This middle-aged patient presented with SOB, weakness, and mild pulmonary edema.

This middle-aged patient presented with SOB, weakness, and mild pulmonary edema.She previously had Atrial fibrillation with LBBB.Here is her ED ECG:Does this reveal the etiology of her symptoms?This shows atrial fibrillation.  There is a regular, slow response.  The fact that the response is regular proves that the atrial fibrillation is NOT conducting.  When atrial fib conducts, the ventricular rate must always be irregular.This is atrial fibrillation with complete (3rd degree) AV block.The QRS morphology is RBBB with a vertical axis.  This suggests an LV escape rhythm, possibly from the left anterior fascicle.She previously had known LBBB, so she is lucky that her left sided escape can make it out of the LV through the left sided conducting system to the right side.  She could have developed an escape that is not able to use the conducting system at all; such an escape would be very wide and bizarre, with uncertain efficacy.  She could even have developed asystole.There are 3 etiologies I always think of with bradycardia and AV block:1. Medications -- she had been on metoprolol for 4 years at the same dose, so this is unlikely to be the etiology2. Hyperkalemia.  Her K was normal3. Ischemia.  There was no evidence of ischemia.Thus, this is a sick AV node.She had a permanent pacemaker implanted.After pacer AND conversion to sinus rhythm:Computer diagnosis:p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 10.0px ' Courier New ' } p.p2 {margin...
Source: Dr. Smith's ECG Blog - Category: Cardiology Authors: Source Type: blogs