Arrhythmias Flashcards
What is AVNRT?
-arrhythmias that represents 60% of arrhythmias presenting as SVT or PA and results from conduction through every entrance circuit comprising Fast and slow atrioventricular nodal pathways
Which pathway in AVNRT has the longer refractory period
Fast pathway
Which interval is prolonged in the beat that starts the reentry in ANRT?
PR interval
Notes on AVNRT:
- The reentrant circuit is located within the AV node
- in most cases, both the atria and the ventricles are stimulated by impulses exiting from the circuit during each lap
- neither the atria nor the ventricles are necessary for the maintenance of the reentrant circuit
- it is possible to have block in the his bundle, preventing the ventricles from being stimulated, without affecting the reentrant circuit
- it is possible to have retrograde block, preventing the atria from being stimulated but without affecting the arrhythmia
What is the typical heart rate during AVNRT?
150-250 bpm
What are symptoms associated with Avnrt?
Neck pounding, palpitations, lightheadedness, near syncope
Describe the location of the P-wave during AVNRT?
P-wave may be buried in the QRS complex or after the QRS complex, when will the P-wave is negative in the inferior leads and positive in lead V1, may manifest as small negative deflection in the inferior leads and small positive deflection in V1 (pseudo R prime pattern)
Characterize the onset and termination of episodes in AVNRT
Abrupt onset and termination
Is AVNRT more common in males or females?
Females
What is the typical age of onset of AVNRT?
After the age of 20 years
What methods can be used to terminate the AVNRT?
Blocking AV node conduction by changing autonomic tone or using pharmacologic agents
Which pathway should be ablated during AVNRT?
Slow pathway
Ablation of the fast pathway significantly increases the risk of complete heart block.
What anatomical site is typically used for ablation of the slow pathway?
Mid septal region between the contact AV node and the coronary sinus os to the posterior septal region around the os
Which symptom associated with AVNRT is typical for the clinical presentation for this arrhythmia but not in other SVTs?
Rapid regular pounding in the neck
What indicates a successful ablation for AVNRT?
- High-grade (2nd or 3rd°) heart block
- An increase in the refractories of the antegrade AV node
- Elimination or alteration in dual AV nodal physiology
Is the retrograde AV nodal conduction unchanged after slow pathway ablation?
Usually not
List complications of fast pathway ablation
-High-grade (second or 3rd°) heart block
Marked 1st° heart block
- Pseudopacemaker syndrome caused by prolonged AV conduction times resulting in atrial contraction during AV valve closure
- Persistence of atypical AV nodal reentry employing slow pathway as both the anterograde and retro grade limbs of the tachycardia
Describe the typical ECG presentation in AVNRT
Narrow, regular QRS complex tachycardia with no visible P-wave or P-wave located in the terminal portion of the QRS complex
List helpful ECG patterns to differentiate if a tachycardia is AVNRT
R prime pattern in lead V1
Pseudo-S waves in inferior leads
No discernible P-wave separate from the QRS complex
List three Diagnostic considerations for AVNRT in the EP lab
Typical AVNRT is rarely induced with ventricular pacing, this is the rule for atypical AVNRT
Administration of adenosine during the tachycardia helps differentiate and atrial tack from Etienne RT. If 80 block is produced while the atrial rhythm continues unchanged, this is highly suggestive of an atrial origin of the tachycardia.
Earliest activation at the low inter-atrial septum during tachycardia is consistent with AVNRT
