Cardiac Mechanics (preload, afterload, contractility, ejection fraction, and cardiac output)

Рет қаралды 54,412

3 жыл бұрын

A discussion of the factors that influence preload, afterload, and contractility; the calculation and methods to measure ejection fraction and cardiac output/index; and the Frank-Starling curve.
Contents:
@0:00 Introduction and Learning Objectives
@1:38 Preload
@5:38 Afterload
@10:09 Contractility
@11:39 Stroke volume, ejection fraction, cardiac output/index
@22:53 The Frank-Starling mechanism/curve
@27:18 Summary
#Cardiovascular #physiology #CV physiology

Пікірлер: 65

@OwenMcKinley 3 жыл бұрын

Hoping to see this series continued! These three video presentations that currently comprise it are phenomenal. Thanks so much 😊😊

@StrongMed 3 жыл бұрын

Thanks for the kind words! More videos in this series are definitely coming. I'm currently taking a break due to travel and a large non-medical DIY project (that will hopefully be featured on my other KZfaq channel once finished).

@OwenMcKinley 3 жыл бұрын

@@StrongMed Excellent! Best of luck with your project! I'm starting Perfusion school in a month and I've been reviewing cardiothoracic content on your channel. Top-level content, all around. Again, thank you 👍

@shiuantzer 3 жыл бұрын

So glad to have this online course during the pandemic in Taiwan…thank you!

@rodrigoferreiradarosa2977 3 жыл бұрын

Thank you, Dr. Strong! I’d love to watch the rest of the series and would be very interested in further in-depth lectures on this topic.

@DrAugrajUprety 3 жыл бұрын

it was splendid talk on the basics of physiology in cardiology!...thank you so much sir!

@ninae1853 3 жыл бұрын

Thank you Doctor Strong ❤️

@ahmedosman889 3 жыл бұрын

Thank you so much Dr. Eric for a wonderful video and Explanation.

@ridinrancher9443 Жыл бұрын

thanks for the video. I am considering getting my masters in Math with a biology track and cardiac mechanics is one class I may have to take. This helped shed some light on the subject.

@akashbaburaj2349 3 жыл бұрын

Thanks doc , ur every video is really good . The way you explain every topic with fine details shows ur commitment. hats off to u sir

@sunving 3 жыл бұрын

Thank you very much Doctor Strong. Very good lecture. I learn new thing from you. Probably need to re watch also. Your lecture is superb.

@tamannaislam2429 3 жыл бұрын

After watching your ECG videos directly liked the video without seeing it Thanks😊

@AtBackGarden Жыл бұрын

I just found this , and it's very helpful. Thank you very much.

@drshivsingh1394 3 жыл бұрын

Many thanks for these world class vedios Sir. Good bless you 🙏🙏

@abdulazizal-samawi8234 3 жыл бұрын

Thanks you Dr Symptomatology

@WaqarAhmed-ec5xp 3 жыл бұрын

u r really good teacher

@joetraveler5609 Жыл бұрын

Thank u Dr. Strong❤❤❤

@fjs1111 Жыл бұрын

Very good animation of the 3d method of disks, outstanding

@sunving 3 жыл бұрын

Thank you Doctor Strong. I just re watched and better understood. Your lecture is the best place . Oh may be if you have time , you could make another video regard to Covid , new vaccines , and the end game of Covid ect ….

@noorullahhamdard8145 2 ай бұрын

thank you Dear Mr Eric strong for the best prsentation as I ever watched in this field on youtube be successfull be strong

@nygeek6471 3 жыл бұрын

Thank you!

@adrianiordache4487 3 жыл бұрын

AWESOME!

@cornelbacauanu1544 3 жыл бұрын

Amazing clear explanation of difficult cardiac physiology and pathophysiology concepts, excellent correlation with clinically relevant parameters and their limitations. Thank you.

@dailydoseofmedicinee 3 жыл бұрын

👏👏

@MedSurvival 3 жыл бұрын

Thanks Dr. Strong. Helpful as always.

@yogeshlakshman8488 3 ай бұрын

Thank you for pointing out that preload and afterload doesn’t have universally same definition Because I have spent more time to understand this Now onwards my first go for cardiology for clinical practice will be Strong Medicine

@youssefrefaat1594 3 жыл бұрын

Sir, please continue similar videos on different systems. Thaaaaaaaaaanks!

@StrongMed 3 жыл бұрын

I hope to, but CV is going to keep me busy for a while!

@youssefrefaat1594 3 жыл бұрын

I am a med studnet and we really appreciate your efforts. I really like your videos and you made me fall in love with cardiology and internal medicine. I love how you explain things at great details, especially in the heart sounds series. You make us really understand things, rather than memorize. Any videos you make are definitly helpful, no matter what topic it is. Please keep it up. We appreciate your efforts. Thank you from Egypt!

@StrongMed 3 жыл бұрын

@@youssefrefaat1594 Thank you for the kind words!

@milkybeshir3115 3 жыл бұрын

@@StrongMed hi sir pls do video on leukaemia plsss???

@Thesharkmotivation 3 жыл бұрын

Please we need à video about long covid and treatment 🙏

@MBBSZaraHutKay 2 жыл бұрын

Thank You Sir .. waiting for next

@StrongMed 2 жыл бұрын

It's coming soon! Was working on it earlier today.

@MBBSZaraHutKay 2 жыл бұрын

@@StrongMed Thank You so much Sir from the depths of my heart... Love and Respect

@gregoryogunnowo9149 3 жыл бұрын

Master sword. Nice

@wolfpytlak2786 2 жыл бұрын

As a physiology TA I thank you for the Frank-starling and EF section, I knew hearth failure would "flatten" the graph, but i'd never put that much tought to how this was because due to changes on contractility, nevermind how afterload could manage to make the same changes, i'd never even heard someone say that preload and afterload status would change EF evaluation, this puts the whole HFpEF/HFrEF situation in a whole other light, makes me question a single EF measurment as an addecuate indicator of how should one treata patient. Do you have a recommended source to expand on this subject?

@StrongMed 2 жыл бұрын

The best resource for advanced physiology topics that I know of (particularly for cards & pulm) is the website, Deranged Physiology (derangedphysiology.com/main/home) run/written by Alex Yartsev, an Australian critical care doc. It's much better than any single physiology textbook I've found to date.

@user-wr9ks3tf4n 2 жыл бұрын

Hello doctor strong, may I ask a question? If the preload can also be defined by law of laplace, then I think the difference between preload and afterload is very confusing. If the venous return increased, not only the end-diastolic volume increase, but the systolic volume also increase ; moreover, if the systolic vascular resistance increase, then the transmural pressure during end-diastole will also increase, which will also lead to an increase of preload. I came across this question when studying arterial and venous vasodilator, which decrease systolic pressure and increase venous return respectively.

@lotfibouziane5227 3 жыл бұрын

Thank you dr Eric for your lectures. I would like to ask you why positive pressure ventilation decrease afterload ? I expected the opposite

@yousefmomani1619 2 жыл бұрын

kzfaq.info/get/bejne/ptKTpd14ubWmnas.html 03:23

@methodof3 Жыл бұрын

Cardiomyocytes have mechanosenstive ion channels that are permeable to caclium. These channels open as a function of cell cortex-membrane tension. This results in a flux of calcium from intracellular stores.

@PaulMcEvoyGuitars 3 жыл бұрын

Looking forward to watching this...I think you mean contractility (title)

@StrongMed 3 жыл бұрын

Yes, thank you! (Those are the silly errors that happen when I post videos at 4am!)

@tomterific390 2 жыл бұрын

It would seem, based on your list of factors influencing afterload, that increased preload is itself going to increase afterload, since chamber diameter would be increased, and thus increasing wall tension, right? Yet physiology texts I've seen state that the effects of afterload, (e.g. on the force-velocity relationship) can be offset by increasing EDV (i.e. preload). Can you please clarify?

@medicinalvl-up862 Жыл бұрын

Doctor a tension pneumothorax could another example for increased intrathoracic pressure?

@AumJi13 3 жыл бұрын

Yaaassss

@cutedogspuppies5711 2 жыл бұрын

Hello Dr. Strong. I am fascinated by u and ur great lectures. I have developed interest in internal medicine. Sir don't u think with advent of lots of superspecialities and again subspecialities within superspecialities the job of a internal medicine doctor has restrained to treatment only a few diseases ?

@StrongMed 2 жыл бұрын

Yes and no. A few years ago, I moved from a VA hospital (where everything non-surgical was admitted to medicine) to Stanford (where we have separate neurology, gen cardiology, heart failure, EP, oncology, hematology, hepatology, and pulm hypertension services). So on one hand, I see a more narrow range of primary problems, but those problems I do see can be far more complex than what I saw before. Your comment also seems very closely related to the video I posted this morning, in which I argued that the conventional organ system model that serves as the rough basis for the division of medicine into subspecialties is itself inherently flawed. There can be disease that might end up on a subspecialty service (e.g. cardiac amyloidosis, neurosarcoidosis, Wilson's disease presenting with hepatic failure, etc...) in which a complete understanding of the person's pathology can require someone whose perspective isn't biased by 3+ years of subspecialty training on just one organ. Are there days where I wish I saw more cardiology and maybe even completed a cards fellowship? Yeah, I have those days. But on the whole, I think I am more satisfied being better able to see the forest for the trees (no shade intended towards subspecialists).

@akshittuli1211 2 жыл бұрын

@@StrongMed I see what you did with the last phrase. Great play of words!

@ines4802 11 ай бұрын

I don't understand why in your explanation of afterload, wall tension and afterload are interchangeable. (when talking about the law of Laplace, "afterload is proportional to the LV pressure and the LV radius"). Thank you for the video

@medvid5271 2 жыл бұрын

Thanks you Dr.Strong! Currently, I have made some videos with Vietnamese subtitles from your videos. Could I do that with your permission? Thank you so much. Best regard.

@kodandaram5588 3 жыл бұрын

Need a ‘strong’ cardiac & vascular function curves video

@StrongMed 3 жыл бұрын

I know - don't worry, it's coming! (Unfortunately, I haven't yet had any bandwidth for making videos this summer)

@zeeshandesai8299 3 жыл бұрын

is this a part of another/new series?

@StrongMed 3 жыл бұрын

Yes! Cardiovascular physiology. Unfortunately, the videos take longer than my average to make, so I'll be releasing them interspersed with other topics or else my video frequency would drop significantly.

@srinivassri8521 3 жыл бұрын

Sir do u have chest x ray series notes?

@StrongMed 3 жыл бұрын

I'm sorry, I honestly don't. I made that series using a different workflow which doesn't allow the quick export of images in pdf format the way many of my other videos do.

@dr.derbyallen7063 3 жыл бұрын

Sir how to contact you to clarify my doubts ?

@StrongMed 3 жыл бұрын

If you have questions about the video content, you are welcome to post them here. However, I don't answer personal questions, and I am unable to provide specific individualized medical advice. (Not saying that's what you are asking about, but it is the most common reason viewers track me down off KZfaq, and unfortunately, I usually am unable to help them.)

@dr.derbyallen7063 3 жыл бұрын

@@StrongMed sir I have assigned myself as ur student, I don't need ur help for personal medical advice but for building my career. Please help .

@tasneemj7195 Жыл бұрын

Him: “if we cut the sphere in half we can see the interior cavity” Me: is that a MASTER SWORD???!!

@StrongMed Жыл бұрын

Yes. Yes it is. ;)

@poukpick465 3 жыл бұрын

Please give a subtitle

@StrongMed 3 жыл бұрын

Done (assuming you mean English subtitles). If you are asking for subtitles in a different language, unfortunately, I don't currently have the resources/support to provide that. (EDIT: I sincerely wish I could!)