Echocardiographic Follow-Up of Right Ventricular Function After Tetralogy of Fallot Operation

Abstract

Aim: Although limited in assessing right ventricular (RV) function, echocardiography is widely used after correction for tetralogy of Fallot (TOF). The change in echocardiographic measurements of RV in asymptomatic patients after TOF repair over a long follow-up time is not explored yet. The variation in simple echocardiographic measurements during follow-up of our TOF patients are presented. The predictive value of those parameters in determining a future pulmonary valve replacement is sought. Method: Asymptomatic patients surviving the first year after correction for simple TOF from February 2007 to December 2019 at Başkent University, Istanbul Hospital are enrolled. Patients are followed annually with echocardiography including: RV area, volume, length, RV outflow tract (RVOT) diameter and gradient, tricuspid annulus diameter, tricuspid lateral annular tissue velocities, tricuspid annular plane systolic excursion, TEI index RV ejection fraction (EF) measurements. The change in the consecutive echocardiographic measurements during follow-up is analysed. Patients are evaluated with a cardiac magnetic resonance (CMR) imaging when deemed necessary and compared with echocardiographic measurements. Results: A total of 66 patients (54.5% males) are operated at age 14.4±9.3 months (78.8% with transannular patch). Twelve patients had pulmonary valve replacement (PVR) operation at an age 10.1±3.1 years. During follow-up of 7.2±4.3 years, tricuspid annulus diameter, RV area, RV inlet length, RV volume, RV volume index significantly increased (p=0.001 for all), whereas RV inlet length index, TEI and TEI z score decreased (p<0.0001 for all). When means are compared, tricuspid annulus (28.8mm vs 25.0mm; p=0.013), RV volume (72.2ml vs 52.2ml; p=0.042), RV inlet length index (77.9mm/m2 vs 60.2mm/m2 ; p=0.013), RVOT diameter (28.7 vs 23.0; p=0.007) are increased. RV EF is decreased (51.3% vs 60.5%; p=0.011) in those requiring PVR. Those with higher RV area index, RV volume index, tricuspid annulus diameter and tricuspid annular z score in their first echocardiography after the TOF repair, are more likely to have a PVR operation later on (p<0.05 for all). RV volume index ≥39ml/m2 predicts a PVR within 7 years with 100% sensitivity and 74% specificity. Tricuspid annular z score less than -0.43 seems to eliminate the possibility of having a PVR within 7 years with a sensitivity of 44% and specificity of 100%. Conclusion: Observing the sequential change in echocardiographic parameters like RV volume index, RV area index, tricuspid annulus z score is reliable in determining right ventricular function and can limit the costly CMR applications. Cut off values of RV volume index >39ml/m2 and tricuspid annulus z score ≥ - 0.43 after the initial TOF repair may determine patients with higher possibility of having early PVR and indicate a closer follow-up.