Hi, Moortje. Too much Mestinon/acetylcholine can cause bradycardia, heartbeat below 60.

Has anyone checked your O2 when your pulse goes up?

When MG gets worse, your O2 can go lower, usually due to weak chest wall muscles. Are you more short of breath when your pulse goes up? Or in between Mestinon doses?

When the O2 goes lower, the body tries to compensate for that. The heart beats faster to circulate more oxygen to your tissues.

A higher heart rate can mean other things, too, though. It can go up if you're dehydrated or have other medical conditions. It might go up if you've had too much salt.

You should probably bring it up to your internist and/or neuro, because any changes or trends in MG or your overall health is worth doing that!

Annie