Mechanisms of cardiac arrhythmias | Tachyarrhythmias | Cardiovascular Pathophysiology |
Pathophysiology of cardiac arrhythmias
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Pathophysiology of cardiac Arrhhythmias:
The arrhythmias may be either bradyaarhythmias or tachyarrhythmias.
There are 3 basic mechanisms by which tachyarrhythmias may occur
1. Enhanced automaticity
2. Triggered automaticity
3. Reentry
1. Enhanced automaticity
This type of arrhythmias may poccur due to abnormality in the pacemaker cells.
Enhanced automaticity may occurif thereis increase in slope of the pacemaker potential or the Resting membrane potential becomes less negative. This may happen in case of excessive sympathetic stimulation and mild kyperkalemia
2. Triggered automaticity
This occurs in cells which are not having automaticity but automaticy is being triggered by someting. It involves due to generation of after-depolarization:
After depolarizations are of two types:
Early after depolarization which occurs during the repolarization phase of cardiac action potential. It occurs whenever action potential gets prolonged. QT interbal prolonation is a sign of prolonationof action potential duration and thus it may lead to early after depolarization and hence predisposes a person to arrhythmias.
Delayed after depolarization occur after the repolarization ends i.e in phase 4 of cardiac action potentia.
These after depolarization can lead to generation of impulse before the normal impulse reaches the contractile cells.
3. Reentry circuits:
Third mechanism for arrhythmias is reentry or movement of an impulse in a circus movement. If an impulse has 2 paths through which it can pass and these conducting paths differe electrically such that one is fast conducting path and th eother is slow conducting path, in that case of renetry of impulse may occur.
Reeentry may occur due to an anatomical defect (anatomical reenetry) or may be due to functional difference in the electrical propery of the cells (functional reentry).
Wolff-Parkinson syndrome is a type where arrhthmias occur due to anatomical reentry
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Пікірлер: 114
I have watched many lectures special about this topic almost 15 video but they couldn't make me understand. I am very pleased with ur lecture mam.all my doubts has been cleared .Thanks a lot from bottom of my heart.
@PhysiologyOpen
Жыл бұрын
Thank you so much. Somehow was not in very good mood today but your comment uplifted me. I am so glad
i have been looking everywhere for a proper explanation for the triggered activity.... nobody explained it like you did, thank you so much!!!
@PhysiologyOpen
3 жыл бұрын
Delighted ...physiology does make understanding pathophysiology conceptual
Ma'am please never stop making videos. We are eternally grateful to you 😭🙏
@PhysiologyOpen
Жыл бұрын
😊 hopefully I will not. Thank you 😊
Thank you mam it helps me to understand pharmacology
@PhysiologyOpen
3 жыл бұрын
Yup that was the aim...so glad
Thank you so much! Other videos seldom explain these small details so I couldn't understand it until I found you!
@PhysiologyOpen
3 жыл бұрын
Glad I could help!
Great video, thank you so much!!
@PhysiologyOpen
3 жыл бұрын
So glad it was helpful
Thank you so much - Finally understood the topic!
@PhysiologyOpen
3 жыл бұрын
😊
Thanks so much mam. God bless you for taking the effort to educate us. Huge respect for you
@PhysiologyOpen
3 жыл бұрын
Thankyou so much. It means a lot to me. I feel like my efforts are paying off. Thanks again
That is very helpful. Thank you🙏🏼
@PhysiologyOpen
3 жыл бұрын
Happy that the video helped 😊
Awesome explanation. Thank you
@PhysiologyOpen
3 жыл бұрын
It’s my pleasure 😇
Verry rare conceptual video Thank you 😊
@PhysiologyOpen
2 жыл бұрын
Thanks for the compliment
What a gretest effort
@PhysiologyOpen
3 жыл бұрын
Thankyou 😊
Just got all stuff in one show...I was so obsessed with books and others
@PhysiologyOpen
2 жыл бұрын
😊..Glad !
Thankyou so much ma'am , you explain everything so clearly🥺🙏
@PhysiologyOpen
Жыл бұрын
Thanks for liking
Wonderful 👏👏👏👏 You are solving medicine doubts so well
@PhysiologyOpen
Жыл бұрын
Integrated teaching
Thank you very much!
@PhysiologyOpen
2 жыл бұрын
My pleasure
Thank you sooo much Ma'am😊😊😊
@PhysiologyOpen
3 жыл бұрын
Most welcome 😊
Thanku so much ma'am 🙏🙏🙏
@PhysiologyOpen
3 жыл бұрын
Pleasure is all mine
Thank you!
@PhysiologyOpen
4 жыл бұрын
Welcome!
Very nicely explained Thank you maam
@PhysiologyOpen
Жыл бұрын
Glad you liked it
Excellent💯
@PhysiologyOpen
Жыл бұрын
Thank you!
So much love and respect from pakistaan
@PhysiologyOpen
3 жыл бұрын
❤️
Nice explanation
@PhysiologyOpen
2 жыл бұрын
Thanks 😊
Oh my gosh finally found it 🥹 Thanks madam ❤️
@PhysiologyOpen
Жыл бұрын
😊
U r awesome ma'am
@PhysiologyOpen
3 жыл бұрын
Thanks
Nobidy expaljned like this . Harrisson words explained clearly thankyou. If possibke regarding excitable gap thanyou
@PhysiologyOpen
3 жыл бұрын
Thanks and welcome
What are the causes of action potential elongation,,so EAD occurs,,plzz ans
A really good and conceptual video👍👍thank u ma'am Ma'am plss can you make video on nernst eq and it's application🙏🙏
@PhysiologyOpen
3 жыл бұрын
I am recently working on RMP and Nernst equation...will be released by next Sunday
@PhysiologyOpen
2 жыл бұрын
Was scrolling through some comments. Found this one where I hadn’t posted the link for rmp video...did you get it
@PhysiologyOpen
2 жыл бұрын
Rmp and Nernst equation: kzread.info/dash/bejne/d22XytignszdebA.html
Thank you soooooo much.😊😊😊......No teacher might not present arrthymias in this beautiful way.... One doubt out of context ma'am 😅.....How ischemia leads to calcium overload in the cardiac muscle cell
@PhysiologyOpen
5 ай бұрын
Because CaATPases doesn’t work well, also cell permeability increases
ma'am please explain chemical and neural regulation of respiration
@PhysiologyOpen
4 жыл бұрын
Yeah . Whole respiratory physiology is on the cards. Currently working on CNS
can this explain orthodromic, antidromic AVRT
@PhysiologyOpen
Жыл бұрын
Yeah they are form of reentry arrhythmias
Mam is it triggered automaticity or triggered activity??..braunwald says its triggered activity
@PhysiologyOpen
4 жыл бұрын
Both terms are used. I took from Harrison and Goodman Gilman. Triggered activity also very commonly used
Ma’am which book do u use / refer ?
@PhysiologyOpen
Жыл бұрын
Well i refer many to create a video - for this per se- guyton, ganong, goodman gilman, and harrison
Long live PHYSIOLOGY O
@PhysiologyOpen
2 жыл бұрын
😀thanks
At 5:58 you mention the channels will open as the membrane potential is above the threshold, but earlier you mentioned that calcium channels do not need voltage to open but time. Does this mean that calcium channels can open after a period of relaxation, but only if the membrane potential is above threshold?
@PhysiologyOpen
2 жыл бұрын
Channel closing occurs with time but opens due to voltage change
@avibose7930
2 жыл бұрын
@@PhysiologyOpen I understand now. Thank you. Good video. Digitalis toxicity would be good to mention. Re-entry a touch confusing.
@PhysiologyOpen
2 жыл бұрын
Ok. Thanks for the feedback
Mam delayed after depolarization can also be due to digoxin toxicity??, which decrease rmp and cell can autoexcite without any impulse.
@PhysiologyOpen
2 жыл бұрын
Yes
@faizankhan-jp2my
2 жыл бұрын
@@PhysiologyOpen thanku mam for explaining with crystal clear concepts and making physio + pharmacology very conceptual to understand😊😊
Mam, please upload a video on anterior and posterior wall myocardial infarction
@PhysiologyOpen
3 жыл бұрын
Please check my video on Current of Injury...in the end I have spoken about wall infarction...but you need to see the video for understanding the end part
@PhysiologyOpen
3 жыл бұрын
Hopefully you got the video
Hello ma'am you said the calcium channel unlike sodium channel open with time. If that so can you explain how or when or which potential sodium channel opens after the inactive state. Thank you.
@PhysiologyOpen
2 жыл бұрын
Calcium channels slow to open
@PhysiologyOpen
2 жыл бұрын
All sodium channels don’t open exactly at same potential. It’s a probability opening. So some convert from inactivated to closed state as well at less potential
How will hyperkalemia lead to decrease in RMP..Can you please explain..it will of great help!
@PhysiologyOpen
4 жыл бұрын
Put the values of potassium in the Nernst equation. You will notice that when extra cellular potassium increases, RMP becomes less negative...I.e depolarisation occurs...for underlying concepts will make a video
@akshatkhare8957
4 жыл бұрын
@@PhysiologyOpen Thanks a lot!!
@rishabhjoshi9136
3 жыл бұрын
@@PhysiologyOpen thank you mam
@rosy2493
3 жыл бұрын
Have u made video for this concept mam..?? What heading should I search mam..???
@PhysiologyOpen
3 жыл бұрын
Not yet...ok will release this video next week. Sorry for the delay
Madam sinus arrythmia is same ?
@PhysiologyOpen
6 ай бұрын
Physiological sinus arrhythmia is increase in heart rate with inspiration and decrease with expiration…pathological is different
Didn't understood re-entry
@PhysiologyOpen
2 жыл бұрын
Will try to do a detailed video on that
Mam, Arrhythmia due to reentry is too complicated can't understand properly
@PhysiologyOpen
9 ай бұрын
Need to make a separate one I think on reentry
@PhysiologyOpen
9 ай бұрын
Thanks for the feedback
@abhishek3375
9 ай бұрын
@@PhysiologyOpen yes mam
wrong concept between tachyarrythmia and tachycardia. when heart is more than 100, it is specifically tachycardia not tachyarrythmia. A-fib is a tachyarrythmia but is not tachycardia. A-fib become tachycardia when associated with pre excitation.
@PhysiologyOpen
Жыл бұрын
Thanks
Madam, RMP of cardiomyocytes is -90 mV. Threshold is how much ?
@PhysiologyOpen
4 жыл бұрын
Generally +15mv is the threshold. But we don’t draw in the action potential because it recieves the signal electrically from nearby cells (syncytium) and potential change is very fast, hence a straight line from RMP
@gyanpapisen7806
4 жыл бұрын
@@PhysiologyOpen I've understood it. +15 mV is the uppermost limit of Cardiac action potential or it's the threshold ? And one more doubt. Suppose action potential duration has got lengthened due to any reason. By now, L-type calcium channels have closed off. Now , due to reopening of the Calcium channels, won't a second pleatue appear as Calcium entry will nullity Potassium exit electrically? Why is the Calcium entry higher than potassium exit which results in an EAD unlike what happens in pleatue phase where both are equal in amplitude but opposite in polarity and hence the voltage inside the membrane doesn't change at all ? Kindly exolain, madam.
@gyanpapisen7806
4 жыл бұрын
@@PhysiologyOpen Kindly make a video on potassium channels and their types. I m still in an ocean of doubts regarding what inward rectifier, delayed rectifier potassium channels are. These appear like an enigma to me.
@PhysiologyOpen
4 жыл бұрын
Threshold..+15 mv from -90 so -75 is the threshold
@PhysiologyOpen
4 жыл бұрын
Oh sure...I would love to make a video on that...will make for sure
Oh my gosh finally found it 🥹 Thanks madam ❤️
@PhysiologyOpen
Жыл бұрын
😊
@PhysiologyOpen
Жыл бұрын
My pleasure