What is a his refractory PVC?
Figure 6: A His-refractory premature ventricular contraction (PVC) terminates the tachycardia without conducting to the atrium. The PVC blocks in the accessory pathway and this maneuver not only proves that the pathway is present but also is critical to tachycardia circuit.
How can you tell the difference between AVNRT and junctional tachycardia?
JT is an automatic focal tachycardia originating from the region of the compact AV node whereas AVNRT is a re-entrant circuit involving the slow pathway and fast pathway inputs to the AV node. Atrial extrastimuli can be used to distinguish the rhythms by exploiting this mechanistic difference.
How do you diagnose AVRT and AVNRT?
3. Slow-Slow AVNRT (Atypical AVNRT)
- Tachycardia with a P-wave seen in mid-diastole, effectively appearing “before” the QRS complex.
- May be misinterpreted as sinus tachycardia.
What is AVNRT?
Atrioventricular nodal reentry tachycardia (AVNRT) is the most common type of supraventricular tachycardia. People with AVNRT have episodes of an abnormally fast heartbeat (more than 100 beats per minute) that often start and end suddenly.
What is atypical AVNRT?
Atypical AVNRT was defined by delayed retrograde atrial activation with HA>70 ms. If the AH was <200 ms and the AH200 ms and AH>HA, the atypical form was considered slow-slow.
What causes 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.
Is AVNRT junctional tachycardia?
Introduction. Typical atrioventricular nodal re-entrant tachycardia (AVNRT) is the most common supraventricular tachycardia; however, junctional tachycardia (JT) is rare and occurs mostly in children or during infusion of isoproterenol.
What is AVNRT heart?
What is AVNRT tachycardia?
How is PHC used to differentiate AVRT and AVNRT?
PHC is a novel technique and an important addition to the armamentarium of maneuvers to differentiate AVRT and AVNRT. The electrophysiological differentiation of orthodromic atrioventricular reentry tachycardia (AVRT) from AV node reentry tachycardia (AVNRT) can be difficult.
When does atrioventricular nodal tachycardia ( AVNRT ) occur?
Atrioventricular nodal reentry tachycardia (AVNRT) Episodes often start and end suddenly, and occur because of a reentrant circuit — also called an accessory pathway — located in or near the AV node that causes the heart to beat prematurely. AVNRT tends to occur more often in young women, but it can affect both males and females of any age.
When to use AVRT to diagnose tachycardia?
If a late premature His complex (PHC; ≤20 ms ahead of the His) perturbs tachycardia, a diagnosis of AVRT is established because the late PHC cannot reach the AVNRT circuit due to the retrograde His bundle conduction time.
Why does a premature his complex ( PHC ) perturb AVRT?
We hypothesized that a premature His complex (PHC) will always perturb AVRT because the His bundle is obligatory to the circuit. Further, AVNRT could not be perturbed by a late PHC (≤20 ms ahead of the His) due to the retrograde His conduction time.