Heart Blocks (AV block) — NCLEX Cheat Sheet
Impaired AV conductionAlso known as: AV block · heart block · AV node block · bradycardia block
Use this quick-reference guide to spot, treat, and prevent Heart Blocks (AV block) on the NCLEX. Keep it handy during review and on exam day!
🩺📒 The 1-minute cheat sheet
📌 Types
- 1st: long PR, benign
- 2nd I (Wenckebach): PR lengthens
- 2nd II: dropped QRS, serious
- 3rd: complete, no P-QRS link
🩺 Signs
- Bradycardia, dizzy, syncope
- Fatigue, hypotension, ↓ CO
✅ Do
- Atropine for symptomatic brady
- Pacemaker for 2nd II / 3rd
- Transcutaneous pacing emergent
🚩 Report
- 3rd degree = emergency
📚 Heart Blocks (AV block) — full study notes
The cheat sheet above is your quick recall card. These notes go deeper — what it is, what to do first, what must be reported, and what to teach.
Key points
Understand these first- First-degree block shows a consistently prolonged PR interval greater than 0.20 seconds with every beat conducted.
- Second-degree Mobitz I (Wenckebach) shows a progressively lengthening PR interval until a QRS is dropped.
- Second-degree Mobitz II drops QRS complexes without PR lengthening and can progress to complete block.
- Third-degree (complete) block has atria and ventricles beating independently with no relationship between P waves and QRS.
- Higher-degree blocks cause bradycardia, decreased cardiac output, fatigue, dizziness, and syncope.
Nursing priorities
What to do, in order- Assess heart rate, blood pressure, level of consciousness, and signs of decreased perfusion.
- Place the patient on continuous cardiac monitoring and obtain a 12-lead ECG.
- For symptomatic bradycardia, administer atropine and prepare for transcutaneous pacing.
- Hold and report rate-slowing medications such as digoxin, beta-blockers, and calcium channel blockers as appropriate.
- Prepare the patient for temporary or permanent pacemaker insertion for high-degree blocks.
Red flags — report now
Escalate immediately- Third-degree block or symptomatic Mobitz II with hypotension or syncope is an emergency requiring immediate pacing.
- Sudden bradycardia with decreased level of consciousness, chest pain, or hypotension must be escalated now.
- Never delay transcutaneous pacing for a deteriorating, symptomatic high-degree block while waiting for medications to work.
Labs & values
Numbers to know- Digoxin level: therapeutic 0.5-2.0 ng/mL (toxicity can cause blocks)
- Potassium: 3.5-5.0 mEq/L (imbalance affects conduction)
- Troponin to assess for ischemic cause
Patient teaching
What patients must know- Report dizziness, fainting, extreme fatigue, or a very slow pulse to the provider.
- After pacemaker placement, avoid lifting the arm above the shoulder on the insertion side until cleared and avoid strong magnetic fields.
- Check the pulse daily and carry pacemaker identification at all times.
❓ Heart Blocks (AV block): NCLEX FAQs
What are the priority nursing interventions for Heart Blocks (AV block)?
Assess heart rate, blood pressure, level of consciousness, and signs of decreased perfusion. Place the patient on continuous cardiac monitoring and obtain a 12-lead ECG. For symptomatic bradycardia, administer atropine and prepare for transcutaneous pacing. Hold and report rate-slowing medications such as digoxin, beta-blockers, and calcium channel blockers as appropriate.
What are the warning signs of Heart Blocks (AV block) a nurse must report?
Third-degree block or symptomatic Mobitz II with hypotension or syncope is an emergency requiring immediate pacing. Sudden bradycardia with decreased level of consciousness, chest pain, or hypotension must be escalated now. Never delay transcutaneous pacing for a deteriorating, symptomatic high-degree block while waiting for medications to work.
What do I need to know about Heart Blocks (AV block) for the NCLEX?
First-degree block shows a consistently prolonged PR interval greater than 0.20 seconds with every beat conducted. Second-degree Mobitz I (Wenckebach) shows a progressively lengthening PR interval until a QRS is dropped. Second-degree Mobitz II drops QRS complexes without PR lengthening and can progress to complete block. Third-degree (complete) block has atria and ventricles beating independently with no relationship between P waves and QRS.
What patient teaching is important for Heart Blocks (AV block)?
Report dizziness, fainting, extreme fatigue, or a very slow pulse to the provider. After pacemaker placement, avoid lifting the arm above the shoulder on the insertion side until cleared and avoid strong magnetic fields. Check the pulse daily and carry pacemaker identification at all times.
Quick Tip
First-degree block shows a consistently prolonged PR interval greater than 0.20 seconds with every beat conducted.
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