Ed Klein writes,
…Sources close to Hillary tell me that her doctors have discovered she suffers from arrhythmia (an abnormal heart beat) and a leaking heart valve. They have recommended that she consider having valve replacement surgery, but Hillary has refused because she does not want to risk the negative political fallout from stories about such a serious operation.
In addition to the arrhythmia and leaking heart valve, Hillary suffers from chronic low blood pressure, insufficient blood flow, a tendency to form life-threatening blood clots, and troubling side effects from her medications.
Her doctors have prescribed Coumadin, a blood thinner, and a beta blocker to treat her condition. However, these medications make her drowsy and tired, lower her blood pressure, and have led to frequent bouts of light-headedness and fainting spells.
Read more here.