Upper rate behaviour

Behaviour of pacing at faster rates (only for DDD mode)

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This is influenced by the TARP

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TARP (total atrial refractory period)= AVI + PVARP

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Wenckebach response (when URI < TARP)

•As sinus rate increases, AV interval appears to progressively length until a p wave falls into the PVARP and a beat is dropped

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2:1 block response (when URI > TARP)

•As sinus rate increases, P falls into every 2nd PVARP resulting in 2:1 block