Effect of constant-DI pacing on single cell pacing dynamics.

Area of Science:

• Cardiology
• Computational Biology
• Biophysics

Background:

• Cardiac alternans, characterized by beat-to-beat variations in action potential duration, precede life-threatening arrhythmias like ventricular fibrillation.
• Previous studies indicated that constant diastolic interval (DI) pacing can suppress voltage-driven alternans.

Purpose of the Study:

• To investigate the impact of constant-DI pacing on cardiac cell dynamics.
• To explore the interaction between constant-DI pacing and the intracellular calcium cycle.
• To determine the influence of voltage-calcium (V-Ca) coupling on these dynamics.

Main Methods:

• Utilized a single-cell numerical model of cardiac action potential.
• Analyzed cardiac cell dynamics near the bifurcation point using a hybrid pacing protocol (constant basic cycle length [BCL] and constant-DI pacing).

Main Results:

• Identified a region of bistability (RB) where constant-DI pacing prevented alternans after switching to constant-BCL pacing.
• Observed that the size of the RB was positively correlated with the strength of V-Ca coupling.
• Found that weaker V-Ca coupling diminished the size of the RB.

Conclusions:

• Constant-DI pacing can induce lasting changes in cardiac cell dynamics, particularly in cells with strong V-Ca coupling.
• This phenomenon suggests potential therapeutic applications for constant-DI pacing in managing cardiac arrhythmias.