Cardiac Arrythmias in Scuba Divers

Heart issues are frequently implicated in scuba diving fatalities. Abnormal heartbeats, also known as arrythmias, can be a marker of cardiac compromise. This study follows 110 divers during six scuba diving trips and characterizes the factors that contribute to any post-diving arrythmias.

Diving fatalities are exceedingly rare, however, of the fatalities that do occur approximately 20 to 30 percent are caused by sudden cardiac death.

Sudden cardiac death, or SCD, is an abrupt, unexpected loss of heart function that results in fatality and often occurs in people who were previously presumed healthy. The exact mechanism that leads to SCD is unknown, but it is believed that a serious misfire in the heart’s rhythm, otherwise known as an arrythmia, is the culprit. A small amount of arrythmias are normal in daily life, but when they become more frequent, this can mean that the heart is impaired and that SCD is more likely.

Divers Alert Network is leading a study to characterize the factors that contribute to arrythmias in scuba divers to help prevent future cases of SCD. This study, currently in the analysis phase, consisted of six multi-day dive trips to gather data. Trip locations varied from a cold-water aquarium in the American Pacific Northwest, to the tropical Southern Caribbean, to a remote chain of islands in the Eastern Pacific Ocean.

One hundred and ten certified scuba divers signed up to be research subjects. Each provided basic biological information, medical history, diving history, and had their heart chambers measured by a diagnostic cardiac sonographer. Prior to dive trips, subjects’ heart rhythms were analyzed, and at the end of dive trips their heart rhythms were analyzed again. Arrythmias were identified and any changes between the pre-trip and post-trip scans were noted.

After the six trips were completed, the data were handed off for statistical analysis. While results are pending and cannot yet be shared with the general public, the preliminary findings are striking. DAN hopes that this study will serve as a template for future exploration into underwater physiology and will inspire future investigation on heart rhythm changes while scuba diving. When this study is published, DAN will publish a press release to alert all interested members of the research and dive communities.