Forty-three patients with sustained ventricular tachycardia (VT) caused by prior myocardial infarction underwent intraoperative endocardial activation mapping during a total of 122 episodes of VT. Electrograms obtained during mapping were analyzed to determine the prevalence of local conduction failure during VT (defined as a portion of the local electrogram that did not repeat with every tachycardia cycle). Local conduction failure during VT was observed in 37 (86%) patients and 73 (65%) tachycardias. VT in which local conduction failure was observed were faster than VTs without local conduction failure (cycle length 315 vs 345 msec; p < .05). Local conduction failure occurred most frequently at or near sites having the earliest recorded electrical activity during VT ('site of origin'). Twenty-three patients also had sinus rhythm endocardial mapping at the time of surgery. Areas with abnormal or fractionated electrograms in sinus rhythm (16% vs 8%; p < .01). Although the mechanism responsible for local conduction failure in VT is unclear, it is a common occurrence and is significant in that it can occasionally mimic 'early' sites of endocardial activation, unless enough VT cycles are observed at a given site.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
- Physiology (medical)