Constant DI pacing suppresses cardiac alternans formation in numerical cable models

Area of Science:

• Cardiovascular Physiology
• Computational Biology
• Cardiac Electrophysiology

Background:

• Cardiac repolarization alternans, characterized by alternating action potential duration (APD), can lead to life-threatening arrhythmias, especially in the ventricles.
• Previous attempts at controlling alternans using chaos theory were limited in spatial extent.
• Pacing with a constant diastolic interval (DI) was previously shown to suppress alternans in single-cell models by disrupting feedback mechanisms.

Purpose of the Study:

• To investigate the efficacy of constant DI pacing in controlling cardiac alternans and conduction blocks in larger ventricular cable models.
• To determine the spatial extent and conditions under which constant DI pacing can prevent alternans and wavebreaks.

Main Methods:

• Utilized human ventricular cable models up to 5 cm in length.
• Applied constant DI pacing protocols to simulate wave propagation conditions.
• Compared the effects of constant DI pacing with traditional constant cycle length pacing.

Main Results:

• Constant DI pacing significantly delayed the onset of cardiac alternans and conduction blocks to higher pacing rates compared to constant cycle length pacing.
• This pacing strategy reduced the occurrence of spatially discordant alternans, a precursor to wavebreaks.
• The protective effect of constant DI pacing was enhanced with increased electrotonic coupling along the cardiac fiber.

Conclusions:

• Constant DI pacing demonstrates significant potential for controlling cardiac alternans and preventing arrhythmias.
• This approach offers a promising strategy for improving pacemaker protocols and reducing the risk of life-threatening cardiac events.
• Further experimental validation is warranted to confirm these computational findings.