemodynamics and hence clinical outcomes for recipients. A reference LVAD was parametrically modeled using Computer Aided Design software. The baseline hemodynamic performance was then mapped using Computational Fluid Dynamics simulation of the blood flow. Subsequently, various heuristic, aerodynamic tactics were applied to iteratively redesign the flow domain. After each design change, a simulation was run to evaluate the hemodynamics of the LVAD. The ultimate modifications included streamlining the hub and shroud profiles, tuning the blade leading edge incidence angles, and sweeping back the leading edge profile of the blades. The optimized LVAD achieved significant hemodynamic improvements. The peak and area-averaged values of shear stress in the reference LVAD, 2300.43 Pa and 97.44 Pa, were reduced by 65.2% and 44.8%, respectively. At the rated flow of 0.1 kg/s and speed of 7000 rpm, the optimized design developed a slightly higher pressure rise, but within 4.5% of the reference design, in the same geometric envelope. Thus, the reduction in shear stress levels was achieved without compromise on the primary form and function of the LVAD. This study demonstrates that the application of heuristic, intensive aerodynamic design methods can significantly improve the hemodynamics of LVADs. Research suggests that patients implanted with such an optimized device would experience lower rates of hemolysis and gastrointestinal bleeding, as well as reduced degradation of the von Willebrand factor, improving outcomes post-implantation.

Left ventricular assist systems and infection-related outcomes: A comprehensive analysis of the MOMENTUM 3 trial

In a randomized controlled trial (MOMENTUM 3), the HeartMate 3 (HM3) fully magnetically levitated centrifugal-flow left ventricular assist device (LVAD) demonstrated superiority over the HeartMate II (HMII) axial-flow LVAD. These findings were driven by hemocompatibility-related outcomes, but infection-related outcomes were not altered by device choice. In this trial-level analysis, we analyzed the clinical patterns of infection-related outcomes over 2years of support. In MOMENTUM 3, 1,020 patients were implanted with either the HM3 (n = 515) or HMII (n = 505) pump. Clinical characteristics and morbidity- and mortality-related outcomes were evaluated to identify predictors associated with major infectious complications, using univariable and multivariable models. The cumulative number of infections at 2years was 1,213 (634 HM3 and 579 HMII), and major infection occurred in 58% of patients with the HM3 and 56% of patients with the HMII (p = 0.57). Infections of a local nature unrelated to pump components were most common (n = 681/1,213; 56%), followed by driveline-associated infection (n = 329/1,213; 27%), sepsis (n = 194/1,213; 16%), and other events (n = 9/1,213; 0.7%). Bacterial pathogens were implicated in 806 of 1,213 events (66%); significant predictors of infection included sex (women vs men; hazard ratio [HR]: 1.38, p = 0.003), pre-implant use of intra-aortic balloon pump (HR: 1.33, p = 0.02), pre-implant history of cardiac surgery (HR: 1.28, p = 0.01), and body mass index ≥ 30 (HR: 1.40, p < 0.0001). Most deaths in those with infection occurred owing to non-infectious causes. Infection is the most common adverse effect in patients implanted with contemporary continuous-flow LVADs, with most such events unrelated to the pump or its peripheral components. Whether chronic mechanical circulatory devices confer an immunomodulatory effect pre-disposing to infection warrants closer scrutiny to understand and ameliorate this morbidity.

Outcomes based on blood pressure in patients on continuous flow left ventricular assist device support: An Interagency Registry for Mechanically Assisted Circulatory Support analysis

An optimal blood pressure (BP) range to mitigate morbidity and mortality on left ventricular assist device (LVAD) support has not been clearly defined. Average Doppler opening pressure, mean arterial pressure (MAP), and/or systolic blood pressure (SBP) were calculated in operative survivors (n = 16,155) of LVAD support in the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS). BP distributions were used to group patients into low (BP <25th percentile), normal (25-75th percentile), high (75th-95th percentile), and very high (>95th percentile). Associations between BP and adverse events were evaluated using Cox regression (hazard ratio[HR], 95% confidence interval). The median (25th, 75th) MAP, Doppler, and SBP (mm Hg) during continuous flow LVAD support were 84 (77, 90), 85 (80, 92), and 99 (90, 107) mm Hg, respectively. BP had a bimodal risk association with survival. At 3 years, survival was 58% ± 1.8%in those with low MAP (≤75 mmHg) vs 70% ± 0.9%, 71% ± 1.5%, and 63% ± 3.0%in the those with normal, high, or very high average MAP, respectively. Patients with chronically low MAP (≤75 mmHg), Doppler (≤80 mmHg), and SBP (<90 mmHg) had 35%-42% higher adjusted hazards of death than patients with normal or high BP (p ≤ 0.0001). Patients with MAP >100 mmHg, Doppler ≥105 mmHg, and SBP ≥120 mmHg had 17%-20% higher adjusted hazards of death than those with normal pressures (p < 0.05). In patients on axial flow LVADs, elevated SBP (HR 1.08 [95% confidence interval, 1.04-1.13] per 10 mmHg increase) but not MAP correlated with increased incident of stroke. In INTERMACS, BP extremes during LVAD support increase the risk for adverse events, supporting a MAP goal >75 mmHg and <90 mmHg. Hypotension conferred the highest risk for mortality. Excessive BP control should be avoided, and Doppler opening pressure should not be assumed to represent MAP in all patients.

Can we expect improvements in outcomes with centrifugal vs axial flow left ventricular assist devices in patients transitioned from extracorporeal life support?

Several patient-related characteristics have been associated with inferior outcomes following durable left ventricular assist device (LVAD) implantation in patients transitioned from venoarterial extracorporeal membrane oxygenation (VA ECMO). The impact of LVAD pump type used is less well-known. We compared outcomes between patents who received axial and centrifugal flow LVADs following stabilization with VA ECMO. From January 2011 to December 2018, we implanted 28 LVADs in patients transitioned from VA ECMO. This included 17 axial flow devices (HeartMate II LVAD, Abbott Laboratories, Chicago, IL) and 11 centrifugal flow pumps (eight HeartWare HVADs; Medtronic, Minneapolis, MN and three HeartMate 3 LVAS pumps; Abbott Laboratories, Chicago, IL). There was no difference in hospital mortality (23.5% vs 18.2%, P = .74) or 1-year survival (P = .31) between the devices. There were no differences in adverse event rates between the two pump types, apart from a higher rate of gastrointestinal bleeding in patients who received centrifugal flow pumps (1.44 events per 100 patient-months vs 14.67 events per 100 patient-months, P = .010). Preimplantation levels of alanine aminotransferase (hazard ratio [HR], 1.001; 95% confidence interval [CI], 1.000 to 1.002; P = .004) and elevated serum creatinine level (HR, 3.480; 95% CI, 1.121-10.807; P = .031) emerged as significant predictors of decreased 1-year survival. Preimplantation optimization of end-organ function is the single most important determinant of successful post-LVAD survival in patients transitioned from extracorporeal life support. There is no association of pump type with LVAD outcomes up to 1-year post implantation.

Diagnostic Accuracy of FDG PET/CT in Suspected LVAD Infections: A Case Series, Systematic Review, and Meta-Analysis

ObjectivesThe purpose of this study was to describe our experience with fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography computed tomography (PET/CT) in diagnosing left ventricular assist device (LVAD) infections and perform a meta-analysis of published studies to determine overall diagnostic accuracy. BackgroundDevice-related infections are a common complication of LVADs and are linked to worse outcomes. Diagnosis of LVAD infections remains challenging. FDG PET/CT has demonstrated good diagnostic accuracy in several other infectious conditions. MethodsThis was a single-center, retrospective case series of FDG PET/CT scans in suspected LVAD infection between September 2015 and February 2018. A systematic review of PubMed from database inception through March 2018 was also conducted to identify additional studies. ResultsNineteen FDG PET/CT scans were identified for the retrospective case series. The systematic review identified an additional 3 publications, for a total of 4 studies involving 119 scans assessing diagnostic performance. Axial (n = 36) and centrifugal (n = 83) flow LVADs were represented. Pooled sensitivity was 92% (95% confidence interval [CI]: 82% to 97%) and specificity was 83% (95% CI: 24% to 99%) for FDG PET/CT in diagnosing LVAD infections. Summary receiver-operating characteristic curve analysis demonstrated an AUC of 0.94 (95% CI: 0.91 to 0.95). ConclusionsFDG PET/CT for suspected LVAD infections demonstrates good diagnostic accuracy, with overall high sensitivity but variable specificity.

Clinical outcomes of inpatient cardiac rehabilitation for patients with treated left ventricular assist device in Korea: 1-year follow-up.

In Korea, the first patient with a left ventricular assist device (LVAD) for destination therapy had successful implantation of a continuous-flow model in 2012. We investigated the safety and efficacy of exercise therapy with LVAD implantation 15 Korean patients. We retrospectively reviewed 15 patients (mean age, 67.4±11.6 years; 10 males, 5 female, left ventricular ejection fraction 23.6%±7.1%), including 4 with implanted continuous-flow and 11 an axial-flow LVAD. The New York Heart Association functional classification, ejection fraction, and quality of life were obtained. Survival rate, adverse events, admission rates, and enrollment rates in cardiac rehabilitation were investigated. Survival at 6 and 12 months was 100% and 89%, respectively. The New York Heart Association functional classification improved from 3.4±0.5 to 2.3±0.05 at 12 months postoperatively (P<0.0001). The ejection fraction significantly increased from 23.6%±7.2% on the preoperative day to 35.4%±14.2% at 1 year (P<0.0018). The quality of life was also improved at 1 year (P<0.0001). The most common adverse events were bleeding (56%) and dyspnea (44%). The number of admissions was 3.2 per patient-year. LVAD therapy is a safe and effective treatment option with exercise intervention for Korean patients waiting for heart transplantation or those who were ineligible for heart transplantation. A larger study with longer follow-up is needed to determine details clinical outcomes after LVAD.

Contemporary Use of Glycoprotein IIb/IIIa Inhibitors in Patients with Left Ventricular Assist Devices

Purpose The efficacy of glycoprotein IIB/IIIA inhibitor (IIB/IIA) use in patients who receive left ventricular assist devices (LVAD) has not been well studied. A prior single center study of eptifibatide use for pump thrombosis in almost exclusively HeartMate II (HMII) LVAD patients concluded that the risks of such use outweighed the benefits. We sought to analyze the outcomes of IIB/IIIA use in our more contemporary cohort of mixed axial and centrifugal flow LVAD patients. Methods We performed a retrospective analysis of all patients with LVADs implanted at Stanford Hospital from 2010-2018. We used the electronic medical record to identify LVAD patients who received IIB/IIIA inhibitors for suspected pump thrombus. Outcomes assessed included resolution of thrombus, need for pump exchange, and adverse events such as stroke and death. Results Out of 304 patients who had an LVAD placed during the study period, 42 (14%) received IIB/IIIA inhibitors after LVAD placement. Of this subset, 74% were male, 69% received HM II LVADs (31% HeartWare), 71% were implanted as destination therapy, and 88% received eptifibatide (12% tirofiban). The average time from implant to IIB/IIIA use was 278 days (SD 365). 50% of patients had clinical resolution of their thrombus (80% tirofiban, 46% eptifibatide, p = 0.14). 29% of patients suffered a stroke, all of whom were exposed to eptifibatide (0% tirofiban vs 32% eptifibatide, p = 0.15). 43% of patients went on to eventual cardiac transplantation, 45% required pump exchange (0% tirofiban, 51% epitifibatide, p = 0.02), and 19% died in total from thrombotic complications, including pump exchange. There were no significant differences in the rate of stroke, pump exchange, or death with IIB/IIIA use when stratified by type of LVAD (HMII vs HeartWare). Conclusion IIB/IIIA inhibitors can be effective in treating suspected LVAD pump thrombus, with resolution of thrombus in half of cases in our experience. Whether outcomes differ based on the type of IIB/IIIA inhibitor used requires further investigation. The high proportion of patients who died or required pump exchange/eventual transplantation suggests that the use of IIB/IIIA inhibitors carries risk, and the effect may not be durable. Identification of patients and clinical scenarios that minimize risk and improve efficacy of IIB/IIA use is paramount.

Sleep and self-care correlates before and after implantation of a left-ventricular assist device (LVAD).

The impact of sleep on LVAD patients' self-care behaviors is unknown. This study examined the patterns and changes of patients sleep quality (SQ), daytime sleepiness (DS), instrumental activities of daily living (IADL), and self-care capability (SCC) before and after LVAD. In addition, the relationships among these variables were explored. This observational study consisted of 38 subjects from two VAD Centers in Michigan. The subjects completed self-reported demographics and psychometrically sound SQ, DS, IADL, and SCC questionnaires before LVAD implant and at 1, 3, and 6months after implant. Data were analyzed using descriptive statistics, linear mixed models, and partial least square models. Subjects (mean age, 56.3 ± 10.3years) were predominantly white (63%), male (68%), married (60%), and living with caregivers (92%). Over 70% had axial flow LVADs implanted as bridge-to-transplant (55%). Subjects' SQ was poor throughout the study period, along with high normal-to-excessive levels of DS. Problems with IADL before implant were significantly reduced at 1 through 6months after implant. SCC ranged from "good" to "excellent" before and after implant. Significant relationships between SQ and IADL (β = 0.43, p < 0.01) and DS and SCC (β=- 0.62, p < 0.01) were found. In conclusion, poor SQ and high degrees of DS were prevalent before and up to 6months after LVAD implant. The data inferred that the improvement in IADL was associated with an improvement in SQ. Research is needed to clarify the negative impact of DS on SCC and explain the contributions of caregivers on patients' SCC over time.

Usefulness of Speckle Tracking Strain Echocardiography for Assessment of Risk of Ventricular Arrhythmias After Placement of a Left Ventricular Assist Device

Patients with continuous-flow left ventricular assist devices (LVADs) are at elevated risk of developing ventricular arrhythmias (VA), which can result in right ventricular dysfunction and abnormal LVAD function. Predictors of postoperative VA after LVAD placement are unclear. We hypothesized that global left ventricular circumferential strain (LVCS), a marker of transmural impairment in myocardial function, would independently predict postoperative VA in patients who underwent LVAD implantation. We studied 98 consecutive patients (57 ± 11 years, 83% men) who underwent HeartMate II axial flow LVAD placement. Speckle tracking-derived global circumferential strain was assessed from mid-left ventricular short-axis images. The primary composite end point was defined as any ventricular tachycardia that required intervention (anti-arrhythmic medication, cardioversion, implantable cardioverter defibrillator placement, implantable cardioverter defibrillator shock) or any ventricular fibrillation. A total of 33 patients (34%) experienced the primary end point (median follow-up: 7 months). Reduced LVCS was statistically significantly related to the primary end point (hazard ratio 1.77, 95% confidence interval 1.09 to 2.87 per 1 standard deviation reduction in LVCS, p = 0.02). LVCS above a cut-off value of -9.7% was associated with significantly reduced arrhythmia-free survival (log-rank p = 0.001). In conclusion, global LVCS is an independent predictor of ventricular arrhythmias after LVAD placement.