Heart Transplant and Donors After Circulatory Death: A Clinical-Preclinical Systematic Review.

INTRODUCTION: Heart transplantation is the treatment of choice for end-stage heart failure. There is a mismatch between the number of donor hearts available and the number of patients awaiting transplantation. Expanding the donor pool is critically important. The use of hearts donated following circulatory death is one approach to increasing the number of available donor hearts. MATERIALS AND METHODS: A systematic review was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines utilizing Pubmed/MEDLINE and Embase. Articles including adult human studies and preclinical animal studies of heart transplantation following donation after circulatory death were included. Studies of pediatric populations or including organs other than heart were excluded. RESULTS: Clinical experience and preclinical studies are reviewed. Clinical experience with direct procurement, normothermic regional perfusion, and machine perfusion are included. Preclinical studies addressing organ function assessment and enhancement of performance of marginal organs through preischemic, procurement, preservation, and reperfusion maneuvers are included. Articles addressing the ethical considerations of thoracic transplantation following circulatory death are also reviewed. CONCLUSIONS: Heart transplantation utilizing organs procured following circulatory death is a promising method to increase the donor pool and offer life-saving transplantation to patients on the waitlist living with end-stage heart failure. There is robust ongoing preclinical and clinical research to optimize this technique and improve organ yield. There are also ongoing ethical considerations that must be addressed by consensus before wide adoption of this approach.

Concomitant abdominal exploration with durable left ventricular assist device implantation.

A 45-year-old male presented in decompensated heart failure from nonischemic cardiomyopathy and was implanted with a right transaxillary intra-aortic balloon pump. He was listed for heart transplantation but after 9 days, he developed abdominal pain with evidence of embolization on computed tomography scan despite a well-positioned balloon pump. He underwent concomitant abdominal exploration with small bowel resection and durable left ventricular assist device implantation. He recovered well and was discharged home. This case highlights the challenges of decision-making in the current era where intra-aortic balloon pumps are being utilized more frequently as a bridge to heart transplantation.

Minimally Invasive Direct Aortic Implantation of Impella 5.5 As Bridge to Transplant: A Case Report.

The use of temporary mechanical circulatory support in cardiogenic shock (CS) is increasing. The Impella (Abiomed) is a percutaneous, microaxial ventricular assist device approved for short-term use in CS that can be implanted peripherally. Direct aortic placement is an alternative commonly performed when the sternum is open, for example, in post-cardiotomy shock or when the peripheral vasculature is of insufficient size or quality for implantation. Herein, we describe direct aortic implantation of the Impella 5.5 via right mini-thoracotomy for a patient in CS secondary to decompensated heart failure as a bridge to candidacy and, ultimately, transplantation.

Hospital Readmissions in Patients Supported with Durable Centrifugal-Flow Left Ventricular Assist Devices.

Background: Centrifugal-flow left ventricular assist devices (CF-LVADs) have improved morbidity and mortality for their recipients. Hospital readmissions remain common, negatively impacting quality of life and survival. We sought to identify risk factors associated with hospital readmissions among patients with CF-LVADs. Methods: Consecutive patients receiving a CF-LVAD between February 2011 and March 2021 were retrospectively evaluated using prospectively maintained institutional databases. Hospital readmissions within three years post-LVAD implantation were dichotomized into heart failure (HF)/LVAD-related or non-HF/LVAD-related readmissions. Multivariable Cox regression models augmented using a machine learning algorithm, the least absolute shrinkage and selection operator (LASSO) method, for variable selection were used to estimate associations between HF/LVAD-related readmissions and pre-, intra- and post-operative clinical variables. Results: A total of 204 CF-LVAD recipients were included, of which 138 (67.7%) had at least one HF/LVAD-related readmission. HF/LVAD-related readmissions accounted for 74.4% (436/586) of total readmissions. The main reasons for HF/LVAD-related readmissions were major bleeding, major infection, HF exacerbation, and neurological dysfunction. Using pre-LVAD variables, HF/LVAD-related readmissions were associated with substance use, previous cardiac surgery, HF duration, pre-LVAD inotrope dependence, percutaneous LVAD/VA-ECMO support, LVAD type, and the left ventricular ejection fraction in multivariable analysis (Harrell's concordance c-statistic; 0.629). After adding intra- and post-operative variables in the multivariable model, LVAD implant hospitalization length of stay was an additional predictor of readmission. Conclusions: Using machine learning-based techniques, we generated models identifying pre-, intra-, and post-operative variables associated with a higher likelihood of rehospitalizations among patients on CF-LVAD support. These models could provide guidance in identifying patients with increased readmission risk for whom clinical strategies to mitigate this risk may further improve LVAD recipient outcomes.

Case Report of Needle Disruption of the Retroperitoneal Lymph Nodes for Refractory Chylothorax After Double Lung Transplantation.

Chylothorax is a rare complication after double lung transplantation. We report a case of a 55-year-old man with idiopathic pulmonary fibrosis. He underwent a double lung transplantation with venoarterial extracorporeal membrane support. The surgery was uncomplicated; however, his postoperative course was complicated with a refractory chylothorax that started postoperative day 4. Medical management could not control the chylothorax, including nil per os, total parenteral nutrition, and octreotide administration. After failed percutaneous embolization via lymphangiography and surgical ligation of the thoracic duct and pleurodesis via video-assisted thoracoscopic surgery, percutaneous needle disruption of the retroperitoneal lymph nodes was performed. After this procedure, the chylothorax resolved quickly. Percutaneous needle disruption of the retroperitoneal lymph node is safe and effective for refractory chylothorax. This technique can be one of the main modalities to manage chylothorax after lung transplantation.

A Case Report of Triple Organ Transplantation From a Donor After Circulatory Death Using Thoraco-Abdominal Normothermic Regional Perfusion.

Organ transplantation with donation after circulatory death can potentially increase the donor pool. Here, we report the rare case of triple-organ (heart/liver/kidney) transplantation from a donor after circulatory death using thoraco-abdominal normothermic regional perfusion. The recipient was a 61-year-old man with end-stage heart failure, liver failure, and kidney failure secondary to arrhythmogenic right ventricular dysplasia. He received a heart/liver/kidney transplantation from a donor after circulatory death. The course was complicated with primary graft dysfunction of the heart that resolved on postoperative day 3. The patient was discharged on postoperative day 39. He has no evidence for rejection on heart biopsy, and all 3 organs exhibit stable function. The use of donation after cardiac death donors greatly increases the donor pool and should be considered for patients requiring multiorgan transplantation. The use of thoraco-abdominal normothermic reperfusion is not only a feasible method for multiorgan procurement but also provides enhanced protection for all transplanted organs.

[Severe intestinal ischemia due to chronic aortic dissection; report of a case].

We report a rare case with severe intestinal ischemia due to chronic aortic dissection. A 75-year-old man was admitted to our hospital with abdominal and right leg pain. The patient had a history of aortic dissection (Stanford type B) 12 years before admission and had been treated medically. Although a throaco-abdominal aneurysm due to aortic dissection (Crowford type III) had been diagnosed 1 year before admission, he had rejected the operation. Computed tomography (CT) revealed an increased diameter of the aneurysm (6 cm). As abdominal pain was increased, emergent surgery was performed on day 1 after admission. Although perfusion of the superior mesenteric artery and marginal artery was maintained, intestinal ischemia was worsening and general condition was deteriorated during surgery. Bypass surgery and/or resection of colon were not indicated because of peripheral colon artery ischemia, and he expired day 1 after surgery.

Minimally Invasive versus Full Sternotomy SAVR in the Era of TAVR: An Institutional Review.

In the era of advancing transcatheter aortic valve replacement (TAVR) technology, traditional open surgery remains a valuable intervention for patients who are not TAVR candidates. We sought to compare perioperative variables and postoperative outcomes of minimally invasive and full sternotomy surgical aortic valve replacement (SAVR) at a single institution. A retrospective analysis of 113 patients who underwent isolated SAVR via full sternotomy or upper hemi-sternotomy between January 2015 and December 2019 at the University of Utah Hospital was performed. Preoperative comorbidities and demographic information were not different among groups, with the exception of diabetes, which was significantly more common in the full sternotomy group (p = 0.01). Median procedure length was numerically shorter in the minimally invasive group but was not significant following the Bonferroni correction (p = 0.047). Other perioperative variables were not significantly different. The two groups showed no difference in the incidence of postoperative adverse events (p = 0.879). As such, minimally invasive SAVR via hemi-sternotomy remains a safe and effective alternative to full sternotomy for patients who meet the criteria for aortic valve replacement.

Effect of Portable, In-Hospital Extracorporeal Membrane Oxygenation on Clinical Outcomes.

The time between onset of cardiogenic shock and initiation of mechanical circulatory support is inversely related to patient survival as delays in transporting patients to the operating room (OR) for venoarterial extracorporeal membrane oxygenation (VA ECMO) could prove fatal. A primed and portable VA ECMO system may allow faster initiation of ECMO in various hospital locations and subsequently improve outcomes for patients in cardiogenic shock. We reviewed our institutional experience with VA ECMO based on two time periods: beginning of our VA ECMO program and from initiation of our primed and portable in-hospital ECMO system. The primary endpoint was patient survival to discharge. A total of 137 patients were placed on VA ECMO during the study period; n = 66 (48%) before and n = 71 (52%) after program initiation. In the second era, the proportion of OR ECMO initiation decreased significantly (from 92% to 49%, p < 0.01) as more patients received ECMO in other hospital units, including the emergency department (p < 0.01) and during cardiac arrest (12% vs. 38%, p < 0.01). Survival to hospital discharge was equivalent between the two groups (30% vs. 42%, p = 0.1) despite more patients being placed on ECMO during ongoing cardiac arrest. Finally, we observed increased clinical volume since initiation of the in-hospital, portable ECMO system. Developing an in-hospital, primed and portable VA ECMO program resulted in increased clinical volume with equivalent patient survival despite a sicker cohort of patients. We conclude that more rapid deployment of VA ECMO may extend the treatment eligibility to more patients and improve patient outcomes.

Left ventricular assist device implant and subsequent orthotopic heart transplant after chronic type B aortic dissection.

The criteria for being placed on the list of the International Society for Heart and Lung Transplantation for an orthotopic heart transplant mention nothing about patients with aortic dissection. Nor are there any guidelines pertaining to the patient with type B aortic dissection. Herein, we report the case of a patient with chronic type B aortic dissection for whom we successfully performed a left ventricular assist device implant followed by an orthotopic heart transplant.

Aortic Insufficiency After Left Ventricular Assist Device Implantation: Predictors and Outcomes.

BACKGROUND: The aim of this study was to evaluate the incidence, risk factors, and clinical impact of progression of aortic insufficiency (AI) after left ventricular assist device (LVAD) implantation. METHODS: Patients undergoing primary durable LVAD implantation between 2004 and 2018 were included. Significant AI was defined as more than mild AI. Clinical and echocardiographic data were collected. Patients were stratified by degree of pre-LVAD AI into 3 groups: no AI, group I; trace AI, group II; and mild AI, group III. RESULTS: Three hundred sixteen eligible patients underwent LVAD implant, 229 patients (72.5%) in group I, 54 (17.1%) in group II, and 33 (10.4%) in group III. Median follow-up was 469 days. Forty-two patients (13.3%) progressed to significant AI during follow-up. Group III patients had the highest rate of developing significant AI (I, 10.0%; II, 13.0%; III, 36.4%; P = .002). Freedom from significant AI at 1 year after LVAD implant was 94.5% in group I, 86.1% in group II, and 62.4% in group III (P < .001). Predictors of developing significant AI included mild preoperative AI, ischemic cardiomyopathy, and shorter duration of LVAD support. Patients with significant AI after LVAD implantation had higher mortality compared with those without (59.5% vs 37.2%; P = .006). CONCLUSIONS: Although some patients supported with an LVAD develop significant AI, this risk is increased in those with mild AI preoperatively. This finding, in conjunction with the increased mortality risk once significant AI develops, suggests that closer follow-up and management of LVAD patients with mild preoperative AI may be prudent.

Institutional volume affects long-term survival following lung transplantation in the USA.

OBJECTIVES: The aim of this study was to evaluate the impact of institutional volume on long-term outcomes following lung transplantation (LTx) in the USA. METHODS: Adults undergoing LTx were identified in the United Network for Organ Sharing registry. Patients were divided into equal size tertiles according to the institutional volume. All-cause mortality following LTx was evaluated using the risk-adjusted multivariable Cox regression and the Kaplan-Meier analyses, and compared between these volume cohorts at 3 points: 90 days, 1 year (excluding 90-day deaths) and 10 years (excluding 1-year deaths). Lowess smoothing plots and receiver-operating characteristic analyses were performed to identify optimal volume thresholds associated with long-term survival. RESULTS: A total of 13 370 adult LTx recipients were identified. The mean annual centre volume was 33.6 ± 20.1. After risk adjustment, low-volume centres were found to be at increased risk for 90-day mortality, [hazard ratio (HR) 1.56, P < 0.001], 1-year mortality excluding 90-day deaths (HR 1.46, P < 0.001) and 10-year mortality excluding 1-year deaths (HR 1.22, P < 0.001). These findings persisted when the centre volume was modelled as a continuous variable. The Kaplan-Meier analysis also demonstrated significant reductions in survival at each of these time points for low-volume centres (each P < 0.001). The 10-year survival conditional on 1-year survival was 37.4% in high-volume centres vs 28.0% in low-volume centres (P < 0.001). The optimal annual volume threshold for long-term survival was 26 LTx/year. CONCLUSIONS: The institutional volume impacts long-term survival following LTx, even after excluding deaths within the first post-transplant year. Identifying the processes of care that lead to longer survival in high-volume centres is prudent.

The impact of centre volume on outcomes of orthotopic heart transplant in older recipients.

OBJECTIVES: The aim of this study was to evaluate the impact of overall and older-recipient-specific centre volumes on outcomes of orthotopic heart transplant (OHT) in older recipients. METHODS: Patients aged ≥60 years undergoing OHT were identified in the United Network for Organ Sharing (UNOS) registry. The primary outcome was 1-year post-OHT mortality. Secondary outcomes included the incidence and impact on 1-year survival of postoperative complications including infection, renal failure requiring dialysis and stroke. Patients were divided into equal size tertiles based on overall and older-recipient-specific OHT centre volumes. RESULTS: A total of 5373 older recipients were identified. Mean overall and older-recipient-specific volumes were 27.5 ± 19.5 and 9.4 ± 7.3 OHT/year, respectively. Although overall and older-recipient-specific low-volume centres were at higher risk of mortality in separate multivariable analysis, only older-recipient-specific volume contributed significantly to post-OHT mortality in the combined multivariable analysis (P < 0.05). In the receiver operating characteristic analysis, an older-recipient-specific volume of 8 OHTs/year was identified as the most discriminative volume threshold for mortality (area under the receiver operating characteristic curve = 0.68). Although low older-recipient-specific volume centres did not have significantly higher incidences of postoperative complications, they had significantly worse 1-year survival rates compared to higher volume centres in patients with postoperative infection or dialysis (each P < 0.01). CONCLUSIONS: This large-cohort analysis demonstrates that older-recipient-specific centre volume contributes to post-OHT outcomes in the older recipients more significantly than overall volume. This may be a consequence of higher older-recipient-specific volume centres to better manage specific complications in this patient population.

Severe Dizziness and Syncope After HeartMate 3 Implantation Requiring Pump Exchange.

Implantation of the HeartMate 3 (HM3) left ventricular assist device (Abbott Laboratories, Lake Bluff, IL) continues to increase as the results of European and U.S. clinical trials become available. Although the large trials adequately capture the more common and expected outcomes, rare and unexpected clinical complications will continue to appear with higher volumes of implantation. This report describes a rare complication of severe refractory postural dizziness and syncope after successful implantation of an HM3 in a patient who ultimately required pump exchange to a HeartWare HVAD (HeartWare, Framingham, MA) for resolution of symptoms.

Repair of mitral periprosthetic leak secondary to severe annular calcification.

Hemolytic anemia due to a periprosthetic leak is a rare complication of valve replacement that has a poor prognosis. Herein are reported the details of two women (aged 62 and 74 years) who had undergone mitral valve surgery four times each; in both cases, a fifth operation was performed because of hemolytic anemia due to periprosthetic leak. An anterior repair of the leaks was performed instead of re-replacing the valve or standard repair, because the extensively calcified annulus led to sufficient space, and viable tissue was available to place direct sutures. Both patients made a rapid and uneventful recovery, with satisfactory short-term results; however, the long-term outcomes remain uncertain.

Quantum chemical studies of the myosin ATPase mechanism.

Muscle contraction is one of the molecular motions in the living body. The elemental process of muscle contraction is a mutual sliding of two kinds of filaments of proteins, myosin and actin, using energy liberated by ATP hydrolysis. Myosin enzymatically hydrolyzes ATP and interacts with actin. This article reviews previous quantum chemical studies to help determine how the chemical energy of ATP hydrolysis is converted to mechanical energy during sliding.

Midterm results of mitral valve repair with the Carpentier-Edwards rigid ring.

OBJECTIVE: Prosthetic annuloplasty rings play an important role in mitral valve repair. This clinical study was undertaken to evaluate the midterm results obtained with the Carpentier-Edwards rigid ring. METHODS: Between October 1991 and March 2005, 112 patients (mean age 53.0 years) underwent mitral valve repair with a Carpentier-Edwards rigid ring at our institution. Degenerative disease was the most frequent cause and a small number had other conditions such as endocarditis and rheumatic disease. Ten patients were in Carpentier's functional class Type I, 101 patients in Type II and 1 patient in Type III, based on valve pathology. Ischemic mitral regurgitation was excluded. The mean follow-up time was 5.3+/-3.6 years (range: 8 days to 12.3 years). All patients were completely followed by echocardiography. RESULTS: The rigid ring ranged from 26 to 36 mm in diameter and the most common size was 30 mm. Although the mitral orifice area was decreased after mitral valve repair in all patients, none of them required reoperation because of mitral stenosis or left ventricular outflow tract obstruction (systolic anterior motion). Reduction of both systolic and diastolic left ventricular volumes was observed postoperatively. Ejection fractions were preserved in all cases. The actuarial survival rate was 92.0+/-3.0% at 10 years and the reoperation-free rate at 10 years was 96.0+/-2.0%. CONCLUSION: The rigid ring has produced promising midterm results in terms of reoperation-free and survival rates.

Hemodynamic monitoring of large animal chronic studies after median sternotomy: experiences with different telemetric physiological devices.

Telemetric physiological monitoring systems (TPMS) have enabled accurate continuous measurement of animal blood pressures and flows. However, few studies describe approaches for use of TPMS in the great vessels or inside the heart. We describe our initial experiences using two types of TPMSs. Twelve lambs (20-37 kg) underwent sternotomy. Two lambs were not instrumented and were killed at 14 days to confirm normal sternal wound healing (sham group, n = 2). Ten lambs underwent placement of either standard indwelling pressure-monitoring catheter and perivascular-flow-probe (CFP group, n = 3) or TPMS implantation (TPMS group, n = 7). The TPMS used were EG1-V3S2T-M2 (EG1, n = 5; Transonic Endogear Inc.) and Physio Tel Digital L21 (PTD, n = 2; Data Sciences Inc.). Two deaths because of respiratory problems occurred in TPMS group, attributed to lung compression by the implanted device. In TPMS group, more consistent trends of blood pressures and flows were recorded, and management of animals was easier and less labor-intensive. Comparing the two TPMSs, the initiation and renewal costs for each case was $28 K vs. $20 K and $1,700 vs. $0, (PTD versus EG1, respectively). In conclusion, TPMS implantation was feasible via median sternotomy in lambs. Telemetric physiological monitoring systems significantly improve reliability of hemodynamic monitoring in chronic survival animal study. EG1 was less costly than PTD.