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Spectro-temporal mapping of the surface electrocardiogram in clinically normal dogs
C A Calvert1, L I Kushner, G J Jacobs
1Department of Small Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
American Journal of Veterinary Research
|March 1, 1997
Summary
Sedation aids signal-averaged ECG procedures in dogs without altering results. Optimal analysis uses 40-50 millisecond segments of the terminal QRS complex for identifying dogs at risk of sudden cardiac death.
Area of Science:
- Veterinary Cardiology
- Electrophysiology
- Signal Processing
Background:
- Signal-averaged electrocardiography (SAECG) is a non-invasive technique to detect low-amplitude signals.
- Ventricular late potentials (VLPs) on SAECG are associated with increased risk of sudden cardiac death.
- Optimizing SAECG acquisition and analysis is crucial for accurate VLP detection.
Purpose of the Study:
- To establish normative data for SAECG variables in healthy dogs.
- To determine the effect of sedation on SAECG parameters, specifically terminal QRS complex segment lengths.
- To identify optimal window settings for VLP detection in canine SAECG.
Main Methods:
- Signal-averaged ECGs were recorded from healthy dogs using subdermal electrodes and standard leads.
- Frequency-domain analysis via Fast Fourier Transform (FFT) was applied to QRS complex and ST segment.
- Correlation ratios were calculated using spectro-temporal mapping with varying segment lengths (30-50 ms) and QRS durations (10-20 ms).
Main Results:
- Sedation reduced noise and heart rate but did not significantly impact SAECG results.
- Correlation ratios were consistent across 30, 40, and 50 ms segments.
- Lower correlation ratios were observed when including 20 ms versus 10 ms of the terminal QRS complex.
Conclusions:
- Sedation is a safe and effective method to facilitate SAECG acquisition in dogs.
- Analysis of 40-50 ms segments, starting 10 ms before the QRS end, reliably yields correlation ratios >67%.
- Spectro-temporal mapping may aid in identifying canine patients at risk for sudden cardiac death due to VLPs.