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Figure 2.
Adenosine blocks the AV ARQ197 and can highlight the presence or the absence of an accessory pathway. (a) The upper trace shows an apparently normal QRS at the start, which becomes broader with the pattern of Wolff–Parkinson–White syndrome. The AV node is blocked and activation spreads preferentially down the pathway. The pathway is on the extreme left-hand side of the heart, so that at rest most of the ventricles are activated by the AV node and the QRS therefore appears narrow. (b) The lower panel shows AV block after adenosine thus excluding a potentially dangerous, antegradely conducting accessory pathway.
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Some9 have proposed Schwann cells patients in whom adenosine produces a very prolonged pause may be especially susceptible to blackout, often presenting with AV block but without obvious structural AV nodal disease. However, the use of adenosine in the general assessment of syncopal patients remains controversial.
Electrophysiological studies (EPS)
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