Simulation study of cellular electric properties in heart failure

Area of Science:

• Cardiovascular Physiology
• Computational Biology
• Electrophysiology

Background:

• Severe heart failure significantly elevates the risk of sudden cardiac death, primarily due to ventricular tachyarrhythmias.
• Cellular electrophysiological alterations in heart failure, such as afterdepolarizations, are implicated in the genesis of ventricular arrhythmias.

Purpose of the Study:

• To develop a mathematical model of the human ventricular action potential incorporating key ionic currents to investigate cellular electrophysiological changes in heart failure.
• To elucidate the mechanisms underlying action potential alterations and their pro-arrhythmic potential in failing cardiomyocytes.

Main Methods:

• Incorporation of selected human ionic current data into a ventricular action potential model, utilizing the Luo-Rudy model for uncharacterized currents.
• Simulation of action potentials in failing and non-failing ventricular myocytes to analyze electrophysiological consequences.

Main Results:

• Action potential duration is prolonged in failing ventricular myocytes due to enhanced Na+-Ca2+ exchange, slowed [Ca2+]i transient decay, and reduced K+ and Na+-K+ pump currents.
• Inhibition of the rapid delayed rectifier K+ current (I(Kr)) specifically promotes early afterdepolarizations in failing myocytes.
• Spontaneous Ca2+ release from the sarcoplasmic reticulum triggers premature action potentials exclusively in failing myocytes.

Conclusions:

• The developed model highlights critical ionic mechanisms, including altered Na+-Ca2+ exchange and K+ currents, contributing to electrical instability in heart failure.
• The model identifies I(Kr) inhibition and spontaneous Ca2+ release as significant triggers for arrhythmias in failing hearts.
• This computational model serves as a valuable tool for exploring therapeutic strategies targeting myocardial electrical excitability in heart failure.