Clinical Investigation
Right Ventricular Performance in Complex Congenital Heart Disease
Quantification of Right Ventricular Electromechanical Dyssynchrony in Relation to Right Ventricular Function and Clinical Outcomes in Children with Repaired Tetralogy of Fallot

https://doi.org/10.1016/j.echo.2018.03.012Get rights and content

Highlights

  • Electromechanical dyssynchrony is common after TOF repair.

  • RV dyssynchrony is quantifiable by echocardiography.

  • Electromechanical dyssynchrony parameters are associated with RV dysfunction.

  • RV lateral-septal delay and prestretch amplitude are associated with RV remodeling.

  • Electromechanical dyssynchrony is associated with exercise capacity and arrhythmia.

Background

Electromechanical dyssynchrony occurs ubiquitously following tetralogy of Fallot (TOF) repair, manifesting electrically as a wide QRS duration and mechanically as a right-sided septal/apical flash. Early septal activation and prestretch of the right ventricular (RV) basal lateral wall followed by its postsystolic shortening contributes to inefficient RV mechanics. However, a right-sided septal flash is a dichotomous finding, and the severity of RV dyssynchrony as a continuous spectrum in relationship to RV dysfunction and clinical outcomes in patients with repaired TOF has not been studied. The aim of this study was to quantify the severity of electromechanical dyssynchrony in relation to RV remodeling and clinical outcomes in a pediatric cohort following TOF repair.

Methods

A retrospective analysis was performed in 81 children with RV volume loading after TOF repair, aged 13.6 ± 2.9 years, and compared with 50 matched control subjects.

Results

Patients had higher RV basal-lateral prestretch and postsystolic strain amplitude and duration, RV mechanical dispersion, and basal lateral-septal wall delay compared with control subjects (P < .001 for all). All intra-RV dyssynchrony timing parameters were associated with reduced cardiac magnetic resonance–derived RV ejection fraction and/or echocardiography–derived RV longitudinal strain. Prestretch duration as a percentage of total shortening time and RV basal lateral–to–midseptal delay were independently associated with RV dysfunction. Postsystolic strain amplitude was higher in patients with ventricular arrhythmias compared with arrhythmia-free patients (7.8% [4.2%–13%] vs 2.0% [0%–12.5%], P = .03).

Conclusion

RV prestretch duration, postsystolic strain, and RV lateral-septal delay quantify RV electromechanical dyssynchrony severity and reflect the underlying pathophysiology. The prestretch duration percentage and RV basal lateral–to–midseptal delay were independently associated with RV dysfunction, potentially providing a clinical tool to quantify RV electromechanical dyssynchrony.

Section snippets

Study Population

We performed a retrospective cross-sectional analysis of echocardiograms between January 2007 and December 2014 at our institution, with approval from the institutional research ethics board. A departmental echocardiography database was used to screen for eligible patients following TOF repair who had sequential echocardiographic and CMR studies. Patients who had a primary diagnosis of an atrioventricular septal defect with TOF or more than minor residual intracardiac shunts were excluded.

Demographics

Of 100 consecutive patients with repaired TOF, 18 were excluded for RVOT gradients > 40 mm Hg, and one was excluded because of poor quality imaging. Consequently, 81 patients with TOF and 50 control subjects were included in the final analysis (Figure 3). The diagnosis was TOF in 71 patients (88%); double-outlet right ventricle, TOF type, in four (5%); pulmonary atresia with TOF in four (5%); and TOF with absent pulmonary valve syndrome in two (2.5%). The median age of complete repair was

Discussion

RV mechanical dyssynchrony is ubiquitous in patients with TOF but has not been systematically quantified, and its association with RV function and clinical parameters as a continuous parameter has not been explored. We sought to describe dyssynchrony severity and its relationship to pathophysiology, RV function, and clinical outcomes in patients with repaired TOF through inefficient stretch and strain, intra-RV mechanical dispersion, and delay, reflecting the underlying pathophysiology. We and

Conclusion

The severity of RV electromechanical dyssynchrony can be quantified by RV basal-lateral prestretch, PSS, RV lateral-septal delays, and mechanical dispersion, which are associated with RV remodeling and dysfunction. In practice, RV basal-lateral prestretch amplitude is simple to measure and correlates with parameters of RV dysfunction, providing a practical approach to assessing RV electromechanical dyssynchrony severity that reflects the underlying pathophysiology. Quantification of RV

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  • Cited by (0)

    Conflicts of Interest: None.

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