Heart Rate Variability While Exercising

I am a 50 y/o female that has been c/o fatigue; been more extreme since recent bout with viral gastroenteritis. I experienced some SOB and significant edema. Seen by a physician who ran some labwork which came back within normal limits, BNP was 253, she did give me lasix for a couple days for which I dropped 14.5 pounds in 2 days. She also ordered a cardiac echo and stress test for me.  Echo showed some regurgitation in the mitral and tricuspid valve but nothing to warrant further treatment and left atrium dilation, and I believe left ventricular end diastolic pressure elevation...again, told nothing to be concerned with.  I've had episodes in the past where my heart rate has dropped down to the upper 30's and then would come back up to 50-60 range.  I would say my normal resting HR has always been around 80.  So, since they labwork was good, the cardiac tests were fine, my PMD said my fatigue has to be my depression.  I personally don't think so but hey, I'll go with it for now.  I'm faithfully going to the gym and working out for 1-2 hours 4 days (or more) a week.  I work hard while I am there, riding bike for an hour, getting my HR from 130-150+.  During that hour though I will see my HR drop down to 60's and then down to the 40's.  It will stay there for maybe 3-5 minutes and slowly climb to 70 and then wham, I'm back up to the 130's again.  To me this does not seem normal.   I'm thinking this may be the reason for my fatigue with the HR fluctuating as it does and not my depression. They have resorted to giving me ritalin to take daily now just so I can function; I hate taking it but if I don't, I certainly wouldn't get anything done.    Am I off in thinking that 45 minutes into biking hard and my HR is running in the 40's?  I know nothing showed up in the 10 minutes of walking on the treadmill but I can't believe that captured the entire situation.  I am on no medications to cause lowering of the heart rate.  I do take lisinopril for my blood pressure but no beta blockers or others that would contribute to this.  I would be interested in hearing your thoughts on this.  Would you think a holter monitor be an appropriate thing?  If so, how do you get your PMD to do this when they are set on it being depression because nothing shows up in the labwork & the cardiac tests?   I do have hypothyroidism and idiopathic intracranial hypertension, type II diabetes (last A1c 5.9).

[Dr Vinod]

Hello!

1) Some of the side effects of Ritalin include:

Nervousness and insomnia are the most common adverse reactions but are usually controlled by reducing dosage and omitting the drug in the afternoon or evening. Other reactions include hypersensitivity (including skin rash, urticaria, fever, arthralgia); anorexia; nausea; dizziness; palpitations; headache; dyskinesia; drowsiness; blood pressure and pulse changes, both up and down; tachycardia; angina; cardiac arrhythmia; abdominal pain; weight loss during prolonged therapy.

So discuss these with your Physician as we think this might be the reason for your drop in Heart rate.

2) Lisinopril also causes irregular heartbeats:  tired feeling, muscle weakness, pounding or uneven heartbeats and in some individual’s chest pain.

So discuss if they can change to some other alternative medications and also to calculate the dosage to see if these two drugs are in therapeutic range and if you have to continue what all precautions you should take.

Take care and come back to us with further queries!