I wasn't focusing simply on heart rate, rather I was more focused on increasing flexibility and widening blood vessels in the upper body, which remain so after the exercise (after a period of time doing said exercise), just like a cyclist's blood vessels in the legs are more flexible and wider than most people.
I'm sorry - but there are many other factors contributing to blood vessel health more than using muscles in a particular limb.
Tracking your overall "volume of aerobic activity" is as good as any possible metric that could be associated with blood vessel health. But in reality, hormonal, genetic, dietary and hematological factors significant bearings on systemic circulatory health, including the arms or legs.
Anyway - keep at it.