Is there a relationship between kidney function and bradycardia?

None directly: The most likely way that renal function might affect bradycardia would be reduced elimination of medications that are cleared from the body by the kidneys such as digoxin or sotalol. As the kidney function worsens, the level of the medications build up in the blood, the heart rate slows, somtimes to dangerously slow rates.

No : Unless you are on a medication like atenolol which is renally cleared.