Slow and discontinuous conduction conspire in Brugada syndrome: a right ventricular mapping and stimulation study.
BACKGROUND
Brugada syndrome (BrS) is associated with lethal arrhythmias, which are linked to specific ST-segment changes (type-1 BrS-ECG) and the right ventricle (RV). The pathophysiological basis of the arrhythmias and type-1 BrS-ECG is unresolved. We studied the electrophysiological characteristics of the RV endocardium in BrS.


RESULTS
RV endocardial electroanatomical mapping and stimulation studies were performed in controls (n=12) and BrS patients with a type-1 (BrS-1, n=10) or type-2 BrS-ECG (BrS-2, n=12) during the studies. BrS-1 patients had prominent impairment of RV endocardial impulse propagation when compared with controls, as represented by: (1) prolonged activation-duration during sinus rhythm (86+/-4 versus 65+/-3 ms), (2) increased electrogram fractionation (1.36+/-0.04 versus 1.15+/-0.01 deflections per electrogram), (3) longer electrogram duration (83+/-3 versus 63+/-2 ms), (4) activation delays on premature stimulation (longitudinal: 160+/-26 versus 86+/-9 ms; transversal: 112+/-5 versus 58+/-6 ms), and (5) abnormal transversal conduction velocity restitution (42+/-8 versus 18+/-2 ms increase in delay at shortest coupling intervals). Wider and more fractionated electrograms were also found in BrS-2 patients. Repolarization was not different between groups.


CONCLUSIONS
BrS-1 and BrS-2 patients are characterized by wide and fractionated electrograms at the RV endocardium. BrS-1 patients display additional conduction slowing during sinus rhythm and premature stimulation along with abnormal transversal conduction velocity restitution. These patients may thus exhibit a substrate for slow and discontinuous conduction caused by abnormal active membrane processes and electric coupling. Our findings support the emerging notion that BrS is not solely attributable to abnormal electrophysiological properties but requires the conspiring effects of conduction slowing and tissue discontinuities.
Postema
Pieter G
PG
Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
van Dessel
Pascal F H M
PF
de Bakker
Jacques M T
JM
Dekker
Lukas R C
LR
Linnenbank
Andre C
AC
Hoogendijk
Mark G
MG
Coronel
Ruben
R
Tijssen
Jan G P
JG
Wilde
Arthur A M
AA
Tan
Hanno L
HL
D000200:Action Potentials; D000328:Adult; D053840:Brugada Syndrome / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial; D016022:Case-Control Studies; D022062:Electrophysiologic Techniques, Cardiac; D004699:Endocardium / Q000503:physiopathology*; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012815:Signal Processing, Computer-Assisted