5 ms·
Excitable cells
- samwho 2y agoAbsolutely fantastic. Well done!
- Kalabasa 2y agoLearned about the heart today! Thank you! I wonder what other types of cells / tissues can be simulated by cellular automata?
- owenpalmer 2y agoI was thinking the same thing. I need more simulations like this!
- danwills 2y agoDefinitely have a look at gollygang/Ready I reckon! There are some really fascinating things in the pattern library (including some that I contributed). https://github.com/GollyGang/ready https://github.com/GollyGang/ready
- danwills 2y agoI think many types can if you broaden the definition of automata to include 'reaction diffusion' you can even simulate things like the Schrödinger equation under a RD scheme! (there are some examples in gollygang/Ready). RD was invented by Alan Turing as a way to model animal coat patterns too, and I think it's exceptionally good at that (I did a talk at Houdini Hive SiggraphAsia2019 about it: https://youtu.be/K_7TkoIkFhk?si=afhcjZ8TeysNJxRH https://youtu.be/K_7TkoIkFhk?si=afhcjZ8TeysNJxRH)
- agumonkey 2y agoAnybody know similar article but about blood flow / hemorheology ?
- lofties 2y agoExcellent article! Well written and the animations make it so much easier to understand. However I was unable to get the loops to go.
- samwho 2y agoI was able to do it by clicking in a few places in quick succession evenly spread out.
- jcattle 2y agoTry clicking in one place repeatadly and adjust clicks slightly to always go next to the fastest refractory cell possible. This works like a charm to induce arrhytmia
- leereeves 2y agoI was able to consistently start a loop in one click by clicking on the edge between grey and white (slow and fast refractory) cells ASAP after a normal beat. If I'm fast enough, the wave can't spread to the grey cells so it only goes in direction around the red cells and starts a loop. (But you can't do this on the first image with a Defibrillate! button because there are no slow cells.)
- EncomLab 2y agoAs someone who lives with this reality moment to moment (thanks to a deeply bridged LAD coronary artery) it is interesting to see a visual representation of these effects.
- pscanf 2y agoExciting simulations! :) And an excellent explanation. From time to time I get episodes of sudden tachycardia¹. It's a very strange feeling: one second everything is fine, the next my heart jumps in my throat and starts beating at 230 bpm (not a typo). After a while, just as quickly as it came, the tachycardia goes away and I'm back at whatever HR I was before the trigger. If it doesn't go away by itself, breathing in deep and holding my breath typically does the trick. It's like a light switch! A bit scary, but also very fascinating. Thanks for explaining so well what goes on "under the hood"! ¹ https://en.wikipedia.org/wiki/Paroxysmal_supraventricular_tachycardia https://en.wikipedia.org/wiki/Paroxysmal_supraventricular_ta..., I believe.
- papascrubs 2y agoI have a similar condition. Mine is: https://www.mayoclinic.org/diseases-conditions/wolff-parkinson-white-syndrome/symptoms-causes/syc-20354626 https://www.mayoclinic.org/diseases-conditions/wolff-parkins... I have the same bouts of tachycardia. They are very intermittent, no real cause. And the same breath holding technique works for me. Very interesting stuff!
- papascrubs 2y agoI have the same condition. I was diagnosed at a very younger age with Wolff-Parkinson-White syndrome. It might be worth looking into. https://www.mayoclinic.org/diseases-conditions/wolff-parkinson-white-syndrome/symptoms-causes/syc-20354626 https://www.mayoclinic.org/diseases-conditions/wolff-parkins...
- limaoscarjuliet 2y agoWith WPW you MUST NOT take beta blockers (AFAIR), it may kill you. I had just plain vanilla Afib and got ablation 2 years ago - best thing ever, cured instantly.
- pscanf 2y agoFortunately I don't think it's WPW in my case. Or at least, my cardiologist never mentioned it, so I assume it's some other condition that has similar symptoms.
- leereeves 2y agoI love this article. I had already learned all the facts in the article, but even so, the interactive animations helped me understand it better. Thank you.
- eknkc 2y agoI have frequent ectopic beats that I feel as a flutter / heavy beat on my chest. The doc says it won't kill me but it is extremely uncomfortable at times. This has been a great material to learn about the inner workings of heart cells. BTW Here's an ECG from my Apple Watch showing 3 such beats (you can't miss them): https://link.ekin.dev/l1Vc3Gdf https://link.ekin.dev/l1Vc3Gdf If you happen to have these, just get checked out by a cardiologist. They are almost always benign but the frequency / daily amount are reasons for concern.
- elric 2y agoMany (most?) people get ectopic beats, but the threshold for noticing them seems to differ. Being stressed/anxious makes them more noticeable. There's a self-reinforcing feedback loop: the more you notice them & worry about them, the easier you will notice them ... The thing about arrhythmias is that they can only cause damage while they're happening, but ectopics are only a problem for a single beat, which is not going to impact your oxygenation or blood pressure or anything else. Even a bunch of them every day won't cause any damage.
- UncleOxidant 2y ago> Many (most?) people get ectopic beats, but the threshold for noticing them seems to differ. This. Some of us have very high levels of proprioception. I can feel my pulse just by sitting quietly - I don't need to put my finger on my wrist to take it. Same with ectopic beats, I definitely feel them. And I find that there's a cycle to it - as you say there's a feedback loop: feel ectopic beat, become anxious, more ectopic beats, more anxious, etc. Then I have to try to actively forget about them. During those feedback times I'll have many ectopic beats / day (many per hour, even), but then some days later I'll realize I haven't had any for a while and I might go for weeks without noticing any.
- eknkc 2y agoApparently everyone gets them but the burden (% of beats being screwed up) is important. A high burden for prolonged periods means damage accumulation. I had 2 24 hour monitors and one caught 700 eptopic beats in a day. Another couple months later, 15.000 in a day. The second one was a concern for the cardiologist. She ordered a couple more tests, started beta blockers asked for diet changes. I still have a high burden as I can feel them but whatever..
- the_arun 2y agoTrying to understand Author’s education. Have they done both Medicine & Engineering? Looking at their articles & github, they are sound in electro physiology, Anaesthesiology & software. Great intersection of knowledge.
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- mjamesaustin 2y agoI don't know the author, but I will note that my cardiologist got an Electrical Engineering degree before going to medical school and views it as a huge advantage when dealing with the heart.
- johannes_ne 2y agoThank you all for the interest in the article and the kind feedback. I'm a medical doctor with an interest in engineering and coding. My PhD was quite focused on signal analysis and coding, and my supervisor is a medical engineer.
- fraserphysics 2y agoI am reworking the analysis of ECGs from an old contest, and I want help from an expert. In 2000 the Computers in Cardiology challenge (CINC2000) provided ECGs from sleep studies of 70 patients and asked contestants to identify obstructive sleep apnea based on those ECGs. I was on the team that won. Now I am reworking the problem for the second edition of a book (see https://www.fraserphysics.com/book.pdf https://www.fraserphysics.com/book.pdf), and I see great variety in those ECGs (see https://www.fraserphysics.com/all_ecgs.pdf https://www.fraserphysics.com/all_ecgs.pdf). I suspect that some of that variety is due to lead placement, and some is due to pathology, but I'm not sure. Is anyone here willing to help me out?
- dheera 2y agoOh this is interesting. Thanks! I've survived ventricular fibrillation 3 times and have an implanted ICD. I never really understood why delivering high voltage shocks is that effective, and always have anxiety about "the time it won't work"
- mjamesaustin 2y agoAs someone who had their life upended last year upon discovering I had AVNRT, this article is much appreciated. I'm still trying to understand the root cause of my arrhythmia, because two ablations and one daily medication later and I still have regular episodes. It's wild how many different types of arrhythmia there are, and how they can be connected to many other systems in the body. It seems like mine might be related to my nervous system.
- PaulHoule 2y agoI'm rarely intimidated by a textbook but I was intimidated by a set of cardiology books I saw at the vet school. The topological structure of waves in the heart is https://en.wikipedia.org/wiki/Spiral_wave https://en.wikipedia.org/wiki/Spiral_wave because cardiac cells circle around a loop with phase from 0 to 2π, contrast that the usual oscillator which has position p and momentum q. An oscillation in that space can rotate around the center and look like a phase but it's also possible to go right through the center, whereas for cardiac excitations the p variable is on the unit circle. This astonishing book covers the topology of this kind of thing: https://archive.org/details/geometryofbiolog0000winf/page/n9/mode/2up https://archive.org/details/geometryofbiolog0000winf/page/n9... particularly the cases where you have just one phase (e.g. jet lag or cell division or plant phenology) but it applies as well to those spiral waves where every element in the medium has a phase.
- randerson 2y agoI had a benign irregular heartbeat (Premature Ventricular Contractions) for half my life. During one checkup the cardiologist said my heart had become enlarged to compensate, and if I wanted an energy boost I should get an ablation surgery. The ablation was quite the experience as I was kept conscious throughout (and I felt euphoric thanks to the painkillers). A team of students carefully threaded a wire in through my femoral artery, guided it up to the inside of the heart and zapped the problematic cells. I could actually feel the moment they fixed it. One moment my rhythm was irregular, the next it was regular. They then ran a series of stress tests that included injecting me with something that pushed my heart rate above 200 bpm. That was uncomfortable. I was back to my normal routine 24 hours later and I did indeed have more energy.
- johannes_ne 2y agoThank you for all the kind responses. I also want to make a similar article, where I calculate an ECG for the simulation, and then make and explain the changes necessary to make the ECG look realistic. A main challenge will be that the depolarization has to happen very fast relative to the repolarization, which may be computationally difficult for a cell-based simulation.
- fraserphysics 2y agoAlso cool would be the inverse. Going from ECG to plausible simulated RD dynamics.
- johannes_ne 2y agoIndeed, but that problem is just so much more complex.
- BenFranklin100 2y agoOff topic, but I’v always wanted to download web pages like this that contain interactive plots for self-study or later reference. Solutions like SingleFile or Zotero never work though. Any suggestions?
- bobowzki 2y agoTitle reminded me of Tubular bells.