(origin, P and ORS locations and shape, PR interval,QRS - ? wide ? regular)
1. NSR (60-100/min)P-P and R-R intervals stable, similar P before QRS in each lead.
2. Sinus Tachycardia (>100/min) - consider fever, anxiety, pain, hypoxia, hyperthyroid, hypovolemia, bleeding, sepsis, PE, drug toxicity; and Sinus Bradycardia (< 60/min)
3. Sinus Arrhythmia - similar P's, normal P QRS T waves, variable rhythm, varies with respiration, not pathological, variable P-P interval, via vagal activity
4. PAC Premature Atrial Contraction, APB (atrial ectopic beat) - appears early with atrial P, +- abnormal P wave, generally normal QRS, not from SA node.
5. Atrial Flutter atrial rate 200 - 400/min, saw tooth pattern - F wave (best seen leads II and III), common ventricular rate 150/min (2:1 block with atrial rate 300/min)
6. Atrial Fibrillation Afib -- highly irregular rhythm, no discernible P waves, mildly irregular baseline, variable ventricular rate (brady tachycardia)
7. MAT Multifocal Atrial Tachycardia (TC) - 3 or more different P waves, normal QRSs, irregular rhythm; associated with COPD, hypoxia, Dig. or aminophylline toxicity, ASHD.
8. PSVT (Paroxysmal Supraventricular TC) 120 - 250/min; narrow QRS (<=0.10 sec); Wide QRS complex (> 0.10 sec) may exist with pre-existing bundle branch block, tachycardic induced bundle branch block, or with ventricular pre-excitation (WPW) with tachycardia; +-P waves - may be hidden in QRS complex.

• a. AV Nodal Reentrant TC: dual AV nodal pathways; P wave typically buried in QRS.
• b. AV Reentrant TC: accessory AV pathway; WPW Syndrome - PR < 0.10-0.12 sec, delta wave at beginning of QRS, QRS >= 0.12 sec, ? ST or T wave abnormalities.
• c. Accelerated Junctional TC: 60-125/min, automaticity of AV junction; inverted P waves in II, Ill, aVF (may be antegrade, retrograde, or buried); R/O critical illness, Dig. or theophylline toxicity, thoracic surgery, myocarditis, MI, hypokalemia.
• d. PAT (Paroxysmal Atrial TC) - P's identifiable, narrow QRS, 150 associated with Dig. toxicity, hypokalemia

9. AV Nodal Premature Contraction (AV Node ectopic beat) - generally normal QRS, negative or absent P wave.
10. PVC Premature Ventricular Contraction (ventricular ectopic beat) - early wide QRS, no P wave; note - danger with R on T phenomenon ( risk VTach/VFib).
11. Multifocal or Multiformed PVC's different PVC's (QRS) in same lead.
12. Bigeminy (coupled beat - atrial or ventr.): premature beat after every sinus beat.
13. Trigeminy: Sinus sinus premature sinus sinus premature
14. Ventricular TC V Tach, VT - >= 3 PVC's in a row, broad QRS rhythm at rate of 100 - 250/min; May be associated with capture or fusion beats, AV dissociation, LAD, NW axis, precordial concordance; QRS >= 0.14 - 0.16 sec; V1 with R-S wave or R-S-R'; R>R'.
15. Ventricular Fibrillation V Fib - extremely irreg. baseline, no discernible beats, BP = O.
16. Torsades de Pointes - twisting of QRS, prolonged QT interval, may progress to VFib.
17. Accelerated Idioventricular Rhythm AIVR - wide QRS, 50 - 100/min, seen with inferior MI, reperfusion arrhythmia, thrombolytics, warm up period, fusion beats, Dig. tox.