Prevalence of a shared isthmus in postinfarction patients with pleiomorphic, hemodynamically tolerated ventricular tachycardias.
BACKGROUND
Multiple forms of ventricular tachycardia (VT) after myocardial infarction may result from multiple reentrant circuits that share an isthmus or from separate reentrant circuits. The prevalence of a shared isthmus in patients with multiple hemodynamically tolerated VTs has not been determined.


RESULTS
Criteria for a shared isthmus consisted of (1) concealed entrainment of >1 VT at a single pacing site; (2) concealed entrainment during VT and a perfect pace map of another VT at the same pacing site; or (3) concealed entrainment of VT of a given morphology that had at least two cycle lengths that varied by at least 100 msec. In a series of 19 patients (16 men and 3 women; age 65+/-14 years, ejection fraction 0.25+/-0.09) with 54 VTs (mean cycle length 494+/-98 msec), there was evidence of a shared isthmus in 23 VTs (43%) at 11 sites in 9 patients. Concealed entrainment of two different VTs was observed at 4 of 11 sites. At 5 of 11 sites there was concealed entrainment of one VT and a perfect pace map of another VT. At the remaining 2 of 11 sites, there was concealed entrainment of a VT that had two different cycle lengths. Nineteen of the 23 VTs were ablated successfully with radiofrequency energy applications at 11 sites.


CONCLUSIONS
In postinfarction patients with pleiomorphic, hemodynamically stable VT, a shared isthmus may be present in approximately 40% of VTs.
Bogun
Frank
F
Division of Cardiology, Henry Ford Hospital, Detroit, Michigan 48202-9888, USA. bogun@eudormail.com
Li
Yi-Gang
YG
Groenefeld
Gerian
G
Hohnloser
Stefan H
SH
Schuger
Claudio
C
Oral
Hakan
H
Pelosi
Frank
F
Knight
Bradley
B
Strickberger
S Adam
SA
Morady
Fred
F
D000368:Aged; D017115:Catheter Ablation; D016009:Chi-Square Distribution; D003971:Diastole / Q000502:physiology; D004562:Electrocardiography; D004594:Electrophysiology; D005260:Female; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000150:complications*; D017180:Tachycardia, Ventricular / Q000209:etiology* / Q000503:physiopathology* / Q000601:surgery