CFIT ECG interpretations

P wave

atrial depolarization

QRS complex

ventricular depolarization

T wave

ventricular repolarization

1 little box

40 ms

one big box

200 ms

PR normal interval

120-200 ms

QRS normal interval

80-120 ms

QTc male normal interval

<420

QTc female normal interval

<440

Normal Sinus Rhythm

• heart rate 60-100

• P-QRS-T on ECG

• QRS preceded by P wave

• all intervals are normal

• P wave normal

• SA node

sinus bradycardia

• rhythm regular

• heart rate <60 bpm

• originates from SA node

• normal P wave

• PR normal

• QRS normal

sinus tachycardia

• heart rate >100 bpm

• SA node

• rhythm regular

• Normal upright P wave

• 1 P wave per 1 QRS

• PR normal

• QRS normal

sinus arrhythmia

• heart rate varies with patients breathing

• varying P-P interval

• irregular rhythm

• PR constant

sinus pause

• SA node temporarily fails to depolarize

• still have P waves

• long pause between complexes

sinus arrest

• >3 seconds of SA node failure to depolarize

• loss of P waves

• significant pause before the next impulse

junctional escape

delayed heart beat coming from ectopic focus in the AV junction (NOT SA node)

SA exit block

• usually have sinus pause

• dropped P waves

• some QRS complexes

1^o AV block

• rhythm regular

• heart rate normal

• P wave conducts, just takes awhile

• long PR interval

• 1:1 conduction

• QRS normal

2^o AV block Type I

• wenckebach

• PR gets longer and longer then block occurs

• more P than QRS

• QRS blocked after prolonged PR interval

• atrial rate regular

• ventricular rhythm irregular

• P wave normal

• QRS normal

2^o AV block Type II

• rhythm regular or irregular

• PR constant on conductions beats

• QRS usually wide due to bundle branch block

• P wave normal

• more P waves than QRS

3^o AV block (complete heart block)

• P wave normal shape

• PR variable but not constant

• regular P-P and R-R, but they are dissociated from each other

• independent atrial and ventricular rate

• more P than QRS

• QRS normal or widened depending on where it escaped at bundle of his

PACs (premature atrial contractions)

• P wave morphology different can be flattened, peaked, or notched

• QRS narrow

• compensatory pause after PAC

• T waves are more peaked = P wave is in it

• rhythm irregular where PAC occurs

• PR interval shortened or longer

• rhythm can be normal or vary

couplet

2 premature beats in a row

triplet

3 premature beats in a row

bigeminy

every other beat is premature

trigeminy

every 3rd beat is premature

compensatory pause

long pause after an abnormal beat

PVCs (premature ventricular contractions)

• large, weird looking QRS

• P wave present

• compensatory pause

• heart rate normal

• rhythm irregular

PVCs multifocal QRS

• appear different form one another

• multiform because they originate from multiple sites in the ventricles

PVCs unifocal QRS

• originate from one spot

• uniform in shape across beats and have a consistent morphology

• wide and ugly QRS

PJCs

• narrow QRS

• P waves inverted

• QRS not preceded by P wave (in the QRS)

• regular underlying rhythm

A.T (atrial tachycardia)

• form of SVT

• P and T wave combine

• fast heart rate (arrhythmia)

SVT (supraventricular tachycardia)

• P and T waves combine

• fast and narrow QRS

• heart rate 150-250 bpm

• typically have a regular rhythm

• monomorphic

• regular might be slightly irregular

• PR not measurable or short

• QRS narrow

atrial flutter

• 225-350 bpm

• P and T waves combined

• sawtooth pattern

• organized arrhythmia

• regular- 2:1, 3:1, 4:1, etc

• regularly irregular- alternating 2:1 and 3:1

• irregularly irregular- no pattern

• QRS normal

• T wave hidden in flutter

• PR not measurable

Afib (atrial fibrillation)

• irregularly irregular

• no predictable R wave pattern

• P and T waves combined

• R-R intervals not consistant

• ventricular rate varies

• PR is not measurable

• QRS narrow

junctional rhythm

• narrow QRS

• P wave abnormal in shape or inverted or hidden

• heart rate 40-60 bpm

• rhythm regular

• PR <0.12s

VTACH (ventricular tachycardia)

• heart rate 100-120 bpm

• rhythm usually regular, slightly irregular

• can be sustained, non-sustained, monomorphic, or polymorphic

• wide QRS complex

• no P waves

• PR not measurable

• T wave often in opposite direction

Ventricular flutter

• heart rate 250-350

Vfib (ventricular fibrillation)

• heart rate >350 bpm

• polymorphic

• rhythm irregular/chaotic

• P wave not visible

• very fast and low amplitude

Torsades de Pointes

• all torsades are polymorphic VT

• not all poly VT is torsades

• prolonged QT interval

• pause dependant

• heart rate 200-300 bpm