Exercise Stress Echocardiographic Assessment of Outflow Tract and Ventricular Function in Patients With an Obstructed Right Ventricular-to-Pulmonary Artery Conduit After Repair of Conotruncal Heart Defects

Abstract

This study assessed right ventricular (RV) and RV outflow tract (RVOT) function and pressure in response to exercise in patients with an obstructed RV-pulmonary artery (PA) conduit using exercise stress echocardiography (ESE) to evaluate these parameters. RV-PA conduits inevitably develop stenosis and/or regurgitation over time. Assessment of conduit obstruction only at rest may not reveal the extent of physiologic perturbation related to RV pressure loading. Patients with a stenotic RV-PA conduit who were being considered for transcatheter pulmonary valve placement were approached prospectively. ESE was performed and ventricular images were obtained at rest and at peak exercise. Forty patients (median age 17 years) were enrolled. Most patients had tetralogy of Fallot (63%) and were in New York Heart Association class II (59%). Exercise stress echocardiographic images were adequate in 38 patients (95%). With exercise there was a significant increase in maximum instantaneous RVOT gradient from rest (59 vs 96 mm Hg, p <0.001); exercise-induced change in RVOT gradient correlated with global RV strain at rest (r = -0.3, p = 0.05). Compared to measurements at rest there were significant increases in median peak longitudinal strain of the left ventricular free wall, interventricular septum, and global left ventricular strain at peak exercise. There were no significant changes in median RV strain at peak exercise (RV free wall -14.3 [-26, -8] at rest vs -15.2 [-27, -3] at peak exercise, p = 0.87; global RV strain -13.9 [-32, -9] vs -15.1 [-23, -6], p = 0.11). In conclusion, using ESE it was possible to evaluate abnormal ventricular function and conduit dysfunction at peak exercise in patients with an obstructed RV-PA conduit.