Fig. 1.

Study population and design.

Experimental protocols for assessment of cardiac and other responses to (A) acute β-adrenoceptor stimulation with DOB, (B) sustained β-adrenoceptor stimulation with ISO and (C) acute β-adrenoceptor stimulation with DOB following sustained β-adrenoceptor stimulation with ISO. (D) For echocardiographic analyses, 2-dimensional (B-Mode) images were recorded in parasternal long- (left panel) and short-axis (right panel) projections with guided one-dimensional M-mode recordings at the mid-ventricular level, apical of the posteriomedial papillary muscle in both views. Standard measurements of inter-ventricular septum (IVS), left ventricular internal diameter (LVID) and left ventricular posterior wall (LVPW) were performed in systole and diastole in parasternal long-axis projection. Left ventricular (LV) cavity size and wall thickness were measured during at least three beats from this projection and averaged. Left ventricular anterior wall (LVAW) thickness was determined during at least three beats in systole and diastole in short-axis projection.