SVT Rate: 150bpm with no visible P waves (AHA 2011 Guidelines). Unstable patients needs immediate Synchronized Cardioversion. The machine synchronizes itself to your patients ventricular depolarization (QRS) but shock upon discharge on the relative refractory period during ventricular repolarization (downslope of the the T wave). This prevents an R-on-T Phenomenon (causes dysrhythmias). SVT, Atrial Flutter and PSVT responds better to Biphasics: 50-100 Joules for the first shock. If using Monophasics: charge to 100-200 J to synchronized shock. This stuns all irritated sites hoping the inherent pacemaker (SA Node) takes over.

If electrical cardioversion is unsuccessful, switch to medical cardioversion (Beta-blockers, Calcium Channel Blockers, Anti-arrhythmics).