This case demonstrates a rare mechanism of nonreentrant supraventricular tachycardia caused by simultaneous anterograde fast and slow conduction through dual AV nodal pathways leading to double ventricular responses to single P-waves.
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Recognizes rare nonreentrant SVT from dual AV nodal 1:2 conduction; leaves open prevalence and management implications pending larger studies.
Noninvasive recordings in a 69-year-old woman showed two distinct PR intervals of about 0.21 and 0.58 s, suggestive of dual AV nodal conduction. Various unusual mechanisms of transition from short to long and from long to short conduction intervals and phenomena of concealed conduction were due to the presence of two functionally separated intranodal pathways. Refractoriness of the slow pathway was associated with bradycardia. Episodes of tachycardia exhibited a one-to-two relationship between P-waves and ventricular activations as a consequence of simultaneous anterograde fast and slow conduction leading to double ventricular responses to single P-waves.
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Buss et al. (1985) studied this question.
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