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 KZread, 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.
Пікірлер: 179
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! 💞
truly amazing..especially the part explaining refractory period and arrythmias! Pure gold! thank you so much!
YOU ARE SOOO GREAT! I understand everything you have taught and explained on this video! More power! Thanks!
this is one of the best module/teaching Ive watched thru my entire undergraduate and graduate years
This is definitely the best anitarrhythmic drug lecture I've encountered. Thank you so much for making it and uploading it for everyone!
@MedImmersion
8 жыл бұрын
You're welcome Michelle!
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!!
Wonderful video with clear and concise explanations! Thanks so much for your time and effort!
Wow, Thank you for your endeavor!!! This is the best video I have ever watched!! Thank you so much !!
Dude, your videos are a true life-saver! Got boards coming up and it makes this tough topic more manageable!
This is really my favorite channel... Thank you sir!!
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!!!
The best medical presentation and explanation i've ever seen! Thanks a lot. Keep going.
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
8 жыл бұрын
+Jalita wickham - I'm so glad I could help!
Thank you for doing this, medical students all around the world appreciate it. :)
Great video, Dr. Joel. Excellent narration, really kept me engaged. Screw my power points.
Best explanations of cardiac action potential I’ve ever heard!
Voice ❤ Way of expaling❤ Time saving Life saving Grade saving...keep it up..doing a great job
Great video, I will be sharing this in the Paramedic class I teach. Well delivered and explained. Thank you.
You're a life saver! thank you so much. really helped me with preparing for my final exam tomorrow
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
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?
this is so great!!! I'm reviewing for a pharmacology final and your videos are so helpful and clear! thank you
ur voice is so soothing and relaxing! really easy to understand and great explanation! thanks!
I admire! THE BEST VIDEO ABOUT ANIARRYTHMIC DRUGS!
amazing video..concise and comprehensive. I wish you all the best and please keep up the good work!
I have my pharmacology test in paramedic school tomorrow and this video was awesome. Thank you so much for making it.
You are best of the best! Cannot thank you enough!
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.
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.
Excellent video! You're a great teacher! Plus the links were very helpful.
I wish I could like this video more than once! It's the best! Thank you so much!
This was great, concise and explanatory. Thanks a lot!!
LOVE this video! Really broke it down for me!
Thank you so so so much Doc. Thanks a lot! You guys are blessed 😍 I passed your test too!
best video on youtube for arrhythmia ...thank you
Excellent, very clear yet concise, Thanks much!
this was amazing. keep 'em coming doc
@MedImmersion
8 жыл бұрын
+Rahel kaaya Absolutely!!
This was incredibly helpful. Thank you so much!!!
amazing work, very well prepared
Excellent pace and explanations!
I have a quiz of anti arrhythmic tomorrow, very helpful video~Thank you so much!
@MedImmersion
8 жыл бұрын
+黄雅佩 - You are welcome!! Good luck!!
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
8 жыл бұрын
Cheers
Really awesome video! Thanks a whole lot!
oh it is very useful lecture !I love it.Thank you very much
Please, keep doing lectures, you have helped me a lot :)
I have no words to say thank you.you are great
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)]
Awesome Doctor please keep them coming 🙂
a great lecture from a fantastic teacher. Thanks
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
8 жыл бұрын
+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!
a great video almost covered everything. thank you
the best video I have watched so far! you have to make more! :)
Thank you for this review
Thank you. Excellent video
Excellent short tutorial
sir u explain so nicely and ur pnemonics are just fabulous sir. once again thank u very much.
pleaseeeee keep making videos because i really have problem understanding these topics from collage ..and thank you soooooo much
Amazing job ....we need more of you videos plzzzz
Excellent video....
excellent explanation. Thank you.
Super, super , Super!!!!!!!!!highly recommended!!!!!!!!!!!
Awesome Pawsome lecture!!
Excellent learning material
great video.. great teacher!
Many thanks! Keep up the good jaaaaab dude
Fantastic job doctor ..keep it up .your video is really helpful and made my confusions clear..Thumbs up
Great talk!
awesomeness !
This definitely helped me with my PhD in cardiac electrophysiology TYSM
I'm gonna watch this like 1,000 times. Great explanation!
@MedImmersion
7 жыл бұрын
+Steve Remington - Haha! Ok! Let me know if you have suggestions for improvements.
Sir you did a great job. Keep it up.
Great lecture! thank u!
you are great, thank you and God bless
Awesome.. thank you so much
thank you so much doctor! it helps me a lot!
well done, super helpful
Thank You Soooo Much.. I enjoyed this lecture.
Great explanation sir...
it really helps a lot!! Thank you so much!! it's clear and better than my teachers :P
thank you you are the best teacher ever this helped me so much
Wow really great one Thank you!!
very very good lecture. thank you so much. thanks alot
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!
Its really really awsome.final i can understand,many vdeos i found for easy.none was easy except u😍😇
Your videos are saving my life haha, thank you med immersion!
Great video thank you very much
thanx alot doctor u did such a great job in the explaining ,,it was really helpful ..god bless u plz keep it up
If there was a team of saviours for med students, you'd be the leader, thanks!!!!!!!!!!!!
A happy medical student here. Thank you so much.
Amazing Thankyou tons you are saviour
You are the GOAT doc
Thank you so much.☺️
Thanks so much very helpful!
Nice lecture ...thank you
Really helpful!
Thank you a million times
wow im impressed
Great video
You are just phenomenal 😅
may u get everything in ur life