In a patient with complete AV block and TdP, magnesium suppressed tachycardia without affecting EADs or QT interval, while pacing and lidocaine suppressed EADs and shortened the QT interval.
We present a patient with complete atrioventricular block and torsades de pointes in whom early afterdepolarization (EAD) was demonstrated in right ventricular monophasic action potentials (MAPs). In an emergency situation, MAPs were recorded after the suppression of torsades de pointes by magnesium injection. EADs were observed at three out of five right ventricular sites during escape rhythm. Thus, magnesium abolished the tachycardia without shortening the QT interval and probably without suppressing EAD. Right ventricular pacing and the injection of lidocaine (50 mg) suppressed EAD and shortened the QT interval.
Kurita et al. (Fri,) studied this question.
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