Antiarrhythmic Drug Classes

Learning the Anti-Arrhythmic Agents just got a whole lot easier!
**MedImmersion to the rescue**
Listen guys, I really hope this video helps you in school. I definitely had fun making it! If you have questions, comments, or even criticisms...please, leave a comment. I love teaching and working with students, so your comments mean a lot to me!
Good Luck in school!
Hey KZbin, this is Dr. Joel.
In this video, I'm gonna be covering the antiarrhythmic agents.
I'm gonna start with a review of cardiac physiology, and then jump right into the agents themselves.
I'll cover the Class I, Class II, Class III, Class IV, Class V, and then just give you some departing thoughts and then I will finish off with a couple of knowledge challenge questions, just to see where you're at.
OK? Let's get started.
In order to do a really good review of the cardiac antiarrhythmic agents, it's first important important for me to cover a little bit of cardiac physiology, starting first with the cardiac action potential.
And that's because this action potential is a little bit different than the action potential that you're going to see in nerves.
Also, a solid understanding of this action potential will help you later understand why the drugs work the way they do.
So, this picture on the right represents a cardiac action potential.
And, one thing that you need to understand is that this action potential is going to be a little bit different depending on which part of the heart you're measuring.
However, the principles that I'm about to cover will apply to all of those tissues in the heart.
And, if you want to, you can click on this link, which will take you to a picture that I think does a really cool job about showing the differences in the cardiac action potential in the different sections of the heart and that also how all those electrical depolarizations add up to make the electrocardiogram wave form.
Anyway, on the X axis, we have time and on the Y axis, we have voltage.
In the polarized state, the heart rests at about negative 95 millivolts.
An action potential cycle takes about 200 milliseconds.
And that number changes depending on which part of the heart you're in or which tissue you're sampling.
So, on this graph, you can see that the heart starts at about negative 95 millivolts then it very quickly shoots up to about 20 or so, by this graph, pause at 20 millivolts.
It stays there for a bit, and then the cell starts to repolarize itself.
And that's the cycle.
I'm going to add a cell membrane at the top of this picture and I'm going to walk through the phases of the action potential one at a time and what I want you to do is, I want you to imagine that above this cell membrane is the extracellular space and below this membrane is the intracellular space.
OK, starting off with Phase 0, which is the depolarization phase.
This is caused by a opening of voltage-gated sodium channels.
And these are very fast, rapid-acting channels that allow a large amount of sodium to move very quickly.
Sodium is positively charged, so if positive things come into the cell, then the cell becomes more positive.
OK, does that make sense? Basically, that's why you see this huge skyrocketing here of the voltage from negative 95 to positive 20.
It's because those positive sodium ions are moving in very quickly.
Next is Phase 1, which is the initial repolarization phase, which is basically caused by the rapid inactivation of those sodium channels.
Almost as quickly as they open, they start to close again.
At the same time, voltage-gated potassium channels start to open allowing potassium to efflux or exit the cell.
Potassium is also positively charged.
So if you have positive things leaving the cell, then the cell becomes more negative, right? And that's why there's a little dip there in the voltage.
Next, with Phase 2, you get calcium channels and they begin to open.
Calcium, again, also positive.
Positive things coming into the cell would make the cell more positive.
But potassium is still moving out, so that would make the cell more negative, and hence you get this plateau phase.
It kind of balances out for a little bit.
It's not exactly flat, but it's close.
We still call it the plateau phase.
And, as you know, the calcium plays an effect on how the muscle cells contract.
So that's important as well for contraction.
Next is the rapid repolarization phase, which is Phase 3.
More of the voltage-gated slow potassium channels are opening and they allow more potassium to rush out and the calcium channels begin to close so the cell starts to move back down to a negative value, a strong negative value.
And you have to remember, the sodium-potassium ATPase pump is also chugging along this whole time.
It's still working, it's still pumping potassium in and sodium out, which is just another factor that is driving that cell back down to its polarized state.
Lastly is the fourth phase, which is the resting potential phase.

[@dge.]

This was by far the best video on Anti-arrhythmics i have seen... and I’ve seen A LOT. Thank you so much for imparting your knowledge with us, doctor. You have a very distinct and organized teaching style that allows your students to process the information as you go along the lesson. Not a lot of people could do this. I hope all of my med school professors were like you. Hoping to pass my exams! This video helped me regain my confidence in this topic (i was so close to giving up...) THANK YOU AGAIN! 💞

[@markulinos]

truly amazing..especially the part explaining refractory period and arrythmias! Pure gold! thank you so much!

[@jaquelinemanuel5716]

YOU ARE SOOO GREAT! I understand everything you have taught and explained on this video! More power! Thanks!

[@colleencampbell6718]

Thank you for doing this, medical students all around the world appreciate it. :)

[@JD-kv7tx]

It's been a while since you have done new content... glad to see your back... your doing great work and making a real difference... please keep it up!!

[@everlyneachieng5927]

Receive greetings from Kenya,I loooove it, you are amazing!! coupled with a captivating voice!!I have exams tomorrow on Anti-arrythmics and I am confident I will get everythingThank you so much!!!

[@shujayli1298]

this is one of the best module/teaching Ive watched thru my entire undergraduate and graduate years

[@kingsleyokoro9798]

Dude, your videos are a true life-saver! Got boards coming up and it makes this tough topic more manageable!

[@soso_blaze5521]

This is really my favorite channel... Thank you sir!!

[@user-nl6sz3ow5j]

Wow, Thank you for your endeavor!!! This is the best video I have ever watched!! Thank you so much !!

[@continentalg5]

Wonderful video with clear and concise explanations! Thanks so much for your time and effort!

[@javeriaamin2986]

Voice ❤ Way of expaling❤ Time saving Life saving Grade saving...keep it up..doing a great job

[@michellelee5120]

This is definitely the best anitarrhythmic drug lecture I've encountered. Thank you so much for making it and uploading it for everyone!

[@MedImmersion]

You're welcome Michelle!

[@jeromes5183]

Great video, Dr. Joel. Excellent narration, really kept me engaged. Screw my power points.

[@itsjustgettingeasier1843]

The best medical presentation and explanation i've ever seen! Thanks a lot. Keep going.

[@davidalexander6500]

Best explanations of cardiac action potential I’ve ever heard!

[@roozbehrzv]

Awesome. I have pharmacology exam on Saturday and your videos are keeping me up!! You know, studying all these lessons are sooooo hard: Basics of Pharmacology, ANS Drugs, Anti HTNs, Anti Anginas, Anti Arrhytmics, Diuretics, Anticoaggulants, AntiHistamins, Asthma Drugs, NSAIDs, Opioids

[@paramond6280]

I admire! THE BEST VIDEO ABOUT ANIARRYTHMIC DRUGS!

[@DermDrNik]

Your videos are phenomenal, thank you so much! I've learned a lot of pharmacology for the USMLE already just by watching these. If you're taking suggestions for topics, could you do an epilepsy one?

[@erikepskamp6410]

Great video, I will be sharing this in the Paramedic class I teach. Well delivered and explained. Thank you.

[@danhle5590]

this is so great!!! I'm reviewing for a pharmacology final and your videos are so helpful and clear! thank you

[@jeanahm5875]

You're a life saver! thank you so much. really helped me with preparing for my final exam tomorrow

[@nadeeyaaa]

amazing video..concise and comprehensive. I wish you all the best and please keep up the good work!

[@jamzki77]

ur voice is so soothing and relaxing! really easy to understand and great explanation! thanks!

[@jalitawickham4392]

Oh my. I must thank God for you. I totally understand arrhythmias and the drugs used for my upcoming test. I really appreciate it.

[@MedImmersion]

+Jalita wickham - I'm so glad I could help!

[@Pawsandclaws337]

You are best of the best! Cannot thank you enough!

[@trevspillman4]

I have my pharmacology test in paramedic school tomorrow and this video was awesome. Thank you so much for making it.

[@sam.kendrick]

Excellent video! You're a great teacher! Plus the links were very helpful.

[@sharelkaithathara2864]

best video on youtube for arrhythmia ...thank you

[@AhmedIbrahim-yf6ek]

amazing work, very well prepared

[@jackgreen7273]

GREAT SUPERB!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Great job dr. joel. you saved me a lot of time and left me with high understanding. The only thing is that you should have added a discussion on the Nodal action potential. Another thing is that there are some drugs that you dont want to use if the person has a heart failure due to the effects on lowering intracellular calcium. But the mnemonics and uses are great. thanks.

[@jingsuellis3595]

Super, super , Super!!!!!!!!!highly recommended!!!!!!!!!!!

[@praise139]

Thank you very much for this very well paced, knowledge rich and tip laden video. I'm studying for Pharma and this increased my knowledge base. Hope I can remember most of this in the exam.

[@lisa5483]

I wish I could like this video more than once! It's the best! Thank you so much!

[@SewueseAkuse]

LOVE this video! Really broke it down for me!

[@aggiekisakye674]

Thank you so so so much Doc. Thanks a lot! You guys are blessed 😍 I passed your test too!

[@EmiAbutineh]

Almost through my first year of medical school and I don't know how I've survived til now. You're videos are absolutely amazing, thank you so much! You make this material so much less daunting and help me understand both the pharmocology and the physiology it's targeting. #medimmersiontotherescue

[@MedImmersion]

+iman abutineh - Awww.. so nice. Thanks, I'm glad I could help. I felt the same way after first year.. you're gonna be a great doc!

[@robertgomez818]

Awesome Doctor please keep them coming 🙂

[@gervaisrocke715]

Really awesome video! Thanks a whole lot!

[@sunidhim.ghatikar3625]

If there was a team of saviours for med students, you'd be the leader, thanks!!!!!!!!!!!!

[@rahelkaaya5403]

this was amazing. keep 'em coming doc

[@MedImmersion]

+Rahel kaaya Absolutely!!

[@diafarrell2202]

This was great, concise and explanatory. Thanks a lot!!

[@sylviakazi5629]

Awesome Pawsome lecture!!

[@IntntnlProSatire]

Excellent, very clear yet concise, Thanks much!

[@karentrible268]

Excellent pace and explanations!

[@jeniferzabala7538]

Please, keep doing lectures, you have helped me a lot :)

[@yassinhelmy8375]

great video.. great teacher!

[@LeahhGB]

This was incredibly helpful. Thank you so much!!!

[@ilakianperunthagaimk8173]

Excellent video....

[@juliaharrigan8005]

the best video I have watched so far! you have to make more! :)

[@robertgomez818]

This definitely helped me with my PhD in cardiac electrophysiology TYSM

[@Bunny69Bee]

Excellent learning material

[@emekaezenwugo8359]

Many thanks! Keep up the good jaaaaab dude

[@michaelakamenska6819]

your videos are really very helpful as I better learn visually rather than by reading and imagining everything. I have a class test today and this is really awesome as last-minute revision. keep up the good work and add some more videos!!! Cheers!

[@MedImmersion]

Cheers

[@videosofmikey]

Your videos are saving my life haha, thank you med immersion!

[@fazeelathamid2961]

I have no words to say thank you.you are great

[@MultiGodgrace]

sir u explain so nicely and ur pnemonics are just fabulous sir. once again thank u very much.

[@sarojbk3122]

oh it is very useful lecture !I love it.Thank you very much

[@muneezajaved4588]

Sir you did a great job. Keep it up.

[@yapeihuang212]

I have a quiz of anti arrhythmic tomorrow, very helpful video~Thank you so much!

[@MedImmersion]

+黄雅佩 - You are welcome!! Good luck!!

[@inklisanpatel8847]

Great explanation sir...

[@lenahabdelgadir5194]

well done, super helpful

[@rickpaulsingh]

Thank you. Excellent video

[@faisalrehmat2092]

Fantastic job doctor ..keep it up .your video is really helpful and made my confusions clear..Thumbs up

[@hilarylewis8988]

a great lecture from a fantastic teacher. Thanks

[@shirinzannat3277]

Its really really awsome.final i can understand,many vdeos i found for easy.none was easy except u😍😇

[@singtrend]

Excellent short tutorial

[@raspberry9127]

pleaseeeee keep making videos because i really have problem understanding these topics from collage ..and thank you soooooo much

[@suzan9528]

Amazing job ....we need more of you videos plzzzz

[@taryke]

Great talk!

[@marinafoster4227]

Wow really great one Thank you!!

[@orpheecameron348]

excellent explanation. Thank you.

[@MaysYIsmail]

Great lecture! thank u!

[@malarvilimanikawasagam6000]

a great video almost covered everything. thank you

[@wenardrizabal9361]

Thank you for this review

[@DarrellRJr]

You are the GOAT doc

[@erindudemanperson]

I'm gonna watch this like 1,000 times. Great explanation!

[@MedImmersion]

+Steve Remington - Haha! Ok! Let me know if you have suggestions for improvements.

[@mosab0164]

thank you you are the best teacher ever this helped me so much

[@Bruno1743]

First, thank you for the great videos, they have been a lot of help. I wanted to ask how the ischemic tissue you were describing can only allow one-way propagation of the action potential? Thank you in advance!

[@leiunleng916]

it really helps a lot!! Thank you so much!! it's clear and better than my teachers :P

[@5holycows]

Very good video, thank you

[@alikhalid8846]

Little explanation of Class 1b Mechanism of action: Phase 0: block Na channels (little amount Na enter) Phase 1: initial repolarization Phase 2: plateau will be short than 200ms because in phase 0 (little amount Na entered) Phase 3: repolarization Phase 4: [(K out) (Ca and Na in) (-90mv)] then by other system called Na-K ATPase pump will return cell to normal [(K in) (Ca and Na out) (-90mv)]

[@staytuned3835]

very very good lecture. thank you so much. thanks alot

[@cygnelearning3605]

A happy medical student here. Thank you so much.

[@DrAssu]

thanx alot doctor u did such a great job in the explaining ,,it was really helpful ..god bless u plz keep it up

[@FlavioskaD]

thank you so much doctor! it helps me a lot!

[@nellyhoffman6194]

awesomeness !

[@junaidkhan1972]

Nice lecture ...thank you

[@adhithyannk9146]

Awesome.. thank you so much

[@fnyduru]

Thank You Soooo Much.. I enjoyed this lecture.

[@gangulan]

awsome video:)u rock!

[@katerinat4101]

Really helpful!

[@KJ-wq1wp]

Great video

[@cognitivenicnac]

you are great, thank you and God bless

[@darshanashah4475]

Amazing Thankyou tons you are saviour

[@natasharoychoudhury6891]

You are just phenomenal 😅

[@kaitlinjade2]

Thanks so much very helpful!

[@sruthigk9111]

Thank u sir for making this video. Its really helpfull for me .I need more classes for pharmacology. I hope u made more of this kind..

[@sil3ntmurder]

LOVED THIS. (from a singaporean med student)

[@deepsinmedicine]

i love your voice the videos are so helpful.