1. New interpretation of fractionated electrogram (EG) activity and late potentials. Desynchrony in the appearance of the epicardial action potential second upstroke gives rise to fractionated epicardial EG activity, and concealed phase 2 reentry gives rise to high-frequency late potentials in the setting of Brugada syndrome (BrS). A. Shown are right precordial lead recordings and unipolar and bipolar EGs from the right ventricular outflow tract (RVOT) of a BrS patient. B. Electrocardiogram (ECG), action potentials from endocardium (Endo) and two epicardial (Epi) sites, and a bipolar epicardial EG (Bipolar EG) all simultaneously recorded from a coronary-perfused right ventricular wedge preparation treated with the Ito agonist NS5806 (5 μM) and the calcium channel blocker verapamil (2 μM) to induce the Brugada phenotype. Basic cycle length = 1000 milliseconds. C. Bipolar EGs recorded from the epicardial and endocardial surfaces of the RVOT in a patient with BrS. The epicardial EG displays fractionated electrogram activity as well as a high-frequency late potential (130 milliseconds delay). D. Bipolar EGs recorded from the epicardium and endocardium of a coronary-perfused wedge model of BrS, together with action potential recordings from an endocardial and two epicardial sites and a transmural ECG. Slow or delayed conduction was never observed. A and B, reproduced with permission from Nademanee K, Veerakul G, Chandanamattha P, et al: Prevention of ventricular fibrillation episodes in Brugada syndrome by catheter ablation over the anterior right ventricular outflow tract epicardium. Circulation Mar 29;123(12): C and D, reproduced with permission from Szél T, Antzelevitch C, et al: Abnormal repolarization as the basis for late potentials and fractionated electrograms recorded from epicardium in experimental models of Brugada syndrome. J Am Coll Cardiol May 20;63(19):
Source: MECHANISMS OF CARDIAC ARRHYTHMIAS AND CONDUCTION DISTURBANCES, Hurst's The Heart, 14e
Citation: Fuster V, Harrington RA, Narula J, Eapen ZJ. Hurst's The Heart, 14e; 2017 Available at: Accessed: October 07, 2017
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