Third degree AV block: Difference between revisions
Ostermayer (talk | contribs) |
|||
| (3 intermediate revisions by 3 users not shown) | |||
| Line 1: | Line 1: | ||
==Background== | ==Background== | ||
[[File:Rhythm strip showing third degree heart block.jpg|thumb|Rhythm strip showing third degree AV block. Note that the P waves are not related to the QRS complexes (PP interval and QRS interval both constant), demonstrating that the atria are electrically disconnected from the ventricles | [[File:Rhythm strip showing third degree heart block.jpg|thumb|Rhythm strip showing third degree AV block. Note that the P waves are not related to the QRS complexes (PP interval and QRS interval both constant), demonstrating that the atria are electrically disconnected from the ventricles.]] | ||
*Also known as complete heart block | *Also known as complete heart block | ||
*No conduction through the AV node, causing the atria and ventricles beat completely independently from each other | *No conduction through the AV node, causing the atria and ventricles beat completely independently from each other | ||
| Line 8: | Line 8: | ||
*Congenital | *Congenital | ||
*Acquired | *Acquired | ||
**Ischemia | **[[Myocardial ischemia|Ischemia]] | ||
**Increased vagal tone | **Increased vagal tone | ||
**[[Hypothyroidism]] | **[[Hypothyroidism]] | ||
**[[Hyperkalemia]] | **[[Hyperkalemia]] | ||
**Drugs | **[[Toxicology (Main)|Drugs]] | ||
**Structural heart disease | **Structural heart disease | ||
| Line 34: | Line 34: | ||
==Management== | ==Management== | ||
{{Heart block management}} | |||
==Disposition== | ==Disposition== | ||
Latest revision as of 15:10, 21 December 2020
Background
- Also known as complete heart block
- No conduction through the AV node, causing the atria and ventricles beat completely independently from each other
- The ventricular beat is an escape rhythm anywhere from the AV node to the bundle-branches (normally slow, varying from 35 to 45 beats per minute)
Causes
- Congenital
- Acquired
- Ischemia
- Increased vagal tone
- Hypothyroidism
- Hyperkalemia
- Drugs
- Structural heart disease
Clinical Features
Differential Diagnosis
AV blocks
- First degree AV block
- Second degree
- Third degree AV block
- AV dissociation without complete heart block
Evaluation
- No atrial impulses are conducted
- P waves normal and regular P-P intervals unrelated to slower regular R-R intervals
- QRS narrow if block above bundle of His
- QRS wide if block below bundle of His
- PR variable
- Differentiate from AV dissociation without complete heart block
Management
- If symptomatic, standard ACLS guidelines for symptomatic bradycardia to include[1]
- Atropine 0.5mg IV q3-5min PRN total dose of 3mg
- Transcutaneous pacing, followed by transvenous pacing
- Dopamine IV consider for low BP 3mcg/kg/minute titrate up to 20 mcg/kg/minute
- Dobutamine IV consider for heart failure at 5mcg/kg/minute titrate up to 20mcg/kg/minute if needed for HR and BP augmentation
- Treat underlying etiology
- Avoid AV nodal blocking agents (e.g. β-blockers)
Disposition
- Admission for pacemaker placement
See Also
References
- ↑ Sovari AA et al. Second-Degree Atrioventricular Block Treatment & Management. eMedicine. Apr 28, 2014. http://emedicine.medscape.com/article/161919-treatment#showall.