12-Lead EKG Rhythms

Normal Sinus Rhythm

• Regular rhythm

• 60-100 bpm

• QRS complexes are typically less than 100ms duration

• P waves are present and ALWAYS upright in leads I & leads II and inverted in aVR

Sinus Bradycardia

• Regular rhythm

• less than 60 bpm

• QRS complexes are typically less than 100ms duration

• P waves upright in lead I & II and inverted in aVR

Sinus Tachycardia

• Regular rhythm

• greater than 100 bpm

• QRS complexes are typically less than 100ms duration

• P waves are upright in leads I & II and inverted in aVR

Sinus Arrythmia

• Irregular rhythm, P-P (p to p interval) varies by more than 0.16 second

• QRA complexes are typically less than 100ms duration

• P waves are upright in leads I & II and inverted in aVR

Premature Atrial Complex

• P’ wave occurs before the next P wave was due

• P’ wave has a different appearance than the P wave

• After the PAC, there is often a small pause before the SA node resumes control

• QRS complex is usually identical to all other QRS complexes

AV Nodal Reentry Tachycardia (AVNRT)

• Regular rhythm

• Usually 140-220 bpm

• QRS is typically narrow

• P waves are often hidden in the QRS complex

Wolff-Parkinson-White Syndrome

• Short PR interval

• Delta wave; slurred upstroke to start QRS

• Prolonged QRS complex greater than 0.11s

• ST-T-Wave discordance

• Pseudo-infarction pattern

Paroxysmal Ectopic Atrial Tachycardia

• Regular rhythm

• greater than 100 bpm

• QRS complex is typically narrow (< .12s)

• P’ wave has a different morphology than the sinus beat

• Isoelectric baseline

• Often sudden in onset and sudden stop

Multifocal Atrial Tachycardia/Wandering Atrial Pacemaker

• Rhythm is irregularly irregular

• MAT rate greater than 100 bpm

• WAP rate less than 100 bpm

• Narrow QRS complex

• 3 or more distinct P’ waves in a single lead

Atrial Escape Beat/Rhythm

• occurs after delay in sinus activity

• P’ wave with different morphology than sinus beat, may be inverted

• Regular rhythm

• narrow QRS

• PR interval greater than .12s

Junctional Escape Beat/Rhythm

• occurs after delay in sinus activity

• regular rhythm

• narrow QRS complex

• P waves are absent or inverted immediately before or after QRS complex in lead II

• PR is less than .12s when present

Atrial Fibrillation

• irregularly irregular ventricular response

• ventricular rate is commonly 90-170 bpm

• QRS complex is narrow

• absence of isoelectric baseline

• no identifiable P waves

Atrial Flutter

• may have regular or irregular ventricular response

• ventricular rate is commonly 140-160 bpm but variable

• ventricular rate is a ratio of atrial rate, most commonly 2:1 AV ratio

• narrow QRS complex

• flutter or “sawtooth” waves

• absence of isoelectric baseline

Premature Ventricular Complexes

• no apparent P wave

• Premature QRS complex

• wide QRS (> .12s)

• bizarre

• ST-T wave discordance

• compensatory pause

Monomorphic Ventricular Tachycardia

• 3 or more consecutive PVCs w/ same morphology

• regular rhythm

• greater than 120 bpm

• wide QRS

• AV dissociation

Ventricular Fibrillation

• fibrillatory waves

• irregular

• 150-500 quivers/min

Torsades de Pointes

• “twisting of the points”

• irregular rhythm

• 150-22 bpm

• gradual shift in both axis and amplitude of QRS complex

• QT prolongation was cause

Ventricular Escape Rhythm

• regular rhythm

• no P waves wide QRS

• 20-50 bpm

Accelerated Idioventricular Rhythm

• regular rhythm

• absence of P waves

• wide QRS

• 60-100 bpm

First-Degree AV Block

• PR interval greater than .2s

• no missing QRS complexes

Second-Degree AV block Type/Wenckebach/Mobitz I

• progressive lengthening of the PR interval

• dropped QRS complexes

• grouped beating

Second-Degree AV Block Type II/Mobitz II

• constant PR interval

• dropped QRS

• QRS may be narrow or wide (more often wide)

• P waves march out at regular intervals

• the R-R of the dropped beat is an exact multiple of the preceding R-R interval

High-Grade AV Block

• AV ratio of 3:1 or greater

• P waves & QRS complexes are related to each other

Third-Degree AV Block

• P waves and QRS complexes have no relationship to one another

• random PR intervals