Mechanism of right precordial ST-segment elevation in structural heart disease: excitation failure by current-to-load mismatch.

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Hoogendijk MG, Potse M, Linnenbank AC, Verkerk AO, den Ruijter HM, van Amersfoorth SC, Klaver EC, Beekman L, Bezzina CR, Postema PG, Tan HL, Reimer AG, van der Wal AC, Ten Harkel AD, Dalinghaus M, Vinet A, Wilde AA, de Bakker JM, Coronel R

Mechanism of right precordial ST-segment elevation in structural heart disease: excitation failure by current-to-load mismatch.

Heart Rhythm. 2010;7(2):238-48. doi: 10.1016/j.hrthm.2009.10.007. Epub 2009 Oct 12.

PubMed ID

20022821 [ View in PubMed

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Abstract

BACKGROUND: The Brugada sign has been associated with mutations in SCN5A and with right ventricular structural abnormalities. Their role in the Brugada sign and the associated ventricular arrhythmias is unknown. OBJECTIVE: The purpose of this study was to delineate the role of structural abnormalities and sodium channel dysfunction in the Brugada sign. METHODS: Activation and repolarization characteristics of the explanted heart of a patient with a loss-of-function mutation in SCN5A (G752R) and dilated cardiomyopathy were determined after induction of right-sided ST-segment elevation by ajmaline. In addition, right ventricular structural discontinuities and sodium channel dysfunction were simulated in a computer model encompassing the heart and thorax. RESULTS: In the explanted heart, disappearance of local activation in unipolar electrograms at the basal right ventricular epicardium was followed by monophasic ST-segment elevation. The local origin of this phenomenon was confirmed by coaxial electrograms. Neither early repolarization nor late activation correlated with ST-segment elevation. At sites of local ST-segment elevation, the subepicardium was interspersed with adipose tissue and contained more fibrous tissue than either the left ventricle or control hearts. In computer simulations entailing right ventricular structural discontinuities, reduction of sodium channel conductance or size of the gaps between introduced barriers resulted in subepicardial excitation failure or delayed activation by current-to-load mismatch and in the Brugada sign on the ECG. CONCLUSION: Right ventricular excitation failure and activation delay by current-to-load mismatch in the subepicardium can cause the Brugada sign. Therefore, current-to-load mismatch may underlie the ventricular arrhythmias in patients with the Brugada sign.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Ajmaline	Sodium channel protein type 5 subunit alpha	Protein	Humans	Yes	Inhibitor	Details