A Woman in Her 50s With Chest Pain and Lightheadedness and "Anterior Subendocardial Ischemia"
Highlights
- QRS will almost always be wide when there is Mobitz II (View Highlight)
- AV dissociation is never a “diagnosis”. Instead — it is a condition caused by “something else” (View Highlight)
- There are 3 Causes of ../../../Knowledge/Medicine/AV Dissociation: i**)** AV Block itself (of 2nd- or 3rd-degree); ii) "Usurpation" — in which P waves transiently do not conduct because of an accelerated junctional rhythm that takes over (ie, “usurps” control of the rhythm); and, iii**)** "Default" — in which a junctional escape rhythm takes over by “default” (ie, because of SA node slowing) — as may occur if a medication such as a ß-blocker is being used (View Highlight)
- The KEY to determining if any AV block at all is present — is to determine IF P waves fail to conduct despite having adequate opportunity to do so (View Highlight)
- Most of the time, IF the degree of AV block is complete (3rd-degree) — then the ventricular rhythm should be regular (or at least fairly regular). This is because escape rhythms arising from the AV node, the His or ventricles are usually fairly regular rhythms (View Highlight)
- The BEST clue that there is at least some conduction — is IF in the presence of AV dissociation, you see one or more beats that occur earlier-than-expected (View Highlight)
- when there is acute posterior OMI and some form of 2nd-degree AV block with a narrow QRS — that this is almost certain to be some form of AV Wenckebach (View Highlight)