Does anyone have what they call Untrue IST? It was explained to me that IST can have many subcategories where either it can be from the Sinus node of the heart, the nervous system, or another arrythmia near the sinus node masking itself. I am asking because my Electrophysiologist and I have for now, concluded that I have Untrue Inappropriate Sinus Tachycardia where my p-waves look a little weird so it may be an arrythmia masking itself as IST. I notice this as well because my heart beats are very strange. It is one thing to have it beat fast but it also beats irregularly (not just PVCs and PACs). Who else has this? Just want to know so maybe we can discuss similar symptoms and give each other some support.
I don't know much about Untrue IST but I do experience to my knowledge just plain sinus tachycardia. Sometimes my heart rate will go from a normal 90 bpm to 110-140bpm for no apparent reason. During these episodes I feel like i'm not getting enough air and am constantly aware of my heart beating in my chest. I'm thin so its easy for me to feel if its beating hard or fast. :( It also seems to take awhile for these episodes to come on and my heart will gradually reach 110-140bpm. Sometimes with these episodes I do notice some PVCs but from my recent visit to the hospital there were no PVCs on my ecg and everything was normal except for my fast heart rate. Though I would swear my heart was beating irregularly. I'm curious have you ever had an ecg done during your sinus tachycardia and if so did it show an irregular heart rhythm? I don't know if this is the case for you but they seem to treat my sinus tachycardia with fluids which always brings my heart rate back down to 100bpm. How do you get your heart rate to slow down? The doctors have't told me wether my episodes are inappropriate sinus tachycardia or appropriate sinus tachycardia but i'm curious to know which it is so I should probably ask them next time I visit the doctor. I have anxiety disorder so these episodes always freak me out which probably doesn't help any to bring my heart rate down. One thing that i've noticed that might help is drinking the recommended 8 cups of water a day which so far has seemed to help prevent these episodes. So if you think you might be dehydrated you might want to try drinking more water and see if that helps you any. I know how scary it can be to have your heart race for no reason and when it happens to me I just feel so anxious like something bad must be causing my symptoms but there never is anything bad going on. I know anxiety can cause fast heart rate for long periods of time so maybe that might be something that could be contributing to your symptoms.
Best of luck and i'm looking forward to your response.
I have many EKGs done and have worn a 24-hour holter monitor before. Everything comes back normal except the fact that I have IST. My heart rate is just fast and with little exertion it is even faster. There really isn't anything I can do to slow it down but continue with the medication they perscribed me Metoprolol 50mg twice a day (occasionally 100mg if I feel like it). I can feel my heart rhythm irregular as opposed to just fast, I can also feel different parts of my chest beating harder too sometimes but the doctors have not said anything. Dehydration does play a role, so I try to stay hydrated. Is your resting heart rate always 90? mine use to be 90-120 resting
My resting heart rate is actually lower then 90 when I am sitting or especially sleeping. It usually hovers around 50-80bpm, more on the 50 side when sleeping. This is mostly because I have right bundle branch block and a bit of the left which causes my heart to beat slower then normal when i'm not experiencing the sinus tachycardia I described. I've had this condition since birth and my doctors consider it a variation of normal. However when walking or doing anything on my feet my heart rate is usually 85-90bpm. I have also noticed that my heart rate is higher then everybody else's while exercising. I'm not sure if this is the same thing as you described but before I get the sinus tachycardia I usually feel my heart beating hard in my chest as if it is beating too hard and then it gradually gets faster and beats less hard but fast. I also noticed that my heart rate increases after eating and come to think of it 4/5 times that i've gotten this sinus tachycardia was after eating not sure if this is the same for you. Judging by your post you seemed to experience IST constantly or did you used to get it in episodes and then return to normal? If drinking more water doesn't work for me I guess I will get medication for it but I was hoping I wouldn't have to take it everyday just every time I get the sinus tachycardia not sure if doctors offer that or not.
Also just wondering did the Metoprolol get rid of your IST?
Metoprolol brings down my heartrate about 10bpm. Yeah like most people diagnosed with IST we all have IST 24/7, it seems like your situation you only get tachycardia with exertion. I do not have IST episodes since it is a 24/7 episode you can say but I do get PSVT episodes when my heart rate hits 200+ then beats back to normal after one regular beat.
Yeah it seems we have two different problems however I do get the tachycardia without exertion and those are the most scary episodes which usually result in me visiting the hospital to get it to stop. I can't imagine what you must be going through to have that 24/7 it must be hard and I hope you find some better relief or at least someone on this forum with the same problem to talk to. Best of luck to you and if you have any questions about anything feel free to send me a message.
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