First Degree AV Block

First Degree AV Block

Rate	Variable
P wave	Normal
QRS	Normal
Conduction	Impulse originates in the SA node but has prolonged conduction in the AV junction; P-R interval is > 0.20 seconds.
Rhythm	Regular

This is the most common conduction disturbance. It occurs in both healthy and diseased hearts.

First degree AV block can be due to:

inferior MI,

digitalis toxicity

hyperkalemia

increased vagal tone

acute rheumatic fever

myocarditis.

Interventions include treating the underlying cause and observing for progression to a more advanced AV block.

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In first degree AV block, the P-R interval is: