Lecture Notes on Premature Junctional Contractions (PJCs)

Overview

• Presenter: Nurse Sarah
• Topic: Premature Junctional Contractions (PJCs), also known as Premature Junctional Complexes
• Definition: Early contractions originating from a focal point around the AV junction instead of the SA node, causing random early beats in the underlying rhythm.

Key Points

1. Characteristics of PJCs:

   • Nature: Premature, early contractions.
   • P-Wave Issues:
     • Can be concealed (hiding within the QRS complex)
     • Can occur before or after the QRS complex
     • If before, PR interval < 0.12 seconds
     • Inverted in leads aVF, II, and III if before or after the QRS.

2. Difference Between PJCs and Junctional Escape Beats:

   • PJCs: No pause before contraction.
   • Junctional Escape Beats: Pause occurs before the beat as AV junction takes over when the SA node fails.

Characteristics of PJCs

• Rhythm: Irregular due to random PJCs; underlying rhythm should be regular.
• Rates: Vary depending on the underlying rhythm.
• P-Waves:
  • Issues as mentioned before, but underlying P-waves should be normal.
• PR Interval:
  • Underlying rhythm: normal (0.12 to 0.20 seconds).
  • PJC: May not be assessable (if concealed) or < 0.12 seconds (if before QRS).
• QRS Complex:
  • Normal < 0.12 seconds, but occurs early with PJCs.
• QT Interval and T-Wave: Normal.

Example of a PJC

• Underlying rhythm: Normal sinus rhythm with premature junctional contractions.
• Example observation: Inverted P-wave close to QRS; PR interval < 0.12 seconds.

Causes of PJCs

• Increased Automaticity of AV Junction:
  • Commonly due to:
    • Digitalis toxicity
    • AV node injury (surgery, infection)
    • Congenital defects
    • Tobacco use
    • Electrolyte imbalances (potassium, calcium, magnesium)
    • Oxygen deprivation (e.g., myocardial infarction)
    • Hypoxia
    • Natural occurrence in some patients.

Treatment for PJCs

• Generally harmless if infrequent and asymptomatic.
• Concern: Frequent PJCs can decrease cardiac output and cause symptoms like chest pain, palpitations, and low blood pressure.
• Management:
  • Identify and treat the underlying cause (recall the pneumonic "Junction").
  • Educate patient on modifiable factors:
    • Smoking cessation
    • Limiting alcohol intake
    • Avoiding caffeine
    • Balancing electrolyte levels.
• Medication History:
  • Check for digoxin; notify healthcare provider if patient is taking digoxin.
  • Normal digoxin level: 0.5 to 2 ng/mL; levels above can indicate toxicity.
  • Antidote for digoxin toxicity: Digifab.

Conclusion

• Quiz: Available via the link in the description to test knowledge on the content discussed.