The walls of the arteries, in response to the deposition of fatty material, also thicken. The result is a progressive reduction in the flow of blood through the affected vessels. These effects are especially damaging in the heart; CAD is the leading cause of death in the United States and other industrialized countries.
Many factors contribute to the development of atherosclerosis, including a diet high in fat and cholesterol, smoking, hypertension, increasing age and a family history of the condition. Women of reproductive age are generally at lower risk of atherosclerosis due to the protective effects of estrogen.
Medications typically used to treat atherosclerosis include nitroglycerin (which is also used in the treatment of angina, or chest pain) and calcium channel blockers and beta blockers (which are also used in the treatment of high blood pressure, or hypertension; see "Antihypertensives" for more on these drugs). Sometimes, individuals with CAD may need what's known as a revascularization procedure, to re-establish the blood supply — typically a coronary artery bypass graft or angioplasty. If such a procedure is successful, the individual may be able to return to diving after a period of healing and a thorough cardiovascular evaluation (see "Issues Involving Coronary Artery Bypass Grafts.").
Effect on DivingSymptomatic coronary artery disease is not consistent with safe diving: don't dive if you have CAD. The condition results in a decreased delivery of blood — and therefore oxygen — to the muscular tissue of the heart. Exercise increases the heart's need for oxygen. Depriving your heart of oxygen can lead to abnormal heart rhythms and/or myocardial infarction, (a heart attack). The classic symptom of CAD is chest pain, especially following exertion. But unfortunately, many people have no symptoms before they experience a heart attack.
A history of stroke — or of "mini strokes" known as transient ischemic attacks (TIAs) — are also, in most cases, not consistent with safe diving.
Cardiovascular disease is a significant cause of death among divers. Older divers and those with significant risk factors for coronary artery disease should have regular medical evaluations and undergo appropriate screening studies, such as a treadmill stress test.