The cardiovascular risks of diving.

Cardiovascular disease may be responsible for a quarter of diving fatalities, but there are few studies on the cardiovascular complications of this activity. In contrast, there is a rich literature on land-based, exercise-related cardiac events. These studies document that exercise can increase the risk of acute cardiac events, but that absolute risk is small for healthy individuals. There are no proven strategies to reduce exercise-related cardiac events and consequently no proven strategies that could be confidently applied to diving. Nevertheless, requiring a pre-diving medical evaluation and clearance for those with known cardiac disease, training dive personnel to elicit possible cardiac prodromal symptoms, and frequent emergency training for diving supervisors are prudent approaches to this problem.