Assessing ST Segment Changes and Ischemia During Exercise Stress Testing in Patients with Hypoplastic Left Heart Syndrome and Fontan Palliation

Retrograde Flow to Aortic Root Predicts Inferior Cardiopulmonary Performance and Restrictive Lung Physiology in Fontan Circulation

Background

Cardiac output in Fontan circulation depends on systemic venous pressure, pulmonary vascular resistance, and ventricular function. Because myocardial function is dependent on coronary perfusion, we studied whether retrograde flow to aortic root in the mitral/aortic atresia subgroup of hypoplastic left heart syndrome (HLHS) affects cardiopulmonary performance.

Methods

We studied 26 stable Fontan patients (14.4 ± 2.4 years) with right (RV, n = 17) and left (LV, n = 9) systemic ventricle morphology. All RV patients had HLHS and were subdivided according to postnatal flow to the hypoplastic ascending aorta being antegrade (HLHS-A) or retrograde (HLHS-R) due to valve atresia. Physical activity was assessed by questionnaire (LASERI, a questionnaire for Finnish children regarding physical activity), cardiopulmonary exercise test (1-minute ramp protocol), body composition (Biacorpus RX 4000), and muscle fitness (EUROFIT). These data were correlated with the postnatal aorta size and current branch pulmonary artery size index (McGoon index).

Results

Patients with HLHS-R seldom self-reported engagement in vigorous physical activity and had significantly lower cardiopulmonary performance (peak oxygen uptake [VO2peak]) than patients with LV morphology (P = 0.037), but not compared with patients with HLHS-A. Branch pulmonary artery size did not correlate with VO2peak. Patients with HLHS-R had most severe lung restrictions (forced vital capacity z-score -3 ± 0.9, P = 0.0073; forced expiratory volume in 1 second z-score -3.3 ± 1.1, P = 0.001).

Conclusions

Young Fontan patients with LV had better cardiopulmonary performance than patients with HLHS. Patients with HLHS-R were the least active and had the lowest VO2peak and most restrictive lungs. It is important to recognize postnatally single ventricle patients at high risk for inactivity to promote an active and healthy lifestyle.

Brazilian Guideline for Exercise Testing in Children and Adolescents - 2024

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The Effects of Exercise Training on Cardiopulmonary Exercise Testing and Cardiac Biomarkers in Adult Patients with Hypoplastic Left Heart Syndrome and Fontan Circulation

Background: Several studies have shown that adult patients with Hypoplastic Left Heart Syndrome (HLHS) and Fontan circulation have a reduced exercise tolerance that affects daily life. Recent studies have investigated the effects of aerobic exercise training in patients with univentricular heart; however, this research topic is still poorly studied. The aim of this study was to evaluate the effects of an aerobic exercise training program on cardiopulmonary exercise testing parameters and cardiac biomarkers in patients with HLHS. Methods: We enrolled 12 patients with a mean age of 24 ± 2.5 years (range 22−27 years), 50% male, with HLHS at Bambino Gesù Children’s Hospital IRCCS. All patients underwent a cardiopulmonary test and blood sampling before (T0) and after (T1) a 4-week aerobic exercise program. Cardiac biomarkers hs-cTnT, NT-proBNP, ST2, GDF-15 were studied. Results: Data analysis demonstrated an increase in cardiorespiratory performance after 4 weeks of aerobic exercise training activity. In particular, the data showed a significant improvement in test duration (p < 0.05), heart rate at rest (p < 0.05), heart rate recovery 1 min (p < 0.05), VO2 max (p < 0.01) and oxygen uptake efficiency slope (p < 0.05). At the same time, the data showed a significant reduction in NT-proBNP and ST2 values (p < 0.01 and p < 0.05, respectively) and a significant increase in GDF-15 (p < 0.01). No significant changes were found between the hs-cTnT values. Conclusions: Our study demonstrated the 4-week efficacy of an aerobic training program in improving cardiorespiratory performance and cardiac biomarker values in adult patients with HLHS and Fontan circulation. More studies with larger numbers of patients will be needed to confirm these data.

Exercising with a Single Ventricle: Limitations and Therapies

Treatment for Hypoplastic Left Heart Syndrome (HLHS) and other single ventricle conditions requires a series of surgical interventions for long-term survival, typically culminating in the Fontan procedure. The result is an abnormal circulatory physiology with an absence of a sub-pulmonary ventricle. Exercise capacity in the Fontan circulation is often limited and is due to multiple factors, both central and peripheral. Multiple interventions, both pharmacologic and nonpharmacologic, have been studied to attempt to overcome these inherent limitations. This review will focus on the physiology of the exercising Fontan patient and on the interventions aimed at the enhancement of exercise capacity studied thus far.

Cardiac rehabilitation in the paediatric Fontan population: development of a home-based high-intensity interval training programme

INTRODUCTION

We evaluated the safety and feasibility of high-intensity interval training via a novel telemedicine ergometer (MedBIKE™) in children with Fontan physiology.

METHODS

The MedBIKE™ is a custom telemedicine ergometer, incorporating a video game platform and live feed of patient video/audio, electrocardiography, pulse oximetry, and power output, for remote medical supervision and modulation of work. There were three study phases: (I) exercise workload comparison between the MedBIKE™ and a standard cardiopulmonary exercise ergometer in 10 healthy adults. (II) In-hospital safety, feasibility, and user experience (via questionnaire) assessment of a MedBIKE™ high-intensity interval training protocol in children with Fontan physiology. (III) Eight-week home-based high-intensity interval trial programme in two participants with Fontan physiology.

RESULTS

There was good agreement in oxygen consumption during graded exercise at matched work rates between the cardiopulmonary exercise ergometer and MedBIKE™ (1.1 ± 0.5 L/minute versus 1.1 ± 0.5 L/minute, p = 0.44). Ten youth with Fontan physiology (11.5 ± 1.8 years old) completed a MedBIKE™ high-intensity interval training session with no adverse events. The participants found the MedBIKE™ to be enjoyable and easy to navigate. In two participants, the 8-week home-based protocol was tolerated well with completion of 23/24 (96%) and 24/24 (100%) of sessions, respectively, and no adverse events across the 47 sessions in total.

CONCLUSION

The MedBIKE™ resulted in similar physiological responses as compared to a cardiopulmonary exercise test ergometer and the high-intensity interval training protocol was safe, feasible, and enjoyable in youth with Fontan physiology. A randomised-controlled trial of a home-based high-intensity interval training exercise intervention using the MedBIKE™ will next be undertaken.