Gastrointestinal bleeding following Heartmate 3 left ventricular assist device implantation: The Michigan Bleeding Risk Model

BACKGROUND

Gastrointestinal bleeding (GIB) results in frequent hospitalizations and impairs quality of life in durable left ventricular assist device (LVAD) recipients. Anticipation of these events before implantation could have important implications for patient selection and management.

METHODS

The study population included all adult HeartMate 3 (HM3) primary LVAD recipients enrolled in the STS Intermacs registry from January 2017 to December 2020. Using multivariable modeling methodologies, we investigated the relationships between preimplantation characteristics and postimplant bleeding, bleeding and death, and additional bleeding episodes on subsequent bleeding episodes and created a risk score to predict the likelihood of post-LVAD GIB based solely on preimplantation factors.

RESULTS

Of 6,425 patients who received an HM3 LVAD, 1,010 (15.7%) patients experienced GIB. Thirteen preimplantation factors were independent predictors of post-LVAD GIB. A risk score was created from these factors and calculated for each patient. By 3 years postimplant, GIB occurred in 11%, 26%, and 43% of low-, medium- and high-risk patients, respectively. Experiencing 1 post-LVAD GIB event was associated with an increased risk for further GIB events, with 33.9% of patients experiencing at least 1 recurrence. While post-LVAD GIB was associated with mortality, there was no relationship between number of GIB events and death.

CONCLUSIONS

The Michigan Bleeding Risk Model is a simple tool, which facilitates the prediction of post-LVAD GIB in HM3 recipients using 13 preimplant variables. The implementation of this tool may help in the risk stratification process and may have therapeutic and clinical implications in HM3 LVAD recipients.

Mechanical Analysis of a Novel Sternal Closure System in Static Tensile Loading

The most common means of sternal closure after sternotomy is stainless steel wire cerclage. These wires, while inexpensive and simple in design, are known to be associated with low strength and sternal dehiscence. In this biomechanical analysis, we compare single sternal wires, double sternal wires, and a novel sternal closure device we have designed to mitigate sternal dehiscence. The device uses polymer grommets at the sternal interfaces to distribute load over a large surface area of bone. Samples of each closure device were installed in a bone model and distracted at a rate of 10 mm/min while tensile forces were continuously measured and compared. Single wires generated the lowest stiffness and strength values, followed by the double wires. The novel device demonstrated significantly higher stiffness and strength at all displacements compared with the single and double wires. Clinical use of this device may result in meaningful reduction in complications associated with the use of standard sternal wires such as sternal separation and fracture.

Determinants of survival following heart transplantation in adults with congenital heart disease

BACKGROUND

Adult patients surviving with congenital heart disease (ACHD) is growing. We examine the factors associated with heart transplant outcomes in this challenging population with complex anatomy requiring redo-surgeries.

METHODS

We reviewed the United Network for Organ Sharing-Standard Transplant Analysis and Research database and analyzed 35,952 heart transplants from January 1st, 2000, to September 30th, 2018. We compared transplant characteristics for ischemic cardiomyopathy (ICM) (n = 14,236), nonischemic cardiomyopathy (NICM) (n = 20,676), and ACHD (n = 1040). Mean follow-up was 6.20 ± 4.84 years. Kaplan-Meier survival curves and Cox-proportional hazards analysis were used to analyze survival data.

RESULTS

Multivariable analysis confirmed that ACHD was associated greater in-hospital death compared to ICM (HR = 0.54, P < 0.001) and NICM (HR = 0.46, P < 0.001). Notable factors associated with increased mortality were history of cerebrovascular disease (HR = 1.11, P = 0.026), prior history of malignancy (HR = 1.12, P = 0.006), pre-transplant biventricular support (HR = 1.12, P = 0.069), postoperative stroke (HR = 1.47, P < 0.001) and postoperative dialysis (HR = 1.71, P < 0.001). ACHD transplants had a longer donor heart ischemic time (P < 0.001) and trend towards more deaths from primary graft dysfunction (P = 0.07). In-hospital deaths were more likely with ACHD and use of mechanical support such as use of right ventricular assist device (HR = 2.20, P = 0.049), biventricular support (HR = 1.62, P < 0.001) and extracorporeal membrane oxygenation (HR = 2.36, P < 0.001). Conditional survival after censoring hospital deaths was significantly higher in ACHD (P < 0.001).

CONCLUSION

Heart transplant in ACHD is associated with a higher post-operative mortality given anatomical complexity but a better long-term conditional survival. Normothermic donor heart perfusion may improve outcomes in the ACHD population by reducing the impact of longer ischemic times.

Modeling and estimating a threshold effect: An application to improving cardiac surgery practices

Estimating thresholds when a threshold effect exists has important applications in biomedical research. However, models/methods commonly used in the biomedical literature may lead to a biased estimate. For patients undergoing coronary artery bypass grafting (CABG), it is thought that exposure to low oxygen delivery (DO2) contributes to an increased risk of avoidable acute kidney injury. This research is motivated by estimating the threshold of nadir DO2 for CABG patients to help develop an evidence-based guideline for improving cardiac surgery practices. We review several models (sudden-jump model, broken-stick model, and the constrained broken-stick model) that can be adopted to estimate the threshold and discuss modeling assumptions, scientific plausibility, and implications in estimating the threshold. Under each model, various estimation methods are studied and compared. In particular, under a constrained broken-stick model, a modified two-step Newton-Raphson algorithm is introduced. Through comprehensive simulation studies and an application to data on CABG patients from the University of Michigan, we show that the constrained broken-stick model is flexible, more robust, and able to incorporate scientific knowledge to improve efficiency. The two-step Newton-Raphson algorithm has good computational performances relative to existing methods.

Open Surgical Treatment of Acute and Chronic Pulmonary Embolism

Acute pulmonary embolism (PE) is a common cause of death and morbidity in the United States and the prevalence of chronic thromboembolic pulmonary hypertension (CTEPH), a possible sequela of PE, has increased during the past decade. The mainstay treatment of CTEPH is open pulmonary endarterectomy, a procedure performed under hypothermic circulatory arrest, which entails endarterectomy of the branch, segmental and subsegmental pulmonary arteries. Acute PE may be similarly be treated with an open embolectomy in certain select circumstances.

ECMO During COVID-19: A Society of Thoracic Surgeons/Extracorporeal Life Support Organization Survey

BACKGROUND

The Society of Thoracic Surgeons Workforce on Critical Care and the Extracorporeal Life Support Organization sought to identify how the coronavirus disease 2019 (COVID-19) pandemic has changed the practice of venoarterial (VA) and venovenous (VV) extracorporeal membrane oxygenation (ECMO) programs across North America.

METHODS

A 26-question survey covering 6 categories (ECMO initiation, cannulation, management, anticoagulation, triage/protocols, and credentialing) was emailed to 276 North American Extracorporeal Life Support Organization centers. ECMO practices before and during the COVID-19 pandemic were compared.

RESULTS

Responses were received from 93 (34%) programs. The percentage of high-volume (>20 cases per year) VV ECMO programs increased during the pandemic from 29% to 41% (P < .001), as did institutions requiring multiple clinicians for determining initiation of ECMO (VV ECMO, 25% to 43% [P = .001]; VA ECMO, 20% to 32% [P = .012]). During the pandemic, more institutions developed their own protocols for resource allocation (23% before to 51%; P < .001), and more programs created sharing arrangements to triage patients and equipment with other centers (31% to 57%; P < .001). Direct thrombin inhibitor use increased for both VA ECMO (13% to 18%; P = .025) and VV ECMO (12% to 24%; P = .005). Although cardiothoracic surgeons remained the primary cannulating proceduralists, VV ECMO cannulations performed by pulmonary and critical care physicians increased (13% to 17%; P = .046).

CONCLUSIONS

The Society of Thoracic Surgeons/Extracorporeal Life Support Organization collaborative survey indicated that the pandemic has affected ECMO practice. Further research on these ECMO strategies and lessons learned during the COVID-19 pandemic may be useful in future global situations.

Foundations of a Life Support Equipment Exchange Platform: ELSO Supplies

The ELSO Supplies Platform (Supplies.ELSO.org) was created out of Extracorporeal Membrane Oxygenation (ECMO) disposable product deficiency prior to and during the Coronavirus Disease 2019 (COVID-19) pandemic. This novel Platform supports Centers in obtaining disposables when alternative avenues are exhausted. Driven by the opportunity for increased patient care by using the product availability of the 962 ELSO centers worldwide was the motivation to form an efficient online supply sharing platform. The pandemic created by COVID-19, became a catalyst to further recognize the magnitude of the supply disruption on a global scale, impacting allocations and guidelines for institutions, practice, and patient care. Records kept on the platform website are helpful to industry by providing insights where difficulties exist in the supply chain for needed equipment. Yet, the common thread is awareness, how critical situations can stretch resources and challenge our resolve for best patient care. ELSO is proud to support member centers in these situations, by providing a means of attaining needed ECMO life support products to cover supply deficiencies.

Comparison of Evaluations for Heart Transplant Before Durable Left Ventricular Assist Device and Subsequent Receipt of Transplant at Transplant vs Nontransplant Centers

Importance

In 2020, the Centers for Medicare & Medicaid Services revised its national coverage determination, removing the requirement to obtain review from a Medicare-approved heart transplant center to implant a durable left ventricular assist device (LVAD) for bridge-to-transplant (BTT) intent at an LVAD-only center. The association between center-level transplant availability and access to heart transplant, the gold-standard therapy for advanced heart failure (HF), is unknown.

Objective

To investigate the association of center transplant availability with LVAD implant strategies and subsequent heart transplant following LVAD implant before the Centers for Medicare & Medicaid Services policy change.

Design, Setting, and Participants

A retrospective cohort study of the Society of Thoracic Surgeons Intermacs multicenter US registry database was conducted from April 1, 2012, to June 30, 2020. The population included patients with HF receiving a primary durable LVAD.

Exposures

LVAD center transplant availability (LVAD/transplant vs LVAD only).

Main Outcomes and Measures

The primary outcomes were implant strategy as BTT and subsequent transplant by 2 years. Covariates that might affect listing strategy and outcomes were included (eg, patient demographic characteristics, comorbidities) in multivariable models. Parameters for BTT listing were estimated using logistic regression with center-level random effects and for receipt of a transplant using a Cox proportional hazards regression model with death as a competing event.

Results

The sample included 22 221 LVAD recipients with a median age of 59.0 (IQR, 50.0-67.0) years, of whom 17 420 (78.4%) were male and 3156 (14.2%) received implants at LVAD-only centers. Receiving an LVAD at an LVAD/transplant center was associated with a 79% increased adjusted odds of BTT LVAD designation (odds ratio, 1.79; 95% CI, 1.35-2.38; P < .001). The 2-year transplant rate following LVAD implant was 25.6% at LVAD/transplant centers and 11.9% at LVAD-only centers. There was an associated 33% increased rate of transplant at LVAD/transplant centers compared with LVAD-only centers (adjusted hazard ratio, 1.33; 95% CI, 1.17-1.51) with a similar hazard for death at 2 years (adjusted hazard ratio, 0.99; 95% CI, 0.90-1.08).

Conclusions and Relevance

Receiving an LVAD at an LVAD-transplant center was associated with increased odds of BTT intent at implant and subsequent transplant receipt for patients at 2 years. The findings of this study suggest that Centers for Medicare & Medicaid Services policy change may have the unintended consequence of further increasing inequities in access to transplant among patients at LVAD-only centers.

Role of the mitral valve in left ventricular assist device pathophysiology

Functional mitral regurgitation (MR) in the setting of heart failure results from progressive dilatation of the left ventricle (LV) and mitral annulus. This leads to leaflet tethering with posterior displacement. Contrary to common assumptions, MR often does not resolve with LVAD decompression of the LV alone. The negative impact of significant (moderate-severe) mitral regurgitation in the LVAD setting is becoming better recognized in terms of its harmful effect on right heart function, pulmonary vascular resistance and hospital readmissions. However, controversies remain regarding the threshold for intervention and management. At present, there are no consensus indications for the repair of significant mitral regurgitation at the time of LVAD implantation due to the conflicting data regarding potential adverse effects of MR on clinical outcomes. In this review, we summarize the current understanding of MR pathophysiology in patients supported with LVAD and potential future management strategies.

Sex-based considerations for implementation of ventricular assist device therapy

Women with advanced heart failure receive advanced surgical therapies such as durable left ventricular assist device (LVAD) implantation or heart transplantation at a rate much lower compared to males. Reasons for this discrepancy remain largely unknown. Much of what is understood reflects outcomes of those patients who ultimately receive device implant or heart transplantation. Females have been shown to have a higher mortality following LVAD implantation and experience higher rates of bleeding and clotting phenomena and right ventricular failure. Beyond outcomes, the literature is limited in the identification of pre-operative factors that drive lower than expected LVAD implant rates in this population. More focused research is needed to define the disparities in advance heart failure therapy delivery in women and other underserved populations.

Impact of donor blood type on outcomes after prolonged allograft ischemic times

OBJECTIVE

The study objective was to determine the influence of allograft ischemic time on heart transplant outcomes among ABO donor organ types given limited prior reports of its survival impact.

METHODS

We identified 32,454 heart transplants (2000-2016) from the United Network for Organ Sharing database. Continuous and categoric variables were analyzed by parametric and nonparametric testing. Survival was determined using log-rank or Cox regression tests. Propensity matching adjusted for preoperative variables.

RESULTS

By comparing allograft ischemic time less than 4 hours (n = 6579) with 4 hours or more (n = 25,875), the hazard ratios for death at 15 years after prolonged ischemic time (≥4 hours) for blood types O, A, B, and AB were 1.106 (P < .001), 1.062 (P < .001), 1.059 (P = .062), and 1.114 (P = .221), respectively. Unadjusted data demonstrated higher mortality for transplantation of O versus non-O donor hearts for ischemic time 4 hours or more (hazard ratio, 1.164; P < .001). After propensity matching, O donor hearts continued to have worse survival if preserved for 4 hours or more (hazard ratio, 1.137, P = .008), but not if ischemic time was less than 4 hours (hazard ratio, 1.042, P = .113). In a matched group with 4 hours or more of ischemic time, patients receiving O donor organs were more likely to experience death from primary graft dysfunction (2.5% vs 1.7%, P = .052) and chronic allograft rejection (1.9% vs 1.1%, P = .021). No difference in death from primary graft dysfunction or chronic allograft rejection was seen with less than 4 hours of ischemic time (P > .150).

CONCLUSIONS

Compared with non-O donor hearts, transplantation with O donor hearts with ischemic time 4 hours or more leads to worse survival, with higher rates of primary graft dysfunction and chronic rejection. Caution should be practiced when considering donor hearts with the O blood type when anticipating extended cold ischemic times.

ECPR2: Expert Consensus on PeRcutaneous Cannulation for Extracorporeal CardioPulmonary Resuscitation

AIM

Extracorporeal cardiopulmonary resuscitation (ECPR) has emerged as a promising resuscitation strategy for select patients suffering from refractory out-of-hospital cardiac arrest (OHCA), though limited data exist regarding the best practices for ECPR initiation after OHCA.

METHODS

We utilized a modified Delphi process consisting of two survey rounds and a virtual consensus meeting to systematically identify detailed best practices for ECPR initiation following adult non-traumatic OHCA. A modified Delphi process builds content validity and is an accepted method to develop consensus by eliciting expert opinions through multiple rounds of questionnaires. Consensus was achieved when items reached a high level of agreement, defined as greater than 80% responses for a particular item rated a 4 or 5 on a 5-point Likert scale.

RESULTS

Snowball sampling generated a panel of 14 content experts, composed of physicians from four continents and five primary specialties. Seven existing institutional protocols for ECPR cannulation following OHCA were identified and merged into a single comprehensive list of 207 items. The panel reached consensus on 101 items meeting final criteria for inclusion: Prior to Patient Arrival (13 items), Inclusion Criteria (8), Exclusion Criteria (7), Patient Arrival (8), ECPR Cannulation (21), Go On Pump (18), and Post-Cannulation (26).

CONCLUSION

We present a list of items for ECPR initiation following adult nontraumatic OHCA, generated using a modified Delphi process from an international panel of content experts. These findings may benefit centers currently performing ECPR in quality assurance and serve as a template for new ECPR programs.

Determining optimal donor heart ischemic times in adult cardiac transplantation

Objectives

Unsupervised statistical determination of optimal allograft ischemic time (IT) on heart transplant outcomes among ABO donor heart types.

Methods

We identified 36,145 heart transplants (2000–2018) from the United Network for Organ Sharing database. Continuous and categorical variables were analyzed with parametric and nonparametric testing. Determination of IT cutoffs for survival analysis was performed using Contal and O'Quigley univariable method and Vito Muggeo multivariable segmented modeling.

Results

Univariable and multivariable IT threshold determination revealed a cutoff at about 3 h. The hourly increase in survival risk with ≥3 h IT is asymmetrically experienced at the early 90 days (hazard ratio [HR] = 1.29, p < .001) and up to 1‐year time point (HR = 1.16, p < .001). Beyond 1 year the risk of prolonged IT is less impactful (HR = 1.04, p = .022). Longer IT was associated with more postoperative complications such as stroke (2.7% vs. 2.3, p = .042), dialysis (11.6% vs. 9.1%, p < .001) and death from primary graft dysfunction (1.8% vs. 1.2%, p < .001). O blood type donor hearts with IT ≥ 3 h has significantly increased hourly mortality risk at 90 days (HR = 1.27, p < .001), 90 days to 1 year (HR = 1.22, p < .001) and >1 year (HR = 1.05, p = .041). For non‐O blood types with ≥3 h IT hourly mortality risk was increased at 90 days (HR = 1.33, p < .001), but not at 90 days to 1 year (HR = 1.09, p = .146) nor ≥1 year (HR = 1.08, p = .237).

Conclusions

The donor heart IT threshold for survival determined from unbiased statistical modeling occurs at 3 h. With longer preservation times, transplantation with O donor hearts was associated with worse survival.

Pulmonary Endarterectomy for Chronic Thromboembolic Pulmonary Hypertension: A STS Database Analysis

BACKGROUND

Chronic thromboembolic pulmonary hypertension (CTEPH) is optimally treated by pulmonary thromboendarterectomy (PEA). Treatment effectiveness has been evaluated principally using single-center series. Data from the Society of Thoracic Surgeons Adult Cardiac Surgery Database were used to evaluate a volume-outcomes relationship for PEA.

METHODS

Circulatory arrest procedures performed between 2012-2018 were identified through an STS-ACSD Participant User File. For descriptive purposes, total center procedural volume categories were computed: low (0-75^th percentile, <16); medium (76-95^th percentile, 16-100); high (>95^th percentile, >100). Mixed effect modeling was used to evaluate the effect of center procedural volume (modeled continuously) on operative mortality, adjusting for preoperative risk factors, with centers as a random effect.

RESULTS

There were 1,358 cases performed across 64 centers [n/N: low (49/172); medium (12/527); high (3/659)], with 42 centers performing <10 operations during the period. Procedural volume increased 2.6-fold between 2012-2018 (94 versus 339), with 79% of the change in volume accounted for by 4 centers. The mean (IQR) preoperative pulmonary artery systolic value was 74 mmHg (57-88), with no difference (p=0.55) by center volume categories. In unadjusted analysis, patients at high volume centers required fewer transfusions, had shorter ventilator and intensive care unit (ICU) duration, lower frequency of postoperative extracorporeal membrane oxygenation (ECMO), and trended lower mortality (2.1% vs 5.2%, p=0.051). Operative mortality was lower at higher volume centers (OR_adjusted,_{1-case-increase}: 0.997; CI95%: 0.994-1.0; p=0.025).

CONCLUSIONS

Most PEA procedures are performed among a small number of centers, with high-volume hospitals having favorable outcomes. These data suggest a potential role for PEA regionalization.

Human factors in ECLS - A keystone for safety and quality - A narrative review for ECLS providers

INTRODUCTION

Although the technology used for extracorporeal life support (ECLS) has improved greatly in recent years, the application of these devices to the patient is quite complex and requires extensive training of team members both individually and together. Human factors is an area that addresses the activities, contexts, environments, and tools which interact with human behavior in determining overall system performance.

HYPOTHESIS

Analyses of the cognitive behavior of ECLS teams and individual members of these teams with respect to the occurrence of human errors may identify additional opportunities to enhance safety in delivery of ECLS.

RESULTS

The aim of this article is to support health-care practitioners who perform ECLS, or who are starting an ECLS program, by establishing standards for the safe and efficient use of ECLS with a focus on human factor issues. Other key concepts include the importance of ECLS team leadership and management, as well as controlling the environment and the system to optimize patient care.

CONCLUSION

Expertise from other industries is extrapolated to improve patient safety through the application of simulation training to reduce error propagation and improve outcomes.

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.

Risk factors for heart transplant survival with greater than 5 h of donor heart ischemic time

OBJECTIVE

Implantation of donor hearts with prolonged ischemic times is associated with worse survival. We sought to identify risk factors that modulate the effects of prolonged preservation.

METHODS

Retrospective review of the United Network for Organ Sharing database (2000-2018) to identify transplants with >5 (n = 1526) or ≤5 h (n = 35,733) of donor heart preservation. In transplanted hearts preserved for >5 h, Cox-proportional hazards identify modifiers for survival.

RESULTS

Compared to ≤5 h, transplanted patients with >5 h of preservation spent less time in status 1B (76 ± 160 vs. 85 ± 173 days, p = .027), more commonly had ischemic cardiomyopathy (42.3% vs. 38.3%, p = .002), and less commonly received a blood type O heart (45.4% vs. 50.8%, p < .001). Longer heart preservation time was associated with a higher incidence of postoperative stroke (4.5% vs. 2.5%, p < .001), and dialysis (16.4% vs. 10.6%, p < .001). Prolonged preservation was associated with a greater likelihood of death from primary graft dysfunction (2.8% vs. 1.5%, p < .001) but there was no difference in death from acute (2.0% vs. 1.7%, p = .402) or chronic rejection (2.0% vs. 1.9%, p = .618). In transplanted patients with >5 h of heart preservation, multivariable analysis identified greater mortality with ischemic cardiomyopathy etiology (hazard ratio [HR] = 1.36, p < 0.01), pre-transplant dialysis (HR = 1.84, p < .01), pre-transplant extracorporeal membrane oxygenation (ECMO, HR = 2.36, p = .09), and O blood type donor hearts (HR = 1.35, p < .01).

CONCLUSION

Preservation time >5 h is associated with worse survival. This mortality risk is further amplified by preoperative dialysis and ECMO, ischemic cardiomyopathy etiology, and use of O blood type donor hearts.

Extracorporeal Cardiopulmonary Resuscitation for Refractory Out-of-Hospital Cardiac Arrest (EROCA): Results of a Randomized Feasibility Trial of Expedited Out-of-Hospital Transport

STUDY OBJECTIVE

Outcomes of extracorporeal cardiopulmonary resuscitation (ECPR) for out-of-hospital cardiac arrest depend on time to therapy initiation. We hypothesize that it would be feasible to select refractory out-of-hospital cardiac arrest patients for expedited transport based on real-time estimates of the 911 call to the emergency department (ED) arrival interval, and for emergency physicians to rapidly initiate ECPR in eligible patients.

METHODS

In a 2-tiered emergency medical service with an ECPR-capable primary destination hospital, adults with refractory shockable or witnessed out-of-hospital cardiac arrest were randomized 4:1 to expedited transport or standard care if the predicted 911 call to ED arrival interval was less than or equal to 30 minutes. The primary outcomes were the proportion of subjects with 911 call to ED arrival less than or equal to 30 minutes and ED arrival to ECPR flow less than or equal to 30 minutes.

RESULTS

Of 151 out-of-hospital cardiac arrest 911 calls, 15 subjects (10%) were enrolled. Five of 12 subjects randomized to expedited transport had an ED arrival time of less than or equal to 30 minutes (overall mean 32.5 minutes [SD 7.1]), and 5 were eligible for and treated with ECPR. Three of 5 ECPR-treated subjects had flow initiated in less than or equal to 30 minutes of ED arrival (overall mean 32.4 minutes [SD 10.9]). No subject in either group survived with a good neurologic outcome.

CONCLUSION

The Extracorporeal Cardiopulmonary Resuscitation for Refractory Out-of-Hospital Cardiac Arrest trial did not meet predefined feasibility outcomes for selecting out-of-hospital cardiac arrest patients for expedited transport and initiating ECPR in the ED. Additional research is needed to improve the accuracy of predicting the 911 call to ED arrival interval, optimize patient selection, and reduce the ED arrival to ECPR flow interval.

Fate of preoperative moderate mitral regurgitation following left ventricular assist device implantation

OBJECTIVE

We examined for improvements in preoperative moderate mitral regurgitation following continuous-flow left ventricular assist device (cfLVAD) implantation.

METHODS

From 2006 to 2020, 190 patients with moderate MR underwent cfVLAD implant without concomitant mitral valve (MV) surgery. Cardiac dimensions and contractility, as well as valve function, were assessed with an echocardiogram (echo) pre-cfLVAD, and at approximately 1 month post-cfLVAD. Outcomes were determined by retrospective chart review.

RESULTS

Median echo follow-up was 0.94 (0.53, 1.38) months. Residual significant moderate or greater MR was present in 30/190 (15.8%) on follow-up. Patients with significant residual MR had larger preoperative left ventricular internal diameters in diastole (74.4 ± 8.7 vs. 71.1.0 ± 9.1 mm, p = .034). Significant residual MR was associated with higher preoperative mean pulmonary artery pressures (OR = 1.055, p = .035) and pulmonary capillary wedge pressures (OR = 1.060, p = .034). Significant residual MR on echo was not associated with any survival difference (p = .325). The 1, 5, and 10 year survival were 89.9%, 55.2%, and 34.2%, respectively.

CONCLUSIONS

For patients with moderate MR undergoing LVAD implantation, the likelihood of significant residual MR is low and mitral intervention in this population is not recommended. However, select patients with larger preoperative left heart dimensions and pulmonary vascular pressures may be at risk for persistent residual MR.

Inflammatory Effects of Blood-Air Interface in a Porcine Cardiopulmonary Bypass Model

Cardiopulmonary bypass (CPB) causes a systemic inflammatory response syndrome (SIRS) associated with multiorgan injury. A model was developed to test whether a blood-air interface (BAI) in the CPB circuit causes blood element activation and inflammation. Ten healthy swine were placed on partial CPB for 2 hours via the cervical vessels and monitored for 96 hours postoperatively. Five pigs (control group) had minimal air exposure in the circuit, while five were exposed to a BAI simulating cardiotomy suction. There were no significant differences in bypass flow or hemodynamics between the groups. In the BAI group, there was an increase in hemolysis after bypass (plasma-free hemoglobin 5.27 ± 1.2 vs. 0.94 ± 0.8 mg/dl; p = 0.01), more aggressive platelet consumption (28% vs. 83% of baseline; p = 0.009), leukocyte consumption (71% vs. 107% of baseline; p = 0.02), and increased granulocyte CD11b expression (409% vs. 106% of baseline; p = 0.009). These data suggest the inflammatory pattern responsible for the CPB-SIRS phenomenon may be driven by blood-air interaction. Future efforts should focus on BAI-associated mechanisms for minimizing blood trauma and inflammation during CPB.

Adult Cardiac Surgery and the COVID-19 Pandemic: Aggressive Infection Mitigation Strategies Are Necessary in the Operating Room and Surgical Recovery

The COVID-19 pandemic necessitates aggressive infection mitigation strategies to reduce the risk to patients and healthcare providers. This document is intended to provide a framework for the adult cardiac surgeon to consider in this rapidly changing environment. Preoperative, intraoperative, and postoperative detailed protective measures are outlined. These are guidance recommendations during a pandemic surge to be used for all patients while local COVID-19 disease burden remains elevated.

Ramping Up Delivery of Cardiac Surgery During the COVID-19 Pandemic: A Guidance Statement From The Society of Thoracic Surgeons COVID-19 Task Force

The coronavirus disease 2019 (COVID-19) pandemic has had a profound global impact. Its rapid transmissibility has transformed healthcare delivery and forced countries to adopt strict measures to contain its spread. The vast majority of the United States cardiac surgical programs have deferred all but truly emergent/urgent operative procedures in an effort to reduce the burden on the healthcare system and to mobilize resources to combat the pandemic surge. While the number of COVID-19 cases continue to increase worldwide, the incidence of new cases has begun to decline in many North American cities. This "flattening of the curve" has prompted interest in reopening the economy, relaxing public health restrictions, and resuming nonurgent healthcare delivery. The following document provides a template whereby adult cardiac surgical programs may begin to ramp-up the care delivery in a deliberate and graded fashion as the COVID-19 pandemic burden begins to ease. "Resuscitating" the timely delivery of care is guided by three principles: (1) Collaborate to permit increased case volumes, balancing the clinical needs of patients awaiting surgical procedures with the local resources available within each healthcare system. (2) Prioritize patients awaiting elective procedures while proactively engaging all stakeholders, focusing on those with high-risk anatomy, changing/symptomatic clinical status, and, once these variables have been addressed, prioritizing by waiting times. (3) Reevaluate local conditions continuously to assess for any increase in admissions due to a recrudescence of cases, to assure adequate resources to care for patients, and to monitor in-hospital infectious transmissions to both patients and healthcare workers.

Adult cardiac surgery and the COVID-19 pandemic: Aggressive infection mitigation strategies are necessary in the operating room and surgical recovery

The COVID-19 pandemic necessitates aggressive infection mitigation strategies to reduce the risk to patients and healthcare providers. This document is intended to provide a framework for the adult cardiac surgeon to consider in this rapidly changing environment. Preoperative, intraoperative, and postoperative detailed protective measures are outlined. These are guidance recommendations during a pandemic surge to be used for all patients while local COVID-19 disease burden remains elevated.

Adult Cardiac Surgery During the COVID-19 Pandemic: A Tiered Patient Triage Guidance Statement

In the setting of the current novel coronavirus pandemic, this document has been generated to provide guiding statements for the adult cardiac surgeon to consider in a rapidly evolving national landscape. Acknowledging the risk for a potentially prolonged need for cardiac surgery procedure deferral, we have created this proposed template for physicians and interdisciplinary teams to consider in protecting their patients, institution, and their highly specialized cardiac surgery team. In addition, recommendations on the transition from traditional in-person patient assessments and outpatient follow-up are provided. Lastly, we advocate that cardiac surgeons must continue to serve as leaders, experts, and relevant members of our medical community, shifting our role as necessary in this time of need.

Adult cardiac surgery during the COVID-19 pandemic: A tiered patient triage guidance statement

In the setting of the current novel coronavirus pandemic, this document has been generated to provide guiding statements for the adult cardiac surgeon to consider in a rapidly evolving national landscape. Acknowledging the risk for a potentially prolonged need for cardiac surgery procedure deferral, we have created this proposed template for physicians and interdisciplinary teams to consider in protecting their patients, institution, and their highly specialized cardiac surgery team. In addition, recommendations on the transition from traditional in-person patient assessments and outpatient follow-up are provided. Lastly, we advocate that cardiac surgeons must continue to serve as leaders, experts, and relevant members of our medical community, shifting our role as necessary in this time of need.

Histidine-Tryptophan-Ketoglutarate Solution for Donor Heart Preservation Is Safe for Transplantation

BACKGROUND

Various solutions are used for donor heart preservation. We examined the outcomes in our heart transplant population where histidine-tryptophan-ketoglutarate (HTK) solution has been used for heart preservation since 2004.

METHODS

This was a retrospective review of the United Network for Organ Sharing (UNOS) database (2004-2016) comparing our heart transplant outcomes with other national centers. Propensity matching in a 1:3 ratio was performed to adjust for preoperative recipient variables.

RESULTS

After propensity matching comparing UNOS outcomes (n = 1080) with our institutional data (n = 360), there was no difference in matched preoperative variables. Donor hearts were similar for donor age, sex, donor-to-recipient size ratio, LVEF, and ischemic time. Our HTK cohort had a larger proportion with donor cardiac arrest (26.3% vs 6.1%, P < .001) and longer cardiac arrest duration (22.1 ± 16.0 vs 17.2 ± 14.0 minutes, P = .052). Our primary graft dysfunction (PGD) rate requiring mechanical support was 4.2% (n = 1). Postoperative mechanical support use for PGD included extracorporeal membrane oxygenation in 9 (60.0%), intraaortic balloon pump in 4 (26.7%), right ventricular assist device in 3 (20%), and biventricular assist device in 3 (20%). Overall survival at our institution was similar to the national average (P = .649). Survival at 1, 5, and 10 years with HTK was 92.2%, 81.3%, and 70.8%, and for the UNOS population was 91.6%, 80.3%, and 62.0%, respectively.

CONCLUSIONS

Use of HTK solution for donor hearts was associated with a low rate of severe PGD. Overall survival was not significantly different from other institutions using a variety of preservation solutions in the UNOS database during the same period. HTK solution is efficacious for preservation of donor hearts.

Aortic Valve Repair Versus Replacement Associated With Durable Left Ventricular Assist Devices

BACKGROUND

Aortic valve (AV) repair (AVr) using a central coaptation stitch or bioprosthetic AV replacement (AVR) are most commonly performed at the time of durable left ventricular assist device implant to address AV insufficiency (AI).

METHODS

Prospective data collection on 46 patients undergoing left ventricular assist device implant from 2007 through 2018 who received concomitant AVr (n = 40) or AVR (n = 6) was retrospectively analyzed to assess freedom from recurrent aortic insufficiency. Paired Wilcoxon rank-sum test was used to compare echocardiographic findings. Mantel-Cox statistics were used to analyze survival.

RESULTS

For AVr, central coaptation led to a mean decrease in AI severity by 2.1 ± 1.0 grades (P < .001). Three patients (7.5%) had recurrence of at least moderate AI by 3 years. In comparison, all patients in the AVR group had mild or less AI on subsequent follow-up. Success of AVr in downgrading AI severity was associated with a smaller aortic root diameter (P = .011) and sinotubular junction diameter (P = .003). An aortic root diameter greater than 3.5 cm was predictive of less improvement in AI severity compared with 3.5 cm or less (1.83 ± 1.03 versus 2.47 ± 0.80 grades of improvement; P = .038). Duration of cardiopulmonary bypass was 32 minutes longer and duration of aortic cross-clamp was 38 minutes longer for AVR versus AVr cohorts. No difference in 30-day (P = .418) or overall survival (P = .572) between the AVr and AVR groups was seen.

CONCLUSIONS

Aortic valve repair for addressing AI has a recurrence rate of 7.5% at 3 years. Success in downgrading AI is more likely with a smaller aortic root. No difference in survival was observed between AVr and AVR.

Simulation training enables emergency medicine providers to rapidly and safely initiate extracorporeal cardiopulmonary resuscitation (ECPR) in a simulated cardiac arrest scenario

BACKGROUND

Extracorporeal cardiopulmonaryresuscitation (ECPR) is emerging as a viable rescue strategy for refractory out-of-hospital cardiac arrest. In the U.S., limited training of emergency medicine providers is a barrier to widespread implementation.

AIMS

Test the hypothesis that emergency medicine physicians and nurses can acquire and retain the skills to rapidly and safely initiate ECPR using high-fidelity simulation.

STUDY DESIGN

Prospective interventional study.

SETTING

U.S. tertiary academic medical center.

SUBJECTS

Emergency medicine physicians and nurses with no prior ECPR/ECMO experience.

METHODS

Teams of three physicians and three nurses underwent a two-day ECPR training course including didactics, hands-on training, and simulation. Teams were videotaped initiating ECPR in a high-fidelity simulation scenario before and after simulation training. The primary outcome was the proportion of simulations in which full ECPR support was achieved within 30 min of patient arrival.

RESULTS

Five teams completed the entire study. Full ECPR support was achieved within 30 min of patient arrival in 11/15, 15/15, and 15/15 attempts at baseline (B), post-testing (PT) and 3-month post-testing (3-PT), respectively (p = 0.06). Intervals (mean ± sd) required to achieve full ECPR support at B, PT, and 3-PT were 25.8±5.3, 17.2±4.6, and 19.2±1.9 min respectively (p < 0.05 for B vs. PT and 3-PT).

CONCLUSION

High fidelity simulation training is effective in preparing emergency medicine physicians and nurses to rapidly and safely initiate ECPR in a simulated cardiac arrest scenario, and should be considered when implementing an ED-based ECPR program.

Right ventricular failure following left ventricular assist device implantation is associated with a preoperative pro-inflammatory response

Background

Systemic inflammation during implant of a durable left ventricular assist device (LVAD) may contribute to adverse outcomes. We investigated the association of the preoperative inflammatory markers with subsequent right ventricular failure (RVF).

Materials and methods

Prospective data was collected on 489 patients from 2003 through 2017 who underwent implantation of a durable LVAD. Uni- and multivariable correlation with leukocytosis was determined using linear and binary logistic regression. The population was also separated into low (< 10.5 K/ul, n = 362) and high (> 10.5 K/ul, n = 127) white blood cell count (WBC) groups. Mantel-Cox statistics was used to analyze survival data.

Results

Postop RVF was associated with a higher preop WBC (11.3 + 5.7 vs 8.7 + 3.1) and C-reactive protein (CRP, 5.6 + 4.4 vs 3.3 + 4.7) levels. Multivariable analysis identified an independent association between increased WBC preoperatively with increased lactate dehydrogenase (LDH, P < 0.001), heart rate (P < 0.001), CRP (P = 0.006), creatinine (P = 0.048), and INR (P = 0.049). The high WBC group was more likely to be on preoperative temporary circulatory support (17.3% vs 6.4%, P < 0.001) with a trend towards greater use of an intra-aortic balloon pump (55.9% vs 47.2%, P = 0.093). The high WBC group had poorer mid-term survival (P = 0.042).

Conclusions

Postop RVF is associated with a preoperative pro-inflammatory environment. This may be secondary to the increased systemic stress of decompensated heart failure. Systemic inflammation in the decompensated heart failure may contribute to RVF after LVAD implant.

Right ventricular function and residual mitral regurgitation after left ventricular assist device implantation determines the incidence of right heart failure

BACKGROUND

The effect of significant mitral regurgitation (MR) on outcomes after continuous flow left ventricular assist device (cfLVAD) implantation remains unclear.

METHODS

We performed a retrospective review of prospectively collected data from 159 patients with preoperative severe MR who underwent cfLVAD implantation (2003-2017). Two-step cluster analysis using the log-likelihood distance for post-cfLVAD implantation parameters, which included right ventricular (RV) dysfunction, MR severity, and tricuspid regurgitation (TR) severity. Post-cfLVAD implantation echocardiographic parameters were obtained within the first month.

RESULTS

Cluster analysis resulted in 3 groups. Group 1 (n = 67) had mild or less MR with moderate-severe RV dysfunction (RVD). Group 2 (n = 43) had moderate-severe MR with moderate-severe RVD. Group 3 (n = 49) had moderate MR with mild RVD. Group 2 had the largest proportion with Interagency Registry for Mechanically Assisted Circulatory Support score of 1 (30.2%) and 2 (41.9%). They were more likely to undergo temporary mechanical circulatory support (18.6%) and tricuspid valve procedure (62.8%). Group 2 had the highest rate of stroke (30.2%; P = .02), hemolysis (39.5%; P = .01), device thrombosis (30%; P = .01), and worst survival (46.5%; P = .01). Survival at 5 years for groups 1, 2, and 3 were 56.0%, 17.6%, and 55.8%. Regression analysis of the entire population showed that greater MR severity after cfLVAD was associated with RV failure (P < .05; odds ratio, 1.6) and RV assist device use (P = .09; odds ratio, 1.6). After excluding tricuspid valve repairs, MR severity had a positive correlation with TR severity (R = 0.33; P < .01).

CONCLUSIONS

After cfLVAD implantation, moderate-severe MR and RVD predicted RV failure. Patients with preoperative moderate-severe MR and TR coupled with moderate-severe RVD might benefit the most from mitral and tricuspid valve intervention.

Water-fat magnetic resonance imaging quantifies relative proportions of brown and white adipose tissues: ex-vivo experiments

Quantifying the amount of brown adipose tissue (BAT) within white adipose tissue (WAT) in human depots may serve as a target to combat obesity. We aimed to quantify proton density fat fraction (PDFF) of BAT and WAT in relatively pure and in mixed preparation using water–fat imaging. Three ex-vivo experiments were performed at 3 T using excised interscapular BAT and inguinal/subcutaneous WAT from mice. The first two experiments consisted of BAT and WAT in separate tubes, and the third used mixed preparation with graded quantities of BAT and WAT. To investigate the influence of partial volume on PDFF metrics, low (2.66  mm3) and high spatial resolution (0.55  mm3 acquired voxels) in two orthogonal three-dimensional sections were compared. The low-resolution acquisitions are corrected for T2* and multipeak lipid spectrum, thus considered “quantitative,” whereas the high-resolution acquisitions are not corrected but were performed to better spatially segment BAT from WAT zones. As potential BAT metrics, we quantified the average PDFF and the volume of tissue having PDFF ≤50% (VOLPDFF≤50%) based on the PDFF histogram. In the first experiment, the average PDFF of BAT was 23±6% and 21±7.6% and the average PDFF of WAT was 76±7% and 87±7% using high- and low-resolution techniques, respectively. A similar trend with excellent reproducibility in average PDFF of BAT and WAT was observed in the second experiment. In the third experiment over the four acquisitions, the BAT-dominant tube demonstrated lower PDFF (mean ± SD) of 55±2% than WAT-dominant (69±4%) and WAT-only tubes (88±4%). Estimating VOLPDFF≤50%, the BAT-dominant tube demonstrated higher volume of 0.26  cm3 than WAT-dominant (0.16  cm3) and WAT-only tubes (0.01  cm3). The presence of BAT exhibits a lower PDFF relative to WAT, thus allowing segmentation of low PDFF tissue for quantification of volume representative of BAT. Future studies will determine the clinical relevance of BAT volume within human depots.

Mechanical Circulatory Support for the Failing Fontan: Conversion to Assisted Single Ventricle Circulation—Preliminary Observations

Background:

Mechanical circulatory support (MCS) of a failing Fontan circulation remains challenging. We hypothesized that MCS can be provided by converting the Fontan circulation into a mechanically assisted single ventricle parallel circulation (MASVC).

Methods:

A porcine model of functionally univentricular circulation was created under cardiopulmonary bypass (CPB) by performing an atrial septectomy, tricuspid valvectomy, and interrupting antegrade pulmonary blood flow. A centrifugal flow pump was placed with inflow from the common atrium. Eight millimeter Dacron grafts anastomosed to the ascending aorta and main pulmonary artery supplied systemic (Qs) and pulmonary (Qp) blood flow. Ultrasonic flow probes were used to measure Qs and Qp after weaning from CPB. The Qp/Qs ratio was regulated using an adjustable clamp. Hemodynamic and laboratory data were recorded.

Results:

All four animals were successfully weaned from CPB onto the MASVC for a duration of two hours. Mechanically assisted single ventricle parallel circulation achieved satisfactory hemodynamics. As anticipated, the arterial oxygen saturation and partial pressure of oxygen in arterial blood were lower in the MASVC compared to baseline biventricular circulation. At the conclusion of the study, there was a trend towards a decrease in the mixed venous saturation with increasing oxygen extraction compared to the baseline. Serum lactate levels increased after weaning from CPB and did not return to baseline after two hours of support.

Conclusion:

Mechanically assisted single ventricle parallel circulation can be established in a single ventricle animal model. This strategy could potentially provide MCS of a single ventricle circulation. Studies with longer duration of support are required to assess adequacy of support and long-term sustainability.

Abstract 141: Increasing Storage Age of Transfused Red Blood Cell Units Is Not Associated with Cardiac Surgical Outcomes

Introduction: First-in, first-out institutional blood management practices are based on evidence associating increased risk of sequelae from exposure to older red blood cell (RBC) transfusions. Nonetheless, research to date within the setting of cardiac surgery has been limited by previously unmeasured confounding (i.e., use of leukoreduction, timing and volume transfused).

Hypothesis: After accounting for exposure to leukoreduction and the timing and volume of RBC units, older RBC units will not increase a patient’s odds of developing post-operative sequelae following cardiac surgery.

Methods: We reviewed 659 adult patients undergoing CABG and/or valve operations between January 1, 2008-December 31, 2015 at a tertiary center. During this time period, all RBCs given to cardiac surgery patients were leukoreduced. To address confounding by timing and volume of RBCs, we analyzed patients receiving 1 or 2 units of RBCs intraoperatively. Logistic regression was used to model the maximum storage age of RBCs against a composite endpoint (prolonged mechanical ventilation, pneumonia, renal failure, operative mortality). We further explored any differences when modeling age of RBCs as quintiles and dichotomously (≥14 vs. <14 days). We present our results using odds ratios and 95% confidence intervals.

Results: The average maximum storage age of RBCs ranged from 5 to 42 days (mean 20.8, sd: 7.0). The primary endpoint occurred among 122 (18.5%) subjects. There was neither a significant association between increasing age of RBCs and our composite endpoint (OR 1.0; 95% CI 0.98, 1.04), nor evidence of confounding in univariate analysis. These findings were qualitatively unchanged when modeling age of RBCs as quintiles (Figure; ptrend =0.50) or dichotomously (OR 1.6; 95% CI 0.88, 2.79).

Conclusion: In this single center study, we did not detect a significant adverse effect of increasing age of RBCs contrary to prior conclusions. Our findings suggest that current institutional RBC storage policies that prioritize distribution of older age RBC units may not adversely impact patient outcomes following cardiac surgery.

Kinetic estimated glomerular filtration rate and acute kidney injury in cardiac surgery patients

PURPOSE

To determine how a formula to estimate kinetically changing glomerular filtration rate (keGFR) relates to serum creatinine changes and to compare the discriminatory ability of keGFR to that of perioperative change in serum creatinine to predict acute kidney injury (AKI) and mortality.

MATERIALS AND METHODS

Retrospective cohort study at a single-tertiary-care Midwestern university hospital of 4022 patients admitted to the intensive care unit between January 2006 and January 2012 immediately after cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

Of 4022 patients, 1031 (25.6%) developed at least AKI stage 1 and 1106 (27.5%) developed AKI-min. Patients who developed AKI stage 1 or AKI-min had a greater decrease in keGFR, both by absolute amounts and by percentage. After adjusting for other factors with logistic regression, keGFR had good discrimination (c statistic = 0.787 and 0.749, respectively) in predicting AKI and operative mortality.

CONCLUSION

Despite no change in immediate perioperative serum creatinine levels, keGFR fell and this predicted subsequent AKI. Using keGFR enables identification of patients who, despite unchanged postoperative creatinine, incur clinically significant kidney injury based on reduction in GFR and increased mortality.

Conditions and procedures for in-hospital extracorporeal life support (ECLS) in cardiopulmonary resuscitation (CPR) of adult patients

The use of extracorporeal life support (ECLS) in cardiopulmonary resuscitation (CPR; ECPR) has been repeatedly published as non-randomized studies, mainly case series and case reports. The aim of this article is to support physicians, perfusionists, nurses and extracorporeal membrane oxygenation (ECMO) specialists who regularly perform ECPR or are willing to start an ECPR program by establishing standards for safe and efficient ECPR procedures. This article represents the experience and recommendations of physicians who provide ECPR routinely. Based on its survival and outcome rates, ECPR can be considered when determining the optimal treatment of patients who require CPR. The successful performance of ECLS cannulation during CPR is a life-saving measure and has been associated with improved outcome (including neurological outcome) after CPR. We summarize the general structure of an ECLS team and describe the cannulation procedure and the approaches for post-resuscitation care. The differences in hospital organizations and their regulations may result in variations of this model.