Atrioventricular Nodal Reentry

Aka: Atrioventricular Nodal Reentry, AVNRT, AV Nodal Reentrant Tachycardia

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II. Definitions

  1. Atrioventricular Nodal Reentry (AVNRT)
    1. Form of Paroxysmal Supraventricular Tachycardia (60% of cases) in which reentry occurs within the AV Node
    2. AV Node in AVNRT contains two pathways (one slow and one fast)

III. Pathophysiology

  1. Reentry Supraventricular Tachycardia in which the reentry occurs within the AV Node
  2. Circuit is composed of two pathways, one slow and one fast
  3. Reentry episode may be triggered by a Premature Atrial Contraction (PAC)

IV. Epidemiology

  1. Most common overall (60 to 66% of cases) type of Paroxysmal Supraventricular Tachycardia (PSVT)
  2. Most common in young adults, especially women
  3. Typically there is no underlying structural heart disease
  4. Increased onset with low Estrogen and high Progesterone states
    1. Luteal Phase of Menstrual Cycle (after Ovulation)
    2. Less common during pregnancy

V. Findings: General

  1. Heart Rate typically 160 to 190 (up to 260)
  2. P Waves are often hidden within the QRS (or appear immediately after the QRS)
    1. If P Waves are visible, they may appear as a S Wave in Lead II or Pseudo-R Wave in Lead V1
  3. Images
    1. cv_ekg_svt_avnrt.png

VI. Types: Typical (slow/fast) - 90% of AVNRT

  1. Course
    1. Starts with PAC passed down slow accesory path
    2. Signal travels retrograde up fast path
    3. Signal cycles back down slow accesory pathway
  2. EKG findings
    1. PR Interval > RP Interval
    2. Negative P Waves in III and avF

VII. Types: Atypical (fast/slow) - 10% of AVNRT

  1. Course: Reverse of typical pathway
  2. EKG findings
    1. PR Interval < RP Interval
    2. Pseudo-S Wave in leads I, II, aVF

VIII. Symptoms

  1. Regular, rapid, pounding Sensation in the neck (pathognomonic, LR+ 177)
  2. Provocative
    1. Standing up, after bending over
    2. May occur while lying supine in bed

IX. Signs

  1. Visible neck pulsations (LR+ 2.7)

X. Management

  1. Medical Management
    1. See Paroxysmal Supraventricular Tachycardia
    2. See Supraventricular Tachycardia
    3. Patients with Infrequent episodes with tolerable symptoms may wish to continue with only medical management
      1. Up to 50% of patients will ultimately become asymptomatic and cease to have recurrent PSVT
      2. Consider longterm suppressive therapy with Metoprolol or Diltiazem
  2. Catheter Ablation (Electrophysiology)
    1. First-Line Management for recurrent AVNRT

XI. References

  1. Colucci (2010) Am Fam Physician 82(8): 942-52 [PubMed]
  2. Delacretaz (2006) N Engl J Med 354(10): 1039-51 [PubMed]
  3. Helton (2015) Am Fam Physician 92(9): 793-800 [PubMed]
  4. Kumar (2006) Cardiol Clin 24(3): 427-37 [PubMed]
  5. Nasir (2023) Am Fam Physician 107(6): 631-41 [PubMed]

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