Advanced AV block

An elderly c/o of dizziness. What is the rhythm?

Figure 1

The rhythm is sinus with a P to P rate of about 100. Some of the P's are hiding in the T waves and distorting it. So this is 3:1 AV block. This is high-degree AV (or advanced) AV block.

According to Dr. Goldberger, a subset of second degree heart block occurs when there are multiple consecutive nonconducted P waves present (P-QRS ratios of 3:1 or 4:1). This is referred to as high-degree (or advanced) AV block. It can occur at any level of the conduction system. A common misnomer is to call this pattern Mobitz II block.

This case went to complete heart block and a pacemaker was eventually inserted.

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