Commentary based on Sabati AA, Chesney B, Montchal J, Bhat DP. Early experience using implanted hemodynamic monitor (CardioMEMs) for hemodynamic assessment during exercise in pediatric patients with Fontan circulation. Cardiovascular Science 2025;2:[ePub ahead of print].¹; Labrandero C, Deiros L, Abelleira C, Arreo V, Balbacid EJ, Gutiérrez-Larraya F. Hemodynamic monitoring of pediatric patients with heart failure and pulmonary hypertension using CardioMEMS. J Soc Cardiovasc Angiogr Interv 2024;3:[ePub ahead of print].²

Study Questions

What is the safety and utility of invasive implanted hemodynamic monitoring (IHM) using the CardioMEMS™ HF System (Abbott Laboratories, Abbott Park, Illinois) in pediatric patients with heart failure (HF) and pulmonary hypertension (PH)? And what is the safety and utility during cardiopulmonary exercise testing (CPET) in pediatric patients with Fontan circulation (FC)?

Methods

The results of two single-center case series describing the use of IHM in pediatric patients have been recently published (Figure 1; Table 1). The first is the only published report to date describing the use of IHM in pediatric patients with FC during CPET.¹ The second is the first description of using IHM in pediatric patients with PH, including the youngest patient report of IHM placement.²

Figure 1: Expanding the Use of Invasive Implanted Hemodynamic Monitoring in Pediatric Patients: Exercise Hemodynamics, Pulmonary Hypertension, and Heart Failure

Table 1: Summary of Two Single-Center Case Series Describing the Use of IHM in Pediatric Patients

Results

The first case series included four patients with FC (age 9-16 years; three with hypoplastic left heart syndrome and one with hypoplastic right heart syndrome) who underwent CPET with assessment of hemodynamic changes on IHM.¹ The technical aspects of using IHM for exercise in patients with FC are described, starting with supine measurements of IHM pressures, then upright on the cycle ergometer, then during exercise. All patients had an increase in mean pulmonary artery (PA) pressure with exercise, although one patient's mean PA pressure notably increased to 40 mm Hg at peak exercise with systemic desaturation (85% at rest, 71% with exercise) in the presence of a fenestrated FC. This patient was started on a phosphodiesterase-5 inhibitor and, 6 months later, underwent repeat CPET, showing improved exercise performance, less desaturation (96% at rest, 87% with exercise), and improved peak exercise mean PA pressure 15 mm Hg.

The second case series describes the use of IHM in eight pediatric patients (age 2-14 years; weight range 11.5-55 kg), of which six had PH due to various causes (including idiopathic, congenital diaphragmatic hernia, bronchopulmonary dysplasia, mitral valve stenosis, and Eisenmenger syndrome) and two had HF (one with FC, the other with left ventricular systolic dysfunction and aortic stenosis requiring ventricular assist device [VAD] support on a Berlin Heart VAD [Berlin Heart Inc., The Woodlands, Texas]).² Techniques for IHM placement were described and, of the eight IHM devices, seven were placed by femoral venous access and one by jugular venous access. The investigators describe the use of IHM to titrate pulmonary vasodilator therapy without repeat cardiac catheterizations and to intensify diuretic regimens in patients with HF.

Whereas no device-related complications were reported in either study, the one patient with FC in the second case seriesunderwent heart transplant, and the IHM device would not function post-transplant.

Conclusions

These two-case series describe expanded uses for IHM in pediatric patients to evaluate exercise hemodynamics and use of IHM to titrate pulmonary vasodilator therapy with PH and HF management, including use with a VAD.

Perspective

There has been recent attention to the use of IHM in patients with congenital heart disease (CHD),^3,4 and these two studies add to the growing body of literature on use of IHM in pediatric patients.

Sabati et al. built on their center's previous reports of IHM in pediatric patients with FC by reporting use during CPET.^1,5 Although the use of IHM with exercise in patients with CHD has previously been reported,^3,4,6 this is the first study to use IHM with exercise in pediatric patients with FC. Exercise hemodynamics are prognostic in patients with FC⁷; however, they require invasive central venous access during exercise, which pediatric patients may not tolerate. As reported by Sabati et al., and previously by Bradley et al. in adults with FC, the use of IHM allows measurement of PA pressures with exercise without central venous access.^1,6 Larger prospective studies of IHM combined with CPET are needed to help advance the field of exercise hemodynamic assessment in pediatric patients with FC, and should be conducted by experienced teams to understand the fluctuation in IHM readings in a nonpulsatile FC.

Trials of pulmonary vasodilators in patients with FC have not shown significant benefit⁸; however, these trials did not use hemodynamics to optimize patient selection. Although only a single case, this report by Sabati et al. of a patient with significant elevation of PA pressures with exercise that improved with pulmonary vasodilator therapy could be an example of the phenotype of a patient with FC who may benefit from this therapy. Thus, the use of IHM with CPET may help further clarify the role of pulmonary vasodilators in this patient population.

The use of IHM in adult patients with VAD and CHD have been reported previously^3,4; however, the series from Labrandero et al.includes the first pediatric patient supported on a Berlin Heart VAD.² In addition, it also includes the youngest patient for whom IHM has been used (2 years of age; 11.5 kg) and the largest report of IHM use for PH in pediatric patients. IHM use for PH in adults with pulmonary arterial hypertension is an area of growing interest, including in randomized controlled trials of pulmonary vasodilators.⁹ IHM has also been used for monitoring of PH in patients with complex CHD for whom repeat cardiac catheterizations are technically challenging.⁴ This series from Labrandero et al. is the first to use IHM in pediatric patients with PH from a wide range of causes, showing clinical utility and providing hemodynamic data without repeat catheterizations.

There were limitations to both of these studies. Although neither study included any complications from device placement, caution should be taken given the small sample size. Given the potential for complications described in adult studies,⁴ IHM placement in pediatric patients and those with complex CHD should be performed by experienced pediatric interventionalists. Furthermore, whereas IHM can measure PA pressures, it does not measure cardiac output or pulmonary vascular resistance, which are used in common risk scores for PH¹⁰; thus, there is still a role for cardiac catheterization for patients with PH.

In summary, although further studies are needed to add to the safety and efficacy of IHM in pediatric patients, these two studies are examples showing the potential for similar benefit in adult patients with HF, CHD, and PH.

References

1. Sabati AA, Chesney B, Montchal J, Bhat DP. Early experience using implanted hemodynamic monitor (CardioMEMs) for hemodynamic assessment during exercise in pediatric patients with Fontan circulation. Cardiovascular Science 2025;2:[ePub ahead of print].
2. Labrandero C, Deiros L, Abelleira C, Arreo V, Balbacid EJ, Gutiérrez-Larraya F. Hemodynamic monitoring of pediatric patients with heart failure and pulmonary hypertension using CardioMEMS. J Soc Cardiovasc Angiogr Interv 2024;3:[ePub ahead of print].
3. Piccinelli E, Grutter G, Pilati M, et al. Use of the CardioMEMS device in children and patients with congenital heart disease: a literature review. J Clin Med 2024;13:4234.
4. Marshall V WH, Wright LK, Lampert BC, Salavitabar A, Daniels CJ, Rajpal S. Invasive implanted hemodynamic monitoring in patients with complex congenital heart disease: state-of-the-art review. Am J Cardiol 2024;223:123-31.
5. Bhat DP, Graziano JN, Garn BJ, Franklin WJ. Safety and utility of CardioMEMS device for remote pulmonary artery monitoring in paediatric Fontan patients: a case series. Eur Heart J Case Rep 2023;7:[ePub ahead of print].
6. Bradley EA, Jassal A, Moore-Clingenpeel M, Abraham WT, Berman D, Daniels CJ. Ambulatory Fontan pressure monitoring: results from the implantable hemodynamic monitor Fontan feasibility cohort (IHM-FFC). Int J Cardiol 2019;284:22-7.
7. Miranda WR, Jain CC, Borlaug BA, et al. Exercise capacity, NT-proBNP, and exercise hemodynamics in adults post-Fontan. J Am Coll Cardiol 2023;81:1590-600.
8. Kosmidis D, Arvanitaki A, Farmakis IT, et al. Pulmonary vasodilators and exercise in Fontan circulation: a systematic review and meta-analysis. Heart 2024;110:552-9.
9. Varian F, Dick J, Battersby C, et al. Pulmonary hypertension: intensification and personalization of combination Rx (PHoenix): a phase IV randomized trial for the evaluation of dose‐response and clinical efficacy of riociguat and selexipag using implanted technologies. Pulm Circ 2024;14:[ePub ahead of print].
10. Humbert M, Kovacs G, Hoeper MM, et al.; ESC/ERS Scientific Document Group. 2022 ESC/ERS guidelines for the diagnosis and treatment of pulmonary hypertension. Eur Heart J 2022;43:3618-731.