Restrictive right ventricle and regional right ventricular function in patients with corrected Tetralogy of Fallot

Background: Tetralogy of Fallot (TOF) encompasses hypertrophy of the right ventricle (RV) which can impair diastolic filling. After surgical correction, restrictive RV physiology may persist, leading to a prolonged postoperative course but possibly better exercise tolerance later in life. Late diastolic pulmonary artery forward flow (LDPAFF) is used for determining the presence or absence of RV restriction with different cut-offs, although this is a continuous parameter.

Methods: 105 patients with surgically corrected TOF (median age 7.9 [1.6 - 44.8] years) had standardized echocardiography in the setting of two Competence Network Congenital Heart Defects multicenter studies. 2D, Doppler, and tissue Doppler values were measured centrally, including RV regional myocardial velocity, strain rate, and strain. Pearson correlation coefficients and t-test using a cut-off of 0.3 m/s for LDPAFF were calculated.

Results: LDPAFF velocity correlated positively with RV outflow tract diameter (p<0.05), RV ejection fraction (p<0.01), systolic pulmonary artery velocity (p<0.01), and negatively with basal RV systolic strain rate and strain (p<0.01). Patients with LDPAFF ≥ 0.3 m/s were older (13.3 vs. 8.8 years; p<0.05), had higher RV ejection fraction (46 vs. 37%; p<0.05) and higher systolic pulmonary artery velocities (2.1 vs. 1.7 m/s; p<0.05).

Conclusions: A higher degree of RV restriction as determined by the magnitude of LDPAFF is found in TOF patients with more residual pulmonary artery stenosis, larger RV outflow tracts and lower RV systolic regional strain and strain rate. A cut-off of 0.3 m/s shows systolic and diastolic functional differences between TOF groups.