Correlation between defibrillation shock outcome and coherence in electrocardiograms

Area of Science:

• Cardiology
• Biomedical Engineering
• Signal Processing

Background:

• Ventricular fibrillation (VF) cycle periods correlate with reentrant activation patterns.
• ECG signals from different thoracic locations reflect cardiac electrical activity inversely proportional to distance.
• ECG cycle period similarity can indicate spatiotemporal similarity in cardiac activation rates.

Purpose of the Study:

• To investigate if spatiotemporal similarity in ECG cycle periods, measured by coherence, correlates with defibrillation shock outcome.
• To test the hypothesis that increased spatial similarity in cardiac activation rates improves defibrillation success.

Main Methods:

• Time-varying coherence was estimated from orthogonal ECGs during electrically induced VF in dogs.
• An adaptive least mean square algorithm was used to calculate coherencies.
• Coherence was integrated within a frequency region centered at the dominant frequency.

Main Results:

• Coherencies between the sagittal-transverse ECG pair were 10%-15% higher (P < 0.05) in successful defibrillation trials compared to unsuccessful ones.
• Higher coherence values correlated with successful termination of VF.
• Data collected from ten dogs included 206 successful and 221 unsuccessful defibrillation trials.

Conclusions:

• Increased spatiotemporal similarity in cardiac activation rates, indicated by higher ECG coherence, is associated with successful defibrillation.
• These findings support the hypothesis that more uniform cardiac activation enhances defibrillation probability, particularly in regions with low potential gradients during shock.