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Avatar universal

What causes inappropriate sinus tachycardia to begin in the first place?

I am a healthy 37 year old woman, who went through surgical menopause two years ago. [Other than many repeated viral illnesses in the past six months] I am at an ideal body weight, I exercise 3-4 times weekly, and I don't smoke.  I take Premarin and progesterone daily.

This past winter, after suffering a fairly severe flu, I began to experience what has been diagnosed as inappropriate sinus tachycardia for the first time.  For the 37 years prior, I never had any cardio issues whatsoever.  Then I suddenly began to experience unexplained bouts of rapid heart beat and shortness of breath.  At first my symptoms abated when I increased my estrogen replacement, only to return again in a more severe form about two months later.  I began to have bouts of rapid heart beat and "skipped beats" daily from about 1:00 to 3:00 p.m. -- bothersome enough to prevent me from being able to do anything, with a BP of about 150/95 during these episodes.  Advice to just ignore it really wasn't helpful -- I was too short of breath during the episodes to be able to really function.  Chance in diet, relaxing, completely avoiding caffeine, alcohol, etc. made no real difference.

I have run the gamut of tests, holter monitor, echocardiogram, stress tests, VQ scan, blood work, pheo testing -- all has come back normal.  Event monitors captured my rapid beats and premature beats.  Now I am taking 25mg of Toprol each day, which seems to really help, although I still feel the side effects a bit -- sleepiness, etc.

Two questions:

1.  Does anyone have any idea as to what causes this condition to begin in the first place?  I'm very frustrated by suggestions that it "must be stress" in the absence of an obvious physical cause.  I know myself well, and stress is not the answer, nor is caffiene, alcohol, etc.  Could a virus have triggered this?  If so, is this type of condition generally life long, or time limited?  I somehow feel either hormones or a virus must be the underlying culprit.  My doctors seem more interested in just treating the symptoms and not getting to the cause, and I haven't been able to find any info on origins of inappropriate sinus tachydardia.

2.  My cardiologist advised me to continue to exercise as much as possible.  When beta blockers slow the heart rate, does that bar the aerobic benefits of exercise?

Thank you so much!

29 Responses
238671 tn?1189759432
1. A virus can damage the heart, but this usually show up in an echocardiogram. An EP study performed by a cardiac electrophysiologist can determine whether you really have inappropriate sinus tachycardia and what part of your heart may be causing it. Potentially, it could then be treated with an ablation procedure.
2. People taking beta blockers still get the benefits of exercise, though they may not be able to raise their heart rate to as high a level as when they were not taking the medicine.
Avatar universal
This is to both Diane and Julie --  I, too, have had a rather sudden onset of tachycardia and can pretty much trace it back to starting after a bout with the flu and strep throat.  I feel pretty strongly that there has to be a corrulation somewhere, but all my doctors disagree with me.

I also went through surgical menopause in Feburary 1998 and up until May of this year, was not on ANY type of hormone replacement therapy.  Only after I insisted on hormone testing and my doctor determining that, although my hormone level seemed ok right now, my body WAS in fact, sending out massive signals to try and produce hormones (even though it couldn't because I no longer have either of my ovaries), was I put on Premarin .625 daily.  I have not, as of yet, however, found that this has helped much -- certainly not with the tachycardia and fainting (yes, I have had LOTS of fainting spells along with my tachycardia) - but it has helped a little with the night sweats and mood swings.

My doctor also has me on Prilosec for reflux, but, like you Julie, I do not have any of the symptoms of reflux such as heartburn or excessive gas, etc.  I do know that sometimes when the stomach is irritated, it can give you some of the same symptoms as your heart, but like you - I feel the doctors are just trying to treat the symptoms (or grasping at straws) rather than trying to get at the main cause.

I will say, however, that my current doctor (just a plain old family doctor) IS pursuing the cardiac symptoms and complaints.  I have already had one 30-day event monitor and she wants to have another one done because I continue to have problems and the first one did not give them enough information to be able to determine exactly what the problem is.  She does seem more "in tune" than a lot of the other doctors out there.

Avatar universal
I, too, have inappropriate sinus tachy. I am told it is from something wrong with the sinus node. For some to tell you this is what you have and then blame stress is contradicting. It is an "appropriate" response with stress. It is "inappropriate" when there isn't any apparent reason for it to occur. My cardiologist told me exercise is still very beneficial even with the beta blocker hindering your heart rate. By the way I am 43 and not menopausal.
Avatar universal
Your situation is one which is very similar to mine.  Until this past June, I have enjoyed good health.  I had an early menopause, at about age 41-42, the same as my mother.  I began HRT at that time with premarin and provera.  About 5 years ago, the premarin was changed to estratest (estrogen plus testosterone) to help with a complete lack of libido since menopause.  Then I changed the way I receive my hormones as of June 1.  I began taking daily estratest and 2.5 of the medroxyprogesterone (Provera) with no break at the end of each month.  Within two weeks, I began experiencing slight chest and left arm ache, but ignored them since there is no history in my family of heart problems and the symptoms only lasted about a half-minute.  Over the two weeks, the symptoms gradually increased in frequency and duration until, on the evening of June 13, I had my first rapid heart incident which lasted for about two hours.  I finally told my husband what was happening and he made me promise to call the doctor the next day for an urgent appointment.  I made an appointment for 2:30 p.m. on June 14, but never made it, since I had another attack after lunch at work where I actually felt I was going to pass out and the paramedics were called to transport me to the hospital.  They kept my overnight, taking blood regularly and doing EKG's, also a treadmill test.  But all results indicated that I had not had a heart attack.  The doctors kept suggesting esophageal reflux or hiatal hernia, but I had not had any previous symptoms of such.  I was released the next day, but had to have my husband take me back to emergency (at a hospital closer to home) the following Sunday.  They, too, said I had not had a heart attack and referred me back to my own doctor.  I am now taking Ativan and daily aspirin, and Prevacid (which I don't feel I need and the doctor has said I can stop after the end of this prescription).  I am awaiting my first appointment with a cardiologist in September, unless something drastic happens in the meantime.  My doctor has also suggested that these are stress-induced panic attacks.  But I don't feel I have any stress in my life.  Our kids are happily married and out of the house.  My husband and I are in a happy, healthy 31-year marriage and economically comfortable.  My job is fantastic and I am under no stress there.  This is a mystery to me, and the only connection I can made is hormonal.

After talking to the nurse who prescribes my hormones, I went back to taking them on a cyclical basis:  estratest from days 1-25 and medroxyprogesterone from days 16-25, each month.  Five days after I started the medroxyprogesterone, I had another attack at work, but was able to quiet myself down enough to drive home, and didn't get back to feeling normal until mid-morning the next day.  During my previous years on hormone therapy, I did notice that about 3 days after starting the medroxyprogesterone each month, the hot flashes would come back and I would several times awaken in the middle of the night or in the morning with the feeling that I could not breathe enough air.  I would need to get up and do something to burn off some excess energy, go outside or near a window to get fresh air, and then prop myself up in order to get back to sleep after about a half an hour.

I definitely feel all of this started hormonally, but that I might now be caught in some kind of syndrome where the tachycardia will start by itself.  I have cut out all caffeine (I never had much anyway), drink only water, have started taking magnesium, calcium, potassium, etc.  I am also now afraid to take any hormones ever again, and I'm only 52.  I had hoped to have another 50 years!  

There must be some connection to hormones somewhere.  I just feel it.  I'm sure there are many other women out there who feel the same.
Avatar universal
Hi folks. I am a 39 year old male who has had a history of a-fib over the past 10 years. It occurs only when I have been startled from sleep and my system is thrown out of whack. I had read somewhere that a-fib is caused by a sudden rise or drop in blood pressure and believe this is the cause in my case. As usual I have heard all the excuses from the doctors that it is stress, alcohol, depression, smoking, blah, blah, blah. I was wondering if anyone else has noticed this correlation between being at ease and then experiencing a sudden shock or fright to trigger their a-fib?

Avatar universal
Hi John, IST and a-fib are two different things, as you probably are aware. This post has been marker IST so I'm not sure you'll get much feedback. You could look for a post marked a-fib or when you list your name include some comment about a-fib (in the same box). Hope this helps.
Avatar universal
Thank you to the Heart Forum doctor for your response -- but it really didn't answer my question.  I'm trying to get information as to what causes IST to start in the first place.  Is it a neurological problem or something structurally that changes about the sinus node?

Thanks so much for any info.
Avatar universal
I am a healthy 51 year old woman and I still get my period regularly.  I started having suprtventricular tachycardias about 3 years ago.  I've been through all of the cardiac tests and am told I have a healthy heart with slight mvp with no regurgitation.  I was put on the lowest dose of a beta blocker (sectral) and the lowest dose of a calcium channel blocker (verapamil).  I am told my svt's are not life threatening but they sure do interfere with my quality of life!  I've had two electrophysiology studies and am told my svt's can't be ablated (or I should say it would be dangerous to try) because they are focused on the left side of the heart and in order to get there a hole must be "poked" through the heart from the right side.  

Well, I have just been tested for and seem to come up positive with lyme disease.  I had heard in the past that lyme disease causes heart block only, but this physician that diagnosed me insists that it could cause svt's.  Has anyone heard of this?
Avatar universal
Here is some general information on inappropriate sinus tachycardia.

Sinus tachycardia is defined as a heart rate of greater than 100 beats per minute originating from the sinus node. Sinus tachycardia is classified as either appropriate or inappropriate. There are many causes of appropriate sinus tachycardia such as exercise, anxiety, panic attacks, dehydration, deconditioning, volume loss due to bleeding or other loss of body fluids, hyperthyroidism, electrolyte abnormalities and many other conditions.

Inappropriate sinus tachycardia can only be diagnosed when all causes of appropriate sinus tachycardia have been ruled out. It is not clear what causes inappropriate sinus tachycardia but possible etiologies are an increase in the rate at which the sinus node depolarizes and an increased sensitivity to adrenaline. Once the diagnosis has been made by ruling out all of the potential causes of appropriate sinus tachycardia there are several treatment options. If the symptoms are not overly concerning no treatment needs to be done. There is no increase in morbidity or mortality in persons with this condition and they can expect to have a normal life-span. For persons in whom the symptoms are unbearable medications such as beta blockers or calcium channel blockers can be used, usually with good results. In the rare person unable to tolerate medical treatment catheter ablation (burning) of the sinus node with insertion of a pacemaker or surgical removal of the sinus node have been used in the past. Newer techniques are being developed using catheter ablation to modify and not destroy the sinus node thus avoiding the need for a pacemaker. This procedure is still in it's infancy and should only be undertaken at a major medical center after consultation with an electrophysiologist.

Below are some journal articles that address this topic in depth. Your local medical library should be able to help you find copies.

Review Articles:

Krahn AD. Yee R. Klein GJ. Morillo C. Inappropriate sinus tachycardia: evaluation and therapy. Journal of Cardiovascular Electrophysiology. 6(12):1124-8, 1995 Dec.

Inappropriate sinus tachycardia is an ill-defined clinical syndrome characterized by an increased resting heart rate accompanied by an exaggerated response to exercise or stress. It is not associated with underlying structural heart disease. The mechanism may involve a primary abnormality of the sinus node demonstrating enhanced automaticity or, alternatively, a primary autonomic disturbance with increase sympathetic activity and enhanced sinus node beta-adrenergic sensitivity. The diagnosis of inappropriate sinus tachycardia is one of exclusion. It is most common in young females, with a disproportionate number employed in the health care field. Autonomic and electrophysiologic testing may be required in selected individuals to clarify the mechanism and rule out sinus node reentry or right atrial tachycardia. Therapy of inappropriate sinus tachycardia is empiric. Pharmacologic approaches include beta blockers or verapamil. Radiofrequency catheter ablation of the superior portion of the sinus node shows promise as a useful alternative in patients with refractory symptoms.

Avatar universal
My HR goes into a SVT range as soon as I stand up. Laying down HR can be 100bpm, 170-200bpms as soon as I stand. HR will continue this high until I lay back down again. So physical activity is very tough. I am on lanoxin and pindolol, 120bpm is the lowest HR I can get while standing or doing any activites. Is there anyone else out there that has symptoms when HR gets this high. I feel lightheaded, short of breath, nausea. All tests showo no heart disease. My electrophysiologist has not found any electrical pathway problem so far, I have not had an EP study. Monday I will have a Tilt Table Test.

Avatar universal
I have read somewhere that lyme disease can cause arrhythmias.

Leslie, How does your dr. know if you don't have an extra elec. pathway if you haven't had an ep study? Is he going by an ekg or something?  They found out mine was inappropriate sinus tachy. primarily by the tilt table test, only because it happened during it. When they got the holter results back it was caught then, too. I wasn't aware of my heart beating fast. I experience palps when it occurs now, the palps are very weak because of the atenolol. I had those symptoms you mentioned plus fatigue, dizziness and brain fog, but I don't know if these symptoms were from IST or NCS. The light headedness could be from either. The nausea is from the NCS. My ep said he felt my IST was triggering the NCS. I, also, have mild mvp w/mild mr and mild tr.
Avatar universal

   My doctor seems to think he can look at premature beats before my SVT while on tilt table. I passed out in April, only thing I could remember was going up 4 steps heart rate going up and feeling nausea. I believe the doctor feels my syncope was anixiety. I have not been seen since passing out. The day I passed out my husband called doctors office and talked to another doctor who didnt seem concerned. I didnt get a call from my own doctor after this happened.  I called my doctor after 3 weeks, to see if I could find out about why I passed out and have had waves of passing out since, he said I could have a TTT. I can tell you when HR is high it is not because of, what I eat or drink, or any kind of a mood swing. Just get me in an upright position and HR is high.  I noticed BP going lower and lower while laying down. I called doc and told him I felt lighthheaded, and short of breath while laying down, BP was 75/55 at that time. When I stand BP is 150/100.  I do not like taking beta-blockers, I gainned 100lbs in 10 years. Doctors will say that they dont make you gain weight , I would have to debate them on this. Is NCS like POTS? I have wondered that I could have something liek this.

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