Thanks for the helpful information. I am new at this message board so I responded in the wrong place I think. His doctor confirmed what you are saying about the heart rate. She said that is good and they want to keep it between 40 - 50. I was concerned since mine was so much higher!
Apparently, in the absence of symptoms (fatigue, difficulty breathing, etc) low heart rate is not considered problematic. Also, the causes of low heart rate as a function of cardiac physiology are varied. Again, consulting your cardiologist would be the best way to get a definitive answer.
Given that the range of the "normal" pulse is often given as 60-100, it may be that your husband's heart rate is lower than optimal. What does your husband's cardiologist say about the issue?
Also, one of the most common medications given for high blood pressure is beta blockers, which tend to slow the heart rate. Perhaps your husband is taking one of those.