Control of Complex Behavior in Cardiac Muscle
Abstract
The goal of this research program is to develop experimental methods for suppressing complex behavior in small pieces of cardiac muscle and attempt to generalize these methods to spatio-temporal disorganization in hearts during fibrillation. The general approach is to investigate methods developed by the nonlinear dynamics community for controlling complex behavior using small perturbations. This problem is of broad interest to physicists because the heart is a physical realization of a nonlinear system displaying complex spatio-temporal dynamics. I explore the dynamics of cardiac muscle using an animal model testbed consisting of small pieces of periodically paced bullfrog. Understanding the behavior of small pieces of tissue is important for developing methods for controlling the observed behaviors as well as complex spatio-temporal dynamics observed in whole hearts. In this testbed I find alternans and bistability are common. Using this testbed, I demonstrate experimentally feedback control of alternans, a behavior that is believed to be responsible for the genesis of fibrillation in whole hearts. To suppress alternans I use Time Delay Auto-Synchronization, a feedback scheme that compares the current behavior of the system to a previous one and adjusts a parameter to minimize the difference. I also demonstrate control with a restricted version of this protocol that only allows shortening of the pacing intervals. I also use this simple testbed to demonstrate experimentally that it is possible to induce transitions between bistable dynamical states by injecting a single stimulus between paces.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1999
- Accession Number
- ADA599426
Entities
People
- George M. Hall
Organizations
- Duke University