The variable contribution of functional and anatomic barriers in human ventricular tachycardia: an analysis with resetting from two sites
Abstract
This study sought to investigate the influence of stimulation site on the properties of the circuit in ventricular tachycardia. A fully excitable gap can be demonstrated in most human ventricular tachycardias. This requires the presence of an arc of block so that the entire circuit can recover from refractoriness within the period of the cycle length. Resetting characterizes the conduction properties of the tissue within the ventricular tachycardia circuit. Previous studies have not investigated the possibility of site-dependent differences in the resetting response. Resetting was performed from the right ventricular apex and outflow tract in 23 patients. Two characteristics of the resetting response were analyzed: 1) the total duration of the flat portion, and 2) the slope of the increasing portion. A flat portion of the resetting response was observed in 18 tachycardias; in 8 of the 18, there was a significant site-dependent difference (> or = 40 ms) in the duration of the flat portion. A significant site-dependent difference in the slope of the increasing portion of the resetting curve was seen in 6 of 22 tachycardias. In all, a stimulation site-dependent change in at least one characteristic of the resetting response was se...Continue Reading
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