Caution: Beta Blockers and Atrioventricular Block

 Propranolol is a beta blocker and is the only drug approved by the FDA for the treatment of Essential Tremors. Beta blockers cause the heart to beat more slowly and with less force. Beta blockers can also cause a second-degree Mobitz type 1 (Wenckebach) Atrioventricular Block. Medical terminology like this, can and does sound scary. When it is happening to you it is a very scary experience. If you take beta blockers it may not happen to you, but you should be aware of the possibility of an AV Block.

I’ve been on beta blockers for my hypertension for about 35 years. First I was on 80 mg daily of Propranolol. My PCP changed my prescription to 50 mg daily of Atenolol about 6 or 7 years ago.  During this time my Essential Tremor was fairly masked by these beta blockers. When I needed very steady hands I could always self-medicate with 40mg of Propranolol and get 4 or 5 hours relief.

This all changed last Sunday.  We got up late and I took my daily 50mg of Atenolol during breakfast.  I didn’t feel I was at the ‘top of my game’ and Jill encouraged me to check my blood pressure.  It was fine but my heart rate was much lower than my usual mid 60’s.  Checked my oxygen levels with a pulse oximeter.  Oxygen levels were 97% but again I had a very low pulse rate.

I continued to check my vitals during the afternoon but after a couple of readings with a pulse rate of 35 we decided it was time to seek medical help.  I drove myself to the local Urgent Care which had a hand written sign on the door indicating they were closed.  So I headed to Ann Arbor and the University of Minchigan’s hospital ER facility.

After a couple of minutes of admin discussion and a quick talk with who I guess was a triage person, a tech took my BP and heart rate. This was quiclly followed by an EKG snapshot and blood draw, and a chest x-ray.  All this happened in a matter of 15 minutes.  The nurse who took the EKG snapshot mentioned “a block” to no one in particular.   Let’s pile on my anxiety level. I was having visions of needing a heart stent.

Another nurse settled me into bed and wired up to an EKG monitor.  The steady beep of the sinus rhythm from the monitor wasn’t steady.  I turned so I could view the monitor and I could see that the pulses had gaps in them.  Also the monitor was flashing Afib. Sometime during this period the nurse returned and applied two large defibrillator pads to my chest.  This is getting serious!

Doctor #1 comes in with the first good news. The blood work came back clear. “It’s most likely a Wiki Block”.  After he left Google sorted out that it was Wenckebach.  We discussed my general health.  I think it was this doctor who asked if I had seen a cardiologist and/or had an EKG seeing I was on beta blockers. I had not and was surprised at all medical advice I had received in the past had indicated beta blockers were a ‘safe’ medicine.

The beta blockers were delaying the signal for my heart to beat. The other good news was that I wasn’t suffering from AFib (Atrial fibrillation).  It seems that EKG monitors interpret any irregular heart beat as AFib. We also discussed my self-medication of 40mg of Propranolol for my Essential Tremors. In his opinion this was a very bad idea particularly as I was suffering from an AV block.

Now begins the long wait. I didn’t have any of the common symptoms they expected. No sweating, chills, lightheadedness, nor pins and needles, nor weakness nor cognitive impairment. Somewhere around 8 to 10 hours after I took the Atenolol, my heart beat started to steady. Just to be super sure I wasn’t going to collapse on them, I had another blood draw which came back negative.  After a couple more hours they decided I could go home with a referral to a cardiologist, a 5 day heart monitor ordered, and advice to see my PCP later in the day as it was well past midnight.

Later that  day, my PCP didn’t prescribe an alternative to the Atenolol.  “Just monitor the BP and contact me if it starts to move over 90 diastolic. It is difficult to adjust to a resting heart rate 85+ but so far the BP is holding steady.  

The 5x24 heart monitor arrived.  No drama there.  The adhesive irritated my skin. The summary results were posted to myuofmhealth.org but will have to wait until I see the cardiologists for interpretation. That appointment is a couple of weeks from now.

Beta blockers which I always considered a ‘safe’ drug are not always safe. If you take beta blockers for your Essential Tremor, you should monitor and record your heart rate and blood pressure on a regular basis.  Stay safe and healthy.

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