Patients with branch blocks have very strange looking EKG when they pop into Afib with a rapid rate. However, a patient on chronic amio therapy usually points to a history of a-fib. It can be used in chronic suppression of V-tach as well, though at higher doses.
A lot of things can re-trigger a-fib and it can be a beast to get under control. Though sepsis can trigger a-fib, the sinus tachycardia seen in sepsis without a-fib is very unlikely to get into the 160's. A HR that high is usually an electrical issue.
The list of a-fib triggers in those with a history is extensive. But one of the primary culprits is electrolyte and acid base derangements. This lady with vomiting and diarrhea is losing potassium, hydrogen ions (acid) and bicarb (base).
Fluids were good, and though amio would be reasonable, it wouldn't do much until you got her derangements corrected.
V-tach in a patient with obvious pre-existing cardiac disease (LBBB, pacer, meds, etc) is unlikely to be tolerated with those kind of vitals.
