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Drugs that lower your heart rate(11 posts)

Drugs that lower your heart rateCRM
Apr 25, 2002 6:31 AM
About a week ago, I posted about the sudden drop in my fitness. I received several suggestions as to the cause, including mono. I saw a doctor and it turns out that my thyroid is hyperactive. The result is that my thyroid is producing too much adrenaline and it's screwing up the way my cells convert oxygen into energy (lay description).

Anyway, I can't get in to see an endocrinologist for over a month to take care of the thing. In the meantime, my doctor prescribed beta blockers, drugs normally given to heart patients and designed to lower your heart rate.

I started them yesterday and went for a short ride last night. They definitely kept my heart rate down on the ride. I topped out at 89% of maximum even on the hardest hills which normally would have had my heart rate well into the 90%+ range. Most of the time, it was well below that. Unfortunately, this was not necessarily a good thing. My legs, shoulders and back hurt much more than usual. My theory is that my heart is not pumping enough blood (and therefore oxygen) to them.

My question is: Has anyone else dealt with beta blockers or a hyperthyroid condition? Are there any do's or don'ts? My doctor didn't seem to know the answers to these questions as they relate to cycling. Thanks so much for your input.

P.S. - This is really frustrating. I worked hard over the winter for one reason: to be in good cycling shape right now. All that work - for nothing!
Ahhh, the creeping of the years...cory
Apr 25, 2002 7:41 AM
I went through the same thing about 10 years ago. I was running 70-100 miles a week, in the best shape of my life in my early 40s, and suddenly slowed down about 1:30 per mile. Turned out to be a heart arrythmia, probably genetic--a different problem than yours, but with the same psychological effects, I imagine.
First thing to do is don't borrow trouble. Don't sweat it much or assume anything until you see the doctor--they have a good handle on a lot of thyroid problems, and you may be back up to full speed within a few days or weeks. For now, just do what you can and wait to see what happens, meanwhile thinking evil thoughts about the politics that makes it impossible for you to see a doctor when you need one.
In the worst case, your performance may be permanently reduced. Mine is--the arrythmia isn't dangerous, but it's apparently going to be permanent.
Sounds awful, but...what can you do? I wasn't THAT good a runner anyway, just an enthusiastic one. My knees were starting to hurt anyway after 20 years of pounding, so I started cycling instead. I had no personal records to feel bad about, and I improved on the bike right away, because I'd been only a casual rider before. Last year, in my mid-50s, I trained hard and went farther and faster than I did at 42. Day after tomorrow I'm going to ride a hilly century. It'll probably take me six or seven hours, but it's way better than being dead.
But don't assume anything until you talk to the endocrinologist, because he may have a magic wand.
I'm not a doctor butgrandemamou
Apr 25, 2002 8:28 AM
my wife did suffer from a hyperactive thyroid. She had similar symptoms, lack of energy and just generally feeling awful. Her treatment included radiation to kill off her thyroid. The downside is she has to take synthetic hormones the rest of her life the upside is that as long as her meds are straight she functions perfectly normal.

I think getting expert help (endo guy) is the right move. Be upfront about your desired level of activity and get all the answers first. Once your thyroid is dead they can't bring it back. Do a google search it's not as uncommon as you may think.

I don't want to alarm you. My wife leads a normal life. As a matter of fact she gave birth to a healthy baby boy one month ago.
re: Drugs that lower your heart ratemja
Apr 25, 2002 9:40 AM
On the action of the beta blockers, don't worry about the lower heart rate, consider that the "contractility", or the force of the pumping action, is likely greater along with slower pulse. A search on the web for the full FDA info on your particular medication -- info that your doctor or pharmacist should also be able to provide -- would enlighten you about its effects.

As long as your thyroid condition is untreated, your going to be messed up -- i.e., just not feeling right. You might even want to lessen your physical exertions for a time.
re: Drugs that lower your heart rateJS Haiku Shop
Apr 25, 2002 9:41 AM
i'm also using beta blockers, a low dose, daily. however, i'd think it more likely that your mind is pretty active in the differences you realized yesterday. i'm not so sure that one day of taking the med would have that kind of direct affect. the docs indicated to me that it would be 3 days to 3 weeks before they became effective for me.

btw, mine are for migraines. combined with some other drugs, and a vitamin/herbal daily dose (legal, of course), my headaches have gone from two or more per month to few-and-far-between. and no problems from the beta blockers. in fact, i'm stronger now than before i started taking them.
re: Drugs that lower your heart rateMasterTi
Apr 25, 2002 10:34 AM
Hyperthyroidism is a common condition that affects people young and old, females and males. It occurs when the thyoid gland produces too much thyroid hormones for whatever reason, hormones that normally regulate the body's metabolism. Too much hormone results in too quick metabolism, and everything speeds up, including heart rate and weight reduction (about the only bonus in this condition).

Beta blockers block many of these symptoms of thyroid hormone excess, such as the fast heart rate, tremor, and sweats. However the cardiac effects that you describe are not easy to avoid. They blunt the heart rate, including its response to exercise, and blunt the heart's contractility (its strength of contraction). As a result, you are indeed correct, the cardiac output in response to exercise is reduced, and less output from the heart does indeed translate to less blood flow to muscles during exercise. It's no surprise that you can't go as hard or as fast - the medication is doing what it's supposed to do.

My wife had this condition years back, and was on betablockers over the winter. She felt like a slug when cross country skiing and could not go her usual speed no matter how hard she tried. As long as you're on the betablockers, this will likely limit your ability to exercise aerobicly. Great for steadying your hands if your form of exercise involves target practice though.

My wife got rid of the betablockers when she got the definitive treatment from the Endocrinologist (radioactive iodine), and now takes thyoid hormone replacement instead as her thyoid gland got nuked by the iodine. It's one pill per day, with no side effects, as it's just replacing what was previously made by her own thyroid gland. Other than having to remember to take this pill daily, she leads a completely normal life. We would highly recommmend talking to your Endocrinologist about this option! Other things to consider in this decision include age, gender and child-bearing status. My wife could not get pregnant during the radioactive iodine treatment, but has since given birth to our 3 children with no problems whatsoever.

Good luck with dealing with this illness!
Regarding your wifeCRM
Apr 25, 2002 11:03 AM
Now that she is taking the supplement, is she able to exercise at the level she was at prior to her thyroid problems?

I can handle taking a pill every day for the rest of my life. It's probably just the first of many to come. I just hope that I can function normally on the bike again.

Thanks again for your excellent information and insight.
Regarding your wifeMasterTi
Apr 25, 2002 1:23 PM
IIRC, my wife was on the betablockers for about one year before she got the radioactive iodine, and during that year, skiing and cycling were sluggish to say the least.

One year is a typical trial of medical therapy, as there is a chance that the thyroid gland will behave normally after medical therapy alone for one year, and therefore eliminate the need for the radioactive iodine. The term "radioactive" obviously scared my wife at that time as we had not had our children yet, and she wanted to avoid the radioactivity if she could, even though it was explained to us that it was a trivial dose that would not cause any harm for future pregnancies. Unfortunately however after the medications were stopped, the thyroid was overactive again, and this time the Endocrinologist strongly advised the radioactive iodine as a definitive treatment.

The radioactive iodine took several months to work (IIRC about 3 months), after which time the thyroid gland was now rendered underactive. She was then started on thyroid replacement pills, but it took another few months to figure out the right dose. Unfortunately the right dose is not calculated by some magical formulae - it was trial and error with measurements of blood levels of the hormones.

She's now completely back to normal, and rides the bike and skiis as well as she ever did, and with no hinderance whatsoever. The only difference is that she needs to take one pill per day, and needs a blood test once or twice per year to make sure she's still on the right dose. My wife never raced a bike, but I'm sure if she did, she would not have been able to do so and be competitive during the year and a half or so that she was treated for hyperthyoidism. She still felt tired for months after the radioactive iodine, but this time due to the underactive thyroid, rather than the betablockers.

The other option would have been to get the radioactive iodine earlier, so as to "get it over with", and not waste the time on the betablockers. It depends on ones' aversion to radioactive iodine. Tough call, and a personal decision that you will need to discuss with your Endocrinologist.

Good luck!
Thanks so much for all the info (nm)CRM
Apr 25, 2002 11:00 AM
re: Drugs that lower your heart rateKary
Apr 25, 2002 1:03 PM
Last year I was put on beta blockers for hypertension. On my first mountain bike ride I could not climb the first hill I hit. My normal resting pulse is 44 it was below 30 on the beta blockers. Went straight to my doctor and spoke to him. I am now on a different medication and have no problems.
Talk to your doctor. Let him know your activity level and I am sure they will find the right treatment.
re: Drugs that lower your heart rategebbyfish
Apr 25, 2002 6:11 PM
You might want to ask your doctor about PTU, or propylthiouracil. This medicine will block conversion of thyroid hormone to its more active form without causing the bradycardia. It should buy you time until you can see the endocrinologist. If your doc doesn't feel comfortable with this, you might want to ask him to call the endocrinologist's office for advice on it. Since they can't get you in for awhile, they should at least help him out with advice. The last thing any self respecting doc would want to cause is one of his patients not to exercise and he ought to help you on to a different medicine, more agreeable to your body. Hope this helps. Paul