Related Experiment Videos
Activation sequence of ventricular tachycardia: endocardial and epicardial mapping studies in the human ventricle
L Harris1, E Downar, L Mickleborough
1Department of Medicine, Women's College Hospital, Toronto, Ontario, Canada.
Insights
This study mapped ventricular tachycardia activation sequences in ischemic heart disease patients. Endocardial activation typically preceded epicardial activation, influencing the surface electrocardiogram.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Surgery
Background:
- Ischemic heart disease frequently causes ventricular arrhythmias.
- Understanding ventricular tachycardia (VT) activation patterns is crucial for effective treatment.
Purpose of the Study:
- To investigate intraoperative ventricular tachycardia activation mapping in patients undergoing coronary artery bypass surgery.
- To characterize endocardial and epicardial activation sequences during VT.
Main Methods:
- Simultaneous endocardial and epicardial mapping using a 110-electrode array and an endocardial balloon catheter in 35 patients.
- Recording 61 episodes of ventricular tachycardia during coronary artery bypass grafting.
- Analyzing activation sequences for monoregional, biregional, figure eight, and circular patterns.
Main Results:
- Monoregional spread was the most common activation sequence on both endocardium and epicardium.
- Endocardial activation preceded epicardial activation in over 90% of VT episodes.
- Epicardial activation was a key determinant of the surface electrocardiographic pattern.
Conclusions:
- Ventricular tachycardia activation patterns exhibit diverse configurations.
- Endocardial activation initiates VT and influences epicardial spread.
- Epicardial mapping provides critical insights into VT mechanisms and surface ECG correlation.
Abstract:
Thirty-five patients with ischemic heart disease and ventricular arrhythmias underwent intraoperative activation mapping at the time of coronary artery bypass surgery. During ventricular tachycardia, the sequence of activation in the intact ventricle was recorded simultaneously from 110 endocardial or 110 epicardial sites, or both. A balloon array of electrodes, inserted across the mitral valve, was used to obtain endocardial recordings in the left ventricle, and this appeared to facilitate the induction of ventricular tachycardia. Of 61 episodes of tachycardia, 16 (15 patients) were recorded with the epicardial sock and 45 (20 patients) with the additional use of the endocardial balloon. The sequence of activation during tachycardia was observed to conform to one of four configurations: monoregional spread was the most common activation sequence recorded on both the endocardium and epicardium, while biregional activation and figure eight sequences were recorded exclusively on the epicardium and endocardium, respectively. The fourth sequence was a circular spread of activation observed on both surfaces. Continuous activation throughout the tachycardia cycle length was an infrequent finding. Simultaneous recordings of endocardial and epicardial activation were obtained in 45% of episodes. The sequence of activation recorded on one surface was matched by a similar sequence on the remaining surface in less than half of these. The onset of endocardial activation preceded that of the epicardium in greater than 90% of tachycardia episodes, and the duration of left ventricular endocardial excitation often exceeded that recorded epicardially over both ventricles. The epicardium, however, did appear to be an important determinant of surface electrocardiographic configuration.