Effects of transcatheter pulmonary valve replacement on the hemodynamic and ventricular response to exercise in patients with obstructed right ventricle-to-pulmonary artery conduits.

OBJECTIVES

This study sought to investigate the effects of exercise on the right ventricle in patients with an obstructed right ventricular outflow tract (RVOT) conduit before and after transcatheter pulmonary valve replacement (TPVR).

BACKGROUND

Conventionally, assessment of the right ventricle in congenital heart disease patients with dysfunctional RVOT conduits is performed at rest. However, this does not reflect dynamic exercise changes.

METHODS

Exercise stress echocardiography (ESE) before and 6 months after TPVR was performed. ESE protocol included measurement of rest and immediate post-exercise RVOT maximal instantaneous gradients (MIGs), right ventricular (RV) systolic pressure, 2-dimensional fractional area change, and global longitudinal strain (GLS).

RESULTS

Twenty patients with RVOT conduit obstruction (median age, 18 years), the majority (n = 14) with tetralogy of Fallot, completed the study. Pre-TPVR, the median resting MIG across the RVOT was 53 mm Hg (23 to 95 mm Hg) and increased to 93 mm Hg (49 to 156 mm Hg; p < 0.001) with exercise. After TPVR, the median MIG at rest was 26 mm Hg (6 to 41 mm Hg, and after exercise, it was 45 mm Hg (9 to 102 mm Hg), both significantly lower than before TPVR (p ≤ 0.001), but there was still a substantial increase in gradient with exercise in many patients. The RV fractional area change, RV GLS, and left ventricular GLS, both at rest and after exercise, were significantly greater after TPVR than before. A greater pre-TPVR exercise-related increase in RV function was associated with improvement in peak Vo2 after TPVR (p = 0.01).

CONCLUSIONS

In patients with obstructed RVOT conduits, TPVR resulted in significant improvement in conduit stenosis and RV function at both rest and at peak exercise and in exercise cardiopulmonary function. The ability to augment RV function at peak exercise before TPVR was associated with improved exercise capacity 6 months after TPVR.