Echocardiographic assessment of right ventricular volumes after surgical repair of tetralogy of Fallot: clinical validation of a new echocardiographic method

Background: Assessment of right ventricular (RV) volumes and function is important in patients after tetralogy of Fallot (TOF) repair. Currently, cardiac magnetic resonance imaging (MRI) is considered the clinical reference method for RV volume and function measurements. Three-dimensional (3D) knowledge-based reconstruction derived from two-dimensional echocardiographic imaging with magnetic tracking is a novel approach to RV volumetrics. The aim of this study was to assess the feasibility and reliability of this novel echocardiographic technique in patients after TOF repair. The accuracy of the method was assessed by comparison with measurements obtained by cardiac MRI.

Methods: Thirty patients (mean age, 13.7 ± 2.8 years) after TOF repair, referred for cardiac MRI, were included. Immediately after MRI, echocardiographic image acquisition was performed using a standard ultrasound scanner linked to a Ventripoint Medical Systems unit. Echocardiographic and MRI measurements were performed offline. Parameters analyzed were end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction. Intraobserver, interobserver, and intertechnique variability was assessed using Pearson's correlation analysis, coefficients of variation, and Bland-Altman analysis.

Results: Echocardiographic two-dimensionally based 3D reconstruction was highly feasible, with low intraobserver and interobserver variability for EDV and slightly higher variability for ESV and ejection fraction. The 3D reconstruction values for EDV, ESV, and ejection fraction were correlated highly with MRI values, with low coefficients of variation. The agreement between both methods was high. Three-dimensional reconstruction slightly underestimated RV volumes, by 2.5% for EDV and 4.6% for ESV compared with MRI volumes.

Conclusions: In patients after TOF repair, echocardiographic 3D reconstruction is highly feasible, with good reproducibility for measurements of RV EDV. There is good agreement with MRI measurements, with a small underestimation of RV volumes. The use of this method in clinical practice warrants further investigation.