IST or POTS

Hi I have posted previously, thank you for your time. I am 26 and overweight I just stopped smoking. I went to clevland  heart clinic I have what they said from the echo is mild regergitation in my tricuspid and pulmonary valves. I also have rapid heart rate when standing. I had a heart holtier done which was find my average beat was 77 and went to 136 at night (which was explainable) but my doc here in VA put me on a BB toprol xl which I took for 3 days and then stopped due to side effects and then about a week later had an episode of SVT first time I have ever had that and had to be put on atenolol......I never had the constant high heart rate until the beta blockers now it wont come down and goes up through the BB.....sitting it can go as high as 100 when I stand it goes as high as 140 and comes back down but usually stays around 120-130 when walking around. I also had a very small drop in blood pressure when standing 6 points I think.The doc in clevland said either POTS or IST here are my questions.


Could the beta blockers or the SVT somehow have caused my heart rate to go up and not come down?

What is the difference between IST and POTS how do they tell which one you have?

what tests should I ask for?

thank you

[Cleveland Clinic]

1.  The beta blocker, if anything, should lower your heart rate.  The SVT is probably what is driving your heart rate to be so high.

2.  IST is a condition where the sinus node, aka the natural pacemaker, beats at a higher rate and the rate is out of proportion to the metabolic demand.  Meaning, that one would only expect that high of a rate if the patient were exercising or under stress, etc.  We don't fully understand this condition, but it may be mediated by multiple causes.  Some of us believe that it starts with a viral infection that leads to a derangemetn in the sympathetic system leading to abnormally high catecholamine levels and tachycardia.  Others think that the high catecholamine levels are somehow driven by the brain.  Others yet, think that it may acutally be the natural pacemaker itself that becomes more sensitive to catecholamines leading to higher heart rates.  The condition is typically associated with palpitations, shortness of breath, etc.  POTS is a cousin of this condition, but the patient experiences elevated heart rates when they stand up and they often pass out or feel lightheaded upon assuming an upright position.  In their case, it is the venous tone, which is responsible for returning blood back to the heart, that is somehow defective.  It may also have to do with abnormal catecholamine state or abnormal sensitivity to catecholamines.  The effect is similar in that patients have elevated heart rates.  

3.  A holter monitor and a tilt table test would be useful in differentiating the two.  Sometimes it becomes difficult to tease those two out.  

[jaksmom03]

forgot to add :  I do not get dizzy when standing or lightheaded and was not tierd until the atenolol. I had a baby in NOV 06' and had a uterine infection afterward. I have been under a GREAT DEAL of stress since December. I overheat very easily, I dont suffer night sweats.  I dont feel blood pooling to my feet. thank you

[jaksmom03]

Will getting the weight off help lower my heart rate some?

[Cleveland Clinic]

Getting the weight off might help lower the heart rate.  Have you had an echocardiogram to check your heart function yet?  Just make sure that it is normal.  Sometime women develop heart problems after their pregnancies.  From what you describe about your symptoms.  You are more likely to have IST than POTS.  

[bosoxfan]

There is a new diagnostic test available (at the Cleveland Clinic coincidently) that determines exactly how much blood is circulating in your system.  The sypmtoms you stated could be consistant with hypovolemia (too little blood/plasma) and anemia (too few red blood cells).  This blood volume test can help diagnose the true nature of POTS, syncope and to treat heart failure patients.  There are some very illuminating clinical studies at www.daxor.com (the mfgr of the device) that you should read yourself.  One of the studies done recently is from Dr. Fouad-Tarazi at the Cleveland Clinic that is the largest of it's kind.  Go inform yourself on this as quickly as you can!

[jaksmom03]

THANK YOU SO MUCH.....I am constantly looking but never found this.....Im so glad there are people on here that want to help I have posted other things and got alot of negative responses so thank you for trying to spread information!!!!  I will post this info for other people aswell on other websites.....thank you!!!