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Mechanical Control of Relaxation Using Intact Cardiac Trabeculae
Published on: February 17, 2023
Effect of nonuniform muscle contraction on sustainability and frequency of triggered arrhythmias in rat cardiac
Masahito Miura1, Taichi Nishio, Taiki Hattori
1Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, Japan. mmiura@med.tohoku.ac.jp
Circulation
|June 16, 2010
Summary
Cardiac muscle nonuniformity drives sustained, lethal arrhythmias by causing calcium surges. This study reveals how altered contraction patterns influence arrhythmia frequency and sustainability, crucial for understanding heart disease.
Area of Science:
- Cardiovascular Physiology
- Cardiac Electrophysiology
- Arrhythmogenesis
Background:
- Arrhythmias can be benign or lethal, influenced by their sustainability and frequency.
- Diseased hearts often exhibit nonuniform muscle contraction, a factor implicated in lethal arrhythmias.
Purpose of the Study:
- To investigate the effect of cardiac muscle nonuniformity on the sustainability and frequency of triggered arrhythmias.
- To understand the mechanisms underlying lethal arrhythmias in diseased hearts.
Main Methods:
- Measured force, membrane potential, and intracellular calcium concentration ([Ca(2+)](i)) in rat ventricular trabeculae.
- Induced nonuniform contraction using 2,3-butanedione monoxime (BDM) or blebbistatin.
- Studied the impact of muscle stretch and calcium sensitizers on sustained arrhythmias.
Main Results:
- Sustained arrhythmias were inducible only with muscle nonuniformity induced by BDM or blebbistatin.
- Calcium surges preceded synchronous [Ca(2+)](i) increases during sustained arrhythmias.
- Muscle lengthening/shortening modulated arrhythmia cycle length, and Ca(2+) sensitizers accelerated arrhythmias.
Conclusions:
- Cardiac muscle nonuniformity is a key determinant of triggered arrhythmia sustainability and frequency.
- Calcium surges dissociated from myofilaments play a critical role in arrhythmia generation.
- Findings provide insights into the mechanisms of lethal arrhythmias in non-uniformly contracting cardiac muscle.
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