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The effects of direct current countershock on ventricular late potentials
Pacing and Clinical Electrophysiology : PACE
|March 1, 1987
Summary
Direct current shock (DC shock) minimally impacts ventricular late potentials, which are crucial for assessing antiarrhythmic drug efficacy. Post-shock recordings are recommended for accurate drug effect analysis in electrophysiology studies.
Area of Science:
- Cardiology
- Electrophysiology
- Signal Processing
Background:
- Ventricular late potentials (VLPs) are recorded using signal-averaged electrocardiograms (SAEKGs).
- VLPs are associated with sustained ventricular tachycardia and may indicate antiarrhythmic drug efficacy.
- Acute drug testing in electrophysiology labs often follows direct current countershock (DC shock).
Purpose of the Study:
- To evaluate the impact of DC shock on VLPs.
- To determine if DC shock influences VLP characteristics used for antiarrhythmic drug efficacy assessment.
Main Methods:
- SAEKGs were recorded before and after 13 DC shocks administered for cardioversion.
- Analysis focused on QRS duration, high-frequency filtered QRS duration, and high-frequency signal amplitude under 40 microvolts.
- Root mean square amplitudes in the terminal 40 milliseconds were also assessed.
Main Results:
- No significant changes were observed in QRS duration or high-frequency filtered QRS duration.
- A minor, clinically insignificant increase in terminal 40 ms root mean square amplitude was noted (41 to 49 microV).
- VLPs did not consistently appear or disappear after electrical cardioversion.
Conclusions:
- DC shock has minimal effect on VLPs, making them a reliable marker post-shock.
- Comparisons of VLP changes after antiarrhythmic drug administration should utilize post-DC shock SAEKGs.
- This finding is crucial for accurate interpretation of drug efficacy in electrophysiology studies requiring cardioversion.