Research Projects

Trip Report: Left ventricular hypertrophy and risk of cardiac death in divers

We’ve just recently returned from the first field trip for the left ventricular hypertrophy and risk of cardiac death in divers study in Bonaire (August  31-September 7). For the first time, we field tested the study logistics and the protocol. The dive trip was organized by Down Under Surf & Scuba in Raleigh, N.C. Out of 36 subjects in the group, 25 were qualified participants over 40 years of age and actively participated in the study. Most of the baseline testing was completed prior to the trip in four sessions: two at DAN Headquarters and two at the dive shop. Five new subjects joined us from other parts of the country and were pre-screened upon arrival to Bonaire.


The Buddy Dive Resort was our central study location. They were very accommodating and allowed us to use their main classroom as a lab. The classroom was at the waterfront where most divers enter and exit water or board the boat for the boat dives.


 The plan was to get every participant scanned by echo twice after a full day of diving and once in the morning after a night’s rest. We took take a resting electrocardiogram (ECG) to monitor heart rate variability after a full day of diving on select dive days. All divers carried the Holter Monitor during at least one dive and were asked to record the depth and time of all their dives.


The compliance was nearly perfect. In fact, the only delays were related to travel time back from some remote dive sites. We completed a total of:

  • 100 echo scans
  • 50 resting ECGs
  • 24 underwater Holters
  • Nearly 500 recorded dives


The research team included cardiologist Dr. Douglas Ebersole, two professional echo cardiographers Brandy Emory of Lakeland Clinic and Lisa Caudill of Duke and myself. They did an excellent job maintaining the tight schedule and were well received by all of the participants. They even had time to join participants on some dives.

Scott Powell, the manager of Down Under Surf & Scuba and Rochelle Wright, a DAN Member Services specialist, managed all of the logistical challenges so we were able to complete our study. We’re very thankful for their support as well as the overwhelming support from the participants. We appreciate your participation and thank you for helping us to work toward improving diver safety.

Photography and Post by: Petar Denoble, MD, D.Sc.

Microparticles and DCS


Two studies presented by Steven Thom, one with divers and the other with isolated cells, indicate a role of inert gas under pressure in nitric oxide dependent oxidative stress response which results with microparticles (MP) and inflammation. Microparticles are linked to intravascular bubbles and the cell study seems to indicate that MPs come first and bubbles after (chicken or the egg). The human study provided less obvious answers. While this represents significant progress in elucidating cellular mechanisms involved in decompression sickness, it is far from a straight forward answer. DAN contributed to this study in collaboration with University of Split, Croatia. Sixteen divers volunteered in four dives each and provided blood samples before and after their dives. DAN specialists monitored their heart rate during the dive using an underwater ecg monitor and the presence of venous gas emboli postdive using echocardiography. Additional blood samples have been collected during field studies at Innerspace, a technical diving event in Grand Cayman. Analysis of this data is pending.

The full paper “Microparticle production, neutrophil activation, and intravascular bubbles following open-water SCUBA diving” is available online.

Post written by: Petar Denoble, MD, D.Sc.