On and off tachycardia -what could cause this? please help

[oliviamarie12345]

My doctor put me on a 24 hour heart monitor because I have been feeling palpitations. The results showed that I go from a normal heart rate one hour to tachycardia up to 140 beats per minute the next hour and back again. There is no arrythmia but it just goes from fast to normal about 10 times a day the heart monitor showed. What could cause this? He has ruled out mitral valve prolapse through a 3-D ultrasound of the heart I had last year, and he has also ruled out thyroid hormones and sleep apnea because when I am sleeping the heart monitor showed my heart rate was normal. Please help, what can cause tachycardia other than mitral valve prolapse, sleep apnea and thyroid issues. P.S. I did have half my thyroid removed in april, but my thyroid tests are normal.

[Jerry_NJ]

There are lots of "brands" o beta blockers, I take a generic Metoprolol, which is the least expensive.  I think some of the brand names:  Toprol for example is considerably more money.  Oh, my BB is also a slow release so that one can take it once a day and still have an effective level of medication in the body around the clock.  I split mine into two doses, one morning and one night because I think that gives me a more level medication level.

[Jerry_NJ]

I'd not consider "hard to take a deep breath" a case of shortness of breath.  So I see nothing in that to suggest a struggle to get more oxygen into the blood stream...i.e. heart/lung efficiency.

Beta blocker do have some side unwanted side effects, but I think most people don't have much trouble.   I am at 100 mg twice a day and it took some time for me to adjust, i.e., my lower HR was accompanied by a very low blood pressure and some dizziness.  That seems to have passed and my blood pressure is low normal.

[oliviamarie12345]

sorry, one more thing

sometimes I do feel it is hard to take a deep breath, like my breathing is shallow

[oliviamarie12345]

yes my normal is for sure 70+, it is usually almost 100. My primary said he would put me on a beta blocker if I wanted, so I think I am going to try that.

thank you for you help

[Jerry_NJ]

You didn't give us a normal resting HR for you.  If it is on the high side of normal, say 70+ then a beta blocker seems like something that could be tried.

Are you aware that your HR has increased? A rate of 140 isn't particularly high, and does not do any harm if there only temporarily.  For example, you may have a HR around 140 when walking fast, and/or uphill.  It would in those situation likely be accompanied with faster breathing.    Do you ever feel shortness of breat?  

Did you think real hard about the time the monitor showed your rate up at the 140 level?  Were you active at or near those times? Were you excited or somehow upset by something at the time the rate when up?   Any or all of these could cause temporary increases in your HR.

Again, a HR of 140 in not normal for a rest state, but it is at the lower end of tachycardia, so don't get over concerned about tachycardia, I think.  I've had period in the range of 130 and didn't even know it.  I am on a high dose of beta blocker to keep my AFib driven high HR from going over 90 at rest.