Echocardiography as a Simple Initial Tool to Assess Right Ventricular Dimensions in Patients with Repaired Tetralogy of Fallot before Undergoing Pulmonary Valve Replacement: Comparison with Cardiovascular Magnetic Resonance Imaging

OBJECTIVE: Accurate assessment of the right ventricle (RV) is essential in patients with repaired tetralogy of Fallot (TOF). We proposed a simple echocardiographic method to assess the RV dimensions and evaluated the relationship between linear echocardiographic measures of the RV and RV volumes obtained by cardiovascular magnetic resonance imaging (CMR). METHODS: A total of 45 patients (27.4 ± 11.2 years; 40% male) with repaired TOF underwent CMR and echocardiography. Using echocardiography, RV dimensions were assessed from the parasternal short-axis view using the longest RV internal diameter perpendicular to the mid-interventricular septum. Significant RV dilatation was defined as an RV end-diastolic volume index >160 mL/m(2) on CMR. RESULTS: There were significant correlations between RV dimensions determined by echocardiography and the pulmonary regurgitation fraction, RV size, and function determined by CMR. The cutoff values of echocardiographic RV outflow tract (RVOT), end-systolic and end-diastolic dimension indices, and the combination of RVOT and end-diastolic dimension indices to determine significant RV dilatation were 19.0, 19.4, 24.5, and 45.2 mm/m(2) , respectively. The positive and negative predictive values for significant RV dilatation were 89.7% and 68.8% with RVOT diameter index ≥19.0 mm/m(2) , 85.0% and 52.4% with RV end-systolic dimension index ≥19.4 mm/m(2) , 87.5% and 64.7% with RV end-diastolic dimension index ≥24.5 mm/m(2) , and 92.3% and 80.0% with the combination of RVOT and end-diastolic dimension indices ≥45.2 mm/m(2) , respectively. CONCLUSION: Echocardiography can be used to assess RV size in patients with repaired TOF with acceptable correlations with CMR as the reference standard.