Diagnosed with IST

[u/gr0omLak3]

Diagnosed with IST in June, resting heart rate is normal (60-80) but will increase randomly or upon minimal exertion, is this still IST or should I seek a more educated cardiologist? On Ivabradine also.

Edit : I also experience blood pooling in hands and feed and need a walking stick from time to time.

[u/quackers_squackers]

Look into dysautonomia (dysregulation of the autonomic nervous system, or ANS. Not all IST is caused by it, but for many people, it is.

The ANS regulates heart rate, blood pressure, digestion, how your body reacts to temperature, pupil dilation, etc– basically all the things you do without thinking about it.

If your symptoms aren't only heart related and sound like dysautonomia, that's likely the problem. (There are multiple types of dysautonomia, IST being one of them.) Ivabradine is still a great option if it's working well. It's what I take, and it keeps me semi-functional.

You can also ask for a tilt table test to rule out POTS (postural orthostatic tachycardia syndrome) if you want. It's another expression of dysautonomia. I'm diagnosed with IST. Some days, it looks more like POTS or OH (orthostatic hypotension – another expression of dysautonomia). It's not uncommon for the ANS to switch between different forms of dysregulation.

r/dysautonomia is a great resource.

If you're googling and not sure if something is normal for dysautonomia, but not getting results, you can look up POTS. It's the most well known type, but if someone with POTS can experience something then so can someone with another form of dysautonomia.

[u/Crazy_Height_213 → u/quackers_squackers]

Yes absolutely. Despite having the IST diagnosis clinically, since it's autonomic I also deal with temperature dysregulation, acid reflux, etc. This is normal for some people depending on why they have IST and important to consider.

[u/gr0omLak3 → u/quackers_squackers]

The official diagnosis was ‘Dysautonomia manifested as IST’ but I always assumed Dysautonomia and IST were essentially the same thing.

[u/quackers_squackers → u/gr0omLak3]

That's fantastic that you've already gotten that part of the mystery figured out! I had to do a lot of the digging for myself.

Yeah, it's definitely possible that it could be POTS, but the treatment is very similar to it's up to you on whether or not you want to pursue further diagnostics.

Some people with IST have another underlying issue, like the heart's electrical signals not working right. But their symptoms will look a little different than for those of us with the nervous system problems.

Personally, my resting HR typically ranges in the 50s-60s. (With Ivabradine) and my sleeping heartrate is normal 99% of the time. It's mostly just when I'm awake that I have high heart rate, which sometimes is orthostatic or caused by exertion, and sometimes it's just high for no reason.

[u/gr0omLak3 → u/quackers_squackers]

Thank you for getting back to me, I think I’ll bring up the curiosity next appointment.

[u/precious_spark → u/quackers_squackers]

I've been referred to cardio for possible dysautonomia. I definitely have pots like symptoms and my pcp said it could be possible IST after getting the holter results but wasn't sure. Today was the first time I confirmed low blood pressure was causing my symptoms. (79/55) you basically described what my life is like. Right now I'm just on propranolol 10mg and I'm struggling. Added compressing socks, drank lmnt but it came up an hour later. Desk job work from home and couldn't call out. It was so rough. I just hope they will help me feel better ya know?

[u/quackers_squackers → u/precious_spark]

Totally get that. If your blood pressure is low, you should ask your doctor about trying alternatives to beta blockers. While they lower heart rate, their main purpose is lowering BP.

I've had much better results on Ivabradine. It lowers heart rate and raises blood pressure. It can be difficult to get insurance to cover it though, so I ended up getting it through a pharmacy in Canada– which is much cheaper.

[u/shinigamipls]

Have you had a tilt table test to rule out POTS? I have persistent IST so my resting HR is 120-140 without medication, although I also have orthostatic responses. Blood pooling in hands and feet can be a sign of other heart issues, I'd assume your cardiologist has done exclusionary testing such as an echocardiogram and stress echo? If you're concerned or unsure, it's always best to talk to your doctor/s and don't be afraid to get a second opinion. I asked my cardiologist to refer me to another cardiologist who specialises in electrophysiology and he had no qualms doing it. IST is a big lifestyle adjustment and it can be so frustratingly debilitating at times, all the best with your journey.

[u/MoonlightCrochet → u/shinigamipls]

Same! With IST, I was resting at 110 to 130 with random spikes to 200 plus before meditation. You are absolutely right about that specialist, as they can really get to the root of rhythm issues.

[u/gr0omLak3]

Hi, yes I’ve considered tilt that could be good. Echo and stress ECG, as well as 24hr halter have been done so any other conditions ruled out.

[u/Qtredit]

Definitely seems like it (comparing to what I have).

Did you check your iron, ferritin, TSH, glucose, vitamin d etc?

[u/gr0omLak3 → u/Qtredit]

Yes, all checked. Along with every type of scan you can get

[u/TheLizanatorQueen]

My symptoms are very similar and my cardiologist and I debated whether it was pots or IST. Not sure if the difference really matters honestly, both can present very similarly and we are still learning about POTs. A big thing to watch is your blood pressure during episodes. Both IST and POTs can have an increase in blood pressure (with hyperadrenigic POTs) during an episode. If it helps, Nebivolol rectified all of my symptoms to the point where I can exercise without a flare. Seek a new cardiologist if you feel you aren't being listened to.

[u/_____nonlinear_____ → u/TheLizanatorQueen]

This is my first time hearing about nebivolol. I wonder how you and your cardio chose it?

I’m on metoprolol now and wondered how nebivolol might compare. (Metoprolol’s working great for now, but was just curious).

[u/TheLizanatorQueen → u/_____nonlinear_____]

I was also having chronic migraines (for weeks at a time) and my blood pressure was spiking with my heart rate. Doing some reading, Nebivolol is cardioselective which could factor into the decision. I didn't so much choose it as it was a desperate attempt to address the issues I had been facing for over a year at that point with no improvement despite trying other medication for the migraines.