>1- The likelihood of you having a syncopal episode while diving; and
>2- The likelihood of a sudden SVT causing myocardial ischemia while diving.
>SYNCOPAL EPISODE: As a rule of thumb, any medical condition (acute, chronic, congenital or acquired) known to potentially cause a sudden loss of consciousness (LOC) should be considered 'at least' as a relative contraindication to scuba dive. And I emphasize the 'at least' because this would depend on: (1) the likelihood of that happening; (2) the risks the diver is willing to take; and (3) the ethical and legal necessity of an informed consent to the crew members and the rest of the fellow divers diving with the individual. For example, an individual might be willing to take the risk to dive with a seizure disorder, but the likelihood of something happening is significantly higher than while not diving, the mortality of a sudden LOC is absurdly high, and the risk of third party injury and psychological stress and trauma for those trying to help is so unnecessary that even when an informed consent is due, the overall risk/benefit analysis calls for making such condition (seizure disorder) an absolute contraindication to practice scuba diving.
>So, if your doctors agree that the likelihood of a sudden LOC is negligible, then initially this should not necessarily be an absolute contraindication.
>MYOCARDIAL ISCHEMIA: Though the risks of a sudden death with a paroxysmal SVT are typically small, it is prudent to accept the fact that abnormal heart rhythms can have a life threatening impact in coronary artery perfusion. PSVT can result in myocardial ischemia, myocardial infarction, pulmonary edema, and heart failure in patients with poor left ventricular function. A heart stress test is the best way to assess someone's cardiovascular fitness. This functional test is also considered the best way to assess someone's cardiovascular fitness to dive, with its limitations, of course, for it does not account for the hemodynamic changes that take place during immersion, nor does it account for cold, peripheral vasoconstriction and increased breathing gas density; all of which may have a variable degree of relevance depending on the diving environment that it is to be pursued. Acceptable values for a heart stress test are probably a sustained workload of about 7-8 METs, tolerating peaks of up to 10 METs (this will make sense to your doctors).
>Author: Dr. Matias Nochetto MD