The Fontan immunophenotype and post-transplant outcomes in children: A multi-institutional study.

BACKGROUND: Patients after Fontan palliation represent a growing pediatric population requiring heart transplant (HTx) and often have lymphopenia (L) and/or hypogammaglobinemia that may be exacerbated by protein-losing enteropathy (PLE, P). The post-HTx effects of this altered immune phenotype are not well studied. METHODS: In this study of the Pediatric Heart Transplant Society Registry, 106 Fontan patients who underwent HTx between 2005 and 2018 were analyzed. The impact of lymphopenia and PLE on graft survival, infection, rejection, and malignancy was analyzed at 1 and 5 years post-HTx. RESULTS: The following combinations of lymphopenia and PLE were noted: +L+P, n = 37; +L-P, n = 23; -L+P, n = 10; and -L-P, n = 36. Graft survival between the groups was similar within the first year after transplant (+L+P: 86%, +L-P: 86%, -L+P: 87%, -L-P: 89%, p = .9). Freedom from first infection post-HTx was greatest among -L-P patients compared to patients with either PLE, lymphopenia, or both; with a 22.1% infection incidence in the -L-P group and 41.4% in all others. These patients had a significantly lower infection rate in the first year after HTx (+L+P: 1.03, +L-P: 1, -L+P: 1.3, -L-P: 0.3 infections/year, p < .001) and were similar to a non-single ventricle CHD control group (0.4 infections/year). Neither freedom from rejection nor freedom from malignancy 1 and 5 years post-HTx, differed among the groups. CONCLUSIONS: Fontan patients with altered immunophenotype, with lymphopenia and/or PLE, are at increased risk of infection post-HTx, although have similar early survival and freedom from rejection and malignancy. These data may encourage alternative immunosuppression strategies and enhanced monitoring for this growing subset of patients.

Quality of life and lifetime achievement in adult survivors of pediatric heart transplant.

BACKGROUND: Survival in pediatric heart transplantation has improved since the first successful transplant over 35 years ago leading to increasing numbers of patients entering adulthood. We sought to examine quality of life and various lifetime achievements in our institutional population of long-term adult survivors of pediatric heart transplant. METHODS: Participants ≥18 years of age who received a heart transplant as a pediatric patient (<18 years old), and who have survived ≥10 years post-transplant, completed two self-report surveys: (1) Ferrans and Powers QLI cardiac version which reports a measure of life satisfaction with a range of 0 (very dissatisfied) to 1 (very satisfied); and (2) CHONY Pediatric Heart Transplant Life Achievement Survey to examine lifetime achievement. RESULTS: Sixty-two and sixty-five participants completed the Ferrans and Powers QLI cardiac version and CHONY Pediatric Heart Transplant Life Achievement Survey. The mean overall QLI was 0.75 ± 0.14 with the most satisfaction in the family domain. QLI scores were analyzed by age at initial transplant, gender, indication for transplant, and whether patients currently followed by pediatric or adult providers, with no statistically significant differences noted. Seventy-two percent of participants demonstrated stable employment or schooling. Around thirty percent of participants showed the ability to reach academic milestones including college and post-graduate education and ten percent to start their own families. CONCLUSIONS: Our cohort of long-term adult survivors of pediatric heart transplant report a quality of life with scores thought to be reflective of a satisfactory quality of life, and many demonstrate achievement of major life milestones.

Evolution of pediatric ventricular assist devices and their neurologic and renal complications-A 24-year single-center experience.

Utilization of ventricular assist devices (VADs) in adult populations with severe heart failure as a bridge to transplant has become the standard of care over the past two decades. Analogously, the use of VADs in pediatric populations has become more commonplace as pediatric heart transplantation has become more prevalent. We still have much to learn, however, about the complications after VAD placement in pediatric patients, their impact on transplantation and, in particular, how outcomes have changed over time. The objectives of this study were to (a) review the experience of a single pediatric VAD center, (b) identify risk factors that could lead to poor outcomes in patients on the transplant waitlist after VAD implantation and (c) demonstrate changes in outcomes over time. A retrospective cohort analysis was performed comparing death as a primary outcome and stroke and acute kidney injury (AKI) as secondary outcomes, across the study period divided into three timed eras. We analyzed 88 patients supported by a VAD over a 24-year timeframe. The duration, age at implant and indication for VAD support did not change significantly across the eras. We found that the incidence of stroke decreased over the study period and, while the rates of AKI did not change over the study period, those who developed AKI, while supported on VAD, had an increased risk of death.

Biventricular Impella use in pediatric patients with severe graft dysfunction from acute rejection after heart transplantation.

Rejection with severe hemodynamic compromise is a significant source of morbidity and mortality for pediatric heart transplant patients. Traditionally, treatment for these patients includes inotropes and escalation to extracorporeal membrane oxygenation (ECMO) when necessary. There is increasing interest in using percutaneous ventricular assistive devices in the pediatric population as a less invasive alternative to ECMO. We report the largest case series to date of biventricular support using percutaneous Impella devices. Retrospective case series was performed by chart review. Hemodynamics, left ventricular ejection fraction (LVEF), and indices of end organ function were collected before and after Impella placement. A 14-year-old male, 18-year-old male, and 19-year-old female, all status post heart transplant, presented with severely decreased biventricular function due to presumed clinical rejection, requiring maximal inotropic support without improvement. In all the three cases, simultaneous Impella CP and RP devices were placed percutaneously. Prior to implantation, LVEFs were 40%, 23%, and 25%, respectively. Hemodynamics measured invasively prior to device placement showed elevated filling pressures. Adverse events while on support included bleeding, hemolysis, and right femoral arterial dissection during implantation. All patients were successfully weaned from the devices and survived to discharge. The average time of right-sided support and total support was 11 days and 13 days, respectively. After device removal, right-sided pressures and echocardiographic measurements showed improvement in all patients. Bilateral Impella configuration (BiPella) is a viable option for temporary mechanical circulatory support in pediatric patients with significant graft dysfunction.

Prospective Study of Adenosine on Atrioventricular Nodal Conduction in Pediatric and Young Adult Patients After Heart Transplantation.

BACKGROUND: Supraventricular tachycardia is common after heart transplantation. Adenosine, the standard therapy for treating supraventricular tachycardia in children and adults without transplantation, is relatively contraindicated after transplantation because of a presumed risk of prolonged atrioventricular block in denervated hearts. This study tested whether adenosine caused prolonged asystole after transplantation and if it was effective in blocking atrioventricular nodal conduction in these patients. METHODS: This was a single-center prospective clinical study including healthy heart transplant recipients 6 months to 25 years of age presenting for routine cardiac catheterization during 2015 to 2016. After catheterization, a transvenous pacing catheter was placed and adenosine was given following a dose-escalation protocol until atrioventricular block was achieved. The incidence of clinically significant asystole (≥12 seconds after adenosine) was quantified. The effects of patient characteristics on adenosine dose required to produce atrioventricular block and duration of effect were also measured. RESULTS: Eighty patients completed adenosine testing. No patient (0%; 95% confidence interval, 0-3) required rescue ventricular pacing. Atrioventricular block was observed in 77 patients (96%; 95% confidence interval, 89-99). The median longest atrioventricular block was 1.9 seconds (interquartile range, 1.4-3.2 seconds), with a mean duration of adenosine effect of 4.3±2.0 seconds. No patient characteristic significantly predicted the adenosine dose to produce atrioventricular block or duration of effect. Results were similar across patient weight categories. CONCLUSIONS: Adenosine induces atrioventricular block in healthy pediatric and young adult heart transplant recipients with minimal risk when low initial doses are used (25 µg/kg; 1.5 mg if ≥60 kg) and therapy is gradually escalated. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02462941.

Bivalirudin Compared to Heparin as the Primary Anticoagulant in Pediatric Berlin Heart Recipients.

Bivalirudin has been used in increasing frequency as an alternative to unfractionated heparin (UFH) in pediatric recipients of Berlin Heart EXCOR ventricular assist devices (VAD). This single-center, retrospective review characterizes anticoagulant trends and outcomes in pediatric Berlin Heart VAD recipients implanted between September 1, 2013, and August 31, 2021, anticoagulated with either bivalirudin or UFH. Thirty-one patients were included; 65% who received bivalirudin and 35% who received UFH. The median age was 2.9 years, included 64.5% females, with 61.3% of patients diagnosed with dilated cardiomyopathy and 25.8% of patients with congenital heart disease. Therapeutic anticoagulation was achieved sooner in the bivalirudin group compared to UFH via anti-Xa monitoring (median 5.7 and 69.5 hours, respectively, p < 0.001). Bivalirudin had a greater number of therapeutic values comparatively to UFH (52% and 24%, respectively; p < 0.001) and a superior number of hours in the therapeutic range (67% and 32%, respectively; p < 0.001). Secondary outcomes were similar among the two groups, apart from greater chest tube output (UFH), more frequent events of elevated plasma-free hemoglobin (bivalirudin), and more frequent elevated inflammatory markers postimplant (bivalirudin). Prevalence of pump replacements secondary to significant clot burden and prevalence of stroke was comparable. In this patient cohort, bivalirudin demonstrated greater anticoagulation stability comparatively to UFH. Multicenter collaboration would be necessary to identify whether this further translates into improved patient outcomes.