View source for Third degree AV block

==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.]]
*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
**[[Myocardial ischemia|Ischemia]]
**Increased vagal tone
**[[Hypothyroidism]]
**[[Hyperkalemia]]
**[[Toxicology (Main)|Drugs]]
**Structural heart disease

==Clinical Features==
*[[Dizziness]]
*[[Syncope]]
*[[Hypotension]]

==Differential Diagnosis==
{{AV block types}}

==Evaluation==
[[File:Rhythm 3rdAVblock.jpg|thumbnail]]
*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
[[File:AVD without CHB.png|thumbnail|AVD without CHB, courtesy of public access Amal Mattu EKG videos]]

==Management==
{{Heart block management}}

==Disposition==
*Admission for [[Pacemaker (Basics)|pacemaker]] placement

==See Also==
*[[ECG (Main)]]

==References==
<references/>

[[Category:Cardiology]]