In a patient, there is a prolonged PR interval noted on ECG graph which would be indicating to?

NORCET 5 mains

Medical & Surgical Nursing

Easy

Appeared in: NORCET 5 mains

Explanation

A prolonged PR interval signifies a delay in the electrical conduction from the atria to the ventricles through the AV node.
By definition, a first-degree atrioventricular (AV) block is characterized by a fixed and prolonged PR interval greater than 0.20 seconds (200 ms).
In first-degree AV block, every atrial impulse (P wave) is eventually conducted to the ventricles (QRS complex), but it takes longer than normal.

Option B: Atrial flutter is characterized by rapid, regular atrial depolarizations that create a 'sawtooth' pattern of flutter waves on the ECG, not a prolonged PR interval.
Option C: Atrial fibrillation involves chaotic, uncoordinated atrial activity, resulting in an absence of P waves and an irregularly irregular ventricular response. The PR interval cannot be measured.
Option D: Sinus bradycardia is a sinus rhythm with a rate of less than 60 beats per minute. The PR interval is typically within the normal range (0.12-0.20 seconds).

Visual 1: Infographic - A side-by-side comparison of ECG strips for normal sinus rhythm, first-degree AV block, atrial flutter, and atrial fibrillation, with the key features (PR interval, P waves, rhythm) highlighted for each.
Visual 2: Diagram - An illustration of the heart's electrical conduction system, showing the path from the SA node to the Purkinje fibers and highlighting the AV node as the site of the delay in first-degree AV block.

Clinical Relevance

Nursing practice connection: Use the key finding related to ECG interpretation of cardiac arrhythmias, specifically atrioventricular blocks to guide bedside assessment, documentation, and the next nursing action.
Nurses must be able to identify a first-degree AV block on an ECG because while often benign, it can be an early sign of underlying heart disease, electrolyte imbalances, or drug toxicity (e.g., from digoxin, beta-blockers, or calcium channel blockers).
Monitoring for progression is crucial. A first-degree AV block can advance to higher-degree blocks (second or third-degree), which are more serious and can cause hemodynamic instability.
What if? If the patient with a prolonged PR interval also had symptoms like dizziness or syncope and the ECG showed some P waves were not followed by a QRS complex (dropped beats), the diagnosis would change to a second or third-degree AV block, requiring more urgent intervention.

How to Approach the Question

First, identify the core finding in the question: a 'prolonged PR interval' on an ECG.
Second, recall the normal value for a PR interval, which is 0.12 to 0.20 seconds. 'Prolonged' means it is greater than 0.20 seconds.
Third, systematically evaluate each option based on its known ECG characteristics.
Option A (Atrioventricular block): A first-degree AV block is defined by a prolonged PR interval. This is a direct match.
Option B (Atrial flutter): This has sawtooth waves, not a prolonged PR.
Option C (Atrial fibrillation): This has no P waves and an irregular rhythm, so PR is not measurable.

Concept Tested & Keywords

Concept Tested: ECG interpretation of cardiac arrhythmias, specifically atrioventricular blocks.
Stem keywords: prolonged PR interval, ECG graph
Lead-in keywords: indicating to
Clinical cues: The key finding is a "prolonged PR interval," which is a specific measurement on an ECG.

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