Atrioventricular node and His bundle
Territory
The AV node sits in the triangle of Koch in the low right atrium; the bundle of His penetrates the fibrous skeleton and divides on the membranous septum. The node and proximal bundle are fed by the AV nodal artery, the distal bundle and bundle branches by the first septal perforator, giving the bundle a dual supply.
Traced from the start
Detail
- Supplied by
- AV nodal artery (node, proximal bundle) plus first septal perforator (distal bundle, branches)
- Escape rhythm if blocked
- Nodal block: junctional 40 to 60/min, narrow QRS; infranodal block: ventricular 20 to 40/min, wide QRS
When it goes wrong
Complete heart block complicating inferior MI
Block within the node: narrow escape, haemodynamically tolerated, transient, atropine works
Complete heart block complicating anterior MI
Block below the node from septal necrosis: wide slow escape, poor prognosis, immediate pacing
Practise this structure
1 question in the bank tagged Atrioventricular Node.