Ventricular Fibrillation Resulting from Acute Right Ventricular Infarction from Isolated Occlusion of a Right Ventricular Branch Artery

This study determined the role of a slowly inactivating component of sodium current (I(Na)), late I(Na), to induce delayed afterdepolarizations (DADs) and triggered activity. We hypothesized that an increase of late I(Na) may induce not only early afterdepolarizations (EADs), but also intracellular calcium overload and DADs. Guinea pig atrial myocytes were studied using the whole cell patch-clamp technique. Anemone toxin II (ATX-II) (5-10 nmol/l) was used to enhance late I(Na). Ranolazine (10 micromol/l) and TTX (2 micromol/l) were applied to block ATX-II-induced late I(Na). ATX-II prolonged action potential duration and induced EADs. In the continuous presence of ATX-II, following the appearance of EADs, both DADs and sustained triggered activity occurred. Triggered activity was abolished and DADs were reduced by either ranolazine or TTX. Consistent with induction of DADs, ATX-II induced the transient inward current (I(TI)). The amplitude of I(TI) was significantly reduced by ranolazine. ATX-II induced only EADs, but no DADs, in the presence of the sodium-calcium exchange inhibitor KB-R7943 or the sarcoplasmic reticulum calcium release channel inhibitor ryanodine, or when the calcium chelator EGTA or BAPTA was included in the pipette solution. In conclusion, an increase of late I(Na), in addition to inducing EADs, can cause cellular calcium overload and induce DADs and sustained triggered activity in atrial myocytes. The data reveal that an increase of late I(Na) is a novel mechanism for initiation of atrial arrhythmic activity.

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Genome-Wide Linkage Scan Identifies a Novel Genetic Locus on Chromosome 5p13 for Neonatal Atrial Fibrillation Associated With Sudden Death and Variable Cardiomyopathy

Oberti

Wang

et al. 2004

Circulation

111

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Background-Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, and patients with AF have a significantly increased risk for ischemic stroke. Approximately 15% of all strokes are caused by AF. The molecular basis and underlying mechanisms and pathophysiology of AF remain largely unknown. Methods and Results-We have identified a large AF family with an autosomal recessive inheritance pattern. The AF in the family manifests with early onset at the fetal stage and is associated with neonatal sudden death and, in some cases, ventricular tachyarrhythmias and waxing and waning cardiomyopathy. Genome-wide linkage analysis was performed for 36 family members and generated a 2-point logarithm of the odds (LOD) score of 3.05 for marker D5S455. The maximum multipoint LOD score of 4.10 was obtained for 4 markers: D5S426, D5S493, D5S455, and D5S1998. Heterozygous carriers have significant prolongation of P-wave duration on ECGs compared with noncarriers (107 versus 85 ms on average; Pϭ0.000012), but no differences between these 2 groups were detected for the PR interval, QRS complex, ST-segment duration, T-wave duration, QTc, and R-R interval (PϾ0.05). Conclusions-Our findings demonstrate that AF can be inherited as an autosomal recessive trait and define a novel genetic locus for AF on chromosome 5p13 (arAF1). A genetic link between AF and prolonged P-wave duration was identified. This study provides a framework for the ultimate cloning of the arAF1 gene, which will increase the understanding of the fundamental molecular mechanisms of atrial fibrillation.

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Ventricular Fibrillation Resulting from Acute Right Ventricular Infarction from Isolated Occlusion of a Right Ventricular Branch Artery

Cited by 4 publications

References 11 publications

Isolated Right Ventricular Infarct Presenting as Ventricular Fibrillation Arrest and Confirmed by Delayed-Enhancement Cardiac MRI

Isolated Right Ventricular Infarct Presenting as Ventricular Fibrillation Arrest and Confirmed by Delayed-Enhancement Cardiac MRI

An increase of late sodium current induces delayed afterdepolarizations and sustained triggered activity in atrial myocytes

Genome-Wide Linkage Scan Identifies a Novel Genetic Locus on Chromosome 5p13 for Neonatal Atrial Fibrillation Associated With Sudden Death and Variable Cardiomyopathy

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