Ventricular fibrillation and atrial fibrillation are two different beasts

Area of Science:

• Cardiovascular Physiology
• Computational Biology
• Biophysics

Background:

• Cardiac fibrillation, including ventricular fibrillation (VF) and atrial fibrillation (AF), is a complex phenomenon.
• The role of cardiac tissue geometry in wave propagation dynamics during fibrillation is not fully understood.
• Existing models often simplify the three-dimensional nature of cardiac chambers.

Purpose of the Study:

• To explore the influence of cardiac chamber geometry on the mechanisms of ventricular fibrillation (VF) and atrial fibrillation (AF).
• To differentiate the underlying mechanisms sustaining VF and AF based on anatomical differences.

Main Methods:

• Theoretical analysis of wave propagation in three-dimensional cardiac tissue models.
• Consideration of rotational anisotropy in ventricular muscle fiber orientation.
• Examination of the impact of pectinate muscle network geometry in the atria.

Main Results:

• Thick ventricular walls facilitate transmural reentry, potentially leading to VF through 3D wave dynamics.
• Complex atrial geometry, particularly pectinate muscles, may destabilize reentry via long-distance electrical connections, causing AF.
• Distinct geometric factors likely underlie the mechanisms sustaining VF and AF.

Conclusions:

• Cardiac geometry is a critical factor in the initiation and maintenance of cardiac fibrillation.
• Ventricular fibrillation (VF) mechanisms are influenced by transmural reentry in thick ventricles.
• Atrial fibrillation (AF) mechanisms are distinct, potentially driven by the intricate geometry of the atria and associated muscle structures.