EKG

EKG Interpretation Study Guide

Sinus Rhythms

• SR (Sinus Rhythm): Regular, rate 60–100 bpm, has P-QRS-T

• SB (Sinus Bradycardia): Regular, rate <60 bpm

• ST (Sinus Tachycardia): Regular, rate >100 bpm

• SA (Sinus Arrhythmia): Irregular, any HR; rhythm not the same

• Sinus Pause: 0.15–3 sec pause

• Sinus Arrest: 3 seconds or more

Atrial Rhythms

• PAC (Premature Atrial Contraction): Early beats, different types of P waves

• WAP (Wandering Atrial Pacemaker): Rate <100, regular, different P wave morphologies

• MAT (Multifocal Atrial Tachycardia): Rate >100, different types of P waves

• SVT (Supraventricular Tachycardia): Rate >100, regular, buried P wave

• Atrial Tachycardia: HR ≥150 bpm, with hard-to-see P wave

• Atrial Flutter: Regular, sawtooth pattern, flutter (F) waves instead of P waves

• Atrial Fibrillation: Irregular, no true P waves, chaotic baseline; controlled if HR <100, uncontrolled if HR >100

Junctional Rhythms

• PJC (Premature Junctional Contraction): Inverted/absent P wave

• Junctional Rhythm: Rate 40–60 bpm, regular, inverted P wave

• AJ (Accelerated Junctional): Rate 61–100 bpm

• JT (Junctional Tachycardia): Rate >100 bpm

Ventricular Rhythms

• PVC (Premature Ventricular Contraction): Early wide bizarre QRS, inverted T wave; may be unifocal, multifocal, or in patterns like bigeminy/trigeminy

• Fusion Beat: Two beats in one

• IVR (Idioventricular Rhythm): Wide bizarre QRS, HR 20–40 bpm

• AIVR (Accelerated Idioventricular Rhythm): HR 40–100 bpm, low amplitude

• V-Tach (Ventricular Tachycardia):

• Monomorphic: Same QRS shape

• Polymorphic (Torsades de Pointes): Different QRS shapes

• V-Fib (Ventricular Fibrillation): No cardiac activity, coarse/fine waves

• Asystole: Flatline, no electrical activity

Heart Blocks

• 1st Degree Block: PR interval >0.20 sec, consistent

• 2nd Degree Type I (Wenckebach): PR interval gets longer until QRS drops

• 2nd Degree Type II (Mobitz II): Constant PR interval, random dropped QRS. Usually low heart rate

• 3rd Degree Block (Complete Heart Block): Atria and ventricles beat independently, inconsistent PR interval

Bundle Branch Blocks

• RBBB (Right Bundle Branch Block): QRS >0.12 sec, bunny ear pattern

• LBBB (Left Bundle Branch Block): Wide QRS, notched/slurred

Pacemakers

• A-paced: Pacer spike before P wave

• V-paced: Pacer spike before QRS

• AV/Dual Paced: Pacer spikes before both P wave and QRS

• Bi-Ventricular Paced: Two pacers fire every QRS

• On Demand: Pacer only fires when needed (e.g., heart doesn’t beat)

• Failure to Capture: Spike but no QRS follows (no conduction)

• Failure to Sense: Pacer fires at wrong time (can’t see rhythm)

• Failure to Pace/Fire: Pacer doesn’t fire when needed

Pacemaker Malfunctions

• Undersensing: Pacer doesn’t recognize intrinsic activity (fires too late or too slow)

• Oversensing: Pacer is too sensitive and doesn’t fire

• Failure to Fire: Pacer fails to initiate an impulse

• Failure to Capture: Spike is seen, but heart does not respond