Cannon A Waves on Neck Examination

Cannon a waves! Notice that it occurs randomly, not predictably w/ the cardiac cycle or respiration. Cannon a waves indicate AV dissociation: 3rd deg AV block, or, as this case, VVI (asynchronous) pacing.
The patient had a dual-chamber PPM set for DDI and an atrial tachycardia much faster than the PPM’s max tracking rate.

Vivek Kulkarni MD @VivekKulkarniMD

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