Impulse FormationDisorders

Impulse FormationDisorders

Impulse ConductionImpulse ConductionDisordersDisorders

Impulse ConductionImpulse ConductionDisordersDisorders

• Sinus Tachycardia• Sinus Tachycardia• Atrial Tachycardia• Atrial Tachycardia

Classification Based on DisorderClassification Based on Disorder

• Premature Contractions• Premature Contractions

Tachyarrhythmia Tachyarrhythmia ClassificationsClassificationsTachyarrhythmia Tachyarrhythmia ClassificationsClassifications

• Accelerated Idio- Junctional Rhythm• Accelerated Idio- Junctional Rhythm• Accelerated Idioventricular Rhythm (AIVR)

• Accelerated Idioventricular Rhythm (AIVR)

• Atrial Flutter• Atrial Flutter• Atrial Fibrillation• Atrial Fibrillation• AVRT• AVRT• AVNRT• AVNRT

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 Ectopic Atrial Tachycardia and RhythmTachycardia and Rhythm

• Ectopic, discrete looking, unifocal P' waves with atrial rate <250/min Ectopic, discrete looking, unifocal P' waves with atrial rate <250/min (not to be confused with slow atrial flutter).(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 with Ectopic atrial rhythm is similar to ectopic atrial tachycardia, but with HR < 100 bpm 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 Atrial Flutter vs. Atrial FibrillationFibrillation

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

Accelerated idioventricular rhythm

Wide QRS Complex TachycardiaWide QRS Complex Tachycardia

• ·         QRS morphology in lead V1 for single premature funny ·         QRS morphology in lead V1 for single premature funny looking beats is often the looking beats is often the best cluebest clue to the origin, to the origin,

• Also consider a few additional morphology clues:Also consider a few additional morphology clues:• ·         Bizarre frontal-plane QRS axis (i.e. from +150 degrees to ·         Bizarre frontal-plane QRS axis (i.e. from +150 degrees to

-90 degrees or NW quadrant) suggests -90 degrees or NW quadrant) suggests ventricular tachycardiaventricular tachycardia• ·         QRS morphology similar to previously seen PVCs ·         QRS morphology similar to previously seen PVCs

suggests suggests ventricular tachycardiaventricular tachycardia• ·         If all the QRS complexes from V1 to V6 are in the same ·         If all the QRS complexes from V1 to V6 are in the same

direction (positive or negative), direction (positive or negative), ventricular tachycardiaventricular tachycardia is likely is likely• ·         Mostly or all negative QRS in V6 suggests ·         Mostly or all negative QRS in V6 suggests ventricular ventricular

tachycardiatachycardia• ·         Especially wide QRS complexes (>0.16s) suggests ·         Especially wide QRS complexes (>0.16s) suggests

ventricular tachycardiaventricular tachycardia• ·         Also consider the following Four-step Algorithm reported ·         Also consider the following Four-step Algorithm reported

by by Brugada et al, Circulation 1991;83:1649:Brugada et al, Circulation 1991;83:1649:

The classic Brugada pattern (type 1) consists of ST-segment elevations that descend and have an upward T-wave inversion ("coved type") in leads V1 through V3Types 2 and 3 have "saddleback" ST-T waves, with descending ST segments and an upright T wave; in type 2, the T wave is also upright or biphasic A slight prolongation of the QT interval in Brugada-type ECG may be observed in the right precordial leads, secondary to the prolongation of the action potential duration in the right ventricular epicardium The Brugada ECG patterns can be differentiated from typical right bundle-branch block patterns by the absence of widened S waves.