Characterizing Adaptive Changes and Patient Survival After 2018 Donor Allocation Restructuring: A UNOS Database Analysis.

PURPOSE: We sought to characterize adaptive changes to the revised United Network for Organ Sharing donor heart allocation policy and estimate long-term survival trends for heart transplant (HTx) recipients. METHODS: Patients listed for HTx between October 17, 2013 and September 30, 2021 were identified from the United Network for Organ Sharing database, and stratified into pre- and postpolicy revision groups. Subanalyses were performed to examine trends in device utilization for extracorporeal membranous oxygenation (ECMO), durable left ventricular assist device (LVAD), intra-aortic balloon pump (IABP), microaxial support (Impella), and no mechanical circulatory support (non-MCS). Survival data post-HTx were fitted to parametric distributions and extrapolated to 5 years. RESULTS: We identified 27,523 HTx waitlist candidates during the study period, most of whom (n = 16,376) were waitlisted in the prepolicy change period. Overall, 19,554 patients underwent HTx during the study period (pre: 12,037 and post: 7517). Listings increased after the policy change for ECMO ( P < 0.01), Impella ( P < 0.01), and IABP ( P < 0.01) patients. Listings for LVAD ( P < 0.01) and non-MCS ( P < 0.01) patients decreased. HTx increased for ECMO ( P < 0.01), Impella ( P < 0.01), and IABP ( P < 0.01) patients after the policy change and decreased for LVAD ( P < 0.01) and non-MCS ( P < 0.01) patients. Waitlist survival increased for the overall ( P < 0.01), ECMO ( P < 0.01), IABP ( P < 0.01), and non-MCS ( P < 0.01) groups. Waitlist survival did not differ for the LVAD ( P = 0.8) and Impella ( P = 0.1) groups. Post-transplant survival decreased for the overall ( P < 0.01), LVAD ( P < 0.01), and non-MCS ( P < 0.01) populations. CONCLUSIONS: Allocation policy revisions have contributed to greater utilization of ECMO, Impella, and IABP, decreased utilization of LVADs and non-MCS, increased waitlist survival, and decreased post-HTx survival.

Assessing donor-recipient size metrics for heart transplant outcomes: UNOS database analysis.

STUDY: There is no widely accepted donor to recipient size-match metric to predict outcomes in cardiac transplant. The predictive ability of size-match metrics has not been studied when recipients are stratified by heart failure etiology. We sought to assess the performance of commonly used size metrics to predict survival after heart transplant, accounting for restrictive versus non-restrictive pathology. METHODS: The UNOS registry was queried from 2000 to 2017 for all primary isolated heart transplants. Donor-recipient ratios were calculated for commonly used size metrics and their association with survival was assessed using continuous, nonlinear analysis. RESULTS: 29 817 patients were identified. Height (P < .001), predicted heart mass (PHM) (P = .003), ideal body weight (IBW) (P < .001) and body mass index (BMI) (P = .003) ratios were significantly associated with survival, while weight and body surface area (BSA) ratios were not. When stratified, only BMI ratio retained significance for both restrictive (P = .051) and non-restrictive (P = .003) subsets. Recipients with restrictive etiology had increased risk of mortality with both a lower and higher BMI ratio. CONCLUSIONS: While many metrics show association with survival in the non-restrictive subset, BMI is the only metric that retains significance in the restrictive subset. Recipients with restrictive and non-restrictive etiologies of heart failure tolerate size mismatch differently.

Extracorporeal life support and cardiopulmonary bypass for central airway surgery: A systematic review.

BACKGROUND: Major airway surgery can pose a complex problem to perioperative central airway management. Adjuncts to advanced ventilation strategies have included cardiopulmonary bypass, veno-arterial, or veno-venous extracorporeal life support. We performed a systematic review to assess the existing evidence utilizing these strategies. METHODS: An electronic search was conducted to identify studies written in English reporting the use of extracorporeal life support (ECLS) during central airway surgery. Thirty-six articles consisting of 78 patients were selected and patient-level data were analyzed. RESULTS: Median patient age was 47 [IQR: 34-53] and 59.0% (46/78) were male. Indications for surgery included central airway or mediastinal cancer in 57.7% (45/78), lesion or injury in 15.4% (12/78), and stenosis in 12.8% (10/78). Support was initiated pre-operatively in 9.9% (7/71) and at the time of induction in 55.3% (42/76). It was most commonly used at the time of tracheal resection/repair [93.2% (68/73)], intubation of the tracheal stump [94.4% (68/72)], and re-anastomosis [94.2% (65/69)]; 13.7% (10/73) patients were supported post-operatively. The most commonly performed surgery was tracheal repair or resection in 70.3% (52/74). Median hospital stay was 12 [8, 25] days and in-hospital mortality was 7.9% (6/76). There was no significant difference in survival between the three groups (p = .54). CONCLUSIONS: Extracorporeal membrane oxygenation offers versatility in timing, surgical approach, and ECLS runtime that makes it a viable addition to the surgical armamentarium for treating complex central airway pathologies.

Continuous-flow LVAD exchange to a different pump model: Systematic review and meta-analysis of the outcomes.

Despite improved outcomes of modern continuous-flow left ventricular assist devices (CF-LVADs), device exchange is still needed for various indications. While the majority of CF-LVADs are exchanged to the same model, exchange to a different pump model is occasionally warranted. In this meta-analysis, we sought to consolidate the existing evidence to better elucidate the indications and outcomes in these cases. A comprehensive systematic search of adult patient cohorts who underwent CF-LVAD exchange to a different CF-LVAD model was performed. Study-level data from 10 studies comprising 98 patients were extracted and pooled for analysis. Mean patient age was 58 (95% CI: 48-65) and 81% were male. Indication for initial CF-LVAD was ischemic cardiomyopathy in 45% (34-57). Initial device was HeartMate II LVAD (HMII) in 93 (94.9%) and HeartWare HVAD (HW) in 5 (5.1%) patients. After mean CF-LVAD support time of 18.8 (15.2-22.4) months, exchange indications included thrombosis in 71% (43-89), infection in 21% (8-47) and device malfunction in 12% (7-21). HMII to HW exchange occurred in 53 (54.1%) patients, HMII to HeartMate III (HM3) in 32 (32.7%), and HM II to either HW or HM3 in 13 (13.2%) patients. Postoperatively, right ventricular assist device was required in 16% (8-32). Overall, 20% (8-40) of patients experienced a stroke, while HW patients had a significantly higher stroke incidence than HM3 patients (HW: 21% (8-47) vs. HM3: 5% (1-24), P < .01). Overall 30-day mortality was 10% (6-17), while HW had a significantly worse 30-day mortality than HM3 (HW: 13% (7-24) vs. HM3: 5% (1-24), P = .03). Following device exchange from a different CF-LVAD model, HM3 is associated with lower stroke and higher survival when compared to HW.

Clinical implications of LDH isoenzymes in hemolysis and continuous-flow left ventricular assist device-induced thrombosis.

Pump-induced thrombosis continues to be a major complication of continuous-flow left ventricular assist devices (CF-LVADs), which increases the risks of thromboembolic stroke, peripheral thromboembolism, reduced pump flow, pump failure, cardiogenic shock, and death. This is confounded by the fact that there is currently no direct measure for a proper diagnosis during pump support. Given the severity of this complication and its required treatment, the ability to accurately differentiate CF-LVAD pump thrombosis from other complications is vital. Hemolysis measured by elevated lactate dehydrogenase (LDH) enzyme levels, when there is clinical suspicion of pump-induced thrombosis, is currently accepted as an important metric used by clinicians for diagnosis; however, LDH is a relatively nonspecific finding. LDH exists as five isoenzymes in the body, each with a unique tissue distribution. CF-LVAD pump thrombosis has been associated with elevated serum LDH-1 and LDH-2, as well as decreased LDH-4 and LDH-5. Herein, we review the various isoenzymes of LDH and their utility in differentiating hemolysis seen in CF-LVAD pump thrombosis from other physiologic and pathologic conditions as reported in the literature.

Serotonin syndrome following left ventricular assist device implantation: A report and institution-specific strategy for prevention.

Serotonin syndrome is a potentially lethal complication of antidepressant therapy. Cardiac surgical patients are at particularly high risk of serotonin syndrome due to the prevalence of depression in patients with advanced cardiac disease, many of whom receive multiple serotonergic agents in the perioperative period. Here, we describe a case of postoperative serotonin syndrome following methylene blue administration for perioperative vasoplegia during left ventricular assist device implantation. We additionally describe an institution-specific strategy to minimize future occurrences of serotonin syndrome in this high-risk population. .

Temporary support strategies for cardiogenic shock: extracorporeal membrane oxygenation, percutaneous ventricular assist devices and surgically placed extracorporeal ventricular assist devices.

The majority of clinical pathways and paradigms utilized in the treatment and management of cardiogenic shock with temporary mechanical circulatory support (MCS) are largely based on individual physician intuition and ad hoc problem-solving. Substantial mortality gains in the acute myocardial infarction cardiogenic shock (AMI-CS) population were observed with the reported outcomes of the SHOCK trial in 1999 compared to previous populations with AMI-CS. Nonetheless even in the age of percutaneous coronary intervention (PCI) of the infarct related artery, survival rates continue to be only approximately 50%. The conventional focus since the SHOCK trial has centered on revascularization strategies and the subsequent medical management of these patients post-PCI with ever diminishing returns. Perhaps we have hit the "glass ceiling" with current strategies and it is time to explore novel strategies to salvage not only the heart but more importantly the patient and potentially more of both. Going forward, researchers need to focus on developing a systematic approach to problem solving in utilizing MCS for patients with cardiogenic shock. Effective methodologies that are evidence based will help physicians in their decision-making when considering temporary MCS for patients.

Prospective analysis of bleeding events in left ventricular assist device patients.

BACKGROUND: Bleeding is a major cause of morbidity in patients with continuous flow left ventricular assist devices (LVADs). We sought to identify clinical predictors of bleeding within the first year of LVAD implantation. METHODS: A prospective study was performed on 30 patients with HeartMate II implantation at the University of Rochester Medical Center, Rochester, New York, United States. Blood was collected within 1 week before implantation, and at 1, 3, and 30 ± 10 days after implantation. Blood samples were analyzed for prothrombin time (PT), international normalized ratio (INR), von Willebrand factor (vWF) activity, vWF antigen, vWF multimers, collagen binding assay, factor VIII, and epinephrine closure time. The first bleeding event within 1 year of implantation was recorded. RESULTS: There were 17 (57%) patients with a bleeding event. The cumulative incidence of bleeding was 50% at 304 days. Age at the time of LVAD implantation was associated with higher risk of bleeding (hazard ratio (HR) = 1.05, 95% confidence interval (CI) = 1.01-1.10, p = 0.013). Higher baseline INR was also associated with increased risk of bleeding after adjusting for age at the time of implant (HR = 6.58, 95% CI = 1.21-35.70, p = 0.028). The bleeders and non-bleeders had similar hemostatic markers at all four time points. Prior to LVAD, mean epinephrine closure time was similar between bleeders and non-bleeders. However, post LVAD measurement of epinephrine, closure time was frequently limited by platelet clumping. CONCLUSION: Older age and baseline INR are associated with higher risk of bleeding in LVAD patients. Platelet clumping may suggest underlying platelet dysfunction and associated high risk of bleeding.

Right Ventricular Assist Device Configuration for Remote Decannulation.

Preoperative risk factors, intraoperative fluid shifts, and transfusions place patients at increased risk for right ventricular failure during left ventricular assist device implantation. Despite aggressive use of inotropes and pulmonary vasodilators, in severe cases of RV failure, a right ventricular assist device may be required. For the past several years, we have been implanting right ventricular assist devices in the presented configuration, allowing less invasive removal without sternotomy. The method is presented herein.

Long-term total cardiac support in a Fontan-type circulation with HeartMate II left ventricular assist device.

Interest in utilizing long-term mechanical circulatory support for Fontan-type circulation has been high. Unfortunately, so far such attempts have not been successful. Herein, we are presenting the first case of an individual with biventricular heart failure and Fontan-type circulation on long-term mechanical circulatory support with a continuous-flow left ventricular assist device.

Repair of pectus excavatum during HeartMate II left ventricular assist device placement.

Pectus excavatum deformity often remains clinically asymptomatic even in cases of a severely diminished thoracic volume and frequently remains uncorrected. In the patient population that requires left ventricular assist device (LVAD) placement, a diminished thoracic volume can be problematic and lead to significant challenges in pump and outflow cannula positioning. Here we present a case of pectus excavatum correction during LVAD placement to show that this deformity can be successfully addressed with minimal, if any, additional operative risk at the time of LVAD implant.

Imaging of mechanical cardiac assist devices.

Diagnostic imaging plays an important role in the assessment of patients with mechanical cardiac assist devices. Therefore, it is important for radiologists to be familiar with the basic components, function, and radiographic appearances of these devices in order to appropriately diagnose complications. The purpose of this pictorial essay is to review indications, components, normal imaging appearances, and complications of surgically and percutaneously implanted ventricular assist devices, intra-aortic balloon pumps, and cardiac meshes.