Abstract 17306: Right Ventricular Response to Exercise in Patients with an Obstructed Right Ventricle-to-Pulmonary Artery Conduit: Effects of Transcatheter Pulmonary Valve Replacement

Abstract

Background: In patients with repaired congenital heart disease, the clinical evaluation of right ventricular outflow tract (RVOT) conduit dysfunction (i.e. stenosis or regurgitation) has classically involved analysis of anatomic and physiologic changes of the right ventricle (RV) at rest. Such evaluation does not reflect dynamic changes that occur during exercise, or elicit functional changes in response to physiologic stress. In this study, we characterized the physiologic effects of exercise on the RV in patients with an obstructed RVOT conduit before and after transcatheter pulmonary valve replacement (TPV). Methods: Patients with RVOT conduit obstruction who underwent TPV between March 2010- March 2011 at Children's Hospital Boston were enrolled. Exercise echocardiograms were performed in all patients. Rest and peak exercise RVOT gradient, RV systolic pressure, and 2D global longitudinal RV strain parameters (composite of 6-segment RV strain from a 4-chamber apical view via speckled tracking) were obtained prior to and 6 months post-TPV. Results: A total of 12 patients, of whom 8 had Tetralogy of Fallot (67%) were enrolled and completed the study. Median age at the time of TPV was 18 yrs (range 4 - 28). Prior to TPV, the median resting maximum instantaneous gradient (MIG) was 60mmHg (range 32-85) and increased with peak exercise to 95 mmHg (range 50 -156; p<0.001). At baseline, resting global RV strain was -15% (-6, 19.6) and increased to -17% (-3, -22; p =0.005) at peak exercise. Following TPV, median MIG declined significantly at rest to 21mmHg (range 16-41; p= 0.03 vs. pre-TPV) and at peak exercise, 41mmHg (range 27-81; p=0.03 vs. pre-TPV), but still with a significant increase in MIG from rest to peak exercise (p<0.001). Following TPV, global RV strain increased at rest,-17% (-2, -24; p= 0.005), and further at peak exercise, -20% (-6, -23; p=0.01). Conclusions: Exercise led to a significant increase in the peak RVOT gradient and global longitudinal RV strain both before and after TPV. TPV resulted in significantly improved RVOT gradient and longitudinal RV myocardial deformation both at rest and during peak exercise.