Epidemiology, management, and clinical outcomes of extrapulmonary Mycobacterium abscessus complex infections in heart transplant and ventricular assist device recipients.

Nontuberculous mycobacteria are emerging pathogens, yet data on the epidemiology and management of extrapulmonary nontuberculous mycobacteria infections in orthotopic heart transplantation (OHT) and ventricular assist device (VAD) recipients are scarce. We retrospectively reviewed records of OHT and VAD recipients who underwent cardiac surgery at our hospital and developed Mycobacterium abscessus complex (MABC) infection from 2013 to 2016 during a hospital outbreak of MABC linked to heater-cooler units. We analyzed patient characteristics, medical and surgical management, and long-term outcomes. Ten OHT patients and 7 patients with VAD developed extrapulmonary M. abscessus subspecies abscessus infection. The median time from presumed inoculation during cardiac surgery to the first positive culture was 106 days in OHT and 29 days in VAD recipients. The most common sites of positive cultures were blood (n = 12), sternum/mediastinum (n = 8), and the VAD driveline exit site (n = 7). The 14 patients diagnosed when alive received combination antimicrobial therapy for a median of 21 weeks, developed 28 antibiotic-related adverse events, and underwent 27 surgeries. Only 8 (47%) patients survived longer than 12 weeks after diagnosis, including 2 patients with VAD who experienced long-term survival after an explantation of infected VADs and OHT. Despite aggressive medical and surgical management, OHT and VAD patients with MABC infection experienced substantial morbidity and mortality.

A textile-reinforced composite vascular graft that modulates macrophage polarization and enhances endothelial cell migration, adhesion and proliferation in vitro.

At the present time, there is no successful off-the-shelf small-caliber vascular graft (<6 mm) for the repair or bypass of the coronary or carotid arteries. In this study, we engineer a textile-reinforced hydrogel vascular graft. The textile fibers are circularly knitted into a flexible yet robust conduit to serve as the backbone of the composite vascular graft and provide the primary mechanical support. It is embedded in the hydrogel matrix which seals the open structure of the knitted reinforcement and mediates cellular response toward a faster reendothelialization. The mechanical properties of the composite vascular graft, including bursting strength, suture retention strength and radial compliance, significantly surpass the requirement for the vascular graft application and can be adjusted by altering the structure of the textile reinforcement. The addition of hydrogel matrix, on the other hand, improves the survival, adhesion and proliferation of endothelial cells in vitro. The composite vascular graft also enhances macrophage activation and upregulates M1 and M2 related gene expression, which further improves the endothelial cell migration that might favor the reendothelialization of the vascular graft. Taken together, the textile-reinforced hydrogel shows it potential to be a promising scaffold material to fabricate a tissue engineered vascular graft.

Complex repolarization dynamics in ex vivo human ventricles are independent of the restitution properties.

AIMS: The mechanisms of transition from regular rhythms to ventricular fibrillation (VF) are poorly understood. The concordant to discordant repolarization alternans pathway is extensively studied; however, despite its theoretical centrality, cannot guide ablation. We hypothesize that complex repolarization dynamics, i.e. oscillations in the repolarization phase of action potentials with periods over two of classic alternans, is a marker of electrically unstable substrate, and ablation of these areas has a stabilizing effect and may reduce the risk of VF. To prove the existence of higher-order periodicities in human hearts. METHODS AND RESULTS: We performed optical mapping of explanted human hearts obtained from recipients of heart transplantation at the time of surgery. Signals recorded from the right ventricle endocardial surface were processed to detect global and local repolarization dynamics during rapid pacing. A statistically significant global 1:4 peak was seen in three of six hearts. Local (pixel-wise) analysis revealed the spatially heterogeneous distribution of Periods 4, 6, and 8, with the regional presence of periods greater than two in all the hearts. There was no significant correlation between the underlying restitution properties and the period of each pixel. CONCLUSION: We present evidence of complex higher-order periodicities and the co-existence of such regions with stable non-chaotic areas in ex vivo human hearts. We infer that the oscillation of the calcium cycling machinery is the primary mechanism of higher-order dynamics. These higher-order regions may act as niduses of instability and may provide targets for substrate-based ablation of VF.

Invasive Mycobacterium abscessus Complex Infection After Cardiac Surgery: Epidemiology, Management, and Clinical Outcomes.

BACKGROUND: We recently mitigated a clonal outbreak of hospital-acquired Mycobacterium abscessus complex (MABC), which included a large cluster of adult patients who developed invasive infection after exposure to heater-cooler units during cardiac surgery. Recent studies have detailed Mycobacterium chimaera infections acquired during cardiac surgery; however, little is known about the epidemiology and clinical courses of cardiac surgery patients with invasive MABC infection. METHODS: We retrospectively collected clinical data on all patients who underwent cardiac surgery at our hospital and subsequently had positive cultures for MABC from 2013 through 2016. Patients with ventricular assist devices or heart transplants were excluded. We analyzed patient characteristics, antimicrobial therapy, surgical interventions, and clinical outcomes. RESULTS: Ten cardiac surgery patients developed invasive, extrapulmonary infection from M. abscessus subspecies abscessus in an outbreak setting. Median time from presumed inoculation in the operating room to first positive culture was 53 days (interquartile range [IQR], 38-139 days). Disseminated infection was common, and the most frequent culture-positive sites were mediastinum (n = 7) and blood (n = 7). Patients received a median of 24 weeks (IQR, 5-33 weeks) of combination antimicrobial therapy that included multiple intravenous agents. Six patients required antibiotic changes due to adverse events attributed to amikacin, linezolid, or tigecycline. Eight patients underwent surgical management, and 6 patients required multiple sternal debridements. Eight patients died within 2 years of diagnosis, including 4 deaths directly attributable to MABC infection. CONCLUSIONS: Despite aggressive medical and surgical management, invasive MABC infection after cardiac surgery caused substantial morbidity and mortality. New treatment strategies are needed, and compliance with infection prevention guidelines remains critical.

Successfully sharing the sandbox: A perspective on combined DCD liver and heart donor procurement.

Donation after circulatory death (DCD) heart transplantation is currently being performed in the United States as part of a clinical trial. As with all donor procurements, effective coordination between all involved teams is vital for successful organ recovery and maximal utilization of donor organs. The current discussion relays a viewpoint on combined DCD liver and heart donor procurement. Key issues highlighted include the vital importance of donor warm ischemia time (DWIT) on outcome for both recipients as well as issues pertaining to DWIT that may arise when performing combined DCD liver and heart donor procurement.

Stroke risk following implantation of current generation centrifugal flow left ventricular assist devices.

BACKGROUND AND AIM: Stroke remains a significant complication of left ventricular assist device (LVAD) therapy. We performed a single-center retrospective study evaluating patients undergoing first-time HeartWare HVAD (Medtronic Inc) or HeartMate 3 (Abbott Inc) implantation from September 2009-February 2018. METHODS: Exclusion criteria were age <18 and preoperative ECMO. The primary endpoint was stroke-free survival. Stroke was defined as new neurological deficits persisting >24 hours with corresponding radiographic evidence. Risk factors evaluated included demographics, medical comorbidities, heart failure etiology, LVAD indication, INTERMACS profile, and device type. Univariate predictors (P < .15) and variables clinically suspected to raise stroke risk were entered in a multivariate hazard regression model, specified using backward selection of covariates and accounting for competing risks of transplant/LVAD exchange. RESULTS: A total of 163 HVAD and 84 HM3 patients were analyzed. Median follow up (until death, censoring for transplant/LVAD removal, or end of follow up) was 1.2 years in HVAD patients and 1.4 years in HM3 patients. Stroke occurred in 24 HVAD patients (15 ischemic, 9 hemorrhagic) and 6 HM3 patients (4 ischemic, 2 hemorrhagic). One-year stroke-free survival was 76.8% for HVAD and 84.3% for HM3. Thirty-day mortality following stroke was 41.7% for HVAD and 66.7% for HM3; 54.2% of HVAD strokes were disabling compared to 83.3% of HM3 strokes. Age, LVAD indication, and device type were associated (P < .15) with stroke on univariate analysis. On multivariate analysis, the HVAD was associated with significantly higher stroke risk (hazard ratio, 2.57; 95% confidence interval, 1.02-6.44; P = .045). CONCLUSIONS: Different LVAD models appear to be associated with significantly different stroke risks.

Percutaneous Intervention for Left Ventricular Assist Device Outflow Obstruction.

Left ventricular assist devices (LVADs) are used to support patients with advanced systolic heart failure (HF). These patients might develop LVAD dysfunction and consequent HF symptoms. Occasionally, outflow graft obstruction is responsible for LVAD dysfunction. Here, we describe percutaneous techniques to repair the outflow graft and avoid re-sternotomy.

Controlling axillary intra-aortic balloon pump inflation is a viable option for turning an acute heart failure patient into a chronic one.

Intra-aortic balloon pump (IABP) is often used to support patients in decompensated heart failure. Placement of the IABP via the axillary artery facilitates long-term support with the device and may allow for the conversion of an acute heart failure (HF) patient into a chronic HF patient using a modified weaning protocol; allowing for medical symptom management and removal of mechanical support. We will discuss strategies for supporting these complicated patients.

Frailty in the End-Stage Lung Disease or Heart Failure Patient: Implications for the Perioperative Transplant Clinician.

The syndrome of frailty for patients undergoing heart or lung transplantation has been a recent focus for perioperative clinicians because of its association with postoperative complications and poor outcomes. Patients with end-stage cardiac or pulmonary failure may be under consideration for heart or lung transplantation along with bridging therapies such as ventricular assist device implantation or venovenous extracorporeal membrane oxygenation, respectively. Early identification of frail patients in an attempt to modify the risk of postoperative morbidity and mortality has become an important area of study over the last decade. Many quantification tools and risk prediction models for frailty have been developed but have not been evaluated extensively or standardized in the cardiothoracic transplant candidate population. Heightened awareness of frailty, coupled with a better understanding of distinct cellular mechanisms and biomarkers apart from end-stage organ disease, may play an important role in potentially reversing frailty related to organ failure. Furthermore, the clinical management of these critically ill patients may be enhanced by waitlist and postoperative physical rehabilitation and nutritional optimization.

Perioperative Anesthetic and Transfusion Management of Veno-Venous Extracorporeal Membrane Oxygenation Patients Undergoing Noncardiac Surgery: A Case Series of 21 Procedures.

OBJECTIVES: To analyze the perioperative management of veno-venous extracorporeal membrane oxygenation (VV ECMO) in patients undergoing major noncardiac surgical procedures, which is poorly described in the literature. In doing so, perioperative challenges related to hemodynamic instability, impaired gas exchange, bleeding, and coagulopathy will be quantified. DESIGN: Retrospective, nonrandomized, observational study. SETTING: A single, university-affiliated, quaternary medical center. PARTICIPANTS: Fourteen patients who underwent 21 noncardiac surgical procedures during the period of January 1, 2014, through April 1, 2016. Approval for this study was obtained from the Duke University Medical Center Institutional Review Board (study Pro00072723). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Fifty percent of subjects were alive at 1 year after ECMO cannulation. Anesthetic type was variable with an inhaled anesthetic utilized in 71.4% of events, a presurgical continuous sedative was continued in 81.0% of cases, fentanyl was utilized in 100% of encounters, and midazolam was utilized in 71.4% of encounters. Intraoperatively, 50% of encounters resulted in an oxygen desaturation with a peripheral oxygen saturation assessed by pulse oximetry (SpO2)<90%, and 15% of procedures resulted in a SpO2 <80%. A vasopressor, most commonly epinephrine, was used during 66.7% of procedures. Intraoperatively, blood was administered in 52.4% of procedures, fresh frozen plasma was administered in 23.8% of procedures, and platelets were administered in 28.6% of procedures. Hemoglobin levels remained stable throughout the perioperative period, averaging 9.5 g/dL preoperatively, 9.7 g/dL immediately postoperatively, and 9.5 g/dL 24 hours after surgery. CONCLUSIONS: VV ECMO patients can be anesthetized using either inhalational or intravenous anesthetics. Patient hemodynamics, oxygenation, and decarboxylation require frequent interventions, but can typically be optimized to meet clinically acceptable thresholds.

Primary graft dysfunction after heart transplantation: Incidence, trends, and associated risk factors.

Changes in heart transplantation (HT) donor and recipient demographics may influence the incidence of primary graft dysfunction (PGD). We conducted a retrospective study to evaluate PGD incidence, trends, and associated risk factors by analyzing consecutive adult patients who underwent HT between January 2009 and December 2014 at our institution. Patients were categorized as having PGD using the International Society for Heart & Lung Transplantation (ISHLT)-defined criteria. Variables, including clinical and demographic characteristics of donors and recipients, were selected to assess their independent association with PGD. A time-trend analysis was performed over the study period. Three-hundred seventeen patients met inclusion criteria. Left ventricular PGD, right ventricular PGD, or both, were observed in 99 patients (31%). Risk factors independently associated with PGD included ischemic time, recipient African American race, and recipient amiodarone treatment. Over the study period, there was no change in the PGD incidence; however, there was an increase in the recipient pretransplantation use of amiodarone. The rate of 30-day mortality was significantly elevated in those with PGD versus those without PGD (6.06% vs 0.92%, P = .01). Despite recent advancements, incidence of PGD remains high. Understanding associated risk factors may allow for implementation of targeted therapeutic interventions.

Trends and outcomes of cardiac transplantation from donors dying of drug intoxication.

BACKGROUND: Deaths from drug intoxication have increased in the United States but outcomes of recipients of orthotopic heart transplantation (OHT) from these donors are not well characterized. METHODS: We performed a retrospective analysis of the United Network for Organ Sharing's STAR database between January 2000 and March 2014 and assessed mortality and retransplantation using adjusted Cox models by mechanism of donor death. RESULTS: Of the 31,660 OHTs from 2000 to 2014, 1233 (3.9%) were from drug intoxication. These donors were more likely to be female, white, with greater tobacco use and higher BMI compared to donors who died of other mechanisms. Drug intoxication accounted for 1.1% of OHT donors in 2000 and 6.2% in March 2014. No significant difference was observed in 10-year mortality (adjusted hazard ratio [HR], 95% confidence interval [CI]: 0.99, 0.87-1.13), 10-year retransplantation (adjusted HR 0.84, 0.49-1.41) or 1-year and 3-year rehospitalization with other mechanisms of death compared to drug intoxication. CONCLUSION: There has been a large increase in OHT donors who die of drug intoxication in the United States. OHT outcomes from these donors are similar to those dying from other mechanisms. These data have important implications for donor selection in context of the ongoing opioid epidemic.

Perioperative Management of the Adult Patient on Venovenous Extracorporeal Membrane Oxygenation Requiring Noncardiac Surgery.

The use of venovenous extracorporeal membrane oxygenation is increasing worldwide. These patients often require noncardiac surgery. In the perioperative period, preoperative assessment, patient transport, choice of anesthetic type, drug dosing, patient monitoring, and intraoperative and postoperative management of common patient problems will be impacted. Furthermore, common monitoring techniques will have unique limitations. Importantly, patients on venovenous extracorporeal membrane oxygenation remain subject to hypoxemia, hypercarbia, and acidemia in the perioperative setting despite extracorporeal support. Treatments of these conditions often require both manipulation of extracorporeal membrane oxygenation settings and physiologic interventions. Perioperative management of anticoagulation, as well as thresholds to transfuse blood products, remain highly controversial and must take into account the specific procedure, extracorporeal membrane oxygenation circuit function, and patient comorbidities. We will review the physiologic management of the patient requiring surgery while on venovenous extracorporeal membrane oxygenation.

Elevated Cardiac Troponin I in Preservation Solution Is Associated With Primary Graft Dysfunction.

BACKGROUND: Although primary graft dysfunction (PGD) is a leading cause of mortality and morbidity early post-heart transplant, relatively little is known regarding mechanisms involved in PGD development. METHODS AND RESULTS: We examined the relationship between cardiac troponin I (cTnI) concentrations in the preservation solution from 43 heart transplant procedures and the development of PGD. Donor hearts were flushed with cold preservation solution (University of Wisconsin [UW] or Custodiol) and stored in the same solution. cTnI concentrations were measured utilizing the i-STAT System and normalized to left ventricular mass. Recipient medical records were reviewed to determine PGD according to the 2014 ISHLT consensus conference. Nineteen patients developed PGD following cardiac transplantation. For both UW and Custodiol, normalized cTnI levels were significantly increased (P = .031 and .034, respectively) for those cases that developed PGD versus no PGD. cTnI levels correlated with duration of ischemic time in the UW group, but not for the Custodiol group. Donor age and donor cTnI (obtained prior to organ procurement) did not correlate with preservation cTnI levels in either UW or Custodiol. CONCLUSIONS: Increased preservation solution cTnI is associated with the development of PGD suggesting preservation injury may be a dominant mechanism for the development of PGD.

Surgical revascularization is associated with maximal survival in patients with ischemic mitral regurgitation: a 20-year experience.

BACKGROUND: The optimal treatment for ischemic mitral regurgitation remains actively debated. Our objective was to evaluate the relationship between ischemic mitral regurgitation treatment strategy and survival. METHODS AND RESULTS: We retrospectively reviewed patients at our institution diagnosed with significant coronary artery disease and moderate or severe ischemic mitral regurgitation from 1990 to 2009, categorized by medical treatment alone, percutaneous coronary intervention, coronary artery bypass grafting (CABG), or CABG plus mitral valve repair or replacement. Kaplan-Meier methods and multivariable Cox proportional hazards analyses were performed to assess the relationship between treatment strategy and survival, with the use of propensity scores to account for nonrandom treatment assignment. A total of 4989 patients were included: medical treatment alone=36%, percutaneous coronary intervention=26%, CABG=33%, and CABG plus mitral valve repair or replacement=5%. Median follow-up was 5.37 years. Compared with medical treatment alone, significantly lower mortality was observed in patients treated with percutaneous coronary intervention (adjusted hazard ratio, 0.83; 95% confidence interval, 0.76-0.92; P=0.0002), CABG (adjusted hazard ratio, 0.56; 95% confidence interval, 0.51-0.62; P<0.0001), and CABG plus mitral valve repair or replacement (adjusted hazard ratio, 0.69; 95% confidence interval, 0.57-0.82; P<0.0001). There was no significant difference in these results based on mitral regurgitation severity. CONCLUSIONS: Patients with significant coronary artery disease and moderate or severe ischemic mitral regurgitation undergoing CABG alone demonstrated the lowest risk of death. CABG with or without mitral valve surgery was associated with lower mortality than either percutaneous coronary intervention or medical treatment alone.

Patient Characteristics and Early Clinical Outcomes With Impella 5.5: A Systematic Review and Meta-Analysis.

Data regarding outcomes with Impella 5.5 are limited. The aim of this systematic review and meta-analysis was to summarize patient and treatment characteristics and early clinical outcomes among patients supported by Impella 5.5. A systematic literature search was conducted in PubMed, Scopus, and Cochrane databases from September 2019 to March 2023. Studies reporting outcomes in greater than or equal to 5 patients were included for review. Patient characteristics, treatment characteristics, and early clinical outcomes were extracted. Outcomes included adverse events, survival to hospital discharge, and 30 day survival. Random-effect models were used to estimate pooled effects for survival outcomes. Assessment for bias was performed using funnel plots and Egger's tests. Fifteen studies were included for qualitative review, representing 707 patients. Mean duration of support was 9.9 ± 8.2 days. On meta-analysis of 13 studies reporting survival outcomes, survival to hospital discharge was 68% (95% confidence interval [CI], 58-78%), and 30 day survival was 65% (95% CI, 56-74%) among patients with Impella devices predominantly supported by Impella 5.5 (>60%). There was significant study heterogeneity for these outcomes. Among 294 patients with Impella 5.5 only, survival to discharge was 78% (95% CI, 72-82%) with no significant study heterogeneity. This data present early benchmarks for outcomes with Impella 5.5 as clinical experience with these devices accrues.

Ex vivo lung perfusion in donation after circulatory death: A post hoc analysis of the Normothermic Ex Vivo Lung Perfusion as an Assessment of Extended/Marginal Donors Lungs trial.

OBJECTIVE: Donation after circulatory death (DCD) donors offer the ability to expand the lung donor pool and ex vivo lung perfusion (EVLP) further contributes to this ability by allowing for additional evaluation and resuscitation of these extended criteria donors. We sought to determine the outcomes of recipients receiving organs from DCD EVLP donors in a multicenter setting. METHODS: This was an unplanned post hoc analysis of a multicenter, prospective, nonrandomized trial that took place during 2011 to 2017 with 3 years of follow-up. Patients were placed into 3 groups based off procurement strategy: brain-dead donor (control), brain-dead donor evaluated by EVLP, and DCD donors evaluated by EVLP. The primary outcomes were severe primary graft dysfunction at 72 hours and survival. Secondary outcomes included select perioperative outcomes, and 1-year and 3-years allograft function and quality of life measures. RESULTS: The DCD EVLP group had significantly higher incidence of severe primary graft dysfunction at 72 hours (P = .03), longer days on mechanical ventilation (P < .001) and in-hospital length of stay (P = .045). Survival at 3 years was 76.5% (95% CI, 69.2%-84.7%) for the control group, 68.3% (95% CI, 58.9%-79.1%) for the brain-dead donor group, and 60.7% (95% CI, 45.1%-81.8%) for the DCD group (P = .36). At 3-year follow-up, presence observed bronchiolitis obliterans syndrome or quality of life metrics did not differ among the groups. CONCLUSIONS: Although DCD EVLP allografts might not be appropriate to transplant in every candidate recipient, the expansion of their use might afford recipients stagnant on the waitlist a viable therapy.

Risk-adjusted survival after tissue versus mechanical aortic valve replacement: a 23-year assessment.

BACKGROUND AND AIM OF THE STUDY: Detailed analyses of risk-adjusted outcomes after mitral valve surgery have documented significant survival decrements with tissue valves at any age. Several recent studies of prosthetic aortic valve replacement (AVR) also have suggested a poorer performance of tissue valves, although analyses have been limited to small matched series. The study aim was to test the hypothesis that AVR with tissue valves is associated with a lower risk-adjusted survival, as compared to mechanical valves. METHODS: Between 1986 and 2009, primary isolated AVR, with or without coronary artery bypass grafting (CABG), was performed with currently available valve types in 2148 patients (1108 tissue valves, 1040 mechanical). Patients were selected for tissue valves to be used primarily in the elderly. Baseline and operative characteristics were documented prospectively with a consistent variable set over the entire 23-year period. Follow up was obtained with mailed questionnaires, supplemented by National Death Index searches. The average time to death or follow up was seven years, and follow up for survival was 96.2% complete. Risk-adjusted survival characteristics for the two groups were evaluated using a Cox proportional hazards model with stepwise selection of candidate variables. RESULTS: Differences in baseline characteristics between groups were (tissue versus mechanical): median age 73 versus 61 years; non-elective surgery 32% versus 28%; CABG 45% versus 35%; median ejection fraction 55% versus 55%; renal failure 6% versus 1%; diabetes 18% versus 7% (p<0.01). Unadjusted Kaplan-Meier survival was significantly lower with tissue than mechanical valves; however, after risk adjustment for the adverse profiles of tissue valve patients, no significant difference was observed in survival after tissue or mechanical AVR. Thus, the hypothesis did not hold, and risk-adjusted survival was equivalent, of course qualified by the fact that selection bias was evident. CONCLUSION: With selection criteria that employed tissue AVR more frequently in elderly patients, tissue and mechanical valves achieved similar survival characteristics across the spectrum of patient risk. Further studies of the relative outcomes of mechanical versus tissue valves across the spectrum of patient age seem indicated.

The Society of Thoracic Surgeons Adult Cardiac Surgery Database: 2022 Update on Outcomes and Research.

The Society of Thoracic Surgeons Adult Cardiac Surgery Database is the most mature and comprehensive cardiac surgery database. It is one of the most respected clinical data registries in health care, providing accurate risk-adjusted benchmarks, a foundation for quality measurement and improvement activities, and the ability to perform novel research. This report encompasses data from the years 2020 and 2021 and is the seventh in a series of reports that provide updated volumes, outcomes, database-related developments, and research summaries using the Adult Cardiac Surgery Database.