Causes of a low pulse rate include high blood pressure, underactive thyroid gland, heart surgery complications, infection of heart tissues and inflammatory disease such as lupus, states Mayo Clinic. A low pulse rate can sometimes be normal but can also be a symptom of a problem with the heart's electrical system.
A low pulse rate results from the disruption of the normal electrical impulses that control the rate at which the heart pumps blood. The pulse rate may lower due to aging or diseases that interrupt the heart's electrical system such as heart attack. An electrolyte imbalance, a low thyroid level and medicine for treating hypertension, such as digoxin and anti-arrhythmics, also cause this condition, notes WebMD.
For some people, like athletes and young adults, a low pulse rate is a sign of being physically fit, explains WebMD. In others, this condition means that the electrical system of the heart has a problem, pumping an insufficient amount of blood to body parts. A low pulse rate may cause an inadequate supply of oxygen to the brain and other organs, leading to symptoms such as confusion, shortness of breath, chest pains and fainting. Patients experiencing these signs should seek medical attention, stresses Mayo Clinic.