Rate response problems with Medtronic Azure pacemaker while cycling
I am a 69 year-old experienced male cyclist, having ridden for over 35 years. I began cycling after experiencing a hip injury that still prevents me from running. I always ride with a chest-strap heart rate monitor. Around 12 months ago I began experiencing fatigue, dizziness and low heart rate while riding, occasionally at first and then with increasing frequency. I was eventually diagnosed with sick sinus syndrome/bradycardia, and had a Medtronic Azure dual-lead pacemaker implanted a little over six months ago. It's my understanding that the Medtronic Azure uses a single rate-response sensor based on accelerometer technology.
Soon after I started riding again after implant surgery I noticed problems with rate response, particularly on long, slow climbs requiring a lot of effort, but where apparently there wasn’t enough upper body movement to trigger the accelerometer to increase my heart rate. Over the course of several months I made several trips back to my surgeon to discuss these problems, and the sensitivity level of the pacemaker rate response was adjusted upward each time. After each adjustment my rate response seemed to improve for awhile, but I eventually encountered episodes of low heart rate in situations such as climbing.
At this point the sensitivity of the rate response sensor is at its highest setting, and I am still occasionally experiencing situations while riding where my heart rate is too low to support my level of effort. I’ve discussed the problem with Medtronic, and they acknowledged that rate response during cycling is particularly problematic for their accelerometer-based rate response sensor technology. I’m beginning to think that the Medtronic pacemaker with its single-sensor accelerometer technology is not appropriate for cycling activities. I plan to see my surgeon again to discuss these issues, but I want to do my homework first so that we can have an informed and useful discussion.
My question is this: are there pacemakers out there that use rate response sensor technology more appropriate to cycling?