IST and subconscious stress?

[NikNak17]

I'm 18 years old and was rushed to the emergency room a couple months ago because of a racing heart rate that got up to 192 beats/minute. The hospital diagnosed me with Superventricular Tachycardia and now I'm on 25mg of Lopressor twice a day. However, the cardiologists I visited told me I have Inappropriate Sinus Tachycardia caused by stress. Is it possible they are missing something because I feel like I'm not overly stressed enough for my heart to beat 200 times per minute for no apparent reason. Does anyone else have IST caused by stress? I feel like the doctors can't find anything physically wrong so they are blaming stress.
-Nikki

[BEACHBUMCAG]

Inappropriate Sinus Tachycardia (IST)

What is IST?
Inappropriate sinus tachycardia (IST) is a condition in which an individual’s resting heart rate is abnormally high (greater than 100 beats per minute), their heart rate increases rapidly with minimal exertion, and their rapid heart rate is accompanied by symptoms of palpitations, fatigue, and exercise intolerance. IST is not associated with an abnormal electrical pattern on the ECG. The heart rhythm in IST appears to arise from within the sinus node, the cardiac structure that generates the normal heart rhythm. (Click here for a quick and easy review of the normal heart rhythm.)  

http://heartdisease.about.com/cs/arrhythmias/a/IST.htm

[anacyde]

So do you have SVT or IST?  Or both?

And yes, any stress can trigger both of those conditions.

[CollegeGirl143]

well thats often how it goes.. if there is no physical reason for your problem, common sense tells us it must be something, and usually that something is stress..

If your heart rate was 192bpm, and it was a normal sinus rhythm, then you would have sinus tachycardia.. your doctor might have diagnosed ist, because that is an unusually high heart rate for normal activity.. in a structurally sound heart, in a normal person,a high rate sinus rhythm beat is usually caused by one of four things.. exercise, infection,dehydration and stress... Now who told you that you had SVT? Often, there are misdiagnosis in abulances or hospitals when it comes to reading ECG's...Despite a normal rhythm, on an ECG, any heart rate over 175 (some models do it at 165) automatically label it SVT, based solely on the speed of the heart rate, and thats not a very good diagnostic tool at all.. Did a cardiologist at the hospital look over your ecg?.

My advice would be to go see your primary doctor, get a referal to a cardiologist and ask for a holter monitor and an echo.