Improvement in left ventricular filling properties after relief of right ventricle to pulmonary artery conduit obstruction: contribution of septal motion and interventricular mechanical delay

Abstract

To investigate the impact of relief of right ventricle (RV) to pulmonary artery (PA) conduit obstruction on septal motion and ventricular interaction and its functional implications for left ventricular (LV) filling properties. In 20 consecutive patients with congenital heart disease and RV to PA conduit obstruction, the following were prospectively assessed before and after percutaneous pulmonary valve implantation (PPVI): the septal curvature and LV volumes throughout the cardiac cycle by magnetic resonance imaging; RV to LV mechanical delay by 2D-echocardiographic strain imaging; and objective exercise capacity. Percutaneous pulmonary valve implantation led to a reduction in RV to LV mechanical delay (127.9 +/- 50.9 vs. 37.7 +/- 35.6 ms; P < 0.001) and less LV septal bowing in early LV diastole (septal curvature: -0.11 +/- 0.11 vs. 0.07 +/- 0.13 cm(-1); P < 0.001). Early LV diastolic filling (first one-third of diastole) increased significantly (17.5 +/- 9.4 to 30.4 +/- 9.4 mL/m(2); P < 0.001). The increase in early LV diastolic filling correlated with the reduction in RV to LV mechanical delay (r = -0.68; P = 0.001) and change in septal curvature (r = 0.71; P < 0.001). In addition, the improvement in peak oxygen uptake (56.0 +/- 16.0 vs. 64.1 +/- 13.7% of predicted; P < 0.001) was associated with the increase in early LV diastolic filling (r = 0.69; P = 0.001). Relief of RV to PA conduit obstruction significantly improves early LV filling properties. This is attributed to more favourable septal motion and reduction in interventricular mechanical delay.