The electrophysiologic mechanism of ST-segment elevation in Brugada syndrome.
OBJECTIVE
We sought to demonstrate the electrophysiologic (EP) mechanism of the ST-T change in Brugada syndrome.


BACKGROUND
Brugada syndrome is characterized by various electrocardiographic manifestations (e.g., right bundle branch block, ST-segment elevation, and terminal T-wave inversion in the right precordial leads) and sudden cardiac death caused by ventricular fibrillation. Direct evidence in support of the EP mechanism underlying this intriguing syndrome has been lacking.


METHODS
Monophasic action potentials (MAPs) were obtained from three patients with the coved-type ST-segment elevation (Brugada patients) and five control patients using the contact electrode method. Epicardial MAPs were recorded during open-chest surgery in all patients.


RESULTS
A spike-and-dome configuration was documented from epicardial sites of the right ventricular (RV) outflow tract in all Brugada patients but not in control patients. Monophasic action potential recordings from the endocardium with special focus on the RV outflow tract could not demonstrate any morphological abnormalities in three Brugada patients.


CONCLUSIONS
The presence of a deeply notched action potential in the RV epicardium, but not in endocardium, would be expected to induce a transmural current that would contribute to elevation of the ST-segment in the right precordial leads. The spike-and-dome configuration may also prolong the epicardial action potential, thus contributing to a rapid reversal of the transmural gradients and inscription of an inverted T-wave.
Kurita
Takashi
T
Division of Cardiology, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan. kuritat@hsp.ncvc.go.jp
Shimizu
Wataru
W
Inagaki
Masashi
M
Suyama
Kazuhiro
K
Taguchi
Atsushi
A
Satomi
Kazuhiro
K
Aihara
Naohiko
N
Kamakura
Shiro
S
Kobayashi
Junjiro
J
Kosakai
Yoshio
Y
D000368:Aged; D002037:Bundle-Branch Block / Q000235:genetics / Q000503:physiopathology*; D016022:Case-Control Studies; D004562:Electrocardiography; D004594:Electrophysiology; D006329:Heart Conduction System / Q000503:physiopathology*; D006331:Heart Diseases / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D062554:NAV1.5 Voltage-Gated Sodium Channel; D012107:Research Design; D015222:Sodium Channels / Q000235:genetics; D013577:Syndrome; D013610:Tachycardia / Q000503:physiopathology
D062554:NAV1.5 Voltage-Gated Sodium Channel; C568320:SCN5A protein, human; D015222:Sodium Channels