Differences between left and right ventricular chamber geometry affect cardiac vulnerability to electric shocks

Area of Science:

• Cardiovascular Physiology
• Computational Biology
• Biophysics

Background:

• Cardiac vulnerability to electric shocks is well-studied regarding strength and waveform.
• The role of ventricular anatomy in shock-induced electrical polarization and propagation remains unquantified due to limitations in 3-D electrical activity mapping.

Purpose of the Study:

• To investigate the influence of structural differences between left and right ventricles on vulnerability to electric shocks.
• To quantify the contribution of ventricular anatomy to shock outcome using optical imaging and 3-D simulations.

Main Methods:

• Utilized optical imaging experiments and 3-D bidomain simulations in rabbit hearts.
• Applied uniform-field, truncated-exponential, monophasic shocks of reversed polarity at various coupling intervals.
• Mapped 3-D electrical activity to analyze shock-induced polarization and postshock propagation.

Main Results:

• Reversing shock polarity (RV- vs. LV- shocks) altered the vulnerability area shape.
• RV- shocks showed minimal dependence of arrhythmogenesis on coupling interval, while LV- shocks exhibited higher arrhythmia induction probability with longer coupling intervals.
• 3-D simulations revealed that shock polarity reversal relocates the main postshock excitable area from the LV wall to the septum, with septal effects being state-dependent.

Conclusions:

• Ventricular anatomy, specifically the location of the main postshock excitable area within the 3-D ventricular volume, significantly influences cardiac vulnerability and shock outcome.
• Understanding these anatomical contributions is crucial for improving defibrillation efficacy.