Background:

We have a black indoor cat (probably American Shorthair) adopted from
a shelter 6 years ago at the approximate age of 5 years old. From
early on he had trouble coughing but it was not hairball; this was
eventually considered asthma and he had excellent results for a few
years with injections of a steroid every 2 to 4 months (the 4 month
periods after we removed most of the carpeting in our house). At age
10 he had a "geriatric profile" done that showed high thyroid but not
high enough for any action to be taken (free T4 test is done every few
months). The vet also found a heart murmur.

After the 1st of 2 heart ultrasounds, the cat started taking 12.5 mg
of atenolol (spelling?) daily to help with cardiomyopathy. His murmur
seemed to improve according to the vet for months but the 2nd
ultrasound recently showed a worsening of the situation. The cat is
scared easily. especially at the vet's, and his heartbeat is often
fast and we are trying to check it at home using someone's borrowed
stethoscope.

Problem we need help with:

Yesterday the cat was walking and then fell on his side and starting
meowing loudly (the sound he sometimes makes when in another room and
looking for us!). My husband panicked and his loud voice and rapid
motions further scared the cat who ran to hide under the bed. After a
while we got him out and he was calm and able to walk and he took some
treats. Today, just under 24 hours later the same thing happened but
he did not run as we acted calmer. He was able to walk normally again
(immediately) and took treats and some tuna juice left over in a can
and has been cleaning himself and now is sleeping on a chair.

One possibility is that blood clots are paralyzing his leg(s)
temporarily at this time but the fall doesn't yet last more than a few
seconds. Are there any other things we should ask the vet about? I'm
calling in the morning for an emergency appointment.

Thank you for any reasonable suggestions.