High-resolution mapping demonstrates that tachycardia originating from the superior vena cava can be driven by circus movement reentry with marked slow and anisotropic conduction, suggesting a similar mechanism may exist in pulmonary veins.
Reentry around SVC block documented in one case; hypothesis-generating for analogous circuits in pulmonary veins, should not yet alter ablation practice.
Superior Vena Cava Reentry. High-resolution mapping of a tachycardia originating from the superior vena cava (SVC) in a patient with atrial fibrillation is described. Unidirectional circuitous repetitive activation encompassing the full tachycardia cycle length was documented around a line of block within the myocardial sleeve of the SVC. Intermittent conduction to the right atrium resulted in an irregular atrial tachycardia. Evidence of electrical heterogeneity and slow conduction persisted in sinus rhythm and was exaggerated by premature stimulation but did not reproduce the activation pattern during tachycardia. All the available evidence is best compatible with circus movement reentry within the SVC, with marked slow and anisotropic conduction responsible for the restricted dimensions of the reentrant circuit. These findings may suggest a similar substrate and arrhythmia mechanism in the myocardium of the pulmonary veins.
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Shah et al. (2002) studied this question.
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