@ted3
It sounds like your device has the exercise mode turned on. That mode will react to movement and raise your pulsing rate up. You mentioned that as goes up just walking.

About a year ago a pace tech wanted to turn my on after hearing how much I exercise. She turned it on after never having it on after almost 20 years . I found like you I did not like the feeling my heart being paced higher from just getting up or walking much less higher exercise. I asked them to turn if off and they agreed.

I do Sprint Triathlons. My heart does respond to the need for more oxygen and blood on it's own. My pluse rate though will not go below 70 as that is the resting pulse it is set at. If I did not have it at 70 it would go into 30s at rest because of medication I take.

Have you ever had a stress test after you had your device implanted? If now would discuss one with your cardiologist. Have them turn off the exercise mode and how you heart does without the exercise mode. Does it respond to exercise on it's own?

My heart (and everyone heart is different) and cardiovascular system on the stress test reacted the way it should during by raising my PR and BP up as my exertion got higher without the exercise mode turned on. I was on a 17 minute test and completed the 17 minutes.

I am a heart failure patient (cardiomyopathy caused not cardiovascular caused) and have had a ICD/Pacemaker since 2006. I do water aerobics 8 times a week, swim a mile twice a week, and ride my bike 20 miles twice a week. I do not need my exercise mode turned on and I do notice my pulse rate go up with exercise but also note that it goes down to my resting pulse rate quickly after exercise to 70 bpm where it is set at.