Dysrrhythmia

Dr. Ahmed Taha Hussein Assistant lecturer cardiology and

electrophysiology Faculty of medicine Zagazig university

2

Mechanisms of Arrhythmogenesis

BRADYARRYTHMIA

The heart runs down !!!!

Classification• Sinus Bradycardia• Junctional Rhythm• Sino Atrial Block• Atrioventricular block

Impulse Conduction & the ECGSinoatrial node

AV node

Bundle of His

Bundle Branches

Sinus Bradycardia

Junctional Rhythm

SA Block• Sinus impulses is blocked within the SA junction• Between SA node and surrounding myocardium• Abscent of complete Cardiac cycle• Occures irregularly and unpredictably• Present :Young athletes, Digitalis, Hypokalemia, Sick

Sinus Syndrome

AV Block

• First Degree AV Block• Second Degree AV Block• Third Degree AV Block

First Degree AV Block• Delay in the conduction through the conducting system• Prolong P-R interval• All P waves are followed by QRS• Associated with : AC Rheumati Carditis, Digitalis, Beta

Blocker, excessive vagal tone, ischemia, intrinsic disease in the AV junction or bundle branch system.

Second Degree AV Block

• Intermittent failure of AV conduction • Impulse blocked by AV node• Types:• Mobitz type 1 (Wenckebach Phenomenon)• Mobitz type 2

The 3 rules of "classic AV Wenckebach" 1. Decreasing RR intervals until pause; 2. Pause is less than preceding 2 RR intervals3. RR interval after the pause is greater than RR prior to pause.

Mobitz type 1 (Wenckebach Phenomenon)

Mobitz type 1 (Wenckebach Phenomenon)

•Mobitz type 2

•Usually a sign of bilateral bundle branch disease.•One of the branches should be completely blocked;•most likely blocked in the right bundle •P waves may blocked somewhere in the AV junction, the His bundle.

Third Degree Heart Block

•CHB evidenced by the AV dissociation•A junctional escape rhythm at 45 bpm. •The PP intervals vary because of ventriculophasic sinus arrhythmia;

Third Degree Heart Block

3rd degree AV block with a left ventricular escape rhythm, 'B' the right ventricular pacemaker rhythm is shown.

Tachyarrythmia

also known as things that go crump in the night!)

Ventricular ArrhythmiasVentricular Arrhythmias• Ventricular TachycardiaVentricular Tachycardia

• Ventricular FibrillationVentricular Fibrillation

Rhythm #8Rhythm #8

160 bpm• Rate?• Regularity? regular

none

wide (> 0.12 sec)

• P waves?• PR interval? none• QRS duration?

Interpretation? Ventricular Tachycardia

Ventricular TachycardiaVentricular Tachycardia

• Deviation from NSRDeviation from NSR– Impulse is originating in the ventricles (no P Impulse is originating in the ventricles (no P

waves, wide QRS).waves, wide QRS).

Rhythm #9Rhythm #9

none• Rate?• Regularity? irregularly irreg.

none

wide, if recognizable

• P waves?• PR interval? none• QRS duration?

Interpretation? Ventricular Fibrillation

Ventricular FibrillationVentricular Fibrillation

• Deviation from NSRDeviation from NSR– Completely abnormal.Completely abnormal.

Narrow Complex Tachycardia

• Differential diagnoses– Sinus tachycardia– Atrial tachycardia– AV nodal reentrant tachycardia– Orthodromic AV reciprocating tachycardia (CMT)– Atrial fibrillation/flutter– Unusual VTs

• Look for P-waves • Let the PR-RP relationship help you

RP

PR

Looking at the PR-RP intervals

• Long RP tachycardia– Sinus tachycardia– Atrial tachycardia– Some AVRTs– Junctional tachycardia– Aytypical AVNRT

• Short RP tachycardia– Typical AVNRT– Most AVRTs– Atach with long PR interval

RP

PR

RP<PR (Short RP)

RP>PR (Long RP)

AV Nodal Reentrant Tachycardia (AVNRT)

• Most common reentrant SVT

• May achieve rates >200 bpm

• Look for the psuedo-R’ in V1 or NO P wave AT ALL!

• AV node dependent!• Most common type (>90%)

is the slow-fast variety (typical)

“pseudo-R’”

Atrial tachycardia• Can be an incessant rhythm• Rate: usually <220 bpm• Does not need the AV node for

perpetuation• Adenosine response:– Transient AV block WITHOUT termination– Transient AV block WITH termination (40%)

• Use your knowledge of the AV node to make the diagnosis

Atrioventricular Reciprocating Tachycardia (AVRT)

• Can be orthodromic (most common) or antidromic (very uncommon)

• Needs AV node to perpetuate rhythm

• Always associated with an AV bypass tract

• May mimic AVNRT and atrial tachycardia

• Can be short or long RP

Increased/Abnormal Automaticity

Sinus tachycardia

Junctional tachycardia

Ectopic atrial tachycardia

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