ECG A: AV blocks

ECG cases alphabet

1. ECG A: AV blocks
Domina Petric, MD

2. AV block first degree
Burns E. First Degree Heart Block (April 16, 2017). Retrieved from
https://lifeinthefastlane.com/ecg-library/basics/first-degree-heart-block/

3. •PR interval>200ms.
•Severefirst degree block is when thePR
interval is more than300ms.
AV block first degree

4. •increased vagal tone
•athletic training
•inferior MI
•mitral valve surgery
•myocarditis(Lyme disease)
•electrolyte disturbances (hyperkalaemia)
•AV nodal blocking drugs (beta-blockers,calcium
channelblockers,digoxin, amiodarone)
•normal variant
Causes

5. AV block second degree, Mobitz I
(Wenckebach phenomenon)
Burns E. AV Block: 2nd degree, Mobitz I (May 24, 2018). Retrieved
from https://lifeinthefastlane.com/ecg-library/basics/wenckebach/

6. Wenckebach phenomenon

7. Wenckebach phenomenon
The Wenckebachpattern tends to repeat in
P:QRS groups with ratios of 3:2, 4:3 or 5:4.

8. Malfunctioning AV node cells
tend to progressively fatigue
until they fail to conduct an
impulse.
This is different to cells of the
His-Purkinje system which tend
to fail suddenly and
unexpectedly (MobitzII block).
Mechanism

9. •beta-blockers,calcium channel
blockers,digoxin, amiodarone
•increased vagal tone (athletes)
•inferior MI
•myocarditis
•following cardiac surgery (mitral valve
repair, Tetralogy of Fallot repair)
Causes

10. Symptomatic
patients usually
respond to atropine.
Treatment

11. AV block second degree: Mobitz II
Burns E. AV Block: 2nd degree, Mobitz II(May 24, 2018). Retrived from
https://lifeinthefastlane.com/ecg-library/basics/mobitz-2/

12. There are intermittent
non-conducted P
waveswithoutprogressive
prolongation of the PR
interval.
Mobitz II

13. Mobitz II
There is no prolongation of the PR interval.

14. MobitzII is more likely to be
duetostructuraldamage to
the conducting system
(infarction, fibrosis,
necrosis).
Mobitz II

15. In around 75% of cases, the conduction block
is locateddistal to the Bundle of His,
producingbroad QRS complexes.
In the remaining 25% of cases, the conduction
block is located within the His Bundle itself,
producing narrow QRS complexes.
Mobitz II

16. •anterior MI
•idiopathic fibrosis of the conducting system (Lenegre’s or
Lev’s disease)
•cardiac surgery (mitral valve repair)
•inflammatory conditions (rheumatic fever, myocarditis,
Lyme disease)
•autoimmune (SLE, systemic sclerosis)
•infiltrative myocardial disease (amyloidosis,
haemochromatosis, sarcoidosis)
•hyperkalaemia
•beta-blockers, calcium channel blockers,digoxin,
amiodarone
Causes

17. Immediateadmission for
cardiac monitoring, backup
temporary pacing and
ultimately insertion of a
permanent pacemaker.
Treatment

18. Second
degree heart
blockwith
P:QRS ratio of
3:1 or higher
is a high-grade
AV block.
There isan
extremely
slow
ventricular
rate.
There is still
some
relationship
between the
P waves and
the QRS
complexes.
High-grade AV block of second degree

19. AV block third degree (complete heart block)
Burns E. AV block: 3rd degree (April 16, 2017). Retrieved from
https://lifeinthefastlane.com/ecg-library/basics/complete-heart-block/

20. Complete heart block

21. Complete heart block
Complete heart block is the end point of
either MobitzI or MobitzII AV block.

22. Inferior MI
AV-nodal
blocking
drugs:
calcium-
channel
blockers, beta
blockers,
digoxin
Idiopathic
degeneration
of the
conducting
system
(Lenegre’s or
Lev’s disease)
Causes

23. Urgentadmission forcardiac
monitoring, backup temporary
pacing and insertion of a
permanent pacemaker.
Treatment

24. Lifeinthefastlane.com
Literature