1) Bradyarrhythmias include sinus bradycardia, junctional rhythm, sinoatrial block, and atrioventricular block which can be first, second, or third degree. 2) Tachyarrhythmias include ventricular tachycardia, ventricular fibrillation, atrial fibrillation, AV nodal reentrant tachycardia, and atrial tachycardia. Narrow complex tachycardias require analyzing the P waves and PR and RP intervals to determine the mechanism. 3) Different arrhythmias are caused by abnormalities in impulse conduction through the heart or abnormal automaticity in the sinoatrial node or elsewhere. Diagnosis requires interpreting the rhythm on

2. Dysrrhythmia
Dr. Ahmed Taha Hussein
Assistant lecturer cardiology and
electrophysiology
Faculty of medicine
Zagazig university
2

3. Mechanisms of Arrhythmogenesis

4. BRADYARRYTHMIA
The heart runs down !!!!

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

6. Impulse Conduction & the ECG
Sinoatrial node
AV node
Bundle of His
Bundle Branches

7. Sinus Bradycardia

8. Junctional Rhythm

9. 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

10. AV Block
• First Degree AV Block
• Second Degree AV Block
• Third Degree AV Block

11. 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.

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

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

14. Mobitz type 1 (Wenckebach Phenomenon)

15. •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.

16. 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;

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

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

19. Ventricular Arrhythmias
• Ventricular Tachycardia
• Ventricular Fibrillation

20. Rhythm #8
• Rate? 160 bpm
• Regularity? regular
• P waves? none
• PR interval? none
• QRS duration? wide (> 0.12 sec)
Interpretation? Ventricular Tachycardia

21. Ventricular Tachycardia
• Deviation from NSR
– Impulse is originating in the ventricles (no P
waves, wide QRS).

22. Rhythm #9
• Rate? none
• Regularity? irregularly irreg.
• P waves? none
• PR interval? none
• QRS duration? wide, if recognizable
Interpretation? Ventricular Fibrillation

23. Ventricular Fibrillation
• Deviation from NSR
– Completely abnormal.

24. 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

25. Looking at the PR-RP intervals
• Long RP tachycardia
– Sinus tachycardia
– Atrial tachycardia
– Some AVRTs
– Junctional tachycardia
PR RP
– Aytypical AVNRT
RP PR
• Short RP tachycardia
– Typical AVNRT
RP<PR RP>PR
(Short RP) (Long RP)
– Most AVRTs
– Atach with long PR interval

26. 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)

27. “pseudo-R’”

28. 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

30. 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

33. Increased/Abnormal Automaticity
Sinus tachycardia
Ectopic atrial tachycardia
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Junctional tachycardia