A quantitative evaluation of refractoriness within a reentrant circuit during ventricular tachycardia. Relation to termination.

Abstract

Programmed ventricular stimuli introduced during sustained monomorphic ventricular tachycardia frequently reset the tachycardia, resulting in a less than fully compensatory pause. A resetting response curve is generated when the set of return cycles is evaluated as the function of the coupling intervals of the extrastimuli delivered during the ventricular tachycardia. If

Differential Effects of a Segment of Slow Conduction on Reentrant Ventricular Tachycardia in the Rabbit Heart

“…[32][33][34][35] In a study by Almendral et al 36 in 32 patients with chronic myocardial infarction, the 3 different reset patterns were approximately equally distributed. In another clinical study, Gottlieb et al 37 found that termination of VT by premature stimuli was more likely if the reentrant VT exhibited a sloped reset curve. VT cycle length did not determine the type of response during reset of the tachycardia.…”

Mechanisms of Resetting Reentrant Circuits in Canine Ventricular Tachycardia

“…[1][2][3][4][5][6] Flat portions were short, unlike in clinical responses where flat portions occur over as much as 50% of the cycle. 1 This difference may be related to different substrates forming reentrant circuits (discussed below).…”

“…Different resetting responses may be elicited clinically from different sites of stimulation, and termination of clinical ventricular tachycardia in response to premature simulation is dependent in part on the steepness of the response. 5 Boersma et al 11 were unable to demonstrate resetting in a rabbit model of anisotropic reentry and concluded that "it seems very unlikely that clinical tachycardia based on functional reentry can be reset." This disparity with our results reflects differences in the models of reentry that may have important clinical implications for understanding human ventricular tachycardia.…”

“…[1][2][3][4][5][6] Almendral et al 1 noted 3 resetting responses-flat, increasing, and mixed-based on changes in return cycles after progressively premature impulses. They postulated that a flat response indicated a fully excitable gap in the circuit; an increasing response, a partially excitable gap; and a mixed response, a combination of the two.…”

Alternation in the Fusion Complex during Constant Pacing of Sustained Ventricular Tachycardia.

“…T HE conductive properties of the atrioventricular (AV) node and the accessory pathway are relatively well known,1)-4) and dual pathways have been demonstrated as the cause of reentry in the AV node.4)- 6) In ventricular tachycardia (VT), resetting by a single extrastimulus7), 8) or transient entrainment9),10) might be used to disclose the conductive characteristic of the slow conduction zone, but data concerning the electrophysiologic properties of reentry circuits in human ventricular tachycardia have been recently accumulating.…”