Does This Patient Need a Pacemaker?
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This tracing shows blocked P waves with no appreciable lengthening of the PR interval in the conducted beats. Is a pacemaker indicated?
DiscussionNo is the correct answer:
Around the time when the P wave is blocked, the P-P interval significantly lengthens. This suggests that it is not an intrinsic AV conduction problem but that some "force" extrinsic to the heart is causing the sinus node to slow down on the one hand and the AV block to occur on the other. The extrinsic "force" is an increased vagal tone. This phenomenon is seen sometimes in well trained athletes who usually have an increased vagal tone that is benign. A pacemaker is not necessary. Thus, during AV block, paying attention to what the P-P interval is doing is useful in understanding what is happening so that the person can be treated appropriately.