Having played professional basketball for ten years would seem to give Bradley an edge when it comes to being physically fit - something he and his doctors insist is still true despite the fact that he has atrial fibrillation.
"With the form of atrial fibrillation he has he has no heart disease and no risk factors for heart disease. There is not an increased risk for stroke," explained Bigger.
But in some cases atrial fibrillation can have serious consequences.
To pump blood efficiently the heart must send electrical signals from the upper chambers of the heart, called the atria, to the ventricles, which pump blood out to the body.
During atrial fibrillation the electrical activity is disorganized and the atria begin the quiver. As a result the ventricles beat more rapidly and less efficiently.
Symptoms can include palpitations, chest pain, lightheadedness, and weakness.
Diagnosed with the condition in 1996, Bradley has had five episodes of a-fib in the past month alone.
"He has a form of the atrial fibrillation called "paroxysmal," where it comes in a burst of episodes and it's just part of the natural history of this particular kind of atrial fibrillation," Bigger noted.
Each time his heart returned to normal without treatment. But on three occasions in the past his heart did not return to normal on its own and he had to undergo what is known as cardioversion.
"Cardioversion is a passing a quick electric shock across the chest to convert the atrial fibrillation to normal rhythm. He hasn't had this procedure in over a year and a half, however." explained Bigger, adding there is no damage from that process.
Bradley has said he may need to undergo cardioversion again in the future and has acknowledged that may mean he has to invoke the 25th Amendment if that occurs while president. That provision turns power over the vice-president during an incapacitation of the chief executive.
For many people this condition can be a nuisance if they go in and out of an abnormal rhythym, and there is a risk of stroke as a complication of a-fib if you do go in and out.
But most people can conduct their lives normally. It is not a life-threatening condition you can even qualify for a pilots license.
Bigger also noted that Bradley's particular form doesn't become more serious with age.
"His health is outstanding. He has no heart disease or risk factors for heart disease, no risk for stroke. He loves to exercise. He exercises regularly. He's an athlete, and has terrific exercise capacity," he adds.
The cause of his conition is unknown. Stress, caffeine, sleep deprivation, dehydration among a whole host of other things are said to bring it on. The problem initially can occur after a heart attack, but in some cases the cause is just unknown.
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