Can AVNRT be slow?
Slow/fast AVNRT was identified as having a long A-H interval (generally >200 ms) and site of earliest retrograde atrial activation located posterior to the tendon of Todaro, inferior to the level of the His bundle potential, indicating retrograde fast pathway conduction.
What is the slow pathway in AVNRT?
In the majority of cases of slow/fast AVNRT, which occurs in ≈90% of the patients, the anterograde slow pathway is formed by the rightward inferior extension of the atrioventricular node, which can be targeted for ablation with a low risk of atrioventricular block at the inferior triangle of Koch (between the tricuspid …
What would the ECG of someone with AVNRT look like?
Findings on ECG include the following: Narrow complex tachycardia. A P wave that occurs after the QRS complex (a short RP interval) Tachycardia that quickly terminates with AV blocking maneuvers (carotid massage or adenosine)
What does the slow pathway do?
Because the anatomic slow pathway is usually within the triangle of Koch, ablation in this region may eliminate an atrial tachycardia arising from the myocardium of the coronary sinus ostium.
When does AVNRT develop?
AVNRT is generally a narrow complex tachycardia with rates of 120 to 240 bpm. It generally presents in the first 2 decades of life but can occur at any age, and sometimes has a bimodal distribution with the incidence peaking in the late teens and again in the early thirties.
Where is the slow pathway ablation?
Sites of successful RF ablation of the slow pathway may be located anteriorly in the tricuspid annulus (cephalad to the coronary sinus os) or posteriorly (at, within, or caudal to the coronary sinus os).
What may cause AVNRT?
However, physiologically premature atrial contractions (PACs) and premature ventricular contractions (PVCs) precipitate AVNRT. Thus caffeine, tobacco products, alcohol, exercise, and/or emotional stress may increase the frequency of PACs and PVCs and therefore the frequency of AVNRT.
What is “fast-slow” AVNRT?
The atypical form of AVNRT, the so-called “fast-slow” form, is seen in approximately 5% of cases. The ECG in this type of AVNRT is markedly different. The reason is that in this form of AVNRT the conduction circuit proceeds down the fast pathway and back up the slow pathway figuratively leading to a long delay in ventriculo-atrial activation.
What is the difference between slow-fast and retrograde conduction in AVNRT?
In typical AVNRT the pathway with antegrade conduction is the slow pathway, whereas retrograde conduction is fast (hence called slow-fast AVNRT).
What should be the AH during tachycardia in slow AVNRT?
In slow/slow AVNRT, the AH during tachycardia should be >200 msec. 2 There are several articles that have been published on the differentiation of these subtypes utilizing various criteria; for the purpose of this article, we chose this simple method of measuring AH during tachycardia.
What are the conditions for AVNRT to occur?
A condition for AVNRT to occur is that 2 electric pathways occur in and around the AV node (a slow paced and a fast paced pathway). That gives way to the occurrence of re-entry. Two forms of AVNRT occur: typical and atypical AVNRT. Typical AVNRT (also described as common AVNRT or slow-fast AVNRT): The impulse travels over