Long QT Syndrome and Torsades de Pointes, Animation
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- čas přidán 4. 07. 2024
- (USMLE topics, cardiology) Long QT syndrome: causes, pathophysiology, how LQTS causes TdP, diagnosis and treatment.
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Long QT syndrome, LQTS, is a condition that affects the heart’s electrical activities. LQTS is largely a genetic disorder: children inherit mutations from their parents that either cause the disease since birth, or make them more susceptible to develop it later in life when triggered by certain medications or metabolic imbalances.
LQTS itself is not the problem, many people with the syndrome don't have any symptoms and may not even be aware of it. However, it predisposes the patient to a life-threatening type of abnormal heart rhythm, known as torsades de pointes, which may lead to fainting, seizures, or sudden cardiac arrest. This complication is usually triggered when heart rate accelerates by adrenergic stimulation, such as during exercise, stress or strong emotions. LQTS can cause sudden death in seemingly healthy young people.
On an electrocardiogram that records electrical activities of the heart, P wave represents atrial depolarization, QRS complex is produced by ventricular depolarization, and T wave corresponds to ventricular repolarization. The QT interval, measured from the start of Q wave to the end of T wave, reflects the time taken for ventricular depolarization and repolarization, which is basically the duration of action potentials in the cells of the ventricles.
An action potential is essentially a brief reversal of electric polarity of the cell membrane. It is made possible by the flow of ions in and out of the cell, through specific ion channels. Basically, the depolarizing phase is caused by sodium influx; early re-polarization is due to initial outflow of potassium; plateau phase occurs when potassium efflux is balanced by calcium influx, and repolarization is when potassium efflux dominates calcium influx. The duration of repolarization is determined by the balance of current flow through these ion channels.
The rate of repolarization is slightly different for the 3 layers of the heart wall: the epicardium, mid-myocardium or M-cells, and endocardium. Because M-cells have less potassium channels and more sodium channels, they repolarize more slowly. On an ECG, the peak of T wave reflects repolarization of epicardial cells, while the end of T wave corresponds with repolarization of M-cells.
Long QT syndrome is due to prolongation of underlying action potential durations, and is most commonly caused by mutations in various ion channels that affect the balance of ion flow. Specifically, a reduced outward current caused by loss of function of potassium channels, or an increased inward current caused by gain of function of sodium or calcium channels, would increase the duration of repolarization. If inward currents exceed outward currents during the plateau phase, early after-de-polarizations and consequently extra heartbeats can be triggered. Mutations in ion channels also disproportionately lengthen action potentials in M-cells, increasing the difference in refractoriness of the different layers. This can cause electrical impulses to travel around in loops, known as re-entrant pathways, producing the characteristic wave pattern of torsades de pointes.
For diagnosis, patient’s QT interval is measured. But because QT interval varies with heart rate, a corrected QT interval, QTc, is calculated after measurement. Diagnosis, however, cannot rely on QTc values alone. Asymptomatic patients can have longer than normal QTc and develop no arrhythmias, while patients with established long QT syndrome may have normal QT intervals at rest. Diagnosis must therefore also include genetic testing, personal history of fainting, and family history of sudden death.
Treatment aims to prevent a long QT heart from developing dangerous arrhythmias. Most patients are treated with beta-blockers. Medications that shorten QT interval may also be prescribed. On the other hand, medications that prolong QT interval or precipitate development of torsades de pointes must be avoided. Patients are also advised to seek immediate treatments for conditions that may result in low potassium in the blood.
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This is seriously the best video i've watch so far for torsades de pointes! thank you!
Really excellent. This video cleared up SO MANY THINGS for me. Amazing work.
I am in awe of how good this video is. Truly, job well done!
Very detailed, clear and direct explanation! Thank you so much
Amazing video! You are very specific with your explanations and visual demonstrations of torsade de pointes! Thank you very much
Man, that was great! Thank you!
All of your videos are awesome.... So glad I found your channel
U expalined it very well.... This is the explanation i was searching for.... Thanks a lot
This video is perfect. Thank you.
Would love a video on early repolarization syndrome! You explain things very well!
That was fantastic, much thanks!
Your content is so touching
This was extremely helpful. Thank you very much:)
Truly crystal clear! Thank you
Glad it was helpful!
Very informative and well explained.. thank u for providing this...
Greatest ECG explaination ever
so touching for an excellent video
Amazing , very detailed explanation👍👍
What an incredible video ! Thank you so much for your comprehensive, thorough, and clearly spoken information you have shared ! Please continue to make more Life saving videos on health like this one ! Thank you and God bless you ! ❤🙏🍎👍🌹
Will do. Thanks
GREAT, thanks! especially interesting that appointment about the different refractory period among the different myocardium layers
Very well presented!!
Thanks lady , stay blessed.
Thank you! You too!
very concise. thank you
That was a clear explantion of LQTS!!!tnx
Wonderful video. So well explained and all possible and important information in a 5 min video. Amazing. 👍
Thank u very much! Very good Video!
this is a brilliant effort...v fundamental knowledge in such a concise and relevant manner.I would love to know if the publishers lets me know which books are they studying for medicine.
In future I will always prefer ALILA Medical Medical to others and I hope that I find this splendid approach to topics.
Kamal
It's concise and helpful
Thank you ❤️
Thank you, Helpful
THANKYOU SO MUCH🫡🫡🫡🫡
Extremely helpful, amazing explanation Power, beautiful animation, fallen in love 💕🌹👍👍👍👍👍👍👍👍
nice lecture very helpful
Easy explanation thnk u
excellent video
Much Thanks 💘
Just Amazing 👏
Thanks
Beautiful.
Clear Attractive Explanation ... thank you so much for this creative effort 👍👍👍
My golly its absolutely very good.
There is no more reason why medical students in this age/generations can't grasp and failed on this topic compare on my generation 2 and half years ago.
During my time, I just keep on imagining what Harisson has been saying which to this day is still confusing until "NOW".
Thanks.
Correction.
....its 2 and half decades ago.
How can I thank you? Seriously, this so helpful!
Excellent
Excellent way..... 👍👍
Thanks alot
Thank u
Best video ever
Me watching this with long QT syndrome type 1: 👁👄👁
Still kicking?
womp womp
Gay
Informative
amazing vedio contineus more vedio
ياسلام عالشرح
حكمت فعدلت فنمت
One of my friends has this!
Best video
WHEN A PERSON IS NICE, THAT PERSON IS ALWAYS REMEMBERED.
Remember always vague but true Indian men?
「あなたの動画はとても良いですし、メッセージがた
Great videos.
However, the script overlay to visit the website obstructs the view of video content. Would be great if it was minimised to a corner of the video or removed completely and posted in the video description for people to view.
Ive experienced palpitations but no chest pain, dizziness or shortness of breath. I wonder if taking prozac has caused this idk
How about what magnesium do to your heart rhythm?
0:39 torsade deeeee pointes
I’ve been having weird dizzy like spells when I get exerted, is this a sign?
How hypokalemia or hypomag. Can lead to arrythmia in long qt syndrome?
Hypokalemia means less potassium in our cells also. So there will be delayed repolarization as repol occurs with efflux of potassium (slower efflux) and hence qt interval will be prolonged . And when qt interval prolonged Early after Depolarizations can occur and cause tachyarrythmia.
Can QT disease go away in newborns? Please answer my question 🙏
Could you please explain why we still have increased heart rate in torsades de pointes since the QT interval is prolonged? Thanks
Prolonged QT is a risk factor for torsade de pointes. Once torsade de pointes happens, there is no more QT, at all - take a look at the ECGs. The details are explained in the video.
In a way it's a way of been hijacked. Once no more qt/repolarization, it's always in a state of depolarization repeatedly/continuously.
Will I die I have this?
Hi I had a question I recently had a ekg test and my qt interval was 452 ms is that normal or borderline?
mine was 437ms
I lost my 4 years old son😢
Is it true that Selective serotonin reuptake inhibitors could cause this condition as well?
Yes, selective serotonin reuptake and many other types of medications can cause QT interval prolongation and sudden cardiac death.
@@brazax7430 I am an alcoholic and I am on citalopram. I am prescribed 40mg a day but I take 80mg a day. The reason why is because I don't feel the full effects, because alcohol dampens down the serotonin levels. Am I still at risk with QT interval prolongation by doing this?
@@innovativeinnovation6629 Patients at particular risk for developing QT prolongation include patients with Congenital Long QT Syndrome, heart conditions and who are predisposed to having low levels of potassium and magnesium in the blood.
Memerlukan lebih ramai orang jadi sebarkan video ini lebih banyak
Huh I don't get a ICD
IN BEING NICE, YOU WON'T REGRET IT.
I’ve been experiencing ( almost ) fainting whenever I work out or do any heavy activity that gets my heart pumping, also chest pain and shortness of breath, heart palpitations etc spooky stuff
sounds like you should see a doctor asap...if not the emergency room
Me too. I would suddenly faint or feel very faint but both after excersise and also just when sat down. I get chest pains and shortness of breath randomly, and I’ve had an ECG which shows I have a long QT.
@@Hanpinky12 did they say why it could’ve happened? I want to say my issues started 7 months after starting an antipsychotic, even after stopping it ( stopped almost 1y 10m ) I still get those weird symptoms but they never saw anything in the EKGs I’ve had
I PASSED THE NURSING BOARD EXAM IN JUST ONE TAKE AT ATENEO DE ZAMBOANGA UNIVERSITY ZAMBOANGA CITY. I THANK GOD MY FIRST COUSIN KARINA LEDESMA DEL ROSARIO, KAIRA LEDESMA DEL ROSARIO, AND CASEY LEDESMA DEL ROSARIO WAS THERE FOR ME DURING MY YOUNGER DAYS, IT'S GOOD, I GREW UP NATURALLY NICE LIKE SERENA VANDERWOODSEN. IF I WAS EXPOSED WITH THE WHOLE FARM WHEN I MET MY FIRST COUSIN KARINA LEDESMA DEL ROSARIO, MY ATTITUDE WOULD HAD BEEN OF REGINA GEORGE..I FORGIVE MY FIRST COUSIN KARINA LEDESMA DEL ROSARIO.
Both are me, with one failed ablation.
GLAD I WAS EXPOSED WITH THE WHOLE FARM LAST JANUARY 2020. ALL THE NICE PEOPLE ARE REMEMBERED.
「どうやってやるの？」、
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IT'S MY FIRST COUSIN LIANNE CRISELDA YU. MARQUEZ WHO IS THE BAD PERSON. I HAVE NO REGRETS IN BEING NICE. I KNOW FLORENTINO S. SUSALO III WHO LOOKS LIKE ENRIQUE GIL COURTED ME BECAUSE I'M A NICE PERSON 🙏🙏🙏 IT'S TOOK A LOT OF MY TIME TO DEPEND HIM. I KEEP ON REPEATING THE IMMACULATE CONCEPCION CATHEDRAL CHURCH ZAMBOANGA CITY. THEN I WORKED FOR ZAMBOANGA CITY WATER DISTRICT TREASURY SECTION AND SO ON.
Wolf Parkinson White?
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💀🫥