Re: afib/bundle branch block Originally Posted by glasgow3 
The appearance on the monitor would vary depending upon the lead(s) being monitored and the rate. There are many references which offer probabilities as to whether certain observed characteristics in certain leads suggest ectopy or abberrancy. And as you observed, at higher rates it may become difficult to appreciate atrial fibrillation since the complexes may appear regular.
This patient, however, was well known to the cardiologist as having chronic atrial fibrillation with a bundle branch block. And since the cardiologist wrote a standing order for the cardizem, he clearly anticipated the possibility of a rapid ventricular response during this hospitalization. And by knowing his patient, he was able to order what "works" best/safest to achieve adequate rate control (which would be the goal in this case).
There are cookbook answers/algorithms for treatment of wide QRS tachycardias of uncertain origin. But obviously it would be more efficient to know exactly what you are dealing with....patient Hx, EKG and expert consultation with a cardiologist are appropriate in that regard.
Without trying to be flip, if a-fib it should be treated as a-fib (possibly digoxin, cardizem, or commonly used amiodarone etc. depending on the patient). Likewise if v-tach then treat as v-tach (probably amiodarone).
Of course, I am assuming that the patient is tolerating the rate which in most cases they will below 150/min; a severely symptomatic tachycardia will require emergent cardioversion regardless of its origin.
Finally, I would be curious as to when this patient's rate first exceeded 120/min since at the time you assumed care his rate was 145-148 and no drip running. Rapid ventricular rates can appear quite suddenly. On the other hand if the patient was allowed to cruise in the 130s for a period of time without intervention, I would complete an occurence report. The gradual response to the cardizem gtt without a bolus would likely have been a non-issue had it been initiated when the patient was in the 120s as ordered.
I know you mention 'depending on the pt' in your reply, but I just want to remind all to be leary of amiodarone in COPD pts's due to the risk of pulmonary fibrosis. This is mostly with longer term use but problems can occur during the bolus dosing too. (just my $0.02)
Also I agree with you on the cardizem gtt w/o a bolus--In this case the MD knew the pt but I've seen this order before from hospitalists who know nothing of the pt hx. If your serious about rate control order the bolus, repeat if needed and start the drip at 10ml/hr titrating to effect within drug limits. Another pet peeve...d/c ing cardizem gtt after pt converts and NOT ordering PO to maintain rate control/SR
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