Arrhythmia Mechanism and Dynamics in a Humanized Mouse Model of Inherited Cardiomyopathy Caused by Phospholamban...

Area of Science:

• Cardiology
• Molecular Biology
• Electrophysiology

Background:

• The Arginine (Arg) 14 deletion (R14del) in phospholamban (hPLN) causes inherited cardiomyopathy.
• The mechanisms behind the early arrhythmogenic phenotype and sudden death in carriers are unclear.

Purpose of the Study:

• To investigate the electrophysiological remodeling caused by the hPLN^R14del mutation.
• To understand the mechanisms underlying the arrhythmogenic phenotype in early-stage cardiomyopathy.

Main Methods:

• High spatiotemporal resolution optical mapping of intact hearts from knock-in mice.
• Comparison between wildtype (PLN^WT) and heterozygous hPLN^R14del mutant mice.
• Ex vivo challenge with isoproterenol and rapid pacing.

Main Results:

• hPLN^R14del hearts showed increased arrhythmia susceptibility without significant structural changes.
• Preferential right ventricular action potential prolongation occurred, unresponsive to beta-adrenergic stimulation.
• A repolarization gradient facilitated conduction block and macroreentrant circuits, leading to ventricular tachycardia (VT) and stable rotors.

Conclusions:

• The hPLN^R14del mutation causes primary electrical remodeling.
• These electrical changes create a substrate for adrenergic-mediated VT in early cardiomyopathy stages.