Sino-Atrial Exit Block

Report:

Sinus rhythm 52 – 54/min

Sino-atrial exit block

Bigeminy

Nonspecific T wave changes

Comment:

There are two long cycles. One is slightly longer, the other slightly shorter than twice the preceding P-P cycle. Allowing for some sinus arrhythmia, this could even be the rare type 2 (Möbitz) 2 sinoatrial exit block.

Below Fig 93a), in the only other available tracing, the long cycle is nearly double cycle lengths of the flanking short cycles. Fortunately, it matters less in the case of SA node than for distinguishing the type of AV block.

There are no blocked SVEBs in sight. This is the most important differential diagnosis.

The patient has a typical ECG of sick sinus syndrome.

Fig 93a.

Fig 94. Asymptomatic 46 year old lady also noted to have bigeminal pulse.

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