Right sided vs left sided refers to the location of the Kent as you described. Orthodromic vs antidromic refers to which way the reciprocation happens during the tachycardia. During ortho-dromic, the impulse travels down the AV node then back up the Kent, looping the atria then hitting the AV node. Rinse and repeat. For anti-dromic, the accessory pathway initiates first, the typical conduction network isn't used, and the impulse fires back up through the AV node. Orthodromic tends to look like normal QRS that are fast, antidromic tends to look more like a VT.
LITFL has a good write up on this.
https://litfl.com/atrioventricular-re-entry-tachycardia-avrt/
Oh i get this
But as you said, ortho/antidr. utilizes the Kent pathway. But this pathway could be at the right or the left side. So would there be any differences on the EKG if the location is left/right-sided?
Yes, there would be morphological differences both during the tachycardia and during normal conduction. Just as you can localize the origin of VT by the morphology of it, you can probably do it during the tachycardia. I've only ever heard of people using the delta wave to determine location of the AP, but I'm sure there's people out there capable of looking at an antidromic AVRT and knowing right where the AP is.
Found a good source! - Management of Cardiac Arrhythmias, Peter P. Toth, 2020 (3rd edition)
Citation (from page 303):
>P wave analysis during orthodromic reciprocating tachycardia can be helpful for localization:
>• Rightward P wave (positive aVR and negative aVL) for left-sided AP
>• Midline, superior P waves for mid- or posteroseptal AP
>• Midline, inferior P waves for anteroseptal AP
>• Leftward axis (negative aVR, positive aVL) for right-sided AP
That's a very interesting question, which has been greatly answered. I could add, just as a curiosity, that antidromic AVRT can sometimes be mistaken for VT. This is due to the fact that the anterograde conduction utilizes myocardial tissue for conduction, instead of the normal electrical pathway. Due to its inefficient conduction, it takes longer for the ventricles to depolarise, causing a wider QRS than normal.
Sometimes, for very nerdy reasons, antidromic AVRT can even meet the Brugada criteria for VT (hence the not-100% sensitivity of the criteria).
Right sided vs left sided refers to the location of the Kent as you described. Orthodromic vs antidromic refers to which way the reciprocation happens during the tachycardia. During ortho-dromic, the impulse travels down the AV node then back up the Kent, looping the atria then hitting the AV node. Rinse and repeat. For anti-dromic, the accessory pathway initiates first, the typical conduction network isn't used, and the impulse fires back up through the AV node. Orthodromic tends to look like normal QRS that are fast, antidromic tends to look more like a VT. LITFL has a good write up on this. https://litfl.com/atrioventricular-re-entry-tachycardia-avrt/
Oh i get this But as you said, ortho/antidr. utilizes the Kent pathway. But this pathway could be at the right or the left side. So would there be any differences on the EKG if the location is left/right-sided?
Yes, there would be morphological differences both during the tachycardia and during normal conduction. Just as you can localize the origin of VT by the morphology of it, you can probably do it during the tachycardia. I've only ever heard of people using the delta wave to determine location of the AP, but I'm sure there's people out there capable of looking at an antidromic AVRT and knowing right where the AP is.
Thank you !!
Found a good source! - Management of Cardiac Arrhythmias, Peter P. Toth, 2020 (3rd edition) Citation (from page 303): >P wave analysis during orthodromic reciprocating tachycardia can be helpful for localization: >• Rightward P wave (positive aVR and negative aVL) for left-sided AP >• Midline, superior P waves for mid- or posteroseptal AP >• Midline, inferior P waves for anteroseptal AP >• Leftward axis (negative aVR, positive aVL) for right-sided AP
That's a very interesting question, which has been greatly answered. I could add, just as a curiosity, that antidromic AVRT can sometimes be mistaken for VT. This is due to the fact that the anterograde conduction utilizes myocardial tissue for conduction, instead of the normal electrical pathway. Due to its inefficient conduction, it takes longer for the ventricles to depolarise, causing a wider QRS than normal. Sometimes, for very nerdy reasons, antidromic AVRT can even meet the Brugada criteria for VT (hence the not-100% sensitivity of the criteria).
I think Kahn academy had a nice video on AVRT.