Atrial Tachycardia

From Ask Dr Wiki

Jump to: navigation, search

Contents

Features

Atrial Tachycardia is a relatively common arrhythmia. It often occurs in paroxysms of abrupt onset and termination. The atrial rate averages 180-220 beats per minute and is usually quite regular. The ventricular response is usually 1:1. In cases due to Digoxin Toxicity the tachycardia usually has varying AV block.

Maneuvers to Diagnose Atrial Tachycardia

Supporting

  1. AV Response. During SVT pace at a Cycle Length 10 to 60 msec shorter than the tachycardia Cycle Length until 1:1 VA conduction
    1. If the tachycardia Terminates then Reinduce
    2. AV (AH) response. AVNRT or AVRT
    3. AAV (AAH) response. Atrial Tachycardia
  2. Development of AV Block during Tachycardia supports Atrial Tachycardia
  3. Atrial Activation Sequence that is not compatible with retrograde conduction through the AV junction or an accessory pathway.
  4. Failure to terminate or preexcite the atrium with a ventricular extrastimulus delivered when his bundle is refractory.
  5. Inability to have VA conduction during tachycardia

Against

  1. Tachycardia terminated with ventricular pacing or PVC without depolarization of the atrium.
  2. VA conduction interval changes with the development of BBB.
  3. Changes in the V-V precede changes in the A-A

Mapping Atrial Tachycardia

  • Entrainment mapping is used to identify sites within a macroreentry circuit but has also been shown to be useful in evaluating a focal tachycardia.
  • Atrial Overdrive Pacing consisting of eight paced beats at a cycle length 10-30 msec less than the tachycardia rate can be performed at the high and low right atrium, high septal location, and proximal and distal coronary sinus. The Post Pacing Interval - Tachycardia cycle length (PPI-TCL) in patients with AT was 11+/- 8 msec at the successful ablation site. At the site that the AT focus is localized the PPI-TCL approaches zero
  • The PPI-TCL can also be used to differentiate AT from sinus tachycardia since focal AT has a very short perifocal conduction and the sinus node has a long PPI-TCL (131 +/- 37 msec) due to time reuired to conduct through the perinodal tissue (sinoatrial conduction time).

Ablation of a Focal Atrial Tachcardia near the His

  • Need to go left sided to make sure that it is not a left sided tachycardia that uses Bachmann's bundle
  • Deliver single PACs and check p wave versus earliest local site to see if you are pre p wave. If you are you are at the early site and likely not left sided
  • Also must look at Non Coronary cusp with may look like the HIs is earlies. NCC Tachycardia may be sensitive to adenosine. A is usually bigger and at least equal in the non
  • Start ablating at low power 5 watts and increase slowly to 55 degrees with 4 mm. Keep ablating during slow junctional

References

  1. J Cardiovasc Electrophysiol, Vol. 18, pp. 1-6, January 2007
Retrieved from "http://askdrwiki.com/mediawiki/index.php?title=Atrial_Tachycardia"
Personal tools