The narrow complex tachycardias, for all practical purposes are SVTs. If patient is hemodynamically unstable due to it, treatment- as in any unstable patient is Electrical cardioversion. If the patient is relatively stable, then the DOC is Adenosine (6»12»12 mg in sequence) The most important part about injecting adenosine is that it should be administered RAPIDLY with one quick push followed by a saline flush through inj.

Since Adenosine blocks the AV node, it can cause transient asystole because the atrial impulse will not be conducted through to the ventricle and the ventricular escape takes some time to establish. Adenosine is very short acting therefore there is rapid recovery of impulse transmission except in patients with Sick sinus syndrome whose conducting system is slow to recover and those who are on Dipyridamole (Persantine) because Persantine prolongs its half life. If one runs into bronchospasm due to it, Aminophylline is the DOC to treat it. Therefore it is contra-indicated in Asthma.