Heart disease, both congenital and acquired, in children and adolescents is common, approaching 1% of the population. Fortunately, most have simple lesions with normal exercise tolerance. However, in those pediatric patients with complex physiology and severe cardiac dysfunction, the inability to participate in physical activity results in significant obstacles to normal acts of daily living and significantly diminished quality of life. Although there have been numerous attempts to study the practicality and benefits of cardiopulmonary rehabilitation (CR) programs in this population, they have generally been hampered by the heterogeneity of any particular lesion, the lack of facilities designed for children, access and geographic proximity to rehabilitation centers, and trained personnel to supervise these types of programs. As such, although there are numerous articles on CR in children with cardiac disease, all suffer from the same basic problems of small sample size, short duration of study.
The purposes of this review were first to review the current rehabilitation literature on both congenital cardiac defects and acquired abnormalities. In this latter group, we placed significant emphasis on cardiomyopathies, as well as the special populations in the peri-transplant period and/or those patients requiring intermediate or long-term mechanical circulatory support. Second, we discussed what is known about practical approaches to CR for the various types of pediatric-specific cardiac conditions. This included the current approach of our institution to CR in these populations with the understanding that this is by no means a consensus approach to these patients. Finally, we summarized research goals for this growing group of patients.
REVIEW OF RELEVANT LITERATURE
EXERCISE PERFORMANCE IN CONGENITAL HEART DISEASE
There are no definitive reference values for exercise performance in pediatric congenital heart disease (CHD), and significant heterogeneity exists based on the complexity of each lesion. Table 1 illustrates the relative comparison of several CHD lesions to otherwise normal cardiac physiology in terms of overall exercise performance and the diagnostic features driving potential clinical reasons for referral to the clinical exercise physiology laboratory.1 It illustrates that in the presence of simple biventricular CHD (ie, atrial septal defect), exercise performance is normal or near-normal. However, more complex lesions, including single ventricle physiology, often result in mild-to-moderately decreased peak oxygen uptake (V˙o2peak).2,3 Therefore, the importance of assessing exercise performance in the CHD population provides insight into clinical decision-making and provides a basis for referral to CR and exercise training.
Table 1 -
Clinical Comparison to Normative Data and Diagnostic Rationale for Exercise Testing in Children and Adolescents With Congenital or Acquired Heart Diseasea
||Percent of Predicted Normative Data (%)
||Indications for Testing
|Simple shunt lesions
|Atrial septal defect
||RV dysfunction or dilation effect on performance, atrial arrhythmias, sinus node dysfunction
|Ventricular septal defect
||LV dysfunction or dilation effect on performance, ventricular arrhythmias
|Coarctation of the aorta
||Systemic hypertension, assess upper-to-lower blood pressure gradient
||Myocardial ischemia, blood pressure response, left ventricular outflow track obstruction (stress echocardiography)
||Myocardial ischemia, blood pressure response, ventricular arrhythmias, left ventricular outflow track obstruction (stress echocardiography)
|Complex cyanotic physiology
|Transposition of the great arteries
||Myocardial ischemia, chronotropic response
|Tetralogy of Fallot
||RV dysfunction or dilation effect on performance, ventricular arrhythmias, residual abnormalities in lung function
|Single ventricle physiology
||Reduced exercise performance due to decreased stroke volume and musculoskeletal deficits in mass, arterial oxygen saturation, chronotropic response
Abbreviations: LV, left ventricle; RV, right ventricle.
Adapted from Edelson et al (2019).1
EXERCISE REHABILITATION IN CONGENITAL HEART DISEASE
All attempts at CR programs in CHD share the common goals of improving physical functioning and quality of life. In children with CHD, exercise training may also provide confidence to participate in or return to competitive or recreational sport, an opportunity often not available in the adult population. Research in the area of CR and exercise training in CHD suffers from significant limitations. Weaknesses in study design are common and include high dropout rates, variable duration, lack of sufficient follow-up time, and variable outcome measures.4–15 Most importantly there are almost always heterogeneous subject populations and all lack of adequate control groups.
Table 2 summarizes a variety of attempts at assessing the effects of CR over the past two decades, demonstrating that between 2 and 3 sessions/wk can increase work efficiency in patients with heart failure (HF) awaiting transplant, skeletal muscle function, V˙o2peak, oxygen pulse, and 6-min walk test distance in patients with Fontan physiology, V˙o2 and workload in children with tetralogy of Fallot, and V˙o2, work rate, and anaerobic threshold (AT) in a heterogeneous group of patients with CHD. Most studies, especially earlier ones, include a wide variety of complex repaired or palliated defects such as tetralogy of Fallot, D-transposition of the great arteries, and atrioventricular canal defects, as well as simpler defects such as atrial and ventricular septal defects. These also frequently include subjects with single ventricle physiology palliated with the Fontan operation. This approach results in wide discrepancies in the baseline functional characteristics of these study populations. The small number of any given individual defect within the study population prevents adequate assessment of the intervention on those individual defects. Even within studies that have a limited type of defect, the significant heterogeneity within the type of defect can be problematic. For example, there is a great degree of variability in the cardiopulmonary capacity of patients who have undergone an operation for tetralogy of Fallot, with their exercise capacities ranging from extremely limited to occasionally above the normal range for the healthy population.
Table 2 -
Cardiac Rehabilitation and Exercise Training in Pediatric
Congenital Heart Disease
|McBride et al (2007)4
||Heart failure awaiting TX
||13 ± 3.2
||3 sessions/wk aerobic and resistance
||Increased work efficiency (10%)
|Duppen et al (2015)12
||CHD and acquired heart disease
||4-5 sessions/wk aerobic
||Increased V˙o2 (20%) and TM time (21%)
|Brassard et al (2006)8
||3 sessions/wk aerobic and resistance (↓ resting SBP 9 mm Hg)
||Improved skeletal muscle function
|Hedlund et al (2016)16
||3 sessions/wk aerobic
||Improved V˙o2 (5%)
|Longmuir et al (1991)11,a
|Opocher et al (2005)9
||2 sessions/wk home training 2 times/wk
||Improved V˙o2 (15%)
Increased O2P (19%)
|Rhodes et al (2005, 2006)5,6
||2 sessions/wk aerobic and resistance
||Improved V˙o2 (14%)
Improved work (12%)
Improved VAT (18%)
|Avitabile et al (2014)17 and Kirk et al (2014)18
||2 sessions/wk aerobic
||Improved V˙o2 (11%)
Increased O2P (12%)
Abbreviations: 6MWT, 6-min walk test; CHD, congenital heart disease; DCM, dilated cardiomyopathy; O2P, oxygen pulse; SBP, systolic blood pressure; TOF, tetralogy of Fallot; TM, treadmill; TX, transplant; VAT, ventilatory anaerobic threshold; V˙o2, oxygen uptake.
aData unavailable in online text.
The structure of CR used in these studies also varies considerably as to the intensity, duration, and frequency of exercise. Prior to 2005, most pediatric CR programs employed aerobic exercise training using cycle or treadmill ergometry in an effort to improve central cardiovascular function.6,9,10 More recently, several programs and studies have offered a combination of aerobic and resistance exercises as part of their CR program, with the understanding that peripheral factors play a greater role in the rehabilitation of children with central cardiovascular abnormalities.4,7,9,19,20 Perhaps, most importantly, is the recent recognition of the need for a fundamentally different approach to CR and training in those patients with a single ventricle as opposed to a two-ventricle physiology.
In the Fontan palliation of single ventricle heart disease, the superior and inferior vena cavae are directly anastomosed to the pulmonary arteries resulting in the lack of a subpulmonary ventricle. Pulmonary blood flow and hence systemic ventricular pre-load are dependent on the gradient from the central venous pressure to the systemic atrial pressure. Interventions that improve the ability to augment this gradient during exercise by either improving systemic venous tone and/or decreasing pulmonary vascular resistance will result in improved cardiorespiratory fitness (CRF) in this population. In the Fontan physiology population, poor nutrition and sedentary lifestyle often result in low lean muscle mass and poor muscle tone.16,17
Cordina et al21 found that resistance exercise training could improve skeletal muscle mass and maximal oxygen uptake (V˙2max) presumably by the augmentation of lower extremity venous return by muscle pump action in a small group of adult Fontan patients. However, no pediatric study has examined the impact of exercise training on lower extremity skeletal muscle and other peripheral determinants of CRF. The impact of the peripheral musculature on Fontan exercise performance is not completely understood. Greater lower extremity muscle mass decreases venous compliance and increases systemic venous return, stroke volume, and cardiac output in the normal resting circulation.22 Additionally, the peripheral muscle pump augments systemic venous return at the initiation of exercise in upright individuals with normal cardiorespiratory circulation.23 Since the majority of skeletal muscle is in the lower extremities, peripheral muscle mass may be a surrogate for the systemic venous muscle pump. We have previously demonstrated that Fontan patients have lean muscle mass deficits compared with healthy reference patients.17 These skeletal muscle deficits may be critically important to exercise performance in pre-load-dependent Fontan patients who lack a subpulmonary ventricle and depend on passive filling of the systemic ventricle with pulmonary venous return and may be exercise limiting in a subpopulation of Fontan patients. In addition, greater inspiratory strength has been shown to result in greater negative thoracic pressure during exercise, augmenting flow into the Fontan circuit. Preliminary studies of rehabilitation strategies specifically designed to augment these muscle groups suggest that this approach may uniquely benefit the Fontan population. We discuss this approach later in the review.
Despite the limitations of many of these studies, several important conclusions can be drawn from the current literature on this subject. Perhaps most importantly, all these studies have shown an extremely high degree of safety. Even in those studies with a high number of subjects with complex anatomy, the incidence of significant adverse events was extremely low. This appears to be true whether these programs were performed in either an inpatient or outpatient setting. Despite the heterogeneity of most of the study populations, most studies show a modest short-term improvement in at least some of their chosen measures of change in CRF. However, it is clear that long-term adherence and efficiency data are lacking. As such, it is impossible to judge what, if any, long-term benefits may be derived in the congenital heart populations from these programs. These data are going to be essential to develop best practices going forward.
EXERCISE REHABILITATION IN CARDIOMYOPATHIES
Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiomyopathy in children and is characterized by disorganized myocyte muscle bundle arrangement, fibrosis, and asymmetric ventricular hypertrophy.24 Traditionally, expert recommendations have cautioned against participating in vigorous athletics, aiming to avoid tachycardia and decreased diastolic filling time, surging catecholamines, dehydration, or metabolic acidosis, and the accompanying theoretical risk of hemodynamically significant ventricular arrhythmia and sudden cardiac death (SCD).25,26 While low-intensity physical activity is not prohibited, >50% of patients with HCM do not meet minimum physical activity guidelines due to a belief that they are unable to safely exercise, a result which comes with significant detrimental psychological effects27,28 and also has the unintended consequence of increasing the cardiovascular risk profile in a population already with risk factors in place.29,30 In fact, studies have highlighted the importance of CRF in patients with HCM, showing that those with impaired V˙2max had significantly lower rates of survival than those with normal CRF.31
However, the mindset toward exercise, and CR, in patients with HCM is shifting.32 Recent population-based studies have shown that approximately 65% of SCD events in patients with HCM occurred during routine activities including rest or sleep, and that athletes with HCM who have undergone implantable cardioverter defibrillator implantation had similar event rates regardless of whether they participated or refrained from sports,33–35 suggesting that vigorous physical activity may not be the inciting factor for SCD in many patients with HCM.36,37 In fact, in animal models of HCM, exercise has been shown to prevent or even reverse fibrosis and myocyte disarray,38 suggesting that regular exercise training early in the disease course may be an important avenue by which to modify disease progression. Interestingly, athletes with HCM who regularly participate in competitive athletics have decreased maximal left ventricular wall thickness, an increased left ventricular end-diastolic volume, lower incidence of systolic anterior motion of the mitral valve leaflets, less mitral regurgitation, and a lower left ventricular outflow tract gradient compared with sedentary peers.39 While it is unclear whether these findings are a product of their training, or instead a marker of less severe disease, which allows for athletic participation, it does raise the possibility that regular exercise may have a critical therapeutic role in the treatment of patients with HCM.
It is in this setting that a recent study of 20 patients ages 49-75 yr with symptomatic HCM showed that subjects who completed 60 min of moderate-to-vigorous exercise, 2 times/wk in a protocol that gradually increased intensity, had an improvement in CRF without any adverse events.40 On a larger scale, the RESET-HCM trial (Study of Exercise Training in Hypertrophic Cardiomyopathy) randomized 136 adults with a mean age of 50.4 yr and HCM to either their usual activity or a moderate-intensity exercise program. The results showed increased CRF without adverse events including sustained ventricular arrhythmia, sudden cardiac event, appropriate implantable cardioverter defibrillator shock, or death.41 A follow-up study evaluating the safety and efficacy of high-intensity exercise for improving CRF in adults with HCM is ongoing.42 Given that cardiac output in patients with HCM is ultimately limited by stroke volume, other studies have targeted exercise interventions, which specifically aim to improve diastolic filling,43 again emphasizing the potential utility of CR in this population. However, it is unclear how these findings translate to the pediatric and adolescent populations. There are essentially no similar data available for the pediatric population. This may reflect in large part the reluctance of pediatric cardiologists to engage in the shared decision-making process that has been used in the adult population engaged in these activities.
Dilated Cardiomyopathy, Heart Failure, and Ventricular Assist Devices
Children with HF often have significant deconditioning with impaired functional capacity and quality of life.44–47 The use of an inotropic support or ventricular assist device (VAD) to support children with HF either as a bridge to recovery, transplant, or as destination therapy has rapidly increased with significant improvements in survival.48,49 Thus, a focus on optimizing functional capacity, quality of life, and musculoskeletal strength is now being recognized as an important aspect of care in this complex population. CR that incorporates both aerobic exercise and musculoskeletal training aims to improve CRF by decreasing frailty, improving respiratory muscle strength, and increasing musculoskeletal reserve. For children with HF awaiting heart transplantation, optimizing musculoskeletal conditioning and rehabilitation status is an important modifiable risk factor to potentially improve pre-transplant waitlist functional status and potentially post-transplant outcomes by decreasing time to extubation, ambulation, and hospitalization length of stay. CR for dilated cardiomyopathy, advanced HF on inotropic, and VAD support has been shown to be safe both in children and in adults.4,50–52 One study in children with dilated cardiomyopathy demonstrated that participation in CR was associated with improved aerobic capacity based on 6-min walk test distance and decreased waist circumference.50 Recent data from our center have demonstrated that participation in CR in pediatric VAD recipients when using an increased pump speed titration during training is associated with improved CRF.53
In adults with HF receiving either medical therapy or VAD support, participation in CR has been associated with increased aerobic fitness, increased quality of life, decreased mortality, and decreased rehospitalization rates compared with standard care.51,52,54–57 Based on this, guidelines on management of adults with HF and VADs recommend CR as part of standard care.58,59 However, limited data exist regarding standardized recommendations on CR in children. The International Society for Heart and Lung Transplantation guidelines for the management of pediatric HF recommend prescribed individualized exercise training to improve clinical status in ambulatory patients with HF, although this is based on expert consensus as it is level of evidence C.18 Guidelines on pediatric VAD management do not exist to date and, therefore, standardized recommendations for CR in pediatric VAD recipients are lacking. Further study of the benefits of CR for children with HF and VAD support is needed.
Application to Practice
In the current era there exists no specific consensus statements or specific guidelines in the practice of pediatric CR. Therefore, there are limited data on the best approaches to CR in these complex and heterogeneous pediatric populations and most pediatric institutions are relegated to using their own unique experience to provide clinical care. For this reason, we cite data that exist and supplement it with information on the approaches currently used at our institution.
General Considerations for Facility and Staffing
Sufficient space is needed to accommodate a variety of ergometers and resistance equipment, as well as monitoring and emergency resuscitation equipment, while maintaining adequate space to access the patient in emergency situations. Although no specific space requirements have been established for pediatric CR centers, we suggest that a minimum of 250 ft2, with ≥500 ft2 when multiple ergometers and resistance stations are employed.60
In order to accommodate a range of ages and heart disease, pediatric CR gymnasiums should be stocked with a variety of exercise equipment, including treadmills and cycle ergometers modified to fit smaller patients, light hand and leg weights or resistance bands, and floor mats for flexibility and mobility training. Wireless telemetry to monitor heart rate (HR) and rhythm should be available, as should pulse oximetry monitors. In addition to emergency resuscitation equipment, medical gases including wall oxygen should be included. In a setting where the gymnasium is located adjacent to an inpatient unit, a nurse call system should be in place for emergency situations.
Key staff includes at least one physician who is well trained in pediatric exercise medicine who should be present during the CR sessions of any child at increased risk of a complication, such as a child with a life-threatening arrhythmia or VAD. Ideally, two staff members trained in clinical exercise physiology and CHD should be present for all sessions, especially when multiple patients are training at the same time. In situations where the child requires mechanical or respiratory support, nursing staff, respiratory therapists, or perfusionists may be required to provide additional monitoring.
Exercise Training in a Nonclinical Setting and Home-Based Rehabilitation
Pediatric CR programs have been shown to be hampered by the lack of facilities specifically designed for children and access to geographically proximate rehabilitation centers. This has led to preliminary studies assessing the effectiveness of home-based or remote CR strategies.7,15,61–65 Most of these studies incorporate a traditional method of 8-12 wk of home-based exercise intervention with initial and follow-up in-person evaluations. All but a few showed at least some improvement in function, ranging from CRF to increased habitual physical activity. Digital forms of monitoring were also used to assess physical activity remotely. This is particularly attractive in the current pandemic era, where access to facilities may be unavailable. Therefore, the use of remote monitoring should be explored with the hopes of providing monitoring, assessment, and effectiveness of exercise training in larger cohorts of children and adolescents with CHD.
A Single-Center Approach (Children's Hospital of Philadelphia)
We describe the approach of our center as a potential model for CR. Prior to enrollment into the exercise training program, all patients undergo a complete assessment by the CR staff. Initial evaluations performed include measurements of muscle strength, flexibility, vital sign stability, and functional mobility (6-min walk test). Following clearance by the referring physician, measurement of functional exercise performance is obtained, usually by formal cardiopulmonary exercise testing (CPX), to determine parameters needed for exercise programming (ie, HR, work rate, V˙2max, AT, etc). These parameters are primarily used to prescribe the aerobic exercises during the course of the CR program.
Often there are central cardiovascular and peripheral musculoskeletal limitations to aerobic exercise in patients palliated for CHD. The approach at our center aims at both, with goals toward improvements that not only promote acts of daily living, but also provide the tools to continue regular physical activity beyond formal CR sessions in the outpatient setting.
Specific Program Components
Formal evaluation, including CPX studies listed earlier, provides information from which an individualized prescription for intensity can be formulated for the bicycle, treadmill, and other equipment.
- Aerobic exercise. Each patient is asked to perform a single bout of moderate intensity aerobic exercise for 20-30 min based on an exercise prescription derived from the formal exercise study. Measurements of HR, blood pressure, arterial oxygen saturation, rating of perceived exertion, and exertional symptoms are assessed at the midpoint.
- Dynamic strength and flexibility. Strength and flexibility exercises are performed at the beginning or end of the aerobic exercise session. Strengthening exercises include upper and lower body resistance training utilizing handheld dumbbells and ankle cuff weights of varying pounds customized by the exercise prescription for each patient. Resistance training intensity (weight) is aimed at maintaining 60% of pre-training 1-repetition maximal voluntary contraction for each muscle group corresponding to a perceived exertion of 12-13. This method has been described previously by McBride et al.4 Each patient is asked to perform several stretching exercises primarily to improve overall range of motion and secondarily to reduce the risk of injury from exercise.
Congenital Heart Disease Rehabilitation and Exercise Training Program
There are at least four approaches to assessing training intensity: percentage of V˙o2peak, percentage of predicted peak HR, percentage of HR reserve, and rating of perceived exertion. At present, there is no consensus as to which parameter is optimal for measuring training intensity. Using CPX to assess V˙o2peak, and its surrogate, the ventilatory AT, offers the noninvasive evaluation of overall functional capacity and is the recommended method for assessing CRF in patients with cardiac or pulmonary disease.66 However, since access to the needed CPX equipment and personnel is still suboptimal, some clinical programs must use other surrogates to prescribe exercise intensity.67
The rationale for using HR to prescribe exercise intensity is based on the linear relationship between HR and V˙o2. Using HR alone as a basis for the prescription of exercise in children and adolescents with CHD poses complications. The HR response in this group varies considerably, depending on the particular defect, largely as a result of chronotropic impairment that occurs with many congenital cardiac defects. Therefore, using the conventional approach of age-predicted maximal HR may often be inappropriate.
The use of ratings of perceived exertion between 12 and 15 has been reported to strongly correlate with training intensities of 40-80% V˙o2peak in healthy subjects, as well as in congestive HF patients. However, the use of these scales during maximal exercise testing may not translate into the same intensity during exercise training sessions, and children may not be able to reliably use rating of perceived exertion scales.68
As noted in the review of the literature, single-ventricle physiology is unique and there is a growing body of data that suggest a different approach to CR may be needed for this population. We are currently evaluating such an approach. Skeletal muscle mass, especially lower body, may be a modifiable determinant of exercise performance in Fontan patients. Few studies have addressed the physiologic adaptations that result from exercise training in pediatric Fontan patients in order to further understand the relative contributions of central and peripheral factors to exercise tolerance.
Similar to CHD, unfortunately there are very limited data on exercise training programs in pediatric patients with cardiomyopathy or HF.69–72 The expanded use of VADs in the pediatric population has led to a growing population in need of aggressive rehabilitation in anticipation of either transplantation or discharge to a home setting. As noted earlier, there are essentially no data on best approaches to these patients. As with the Fontan patients, we therefore present our current research-driven approach to their management.
When developing CR recommendations for children with dilated cardiomyopathy, HCM, or HF, CPX can provide valuable guidance by assessing for evidence of exercise-induced symptoms, arrhythmia, ischemia, or abnormal hemodynamic response.18 Furthermore, use of submaximal and maximal CPX parameters can provide guidance for target HR during routine exercise training.4,58 Specifically identifying the HR at the AT can provide an individualized target HR for moderate-intensity exercise training. Based on this data, individualized exercise training programs can be developed to be followed either at a CR center or as a home-based training program. The current practice at our institution does not distinguish between HCM and other types of cardiomyopathy in designing exercise rehabilitation programs, using regularly scheduled circuit training to support aerobic fitness.
Regarding children with a VAD in CR, baseline CRF is assessed for development of an individualized exercise training prescription based on baseline maximal CPX using cycle ergometry with a ramp protocol. Initial CPX is performed after VAD implant based on clinical readiness as determined by the primary care team with general guidelines shown in Table 3. Patients then participate in 3 structured CR sessions/wk with focus on musculoskeletal strengthening. Prevention of the Valsalva maneuver is emphasized to prevent interference with VAD flow. Patients are monitored on telemetry during their initial exercise training session only. A follow-up CPX is performed at 6-8 wk after baseline CPX to determine changes in exercise performance following exercise training and rehabilitation
Table 3 -
Readiness Checklist for Cardiac Rehabilitation With Baseline Cardiopulmonary Exercise Testing After Ventricular Assist Devices Implant in Children
|>14 d post-implant
|Able to participate in physical activity required for exercise testing and training
|Off continuous vasoactive infusion
|No active hematologic concerns (bleeding, thrombosis, extreme supratherapeutic INR)
|No active wound infection or poor healing (sternotomy or driveline site)
|No active myocarditis
|No significant arrhythmia burden refractory to medical therapy
Abbreviation: INR, international normalized ratio.
Health Care Coverage
Medicare and most private insurers have historically covered CR services for conditions that are modeled after adult-acquired heart disease such as myocardial infarction or coronary bypass surgery. Pediatric CR reimbursement by payors has steadily gained traction, especially in HF, cardiomyopathy, and complex cyanotic CHD. Our experience at Children's Hospital of Philadelphia is such that after copays are provided by the family, reimbursement from payors can be up to 80% of the direct cost for CR services with the primary aim of avoiding potential readmission to the hospital.
Due to limited data regarding CR in children with heart disease, ongoing research is needed to identify the optimal approach regarding patient selection and exercise training outcomes. To address this issue, our center and others are actively studying various exercise training regimens in children with HCM, HF supported on VAD, and those with Fontan circulations. The goal of these studies is to improve and standardize the delivery of pediatric exercise training and CR through the development of evidence-based guidelines that can be implemented throughout the centers specializing the care of these patients. This will have the ultimate goal of allowing collaborative data use across these sites, facilitating the multicenter approach that will be needed to best address key research questions in this complex population.
Cardiopulmonary rehabilitation in pediatric congenital and acquired heart disease is currently a field in its infancy. For all the reasons noted in this review, the data available are not easily extrapolated to larger populations. In many ways, this is inherent in the nature of the pediatric cardiac population being both smaller and, most importantly, incredibly heterogeneous when compared with adult heart disease. Nonetheless, significant strides have been made in moving the field forward over the last two decades. This is especially true for complex heart disease and those patients with the most impaired function. Current research holds the promise for the development of programs that are practical, scalable, and can be implemented in most clinical sites within the foreseeable future.
The NIH grant paid to the institution.
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