Gordon A. Cohen

Prospective Trial of a Pediatric Ventricular Assist Device

BACKGROUND Options for mechanical circulatory support as a bridge to heart transplantation in children with severe heart failure are limited. METHODS We conducted a prospective, single-group trial of a ventricular assist device designed specifically for children as a bridge to heart transplantation. Patients 16 years of age or younger were divided into two cohorts according to body-surface area (cohort 1, <0.7 m(2); cohort 2, 0.7 to <1.5 m(2)), with 24 patients in each group. Survival in the two cohorts receiving mechanical support (with data censored at the time of transplantation or weaning from the device owing to recovery) was compared with survival in two propensity-score-matched historical control groups (one for each cohort) undergoing extracorporeal membrane oxygenation (ECMO). RESULTS For participants in cohort 1, the median survival time had not been reached at 174 days, whereas in the matched ECMO group, the median survival was 13 days (P<0.001 by the log-rank test). For participants in cohort 2 and the matched ECMO group, the median survival was 144 days and 10 days, respectively (P<0.001 by the log-rank test). Serious adverse events in cohort 1 and cohort 2 included major bleeding (in 42% and 50% of patients, respectively), infection (in 63% and 50%), and stroke (in 29% and 29%). CONCLUSIONS Our trial showed that survival rates were significantly higher with the ventricular assist device than with ECMO. Serious adverse events, including infection, stroke, and bleeding, occurred in a majority of study participants. (Funded by Berlin Heart and the Food and Drug Administration Office of Orphan Product Development; ClinicalTrials.gov number, NCT00583661.).

Berlin Heart EXCOR Pediatric Ventricular Assist Device for Bridge to Heart Transplantation in US Children

Background— Recent data suggest that the Berlin Heart EXCOR Pediatric ventricular assist device is superior to extracorporeal membrane oxygenation for bridge to heart transplantation. Published data are limited to 1 in 4 children who received the device as part of the US clinical trial. We analyzed outcomes for all US children who received the EXCOR to characterize device outcomes in an unselected cohort and to identify risk factors for mortality to facilitate patient selection. Methods and Results— This multicenter, prospective cohort study involved all children implanted with the Berlin Heart EXCOR Pediatric ventricular assist device at 47 centers from May 2007 through December 2010. Multiphase nonproportional hazards modeling was used to identify risk factors for early (<2 months) and late mortality. Of 204 children supported with the EXCOR, the median duration of support was 40 days (range, 1–435 days). Survival at 12 months was 75%, including 64% who reached transplantation, 6% who recovered, and 5% who were alive on the device. Multivariable analysis identified lower weight, biventricular assist device support, and elevated bilirubin as risk factors for early mortality and bilirubin extremes and renal dysfunction as risk factors for late mortality. Neurological dysfunction occurred in 29% and was the leading cause of death. Conclusions— Use of the Berlin Heart EXCOR has risen dramatically over the past decade. The EXCOR has emerged as a new treatment standard in the United States for pediatric bridge to transplantation. Three-quarters of children survived to transplantation or recovery; an important fraction experienced neurological dysfunction. Smaller patient size, renal dysfunction, hepatic dysfunction, and biventricular assist device use were associated with mortality, whereas extracorporeal membrane oxygenation before implantation and congenital heart disease were not.

Bridging children of all sizes to cardiac transplantation: The initial multicenter North American experience with the Berlin Heart EXCOR ventricular assist device

BACKGROUND Beginning in 2000 and accelerating in 2004, the Berlin Heart EXCOR (Berlin Heart Inc Woodlands, TX) became the first pediatric-specific ventricular assist device (VAD) applied throughout North America for children of all sizes. This retrospective study analyzed the initial Berlin Heart EXCOR pediatric experience as a bridge to transplantation. METHODS Between June 2000 and May 2007, 97 EXCOR VADs were implanted in North America at 29 different institutions. The analysis is limited to 73 patients (75%) from 17 institutions, for which retrospective data were available. RESULTS Median age and weight at VAD implant were 2.1 years (range, 12 days-17.8 years) and 11 kg (range, 3-87.6 kg), respectively. The primary diagnoses were dilated cardiomyopathy in 42 (58%), congenital heart disease in 19 (26%), myocarditis in 7 (10%), and other cardiomyopathies in 5 (7%). Pre-implant clinical condition was critical cardiogenic shock in 38 (52%), progressive decline in 33 (45%), or other in 2 (3%). Extracorporeal membrane oxygenation was used as a bridge to EXCOR in 22 patients (30%). Device selection was left VAD (LVAD) in 42 (57%) and biventricular assist devices (BiVAD) in 31 (43%). The EXCOR bridged 51 patients (70%) to transplant and 5 (7%) to recovery. Mortality on the EXCOR was 23% (n = 17) overall, including 35% (11 of 31) in BiVAD vs 14% (6 of 42) in LVAD patients (p = 0.003). Multivariate analysis showed younger age and BiVAD support were significant risk factors for death while on the EXCOR. CONCLUSIONS This limited but large preliminary North American experience with the Berlin Heart EXCOR VAD as a bridge to cardiac transplantation for children of all ages and sizes points to the feasibility of this approach. The prospective investigational device evaluation trial presently underway will further characterize the safety and efficacy of the EXCOR as a bridge to pediatric cardiac transplantation.

The waiting game: bridging to paediatric heart transplantation

BACKGROUND Although mechanical circulatory support might not increase the number of adults surviving to transplantation, because of the shortage of donor organs, the situation might be different for children. Our aim was to assess the effect of mechanical assist devices to bridge children with end-stage cardiomyopathy to heart transplantation. METHODS A 5-year retrospective review was undertaken with data from the UK paediatric transplant programme and from bridging to transplant done at two paediatric transplant centres in the UK. FINDINGS Between Jan 1, 1998 and Dec 31, 2002, 22 children with end-stage cardiomyopathy, median age 5.7 years (range 1.2-17), were supported by a mechanical assist device as a bridge to first heart transplantation, with a 77% survival rate to hospital discharge. Nine were supported by a paracorporeal ventricular assist device, six received transplantation, five survived to discharge (55%), with one late death. 13 were supported by extra-corporeal membrane oxygenation, and 12 were transplanted and survived to discharge (92%) with one late death. With urgent listing, the median waiting time for a heart was 7.5 days (range 1.5-22 days). The correlation between the proportion of patients bridged to transplantation and the proportion of patients dying while on the transplant waiting list was r=-0.93, p=0.02. INTERPRETATION Our findings lend support to the hypothesis that a national mechanical assist programme to bridge children to transplantation can minimise the number dying while on the heart transplant waiting list. In the context of urgent listing and a short waiting time, extra-corporeal membrane oxygenation seems to provide the safest form of support.

Triiodothyronine Supplementation in Infants and Children Undergoing Cardiopulmonary Bypass (TRICC) A Multicenter Placebo-Controlled Randomized Trial: Age Analysis

Background— Triiodothyronine levels decrease in infants and children after cardiopulmonary bypass. We tested the primary hypothesis that triiodothyronine (T3) repletion is safe in this population and produces improvements in postoperative clinical outcome. Methods and Results— The TRICC study was a prospective, multicenter, double-blind, randomized, placebo-controlled trial in children younger than 2 years old undergoing heart surgery with cardiopulmonary bypass. Enrollment was stratified by surgical diagnosis. Time to extubation (TTE) was the primary outcome. Patients received intravenous T3 as Triostat (n=98) or placebo (n=95), and data were analyzed using Cox proportional hazards. Overall, TTE was similar between groups. There were no differences in adverse event rates, including arrhythmia. Prespecified analyses showed a significant interaction between age and treatment (P=0.0012). For patients younger than 5 months, the hazard ratio (chance of extubation) for Triostat was 1.72. (P=0.0216). Placebo median TTE was 98 hours with 95% confidence interval (CI) of 71 to 142 compared to Triostat TTE at 55 hours with CI of 44 to 92. TTE shortening corresponded to a reduction in inotropic agent use and improvement in cardiac function. For children 5 months of age, or older, Triostat produced a significant delay in median TTE: 16 hours (CI, 7-22) for placebo and 20 hours (CI, 16-45) for Triostat and (hazard ratio, 0.60; P=0.0220). Conclusions— T3 supplementation is safe. Analyses using age stratification indicate that T3 supplementation provides clinical advantages in patients younger than 5 months and no benefit for those older than 5 months. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00027417.

Pitfalls of adverse event reporting in paediatric cardiac intensive care

Aims: To evaluate the pitfalls of incident reporting in a complex medical environment. Methods: Retrospective review of 211 incident reports in a paediatric cardiac intensive care unit (CICU). Two adverse event reporting databases were compared: database A (DA), the hospital’s official reporting system, is non-anonymous and reports are predominantly made by nurses; database B (DB) is anonymous and reports are submitted by a CICU consultant who collects data from daily ward rounds. Both databases classify adverse events into incident type (drug errors, ventilation, cannulae/indwelling lines, chest drains, blood transfusion, equipment, operational) and severity (0 = no, 1 = minor, 2 = major, 3 = life threatening consequences). Results: Between 1 April 1998 and 31 July 2001 there were 211 adverse events involving 178 patients (11.87%), among 1500 patients admitted to CICU. A total of 112 incidents were reported in DA, 143 in DB, and 44 in both. In isolation, both databases gave an unrepresentative picture of the true frequency and severity of adverse events. Under-reporting was especially notable for less severe events (grade 0, or near misses) Conclusion: Incident reporting in the medical field is highly variable, and is heavily influenced by profession of the reporters as well as anonymity. When adverse event reporting is based predominantly on the observations of a single professional group, the data are grossly inaccurate.

Superior cardiac function via anaplerotic pyruvate in the immature swine heart after cardiopulmonary bypass and reperfusion

Pyruvate produces inotropic responses in the adult reperfused heart. Pyruvate oxidation and anaplerotic entry into the tricarboxylic acid (TCA) cycle via carboxylation are linked to the stimulation of contractile function. The goals of this study were to determine if these metabolic pathways operate and are maintained in the developing myocardium after reperfusion. Immature male swine (age: 10-18 days) were subjected to cardiopulmonary bypass (CPB). Intracoronary infusion of [2-(13)C]pyruvate (to achieve an estimated final concentration of 8 mM) was given for 35 min, starting either during weaning (group I) and after its discontinuation (group II) or without (control) CPB. Hemodynamic data were collected. 13C NMR spectroscopy was used to determine the fraction of pyruvate entering the TCA cycle via pyruvate carboxylation (PC) to total TCA cycle entry (PC plus decarboxlyation via pyruvate dehydrogenase). Liquid chromatography-mass spectrometry was used to determine total glutamate enrichment. Pyruvate infusion starting during the weaning of mechanical circulatory support improved maximum dP/dt (P<0.05) but waiting to start the infusion until after the discontinuation of CPB did not. Glutamate fractional enrichment was confirmed by liquid chromatography-mass spectroscopy as adequate (>5%) to provide signal to noise in the NMR experiment in all groups. The ratio of pyruvate carboxylase to total pyruvate entry into the TCA cycle did not differ between groups (group I: 20+/-4%, group II: 23+/-7%, and control: 27+/-7%). These data show that robust PC operates in the neonatal pig heart and is maintained during reperfusion under conditions that emulate CPB and reperfusion in human infants.

Congenital cardiac surgical complications of the integument, vascular system, vascular-line(s), and wounds: consensus definitions from the Multi-Societal Database Committee for Pediatric and Congenital Heart Disease

A complication is an event or occurrence that is associated with a disease or a healthcare intervention, is a departure from the desired course of events, and may cause, or be associated with, suboptimal outcome. A complication does not necessarily represent a breech in the standard of care that constitutes medical negligence or medical malpractice. An operative or procedural complication is any complication, regardless of cause, occurring (1) within 30 days after surgery or intervention in or out of the hospital, or (2) after 30 days during the same hospitalization subsequent to the operation or intervention. Operative and procedural complications include both intraoperative/intraprocedural complications and postoperative/postprocedural complications in this time interval. The MultiSocietal Database Committee for Pediatric and Congenital Heart Disease has set forth a comprehensive list of complications associated with the treatment of patients with congenital cardiac disease, related to cardiac, pulmonary, renal, haematological, infectious, neurological, gastrointestinal, and endocrinal systems, as well as those related to the management of anaesthesia and perfusion, and the transplantation of thoracic organs. The objective of this manuscript is to examine the definitions of operative morbidity as they relate specifically to a collection of loosely related topics that include the following groups of complications: 1) Complications of the Integument, 2) Complications of the Vascular System, 3) Complications of the Vascular-Line(s), 4) Complications of Wounds. These specific definitions and terms will be used to track morbidity associated with surgical and transcatheter interventions and other forms of therapy in a common language across many separate databases. As surgical survival in children with congenital cardiac disease has improved in recent years, focus has necessarily shifted to reducing the morbidity of congenital cardiac malformations and their treatment. A comprehensive list of complications is presented. This list is a component of a systems-based compendium of complications that will standardize terminology and thereby allow the study and quantification of morbidity in patients with congenital cardiac malformations. Clinicians caring for patients with congenital cardiac disease will be able to use this list for databases, initiatives to improve quality, reporting of complications, and comparing strategies of treatment.

Association of thymectomy with infection following congenital heart surgery.

Background: Congenital absence of the thymus can lead to profound immunodeficiency, suggesting that thymic function during fetal development is essential to normal lymphocyte development. How vital the thymus after birth is to human immune competence and regulation is not known. Routine thymectomy, especially at an early age, may influence immunity, and therefore the risk of infection, autoimmunity, or malignancy. Methods: A retrospective review of cardiac surgery patients followed at Seattle Children’s Hospital was performed. The primary outcome was rate of serious infections requiring hospitalization. Secondary analyses included age, type of infection, cardiac diagnosis, surgical procedure, and comorbidities. Results: Patients fell into 2 groups: 60 with complete thymectomy and 35 with partial or no thymectomy. There was no statistical difference between groups in the overall prevalence of serious infections (16.7% vs 17.2%, P = 1.0). There was a nonsignificant trend toward reduced time between surgery and onset of first infection in patients in the total thymectomy group versus those without thymectomy (1.7 years vs 4.6 years, P = .07). Total thymectomy before 6 months of age also tended to increase infection rate, but the effect was not significant (0.09/year vs 0.02, P = .14). Gastroesophageal reflux in patients with total thymectomy increased the risk of infection (P = .013), suggesting a cumulative effect. Conclusions: Though infections occurred frequently in the childhood cardiac surgery population, total thymectomy was not associated with increased risk of serious infection. Comorbid conditions may be more important contributing factors increasing the risk of infection in this complex and vulnerable population.

Sternal wire removal in pediatric patients: Wire versus cable sternotomy closure

*Difference statistically significant by Fisher exact test (P 1⁄4 .008). Secure sternal closure after median sternotomy is important to facilitate sternal healing, optimize ventilatory mechanics, and minimize discomfort in the early postoperative period. Many techniques have been reported for sternal closure in adults, with the most widely used involving permanent stainless steel wires or cables. In the pediatric population, absorbable sutures may be used in smaller patients, but stainless steel wire or cable closure is generally preferred for larger children and teens. Although uncommon, persistent chest wall pain related to sternal wire closure is well described in the adult population and may necessitate reoperation for wire removal. This finding has not been described after cable closure in adults. Furthermore, the frequency of persistent pain after sternal closure with either wire or cable systems in children is unknown. Beginning in March 2005, a cable system was used for sternal closure in all patients larger than 30 kg at our institution. A seemingly disproportionate rate of reoperation for cable removal was subsequently observed. We therefore reviewed our institutional experience with wire and cable sternal closures to compare the performances of these sternal closure systems in the pediatric population.