MECHANISM OF SPONTANEOUS TERMINATION OF STABLE ATRIAL-FLUTTER IN THE CANINE STERILE PERICARDITIS MODEL

Citation
J. Ortiz et al., MECHANISM OF SPONTANEOUS TERMINATION OF STABLE ATRIAL-FLUTTER IN THE CANINE STERILE PERICARDITIS MODEL, Circulation, 88(4), 1993, pp. 1866-1877
Citations number
24
Categorie Soggetti
Cardiac & Cardiovascular System",Hematology
Journal title
ISSN journal
00097322
Volume
88
Issue
4
Year of publication
1993
Part
1
Pages
1866 - 1877
Database
ISI
SICI code
0009-7322(1993)88:4<1866:MOSTOS>2.0.ZU;2-#
Abstract
Background. We tested the hypotheses that spontaneous termination of s table atrial flutter is directly related to spontaneous beat-to-beat c ycle length oscillations and that block of the circulating reentrant w ave front occurs in an area of slow conduction. Methods and Results. W e studied 30 episodes of spontaneous termination of stable atrial flut ter induced by atrial stimulation in 11 conscious, nonsedated dogs wit h sterile pericarditis. Additionally, in 5 dogs, 14 episodes of sponta neous termination of stable atrial flutter were studied with a multisi te mapping system to record simultaneously from 190 right atrial elect rodes. In the conscious-state studies, atrial flutter cycle length osc illations began 6+/-1 (mean+/-SEM) beats before termination in 26 epis odes, stable atrial flutter evolved into atrial fibrillation in 3 epis odes, and no cycle length change occurred before termination in 1 epis ode. In the open-chest studies, in all instances, spontaneous oscillat ions began 7+/-1 beats before termination. The only consistent oscilla tion pattern occurred for the last two beats: a long cycle length (149 +/-9 milliseconds) followed by a much shorter cycle length (110+/-6 mi lliseconds) (P<.01). Activation maps demonstrated that all cycle lengt h oscillations were explained by changes of conduction in an area(s) o f slow conduction in the reentrant circuit. In two instances, the last (short) cycle length was associated with disappearance of an area of slow conduction. In all episodes, the last circulating reentrant wave front blocked in an area of slow conduction in the reentrant circuit. Although not tested, during the last beat, the very early arrival of t he circulating reentrant wave front at an area of slow conduction sugg ests an important role for refractoriness, with head and tail interact ions, resulting in block. Conclusions. Spontaneous termination of stab le atrial flutter in the sterile pericarditis model (1) is preceded by beat-to-beat cycle length oscillations that result from changes in co nduction in areas of slow conduction in the reentrant circuit and (2) results from block of the circulating reentrant wave front in an area of slow conduction.