Electrocardiogram (EKG/ECG) interpretation is a critical skill for nurses, and the NCLEX often includes questions on cardiac rhythms. Understanding the basics of EKGs will help you recognize life-threatening arrhythmias and respond appropriately.

This guide breaks down essential EKG concepts you need to know for the NCLEX, including rhythm identification, key waveforms, and clinical significance.

Understanding the Basics of an EKG

An EKG records the electrical activity of the heart and consists of three major components:

1. P wave – Represents atrial depolarization (contraction of the atria).
2. QRS complex – Represents ventricular depolarization (contraction of the ventricles).
3. T wave – Represents ventricular repolarization (relaxation of the ventricles).

Additional key components:

• PR interval – Measures the time from atrial depolarization to ventricular depolarization.
• ST segment – Indicates early ventricular repolarization.
• QT interval – Represents the total time for ventricular depolarization and repolarization.

Common EKG Rhythms on the NCLEX

1. Normal Sinus Rhythm (NSR)

• Regular rhythm, rate between 60-100 bpm.
• P waves present before every QRS complex.
• Indicates normal heart function.

2. Sinus Bradycardia

• Regular rhythm but slow heart rate (less than 60 bpm).
• Causes: Hypothermia, beta-blockers, increased vagal tone.
• Treatment: Atropine if symptomatic, consider a pacemaker if severe.

3. Sinus Tachycardia

• Regular rhythm but fast heart rate (greater than 100 bpm).
• Causes: Fever, dehydration, pain, stress.
• Treatment: Address underlying cause (fluids for dehydration, beta-blockers for symptomatic relief).

4. Atrial Fibrillation (A-Fib)

• Irregularly irregular rhythm with no distinct P waves.
• High risk of clot formation and stroke.
• Treatment: Anticoagulation (warfarin, DOACs), rate control (beta-blockers, calcium channel blockers).

5. Atrial Flutter

• “Sawtooth” P waves with a regular or irregular rhythm.
• Causes: Cardiomyopathy, ischemic heart disease.
• Treatment: Similar to A-Fib (rate control, anticoagulation, possible cardioversion).

6. Supraventricular Tachycardia (SVT)

• Rapid, regular heartbeat (150-250 bpm).
• Narrow QRS complexes, no visible P waves.
• Treatment: Vagal maneuvers (bearing down), adenosine, beta-blockers, cardioversion if unstable.

7. Ventricular Tachycardia (V-Tach)

• Wide QRS complexes, rate greater than 100 bpm.
• Life-threatening if sustained.
• Treatment: If stable, use antiarrhythmics (amiodarone, lidocaine). If unstable, immediate cardioversion or defibrillation.

8. Ventricular Fibrillation (V-Fib)

• Chaotic, irregular rhythm with no identifiable waves.
• Causes: Myocardial infarction, electrolyte imbalances.
• Treatment: Immediate defibrillation and CPR.

9. Asystole

• No electrical activity, flatline on EKG.
• Treatment: CPR and epinephrine (no defibrillation).

NCLEX Test-Taking Tips for EKG Questions

1. Memorize life-threatening rhythms – V-Tach, V-Fib, and asystole require immediate intervention.
2. Use the ABCs (Airway, Breathing, Circulation) – If the patient is unstable, interventions must prioritize oxygenation and perfusion.
3. Understand medication effects on the heart – Beta-blockers slow the heart rate, atropine increases it, and digoxin affects rhythm.
4. Know defibrillation vs. cardioversion – Defibrillation is for pulseless V-Tach and V-Fib, while synchronized cardioversion is for SVT and unstable A-Fib.
5. Identify key EKG patterns – Recognizing atrial vs. ventricular rhythms can help quickly eliminate wrong answer choices.

Mastering EKG interpretation is essential for passing the NCLEX and becoming a confident, competent nurse. Focus on high-yield rhythms, and practice applying interventions based on patient stability.