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Simulating Initiation and Termination of Reentry in Cardiac Tissue. Ena Xiao Mentor: David M. Chan. GOAL. To understand the dynamic of a ring of excitable media that can be a cause of cardiac arrhythmia. Background. Arrhythmias - abnormal heart rhythms
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Simulating Initiation and Termination of Reentry in Cardiac Tissue Ena Xiao Mentor: David M. Chan
GOAL • To understand the dynamic of a ring of excitable media that can be a cause of cardiac arrhythmia.
Background • Arrhythmias - abnormal heart rhythms • Bradycardia - less than 60 beats per min. • Tachycardia - pace of the heart is faster than the regulatory signal from the sinus node (over 100 beats per min). • Rapid heart beating in the ventricles can be life-threatening. (ex. Ventricular fibrillation - heart can’t pump any blood) Currently, over 2.2 million Americans are living with atrial fibrillation. (Estimated by American Heart Association)
Glossary • Reentry: unidirectional recirculation of AP. • UDC: unidirectional circulation • Diastolic Interval (DI): recovering time between AP. • Conduction Time (CT): the time required for an AP wave front to travel a specified distance. • Action Potential Duration (APD): defined with respect to a threshold voltage. • T1 / T2 / T3 / T4: Threshold
Ring-like Cardiac Tissue • A schematic representation of a ring of cardiac tissue.
Restitution Curve (a) APD Restitution Curve (B) CT Restitution Curve
Thresholds In order to initiate and maintain reentry, the following thresholds must be satisfied. • Each cell requires a minimum DI for recovery of excitability. • The reentrant action potential must propagate around the ring slow enough for cell one to recover excitability • The reentrant action potential must propagate around the ring fast enough to excite cell one before the SA node
What I have done. • Generating data from the model with different parameters, and looking at patterns. • Studying different conditions that may cause lethal arrhythmia.
Thank You! Dr. David Chan, Mentor Dr. Allison Johnson, Coordinator of HHMI Summer Scholar Program Hailan Liu