Related Experiment Video
Updated: Jul 11, 2026

Optocardiography and Electrophysiology Studies of Ex Vivo Langendorff-perfused Hearts
Published on: November 7, 2019
Period-doubling bifurcation to alternans in paced cardiac tissue: crossover from smooth to border-collision
Carolyn M Berger1, Xiaopeng Zhao, David G Schaeffer
1Department of Physics, Duke University, Durham, North Carolina 27708, USA.
Abstract:
We investigate, both experimentally and theoretically, the period-doubling bifurcation to alternans in heart tissue. Previously, this phenomenon has been modeled with either smooth or border-collision dynamics. Using a modification of existing experimental techniques, we find a hybrid behavior: Very close to the bifurcation point, the dynamics is smooth, whereas further away it is border-collision-like. The essence of this behavior is captured by a model that exhibits what we call an unfolded border-collision bifurcation. This new model elucidates that, in an experiment, where only a limited number of data points can be measured, the smooth behavior of the bifurcation can easily be missed.
Related Concept Videos
Dysrhythmias III: Characteristics of Dysrhythmias
Electrophysiology of Normal Cardiac Rhythm
The Cardiac Cycle
The Process
Electrical signals—sent from the sinoatrial (SA) node in the right atrial wall to the atrioventricular (AV) node between the right atrium and right ventricle—cause both atria to simultaneously contract. When the signal reaches the AV node, it pauses for approximately a tenth of a second, allowing the atria to contract and empty blood into the...
Mechanism of Cardiac Arrhythmias
Dysrhythmias IV: Characteristics of Bradyarrhythmias
Cardiac Cycle
During the cardiac cycle, blood flow through the heart is regulated entirely by changing pressure gradients. This sequence of events begins with the heart in a state of total relaxation, known as mid-to-late diastole, during which blood passively flows from...
