Mechanical Circulatory Support of the Critically Ill Child Awaiting Heart Transplantation

The majority of children awaiting heart transplantation require inotropic support, mechanical ventilation, and/or extracorporeal membrane oxygenation (ECMO) support. Unfortunately, due to the limited pool of organs, many of these children do not survive to transplant. Mechanical circulatory support of the failing heart in pediatrics is a new and rapidly developing field world-wide. It is utilized in children with acute congestive heart failure associated with congenital heart disease, cardiomyopathy, and myocarditis, both as a bridge to transplantation and as a bridge to myocardial recovery. The current arsenal of mechanical assist devices available for children is limited to ECMO, intra-aortic balloon counterpulsation, centrifugal pump ventricular assist devices, the DeBakey ventricular assist device Child; the Thoratec ventricular assist device; and the Berlin Heart. In the spring of 2004, five contracts were awarded by the National Heart, Lung and Blood Institute to support preclinical development for a range of pediatric ventricular assist devices and similar circulatory support systems. The support of early development efforts provided by this program is expected to yield several devices that will be ready for clinical trials within the next few years. Our work reviews the current international experience with mechanical circulatory support in children and summarizes our own experience since 2005 with the Berlin Heart, comparing the indications for use, length of support, and outcome between these modalities

The impact of heart failure severity at time of listing for cardiac transplantation on survival in pediatric cardiomyopathy

BACKGROUND: The survival benefit of heart transplantation in adult heart failure is greatest for the sickest patients and negligible for patients not requiring inotropic or mechanical support. We hypothesized a similar survival benefit of heart transplantation for childhood cardiomyopathies with heart failure. METHODS: A merged dataset of children registered in both the Pediatric Cardiomyopathy Registry and the Pediatric Heart Transplant Study was used to assess differences in mortality before and after transplant in patients with different levels of heart failure severity. Severity was scored 2 if mechanical ventilatory or circulatory support was required, 1 if intravenous inotropes were required, or 0 if no support was required. RESULTS: For 332 eligible children, 12-month mortality after listing was 9% for those with a severity score of 0 (n=105), 16% with a score of 1 (n=118), and 26% with a score of 2 (n=109; P=0.002) with a 3%, 8%, and 20% mortality with severity scores at listing of 0, 1, and 2, respectively, occurring before transplant. Patients listed with a score of 0 frequently deteriorated: 50% were transplanted or died prior to transplant with severity scores of 1 or 2. The risk of deterioration increased with previous surgery (relative risk, 3.84; P=0.03) in the short-term and with lower left ventricular mass z-score at time of presentation (relative risk, 1.74; P=0.003) in the longer-term. CONCLUSION: Pediatric cardiomyopathy patients who require high levels of support receive a survival benefit from heart transplantation that is not shared by patients not requiring intravenous inotropic or mechanical support

The Pediatric Cardiomyopathy Registry and Heart Failure: Key Results from the First 15 Years

Cardiomyopathy is a serious disorder of the heart muscle and, although rare, is a common cause of heart failure in children and the most common cause for heart transplantation in children older than 1 year of age. Funded by the National Heart Lung and Blood Institute since 1994, the Pediatric Cardiomyopathy Registry (PCMR) has followed more than 3500 North American children with cardiomyopathy. Early analyses determined estimates for the incidence of pediatric cardiomyopathy (1.13 cases per 100,000 children per year), risk factors for cardiomyopathy (age less than 1 year, male sex, black race, and living in New England as opposed to the Central Southwestern states), the prevalence of heart failure at diagnosis (6%–84% depending on cause), and 10-year survival (29%–94% depending on cause). More recent analyses explored cause-specific functional status, survival and transplant outcomes, and risk factors in greater detail. For many topics these analyses are based on the largest and best-documented samples of children with disease such as the muscular dystrophies, mitochondrial disorders, and Noonan’s syndrome. Data from the PCMR continue to provide valuable information that guides clinical management and the use of life-saving therapies, such as cardiac transplantation and approaches to treating heart failure, and that prepares children, their families, and their caregivers for dealing with this serious condition

The impact of heart failure severity at time of listing for cardiac transplantation on survival in pediatric cardiomyopathy

The survival benefit of heart transplantation in adult heart failure is greatest for the sickest patients and negligible for patients not requiring inotropic or mechanical support. We hypothesized a similar survival benefit of heart transplantation for childhood cardiomyopathies with heart failure. A merged data set of children registered in both the Pediatric Cardiomyopathy Registry and the Pediatric Heart Transplant Study was used to assess differences in mortality before and after transplant in patients with different levels of heart failure severity. Severity was scored 2 if mechanical ventilatory or circulatory support was required, 1 if intravenous inotropes were required, or 0 if no support was required. For 332 eligible children, 12-month mortality after listing was 9% for those with a severity score of 0 ( n = 105), 16% with a score of 1 ( n = 118), and 26% with a score of 2 ( n = 109; p = 0.002) with a 3%, 8%, and 20% mortality with severity scores at listing of 0, 1, and 2, respectively, occurring before transplant. Patients listed with a score of 0 frequently deteriorated: 50% received an allograft or died before transplant with severity scores of 1 or 2. The risk of deterioration increased with previous surgery (relative risk, 3.84; p = 0.03) in the short-term and with lower left ventricular mass z-score at time of presentation (relative risk, 1.74; p = 0.003) in the longer-term. Pediatric cardiomyopathy patients who require high levels of support receive a survival benefit from heart transplantation that is not shared by patients not requiring intravenous inotropic or mechanical support

Early Predictors of Survival to and After Heart Transplantation in Children With Dilated Cardiomyopathy

Background— The importance of clinical presentation and pretransplantation course on outcome in children with dilated cardiomyopathy listed for heart transplantation is not well defined. Methods and Results— The impact of age, duration of illness, sex, race, ventricular geometry, and diagnosis of myocarditis on outcome in 261 children with dilated cardiomyopathy enrolled in the Pediatric Cardiomyopathy Registry and Pediatric Heart Transplant Study was studied. End points included listing as United Network for Organ Sharing status 1, death while waiting, and death after transplantation. The median age at the time of diagnosis was 3.4 years, and the mean time from diagnosis to listing was 0.62±1.3 years. Risk factors associated with death while waiting were ventilator use and older age at listing in patients not mechanically ventilated ( P =0.0006 and P =0.03, respectively). Shorter duration of illness ( P =0.04) was associated with listing as United Network for Organ Sharing status 1. Death after transplantation was associated with myocarditis at presentation ( P =0.009), nonwhite race ( P <0.0001), and a lower left ventricular end-diastolic dimension z score at presentation ( P =0.04). In the myocarditis group, 17% (4 of 23) died of acute rejection after transplantation. Conclusions— Mechanical ventilator use and older age at listing predicted death while waiting, whereas nonwhite race, smaller left ventricular dimension, and myocarditis were associated with death after transplantation. Although 97% of children with clinically or biopsy-diagnosed myocarditis at presentation survived to transplantation, they had significantly higher posttransplantation mortality compared with children without myocarditis, raising the possibility that preexisting viral infection or inflammation adversely affects graft survival