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pjrt

Permanent Junctional Reciprocating Tachycardia (PJRT)

Permanent Junctional Reciprocating Tachycardia (PJRT) is a rare form of incessant supraventricular tachycardia (SVT) caused by a slow-conducting, concealed accessory pathway, typically located in the posterior septum (near the coronary sinus).

PJRT is clinically important because it can produce persistent tachycardia, leading to tachycardia-induced cardiomyopathy, especially in children and young adults.

Primary Reference:

Mechanism

PJRT is a form of orthodromic AV reentrant tachycardia (AVRT) utilizing:

  • AV node → forward (antegrade) conduction
  • A slow, concealed accessory pathway → backward (retrograde) conduction

Because the accessory pathway conducts slowly, the tachycardia:

  • Is often incessant (ongoing for hours to days)
  • Has a long RP interval
  • Has P waves after the QRS, but earlier than in atrial tachycardia

The rhythm is typically 100–200 bpm, slower than typical AVRT.


ECG Characteristics of PJRT

Key features that distinguish PJRT from other SVTs:

  1. Long RP Tachycardia
    • RP interval > PR interval
    • RP is typically long because the retrograde conduction is slow
    • This is the defining ECG hallmark
  2. Inverted Retrograde P Waves
    • Seen after the QRS
    • Best visualized in inferior leads (II, III, aVF)
    • Polarity: Negative P waves inferiorly
  3. Narrow QRS Complex
    • Because conduction is via the normal His-Purkinje system
  4. Regular Rhythm
    • HR usually 110–200 bpm
    • Persistent or “permanent” in many patients
  5. Incessant Tachycardia
    • Often constant despite rest or sleep
    • May slow modestly but rarely terminates without intervention
    • Leads to tachycardia-induced cardiomyopathy
  6. Pseudo ST-Segment Depression
    • Retrograde P waves can deform the ST segment
    • May mimic ischemia

Differential Diagnosis: Long-RP Tachycardias

PJRT is part of the “long-RP tachycardia” family.

Condition Distinguishing Features
Atrial tachycardia (AT) P waves upright in inferior leads; warm-up/cool-down behavior
Atypical AVNRT Retrograde P waves near end of QRS; RP shorter than in PJRT
PJRT Inverted P waves, long RP, incessant rhythm, slower HR

PJRT is best identified by the combination of:

  • Inverted retrograde P waves
  • Long RP interval
  • Incessant pattern

PJRT vs Typical AVRT

Feature Typical AVRT (Orthodromic) PJRT
Heart Rate 180–250 bpm 100–200 bpm
RP interval Short Long
P wave Invisible or near QRS Visible, inverted in inferior leads
Accessory pathway Fast Slow, decremental
Pattern Paroxysmal Incessant
Cardiomyopathy risk Low High (chronic tachycardia)

Management Overview

Because PJRT is often incessant and causes LV dysfunction, early diagnosis is essential.

Acute Management

  • AV nodal blockers (adenosine, beta blockers, calcium channel blockers) may slow but often do not terminate the rhythm
  • Adenosine produces VA block but tachycardia usually resumes

Chronic Management

  • Beta blockers or calcium channel blockers
  • Amiodarone or flecainide for refractory cases
  • Monitoring for tachycardia-induced cardiomyopathy

Curative Therapy: Catheter Ablation

  • Slow-conducting accessory pathway is ablated
  • High cure rate (≈90%)
  • Dramatic improvement in LV function once arrhythmia eliminated

Sample ECG Images

PJRT Example – Long RP Tachycardia

Image to be added soon.

Typical features shown:

  • Long RP interval
  • Negative retrograde P waves in II, III, aVF
  • Narrow QRS
  • Regular rhythm

Atypical AVNRT (for comparison)

Image to be added soon.

Notice:

  • Retrograde P waves closer to QRS
  • RP interval shorter than PJRT

Key Takeaways

  • PJRT is a rare, incessant form of orthodromic AVRT using a slow accessory pathway.
  • Characterized by long RP interval, negative retrograde P waves in inferior leads, and regular narrow-complex tachycardia.
  • Often leads to tachycardia-induced cardiomyopathy if untreated.
  • Catheter ablation is highly effective and often curative.
  • Distinguish PJRT from atypical AVNRT and atrial tachycardia by RP interval, P-wave morphology, and incessant pattern.

pjrt.txt · Last modified: 2025/11/27 19:51 by dtong

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