I have a concern so I'm going to ask my question here on
sci.med.cardiology.
I've already talked to my pacemaker center and asked my
cardiologist for her opinion.

What is currently happening might be due to the pacemaker
but I think it is my own equipment that isn't quite right.
It's going to take me a few lines to explain....

Similar things are happening since the pacemaker as
before I had the pacemaker installed.    ie.   When walking my pulse
goes up but then, at some point, it drops down.
Before the pacemaker I had extreme bradycardia.  My pulse
could have easily been in the 40s.   While sitting the pulse
could be in the 60s but if I walked up stairs or moved too
briskly my pulse would drop down to thirty.
With  the pacemaker when my pulse goes quite a bit higher then it drops
down to 60. So.. the same thing but much less extreme.

More background:   I went into the pacemaker center
my first checkup.  I told them about my heart rate
dropping and they said that the pacemaker was set
to a 130 bpm limit.  They said above 130 the pacemaker would
put me into 2-to-1 heart block.  (Above 188 bpm the ICD
would defib me but that is an entirely different thing)
So... to allow me to be more active they raised my
limit to 150.

Symptoms since that change:  Since the pacemaker
appointment I have still noticed my pulse dropping down.
(1) I went for a walk yesterday. I was walking and
feeling fine but when I started to go up a hill I noticed
a change and had to stop.  Upon stopping my rate
was in the 60s.
(2) I was cleaning up the dishes after dinner
(so only moderately active) and then went upstairs
(no particular hurry) and then I had a slow down.
pulse in the 60s.
It seems odd that my pulse would go shooting all the
way up to 150 from such modest amounts of work and
so.....
(3)  Today I tried walking again to test things out.
This time I wanted to see how high my pulse actually
got before it dropped down.  To the best of my ability
using a pulse-reading watch  I saw my heart rate
go up to maybe 120s before it dropped down to 60s.
So don't *think* I pushed my heart rate to 150
but it still dropped down anyway.  I suspect it is
my own sinus node that is messing up and not
the ICD.  Of course I don't know.

I'm all for gradually improving my aerobic conditioning
and I'm pretty sure that I'll be much better off if
I do.  But in the meantime, here is my question:
Would there be any point in testing to see whether
(1) I'm actually hitting the pacemaker's 150 limit or
(2) it is my own sinus node is screwing up or
(3) there is something else wonky going on?

Anyone here on sci.med.cardiology have any ideas?