Dive Doctor: Heart of a Diver

Q. I am 31-year-old diver. One year ago I had a massive heart attack and a six-vessel cardiac bypass. Tests showed I was fortunate and only had minimal heart damage (less than 5 percent). Otherwise, I am in good health and have had no further heart problems. I have planned a Caribbean vacation and want to scuba dive. I would like to know what my maximum depth should be. A: Today, having had a heart attack and a coronary artery bypass operation is not a contraindication to diving if the following issues are addressed. First, any injury to the heart must be minimal enough so that your exercise capacity is not limited in any way. If you can exercise to 13 METS (metabolic equivalents) without any problems during an exercise stress test, you should be OK. In addition, there must be no sign of ischemia - insufficient oxygen delivery to the heart muscle. The heart rhythm must also be normal, without signs of irritability. Since grafts can, over time, narrow again, it is essential that you have regular visits and tests with your cardiologist. He can then decide if diving or other activities can be continued. As far as maximum depth is concerned, most physicians would recommend a non-stressful dive environment. A 100-foot dive in clear, warm water in the Caribbean would be less stressful than a 40-foot dive in a drysuit in cold water against a current.Q. If I have not been diving for some time and return to it, I sometimes feel while at depth as if I will faint and my heart will beat unusually hard and become slow. At that moment I ascend and the symptoms subside. I have had my heart checked for any irregular rhythms, but none were found. Is this related to the way I breathe or possibly due to some bad breathing habit that I may have developed? A: Divers with tight-fitting wetsuit neck seals (or anyone with a tight collar, for that matter) can experience compression of the carotid artery in the neck. This will generate the symptoms you have described. It is also known that cold water can induce irregular heartbeats and rhythms. Though you mentioned your heart was checked for an irregular rhythm and found to be normal, you may wish to consult with a cardiologist. While a standard electrocardiogram is useful, a 24-hour rhythm check, known as a Holter monitor, is a more thorough means of checking for any irregular heart rhythms.