My pulse if 48 right this very second. I am not concerned about it...
As long as you don't have symptoms with your slow heart rate, it's usually not a problem. Also, I assume your heart rate increases as it's supposed to do during exercise. If not, that may be a problem.
It's normal to see some throbbing on the neck/throat (the carotid artery) but you are not supposed to see any veins on your throat. If you do have dilated veins on your neck, you should see a doctor. If the veins (not the arteries) are pulsating heavily when your heart rate is slow, I recommend that you get an EKG taken when you have the symptoms.
Also, how is your blood pressure?
It may be a good idea to visit your GP for an evaluation, but this doesn't sound dangerous (I assume you refer to the carotid artery as "vein").