Event

Bioengineering Seminar Series: Richard Gray

Friday, September 24, 2010
11:00 a.m.-12:00 p.m.
Room 2108, Chemical and Nuclear Engineering Bldg.
Professor Sameer Shah
sameer@umd.edu

An Engineering Approach to the Study of Cardiac Fibrillation and Defibrillation

Richard Gray
Senior Biomedical Engineer
Center for Devices and Radiological Health
U.S. Food and Drug Administration

Normally the human heart beats once per second and each contraction is triggered by a synchronized, rapidly propagating electrical wave. Premature beats elicited by disease or other abnormal events such as electrocution can lead to the formation of life-threatening irregular heart beats (i.e., arrhythmias), including ventricular fibrillation (VF). VF is the leading cause of death in the United States, killing well over 1,000 individuals each day. The only effective way to terminate fibrillation is using high-energy electric fields to “defibrillate” the heart. The spatio-temporal patterns of transmembrane potential (Vm) responsible for these phenomena remained unknown until recently. As a postdoc Dr. Gray (working with Jose Jalife) pioneered the technique of fluorescence video imaging of Vm over the entire heart surface which elucidated these patterns. This talk will include the presentation of the first high-resolution images of Vm recordings from isolated rabbit and pig hearts using CCD cameras and fluorescence dyes during normal, pacing, arrhythmias, and defibrillation. Dr. Gray showed for the first time, that VF was not a random phenomena, but involves multiple unstable propagating electrical impulses in the form of rotating “spiral” waves. The fact that complex patterns of electrical wave propagation underlie VF may explain the failure of anti-arrhythmic drugs and preclude clinical gene therapy. The long-term objective of Dr. Gray’s research is to elucidate the mechanisms of cardiac fibrillation and defibrillation using a highly-integrated experimental and theoretical approach with the hope that an improved quantitative understanding of basic mechanisms will lead to novel clinical therapies. The talk will provide an overview of over a decade of Dr. Gray’s highly interdisciplinary engineering approach to analyze the complex spatio-temporal patterns in the heart using the theory of non-linear dynamics. This approach includes the application of a variety of theoretical and mathematical tools including state-space dynamics, non-linear waves, the Doppler effect, feedback control, and phase resetting.

Audience: Graduate  Faculty  Post-Docs