This post was authored by Alfred A. Bove, MD, PhD, MACC, member of the ACC’s Sports and Exercise Cardiology section leadership council.

Within the spectrum of sports and exercise cardiology is sports scuba diving. There are unique and interesting cardiology issues related to undersea exposures. Examples include when a female sport diver develops a Takotsubo syndrome after being stung by a toxic jelly fish, or when a commercial diver is shocked by an electric ray and develops atrial fibrillation. Others examples include when a healthy 30-year-old female diver develops dyspnea, cough and blood tinged frothy sputum while diving and is found to be in pulmonary edema. These are a few of the disorders that occur in sport divers in which a cardiologist is often consulted. Recently, my institution (Temple University School of Medicine) sponsored a one-week continuing medical education program in undersea medicine. This was our 40th consecutive program, and this year we covered topics on the physics and physiology of diving and underwater exposure, hazardous marine life, breath hold diving, submarine escape and rescue, cardiac fitness to dive, and sudden death in diving. 

There was a particular interest related to cardiac disorders including diving following coronary revascularization, the role of right to left shunts in decompression sickness disorders, immersion pulmonary edema, diving while taking anticoagulants for atrial fibrillation, diving with pacemakers and implantable cardioverter-defibrillators, diving after correction of Tetralogy of Fallot, diving with a Fontan conduit, and the interesting long QT syndrome that is aggravated by swimming and water immersion.

Scuba diving is one of the few sports where certification is required to participate in an organized recreational diving activity, and the certification involves education about the physics of underwater exposure, the physiology involved and the pathophysiology related to diving exposures. However, once certified, there are no subsequent requirements to demonstrate proficiency. Many divers develop cardiac disorders as they age, but still hold a certification that allows them to participate in the sport.  Most organized recreational diving operations require not only a certification, but most also require the divers to sign a health form that states that they are in good health. Many divers will seek approval letters from their physicians to demonstrate that they are capable of safe diving, and often seek such letters from their cardiologist if their particular disorder is cardiac related.

Diving does require exercise. Usual expenditures are 3-4 mets, but a 6-7 met demand may occur in adverse conditions such as currents and rough seas. A good rule of thumb is that steady state exercise capacity should be about half of maximum capacity, so a peak capacity on a treadmill test should be between 12 and 14 mets if the diver expects to safely withstand adverse conditions, otherwise there should be a plan for assistance when needed. Water immersion results in a 600-700 ml central shift of blood and produces an acute volume load on the heart. Individuals with compromised cardiac function can develop heart failure symptoms just from being immersed in water to the neck. On the other hand, immersion and swimming induced pulmonary edema are phenomena related to normal cardiac function, are multifactorial and not associated with identified cardiac dysfunction.

While the usual request of a cardiologist might be related to evaluation of athletes, or adults who are participating in land-based sport activity, there is an occasional diver who seeks cardiology consultation for a known or perceived cardiac disorder. We should be aware of the unique environment that sport divers encounter and the relationship of the diving environment to a variety of cardiac disorders. More information about this topic can be found at SCUBAMED.com.

This post is part of a series of posts from the ACC’s Sports and Exercise Cardiology Section. For more information about the Section, click here.  

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