Sino-Atrial Exit Block

Report:

Sinus rhythm 74/min

3:2 sino-atrial exit block

Bigeminy

Negative U waves in lead 1

Comment:

The same comments can be made here as for the preceding Case 93. It, too, could have Möbitz 2 mechanism.

Below (Fig 94a) is another trace, with long cycles terminated by junctional escape beats. The unusual feature is the negative U wave in lead 1, discovered by perusing the trace for blocked SVEBs. It is also seen in Fig 94, but less obviously. This may be a sign of LAD artery disease, but I’ve only seen it in the precordial leads before.

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