Final answer:
A nurse would expect an abnormally long PR interval when reading a client's ECG who has a first-degree AV block. This condition, which does not usually affect heart rate or cause symptoms, indicates a delay in the conduction between the SA and AV nodes in the heart's electrical system. Despite this delay, all impulses still manage to reach the AV node.
Step-by-step explanation:
In a client with a first-degree Atrioventricular (AV) block, a nurse would expect to find an abnormally long PR interval when analyzing their cardiac rhythm. This is because a first-degree AV block denotes a delay in conduction between the SA and AV nodes of the heart. An Electrocardiogram (ECG) acts as a critical tool in diagnosing this condition, portraying an extended space between the P wave, which signals atrial contraction, and the QRS complex, signifying ventricular contraction.
It's important to note that despite this delay, each impulse from the SA node does make it to the AV node - a characteristic that differentiates first-degree AV block from more severe second- and third-degree blocks, where some or all impulses fail to reach the AV node.
The heart rate in a first-degree AV block
A key distinction to make is that a first-degree AV block does not generally affect the heart rate (pulse) or lead to symptoms. However, it does indicate a disturbance in the heart's electrical conduction system, and this can potentially progress into a more severe form of AV block.
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