Higher RR interval variations during cycling after AVR

[Robbyha]

Since i was told that i'm suffering a BAV and a moderate-severe AVS, for a couple of years ago, i'm monitoring my heartbeat during endurance training (=cycling) using my Polar rs800cx, wich can registrate every heartbeat from R-top to R-top.

After a lot of HR registrations after AVR from january 2011 (a month after AVR) until now (half a year post-op) i have noticed that my RR interval variations before surgery where much lower.

A short example of 10 heartbeats during exercise on +- HR 120 (=70% HRmax)
- Before AVR: 120-120-121-120-119-120-120-120-121-120
- After AVR: 120-125-120-126-121-126-119-125-120-127

Is there a simple explanation for this?

 

[CanoeBob]

I am a cyclist too as well I use a heart monitor. Cardio Rehab told me to keep my heart rate below 116 when exersizing. I take a beta blocker 12.5 mg atenol a day. When my heart rate goes over 120, weird things happen. Today did 60 km. average speed 18km hr, heart rate quite comfortable 100 to 108. Just glad to do 60 k, 7 mths after OHS, dont care how I rode before. Bob