My heart rate has remained quite similar to what is was before. My hematocrit / hemoglobin levels are also about the same as they have always been - middle of the normal range, although I've never had it tested during or immediately after exercise. My resting heart rate is higher than it used to be (was upper-30s, now mid-40s), and my max HR is now 170. Threshold HR is 150-155. I always had a relatively low heart rate, so other than a higher resting heart rate, that's about where it should be.
I've never used a pulse oximeter during a ride. I didn't know that they were so readily available! That might be a very useful tool for me considering what I'm fighting. That would answer the question as to whether the strong tingling sensations I get during 1-minute intervals is in fact hypoxia. I can't believe that, as involved as I am in this sport, I never heard people discuss using one!
There was a lot of damage around the LAD. The way my heart compensated was to significantly enlarge the left ventricle. So, instead of having a normal "athletic" heart, I now have a VERY large and inefficient left ventricle. I went from a modern V6 turbo to a 60's V8 - doesn't make as much power, and burns a whole lot more gas in the process!
Dave