Clinical Investigations
Congenital Heart Disease
Longitudinal Changes in Ventricular Mechanics in Adolescents After the Fontan Operation

https://doi.org/10.1016/j.echo.2023.04.021Get rights and content

Highlights

  • •

    Myocardial deformation parameters decline in adolescents post-Fontan.

  • •

    Reduced torsion in adolescents with Fontan is due to decreased apical rotation.

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    Lower torsion is associated with a higher degree of myocardial fibrosis on CMR.

  • •

    Reduced exercise capacity post-Fontan is associated with lower torsion.

  • •

    Torsional mechanics may be an important parameter to monitor post-Fontan palliation.

Background

Ventricular dysfunction is a significant clinical challenge in the long-term follow-up of patients with single-ventricle (SV) physiology. Ventricular function and myocardial mechanics can be studied using speckle-tracking echocardiography, which provides information on myocardial deformation. Limited information is available on serial changes in SV myocardial mechanics after the Fontan operation. The aim of this study was to describe serial changes in myocardial mechanics in children after the Fontan operation and the relationship of these changes with myocardial fibrosis markers as obtained by cardiac magnetic resonance and exercise performance parameters.

Methods

The authors hypothesized that ventricular mechanics decline in patients with SVs over time and are associated with increased myocardial fibrosis and reduced exercise performance. A single-center retrospective cohort study including adolescents after the Fontan operation was conducted. Ventricular strain and torsion were assessed using speckle-tracking echocardiography. Cardiac magnetic resonance and cardiopulmonary exercise testing data closest to the latest echocardiographic examinations were performed. The most recent follow-up echocardiographic and cardiac magnetic resonance data were compared with those from sex- and age-matched control subjects and with individual patients’ early post-Fontan data.

Results

Fifty patients with SVs (31 left ventricle, 13 right ventricle [RV], and six codominant) were included. Median time at follow-up echocardiography from the time of Fontan was 12.8 years (interquartile range [IQR], 10.6 to 16.6 years). Compared with early post-Fontan echocardiography, follow-up assessment showed reduced global longitudinal strain (−17.5% [IQR, −14.5% to −19.5%] vs −19.8% [IQR, −16.0% to −21.7%], P = .01], circumferential strain (−15.7% [IQR, −11.4% to −18.7%] vs −18.9% [IQR, −15.2% to −25.0%], P = .009), and torsion (1.28°/cm [IQR, 0.51°/cm to 1.74°/cm] vs 1.72°/cm [IQR, 0.92°/cm to 2.34°/cm], P = .02), with decreased apical rotation but no significant change in basal rotation. Single RVs had lower torsion compared with single left ventricles (1.04°/cm [IQR, 0.12°/cm to 2.20°/cm] vs 1.25°/cm [IQR, 0.25°/cm to 2.51°/cm], P = .01). T1 values were higher in patients with SV compared with control subjects (1,009 ± 36 vs 958 ± 40 msec, P = .004) and in those with single RVs compared with single left ventricles (1,023 ± 19 vs 1,006 ± 17 msec, P = .02). T1 was correlated with circumferential strain (r = 0.59, P = .04) and inversely correlated with O2 saturation (r = −0.67, P < .001) and torsion (r = −0.71, P = .02). Peak oxygen consumption was correlated with torsion (r = 0.52, P = .001) and untwist rates (r = 0.23, P = .03).

Conclusions

After the Fontan procedures, there is a progressive decrease in myocardial deformation parameters. The progressive decrease in SV torsion is related to a decrease in apical rotation, which is more pronounced in single RVs. Decreased torsion is associated with increased markers of myocardial fibrosis and lower maximal exercise capacity. Torsional mechanics may be an important parameter to monitor after Fontan palliation, but further prognostic information is required.

Section snippets

Methods

This was a retrospective, longitudinal, single-center cohort study. The study protocol was approved by the institutional research ethics board.

Patient Characteristics

Of the 61 patients with SVs who were included in our initial univentricular myocardial mechanics study,10 11 patients were excluded. Four patients died, one patient received a heart transplant, one received a permanent pacemaker, and five were lost to follow-up at our institution. Of the remaining 50 patients with SVs, 74% were men, with a median age of 15.1 years (IQR, 12.7-17.5 years) at the most recent follow-up. The interval between the first full echocardiographic post-Fontan assessment

Discussion

Using speckle-tracking echocardiography, we present longitudinal data on ventricular strain, torsion, and untwisting in patients with SVs. Our main findings are as follows:

  • 1.

    Ventricular strain and torsion decrease over time in children after Fontan completion.

  • 2.

    Reduced torsion is due to decreased apical rotation and is associated with markers of myocardial fibrosis on CMR as indicated by native T1 values.

  • 3.

    Reduced ventricular torsion and untwisting are associated with impaired exercise performance

Conclusion

After Fontan palliation, there is a progressive decrease in myocardial deformation parameters. The progressive decrease in SV torsion is related to changes in apical rotation, which are more pronounced in single RV morphology and are associated with markers of myocardial fibrosis and exercise capacity. This indicates that torsional mechanics may be an important parameter to monitor after Fontan palliation.

Review Statement

Given his role as JASE Associate Editor, Mark K. Friedberg, MD, PhD, had no involvement in the peer review of this article and has no access to information regarding its peer review. Full responsibility for the editorial process for this article was delegated to Benjamin W. Eidem, MD.

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    • Cited by (0)

    Conflicts of Interest: None.

    Benjamin W. Eidem, MD, served as guest editor for this report.

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    2023 by the American Society of Echocardiography.