Simple ECG lecture about sinus arrest, sinoatrial exit block, AV block and escape rhythms. Slideshow was made with an audience of medical professionals in mind.
ECG Lecture: Sinus arrest, sinoatrial exit block, AV block and escape rhythms
1. Sinus arrest, Sinoatrial exit block,
AV blocks, Escape Rhythms
Dr. Michael-Joseph F. Agbayani, MD FPCP FPCC
@HeartRhythmMD
2. Images used are mine or under a creative commons
license or public domain.
5. SA node: 60 to 100
SA node: 60 to 100
bpm
bpm
AV Junction: 40 to
AV Junction: 40 to
60 bpm
60 bpm
Ventricle: <40 bpm
Ventricle: <40 bpm
8. Sinoatrial Exit Block
• Sinus node still firing
• Impulse fails to conduct beyond SA node
• Degrees
– First degree SA exit block
– Second degree SA exit block (Type 1 and type 2)
– Third degree SA exit block
9. First degree sinoatrial block
• First degree
– Delay in conduction of sinus impulse
– Not evident in a surface ECG
10. Second degree sinoatrial block
• Intermittent failure of the sinus impulse to
exit the node
• Type 1
– Progressive delay in sinus impulse resulting in
non-conducted impulse
– Group beating (Wenckebach periodicity)
12. Second-degree sinoatrial block
• Type 2
– Failed conduction of sinus impulse without
progressive prolongation of sinoatrial conduction
time
– Pause is a multiple of baseline P-P interval
14. Third-degree sinoatrial block
• None of the sinus node impulses are able to
exit the node
• Absence of p waves
• Indistinguishable from sinus arrest
15. Sinus Pause / Sinus Arrest
• Sinus node doesn’t fire
• P-P interval of the pause not a multiple of the
baseline P-P interval
• Usually said to be abnormal if > 3 seconds
18. First degree AV block
•
•
•
•
PR interval is > 200 ms and is constant
Each p wave is followed by QRS complex
Marked first degree is >300 ms
May be symptomatic
20. Second Degree AV Block
•
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One non-conducted p wave
Mobitz Type 1 (Wenckebach Block)
Mobitz Type 2
2:1 AV block
21. Mobitz Type 1 (Wenckebach)
• Gradual prolongation of PR interval until nonconducted p wave
• RP-PR reciprocity
• Lengthening of the PR interval at progressively
shorter decrements
• Progressively shorter R-R intervals and group beating
• Shortening back to baseline PR interval after the
blocked cycle
24. Mobitz Type 2
• No change in PR before non-conducted P
wave
• Usually associated with His-Purkinje disease
28. 2:1 AV block
• Second degree AV block
• Every other beat is conducted
• PR interval in conducted beats is usually
constant
29. 2:1 AV block
• Classifying into Mobitz Type 1 or type 2 is
discouraged
• Clues to level of block
– Narrow vs wide complex
– Long or short PRs in conducted beats
– PR and RP relationship
– Presence of Mobitz Type 1 block
– Response to Atropine or exercise
32. High Grade AV Block
• At least 2 consecutive non-conducted P waves
(3:1 AV Block)
• Also called “advanced second-degree heart
block”
• Look at the PR interval of conducted beats:
should be constant
34. 3rd Degree or Complete Heart Block
• None of the P waves are conducted
• P waves and QRS complexes occur
independently of each other
• R-R intervals are usually regular (junctional or
ventricular escape rhythm)
35. SA node: 60 to 100
SA node: 60 to 100
bpm
bpm
AV Junction: 40 to
AV Junction: 40 to
60 bpm
60 bpm
Ventricle: <40 bpm
Ventricle: <40 bpm
37. • R-R intervals are usually regular (escape
rhythm)
• “PR” intervals are not constant / no pattern
• Escape rhythm can be junctional or ventricular
38. Escape Rhythms
• Atrial escape rhythm (<60 bpm)
– P wave morphology abnormal
• Junctional rhythm (40 to 60 bpm)
– Narrow QRS
– Retrograde P waves shortly before or after QRS, if
any
• Ventricular rhythm (<40 bpm)
– Wide, “bizarre” QRS complexes
40. SA node: 60 to 100
SA node: 60 to 100
bpm
bpm
AV Junction: 40 to
AV Junction: 40 to
60 bpm
60 bpm
Ventricle: <40 bpm
Ventricle: <40 bpm
44. Images
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Heart image with conduction system: Public Domain image from Gray’s Anatomy
QRS complex: Public Domain image from Wikipedia user
http://en.wikipedia.org/wiki/User:Agateller
Road Block sign: http://en.wikipedia.org/wiki/File:Road_block.jpg
Traffic: http://en.wikipedia.org/wiki/File:Traffic_jam_on_Phu_Nhuan_district.JPG
Sinoartial exit block: http://commons.wikimedia.org/wiki/User:Jer5150
First degree AV block: http://www.flickr.com/photos/popfossa/
Second Degree AV block Mobitz Type 1:
http://commons.wikimedia.org/wiki/User:Jer5150
Mobitz type 2 and 2:1: http://commons.wikimedia.org/wiki/User:Jer5150
Complete heart block: http://commons.wikimedia.org/wiki/User:Jer5150
Complete heart block strip: http://en.wikipedia.org/wiki/User:MoodyGroove
Junctional rhythm: http://www.flickr.com/photos/nottinghamvets/
45. Images
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Sinus pause: http://commons.wikimedia.org/wiki/User:Stevenfruitsmaak
Mobitz Type 1 with escape: Michael Rosengarten BEng, MD.McGill
(ecgpedia.org)
SCT with Pause: Michael Rosengarten BEng, MD.McGill (ecgpedia.org)
Mobitz type 1 and type 2 strips: Munther Homoud, M.D.
(http://ocw.tufts.edu/)
Mobitz Type II: http://lifeinthefastlane.com/author/edward-burns/
High Grade AV block: http://lifeinthefastlane.com/author/edward-burns/
Ventricular Escape rhythm: http://lifeinthefastlane.com/author/edwardburns/
Fixed ratio blocks: http://lifeinthefastlane.com/author/edward-burns/
46. SA exit block, Sinus Arrest, AV Blocks and Escape Rhythms
ECG EXERCISE
56. Images
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First Degree AV block: http://www.flickr.com/photos/popfossa/
4:1 AV block: http://www.flickr.com/photos/popfossa/
Mobitz type 1: http://www.flickr.com/photos/popfossa/
First Degree AV block: http://www.flickr.com/photos/popfossa/
Type II Sinoatrial exit block: http://lifeinthefastlane.com/author/edward-burns/
Mobitz type 1: http://lifeinthefastlane.com/author/edward-burns/
Complete Heart Block; http://lifeinthefastlane.com/author/edward-burns/
Sinus arrest: http://lifeinthefastlane.com/author/edward-burns/
High grade Av block and Mobitz Type 2:
http://lifeinthefastlane.com/author/edward-burns/
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