Changes in Cardiac Deformation Following Physiologic Alterations and Inotropic Support.

"Data is collected at baseline as two controls.~Three physiological interventions follows, and data is collected after each:~Increasing heart rate in two steps by atrial pacing through a temporary pacemaker.~Raising cardiac preload by increasing central venous pressure through leg elevation.~Raising cardiac afterload by increasing systemic vascular resistance through administering of phenylephrine.~Baseline is restored, and data is collected before drug adminstration as two controls, then after a first (half) dose, and finally after a second (full) dose."

"Data is collected at baseline as two controls.~Three physiological interventions follows, and data is collected after each:~Increasing heart rate in two steps by atrial pacing through a temporary pacemaker.~Raising cardiac preload by increasing central venous pressure through leg elevation.~Raising cardiac afterload by increasing systemic vascular resistance through administering of phenylephrine.~Baseline is restored, and data is collected before drug adminstration as two controls, then after a first (half) dose, and finally after a second (full) dose."