Effects of alterations in left ventricular filling, contractility, and systemic vascular resistance on the ascending aortic blood velocity waveform of normal subjects

Healthy volunteers, awake, rested, supine subjects

Increasing infusion rates of dobutamine (1.25 to 5 micrograms/kg.min), esmolol (1.25 to 5 mg/min), phentolamine (1.25 to 5 mg/min), methoxamine (1.25 to 5 mg/min), metaraminol (1.25 to 5 mg/min), and increasing plasma removal (0.5 to 1 L)

Placebo (1.25 to 5 mL of 0.9% saline/min)

Ascending aortic blood flow velocity waveform variables (stroke distance, minute distance, peak velocity, mean acceleration, flow time corrected for heart rate, index of systemic vascular resistance)surrogate