Figure 1.

Pressure–volume loops and STE parameters. (A–C) Typical pressure–volume loops were recorded from one animal under baseline conditions (left) and during infusion of esmolol (middle) and dobutamine (right). The E_max was calculated as the linear slope of end-systolic points from multiple loops obtained during IVC occlusion. E_max decreased with esmolol and increased with dobutamine. Two-dimensional STE was performed simultaneously and STE parameters were determined off line. (D–F) left ventricular twist is decreased from baseline with esmolol and increased with dobutamine.