Effects of Esmolol Infusion on Hemodynamic Responses to Isometric Handgrip

Summary

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Description

This study will test the hypothesis that infusion of Esmolol, a fast-acting ?1 selective antagonist, will acutely improve oxygen (O2) supply to the heart during small muscle mass exercise in adults with and without peripheral artery disease (PAD). ?1 selective antagonists (or "?1 blockers") are used...

This study will test the hypothesis that infusion of Esmolol, a fast-acting ?1 selective antagonist, will acutely improve oxygen (O2) supply to the heart during small muscle mass exercise in adults with and without peripheral artery disease (PAD). ?1 selective antagonists (or "?1 blockers") are used to lower heart rate and improve O2 supply-to-demand balance in patients with coronary artery disease. It was recently reported that coronary exercise hyperemia (in response to fatiguing handgrip or plantar flexion exercise) is attenuated in patients with PAD. Preliminary data further show that in healthy young subjects, Esmolol infusion lessens the rise in the rate pressure product (an index of myocardial O2 demand) during handgrip exercise without negatively affecting coronary artery blood velocity. The current project will evaluate how Esmolol infusion affects coronary blood velocity (an index of coronary blood flow) and myocardial demand at rest, during handgrip exercise, and during post-exercise cuff occlusion in 1) young healthy adults, 2) older healthy adults and 3) older adults with PAD. Understanding how beta-1 selective blockade influences coronary and systemic vascular function may aid in the development of therapies to reduce myocardial ischemia in this population, which is a population at heightened coronary event risk both at rest and during blood pressure-raising tasks.

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