Junctional Rhythms

Premature Junctional Contraction (PJC)

  • PAC vs PJC:
    • PAC: Upright P wave.
    • PJC: Inverted P wave.
  • Sometimes, the inverted P wave is not visible and is hidden under the QRS complex.

Characteristics of PJC

  • Rate: Depends on underlying rhythm.
  • Rhythm: Irregular where the PJC occurs.
  • P waves:
    • Absent, inverted, or buried.
    • Retrograde (after QRS complex).
  • PR Interval: None or short.
  • QRS complex: Normal.
  • Example: Retrograde P wave after the QRS complex.
  • P waves can be hidden under the QRS complex.

Common Causes, Nursing Intervention, and Treatment

  • Treat the underlying cause.
  • Asymptomatic patients: No treatment needed (similar to PAC or PVC).
  • Frequent PJCs: Report to the doctor; treatment may be needed due to possible decreased cardiac output.

Junctional Rhythm

  • P wave changes:
    • Upper nodal area: Short PR interval.
    • Middle AV node: P wave may be absent.
    • Lower part: Retrograde P waves (after QRS complex).
  • P waves: Inverted before, immediately before, or immediately after the QRS complex, or hidden in the QRS complex.
  • Heart rate: 40 to 60 beats per minute.
  • PR interval: Short, less than 0.120.12 seconds.
  • P waves are hidden because the impulse release happens simultaneously with the QRS complex contraction.

AV Blocks and Junctional Rhythm

  • Differentiating can be confusing, but practice helps.
  • The electrical activity may not show the P wave clearly because the ventricular contraction occurs at the same time as atrial repolarization.
  • The rhythm is regular.
  • Originates from the AV node close to the ventricle.

Causes and Treatment

  • Causes: Acute MI, Digoxin toxicity, myocarditis infection.
  • Treatment: Treat the possible cause.
    • Heart rate 40-60 bpm.
    • Symptomatic patients: Atropine 11 mg every 3-5 minutes (max 33 mg).
    • If atropine is ineffective: Temporary pacemaker, possibly leading to a permanent pacemaker.
  • Polarization occurs at the same time as the QRS complex, so the P wave is not visible or it's after or before QRS complex.
  • Heart rate remains at 40-60 bpm.

Accelerated Junctional

  • Same characteristics as junctional rhythm, but heart rate is 61 to 100 bpm.
  • Inverted P waves.
  • If blood pressure is low and patient is symptomatic, administer dopamine instead of atropine.

Junctional Tachycardia

  • Same as above, but the heart rate is greater than 100 bpm.
  • P waves inverted before or after QRS complex, or hidden in QRS complex.
  • Paroxysmal junctional tachycardia: Occurs suddenly, then returns to previous rhythm.
  • Possible causes as before.
  • Vagal maneuvers if heart rate above 160 bpm
  • Cardiac ablation or Medications may be needed.

Junctional Bradycardia

  • Same characteristics, but heart rate is less than 40 bpm.
  • Inverted P waves before or after, or hidden in QRS complex.
  • Asymptomatic: No treatment.
  • Symptomatic: Administer atropine and use pacemaker.

Key Points on Junctional Rhythms

  • Inverted P waves immediately before or after the QRS complex.
  • If no inverted P waves are visible and the rhythm is regular, P waves are hidden in the QRS complex.
  • The AV node releases the impulse at the same time as the QRS complex, hiding the P wave.
  • Rhythm in junctional rhythms is regular.
  • PJCs do not occur every beat; they are premature contractions that occur sporadically.
  • Frequent PJCs can decrease cardiac output and lead to dangerous dysrhythmias.

Heart Rate Differences

  • Junctional rhythm: 40 to 60 bpm.
  • Accelerated junctional: 61 to 100 bpm.
  • Junctional tachycardia: Greater than 100 bpm.
  • Junctional bradycardia: Less than 40 bpm.

Steps to Identify Junctional Rhythms

  1. Check for inverted P waves.
  2. If P waves are inverted, it's likely junctional.
  3. Check the heart rate to determine if it's junctional rhythm, accelerated, or tachycardia.