Endocardial activation during ventricular fibrillation in normal and failing canine hearts

Area of Science:

• Cardiology
• Electrophysiology
• Heart Failure Research

Background:

• Congestive heart failure (CHF) is known to promote ventricular fibrillation (VF), a life-threatening arrhythmia.
• Understanding the electrophysiological mechanisms underlying VF in CHF is crucial for developing effective treatments.

Purpose of the Study:

• To compare the characteristics of ventricular fibrillation (VF) in dogs with induced congestive heart failure (CHF) versus normal dogs.
• To investigate the impact of CHF on the spatial and temporal dynamics of VF.

Main Methods:

• Induction of CHF in dogs via myocardial infarction and rapid ventricular pacing.
• Utilized a noncontact, multielectrode array catheter for real-time left ventricular (LV) endocardial electrograms.
• Employed Fast Fourier Transform (FFT) analysis to assess VF frequency characteristics and wavefront dynamics.

Main Results:

• No significant difference was found in the peak or centroid frequency of VF between CHF and normal dogs.
• The average number of simultaneous noncontiguous wavefronts during VF was significantly lower in CHF dogs compared to normal dogs.
• Wavefront turnover rate did not differ between groups and remained stable over time.

Conclusions:

• The fundamental frequency characteristics of ventricular fibrillation (VF) are not altered by congestive heart failure (CHF).
• Dilated and abnormal ventricles in CHF sustain fewer active wavefronts during VF compared to normal ventricles.
• These findings suggest altered spatial dynamics of VF in CHF, despite unchanged frequency.