DAN Medical Frequently Asked Questions

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Issues Involving Coronary Artery Bypass Grafts

A coronary artery bypass is the surgical correction of a blockage in a coronary artery; it is accomplished by attaching (or "grafting") onto the damaged vessel a piece of a vein or artery from elsewhere in the body, so as to circumvent the blockage.

Doctors perform this procedure many hundreds of times a day, all around the country — more than half a million times a year. If a bypass is successful, the individual should be free of the symptoms of coronary artery disease, and the heart muscle should once again receive a normal supply of blood and thus oxygen.

A blocked coronary artery can also be treated with a less invasive procedure, coronary angioplasty. It consists of inserting a catheter with a tiny balloon on its tip into the area of the blockage, then inflating the balloon to open the artery. This procedure does not require opening the chest and can be performed in an outpatient setting.Individuals who have had a coronary artery bypass graft or coronary angioplasty may have suffered significant cardiac damage prior to having surgery. Their postoperative cardiac function is what determines their fitness for a return to diving.

In particular, those who have had open-chest surgery need to have a thorough medical evaluation prior to diving again. After a period of stabilization and healing (6 to 12 months is the usual recommendation), such individuals should have a complete cardiovascular evaluation before being cleared to dive. They should be free of chest pain and have a normal tolerance for exercise, as evidenced by a normal stress EKG test (at 13 METs, as described in "Calculating Physical Activity Intensity"). If there is any doubt about the success of the procedure, or how open the coronary arteries are, the individual should refrain from diving.

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