Accessory pathway re-entry and ventricular ectopic beats
THE CONTEXT
This passage explains how an accessory pathway permits re-entry tachycardia and describes the ECG appearance and pulse effect of ventricular ectopic beats.
Accessory pathway re-entry
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Differences in conduction speed and refractory period between the atrioventricular (AV) node and accessory pathway allow a re-entry circuit to develop, causing tachycardia.
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When associated with symptoms, the condition is called Wolff–Parkinson–White (WPW) syndrome.
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The ECG during this tachycardia can be indistinguishable from that of AV nodal re-entrant tachycardia (AVNRT).
Ventricular ectopic beats
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Ventricular ectopic beats appear as broad, bizarre QRS complexes without a preceding P wave, occurring between normal sinus beats.
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Variation in the configuration of the ectopic QRS complexes identifies multifocal ectopics.
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Ectopic beats produce a weaker arterial pulse, which may be perceived as a dropped beat.