Feasibility Testing of the Bionet Sonar Ultrasound Transcutaneous Energy Transmission (UTET) System for Wireless Power and Communication of a LVAD.

PURPOSE: To address the clinical need for totally implantable mechanical circulatory support devices, Bionet Sonar is developing a novel Ultrasonic Transcutaneous Energy Transmission (UTET) system that is designed to eliminate external power and/or data communication drivelines. METHODS: UTET systems were designed, fabricated, and pre-clinically tested using a non-clinical HeartWare HVAD in static and dynamic mock flow loop and acute animal models over a range of pump speeds (1800, 2400, 3000 RPM) and tissue analogue thicknesses (5, 10, 15 mm). RESULTS: The prototypes demonstrated feasibility as evidenced by meeting/exceeding function, operation, and performance metrics with no system failures, including achieving receiver (harvested) power exceeding HVAD power requirements and data communication rates of 10kB/s and pump speed control (> 95% sensitivity and specificity) for all experimental test conditions, and within healthy tissue temperature range with no acute tissue damage. CONCLUSION: During early-stage development and testing, engineering challenges for UTET size reduction and stable and safe operation were identified, with solutions and plans to address the limitations in future design iterations also presented.

Ex vivo heart perfusion: an updated systematic review.

Due to the discrepancy between patients awaiting a heart transplant and the availability of donor hearts, strategies to expand the donor pool and improve the transplant's success are crucial. This review aims to summarize current knowledge on the ex vivo heart preservation (EVHP) experience as an alternative to standard cold static storage (CSS). EVHP techniques can improve the preservation of the donor's heart before transplantation and allow for pre-transplant organ evaluation.

Early-stage Development of the CoRISMA Mechanical Circulatory Support (CMCS) System for Heart Failure Therapy.

PURPOSE: CoRISMA MCS Systems Inc (Hamden CT) is developing an innovative mechanical circulatory support system (CMCS) as a durable therapeutic option for heart failure (HF) patients. The CMCS system is comprised of an axial flow pump, non-contacting hydrodynamic bearings, and integrated DC motor designed to be fully implantable in a left atrial (LA) to aortic (Ao) configuration; this unloading strategy may be particularly beneficial for HF patients with preserved ejection fraction (HFpEF). The small (5.5 cm3), lightweight (20 g), and low power (5-7 W) device design should allow for a less invasive off-pump implant. We present early-stage engineering development and testing of the prototype CoRISMA pumps. METHODS: Computational fluid dynamics (CFD) modeling was performed to evaluate flow and shear in two impeller (3 blades, 0.5 mm thickness, 8.9 mm diameter, 0.15 mm gap, polished titanium) and diffusor (5 blades, polished titanium) candidate designs. Test apparatuses were custom built to expedite development of the impeller/diffuser designs and iteratively refine the CFD models. Two candidate impeller/diffusor designs were fabricated and tested in each of the two test apparatuses (n = 4 impeller/diffuser + test fixture configurations) in static mock flow loops (hydrodynamic H-Q curves, 3.5 cP glycerol solution at 37 °C), and in dynamic mock flow loops (hemodynamics, 3.5 cP glycerol solution at 37 °C) tuned to HF conditions (mean aortic pressure 50 mmHg, central venous pressure 15 mmHg, aortic flow 3.0 L/min, and heart rate 80 bpm). RESULTS: CFD predicted flows of 4.56 L/min and 4.82 L/min at 100 mmHg for impellers/diffusers 1 and 2, respectively. Impeller 2 required less torque to generate a 6% increase in fluidic flow, and the diffuser had a larger area of high pressure, indicative of lower friction, which likely contributed to the increased efficiency. Experimental testing for all four configurations in the static and dynamic mock loops met performance metrics as evidenced by generating 4.0-4.5 L/min flow against 70-76 mmHg pressure at 25,000 rpm and restoring hemodynamics in the dynamic mock flow loop (MAP = 80 mmHg, CVP = 0 mmHg, total flow = 5.5 L/min) from baseline simulated HF test conditions. CONCLUSION: These results demonstrate proof-of-concept of the early engineering design and performance of the prototype CoRISMA pumps. Engineering specifications, challenges observed, and proposed solutions for the next design iteration were identified for the continued development of an effective, reliable, and safe LA-to-Ao CMCS system for HF patients. Current design plans are underway for incorporating a wireless energy transfer system for communication and power, eliminating the need for and complications associated with an external driveline, to achieve a fully-implantable system.

Deactivation of LVAD support for myocardial recovery-surgical perspectives.

Left ventricular assist devices (LVADs) are excellent therapies for advanced heart failure patients either bridged to transplant or for lifetime use. LVADs also allow for reverse remodeling of the failing heart that is often associated with functional improvement. Indeed, growing enthusiasm exists to better understand this population of patients, whereby the LVAD is used as an adjunct to mediate myocardial recovery. When patients achieve benchmarks suggesting that they no longer need LVAD support, questions related to the discontinuation of LVAD therapy become front and center. The purpose of this review is to provide a surgical perspective on the practical and technical issues surrounding LVAD deactivation.

Integrating molecular and clinical variables to predict myocardial recovery.

Mechanical unloading and circulatory support with left ventricular assist devices (LVADs) mediate significant myocardial improvement in a subset of advanced heart failure (HF) patients. The clinical and biological phenomena associated with cardiac recovery are under intensive investigation. Left ventricular (LV) apical tissue, alongside clinical data, were collected from HF patients at the time of LVAD implantation (n=208). RNA was isolated and mRNA transcripts were identified through RNA sequencing and confirmed with RT-qPCR. To our knowledge this is the first study to combine transcriptomic and clinical data to derive predictors of myocardial recovery. We used a bioinformatic approach to integrate 59 clinical variables and 22,373 mRNA transcripts at the time of LVAD implantation for the prediction of post-LVAD myocardial recovery defined as LV ejection fraction (LVEF) ≥40% and LV end-diastolic diameter (LVEDD) ≤5.9cm, as well as functional and structural LV improvement independently by using LVEF and LVEDD as continuous variables, respectively. To substantiate the predicted variables, we used a multi-model approach with logistic and linear regressions. Combining RNA and clinical data resulted in a gradient boosted model with 80 features achieving an AUC of 0.731±0.15 for predicting myocardial recovery. Variables associated with myocardial recovery from a clinical standpoint included HF duration, pre-LVAD LVEF, LVEDD, and HF pharmacologic therapy, and LRRN4CL (ligand binding and programmed cell death) from a biological standpoint. Our findings could have diagnostic, prognostic, and therapeutic implications for advanced HF patients, and inform the care of the broader HF population.

Anatomical and Hemodynamic Characterization of Totally Artificial Hearts.

We characterize the anatomy and function of never before studied total artificial hearts (TAHs) using established methods for testing mechanical circulatory support (MCS) devices. A historical review of TAHs is also presented to aid in benchmarking performance metrics. Six TAHs, ranging from spooky Halloween beating hearts to a cute colorful plush heart, were imaged, instrumented (mock flow loops) to measure their pressure, volume, and flow, and qualitatively evaluated by 3rd party cardiac surgeons for anatomical accuracy and surgical considerations. Imaging of Claw, Beating, and Frankenstein TAHs revealed internal motors, circuit boards, and speakers. Gummy TAH was ranked favorite TAH for tactile realism, while Frankenstein TAH had the most favorable audible/visual indicators, including an illuminated Jacob's Ladder. Beating TAH demonstrated superior pulsatile hemodynamic performance compared to Claw TAH (16mL vs 1.3mL stroke volume). Light Up TAH and Gummy TAH functioned only as passive compliance chambers. Cute TAH rapidly exsanguinated due to its porosity (-3.0 L/min flow). These TAHs demonstrated a wide range of anatomical accuracy, surgeon appeal, unique features, and hemodynamic performance. While Claw TAH and Beating TAH successfully generated a modicum of pulsatility, we recommend the clinical community continue to support pre-clinical development of emerging or use of clinically-approved TAHs.

Management of contained penetrating cardiac injury in a patient with prior cardiac surgery.

Penetrating cardiac injuries usually require emergent surgical intervention. Our patient presented to the trauma centre with multiple stab wounds to the neck, chest, epigastric region and abdomen. She arrived haemodynamically stable, and her initial Focused Assessment with Sonography for Trauma exam was negative. Her chest X-ray did not show any evident pneumothorax or haemothorax. Due to her injury pattern, she was taken to the operating room for exploratory laparotomy and neck exploration. Postoperatively, she was taken for CT and found to have a contained cardiac rupture. The injury was contained within previous scar tissue from her prior cardiac surgery. Further evaluation revealed that the injury included a penetrating stab wound to the right ventricle and a traumatic ventricular septal defect (VSD). She subsequently underwent a redo sternotomy with the repair of the penetrating stab wound and the VSD. Cardiology, intensive care, trauma surgery and cardiothoracic surgery coordinated her care from diagnosis, management and recovery. This case highlights the challenges in the management of cardiac injuries and the benefits of a multidisciplinary approach to care for complex cardiac injuries.

Trends and outcomes of heart transplantation in adults with congenital heart disease.

OBJECTIVES: Heart transplantation for adult congenital heart disease is complicated and associated with challenging pretransplant support, long waiting and high early post-transplant mortality. We explored if surgical and medical advances and allocation system changes have affected outcomes. METHODS: From United Network for Organ Sharing database, adults with congenital heart disease listed for heart transplantation were queried. To explore practice and outcome trends, patients were divided into 4 eras (eras 1-3: nearly 3 equal periods from 1992 to 2018, era 4: after 2018, corresponding with new allocation system). Univariate and multivariable analysis was performed to evaluate outcomes. RESULTS: A total of 2737 patients were listed. There was gradual increase in listed and transplanted patients, along with significant increase in use of mechanical support, simultaneous kidney and liver transplantation. While proportion of transplanted remained constant, there was decrease in proportion delisted/died after listing (P = 0.01) and waiting list duration (P = 0.01), especially in era 4. Thirty-day post-transplant mortality remains high; however, it has significantly improved starting era 3 (P = 0.01). Current survival at 1-year and 5-years is 85% and 65%, with improvement mainly related to decreased early death. On multivariable analysis, factors associated with survival were lower glomerular filtration rate (hazard ratio = 0.99, P = 0.042), bilirubin (hazard ratio = 1.17, P<0.001) and mechanical ventilation (hazard ratio = 2.3, P=0.004). CONCLUSIONS: Heart transplantation in adults with congenital heart disease is increasing, along with added complexity, higher usage of pretransplant mechanical support and simultaneous organ transplantation. Despite that, more complex patients do not experience worse outcomes. Early mortality improved but remains high. New donor allocation system allowed shorter waiting time and higher proportion transplanted without altering early mortality.

Left ventricular assist devices: yesterday, today, and tomorrow.

The shortcomings of expense, power requirements, infection, durability, size, and blood trauma of current durable LVADs have been recognized for many years. The LVADs of tomorrow aspire to be fully implantable, durable, mitigate infectious risk, mimic the pulsatile nature of the native cardiac cycle, as well as minimize bleeding and thrombosis. Power draw, battery cycle lifespan and trans-cutaneous energy transmission remain barriers to completely implantable systems. Potential solutions include decreases in pump electrical draw, improving battery lifecycle technology and better trans-cutaneous energy transmission, potentially from Free-range Resonant Electrical Energy Delivery. In this review, we briefly discuss the history of LVADs and summarize the LVAD devices in the development pipeline seeking to address these issues.

Ambulatory Extracorporeal Membrane Oxygenation Use in Patients Listed for Lung Transplant.

There has been an increase in the use of extracorporeal membrane oxygenation (ECMO) to bridge critically ill patients to lung transplant (LTX). This study evaluates how ambulatory status on ECMO affected waitlist and post-LTX outcomes. The United Network of Organ Sharing (UNOS) database was queried for patients aged of greater than or equal to 18 years and between 2016 and 2021 to identify pre-LTX patients supported by ECMO. The patients were classified in venous-arterial (VA) ECMO and veno-venous (VV) ECMO cohorts and further classified as ambulatory (AMB) and non-AMB (nAMB). Each cohort was controlled against the non-ECMO patients. Univariate statistical tests, as well as Kaplan-Meier survival curves, were used for analysis. The 90 day waitlist survival was the highest among the non-ECMO group (96%), but both AMB VV and VA groups had superior survival compared to the nAMB group (85% vs. 75%, 78% vs. 65%, p < 0.01). After adjusting for the median lung allocation score (LAS) (88) in the VV ECMO group, the waitlist survival was superior in the AMB VV ECMO compared to those not on ECMO (86% vs. 78%, p > 0.01). The 1 year post-LTX survival between non-ECMO and AMB VV ECMO was comparable (88% vs. 88%, p = 0.66). Ambulating patients or use of physical therapy while on ECMO can help improve lung transplant outcomes.

Cannula Placement for Cerebral Protection Without Circulatory Arrest in Patients Undergoing Hemiarch Aortic Aneurysm Repair.

BACKGROUND: Aortic aneurysms involving the proximal aortic arch, which require hemiarch-type repair, typically require circulatory arrest with antegrade cerebral perfusion. Left carotid antegrade cerebral perfusion (LCP) via distal arch cannulation without circulatory arrest was used in this study's patient population. The goal was to assess the operative efficiency and clinical outcomes of using a distal arch cannulation technique that would not require any hypothermic circulatory arrest (HCA) time compared with more traditional brachiocephalic artery cannulation with right-sided unilateral antegrade cerebral perfusion (RCP) and HCA. METHODS: A single-center retrospective review of patients with replacement of the distal ascending aorta involving the proximal arch was performed. Patients with an intramural hematoma or dissection were excluded. Between January 2015 and December 2019, 68 adult patients had undergone a hemiarch repair because of aneurysmal disease. Analysis of baseline demographics, operative data, and clinical outcomes was performed. RESULTS: Comparing the 68 patients: 21 patients were treated with RCP (via brachiocephalic artery graft with HCA), and 47 patients were treated with LCP (via distal aortic arch cannulation with cross-clamp between the brachiocephalic and left common carotid arteries without HCA). Baseline characteristics and outcomes were evaluated for both groups. The LCP group was younger (LCP median [IQR] age, 60 [53-65] years vs RCP median [IQR] age, 67 [59-71] years]. Sex, race, body mass index, comorbidities, and ejection fraction were similar between the groups. Cardiopulmonary bypass time (LCP, 123 minutes vs RCP, 149 minutes) and unilateral cerebral perfusion time (LCP, 17 minutes vs RCP, 22 minutes) were longer in the RCP group. Bleeding, prolonged ventilatory support, kidney failure, and length of stay were similar. In-hospital mortality was 2% in the LCP group vs 0% in the RCP group. Stroke occurred in 2 patients (4.2%) in the LCP group and in 0% of the RCP group. Mortality at 6 months in the LCP and RCP groups was 3% and 10%, respectively. CONCLUSION: Distal arch cannulation with LCP without HCA is a reasonable and safe alternative strategy for patients requiring hemiarch replacement for aneurysmal disease. This technique may provide additional benefits by avoiding circulatory arrest in these complex cases.

Techniques and Technologies to Improve Vein Graft Patency in Coronary Surgery.

Vein grafts are the most used conduits in coronary artery bypass grafting (CABG), even though many studies have suggested their lower patency compared to arterial alternatives. We have reviewed the techniques and technologies that have been investigated over the years with the aim of improving the quality of these conduits. We found that preoperative and postoperative optimal medical therapy and no-touch harvesting techniques have the strongest evidence for optimizing vein graft patency. On the other hand, the use of venous external support, endoscopic harvesting, vein preservation solution and anastomosis, and graft configuration need further investigation. We have also analyzed strategies to treat vein graft failure: when feasible, re-doing the CABG and native vessel primary coronary intervention (PCI) are the best options, followed by percutaneous procedures targeting the failed grafts.

Left Atrial-Veno Arterial Extracorporeal Membrane Oxygenation as a Bridge to Surgery for Endocarditis-Related Acute Severe Aortic Regurgitation.

Mechanical circulatory support for cardiogenic shock complicated by acute severe aortic regurgitation poses a unique challenge for traditional veno arterial extracorporeal membrane oxygenation (ECMO) because of rapidly rising left ventricular pressures accentuated by the increased afterload from retrograde flow in femoral cannulation. This process necessitates rapid left ventricular unloading while also allowing for adequate native left ventricular function. Herein, we describe a case of cardiogenic and septic shock secondary to methicillin-resistant Staphylococcus aureus complicated by acute severe aortic regurgitation temporized by left atrial-veno arterial (LA-VA) ECMO via the Livanova TandemHeart system. Left ventricular unloading created a window of hemodynamic stability allowing for optimization of multiorgan failure and infectious source control before surgical aortic valve replacement.

Predictors of Survival After Heart Transplant in the New Allocation System: A UNOS Database Analysis.

Clinical predictors of posttransplant graft loss since the United Network for Organ Sharing (UNOS) heart allocation system change have not been well characterized. Single organ adult heart transplants from the UNOS database were identified (n = 10,252) and divided into a test cohort (n = 6,869, 67%) and validation cohort (n = 3,383, 33%). A Cox regression analysis was performed on the test cohort to identify recipient and donor risk factors for posttransplant graft loss. Based on the risk factors, a score (max 16) was developed to classify patients in the validation cohort into risk groups of low (≤1), mid (2-3), high (≥4) risk. Recipient factors of advanced age, Black race, recipient blood group O, diabetes, etiology of heart failure, renal dysfunction, elevated bilirubin, redo-transplantation, elevated pulmonary artery pressure, transplant with a durable ventricular assist device, or transplant on extracorporeal membrane oxygenation (ECMO) or ventilator were associated with more posttransplant graft loss. Donor factors of ischemic time and donor age were also associated with outcomes. One year graft survival for the low-, mid-, high-risk groups was 94%, 91%, and 85%, respectively. In conclusion, easily obtainable clinical characteristics at time of heart transplant can predict posttransplant outcomes in the current era.

Optimizing Safety and Success: The Advantages of Bloodless Cardiac Surgery. A Systematic Review and Meta-Analysis of Outcomes in Jehovah's Witnesses.

Transfusions are extremely frequent after cardiac surgery, and they have a considerable economic burden and impact on outcomes. Optimal patient blood management could play a fundamental role in reducing the rate of transfusion and Jehovah's Witnesses (JW) represent the ideal surrogate study population. This meta-analysis compares outcomes of JWs and non-JWs' patients undergoing cardiac surgery, assessing the safety of a bloodless cardiac surgery. A scoping review was conducted using a search strategy for studies assessing outcomes of JW undergoing cardiac surgery. The primary outcome was perioperative mortality, and a random-effects meta-analysis was performed. Ten studies were included in our meta-analysis, involving 780 JW patients refusing any type of transfusion ("JW") and 1182 patients accepting transfusion if needed ("non-JW"). 86% of non-JW patients received at least 1 transfusion. There was no significant difference in terms of perioperative mortality (OR 0.91; 95% CI 0.55-1.52; p = 0.72). The volume blood loss was significantly less in the JW (p = 0.001), while the rate of reoperation for bleeding was also lower, but not statistically significative, in the JW (p = 0.16). Both preoperative and postoperative hemoglobin and hematocrit were significantly higher in the JW. Therefore, we concluded that bloodless cardiac surgery is safe and early outcomes are similar between JW and non-JW patients: optimal patient blood management is fundamental in guarantying these results. Further studies are needed to assess if a limitation of transfusion could have a positive long-term impact on outcomes.

Surgical Ablation for Atrial Fibrillation During Mitral Valve Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Although surgical ablation has been shown to produce excellent outcomes at follow-up for patients with atrial fibrillation who underwent mitral valve replacement/repair (MVR), this procedure is not commonly performed. Our objective was to conduct a systematic review and meta-analysis to evaluate the outcomes of concomitant surgical ablation during MVR. Three databases were systematically reviewed for randomized clinical trials published by August 2022. The primary outcome was sinus rhythm (SR) at 12 months. Secondary outcomes included SR at discharge and 6 months, all-cause mortality, permanent pacemaker implantation, and stroke and thromboembolic events. A random-effects meta-analysis was performed, calculating odds ratios (ORs) for each outcome. Thirteen studies were included, involving 1,089 patients comparing patients who underwent either isolated MVR ("MVR-only") or concomitant surgical ablation during MVR ("MVR+Ablation"). The odds of SR were significantly higher in the MVR+Ablation group at discharge (OR 9.62, 95% confidence interval [CI] 4.87 to 19.02, I2 = 55%), at 6-month follow-up (OR 7.21, 95% CI 4.30 to 12.11, I2 = 34%), and at 1-year follow-up (OR 8.41, 95% CI 5.14 to 13.77, I2 = 48%). All-cause mortality was not different in the groups, as were stroke and thromboembolic events, whereas the odds of permanent pacemaker implantation were slightly higher in the MVR+Ablation group (OR 1.87, 95% CI 1.11 to 3.17, I2 = 0%). Concomitant surgical ablation during MVR showed excellent outcomes at short-term follow-up, despite a slightly higher rate of permanent pacemaker implantation. Further studies with longer follow-ups are needed to assess if the SR is maintained over the years.

Durable left ventricular assist device implant-how I teach it.

Left ventricular assist devices (LVADs) have become a mainstay of advanced heart failure therapy. The technical aspects of performing a device implant are nuanced and attention to these details allows for successful therapy with good outcomes. As more patient with heart failure are expected to benefit from mechanical circulatory support, the need for a concise and consistent technique for LVAD implantation is needed. Teaching this procedure is most comprehensible when broken down into separate steps, as with many other procedures. Here, we describe our standard protocol for LVAD implantation, as well as rudimentary outcomes of 6-year experience in our center. We hope this will provide some insight and guidance to centers who are expanding into the field of mechanical circulatory support and can help them form a foundation with which to build their own experience and success.