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Steps to Reading EKG Rhythms

Deciphering EKGs can pose a challenge, particularly for those lacking formal training. However, it has become a routine task for nurses and clinicians in their daily practice. Electrocardiograms depict waves that mirror the depolarization and contraction of different heart segments.

The EKG display exhibits multiple waves, typically denoted as PQRST. The P-wave represents a trial depolarization and contraction, the QRS-wave indicates ventricular contraction, and the T-wave illustrates ventricular relaxation and repolarization.

For interpreting EKGs, a systematic five-step approach can be employed to evaluate a patient's cardiac status:

1. Calculate sinus rate

To calculate the sinus rate, tally the number of R peaks and multiply the count by ten. This calculation provides the beats per minute, considering that the monitor typically shows only a brief snapshot of electrical activity.

In interpreting these findings, it's crucial to understand that the normal sinus rhythm (NSR) typically results in 60–100 beats per minute. A rate slower than 60 bpm is termed normal sinus bradycardia, while a rate exceeding 100 bpm is categorized as normal sinus tachycardia.

2. Assess the rhythm

The rhythm should display consistent and evenly spaced intervals between peaks. When there are irregular gaps between pulses, it may indicate an arrhythmia in the patient. In such cases, it's essential to thoroughly examine all waves, paying close attention to the presence and regularity of both the P and QRS waves.

3. Assess the P-wave

Evaluate whether the P-wave appears typical, which becomes more intuitive with experience. Deviations in the P-wave may indicate issues with atrial depolarization. Normally, the duration of the P-wave should be less than 0.12 seconds.

4. Assess PR interval

The PR interval encompasses the P-wave and the PR segment, measured from the start of the P-wave to onset of the QRS complex. A typical PR interval spans less than five small boxes on the EKG paper, corresponding to 0.12-0.20 seconds. Shorter PR intervals occur with higher heart rates, indicating a sympathetic-driven enhancement of AV nodal conduction. A shortened PR interval might indicate Wolff-Parkinson-White syndrome, while a prolonged PR interval could signify AV node blockage.

5. Assess QRS complex

This denotes the duration of ventricular depolarization and contraction. The QRS duration typically ranges from 0.06 to 0.10 seconds and remains unaffected by heart rate variations. Elevated voltage levels may suggest hypertrophy of the left or right ventricle.

EKG NCLEX questions from Naxlex NCLEX test bank

1. During an EKG assessment, the nurse observes a shortened PR interval. What condition should the nurse be particularly concerned about?

A) Atrial flutter

B) Sinus bradycardia

C) Ventricular fibrillation

D) Wolff-Parkinson-White syndrome

Answer: D) Wolff-Parkinson-White syndrome

Explanation: A shortened PR interval may indicate an accessory pathway between the atria and ventricles, characteristic of Wolff-Parkinson-White syndrome. This pathway bypasses the normal AV node, resulting in a shortened PR interval and a characteristic delta wave. Options A, B, and C are associated with different EKG findings and clinical conditions.

2. A patient's heart rhythm exhibits a regular pattern with a heart rate of 40 beats per minute and a narrow QRS complex. Which of these conditions could be consistent with this presentation? (Select all that apply)

A) Sinus bradycardia

B) Third-degree heart block

C) Ventricular tachycardia

D) Hypothermia

Correct answers: A) Sinus bradycardia and D) Hypothermia

Explanation: Sinus bradycardia is characterized by a slow heart rate (less than 60 beats per minute) with regular P waves preceding each QRS complex. Hypothermia can also cause bradycardia and a slow heart rate. Third-degree heart block typically presents with an irregular rhythm, and ventricular tachycardia is associated with a fast heart rate and widened QRS complexes.

3. A patient's EKG reveals a PR interval of 0.14 seconds and a widened QRS complex. Which of the following conditions could explain these findings? (Select all that apply)

A) Atrial fibrillation

B) Right bundle branch block

C) Hyperkalemia

D) First-degree heart block

Correct answers: B) Right bundle branch block and C) Hyperkalemia

Explanation: Right bundle branch block (RBBB) can cause a widened QRS complex, while hyperkalemia can also lead to widened QRS complexes. Atrial fibrillation typically presents with irregularly irregular heart rhythms, and first-degree heart block is characterized by a prolonged PR interval, not a widened QRS complex.

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