Diving with hypertrophic cardiomyopathy

I have been a dive instructor for more than 20 years. Last year I was diagnosed with hypertrophic cardiomyopathy; I do not take any medication for my condition, and I
have passed several tests, including a full stress test last February. About a month ago I met with my cardiologist to discuss my fitness to dive. My physician is pleased with my stress test results, and he reviewed my Recreational Scuba Training Council (RSTC) Medical Statement. After my exam he recommended that I exercise but avoid training that would increase my heart rate to more than 160 beats per minute for prolonged periods. He did not say that I couldn’t dive, but he said there is potential for increased risk if something happens to me while underwater. What is your professional medical opinion on this condition? Can I still dive?

A hypertrophic cardiomyopathy is not necessarily an absolute contraindication to scuba dive; it depends on how well your heart can perform under the physical demands typically
encountered on the type of diving you expect to be able to accomplish. First, you should define what type of diving you expect to be able to do, where you plan to dive and what you expect from diving.

RESEARCH, EDUCATION & MEDICINE
Type of diving:
The demands of a predictable and shallow tropical reef dive are not the same as those of a dive to the Andrea Doria. Thermal stress, dealing with currents, breathing dense gases, psychological stress and heavy equipment could significantly influence your cardiovascular demands.

Location:
The location of your dive directly correlates to the amount and severity of risks you are taking if anything goes wrong. There is a big difference between diving 30 minutes off the coast of Miami, Florida, where you have access to world-class medical facilities and
readily available emergency medical services (EMS) and diving off Vanuatu, where you are far from the closest reliable medical facilities in New Zealand or Australia.

Dive expectations:
If you are acting as a dive instructor, your demands are higher than  those of a diver who is simply enjoying a dive with a buddy. While diving for enjoyment, divers are responsible for their own well-being and at most the well-being of a dive buddy. As an instructor, you are responsible for all the divers following your lead, and you must be physically ready to make a rescue at any time to fulfil the duty of care you have to your students. Consider these requirements before you take on students, and the additional weight of a 131-foot (40-meter) vertical column of air, which is negligible. When a train is running through the tunnel, however, the air in front of the train is pushed and increases pressure, while the air behind the train is rarefied and causes decreased pressure.

This effect creates additional pressure above the car equal to 20 kPa (kilopascals) — the same amount of pressure a 6.5-foot (2-meter) column of water exerts, which would be unpleasant to passengers in the car. To alleviate this pressure, engineers created a sophisticated system of over pressure valves that keep the pressure difference down to 6 kPa (2 fsw, 0.6 msw). This constitutes all the additional pressure that passengers are exposed to during the ride and does not affect the decompression safety of divers. AD
— Petar Denoble, M.D., D.Sc.
Alert Diver Q1 2019