The Truth about Cardiac EKGs on the NCLEX

  • 13 June, 2022

If you experience a shiver down your spine when you hear the term "EKG", also known as an electrocardiogram, you are in good company. While EKGs can appear rather daunting at first sight, when broken down piece by piece, they slowly become less overwhelming and more enticing to dissect. Cardiac EKGs will most likely appear on your NCLEX, and it is in your best interest to be sure you know how to analyze different rhythms and be able to determine what intervention you as the nurse should proceed with. So, whether you feel overcome with fear every time you see an electrocardiogram strip or want a simple refresher, I have what you need! Let's look at some of the basics and discuss key factors to know for your upcoming boards.

The Truth about Cardiac EKGs on the NCLEX

1. First off, what is an EKG?

An EKG, or electrocardiogram, is really just a recording of the heart's functionality-it measures electrical signals, heart rate, and rhythm and can indicate if there are any probable concerns. While there are various reasons as to why someone may be referred for an EKG, today's focus will mainly be on how to accurately read one and decipher what your role is following its review.

2. How to read an EKG

There is an abundance of nitty-gritty details regarding how to analyze an EKG and what each minute detail indicates, but we will focus on some of the basics that will assist in answering questions that may appear on the NCLEX:

  1. Rate: In order to calculate the ventricular rate, you will count the number of R peaks on a six-second strip and multiply it by 10. To calculate the atrial rate, you will count the number of P waves and multiply that number by 10. If the rate falls within 60-100 beats, the rate is normal sinus rhythm. Following this, you will need to determine if the rate is regular, regularly irregular (inconsistent but follows a pattern), or irregularly irregular (no identifiable pattern).
  2. Rhythm: Analyze each of the PQRST complexes presented on a 6-second strip, including the distance between each one. Compare each complex to the next and check for the presence of each wave and whether they fall into a regular pattern. If they appear to be equal in distance, the rhythm is most likely normal; however, if there are odd spaces, the client may have an arrhythmia of some sort.
  3. P wave: This represents the contraction of the atria. Determine if there is a P wave present in each complex, and furthermore, assess to see if it falls within the normal 0.08-0.12 in duration. A normal P wave should not be taller than one large box in height. Irregularities or absence of the P wave can indicate disorders, such as atrial fibrillation.
  4. PR interval: Check to see if this interval falls within the correct range, .12-.20 seconds. Assess whether the EKG illustrates longer or shorter PR intervals.
  5. QRS complex: Assess the presence of these complexes and whether or not they fall between the normal range of about 1.5-3 of the small boxes on a strip. Are they too narrow? Too wide?
  6. T wave: This portion represents atrial relaxation. Are the T waves present? Are they peaked? Tall peaked waves can be an indication of an electrolyte imbalance, whereas inverted T waves may be a sign of ischemia.

As seen in the image below, it's important to note that each box on an EKG strip of paper is 0.04 seconds, and five of the small boxes is 0.20 seconds.

How to calculate EKG waves

Figure 1: How to calculate EKG waves 1

While most NCLEX questions will not directly ask you, "where is the P wave?", it is important to be able to recognize and determine what a normal complex looks like so that you can identify strips that are abnormal. More likely than not, the top two priorities on your boards are to identify a particular condition or to predict what intervention may be necessary after the review of an EKG strip.

EKG segments for normal sinus rhythm

Figure 2: EKG segments for normal sinus rhythm 2

Now that we have a basic understanding of what to look at when reading an EKG strip, we can take a deeper look into how to identify various conditions.

3. The different readings

  • Normal Sinus Rhythm

    Normal Sinus Rhythm EKG

    Figure 3: Normal Sinus Rhythm EKG

    • Rate is between 60-100 BPM
    • Regular rhythm
    • PQRST complex appears within normal range

  • Tachycardia
    Sinus Tachycardia EKG reading

    Figure 4: Sinus Tachycardia EKG reading 4

    • Atrial and ventricular rates both fall between 100-180 BPM
    • Regular rhythm
    • PQRST complexes present
    • Oftentimes this presents due to compensation for something occurring in the body (fever, caffeine, stress)

  • Bradycardia
    Sinus Bradycardia EKG

    Figure 5: Sinus Bradycardia EKG 5

    • Atrial and ventricular rates fall below 60 BPM
    • Regular rhythm
    • Normal PQRST complex ranges
    • Some individuals naturally have a lower heart rate; therefore, it is always important to assess whether or not the patient is symptomatic

  • Premature Ventricular Contractions (PVCs)

    Premature Ventricular Contractions EKG

    Figure 6: Premature Ventricular Contractions EKG 6

    • Early ventricular contractions-an extra beat that may cause the individual to experience a fluttering in their chest
    • The patient may or may not be symptomatic
    • Wide QRS complex
    • Can evolve into ventricular fibrillation

  • Ventricular Fibrillation

    Ventricular Fibrillation EKG

    Figure 7: Ventricular Fibrillation EKG 7

    • No identifiable P waves, QRS complexes, or T waves
    • Chaotic rhythm and rate
    • Most life-threatening abnormal rhythm and can be fatal if not resolved in a timely manner

  • Ventricular Tachycardia
    Ventricular Tachycardia EKG

    Figure 8: Ventricular Tachycardia EKG 8

    • Rapid heart rate above 100 BPM
    • Regular rhythm
    • Wide QRS complexes and P waves difficult to discern
    • Can lead to ventricular fibrillation and/or cardiac arrest

  • Atrial Fibrillation
    Atrial Fibrillation EKG

    Figure 9: Atrial Fibrillation EKG 9

    • Irregularly irregular rhythm pattern
    • Irregular ventricular rate ranging from 120-180 BPM
    • Atrial rate can vary from 300-700 BPM
    • No visible P waves

  • Atrial Flutter
    Atrial Flutter EKG

    Figure 10: Atrial Flutter EKG 10

    • Similar to atrial fibrillation but with a regular rhythm pattern
    • Regular, but fast rate
    • "Saw tooth" description

  • Asystole

    Cardiac Asystole EKG

    Figure 11: Cardiac Asystole EKG 11

    • No electrical or mechanical activity of the heart
    • Identified as "flatline"

  • AV Blocks
  1. First degree

    First Degree AV Block EKG

    Figure 12: First Degree AV Block EKG 12

    • Prolonged PR interval, greater than 0.2 seconds
    • Regular rhythm and rate
    • Patients are generally asymptomatic
  2. Second degree

    1. Type 1

      Second Degree AV Block

      Figure 13: Second Degree AV Block 13

      • Variable PR intervals
      • Irregular ventricular rhythm; regular atrial rhythm
      • Gradual prolongation of PR interval before a block occurs
      • PR intervals gradually become longer and longer and not every P wave will have a QRS complex that follows

    2. Type 2

      Second Degree AV Block EKG

      Figure 14: Second Degree AV Block EKG 14

      • PR intervals remain consistently distanced
      • Normal or bradycardic rate
      • Irregular ventricular rhythm; regular atrial rhythm
      • Skipped QRS complexes

  3. Third degree

    Third Degree AV Block EKG

    Figure15: Third Degree AV Block EKG 15

    • P waves and QRS complexes fire independently of one another (atria and ventricles working independently instead of together)
    • Regular rhythm
    • Typically bradycardic rate
    • Sometimes the P wave is hard to see and can become buried in the QRS complex
    • QRS complex may be more narrow
While it is essential to be able to recognize normal vs. abnormal readings, our job does not cease there. Once these have been spotted, it is our responsibility as nurses to be able to think ahead to what interventions may be required for the current scenario. Here are some potential interventions that may coincide with various abnormal EKG readings and conditions.

4. Interventions:

As with everything, the first action you will take, regardless of the cardiac rhythm, is to ASSESS the patient and determine what, if any, symptoms they are displaying.

  • Tachycardia: Pinpointing the root cause of the rapid heart rate will be the first action. Does the patient have a fever? Are they in pain? Are they feeling stressed? An increased heart rate may not be a sign of worry, as long as it is not sustained long term. First determine the cause and proceed accordingly from there. Beta-blockers, for example, may be required if the rapid rate is not a cause of something else.
  • Bradycardia:
    1. Determine any potential causes and assess whether or not the patient is symptomatic.
    2. Evaluate if a medication could be the cause and notify the PCP.
    3. If a patient is experiencing trouble breathing, administer oxygen per provider's orders.
    4. Atropine is a commonly prescribed medication for sinus bradycardia to increase heart rate in symptomatic individuals. Second line medications could include epinephrine or dopamine.
    5. If atropine is attempted and unsuccessful, a transcutaneous or permanent pacemaker may be ordered.
  • PVCs:
    1. Determine if the client is experiencing any symptoms, such as chest pain. Sometimes PVCs occur without any outward signs or symptoms. Treat the cause, if applicable. In rare cases, beta blockers may be necessary.
    2. If the patient is having difficulty breathing, it is best to notify the provider, provide the patient with ordered oxygen, and monitor oxygen saturation.
    3. Advocate to evaluate electrolyte levels as this can often be a cause of PVCs.
  • Ventricular tachycardia
    1. Decreasing the heart rate is the ultimate goal-administer prescribed antiarrhythmic medications, such as amiodarone.
    2. Be prepared to administer oxygen, whether the patient is stable or not.
    3. If unstable, the client may require cardioversion.
  • Ventricular fibrillation
    1. Given that the client lacks a pulse, CPR should be initiated immediately.
    2. Once a defibrillator is available, this should be utilized in conjunction with CPR.
    3. Oxygen will most likely be needed, as well as any prescribed antiarrhythmic medications such as epinephrine or amiodarone.
  • Atrial fibrillation
    1. While patients may not have any symptoms, if they are feeling lightheaded, oxygen may be prescribed.
    2. Since the rate and rhythm are both out of range, it is imperative to control these. Adenosine or digoxin could be prescribed for rate control while diltiazem and amiodarone can help to control the rhythm.
    3. Anticoagulants are often prescribed as well, given that the atria are not contracting to their full potential, putting patients at risk for emboli. Heparin or warfarin are often required.
    4. Cardioversion may be a helpful way to retrieve a normal rhythm, but this is not suggested for individuals who have dealt with atrial fibrillation long-term, as it could lead to a stroke.
    5. Atrial pacemaker can be another long-term option.
  • Atrial flutter
    1. Atrial flutter is not commonly life-threatening but can yield similar symptoms to atrial fibrillation if left untreated.
    2. Beta blockers, such as propranolol, or calcium channel blockers, such as verapamil, can be helpful in controlling the rate.
    3. Patients can also undergo cardioversion to alter the abnormal heart rhythm.
  • Asystole
    1. Perform CPR and utilize an AED immediately.
  • AV heart blocks
    1. First-degree AV heart block: There is usually no treatment required. The patient may need assistance with sifting through medications to be sure that none are worsening the condition. If the PR interval is extremely prolonged, a pacemaker could be necessary.
    2. Second degree (Type 1): Monitor and attempt to determine the underlying cause of the heart block. In more severe cases, when the patient has too slow of a heart rate, atropine may be required.
    3. Second degree (Type 2): Transcutaneous pacing will most likely be required along with the potential administration of dopamine if the patient is hypotensive.
    4. Complete heart block: Atropine is often prescribed to increase the heart rate, and transcutaneous pacing may be required for a symptomatic individual.

As nurses, we are often the first to view an EKG reading and can therefore save a life by knowing what could be a lethal read and being quick to respond appropriately. Even if you do not come across more than a handful of EKG-related questions on the NCLEX, this is still vital information for you to know as you initiate your career as a registered nurse.

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Silvestri, L.A. (2017). Saunders comprehensive review for the NCLEX-RN examination (7 edition.). St. Louis, Missouri: Elsevier.
2 Shutterstock, udaix, ID: 672180994
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About the Author: Kelsey Mangan

Kelsey Mangan is a registered nurse, who graduated from Linfield College in 2018 with a Bachelor of Science in Nursing and minor in education. She is a health and wellness advocate, writer, wife, and a new mama to baby Paisley. In her spare time, she enjoys working out, spending time with friends and family, finding binge-worthy shows on Netflix, and snuggling with her sweet daughter.

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