Differential Response of the Right and Left Ventricle to β-Adrenergic Stimulation: An Echo Planar MR Study in Intact Animals

PURPOSE: The purpose of this study was to compare the response in contractility of the right (RV) and left (LV) ventricle of the heart to beta-adrenergic stimulation using an echo planar MR technique. METHOD: In six sheep, RV and LV pressure-volume (P-V) relationships were constructed simultaneously using intraventricular pressures and volumes measured with echo planar MRI at rest and during dobutamine stress. Contractility changes were quantified by assessment of the end-systolic P-V relationship (ESPVR) and the preload recruitable stroke work (PRSW). RESULTS: Both the ESPVR the the PRSW showed a significant increase in contractility for both ventricles after dobutamine administration. The increase in contractility was significantly larger for the LV than for the RV, both measured wit the ESPVR (p < 0.0003) and the PRSW (p < 0.007). CONCLUSION: This study shows the usefulness of echo planar MRI to assess myocardial contractility of both ventricles simultaneously. Furthermore, the study shows that beta-adrenergic stimulation has a significantly greater positive inotropic effect on LV contractility than on RV contractility.