My Broken Heart – an Explanation of IST

A lot of people have asked me questions about my disorder, because even my nurse friends have never heard of it. One of my aunts recently asked me if there was somewhere on the internet she as someone who doesn’t know much about medicine could go to learn about my heart problem.

Surprisingly, the answer is, not really. The information that is available through a simple google search is primarily from 2003 and before. It is both outdated and flat-out wrong according to more modern research. As a health care professional, I had access to the most current peer-reviewed journals and research, and I still am not quite sure what to tell people about my disorder. The problem is, there aren’t enough people who have it for there to be good, solid research on it. One of the major midwest clinics that specializes in rare disorders did a two-year study on IST that they published. In two years, they saw 9 patients with the disorder and a handful more who qualified but were unsymptomatic.

You see, this disorder has been documented for a very long time, but it is still not well understood. It wasn’t given its current designation until 1979, when it was labeled Inappropriate Sinus Tachycardia (IST). It generally becomes symptomatic in women aged 20-40, and seems more prevalent in women who work in health care.To explain what it is, I’ll have to go into a bit of a lesson about the “normal” rhythms of the heart. Bear with me.

Sinus rhythm is the rhythm most people are in most of the time. It is the “normal” baseline. Sinus rhythm means the atria are firing before the ventricles to efficiently push blood through the system, and that the rate of beating is between 60-100 per minute.

Sinus tachycardia happens when the heart still beats in the right pattern, but the pattern speeds up. 110 beats per minute, 130 beats per minute, 140 beats per minute. This can push into another rhythm known as supraventricular tachycardia or SVT, which basically means everything above the ventricle can’t beat fast enough to keep up. The heart can beat as fast as 150 to over 200 beats a minute in this rhythm.

Wait a minute… sinus tachycardia can be normal though, right? Correct! Sinus tachycardia is perfectly normal in certain situations. Like when you exercise heavily. Or when you have an adrenaline rush in a situation of danger.

The trouble with IST is that sinus tachycardia happens when it is NOT normal (when it is inappropriate). When sleeping, sitting quietly in a chair, standing up, walking slowly to the bathroom, driving a car, playing a video game, reading a book, watching TV… you get the idea.

IST is characterized by an elevated heart rate all or most of the time, with spikes of the heart rate well over the “normal” range during very mild exertion, very mild stress, or even just being irritated by some dumb kid on the internet. The elevations in heart rate are prolonged and difficult to control with medications. They lead to severe chest pain, nausea, dizziness, lightheadedness, syncope (passing out), and palpitations (you can feel your heart beating forcefully as if it’s trying to punch its way out of your chest, or maybe doing some flip-flops for fun in there).

Consider that the “target” heart rate for an average person doing a 20 minute exercise routine for heart health is somewhere in the 120-130 range. Then consider that folks with IST have a heart rate in that range or higher for hours and hours a day. Even when they are just sitting in a chair doing nothing. It takes an enormous amount of energy to run the heart that fast, and leaves you feeling fatigued, drug out, and emotional.

IST is not caused by anxiety (it was ruled out), thyroid imbalance (also ruled out), or any other hormonal or emotional problem. I’ve had six months of extensive testing, some of it invasive, and all of it difficult to endure. My cardiologist says this disorder cannot be faked and that all other possible causes have been ruled out in my case. My endocrinologist and sleep pathologist and general practitioner didn’t know what it was until I explained it to them. Yeah, it’s really that rare.

The current research and guidelines on IST say that there are three treatment options.

1) A drug class called beta blockers – these slow the heart. They also cause severe side effects in many people, including low blood pressure, passing out from low blood pressure, severe depression, and in men, impotence. My doctor has tried several of these, including metoprolol, inderal, and bisoprolol. The first two caused depression and fatigue so severe I stopped caring for my own needs. For a couple weeks at a time while trying to adjust to the meds, I rarely showered, missed 1-2 meals a day… even brushing my teeth was just too much work. I became suicidal, but fortunately didn’t have the energy to act on those thoughts. Bisoprolol, so far, is only causing low blood pressure and more dizziness, to the point that it is no longer safe for me to drive a car.

2) Calcium channel blockers – these also slow the heart by working on one of the molecular pathways that allow electrical signals to flow smoothly and quickly along the heart. They have been shown to be effective in a small percentage of people with IST, and they come with a host of side effects of their own.We tried this one, too. Cardizem caused me severe and continuous chest pain. For about a week, I felt like an elephant was sitting on my chest. It was hard to breathe, and I couldn’t even walk to the bathroom without assistance toward the end.

3) Surgery called ablation for cases that are very severe and which cannot be controlled with medication. The surgery was once thought to be a complete cure, although symptoms persisted in many people despite having a clinically measurable lower heart rate. The ablation surgery carries risks of damage to the nerves that control the diaphragm (ie breathing), perforation of the heart, inadequate destruction of the electrical initiation cells (SA node) of the heart resulting in a need to repeat the ablation (sometimes over and over again), over destruction of these cells resulting in too low a heart rate and the need for a pacemaker. Further, the SA node can grow back, requiring the surgery to be repeated in 3-6 months, even if it looked completely successful. The surgery also carries the risks of death, brain damage, stroke, and further disability. The risks are considered moderate for most people, but surgeons hesitate to place a pacemaker in someone my age. Pacemakers have risks of their own, including massive infection, dysfunction of the machine, frequent need to monitor and recalibrate the machine, and the need to replace the machine every 5-7 years. My doctor has talked about this as an option for me. He thinks it might help. The risks and long-term complications (like a pacemaker) have to be weighed against my daily life without the surgery, though, and the only person qualified to make that decision is me.

IST is not life-threatening. It is not going to shorten my lifespan. Very few people who get IST progress to any sort of heart damage even after years of elevated heart rates. My arteries are clear. My muscle works fine.

Knowing that, knowing that I will not die from this disorder no matter how much it changes my life, makes facing the risks of repeated surgeries and implanted devices seem unwise to me. The truth is I am here today with my husband and my son. I can still type, read, write, sing (if a bit breathlessly), cook a meal (if I pace myself), and enjoy spending time with my guys.

Yesterday, I was playing an online game and a 15 year old kid said something to me that kind of ticked me off. Not “blow a gasket” pissed off. Just sort of annoyed. I could barely speak for the palpitations. My heart rate was over 140. My hands were shaking so bad that I couldn’t type the reply my brain was cooking up. I am not a docile person. My wit is sharp and my tongue has been known to be even sharper. I turned off the computer and sat there staring at the screen. I could not walk away, for fear of falling on my face. It took over an hour for me to start feeling “normal” again enough to get up and walk around.

Life with IST isn’t easy. I could waste my energy railing against how it isn’t fair (it isn’t), or how I wish it would just go away (I do). I could just follow through with one of those suicide plans I thought up while on the depression-inducing beta blockers.

But I’m not a whiner. Or a wisher. Or a quitter. I’m just me. Fast heart and all.

UPDATE: So many of you have expressed thanks for this post and asked after me over the years since I wrote it that I felt an update was in order. You can find more information about how I’m doing now (2013) here.

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75 Responses to My Broken Heart – an Explanation of IST

  1. Crystal says:

    Thank you so much,this has been most informative piece of info I have found.i am in early stages,wore 48hr monitor getting ready to start 30day monitor for definitive diagnosis. Thanks again

  2. Vanessa Atilano says:

    Thank you for this. My cardiologist said that it’s most likely inappropriate tachycardia. It’s been hard feeling and knowing something is wrong but no one telling me what is wrong. I get so rattled up sometimes no willfully and its so hard to calm down even when I’m not upset. My finger tips and hands get soaked from me sweating. I hope someone can give me answers.

  3. Megan C says:

    Thank you for writing this. You literally put into words Exactly how I feel! I’m 27 and was just recently diagnosed this year. I went to at least 4 different cardiologist and an electrophysiologist before I was given a reason for my rapid heart rate at odd times. The worst is when your scared or angry and it sky-rockets… Hands start to tremble, sweating, nauseous. Most people don’t believe me and think it’s all just stress or anxiety related. It’s so nice to know other people are going through it too. I wish I could find a local support group to reach out to!

    Thank you for sharing your story!

  4. September Stone says:

    I cried reading this. I’m so thankful for the information. I haven’t been understanding what has been going on with me for months. I knew “something” was. I just couldn’t figure it out. Months later I am now in my first week of torture taking Metoprolol.

    Thank you so much!!!

  5. Arizela says:

    September – I’m really glad you found this helpful. Good luck to you!

  6. Katherine says:

    OMG I’ve been under investigation for over 2 years and everything you have said here just clicked straight away for me. I had ablation in the summer of 2014 for AVNRT, which they only found after electrophysiology, it seemed to have done the job but by late sept. the tachys and ectopics were back. Because all the results are Sinus tachy they’re adament theres nothing wrong but I know there is, after all I’m the one living with it. Next time I see them I’ll be asking about this and hopefully I’ll get the right answers. Just been given Bisoprolol hoping I don’t get these awful side effects, fed up of the whole thing now. Thank you so much for putting this out there. Hope all is well with you

  7. Kristin Healey says:

    I absolutely love this article and thank you so much for writing it. You put into words exactly what is going on with me. It is terrible and very hard to live with. And nobody ever knows what it is!

  8. Carolyn says:

    I’ve just been diagnosed with IST too. I really relate to all you write. In my case I get a very sharp spike in heart rate after cooling down from exercise. My heart rate might be at 120 during a brisk walk, will slow to 90 two minutes after slowing down, but then jump to 140 all of a sudden when I’ve stopped. Does this happen to anyone else?

  9. Jennifer says:

    I am a 41 year old mom of three and suffer from both IST and SVT, along with the daily flip flops and flutters of PVCs and PACs. It’s a really crappy way to live and I can’t believe we have no other options – drugs that may or may not work (I’ve tried toprol which made it worse, acebutolol which stopped working, verapamil which also stopped working, and am now trying a combination of propranolol and verapamil at low doses). Then there is the risky ablation procedure, which also may or may not work. I wonder if this is hormonal. Mine seemed to get markedly worse after the birth of my third child when I was 39. I had the issue for years, but was told it was “panic attacks” although I wasn’t anxious and my heart would surge up and down from 100-160 for hours at a time, making my chest sore and making me fee like I might pass out.

    My episodes also seem to happen most frequently at night, like when I wake up from sleep to use the bathroom or brush my teeth or take out my contact lenses. I get a sudden tingly feeling, weird sensation in my chest, I get some kind of rush or surge of heat or adrenaline and BOOM my heart takes off. Even with the meds it can hit 150-160 and I can’t stop it. This has been documented time and time again as sinus tachycardia.

    My doctors and electrophysiology doctor all say it’s not life threatening, but it sure feels that way when I wake up from a peaceful sleep and my heart feels like it’s running a sprint. I would love to get in touch with anyone else who suffers from this. We need to support one another!

  10. Chelsey Phillips says:

    I was so glad to come across this article. It’s nice to read something that is easy to understand and isn’t full of medical terms. I was diagnosed with IST yesterday after having difficulties and being told it was just anxiety. After the medicine prescribed for anxiety didn’t help, I pressed the issue further and visited a cardiologist and found out what has been going on with me. Have been on altenolol and it’s already helped tremendously.

  11. d davis says:

    I have IST after catheter ablation for avrnt I’m miserable it’s hard to drive dizzy all the time feeling like I’ll pass out getting sweaty I’m on 160 mg propranolol er still not helping

  12. Debra Davis says:

    I have IST after catheter ablation for avrnt its hard to drive always dizzy and sweaty I’m on 160 mg propranolol er still don’t help

  13. June says:

    I’m so thankful I found this site, I’ve been dealing with IST going on 5 years, and it never gets easier and still very scary. My question to any of you is during these attacks does your heart rate keep going up and down like a roller coaster. I also have fibromyalgia which make everything worse. Thanks for listening.

  14. Patricia chatterjee says:

    I have had ist for twelve years. I finally, after months of testing, found a cardiologist who made the diagnosis and put me on toprol. which has worked well. It took me two years to recover from the chronic fatigue and other weird symptoms caused by the the tachycardia. I also don’t discuss it much because people suggest I am am either suffering from depression or anxious which I am not.
    Recently I had another episode early one morning and had to go to the emergency room. I had a follow up with a cardiologist who wondered if I wasn’t just anxious. Unfortunately, the cardiologist who made the diagnosis has died or 1 would have called him. Things have settled down again, but I intend to look for a cardiologist who knows what this is

  15. Sandy says:

    I have inappropriate sinus tachycardia, it has taken 1 1/2 years to diagnose 4 cardiologists and three electrophysiologists. Beta and calcium channel blockers did not work. Be persistant, don’t wait to be referred, I kept looking until I found the university of Washington medical center. They figured it out, put me on corlanor. It is like magic! My resting heart rate was between 110-140 with peaks to 240bpm. I also have right and left bundle branch blocks and occasional 1st degree heart block. Now with corlanor my heart rate is 62-78 bpm. No more chest pain, palpitations, SOB and the fatigue is reducing by the week. I highly recommend University of Washington medical center!

  16. Lisa says:

    I have recently been diagnosed but have been long time sufferer. I was a nurse and has never heard of this. And since I look well, most folks think I’m not really ill. This has been the absolute hardest part of this….the experience of not being believed by fellow healthcare workers and socially. It has been demoralising. And the fatigue and near syncope have me scared and not driving. I’m a single mom of two. Are there any resources for us? I am due for my DO next month and can’t work like this. This should qualify for orphan disease status! Please contact me with any info or support. My symptoms were as previous players mentioned but also gi and a sucking feeling in my abdomen. Waking in a sweat, riddled and wired. Was dismissed as anxiety on many occasions although I wasn’t anxious. I can’t afford to be this dysfunctional and disbelieved.

  17. Vicki says:

    I too was diagnosed with IST a month ago. I am on corlanor as well and I am back to work and sort of normal. I could not tolerate beta blockers (bad bad memories) and new research suggests these are not useful for dysautonomia patients. I am still fearful of the future, corlanor is expensive for off label use, and don’t want to be on meds my whole life. I guess we just have to live one day at a time. Glad I found this thread, I feel less alone. Best wishes to everyone.

  18. Jae says:

    I have IST. It has been a long, grueling process trying to figure out what it was, but Mayo Clinic finally confirmed that it’s IST. I relate so much to this article and especially to what others have said about how difficult it is to get a diagnosis and having people telling you it’s anxiety or depression. During the 2 years I was experiencing terrible symptoms (dizziness, fast heart rate, fatigue, headaches) doctor after doctor told me that it’s anxiety or depression even though I kept insisting that I was not anxious or depressed. One doctor even wrote in his notes that I was just your typical “white suburban teenager”, all angsty and depressed and all that fun stuff. It’s just been such a scarring process, having to be accused of all these things and even having doctors criticize my personality (calling me “blunted, unemotional, too quiet”) and assuming that since I’m not your typical bubbly person that there’s something wrong with me psychologically. Now every time I go to the doctor I feel like they’re secretly judging and scrutinizing me. We all honestly need a support group or something, where we can talk to other people with this condition who can actually understand what we’ve gone through.

  19. Arizela says:

    Hi, Jae.

    I’m truly sorry to hear that you are having those issues. Please try to keep in mind it’s the ignorance of your providers that is to blame here. There is nothing wrong with being quiet or appearing outwardly unemotional, particularly given the frustration, fatigue and uncertainty of having an illness people tend to dismiss or mischaracterize.

    Best wishes to you,


  20. Valerie says:

    THIS IS MY LIFE!!!!! I woke up a few months ago with a suddenly racing heart. Ive had cardiac tests, have worn a monitor, bloodwork, etc. The palpitations(pvcs) are horrible. Sometimes they hurt.. sometimes they’re so uncomfortable coming every other beat. I am/was so afraid that I was going to die. I have two little babies and Im terrified. I feel a little more at ease knowing you’re okay and living with this. The meds suck. They drop my BP. We have discussed ablation, I have such severe anxiety that I don’t know how I would get thru it. Plus Im afraid Ill die….. So I guess this is my life…. for now!

  21. Marsha lee Barnes says:

    thank for this my mom has being suffering from this and m so scared she wakes up at night because of the pain in her chest and it’s being stressing me out glad to know its not life threatening but am still scared she ent to a doctor got some pill to take after they diagnosed it she said it help a bit going back to the doctor think it’s gotten worse

  22. Mark S says:

    Hi, this thread is pretty much on point with my symptoms. Aside of being male, I work in health care and suddenly in my early 30s developed a tachy……palpitations, tired, exhausted, periods of insomnia and sometimes hypertension.

    I have a great cardiologist and a fantastic EP, between them all ECG, bloods, x Ray, Holter, stress echo and CT coronary angio are normal and they diagnosed IST. Verapamil was ghastly but I get good effect 90% of the time on metoprolol and have been able to return to work etc…….. Cardio has suggested Ivabradine (corolanor) but I’m apprehensive to cease the beta blocker as it seems to be working most of the time….

    Any thoughts?.?

  23. Janet says:

    I too was losing my battle with severe rapid heart rate, not being able to sleep with a resting heart rate of 130 bpm. I could not function at work, or enjoy the things I loved to do. Severe depression was setting in as I had lost my drive to enjoy life, until I found a cardiologist who wouldn’t give up on me…. finally!. I am now on Corlanor twice a day and it has been a complete lifesaver for me.

  24. Natalie says:

    thanks for sharing your story i am 25 very fit and healthy i was diagnosed with stage 3 chronic kidney disease when i was 23 i do not smoke and rarely drink i have went through every test possible to find out why and the doctors still cant find a cause for this while being tested doctors noticed my resting heart rate has been 135bpm through this time i wasn’t aware of it but when i told the doctor the symptoms i kept ignoring it just thinking that i was just low in iron or something and i had mentioned that my room is in the loft and i was about to come down my ladders when an episode hit everything went black my heart felt as if it was beating so fast and i fell out my loft i tried to grab on to the ladder to stop my self falling but just happend so fast i was very lucky i never landed on my neck just a few scrapes and bruises and a bump on the head so this year i have been getting a lot of test with the cardiologist and they said i also have IST i have been told of medications but i am waiting to find out whats the next move as i was leaving to work in greece for the summer so i said i would deal with it when i came back i was made aware of the side effects of the drugs and that it dosnt always work so i am going to tell them that i will hold off treatment unless it gets much worse and i can know longer cope with the symptoms then i try treatments.

  25. Jenn says:

    Seroquel brought on heart palpitations and difficulty breathing out of the blue. I was told to switch medications, but that was a complete nightmare. I was put on Metroprolol Tartrate, but that didn’t control my symptoms. I was then switched to Metroprolol Succinate. Symptoms got better but did not completely resolve. I went in for an ablation, which couldn’t be performed because I was then diagnosed with IST in the heart lab. I was offered Corlanor and told about a surgery that could fix my IST but was risky. I chose to try Corlanor instead. It made a tremendous difference for me. I take it daily and take a little bit of Metroprolol Tartrate if I do notice breakthrough palpitations and difficulty breathing.

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