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Local activation variability during monomorphic ventricular tachycardia in the dog
D S Rosenbaum1, D J Wilber, J M Smith
1Cardiac Unit, Massachusetts General Hospital, Harvard Medical School, Boston 02114.
Cardiovascular Research
|March 1, 1992
Summary
Beat to beat variability in local activation time is common during ventricular tachycardia (VT). These alternans-type oscillations may be intrinsic to re-entry mechanisms in VT.
Area of Science:
- Cardiovascular Physiology
- Cardiac Electrophysiology
Background:
- Sustained monomorphic ventricular tachycardia (VT) is a life-threatening arrhythmia.
- Understanding the electrophysiological mechanisms underlying VT is crucial for developing effective therapies.
Purpose of the Study:
- To investigate beat-to-beat variability in local activation time during sustained monomorphic VT.
- To explore the potential role of re-entry mechanisms in VT.
Main Methods:
- Developed a digital template matching algorithm to analyze local activation time variability.
- Mapped ventricular activation in a canine model of myocardial infarction during induced VT, ventricular pacing, and sinus rhythm.
Main Results:
- Significant beat-to-beat variability in local activation time (mean 3.2 ms) was observed during VT, compared to ventricular pacing (0.2 ms) and sinus rhythm (0.7 ms).
- Alternans-type oscillations in local activation time occurred during 70% of VT episodes, independent of electrogram morphology alternans.
Conclusions:
- Beat-to-beat variability and alternans-type oscillations in local activation time are prevalent during sustained monomorphic VT.
- These findings suggest that such variability may be an intrinsic property of re-entry circuits driving VT.