Faculty Bibliography

BACKGROUND:The Lung Allocation Score (LAS) significantly improved outcomes and waitlist mortality in lung transplantation. However, mortality remains high for the sickest waitlist candidates despite additional changes to allocation distance. Regulatory considerations of overhauling the current lung allocation system has met significant resistance, and would require years to implement. This study evaluates if a modest change to the current system by prioritization of only high-LAS lung transplant candidates would result in lowered waitlist mortality. METHODS:The Thoracic Simulated Allocation Model was used to evaluate all lung transplant candidates and donor lungs recovered between July 1, 2009 and June 30, 2011. Current lung allocation rules (initial offer within 250 nautical-mile radius for ABO-identical then compatible offers) were run. Allocation was then changed for only patients with an LAS≥50 (high-LAS) to be prioritized within a 500 nautical-mile radius with no stratification between ABO-identical and compatible offers. Ten iterations of each model were run. Primary endpoints were waitlist mortality and post-transplant 1-year survival. RESULTS:6,538 waitlist candidates and transplant recipients were evaluated per iteration, for a total of 130,760 simulated patients. Compared with current allocation, the adjusted model had a 23.3% decrease in waitlist mortality. Post-transplant 1-year survival was minimally affected. CONCLUSIONS:Without overhauling the entire system, simple prioritization changes to the allocation system for high-LAS candidates may lead to decreased waitlist mortality and increased organ utilization. Importantly, these changes do not appear to lead to clinically significant changes in post-transplant 1-year survival.

Thoracic organs from Hepatitis C virus (HCV) positive donors are not commonly used for transplantation. The development of direct-acting antivirals (DAA) for HCV treatment has led to renewed interest in using HCV-positive organs. We evaluated HCV transmission rates, viremia clearance, and short-term outcomes in HCV-negative patients who received HCV-positive thoracic organs at our institution. From January 1, 2018 to May 31, 2019, 38 patients underwent HCV-positive thoracic organ transplantation (16 lungs and 22 hearts). Heart recipients were started on glecaprevir/pibrentasvir, a pangenotypic DAA, when they developed HCV viremia. Lung recipients were empirically started on glecaprevir/pibrentasvir within the first three post-transplant days. The primary outcome was cure of HCV defined as sustained virologic response at 12 weeks (SVR12). All heart recipients developed HCV viremia with median initial viral load of 64,565 IU/mL (interquartile range: 1660 to 473,151). The median time from DAA initiation to viremia clearance was 19 days (confidence interval: 15-27 days). 11 out of 16 (68.8%) lung recipients developed HCV viremia with median initial viral load of 26 IU/mL (interquartile range: 15 to 143). The median time from DAA initiation to viremia clearance was 10 days (confidence interval: 6-17 days). 5 out of 16 (31.3%) lung recipients never became viremic. All patients demonstrated SVR12. Thoracic organ transplantation from HCV viremic donors is safe with excellent short-term survival. Early initiation of HCV treatment results in rapid viremia clearance and SVR12. Long-term outcomes and optimal timing of DAA initiation remains to be determined.

Introduction: Coronavirus disease 2019 (COVID-19) remains a worldwide pandemic with some patients requiring escalation to venovenous extracorporeal membrane oxygenation (VV-ECMO). Our ECMO Program placed 30 adult COVID-19 patients on VV ECMO within six weeks. This surge required immediate assessment of our program's current structure and resources and rapid execution of an emergency response plan.
Method(s): Additional hardware and disposable supplies were acquired through capital purchases, rental agreements, collaboration with neighboring institutions, and repurposing of existing equipment. All patients were ultimately cohorted to one location. Our Perfusion team implemented a new staffing schedule to increase ECMO coverage. A condensed COVID ECMO course was created to increase the number of ECMO-trained nurses. Existing bedside cannulation carts and an exchange process with Central Supply allowed for multiple cannulations in various locations. A daily report was distributed to ECMO and hospital leadership to promote effective communication and ensure transparency of ECMO capacity.
Result(s): As of August 20th, 27 patients survived to ECMO decannulation and 23 patients survived to hospital discharge. Five patients remain hospitalized. During the surge, we averaged 13 patients on ECMO per day, which was an increase over our baseline of 3.5 patients per day for the six months preceding COVID-19.
Conclusion(s): We conclude that it is possible to safely expand ECMO capacity during a pandemic. This requires proper planning and reallocation of resources as necessary. Our navigation of the surge was aided by our existing program processes and the generosity of neighboring ECMO programs and our industry partners

Study: Despite advances in design and hemocompatibility, pump thrombosis remains a significant cause of morbidity for patients implanted with durable left ventricular assist devices (LVAD). Pharmacologic fibrinolysis may be preferred as initial therapy because it obviates a surgical procedure. Yet, it historically has been associated with a significant risk of secondary intracerebral hemorrhage (ICH).
Method(s): We implemented a novel protocol to treat HVAD pump thrombosis and minimize risk of ICH that consisted of the following: initiation of a non-titrating heparin infusion at 500 units/hr; normalization of international normalized ratio (INR) by giving a flat dose of 1,000 units of four-factor prothrombin complex concentration (4F-PCC); and administration of alteplase as a 10 mg bolus followed by 40 mg given over 3 hours.
Result(s): Two patients underwent treatment with the above protocol for presumed HVAD pump thrombosis based on clinical signs of hemolysis and elevations of power on log-file analysis. One patient was 2 months from HVAD implant and the other 13 months. Both patients had subtherapeutic INR in the preceding weeks. Following administration of alteplase, log-file analysis demonstrated immediate resolution of power elevations (Fig. 1). Both patients had a subsequent rise in power requiring repeat alteplase dosing. No bleeding or thrombotic events occurred with treatment. One patient underwent heart transplant a month after treatment and is doing well; the second patient is stable on HVAD support 4 months following alteplase. Combining 4F-PCC to temporarily normalize the INR with repeat dosing of alteplase was effective at resolving HVAD pump thrombosis without bleeding complications and should be investigated further

Study: The Impella (Abiomed, Danvers, MA) ventricular support system is a family of temporary mechanical circulatory support devices designed to treat patients with cardiogenic shock. These devices include the percutaneously implanted 2.5/CP and the surgically implanted 5.0/LD. Data to assess adverse outcomes and help guide decision-making between Impella CP and 5.0/LD devices is limited. The purpose of this study was to compare the characteristics and clinical outcomes between Impella CP and 5.0/LD at our institution.
Method(s): From December 1, 2014 to October 31, 2019 a total of 117 patients underwent Impella implantation regardless of indication or device type. Of these, 82 patients were supported for greater than 24-hour duration. Baseline patient characteristics and outcomes were reviewed retrospectively. Groups were stratified based on either initial Impella CP or 5.0/LD placement and their clinical outcomes compared.
Result(s): Impella CP was implanted in 56 patients (median age: 60.5 years, male 71.4%) and Impella 5.0/LD (median age: 65.5 years, male 84.6%) were implanted in 26 patients. Regardless of the indication for Impella placement, 24 patients with Impella CP required additional mechanical support and were upgraded to either Impella 5.0/LD or extracorporeal membrane oxygenation (ECMO) (p=0.005). Patients with Impella CP had increased incidence of hemolysis defined as the presence of gross hematuria and elevated lactated dehydrogenase (Table 1). Patients with Impella 5.0/LD were more likely to survive from Impella and survive to discharge. Data from this study suggests that Impella 5.0/LD may have a more favorable device-specific adverse event profile compared to Impella CP

BACKGROUND:The Impella (Abiomed) ventricular support system is a family of temporary mechanical circulatory support (MCS) devices used to treat patients with cardiogenic shock, acute cardiogenic decompensation, and for high-risk percutaneous or surgical revascularization. These devices include the percutaneously implanted 2.5/cardiac power (CP) and the surgically implanted 5.0/left direct (LD). Despite the beneficial effects and increased usage of these devices, data to assess adverse outcomes and guide clinician decision-making between the Impella CP and 5.0/LD are limited. METHODS:This is a retrospective analysis of 91 consecutive patients who required at least 24 h of Impella support, from January 1, 2015 to December 31, 2019. Groups were stratified based on either initial Impella CP or 5.0/LD placement. Clinical outcomes and in-hospital complications were compared. RESULTS:Impella CP was implanted in 66 patients (mean age: 61 ± 15 years, male 71.2%) and Impella 5.0/LD was implanted in 25 patients (mean age: 62 ± 9 years, male 84.0%). There was greater stability of device position (p = .033), less incidence of hemolysis (p < .001), and less frequent need for additional MCS (p = .001) in patients implanted with the Impella 5.0/LD compared with Impella CP in this study cohort. Patients with Impella 5.0/LD were more likely to survive from Impella and survive to discharge. CONCLUSIONS:This study suggests that for patients who require temporary MCS for more than 24 h, the Impella 5.0/LD may have a more favorable device-specific adverse profile compared with the Impella CP.