Möbitz 2 Block

Report:

Sinus rhythm

Second degree AV block, Möbitz 2

Right bundle branch block

Comment:

The conducted P waves show no increment in their PR intervals prior to the blocked one - a clear-cut case of Möbitz 2 block. Typically, the QRS itself is prolonged, indicating an intraventricular site of the block. This is another manifestation of the BBBB the patient was known to have, historically (RBBB, then LBBB). Since its site is not likely to be affected by atropine, the block may in fact worsen following the administration of the drug (as the sinus rate increases).

The therapy of choice would be AV sequential pacing, since ventricular standstill is a distinct possibility. The patient would still die from the cardiogenic shock. This one did.

The pressure readouts on the strips are low, due, inter alia, to overzealous hæmofiltration.

Another noteworthy feature is the lack of tachycardia - a prognostically sinister chronotropic incompetence.

Fig 36a. More examples of Möbitz 2 AV block. All the conducted PR intervals are the same.

Fig 37. 37 year old jogger with progressive exertional angina over 6 weeks. His 12-lead ECG is normal except for a 1o AV block. He remains asymptomatic during the recording shown below.