Regular	Irregular
Narrow (< 0.12 seconds)	ST SVT A-Flutter (150 +/- 20)	A-Fib A-Flutter with variable AV conduction (regular morphology) MAT (varying atrial morphology)
Wide (> 0.12 seconds)	VT (no P waves) SVT with aberrant conduction ST with aberrant conduction A-Flutter with aberrant conduction	A-Fib with aberrant conduction +/- variable block A-Fib with WPW PVT

Atrial Flutter

• Atrial rate > 250

Wide QRS

• BBB or IVCD
  
• Pacemaker
• Tox (Sodium Channel Blockers)
• WPW
• Hyperkalemia
  

SVT

• SVTs from a sinoatrial source:
• Inappropriate sinus tachycardia
• Sinoatrial node reentrant tachycardia (SANRT)
• SVTs from an atrial source:
• Ectopic (unifocal) atrial tachycardia (EAT)
• Multifocal atrial tachycardia (MAT)
• Atrial fibrillation with a rapid ventricular response
• Atrial flutter with a rapid ventricular response
• SVTs from an atrioventricular source:
• AV nodal reentrant tachycardia (AVNRT) - causes 50-60% of SVT's
• Second conduction pathway but limited to AV Node
  
• AV reentrant tachycardia (AVRT) - 2nd most common cause of SVT
• Second conduction pathway extending between atrium and ventricle
  
• Includes WPW
  
• Junctional ectopic tachycardia

VT (should have rate > 120 bpm)

• NSVT terminates spontaneously without hemodynamic compromise
• Sustained VT lasts > 30 seconds, requires an intervention for termination or produces severe hemodynamic compromise or syncope before terminating spontaneously
• VT can convert with adenosine so it does not rule out VT (and thus rule in SVT with aberrancy)
• Beware mimics of VT (HR < 110)
  
• Hyperkalemia
• TCA, cocaine
• post-MI reperfusion arrhythmias

PVT (Polymorphic VT - multiple morphologies to beats)

• Torsades (must have underlying lonq QTc)
• non-Torsades (usually associated with ischemia but not long QTc)