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Updated: Oct 7, 2025
Dual-Dye Optical Mapping of Hearts from RyR2R2474S Knock-In Mice of Catecholaminergic Polymorphic Ventricular Tachycardia
Published on: December 22, 2023
The Purkinje-myocardial junction is the anatomic origin of ventricular arrhythmia in CPVT
Daniel J Blackwell1, Michela Faggioni1, Matthew J Wleklinski1,2
1Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
Abstract:
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an arrhythmia syndrome caused by gene mutations that render RYR2 Ca release channels hyperactive, provoking spontaneous Ca release and delayed afterdepolarizations (DADs). What remains unknown is the cellular source of ventricular arrhythmia triggered by DADs: Purkinje cells in the conduction system or ventricular cardiomyocytes in the working myocardium. To answer this question, we used a genetic approach in mice to knock out cardiac calsequestrin either in Purkinje cells or in ventricular cardiomyocytes. Total loss of calsequestrin in the heart causes a severe CPVT phenotype in mice and humans. We found that loss of calsequestrin only in ventricular myocytes produced a full-blown CPVT phenotype, whereas mice with loss of calsequestrin only in Purkinje cells were comparable to WT mice. Subendocardial chemical ablation or restoration of calsequestrin expression in subendocardial cardiomyocytes neighboring Purkinje cells was sufficient to protect against catecholamine-induced arrhythmias. In silico modeling demonstrated that DADs in ventricular myocardium can trigger full action potentials in the Purkinje fiber, but not vice versa. Hence, ectopic beats in CPVT are likely generated at the Purkinje-myocardial junction via a heretofore unrecognized tissue mechanism, whereby DADs in the ventricular myocardium trigger full action potentials in adjacent Purkinje cells.
Insights
Catecholaminergic polymorphic ventricular tachycardia (CPVT) originates from ventricular myocytes, not Purkinje cells. Loss of calsequestrin in ventricular cells triggers CPVT, while Purkinje cell loss does not.
Area of Science:
- Cardiovascular Research
- Molecular Cardiology
- Cardiac Electrophysiology
Background:
- Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a life-threatening arrhythmia linked to RYR2 mutations causing hyperactive calcium release.
- The precise cellular origin of CPVT-triggered ventricular arrhythmias—Purkinje cells or ventricular cardiomyocytes—remains unclear.
Purpose of the Study:
- To determine the cellular source of ventricular arrhythmias in CPVT.
- To investigate the role of cardiac calsequestrin in CPVT pathogenesis.
Main Methods:
- Genetic manipulation in mice to selectively knock out cardiac calsequestrin in Purkinje cells or ventricular cardiomyocytes.
- Assessment of CPVT phenotype following catecholamine challenge.
- In silico modeling of cardiac action potential propagation.
Main Results:
- Selective loss of calsequestrin in ventricular myocytes recapitulated the full CPVT phenotype.
- Loss of calsequestrin solely in Purkinje cells did not induce arrhythmias.
- Subendocardial cardiomyocyte intervention protected against catecholamine-induced arrhythmias.
- In silico models indicated ventricular DADs can trigger Purkinje action potentials, but not vice versa.
Conclusions:
- Ventricular cardiomyocytes, not Purkinje cells, are the primary source of CPVT arrhythmias.
- Delayed afterdepolarizations in ventricular myocardium trigger arrhythmias at the Purkinje-myocardial junction.
- Cardiac calsequestrin is crucial for preventing CPVT by regulating myocyte calcium handling.
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