High-output pacing in mapping of postinfarction ventricular tachycardia.
BACKGROUND
Pace mapping is used to identify critical areas for postinfarction ventricular tachycardia (VT). Unexcitable scar during pacing with standard output can identify borders of the reentry circuit. Unexcitable scar is not thought to contain surviving muscle fibers critical to the circuit. Due to current-to-load mismatch or a deep seated isthmus, higher power might be required in order to obtain capture.


OBJECTIVE
The purpose of this study was to evaluate the value of high-output pacing in patients with postinfarction VT.


METHODS
In a consecutive series of 18 patients (15 men, age 62 +/- 9, EF 0.29 +/- 0.15) with postinfarction VT, a voltage map was obtained and bipolar pace mapping was performed in areas with low voltage (<1.5 mV) at an output of 10 mA and 2 ms pulse width (PW). High-output capture was defined as capture that failed at these settings but succeeded at higher pacing output. The pacing output was increased to 20 mA at 2 ms, and the PW was increased to 10 ms as required to achieve capture.


RESULTS
Seventy-seven VTs were induced. Thirty-nine isthmus sites were identified. Focal areas with high-output capture were observed in 12/18 patients (output: 20 mA; mean PW: 7.3 +/- 3.5 ms). In 9/18 patients, this area was critical for the reentry circuit of 10 clinical VTs (23% of isthmus sites). In one third of patients, isthmus sites were identified only by high-output pacing.


CONCLUSIONS
High-output pacing can be helpful in identifying critical areas of postinfarction VT that otherwise may be missed.
Sarrazin
Jean-François
JF
Department of Cardiology, University of Michigan Health System, Ann Arbor, Michigan, USA.
Kuehne
Michael
M
Wells
Darryl
D
Chalfoun
Nagib
N
Crawford
Thomas
T
Boonyapisit
Warangkna
W
Good
Eric
E
Chugh
Aman
A
Oral
Hakan
H
Jongnarangsin
Krit
K
Pelosi
Frank
F
Morady
Fred
F
Bogun
Frank
F
D018780:Body Surface Potential Mapping / Q000379:methods*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D017115:Catheter Ablation; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications*; D017180:Tachycardia, Ventricular / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome