Ode to a Node:
Have a heart, and have no fear,
The SA node is over here.
Beating at a constant rate,
60-100 is really great.
The AV node can make a show
If SA node has gone too slow.
40-60 is not too bad,
If it’s all you’ve got, you will be glad.
Should the whole thing drop its speed,
His and bundle branches will take the lead.
And that, my friend is the whole and part,
Of the conduction system of your heart.
Pitiful and Corney, to say the least. Taken from the book “Flip and See ECG.”