Conduction properties of the inferior vena cava-tricuspid annular isthmus in patients with typical atrial flutter

J Cardiovasc Electrophysiol. 1997 Jul;8(7):727-37. doi: 10.1111/j.1540-8167.1997.tb00831.x.


Introduction: A functional region of slow conduction located in the inferior right atrium has been postulated to be critical to the induction and maintenance of typical human atrial flutter. We reexamined the potential role of functional conduction delay in the annular isthmus between the tricuspid valve and the inferior vena cava; it is within this region that such delays have been postulated to occur, and where interruption of conduction by radiofrequency energy application has been shown to eliminate typical flutter.

Methods and results: Thirty patients with type I atrial flutter (30 counterclockwise, 14 clockwise) were studied. Counterclockwise and clockwise isthmus activation times adjacent and parallel to the tricuspid valve were measured during three conditions: (1) atrial pacing in sinus rhythm, (2) atrial flutter, and (3) entrainment of atrial flutter. During pacing in sinus rhythm at progressively shorter cycle lengths, both counterclockwise and clockwise isthmus activation times remained unchanged; decremental conduction prior to flutter induction or loss of capture was not observed. Counterclockwise isthmus activation time did not significantly differ during flutter (68 +/- 23 msec), inferolateral tricuspid annulus pacing (71 +/- 23 msec), or entrainment of flutter (72 +/- 23 msec). Similarly, clockwise isthmus activation times did not significantly differ between flutter (65 +/- 22 msec), proximal coronary sinus pacing (73 +/- 21 msec), or entrainment of flutter (64 +/- 15 msec).

Conclusion: Decremental conduction is not characteristic of activation through the isthmus when activation is assessed parallel and adjacent to the tricuspid annulus. Functional slowing or conduction delay does not develop in this region during typical atrial flutter.

MeSH terms

  • Aged
  • Anti-Arrhythmia Agents / therapeutic use
  • Atrial Fibrillation
  • Atrial Flutter / complications
  • Atrial Flutter / drug therapy
  • Atrial Flutter / physiopathology*
  • Atrial Function, Right / drug effects
  • Atrial Function, Right / physiology
  • Cardiac Pacing, Artificial
  • Catheter Ablation
  • Electrocardiography
  • Female
  • Heart Conduction System / drug effects
  • Heart Conduction System / physiopathology*
  • Humans
  • Male
  • Middle Aged
  • Tachycardia, Ventricular / etiology
  • Tricuspid Valve / physiopathology*
  • Vena Cava, Inferior / physiopathology*


  • Anti-Arrhythmia Agents