An abnormally slow heart beats that results either form disease that affects the natural pacemaker of the heart or the wire that conducts the impulse from the upper chambers to the lower chambers.
This can sometimes cause symptoms such as dizziness, fatigue and shortness of breath and if it is severe enough it can cause passing out spells, which is potentially dangerous.
There is no medications that you can increase the heart beats on the long run.
Sometimes if this condition is causing symptoms or if your doctor thinks that it might progress , he may recommend that you have a pacemaker implanted to prevent the heart beats from slowing down.