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Date of last update: 10/20/2017.

Forum Name: Arrhythmias

Question: Inappropriate Sinus Tachycardia Symptoms (IST)

 Aaron89 - Fri Dec 26, 2008 9:13 pm

Hi DoctorsLounge,

I'm a 19 year old male, and trying to figure out what exactly is wrong with my heart. For over a year (since the night of November 23rd, 2007), I've been having these weird symptoms.

After seeing three (!) different cardiologists over the period, one suggested IST (Inappropriate Sinus Tachycardia). Through further research, it seems incredibly similar to what I am experiencing. My current symptoms are:

* Consistently fast heart rate (~100 BPM) even at rest, although some nights it seems to slow to ~80 BPM.
* Periodic chest pain, sometimes sharp, others constraining and chest "pressure"
* Out of breath most times
* Increased fatigue
* Intolerance to exercise or any type of physical activity, even walking up a few stairs (greatly increasing rate, likely to 140+)
* I ALWAYS feel my pulse/heart beat, and it drives me crazy (24/7)
** With exercise, it's even stronger, and quite scary

Those are the main things. A little prologue: I woke up on the stated date to a very fast heart rate (150+) that night, which would trigger my heart to go fast (like a switch) off and on that week. Once it stayed fast for 24 hours, I went to emerge. They put my on a beta-blocker (Bisoprolol), which had terrible side-effects for 10 days of its use; then I came off from it. Before all of this, I was a relatively healthy individual with a moderately-healthy diet, some exercise (generally in summer months), and a HR of about 60-65 BPM when resting.

Since then, I've had every test under the sun that I can think of, or that's been recommended. Stress tests, blood tests, urine, multiple 48-hour holters, stress echocardiograms, x-rays, and more. I have also checked for a stomach bacteria virus (h.pylori) in desperation. The only thing that was picked up in relation to the heart is a valve that is somewhat "floppy," but I highly doubt that's what's causing these problems. Apparently, I was told 1% of the world's population has it.

My most recent cardiologist has prescribed Propanolol (5 mg twice daily), another beta-blocker, to ease the symptoms. However, I'm reluctant to take it with my past experiences.

As it stands, there's not much I can do. I assume my options are to:

1) Take the medication, and likely a calcium channel blocker (/any other medications), for my entire life.
2) Undergo radiofrequency ablation, something I am not willing to do at this point. This is my last alternative.
3) Try and "live with" the symptoms my entire life, hoping it gets better.

I am scheduled to see an arrhythmia specialist in 3-4 months (it takes long here in Canada), so I'll know officially then. At this point, it looks quite like IST. What's odd is, it seems to be mostly middle-aged women that get this disease (?), me being the opposite.

This is driving me nuts, and SEVERELY affecting my University performance (which is a whole other story). I have officially run out of hope and faith, and have no idea what is causing this. Most doctors that see me refer it to a "Medical Mystery," then simply stop caring.

Any sort of advice, or direction, would be greatly appreciated. I only pray that one has heard of this before, and can guide me in the right path to health once again. Thank you in advance for your time, and I look forward in hearing a response.
 John Kenyon, CNA - Sat Dec 27, 2008 9:45 pm

User avatar Hello -

While the diagnosis of IST is almost certainly accurate, it is often only a symptom and not a proper diagnosis, as there is usually an underlying cause. While everyone you've seen has dismissed the obvious, I'm going to mention it again, anyway, because this fits the picture (as well as a few other things): you mention one exam revealing "only" that one of your heart's valves was "a little floppy." This is known as mitral valve prolapse (MVP), and actually probably more like 10-15% of the general population has it. It is often dismissed as a "variant of normal", but some individuals can have along with it a well-recognized syndrome (MVP syndrome or MVPS), and some people are even diagnosed with MVPS without having the actual prolapse proven (and it can be hard to prove sometimes, since it may appear or disappear intermittently, that "floppiness"). They caught it with you, then totally dismissed it as a potential cause of your symptoms.

Now comes the strange part: no one is really clear as to why people with MVP often develop annoying cardiac-related symptoms, since no one has advanced a convincing theory as to why the floppy valve (we can do away with the quote marks, as "floppy valve" is a clinical term anyway) is usually seen in association with the syndrome. However, it's been recognized since 1963, so it's not exactly a new phenomenon, but some doctors do remain reluctant to recognize the connection, there being no clear-cut cause and effect.

There is at least one major medical center in the US which has a large center dedicated solely to diagnosing and treating this sometimes infuriating problem. It is usually treated with beta blockers, sometimes with radio frequency catheter ablation (although in your case that doesn't seem appropriate based on what you've told us). Again, though, the beta blocker you were first prescribed is not the one of choice for this problem, at least not in the US. Bisoprolol is most often prescribed for control of elevated blood pressure, as it seems to have a greater effect on BP than other beta blockers. While some doctors consider all beta blockers essentially the same, they not only are not, but different people respond to different drugs differently, so please don't allow your bisoprolol experience to color your potential relief of symptoms because of it. That being said, propranolol has perhaps the highest rate of reported annoying side effects (it is also the oldest of the beta blocker family, and is rarely used for the original purposes of blood pressure control and arrhythmia management now. It is, however, probably the cheapest). Metaprolol, preferably long-acting, once-a-day dosing version, is currently the first drug of choice in most practices in the US for problems such as yours. A concurrent calcium channel blocker also doesn't seem to make a lot of sense, at least to me. Further, this is not necessarily something you'll have to take "for the rest of your life" although that seems to be a popular thing to tell people when putting them on certain types of medications. It's almost never true due to the fact that not only do physiological things change, but so does pharmacology and technology. Metaprolol might well be a good starting point for you, though, and if it works and relieves most of your symptoms without causing too many untoward side effects, you could get to like it pretty quickly.

Hopefully the electrophysiologist you will see in a few months will be able to deal with this more appropriately than has been done so far. In the meantime, some suggestions would be: stay well-hydrated (drink more water than you normally would unless you're already a water fan), try to exercise regularly but ease into it and allow yourself to progress slowly. Also, consider what may have been going on in your life at the time of onset of the symptoms, since MVP, which usually announces itself in adolescence anyway, can often become symptomatic after some stressful or traumatic event (physically or emotionally).

Finally, a floppy valve is sometimes actually a "flail" valve, although yours doesn't sound like it. Flail valve means the cord that attaches the free end to the base of the left ventrical is either broken or markedly stretched. This can cause more severe symptoms (and they actually make sense physically) than "regular" MVP. While it really doesn't sound like this is the case here, sometimes subsequent exams will show up things that weren't apparent the first time around, and flail valve is often a discrete physical event. This is very rare, and I only mention it in the interest of being thorough. I don't think this applies in your case.

I hope this is helpful to you. Best of luck to you and please follow up with us as needed. Also be sure to update us once you've seen the electrophysiologist.
 Aaron89 - Sun Dec 28, 2008 3:56 pm

Incredible. Never did I expect such a detailed and informative response. Thank you so much, John.

I was aware previously of MVP Syndrome, but I'm not quite sure I was told the floppy valve was in fact the "mitral valve." If it had been, I'm sure it would have rang a bell. If anything I'll be sure to let you know, if you wish, what the precise valve was called. I believe an appointment with my Cardiologist is in January 2009. If it is MVP Syndrome, I'm less worried that I'll be living with this forever (since there are treatments available), and this so-called "Medical Mystery" may finally be solved.

I also forgot to add things in my original post, like not ever smoking, drinking, or doing any illegal drugs. All these things simply happened ... over night.

Thank goodness you mentioned Metaprolol. I was actually considering taking Propanolol, the new beta-blocker, until you mentioned it had a high rate of annoying side effects; which the main reason for my reluctance. I will hopefully get a prescription of Metaprolol in the future, and pray it eases my symptoms (with minimal side effects). I'm somewhat angered/disappointed that the emergency cardiologist first prescribed Bisoprolol, which as you stated, is generally to lower BP. My BP is almost always normal (and normal that day), except for a few instances where it is slightly low. Likely the reason my body reacted to negatively during that time period.

I am considering radio frequency catheter ablation, no matter how scary it may sound (I'm one you can't even watch these things on TV). If it finally gets officially diagnosed, and RFA seems like the best course of action, I may end up doing it. In your personal experiences, is the success rate as high as they say? Recovery time? I always get the feeling doctors are inflating the success rate when I read stories of those which it was unsuccessful, and are now living with a pacemaker.

Again, thank you so much (!) for your incredible response. Hopefully everything works out alright, and I overcome this obstacle in life. I will be sure to update you/DoctorsLounge once I have seen the electrophysiologist in the coming months. For now, it's all about focusing on school!

Take care, and best wishes!

 John Kenyon, CNA - Sun Dec 28, 2008 5:54 pm

User avatar Hi Aaron,

You're very welcome. This is my area of greatest expertise (and not necessarily by choice, but I do like it), so I tend to get pretty detailed about it. :)

When I read "floppy valve" I assumed right away the reference was to the mitral valve, since one almost never hears the term applied to any of the others, although I'd still very much like to know if thats the one in question. The others are constructed differently, so aren't very prone to floppiness; they instead become narrowed, get vegetation on them, calcify or develop other problems. But we'll see.

I think a lot of "system" doctors try propranolol because it's generally effective and it's cheap but it's also more likely to make one feel lethargic and slowed down for some time before the body finally adjusts to it. Also, while there is now a time-release version, most often it's just prescribed plain, which means taking it 3-4 times per day instead of once as with most of the newer ones like metaprolol. Those newer ones are also less likely to aggravate existing asthma (if that should be a problem for a given patient). It's become the drug of first choice for most doctors treating this sort of problem now, and it's also passed its generic date, so is available at far lower cost than when it went under brand name (Toprol XL) only.

If your tacharrhythmia is, in fact, "just" IST, I'm not quite sure how the ablation would work for you, since it isn't arising from an irritable focus the way supraventricular tachycardia (SVT) or atrial fibrillation (AF) (to name the two most popular paroxysmal arrhthmias) are. Those can be found and burned out via RF ablation, usually with no problem, although as you note, there is the occasional unintended (or sometimes deliberate) ablation of the AV node, which does then require the patient to use a pacemaker for the duration. This is most often deliberate nowadays, and usually to "disconnect" intractable AF, which thank goodness you don't have. IST is usually due to some inexplicable derangement of the autonomic nervous system -- something that happens in various ways with MVPS -- but doesn't have an identifiable "target" area for ablation. Of course the sinus node could be ablated, but then the patient would be pacemaker dependent forevermore, and the heart rate would be regulated that way. It doesn't seem like a practical idea, at least at this time. Your rate would probably be quite tolerable if you weren't so aware of it. Some people aren't. There's no accounting for that, either.

In general, when RF ablation is undertaken for the right reasons, the success rate is very high, although there is the occasional one that just won't work. Those are pretty rare, however. I'm just wondering how that would even fit into your treatment plan.

Again you're very welcome. Focusing on school is a great idea. Hopefully that will help distract you from your heart's shenanigans. Best of luck to you and please keep us updated.

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