SVT or not

[heybob]

I am 30 years old, I started having syncope 5 months ago, my question is...I have been diagnosed with probably having SVT's...the electrophysiologist told me he thinks its AV node re-entry, atrial, or inappropriate sinus tachycardia...but he won't know until the EP study is done.

But I am confused because from everything i've read people with ordinary SVT's are not symptomatic unless they have tachycardia, and I am.  I feel generally ill with malaise and fatigue almost all the time, lost my exercise tolerance (ex weight lifter)... I have had a severe headache disorder for 3 years,  

One recent episode in particular was very disturbing, for about an hour I felt severe lightheadedness, weakness, temulousness, nausea and a sense of doom.  During this time my vitals were absolutely normal  115/70 pulse 85 glucose 88.  After an hour of this feeling very ill, my pulse started shooting up to 140, then 150, then back down to 110 for a while, then hovering at 130 for a while before it died off, during the tachycardia I was very hypertensive with readings such as 195/105 and I felt extremely hot with flushing in the face and the feeling that the air temperature was 90 degrees I had an intense urge to get in a cold shower but couldn't stand up because of lightheadedness, then as the tachycardia died off my mouth became so dry I couldn't talk without being tongue tied.
then I was left feeling beat up from the inside out and traumatized well into the next day.

So my confusion is due to the fact I am so symptomatic even without tachycardia? Might I have some other type of disease which is causing the illusion of SVT's but there is more underlying cause, if so what can it be?  I've had a brain MRI, echo, standard labs, CTX and of course many EKG's.

[Cleveland Clinic]

I bet you will end up being diagnosed with IST.  there is an autoimmune component to this condition which may explain some of your symptoms.  As I said to the other member of the forum, most of these resolve spontaneously in up to 6 months.  It seems to me that at this point your workup is complete and that you should have the EP study.  I am not familiar with any other conditions that could cause this.  Sorry.

[heybob]

Not to mention a bunch of other labs...PT was 14.7, INR PTT normal, D drimer 110.  ABG PH was 7.46 and  o2hb% was 96.8.      During one of my episodes, I had an o2 desat.  to 85 briefly...I'm sure that's happened before when I wasn't wearing  a pulse ox...Those sudden dizzy eppisodes happen to me all the time 3 times per week, I'm sure my o2 drops each time with bursts of tachycardia.  

[heybob]

Doc, Yes I had CBC-D, CMP, TSH and T4, sed rate, liver and pancreatic enzymes...even RPR and HIV.    I have not been tested for pheo.  Given that it's rare, I assume it'll be negative, So, where would you go with this is I'm negative for Pheo?   Is there anything else at all this could be?   I mean, anything?   Could it be a transient electrolyte imbalance of some sort?

Thanks 1 million times over for your time

[Cleveland Clinic]

Hypoglycemia can also cause these symptoms, but this is also very rare.  I am sure your doctor checked your random blood glucose.  Patients who have this condition report these symptoms after their meals.  

[Cleveland Clinic]

I just answered a very similar question for one of the other members of the forum.  The fact that you are having symptoms without any arrhythmia is suspicious for inappropriate sinus tachycardia.  Thyroid disease should be ruled out with a simple test.  There are a few very rare conditions that can cause elevation of catecholamines leading to those symptoms.  The name of this rare condition is pheochromocytoma and it is generally tested for using urine testing for byproducts of catecholamine metabolism (VMA's).