Effects of hemodynamic alterations on wall motion in the canine right ventricle

Regional right ventricular (RV) wall motion was analyzed in six closed-chest, anesthetized, paced dogs by measuring distances between chronically implanted radiopaque markers on RV free wall and septum. Normally, contraction started in the sinus region 25 ms before conus region. Highest velocities of shortening occurred in the conus region (2.42 +/- 0.33 lengths/s) and in septum-to-free-wall direction (2.56 +/- 0.40 l/s). Percent shortening for all regions was between 12% and 17%. The data indicate that the RV ejects blood by a uniform reduction in its free wall surface area and septal-to-free-wall distance. Reduced venous return decreased end-diastolic length, percent shortening, maximum velocity of shortening, and time to end-systolic length. RV pressure overload increased end-diastolic length and decreased percent shortening and maximum velocity of shortening. LV pressure overload led to a nonhomogeneous contraction pattern. Percent shortening and maximum velocity of shortening increased in sinal and conal transverse directions and decreased in sinal and conal longitudinal directions; these changes indicate a mechanical interaction between RV and LV.