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Atrioventricular reentrant tachycardia (AVRT) & AV nodal reentrant tachycardia (AVNRT)

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Created by Bianca Yoo. Watch the next lesson: https://www.khanacademy.org/test-prep/nclex-rn/rn-cardiovascular-diseases/rn-dysrhythmia-and-tachycardia/v/ventricular-tachycardias?utm_source=YT&utm_medium=Desc&utm_campaign=Nclex-rn Missed the previous lesson? https://www.khanacademy.org/test-prep/nclex-rn/rn-cardiovascular-diseases/rn-dysrhythmia-and-tachycardia/v/multifocal-atrial-tachycardia?utm_source=YT&utm_medium=Desc&utm_campaign=Nclex-rn NCLEX-RN on Khan Academy: A collection of questions from content covered on the NCLEX-RN. These questions are available under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License (available at http://creativecommons.org/licenses/by-nc-sa/3.0/us/). About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content. For free. For everyone. Forever. #YouCanLearnAnything Subscribe to Khan Academy’s NCLEX-RN channel: https://www.youtube.com/channel/UCDx5cTeADCvKWgF9x_Qjz3g?sub_confirmation=1 Subscribe to Khan Academy: https://www.youtube.com/subscription_center?add_user=khanacademy
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Текстовые комментарии (76)
Tenzin Yangchen (26 дней назад)
Thank you
Mohammed Kabir (5 месяцев назад)
Amanda Trapp (5 месяцев назад)
This was so helpful, thank you so much!!
hati rose (7 месяцев назад)
beautiful! thanks
Irem Bozkurt (11 месяцев назад)
Not all heroes wear capes.
zuhair jumaah (1 год назад)
bad lecture
Med Life (1 год назад)
at 5:36 she said that the impulse can travel from the accessory node back to the AV node and cause a tachyarrythmia, my question is, since A/V node has a refractory period and can regulate the rate and rythm, why will the A/ V node cause tachyarrythmia, as in why will it let the impulse from accesory pathway through to begin with?
Punerdeep Sidhu (1 год назад)
This is the best video I could find on this difficult topic!
Ale Yup (1 год назад)
Very useful, thank you
Pallavi Sinha (1 год назад)
Really very well explained! Thankyou
DNC (1 год назад)
AMAZING video, Thank you very much!
Queen Mavichak (1 год назад)
Is it normal for nodes to have slow and fast pathways?! In the first example, how come the slow pathway doesn't go down the tract? Why is it halted when the fast pathway is going through refractory period?
Mark Younger (1 год назад)
Very good lecture. The only thing I would change is that the slow and fast pathways are not really "in" the AV node. The slow pathway is between the tricuspid annulus and the coronary sinus and the fast pathway is on the other side of the coronary sinus. Otherwise, excellent presentation.
Merna A (1 год назад)
more specifically it is in the triangle of coch...tendon todaro area. but YEAH!
Nebras Abu Abed (1 год назад)
wow !!!! now , I understand this concept much better !!!!! thank you !!!!!!!!!!!!
Daniel Navarro-Orozco (2 года назад)
Thank you, excellent video. My only comment is that the normal QRS width is .08-.12ms, this means that in order for it to be narrow complex the parameter should be <.08 not .12.
Lauren Southwick (2 года назад)
wow... leaving Thursday morning for mapping study plus or minus ablation with possible cryoballon... my hearts insane... I hope it works. thank you for this video!! would avrt or avnrt cause 17 pauses in 48 hours with the longest being 8.7 seconds?
keez ape (2 года назад)
why does the slow one even exist if the fast has a slow RP anyway... the slow is there for what ?
محمد حامد (8 месяцев назад)
This is abnormal .. it's not there in the normal hearts
Benjamin Goudeseune (1 год назад)
in a normal heart there's only one. Having two is a congenital heart defect.
Merna A (1 год назад)
fast pathway has a LONGER refractory period and the slow pathway is a SHORTER refractory period
eiskorn12345 (2 года назад)
Just a friendly note: you're sometimes really hard to understand for someone that English is a second language for - as you sometimes really speed up the words you say, especially in long, complex words, that might be clear to you, but are not clear to me. Thanks anyway!
Ikram Mohd Noor (2 года назад)
i'm crying, literally. got incoming internal medicine exam in 2 days, found this video, really give me a hope to pass the exam with flying colours. thank you very much, ma'am.
Irina Radoi (2 года назад)
Thank youuu <3
k.h (2 года назад)
8:14 so does that mean normally impulse conduction in avn down to bundle of h n so forth is done by fast pathway n not slow ? cuz u said slow comes down hits fast which is refractory n it goes refractory itself? plz any help
William Yates (2 года назад)
so good thank you from an intern!
Елена (2 года назад)
Wow I didn't know that the normal AV node has 2 pathways :-o none of my books mentions it :P thanks!
Patrick Morris (2 года назад)
The normal AV node has only one pathway, physiologically. The presence of two pathways is a congenital defekt.
akshay holla (2 года назад)
such an amazing way to explain svt
JesusBeloved18 (2 года назад)
This is amazing. Thank you so much!
graciously grace (3 года назад)
wow! you explained it amazingly well...thanks a lot!!
Mirza Omari (3 года назад)
Best video on the internet regarding this topic. Very few people can clearly and adequately explain it. Amazing job! Thank you!
Travisfromoregon (3 года назад)
Never realized how much the heart works like electronics.
Travisfromoregon (3 года назад)
Like nero fiber gel packs on star trek voyager? :)
derbigpr500 (3 года назад)
+Travisfromoregon The whole body works like an electronics device, a very advanced one. That's what humans are, biological machines. Imagine us designing robots, and then far, far, far into the future, when silicon and simple conductors aren't advanced enough, we'd have to start designing our robots out of biological tissue that is far more complex but still operates on similar basic principles.
Travisfromoregon (3 года назад)
Kinda slows it down, sounds like a resistor.
Travisfromoregon (3 года назад)
interesting, the refectory period is basically the same thing as a capacitor charging and discharging.
Merna A (1 год назад)
WOW now that you put it that way ...... that is so right
athena ky (3 года назад)
Ok if i pass my cardiology exams i will own it to you. really
athena ky (2 года назад)
+Andrei Plopeanu Girl don't loose your hope! Keep on trying. Cardiology is a pain in the ass. I was crying like a little baby the day before my exam. But I assed the exam :) Don't stop trying :) <3 I wish you luck :*
Andrei Plopeanu (2 года назад)
+athena ky Have mine next tuesday...this is the first video that makes things clear...started to loose my hope
Tzu Hsuan Cheng (3 года назад)
great video!
Doc (3 года назад)
Are the P waves absent in both AVRT and AVNRT? Please explain the mechanism for why the P waves are absent in either.
Елена (2 года назад)
+athena ky λοιπόν απ το όνομα υποθέτω εισαι Ελληνίδα και απ τις απαντήσεις σου καταλαβαινω οτι εισαι σε μεγαλύτερος έτος απο μενα, οποτε θελω να σε ρωτήσω κατι :P απ τη στιγμη που το re-entry mechanism γινεται ξανα και ξανα στο AVNRT, τοτε τι γινεται με τα νέα impulses που φτάνουν στο AV node απο το SA node ενώ ταυτόχρονα γινεται το re-entry? με συγχωρείς που τα μισά στα γράφω στα αγγλικά, αλλά σπουδάζω στα αγγλικά ιατρική και κάποιους όρους δεν τους ξερω στα ελληνικά 🙈
six1996 (3 года назад)
+Doc there is still a p waves, but they are being hidden by the overwhelming impulse in SVT
athena ky (3 года назад)
Sorry for my english... I will try to explain it... P waves represent the stimulation of atrium.. Sometimes electric signals from the reentry mechanism will travel towards to the atrium and towards to the ventricles... If this signal stimulate the atriums there will be a p signal which is going to be (-) in the II and (+) avR which means the atriums werent stimulate from sinus
Alirra Terrens (3 года назад)
this made it so clear. THANK YOU
Chase Dear (3 года назад)
Just had my 2nd ablation, 3 days ago, for WPW. 10 years between procedures. Thought we had it beat (no pun intended). Hoping this one is a permanent fix!
Imogen McIntyre (2 года назад)
+Chase Dear  Hi I am thirteen, and last year in November l had my first keyhole ablation, I haven't had any episodes so far and I used to have strange episodes, at least, every two months I was wondering how long it took for your symptoms to come back, in case mine do, because I really don't want to take the meds for it, and I do not want to do nothing as they said as one of the options for me. So I took the option for the surgery because I didn't want it to define me for the rest of my life. You know how people are... "Oh, you came first place in that race, But don't you have that thing wrong with your heart? You didn't feel faint as you crossed the finish line?" I'm sure you know what I mean by those dumb people who assume everything... But yeah my surgeon said after a year they could take out my implant that tracks my heart (reveal device). So I was wondering if it took over a year or under to come back in case mine does (fingers crossed it doesn't) :) .
Matt Chan (3 года назад)
+Chase Dear All the best mate! Hopefully have it covered now!
Kallmann Choong (3 года назад)
3rd question, since the reentry phenomenon is going to revolve around the AV node and the accessory pathway in a vicious cycle manner, there will be new electrical signals coming from above (SA node/atrial pacemaker cells) too right? wouldn't that cancel off the reentry mechanism and lead to a normal anterograde conduction again, if that's the case, how can it still be said "the reentry circuit phenomenon takes place over and over and over again".. because it doesnt..??
Mhd Awada (3 года назад)
The normal sinus rythm (SA node signal) will be blocked due to the refractory period of the reentrant circuit. And you are correct, the sinus rythm might stop the AVRT if timed precisely.
Kallmann Choong (3 года назад)
Question: 1.) In AVRT (WPW syndrome), since electrical signals are going to inevitably travel through both the AV node and the accessory pathway, does that mean the person will have a relatively higher resting heart rate even without a premature impulse? (owing to the lack of mechanism that slows down the signals in the accessory pathway) 2.) In 5:12 you mentioned that IF there was a premature beat, it would eventually form a reentry circuit by the signal that undergoes the AV node back up to the accessory tract at the time its refractory period is over , so my question is what if there was a premature beat that travels to the accessory pathway that wasn't in refractory period in the first place? Now does it differ from normal condition without a premature beat? and what determines the refractory period of this accessory pathway? +khanacademymedicine  or Anyone kind enough to enlighten me please? Thanks alot in advance!
Mhd Awada (3 года назад)
1. The resting heart rate without a premature beat depends on the SinoAtrial node rate. 2. The premature beat will travel to the ventricle and it will beat prematurely, thus the delta wave appears.
Doda Doda (3 года назад)
u r brilliant
Peter Fuchs (3 года назад)
James Perry (3 года назад)
Thank You so much for the thorough explanation.  I was diagnosed in 1998 with AV Nodal Reentry Tachy, had an ablation shortly thereafter to treat the condition.  However, after the procedure my doc informed me that the affected area was too close to the a/v node, and he was not able to completely get all of it.  So fast forward to today, I average 4 to 6 skipped beats per minute, with the occasional runs of tachy occurring.  I am back on the heart meds, taking Metoprolol extended release 100mg 1x per day.  I just somehow feel like this will be the bugger that gets me in the end.  At least I now know what is happening inside my chest,  Thank You :) 
Jasleen Jaura (3 года назад)
w8t2009 (3 года назад)
If you have AVNRT dont make ablation for it, doctors will tell u its a EASY fix, no complacations bla bla bla. What they dont tell you is that ablation creates a scar, the SCAR it selfs creates abnormal signals making you have PVC.  And you DONT want pvc, it the absolutely the worst thing u can have, u cant sleep, u cant eat, u cant enjoy anything because of them. If u go back to the doctor the will laugh and say " everybody has them" " in normal heart pvcs is not a issue" The doctors really dont know what a PVC are, they never experienced it, if they did they would never say something like that. I rahter have my AVNRT back with another pathway, so i have 3 path ways in my AV node rahter than these PVCS
Neeraj Narang (3 года назад)
+Lisa Nicholson . hi i m neeraj. anesthesiologist. indian. in one of my or, i heard that one of the nurse had cof palpitation. so i told her to get an ecg. then we found out that she had wpw , showing short pr interval and delta waves. she was then reffered to a cath lab and then radiofrequency ablation of abberant conduction pathway was done . after the procedure she was ok.
Lisa Nicholson (3 года назад)
I'm a med student and I wasn't aware of the issue with PVCs; I'll try to make sure I inform my future patients of the risk/ benefit, and take people more seriously when they complain of PVCs. We're taught in school exactly what your other docs said; that they're just no big deal. I'm sorry you're going through this. 
lindokuhle methula (3 года назад)
you are awesome! :)
Ana Palmeiro (4 года назад)
Thank you!
Lorraine Gary (4 года назад)
The video says that a supraventricular tachycardia involves a narrow QRS <~ 0.12sec.  In other readings, I find that normal QRS is < 0.12 seconds.  What distinguishes the two?  Is it, primarily, the heart beat?
Hamizah Mohd Razib (3 года назад)
+Lorraine Gary what i was being taught, essentially narrow QRS means that the problem doesnt lies on the ventricular muscles. To make it simple, broad QRS should make you think of either bundle branch block or ectopic(s) that originates from the ventricle if that makes sense?
Seda Kahraman (4 года назад)
Normal QRS time is two or two and half small square.But AVRT QRS time shorter than normal QRS.Because there is a extra signal in AVRT and QRS and refractory period become smaller
Abraham Rizkalla (4 года назад)
Great video! Can you tell us what software you've used to create this video?
Vlad Bucica (4 года назад)
But does the reentrant circuit send signals upward to the atria ?
David Ng (4 года назад)
yes it does. you may find inverted P waves after the R waves in the QRS complexes of AVNRTs (the R comes down and goes just below the baseline like a little hook, before returning to the baseline). This represents the retrograde depolarisation of the atrium from the AV node. 
Vitamin.A.B.E (4 года назад)
OMGGGG ladyyy your breathing is killing meeeeeeeeeeeeeeeeee
Hung Nguyen (3 года назад)
Latoya Williams (4 года назад)
What is the difference between Sinus Tachycardia vs SVT? The absence of the Pwave or the combining of the P wave with the T wave??
Nikolas Stanley (3 года назад)
+Mhd Awada Yes but in an emergency medicine setting paroxysmal SVT generally refers to AVNRT or AVRT (though an EP study is required to confirm). 
Mhd Awada (3 года назад)
Sinus tachycardia is one type of the SVTs. So SVT is a category and not a certain arrhythmia
Nikolas Stanley (4 года назад)
Sinus-Tach is benign in a structurally healthy heart, but may be very uncomfortable, and anxiety inducing requiring treatment with anti-arrhythmatics. 
Nikolas Stanley (4 года назад)
Neither. Though P-waves are absent in most all SVT's, Sinus-Tach presents as a perfectly normal sinus rhythm, simply with an elevated heart-rate over 100 BPM.

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