Left ventricular assist device outcomes based on flow configuration and pre-operative left ventricular dimension: An Interagency Registry for Mechanically Assisted Circulatory Support Analysis

Left Ventricular Dimensions and Clinical Outcomes With a Fully Magnetically Levitated Left Ventricular Assist Device

BACKGROUND

Prior analyses have suggested that a smaller left ventricular end-diastolic diameter (LVEDD) is associated with reduced survival following HeartMate 3 left ventricular assist device implantation.

OBJECTIVES

In this trial-based comprehensive analysis, the authors sought to examine clinical characteristics and association with the outcome of this specific relationship.

METHODS

The authors analyzed the presence of LVEDD <55 mm among 1,921 analyzable HeartMate 3 patients within the MOMENTUM 3 (Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy With HeartMate 3) trial portfolio, on endpoints of overall survival and adverse events at 2 years. Adverse events included hemocompatibility-related (stroke, bleeding, and pump thrombosis) and non-hemocompatibility-related (right heart failure, infection) outcomes.

RESULTS

Those with a smaller LVEDD (<55 mm) (n = 108) were older (age 63 ± 11 years vs 60 ± 12 years; P = 0.005), were more often female (31% vs 20%; P = 0.096), and had more ischemic cardiomyopathy (60.2% vs 42.6%; P = 0.0004) compared with the LVEDD ≥55 mm group (n = 1,813). Death during implant hospitalization was higher (14.8 vs 5.7%; P = 0.0007) and survival at 2 years was lower (63.3% vs 81.8%; HR: 1.97 [95% CI: 1.39-2.79]; P = 0.0002) in the LVEDD <55 mm group. The LVEDD <55 mm group experienced more deaths due to hemocompatibility-related adverse events (2.8% vs 0.6%; HR: 4.61 [95% CI: 1.29-16.45]; P = 0.018) and right heart failure, both early (0-30 days; 7.4% vs 2.0%; HR: 3.70 [95% CI: 1.73-7.91]; P = 0.001) and late (>30 days; 12.0 vs 4.8%; HR: 2.58 [95% CI: 1.37-4.84]; P = 0.003). Low-flow alarms rehospitalizations were higher in the LVEDD <55 mm cohort (17.4 vs 8.3%; HR: 2.39 [95% CI: 1.59-3.59]; P < 0.001).

CONCLUSIONS

Although infrequent in occurrence, smaller LVEDD (<55 mm) is associated with increased risk for early and late mortality, a consequence of hemocompatibility-related and right heart failure-related deaths. Rehospitalizations due to low-flow alarms are also more frequent. (MOMENTUM 3 IDE Clinical Study Protocol [HM3™]; NCT02224755; MOMENTUM 3 Continued Access Protocol [MOMENTUM 3 CAP]; NCT02892955).

Features and outcomes of hypertrophic cardiomyopathy complicated by cardiogenic shock: an analysis of the FRENSHOCK multicenter prospective registry

OBJECTIVE

Cardiogenic shock (CS) in patients with left ventricular hypertrophy (LVH) due to hypertrophic cardiomyopathy (HCM) or hypertensive heart disease, is underreported in the literature. This study aimed to delineate the characteristics, management strategies, and outcomes of patients experiencing CS with preexisting LVH and HCM.

METHODS

FRENSHOCK is a prospective multicenter registry including 772 unselected CS patients from 49 centers. Baseline characteristics, management, and 1-year outcomes were analyzed according to the occurrence on preexisting LVH.

RESULTS

Among the 772 included patients with CS, CS occurred in 34 patients with preexisting LVH (4.4%, 1.4% with HCM). Clinical characteristics, medical history, usual medications, and hemodynamic parameters upon inclusion did not differ between the patients with or without LVH. Left ventricular ejection fraction in patients with CS and LVH was 27.3 ± 14.5% indicating a non-obstructive cause of CS. In-hospital management according to the LVH and non-LVH groups indicated no differences between the groups. The 1-month and 1-year mortality did not differ between patients with CS with and without LVH (26.5% vs. 26%, adjusted HR [hazard ratio] [95% CI]: 0.87 [0.44-1.72]) and 55.9% vs. 44.7%, respectively (adjusted HR [95% CI]:0.88 [0.54-1.42]). Subgroup analyses comparing HCM (n = 11) and hypertensive LVH (n = 23) revealed similar clinical characteristics, in-hospital management, and one-year rehospitalization rates in these patients.

CONCLUSION

In a large and unselected CS population, the prevalence of patients with LVH was low (4.4%) with less than half having HCM (1.4%). The presentation, management, and outcomes of CS were similar to the broader CS population in our series. However, HCM-CS represents a distinct clinical entity necessitating tailored management approaches.

Dynamic Risk Estimation of Adverse Events in Ambulatory LVAD Patients: A MOMENTUM 3 Analysis

BACKGROUND

Hemocompatibility-related adverse events affect patients after left ventricular assist device (LVAD) implantation but are hard to predict.

OBJECTIVES

Dynamic risk modeling with a multistate model can predict risk of gastrointestinal bleeding (GIB), stroke, or death in ambulatory patients.

METHODS

This was a secondary analysis of the MOMENTUM 3 (Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy with HeartMate 3) trial. HeartMate 3 LVAD recipients who survived to hospital discharge and were followed for up to 2 years. A total of 145 variables were included in the multistate model with multivariate logistic regression. Model performance was assessed with the area under the curve in a holdout validation cohort. A risk stratification tool was created by dividing patients into categories of predicted risk using the final model variables and associated OR.

RESULTS

Among 2,056 LVAD patients, the median age was 59.4 years (20.4% women, 28.6% Black). At 2 years, the incidence of GIB, stroke, and death was 25.6%, 6.0%, and 12.3%, respectively. The multistate model included 39 total variables to predict risk of GIB (16 variables), stroke (10 variables), and death (19 variables). When ambulatory patients were classified according to their risk category, the 30-day observed event rate in the highest risk group for GIB, stroke, or death was 26.9%, 1.8%, and 4.8%, respectively. The multistate model predicted GIB, stroke, and death at any 30-day period with an area under the curve of 0.70, 0.69, and 0.86, respectively.

CONCLUSIONS

The multistate model informs 30-day risk in ambulatory LVAD recipients and allows recalculation of risk as new patient-specific data become available. The model allows for accurate risk stratification that predicts impending adverse events and may guide clinical decision making. (MOMENTUM 3 IDE Clinical Study Protocol; NCT02224755).

Hypertrophic Cardiomyopathy: From Medical Treatment to Advanced Heart Failure Therapies

PURPOSE OF REVIEW

There has been much debate surrounding novel medical therapies and heart transplantation listing challenges in patients with hypertrophic cardiomyopathy (HCM).

RECENT FINDINGS

Recent clinical trials led to FDA approval of mavacamten (a cardiac myosin inhibitor), offering symptom relief and potentially delaying/avoiding invasive septal reduction therapies for some patients with HCM and left ventricular outflow obstruction (LVOTO). For those with refractory symptoms and end-stage heart failure, heart transplantation remains the gold standard. However, the concern for the organ allocation system failing to prioritize those individuals persists. HCM is a heterogeneous genetic condition with variable penetration and clinical presentation. Even though a large portion of patients remain asymptomatic, an important minority develops debilitating symptoms refractory to medical therapy. Post-HT short- and long-term outcomes are favorable. However, HT waitlist mortality remains high. For highly selected patients with HCM, a left ventricular assist device is a viable option.

Impella 5.5 in left ventricular noncompaction syndrome as bridge to heart transplant

Background

Left ventricular non-compaction syndrome (LVNC) is an uncommon congenital disease characterized by prominent trabeculations and deep inter-trabecular recesses of the left ventricle wall. We present the first reported case of Impella 5.5 use in LVNC as a bridge to transplant in a highly sensitized patient.

Methods

A 50-year-old female with a family history of sudden cardiac death, LVNC cardiomyopathy associated with TPM1 gene mutation, and recurrent hospitalizations due to heart failure was listed for heart transplantation. She had severely reduced systolic function (EF 20%) and high panel reactive antibodies (PRA). She was admitted for desensitization therapy. Hospitalized, she escalated to Dobutamine and Milrinone due to progressive shock. Impella 5.5 was inserted, and inotropes were reduced as her condition steadied. She tolerated desensitization and eventually underwent heart transplantation after 120 days of continuous Impella 5.5 support without developing hemolysis or pump thrombosis.

Results

Post-transplant she was found to have concern for left sided stroke symtpoms but completely recovered and remians stable on follow up at 6 months. Due to the lack of prospective trials with large cohorts, managing patients with LVNC and cardiogenic shock is challenging. Novel approaches to complex patients with both Impella 5.5 support and desensitization therapies should be considered in the appropriate setting.

Conclusion

Our case highlights the use of mechanical circulatory support in the management of cardiogenic shock within a small left ventricluar cavity in a sensitized patient. This approach should be considered in high-risk patients in whom durable left ventricular assist therapy is not feasible.

A multicenter evaluation of the HeartMate 3 risk score

BACKGROUND

The Heartmate 3 (HM3) risk score (HM3RS) was derived and validated internally from within the Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy with HeartMate 3 (MOMENTUM 3) trial population and provides 1- and 2-year mortality risk prediction for patients in those before HM3 left ventricular assist device (LVAD) implantation. We aimed to evaluate the HM3RS in nontrial unselected patients, including those not meeting inclusion criteria for MOMENTUM 3 trial enrollment.

METHODS

Patients who underwent HM3 LVAD implant at 1 of 7 US centers between 2017 and 2021, with at least 1-year follow-up, were included in this analysis. Patients were retrospectively assessed for their eligibility for the MOMENTUM 3 trial based on study inclusion and exclusion criteria. HM3RS risk discrimination was evaluated using time-dependent receiver operating characteristic curve analysis for 1-year mortality for all patients and further stratified by MOMENTUM 3 trial eligibility. Kaplan-Meier curves were constructed using the HM3RS-based risk categories.

RESULTS

Of 521 patients included in the analysis, 266 (51.1%) would have met enrollment criteria for MOMENTUM 3. The 1- and 2-year survival for the total cohort was 85% and 81%, respectively. There was no statistically significant difference in survival between those who met and did not meet enrollment criteria at 1 (87% vs 83%; p = 0.21) and 2 years postimplant (80% vs 78%; p = 0.39). For the total cohort, HM3RS predicted 1-year survival with an area under the curve (AUC) of 0.63 (95% confidence interval [CI]: 0.57-0.69, p < 0.001). HM3RS performed better in the subset of patients meeting enrollment criteria: AUC 0.69 (95% CI:0.61-0.77, p < 0.001) compared to the subset that did not: AUC 0.58 (95% CI: 0.49-0.66, p = 0.078).

CONCLUSIONS

In this real-world evidence, multicenter cohort, 1- and 2-year survival after commercial HM3 LVAD implant was excellent, regardless of trial eligibility. The HM3RS provided adequate risk discrimination in "trial-like" patients, but predictive value was reduced in patients who did not meet trial criteria.

Advanced Heart Failure Therapies for Hypertrophic Cardiomyopathy: State-of-the-Art Review and an Updated Analysis From UNOS

Hypertrophic cardiomyopathy (HCM) is most commonly associated with obstructive symptoms and sudden cardiac death; however, predominantly nonobstructive advanced heart failure in HCM, marked by medically refractory disease with severe functional impairment, occurs in 5% to 7% of patients with HCM. The diagnosis relies on the integration of imaging (echocardiography/cardiac magnetic resonance), hemodynamic data, and cardiopulmonary exercise testing to identify the patients who will benefit from advanced heart failure therapies. Most advanced heart failure therapies focus on systolic dysfunction and are not always applicable to this patient population. Left ventricular assist devices may be an option in a highly selected population with left ventricular dilation. Heart transplantation is often the best option for patients with advanced heart failure in HCM with excellent post-transplantation survival.

Prediction, prevention, and management of right ventricular failure after left ventricular assist device implantation: A comprehensive review

Left ventricular assist devices (LVADs) are increasingly common across the heart failure population. Right ventricular failure (RVF) is a feared complication that can occur in the early post-operative phase or during the outpatient follow-up. Multiple tools are available to the clinician to carefully estimate the individual risk of developing RVF after LVAD implantation. This review will provide a comprehensive overview of available tools for RVF prognostication, including patient-specific and right ventricle (RV)-specific echocardiographic and hemodynamic parameters, to provide guidance in patient selection during LVAD candidacy. We also offer a multidisciplinary approach to the management of early RVF, including indications and management of right ventricular assist devices in this setting to provide tools that help managing the failing RV.

A Computational Hemodynamics Approach to Left Ventricular Assist Device (LVAD) Optimization Validated in a Large Patient Cohort

With increasing use of left ventricular assist devices (LVAD) it is critical to devise strategies to optimize LVAD speed while controlling mean arterial pressure (MAP) and flow according to patient physiology. The complex interdependency between LVAD speed, MAP, and flow frequently makes optimization difficult under clinical conditions. We propose a method to guide this procedure in silico, narrowing the conditions to test clinically. A computational model of the circulatory network that simulates HF and LVAD support, incorporating LVAD pressure-flow curves was applied retrospectively to anonymized patient hemodynamics data from the University of Washington Medical Center. MAP management on 61 patient-specific computational models with a target of 70 mm Hg, resulting flow for a given LVAD speed was analyzed, and compared to a target output of 5 L/min. Before performing virtual MAP management, 51% had a MAP>70 mm Hg and CO>5 L/min, and 33% had a MAP>70 mm Hg and CO<5 L/min. After changing systemic resistance to meet the MAP target (without adjusting LVAD speed), 84% of cases resulted in CO higher than 5 L/min, with a median CO of 6.79 L/min, using the computational predictive model. Blood pressure management alone is insufficient in meeting both MAP and CO targets, due to the risk of hypervolemia, and requires appropriate LVAD speed optimization to achieve both targets, while preserving right heart health. Such computational tools can narrow down conditions to be tested for each patient, providing significant insight into the pump-patient interplay. LVAD hemodynamic optimization has the potential to reduce complications and improve outcomes.

Mechanical and interventional support for heart failure with preserved ejection fraction: A review

INTRODUCTION

Restrictive cardiomyopathy (RCM) and hypertrophic cardiomyopathy (HCM) are two disease processes that are known to progress to heart failure with preserved ejection fraction (HFpEF). Pharmacologic therapies for HFpEF have not improved patient outcomes or reduced mortality in this patient cohort; thus, there continues to be substantial interest in other treatment strategies, including surgical interventions and devices. In this article, we explore and report the current utility of percutaneous therapies and surgically implanted mechanical support in the treatment of patients with HFpEF.

RESULTS

Treatment strategies include percutaneous interventions with interatrial shunts, left atrial assist devices (LAADs), and ventricular assist devices (VADs) in various configurations. Although VADs have been employed to treat patients with heart failure with reduced ejection fraction, their efficacy is limited in those with RCM and HCM. A left atrial-to-aortic VAD has been proposed to directly unload the left atrium, but data is limited. Alternatively, a LAAD could be placed in the mitral position and simultaneously unload the left atrium, while filling the left ventricle.

CONCLUSION

A left atrial assist device in the mitral position is a promising solution to address the hemodynamic abnormalities in RCM and HCM; these pumps, however, are still under development.

Outcomes in Smaller Body Size Adults after HeartMate 3 Left Ventricular Assist Device Implantation

BACKGROUND

Outcomes in patients with smaller body size following HeartMate 3 Left Ventricular Assist Device (HM3) implantation are not well characterized. We sought to evaluate outcomes in smaller vs. larger BSA patients in the MOMENTUM 3 pivotal trial and its Continued Access Protocol cohort.

METHODS

The analysis cohort included 1015 HM3 patients divided into 2 groups: BSA≤1.70 m² (small patients, n=82) and BSA>1.70 m² (large patients, n=933). The composite primary endpoint was survival at 2-years free of disabling stroke or reoperation to replace or remove a malfunctioning device. Adverse events were compared between groups.

RESULTS

Smaller patients were more frequently women (56.1% vs. 17.7%, P<.001), had lower prevalence of diabetes (28.1% vs. 43.9%, P=.005) and hypertension (51.2% vs. 71.9%, P<.001), larger median indexed LVEDD (normalized by BSA, 40 vs. 33 mm/m², P<.001), and lower median serum creatinine (1.1 vs. 1.3 mg/dl, P<.001). The proportion of patients achieving the composite endpoint at 2-years was 77% in both groups (adjusted HR = 1.14 [95% confidence interval: 0.68-1.91], P=.62). Two-year adverse event rates were also similar between groups except for sepsis (6.1% vs. 14.9%, P=.029) and cardiac arrhythmias (24.4% vs. 35.3%, P=.005), which were higher in the larger patients.

CONCLUSIONS

Outcomes following HM3 implantation were comparable between small and large patients. Smaller body size should not be used to deny HM3 implantation in patients who are otherwise suitable durable MCS candidates.

Left Ventricular End-Diastolic Dimension and Clinical Outcomes After Centrifugal Flow Left Ventricular Assist Device Implantation

The impact of preoperative end-diastolic left ventricular dimension (preLVEDD) on long-term outcomes with centrifugal continuous-flow left ventricular assist device (CF-LVAD) is not well established. Accordingly, we performed an analysis of the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) registry to study this relationship. All patients with centrifugal CF-LVAD in the INTERMACS registry from June 2006 to December 2017 were screened. The final study group consisted of 3,304 patients. After a median follow-up of 9.0 months (interquartile range [IQR], 4.2-18.8 months), 2,596 (79%) patients were alive. After adjusting for significant covariates, increased preLVEDD was associated with lower mortality (hazard ratio [HR], 0.91; 95% confidence interval [CI], 0.84-0.98; p = 0.01), stroke (HR, 0.85; 95% CI, 0.77-0.93; p < 0.001), and gastrointestinal bleeding (HR, 0.88; 95% CI, 0.80-0.97; p = 0.01), although there were more arrhythmias (HR, 1.14; 95% CI, 1.05-1.24; p = 0.003). Our study suggests that preLVEDD is an independent predictor of mortality and adverse events in patients treated with centrifugal CF-LVAD. preLVEDD should be considered an important preimplant variable for risk stratification when considering a CF-LVAD.

Does Size Matter for Female Continuous-flow LVAD Recipients? A Translational Approach to a Decade Long Question

Females have increased risk of right-ventricular failure (RVF) and 3 month mortality after left-ventricular assist device (LVAD) implantation. In this translational study, we tested the hypothesis that sex differences in outcomes are driven by pump-induced LV size-volume mismatch, due to a negative impact on interventricular septal (IVS) interdependence. Adult continuous-flow LVAD recipients from the International Society For Heart And Lung Transplantation Mechanically Assisted Circulatory Support registry (n = 15,498) were studied to determine association of female sex with outcomes of 3 month mortality and RVF. Female sex was associated with smaller preimplant left-ventricular end-diastolic diameter (6.5 vs. 6.9 cm, p < 0.001), increased 3 month mortality (odds ratio [OR]: 1.42, p < 0.001) and RVF (OR: 1.18, p = 0.005). Smaller left-ventricular end-diastolic diameter was associated with worse outcomes after LVAD implantation (OR for mortality: 1.20, p < 0.001; RVF: 1.09, p < 0.001), and attenuated the association of female sex with these outcomes. In test bench heart phantoms (n = 4), the IVSs of smaller hearts demonstrated abnormal leftward shift earlier than larger hearts (volume change at IVS shift: 40 [95% confidence interval: 30-52] vs. 50 [95% confidence interval: 48-69] ml). Smaller LV size partially mediates worse post-LVAD outcomes for female patients, due to lower volume thresholds for adverse IVS shifting.

The impact of left ventricular size on outcomes after centrifugal-flow left ventricular assist device implantation

OBJECTIVES

The influence of preoperative left ventricular size in outcomes following centrifugal-flow left ventricular assist device (LVAD) implantation has not been well characterized.

METHODS

A cohort of 313 patients who received a centrifugal-flow LVAD at a single institution was analysed. Using a maximally selected log-rank statistic, we investigated whether a left ventricular end-diastolic dimension (LVEDD) cut-off point was associated with worse outcomes. The cohort was then divided in 2 groups based on the LVEDD cut-off point.

RESULTS

An LVEDD cut-off point of 59 mm was found to predict worse survival. Smaller LVEDD patients (≤59 mm, N = 52) were older and more likely to have a history of coronary artery disease compared those with a larger LVEDD (>59 mm, N = 261). Smaller LVEDD patients had lower survival compared to larger LVEDD patients (71% vs 85% at 1 year and 58% vs 80% at 2 years, P = 0.003). The need for temporary right ventricular mechanical support was significantly higher in the smaller LVEDD cohort (11.5% vs 1.9%, P = 0.002). Pump flows at time of discharge were lower in the smaller LVEDD group (3.8 vs 4.2 l/min, P = 0.005), who also had a higher incidence of late right ventricular failure (23% vs 12%, P = 0.02), higher rates of gastrointestinal bleeding (0.416 vs 0.256 events per patient-year, P = 0.025) and higher readmissions secondary to low flow alarms (0.429 vs 0.240 events per patient-year, P = 0.007). Multivariable analysis demonstrated that smaller LVEDD, older age, high BUN and high bilirubin levels were independent predictors of worse survival.

CONCLUSIONS

In patients receiving a centrifugal-flow LVAD, smaller preoperative LVEDD (≤59 mm) was associated with lower survival and higher incidence of adverse outcomes.

Pre-implant left ventricular dimension is not associated with worse outcomes after left ventricular assist device implantation

Background

Left ventricular dimension has the potential to impact clinical outcomes following implantation of left ventricular assist devices (LVAD). We investigated the effect of pre-implant left ventricular end-diastolic diameter (LVEDD) on outcomes following LVAD implantation.

Methods

Patients implanted with a continuous-flow LVAD between 2004 and 2018 at a single institution were included. The primary outcome was death while on LVAD support. Secondary outcomes included adverse event rates such as renal failure requiring dialysis, device thrombosis, and right ventricular failure. The LVEDD measurements were dichotomized using restricted cubic splines and threshold regression. Survival was determined using Kaplan-Meier estimates. Multivariable logistic regression was used to determine risk-adjusted mortality based on LVEDD.

Results

A total of 344 patients underwent implantation of a continuous flow LVAD during the study period. The optimal cut point for LVEDD was 65 mm, with 126 (36.6%) subjects in the <65 mm group and 165 (48.0%) in the >65 mm group. The LVEDD <65 mm group was older, had more females, higher incidence of diabetes, more pre-implant mechanical ventilation, and more admissions for acute myocardial infarctions (all, P<0.05). Importantly, post-implant adverse events were similar between the groups (all, P>0.05). Risk-adjusted survival at 1-year (OR 1.3, 95% CI: 0.6–2.5, P=0.53) was also comparable between the groups. Furthermore, incremental increases in LVEDD when modeled as a continuous variable did not impact overall mortality (OR 0.98, 95% CI: 0.9–1.0, P=0.09).

Conclusions

Preoperative LVEDD was not associated with rates of major morbidities or mortality following LVAD implantation.

Left Ventricular Assist Device Implantation in Patients with Preoperative Severe Mitral Regurgitation

We examined cardiac features associated with residual mitral regurgitation (MR) following continuous-flow left ventricular assist device (cfLVAD) implant. From 2003 to 2017, 134 patients with severe MR underwent cfVLAD implant without mitral valve (MV) intervention. Echocardiographic (echo) assessment occurred pre-cfLVAD, early post-cfLVAD, and at last available echo. Ventricular and atrial volumes were calculated from established formulas and normalized to be predicted. Cluster analysis based on preoperative normalized left ventricular and atrial volumes, and MV height identified grades 1, 2, and 3 with progressively larger cardiac chamber sizes. Median early echo follow-up was 0.92 (0.55, 1.45) months and the last follow-up was 15.12 (5.28, 38.28) months. Mitral regurgitation improved early after cfLVAD by 2.10 ± 1.16 grades (p < 0.01). Mitral regurgitation severity at the last echocardiogram positively correlated with the preoperative left ventricular volume (p = 0.014, R = 0.212), left atrial volume (p = 0.007, R = 0.233), MV anteroposterior height (p = 0.032, R = 0.185), and MV mediolateral diameter (p = 0.043, R = 0.175). Morphologically, smaller grade 1 hearts were correlated with MR resolution at the late follow-up (p = 0.023). Late right ventricular failure (RVF) at the last clinical follow-up was less in grade 1 (4/48 [8.3%]) compared with grades 2 and 3 (26/86 [30.2%]), p = 0.004). Grade 1 cardiac dimensions correlates with improvement in severe MR and had less late RVF.

Effect of Timings of the Lavare Cycle on the Ventricular Washout in an In Vitro Flow Visualization Setup

Left ventricular assist devices inherently alter the intraventricular flow field and create areas of blood stasis with potential thrombus formation. The Lavare cycle of the Medtronic HeartWare HVAD was designed to improve ventricular washout. This study aims to evaluate its effects on ventricular washout in a pulsatile in vitro setting with a focus on the timing of pump speed changes. Ventricular flow fields were obtained via particle image velocimetry in two modes: With constant left ventricular assist devices speed and with the Lavare cycle applied. The start of the Lavare cycle was shifted over an entire cardiac cycle, and ventricular washout was evaluated based on velocity fields, kinetic energy, and normalized pulsatility of flow fields. The ventricular flow fields showed dependence on the timing of the Lavare cycle and interaction between speed changes and the cardiac phase. Higher apical velocity was observed for speed decreases at the late E wave and for increases at mid systole by 29% (P = 0.002) and 61% (P < 0.001), respectively. Mean apical kinetic energy for these phases also increased by 21% (P = 0.0013) and 46% (P < 0.001). The Lavare cycle generally promotes higher apical washout and can specifically generate further improved washout if speed steps are applied at the correct timing on the cardiac cycle.

Gender Differences in Mortality After Left Ventricular Assist Device Implant: A Causal Mediation Analysis Approach

We used the International Society for Heart and Lung Transplantation (ISHLT) Registry for Mechanically Assisted Circulatory Support (IMACS) database to examine 1) gender differences in post-left ventricular assist device (LVAD) mortality in the contemporary era and 2) preimplant clinical factors that might mediate any observed differences. Adults who received continuous-flow (CF)-LVAD from January 2013 to September 2017 (n = 9,565, age: 56.2 ± 13.2 years, 21.6% female, 31.1% centrifugal pumps) were analyzed. An inverse probability weighted Cox proportional hazards model was used to estimate association of female gender with all-cause mortality, adjusting for known covariates. Causal mediation analysis was performed to test plausible preimplant mediators mechanistically underlying any association between female gender and mortality. Females had higher mortality after LVAD (adjusted hazard ratio [HR]: 1.36; p < 0.0001), with significant gender × time interaction (p = 0.02). An early period of increased risk was identified, with females experiencing a higher risk of mortality during the first 4 months after implant (adjusted HR: 1.74; p < 0.0001), but not after (adjusted HR: 1.18; p = 0.16). More severe tricuspid regurgitation and smaller left ventricular end-diastolic diameter at baseline mediated ≈21.9% of the increased early hazard of death in females; however, most of the underlying mechanisms remain unexplained. Therefore, females have increased mortality only in the first 4 months after LVAD implantation, partially driven by worsening right ventricular dysfunction and LV-LVAD size mismatch.

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.

Impact of anatomical position of the inflow cannula on stroke in patients with left ventricular assist devices

OBJECTIVES

Stroke is a substantial complication of left ventricular assist device (LVAD) implantation. The relationship between stroke and the anatomical position of the inflow cannula of patients who underwent LVAD implantation was investigated.

METHODS

We enrolled 15 patients with advanced-stage heart failure who underwent implantation of continuous-flow-LVAD. Data of patients who suffered a stroke within 6 months after LVAD implantation were retrospectively compared to those who remained free of stroke. The distance between the inflow duct and left ventricular (LV) septum (duct-sep distance) and its ratio to LV diastolic diameter (LVDd) were measured from echocardiography at 1 month after LVAD implantation. Receiver operating characteristic curves for the endpoint of stroke using the duct-sep distance to LVDd ratio was created and the cut-off value was calculated. The incidence of stroke during the 6 months after LVAD implantation according to this ratio was estimated using the Kaplan-Meier method.

RESULTS

At 1 month after LVAD implantation, there were no significant differences in baseline characteristics and echocardiography parameters between the stroke and stroke-free groups. Receiver operating characteristic curve analysis for the endpoint of stroke using the duct-sep distance to LVDd ratio revealed 0.217 as a cut-off value (sensitivity: 80%, specificity: 80%, area under the curve: 0.72). Stroke was more frequent in patients with a duct-sep distance to LVDd ratio ⩾0.217 at 1 month than in those with a lower ratio.

CONCLUSION

The duct-sep distance to LVDd ratio was associated with the occurrence of stroke, suggesting that inflow cannula position influences the incidence of stroke.

Small Left Ventricular Size Is an Independent Risk Factor for Ventricular Assist Device Thrombosis

The prevalence of ventricular assist device (VAD) therapy has continued to increase due to a stagnant donor supply and growing advanced heart failure (HF) population. We hypothesize that left ventricular (LV) size strongly influences biocompatibility and risk of thrombosis. Unsteady computational fluid dynamics (CFD) was used in conjunction with patient-derived computational modeling and virtual surgery with a standard, apically implanted inflow cannula. A dual-focus approach of evaluating thrombogenicity was employed: platelet-based metrics to characterize the platelet environment and flow-based metrics to investigate hemodynamics. Left ventricular end-diastolic dimensions (LVEDds) ranging from 4.5 to 6.5 cm were studied and ranked according to relative thrombogenic potential. Over 150,000 platelets were individually tracked in each LV model over 15 cardiac cycles. As LV size decreased, platelets experienced markedly increased shear stress histories (SHs), whereas platelet residence time (RT) in the LV increased with size. The complex interplay between increased SH and longer RT has profound implications on thrombogenicity, with a significantly higher proportion of platelets in small LVs having long RT times and being subjected to high SH, contributing to thrombus formation. Our data suggest that small LV size, rather than decreased VAD speed, is the primary pathologic mechanism responsible for the increased incidence of thrombosis observed in VAD patients with small LVs.

Anesthetic management of a patient with a continuous-flow left ventricular assist device for video-assisted thoracoscopic surgery: a case report

Background

As patients with left ventricular assist device (LVAD) have long expected survival, the incidence of noncardiac surgery in this patient population is increasing. Here, we present the anesthetic management of a patient with a continuous-flow LVAD who underwent video-assisted thoracic surgery (VATS).

Case presentation

A 37-year-old man with LVAD was scheduled to undergo VATS because of repeated spontaneous pneumothorax. Generally, patients with these devices have marginal right heart function; therefore, it is important to avoid factors that worsen pulmonary vascular resistance (PVR). However, VATS requires one-lung ventilation (OLV) and it tends to cause increase in PVR, leading to right heart failure.

In the present case, when the patient was set in a lateral decubitus position and progressive hypoxia was observed during OLV, transesophageal echocardiography demonstrated a dilated right ventricle and a temporally flattened interventricular septum, and the central venous pressure increased to approximately 20 mmHg. Because we anticipated deterioration of right heart function, dobutamine and milrinone were administered and/or respirator settings were changed to decrease PVR for maintaining LVAD performance. Finally, resection of a bulla was completed, and the patient was discharged in stable condition on postoperative day 37.

Conclusions

The anesthetic management of a patient with LVAD during VATS is challenging because the possible hemodynamic changes induced by hypoxia associated with OLV affect LVAD performance and right heart function. In our experience, VATS that requires OLV will be well tolerated in a patient with LVAD with preserved right heart function, and a multidisciplinary approach to maintain right heart function will be needed.

Ultrasonic sensor concept to fit a ventricular assist device cannula evaluated using geometrically accurate heart phantoms

Future left ventricular assist devices (LVADs) are expected to respond to the physiologic need of patients; however, they still lack reliable pressure or volume sensors for feedback control. In the clinic, echocardiography systems are routinely used to measure left ventricular (LV) volume. Until now, echocardiography in this form was never integrated in LVADs due to its computational complexity. The aim of this study was to demonstrate the applicability of a simplified ultrasonic sensor to fit an LVAD cannula and to show the achievable accuracy in vitro. Our approach requires only two ultrasonic transducers because we estimated the LV volume with the LV end-diastolic diameter commonly used in clinical assessments. In order to optimize the accuracy, we assessed the optimal design parameters considering over 50 orientations of the two ultrasonic transducers. A test bench was equipped with five talcum-infused silicone heart phantoms, in which the intra-ventricular surface replicated papillary muscles and trabeculae carnae. The end-diastolic LV filling volumes of the five heart phantoms ranged from 180 to 480 mL. This reference volume was altered by ±40 mL with a syringe pump. Based on the calibrated measurements acquired by the two ultrasonic transducers, the LV volume was estimated well. However, the accuracies obtained are strongly dependent on the choice of the design parameters. Orientations toward the septum perform better, as they interfere less with the papillary muscles. The optimized design is valid for all hearts. Considering this, the Bland-Altman analysis reports the LV volume accuracy as a bias of ±10% and limits of agreement of 0%-40% in all but the smallest heart. The simplicity of traditional echocardiography systems was reduced by two orders of magnitude in technical complexity, while achieving a comparable accuracy to 2D echocardiography requiring a calibration of absolute volume only. Hence, our approach exploits the established benefits of echocardiography and makes them applicable as an LV volume sensor for LVADs.

A Comprehensive Imaging Approach to Guide the Management of Patients with Continuous-Flow Left Ventricular Assist Devices

Recent advances in mechanical circulatory support have allowed patients with end-stage heart failure to be successfully bridged to heart transplantation or live for many years on continuous-flow left ventricular assist devices (CF-LVADs) as destination therapy. As survival and quality of life continue to improve and the number of patients supported by CF-LVADs continues to grow, utilization of different imaging modalities in the care for these patients has become an integral part of many heart failure centers. We review currently available imaging modalities, with a focus on echocardiography, that aid to diagnose and manage common adverse events associated with CF-LVADs.

Antithrombotic Strategies and Device Thrombosis

Despite improvements in left ventricular assist device (LVAD) technology, bleeding and thrombotic complications are major concerns that adversely influence morbidity and mortality. Current antithrombotic therapy recommendations for LVAD thrombosis prophylaxis are largely derived from clinical device trials that implement a one-size-fits-all strategy. Objective serial laboratory-based assessment of thrombogenicity is needed to balance the risk of bleeding and thrombotic complications. Finally, the newest-generation device, the HeartMate 3, has been associated with lower levels of shear and reduced hemolysis that may mitigate thrombotic event occurrences.