ecg 3

VVIVVI

Premature BeatsPremature BeatsPremature Atrial Contraction (PAC) Premature Atrial Contraction (PAC)

•Origin: Atrium (outside the Sinus Node)

•Mechanism: Abnormal Automaticity

•Characteristics: An abnormal P-wave occurring

earlier than expected, followed

by compensatory pause

•Origin: Atrium (outside the Sinus Node)


•Characteristics: An abnormal P-wave occurring

earlier than expected, followed

by compensatory pause

Premature Junctional ContractionPremature Junctional Contraction

•Origin: AV Node Junction


•Characteristics:A normally conducted complex with

an absent p-wave, followed by a

compensatory pause

•Origin: AV Node Junction


•Characteristics:A normally conducted complex with

an absent p-wave, followed by a

compensatory pause

Premature BeatsPremature BeatsPremature BeatsPremature Beats

Premature Ventricular Contractions (PVCs)

Premature Ventricular Contractions (PVCs)

•Origin: Ventricles


•Characteristics: A broad complex occurring earlier

than expected, followed by a compensatory pause

•Origin: Ventricles


•Characteristics: A broad complex occurring earlier

than expected, followed by a compensatory pause

Premature BeatsPremature BeatsPremature BeatsPremature Beats

•Origin: Varies within the Ventricle


•Characteristics:Each premature beat changes axis;

implies a different focus origin for each beat

•Origin: Varies within the Ventricle


•Characteristics:Each premature beat changes axis;

implies a different focus origin for each beat

Multifocal PVCMultifocal PVC

ABERRANT VENTRICULAR ABERRANT VENTRICULAR CONDUCTIONCONDUCTION

A term that describes temporary alteration of QRS A term that describes temporary alteration of QRS morphology under conditions where a normal QRS morphology under conditions where a normal QRS might be expected. The common types are:might be expected. The common types are:

1. Through normal conduction pathways:1. Through normal conduction pathways: Cycle-length dependent (Ashman phenomenon)Cycle-length dependent (Ashman phenomenon) Rate-dependent tachycardia or bradycardiaRate-dependent tachycardia or bradycardia

2. Through accessory pathways (e.g., Kent 2. Through accessory pathways (e.g., Kent bundle)bundle)

Ashman PhenomenonAshman Phenomenon

““Las Vegas” type betting Las Vegas” type betting odds of making the right odds of making the right

diagnosisdiagnosis

1) fat little initial r-wave,1) fat little initial r-wave, 2) notch or slur in the 2) notch or slur in the

downstroke of the S downstroke of the S wave, wave,

3) a 0.06 sec or more 3) a 0.06 sec or more delay from the delay from the beginning of the QRS to beginning of the QRS to the nadir of the S-wave.the nadir of the S-wave.

•1&2-90% Aberrant Conduction•3- 50-50%- not helpful•4 -100:1- Ventricular Ectopy•5 - m/p Vntricular with two exceptions :

• Some people with normal ECG’s do not have an initial little r-wave in the QRS of lead V1. If RBBB occurs in such a person the QRS morphology in V1 will be a qR instead of an rsR’.• In a person with a previous anterior or anteroseptal infarction the V1 QRS often has a QS morphology, and RBBB in such a person will also have a qR pattern.

"Cherchez le P sur le T"

a “critical rate” -a “tired” a “critical rate” -a “tired” but not “dead” bundle but not “dead” bundle

branchbranch

Don’t be fooled by first Don’t be fooled by first impressions. impressions. Not all FLBs Not all FLBs

are ventricular in originare ventricular in origin!!

Based on originBased on origin

• Sinus Tachycardia• Atrial Tachycardia•AVRT•AVNRT• Atrial Flutter• Atrial Fibrillation

• Sinus Tachycardia• Atrial Tachycardia•AVRT•AVNRT• Atrial Flutter• Atrial Fibrillation

Tachyarrhythmia Tachyarrhythmia ClassificationsClassifications

• Ventricular Fibrillation (VF)• Ventricular Fibrillation (VF)

• Ventricular Tachycardia (VT)• Ventricular Tachycardia (VT)

Sinus TachycardiaSinus Tachycardia

•Origin: Sinus Node•Rate: 100-180 BPM•Mechanism: Abnormal (Hyper)

Automaticity

Ectopic Atrial Tachycardia Ectopic Atrial Tachycardia and Rhythmand Rhythm

Ectopic, discrete looking, unifocal P' waves with atrial rate Ectopic, discrete looking, unifocal P' waves with atrial rate <250/min (not to be confused with slow atrial flutter).<250/min (not to be confused with slow atrial flutter).

Ectopic P' waves usually precede QRS complexes with P'R interval Ectopic P' waves usually precede QRS complexes with P'R interval < RP' interval (i.e., not to be confused with paroxysmal < RP' interval (i.e., not to be confused with paroxysmal supraventricular tachycardia with retrograde P waves shortly after supraventricular tachycardia with retrograde P waves shortly after the QRS complexes).the QRS complexes).

The above ECG shows sinus rhythm, a PVC, and the onset of ectopic The above ECG shows sinus rhythm, a PVC, and the onset of ectopic atrial tachycardia (note different P wave morphology)atrial tachycardia (note different P wave morphology)

Ventricular response may be 1:1 (as above ECG) or with varying Ventricular response may be 1:1 (as above ECG) or with varying degrees of AV block (especially in the setting of digitalis toxicity.degrees of AV block (especially in the setting of digitalis toxicity.

Ectopic atrial rhythm is similar to ectopic atrial tachycardia, but Ectopic atrial rhythm is similar to ectopic atrial tachycardia, but with HR < 100 bpm with HR < 100 bpm

Atrial FlutterAtrial Flutter

•Origin: Right & Left Atrium

•Mechanism: Reentry

•Characteristics: Rapid, regular p-waves

•Origin: Right & Left Atrium

•Mechanism: Reentry

•Characteristics: Rapid, regular p-waves

*Animation

Atrial Fibrillation (AF)Atrial Fibrillation (AF)

•Origin: Right and/or left atrium

•Mechanism: Multiple wavelets of reentry

•Rate 400 BPM

•Characteristics: Random, chaotic rhythm;

atria quiver; associated withirregular ventricular rhythm

•Origin: Right and/or left atrium

•Mechanism: Multiple wavelets of reentry

•Rate 400 BPM

•Characteristics: Random, chaotic rhythm;

atria quiver; associated withirregular ventricular rhythm

*Animation

Atrial Fibrillation (AF)Atrial Fibrillation (AF)

Multifocal FiringMultifocal FiringMultifocal FiringMultifocal FiringOther AF MechanismsOther AF Mechanisms

•Mechanism: Abnormal Automaticity (multi-sites)

•Characteristics:Many depolarization waves;

activation occurs asynchronously;not in rhythm with sinus node

•Mechanism: Abnormal Automaticity (multi-sites)

•Characteristics:Many depolarization waves;

activation occurs asynchronously;not in rhythm with sinus node

Atrial Flutter vs. Atrial Flutter vs. Atrial FibrillationAtrial Fibrillation

Atrial Flutter Atrial Flutter

Summary of Disease CharacteristicsSummary of Disease Characteristics

Underlying Underlying MechanismMechanismUnderlying Underlying MechanismMechanism

PatternPatternPatternPattern

Atrial RateAtrial Rate

Ventricular Ventricular RateRate

RhythmRhythm

Atrial RateAtrial Rate

Ventricular Ventricular RateRate

RhythmRhythm

Atrial FibrillationAtrial Fibrillation

Multiple wavelet reentryMultiple wavelet reentry Multiple/single focusMultiple/single focus

firingfiring

Multiple wavelet reentryMultiple wavelet reentry Multiple/single focusMultiple/single focus

firingfiring

Wavy baselineWavy baseline Wavy baselineWavy baseline

• 400400 BPMBPM

• Varies w/conductionVaries w/conduction

• Grossly IrregularGrossly Irregular

• 400400 BPMBPM

• Varies w/conductionVaries w/conduction

• Grossly IrregularGrossly Irregular

Reentry via macroReentry via macro

reentrant circuitreentrant circuit

Reentry via macroReentry via macro

reentrant circuitreentrant circuit

Saw tooth baselineSaw tooth baseline Saw tooth baselineSaw tooth baseline

250250 to 400 BPMto 400 BPM

Varies w/conductionVaries w/conduction

Usually regularUsually regular

250250 to 400 BPMto 400 BPM

Varies w/conductionVaries w/conduction

Usually regularUsually regular

F/S AVNRTF/S AVNRT

WPWWPW

ecg 3

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