‘Trifascicular’ Block

Report:

Sinus rhythm

Left atrial abnormality (LAA)

First degree AV block

PR 0.28”

Left posterior hemiblock

Right bundle branch block

Old anterior infarction

Comment:

The term ‘trifascicular’ is sufficiently polysyllabic and scientific-sounding to continue in use despite the fact that the putative third ‘fascicle’ is, in most cases, the AV node itself, causing the first degree AV block.

The diagnosis of posterior hemiblock10 here, too, is a presumption - there is no certainty that the marked RAD (+145o) is not due to RVH. Most likely, in this patient with an old infarction and no specific reason for RVH, it is a true hemiblock. Its morphology should be compared to that of lateral MI causing the RAD.

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