Eponyms

Ashman Phenomenon

RBBB in AMI = pLAD

Ashman Phenomenon: usually in Af, a wide QRS, usually an RBBB, that terminates a short cycle that follows a long cycle (long R-R). link/photo/pdf

"the earlier the PAC occurs in the cycle, and the longer the preceding cycle, the more likely the PAC will be conducted aberrantly"

- because the longer the preceding cycle (the slower the heart rate), the longer the refractory period, therefore the PAC terminating the short cycle. occurs in the refractory period, hence, it will be aberrant (wide).

therefore occurs in long-short cycle, but even more common in short-long-short cycle.

Right Bundle recovers slower (longer refractory period) then Left Bundle, that's why the most likely from is RBBB.

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Fisch criteria to differentiate from ventricular ectopic.

Wikipedia: It occurs because the duration of the refractory period of the myocardium is proportional to the R-R interval of the preceding cycle. A short R-R interval is associated with a shorter duration of action potential and vice versa. A long R-R cycle will prolong the ensuing refractory period, and if a shorter cycle follows, the beat terminating the cycle is likely to be conducted aberrantly. Because the refractory period of the right bundle branch is longer than the left, the right bundle will still be in the refractory period when the supraventricular impulse reaches the His-Purkinje system, resulting in a complex with right bundle branch morphology.

RBBB in AMI = pLAD

- because R bundle is supplied by first septal perforator which is the most proximal branch of LAD (usually that is, sometimes it arises after D1, but usually before D1)

- RBBB in AMI is also a poor prognosis