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

[Julie]

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!

Julie

[Barb]

I am a 45y/o female with IST.  I also have a congenital heart defect, mild pulmonic stenosis. Apparently, 3 of my valves now show some regurgitation per echo,with the pulmonic valve showing the most, but not enough to require surgery.  In fact my EP Cardio calls my valve status "red herring".  The diagnostic process was long, drawn out and filled with dissention among at least 5 cardiologists.  The process was filled with stress for both me and my family.  This made it difficult to know how to respond when a dr. would ask about stress. I had 2 event moniters, 4 separate holter moniters {on various levels of beta blockers], 2 heart caths, 3 EP studies and 2 sleep studies. Always the same results were found-continual IST and some other minor arthymias. Noone could decide on what was the most approprate tx. I took lanoxin, high doses of beta blockers, and diazide for 5 years.  The interventions would work initialy, but the IST always returned. I grew weaker, profoundly fatigued and was unable to take good care of my kids or perform my job duties well.  I was in cardiac rehab for 5 years also, which seemed to be of some help.  The good news is that in the past yr. I have had 2 sinus node modifications that have been very helpful. I felt dramatically better after the first one but the IST gradually returned. The atrial fib that dr. L ablated at the end of the procedure however stayed away.  The second SNM however seems to be working per cardic stress test. I no longer take any beta blockers. These were hard for me to tolerate because I have normally very low blood pressure to begin with.  I hope that someday drs. will be able to dx this more easily. I could go on forever about how difficult this was for me and my family. I am thanful my cardiologist never stopped looking for answers.  I will be forever grateful for Dr. L's knowledge skill and courage.  I hope this story helps someone.

[Connie DeMarco]

I wasa fine untill I had a back injury in 1979 when I had to sart having myleograms and other test for my back I had to fight the workmen's compensation insurance company at every turn. Finally after 6 mo. of severe pain I was rushed to the hospital with heart rate of 290 min. I was give digitalis and had allergic reaction, then the dr's started different heart meds. I was like that for 16 hrs. not expected to live. Finally the cardioligist gave me pain medicine for my back and valium for my nerves.Heart rate went down to 160 and then the heart medicine corogard took over and the attack broke back to 82 min. I took the corgard for 6 month then started tohave severe chest pain and was hospitalized again. I was havin main artery to the heart spasms which cut of the blood supply. The dr. put me on procardia with the corgard. Man, did i feel bad with the meds. In 1980 I had back surgery which took care of the pain.  Found out later the corgard was causing spasms and procardia was making me feel bad.  I had a hear cath. and the new Dr. took me off of all meds.  Said tachycardia I had was caused by stress and pain.  I was fine untill 1999 when I was again injured and in a lot of pain and stress. Tachyardia again. Dr put me on zannax after a stress test was normal .  Haven't had an attack since.  There is a fairly new procedure that the dr's can go in non-surgically andpin-fire the little wire looking thing that makes the heart beat. This causes scarring at that point.  You are never bothered with tachyadia  agian.  I am considering this because a lot od doctors do not like giving valium or zannax and they say it's not stress or pain but I don't really know what to do.  Stay on the pills are have the procedure which does have risks. anyone that has had this procedure please write me. Sincerely and love to all u out there.     Connie

[miranda]

Hi,

My eight year old son has been diagonised as having Sinus Ventricular Tachycardia. I live in Sydney (Aust) and am looking for more details regarding this condition. Nicholas first had an SVT episode at 12 months of age and his heart rate on ECG was monitored at 320 bpm. He was injected with Digoxin and was on this for over 6 months. Since then he has seemed to be fine until 4 days ago when he had a fever. A visit to our GP saw him in the Emergency Dept with a heart rate of 245 bpm. He was injected with another drug which brought his rate to 80-90 bpm.
Two days later he was again in ER with 195 bpm. He is currently on medication to slow his heart rate (Sotalol Hydrochloride 40mg)
and this seems to have an effect on him. I will be seeing a cardiologist in 2 weeks but at pesent am trying to find out as much as I can re this condition. Any information will be very much appreciated. Thanks.

[to Carol from Sue RN]

Andrea, Just read your post. How long have you been on BC pills? If it is recent, you may want to try a time off them to see if your heart rate improves (if you can change to another BC method). I do think there is some link to hormones and increased heart rate. Otherwise from what I've been reading here and in talking to my cardiologist, no one really know what starts IST. I'm still working on trying to find the right mix of meds to treat IST and my hypertension. It is taking a while. Don't give up hope. And DON'T let the doctor tell you it is from "stress." or anxiety. Take care - Sue

[Barb]

I am 45 f in an allied med profession. I have had 2 radiofrequency modifications of my atrio-sinus node in the past year, as well as an ablation of an atrial flutter. PRIOR TO THESE PROCEDURES, my life consisted of mind-numbing, bone deep fatigue, nausea, SOB, and SVT 24/7. Since I was born with pulmonary stenosis I was already followed yearly by a cardiologist. After 5 yrs of cariac rehab, lanoxin and ever higher doses of beta- blockers Iwas dx with IST after EP studies.  The meds and rehab always helped initially, but after a few months the symptoms would return. I lost 40 lbs. Even when I was Sleeping [per sleep studies] my heart rate was 115bpm and up.  The diagnostic process was excruciating and took 7 yrs. My children suffered, my marriage suffered and my career suffered. I am eternally grateful to my cardiologist and the 2 EP CARDIOLOGISTS  who were finally able to find effective treatments.  The EP doc who did the rf modifications has quietly developed a way to map the sinus node and phrenic nerve to avoid complications. He has done ~40 with no major complications.  I only wish the dx process could be made easier and shorter for others with this problem.  My life has been drastically altered by the YEARS of fatigue etc and uncertainty. I have a few suggestions gained from my experiences. Is research continuing?What can be done to keep this from happening to everyone with debilitating IST?

[jan]

Hi Sue, Some have referred to the all the initials as cardiac alphabet soup. Usually you can go under the search option and find out what they mean and what they are all about. NCS is neurocardiogenic syncope, POTS is postural orthostatic tachycardia syndrome. You can see why initials are used. :o)  Hope this helps.