Local Depolarization Abnormalities Are the Dominant Pathophysiologic Mechanism for Type 1 Electrocardiogram in Brugada Syndrome

Abstract

The type 1 BrS ECG is characterized predominantly by localized depolarization abnormalities, notably (terminal) conduction delay in the RV, as assessed with complementary noninvasive electrocardiographic techniques. We could not define a separate role for repolarization abnormalities but suggest that the typical signs of repolarization derangements seen on the ECG are secondary to these depolarization abnormalities.

Evolving J waves Prior to Ventricular Fibrillation Postoperative Coronary Bypass

“…In the present case, VF occurred during urination in the morning, and sinus tachycardia was observed before the onset, therefore, the secretion of catecholamine might be closely related to these mechanisms. Recently, not only early repolarization but depolarization abnormalities have been reported as a cause of J waves in Brugada syndrome (17,18). J waves due to depolarization abnormality were recorded in the right precordial leads (17), however, J waves were not shown in the right precordial leads in the present case.…”

“…If latent ischemia was a cause of the appearance of J waves, the decrease of L-type calcium currents and the increase of ATPsensitive potassium currents might be closely related as reported in the acquired Brugada syndrome (14) Prominent J waves were well produced during the canine wedge preparation due to augmented transient outward currents (Ito) which creates a transmural voltage gradient. This inhomogeneity of the membrane potential is believed to induce phase 2 reentry which leads to subsequently VF (15)(16)(17)(18). In the present case, VF occurred during urination in the morning, and sinus tachycardia was observed before the onset, therefore, the secretion of catecholamine might be closely related to these mechanisms.…”

The Brugada Syndrome Susceptibility Gene HEY2 Modulates Cardiac Transmural Ion Channel Patterning and Electrical Heterogeneity

“…35 However, the repolarization theory has been challenged by body surface potential mapping and by electric mapping in hearts of BrS patients. 21,36 These data rather support a depolarization theory which implicates conduction delay in the RVOT as a mechanism for the BrS ECG and arrhythmia. This hypothesis explains the electrocardiographic signs, the role of sodium channel mutation, and the mechanism of arrhythmogenesis.…”

“…Because the murine J wave is an expression of early repolarization 20 ; this indicated that early repolarization may differ between the WT and Hey2 +/− animals. To further investigate this, we recorded APs from cardiomyocytes isolated from the subepicardium and subendocardium of the RV (implicated in the pathophysiology of BrS [21][22][23] ) from both WT and Hey2 +/− mice (Figure 4A and 4B; Online Table IV). AP recordings in WT mice demonstrated a higher V max and APD in myocytes from subendocardium compared with subepicardium (P<0.05; Figure 4A and 4C).…”

Unmasking of J waves during Right Coronary Angiography in Patients with Spontaneous Coronary Spasms and Ventricular Fibrillation

“…As for the genesis of J waves, the transient increase in voltage gradient between the epicardium and endocardium is the likely mechanism (3) as proven experimentally in Brugada syndrome (9). In the present patients, J waves could have been the result of contrast-induced myocardial ischemia which augmented transient outward currents (known as "Ito currents").…”