Decompression Sickness Risk Stratification in Divers With PFO

Quick Takes

  • A screening and risk stratification strategy was associated with decreased decompression sickness occurrence in divers with patent foramen ovale.
  • Patients with high-grade shunts continued to have higher risk of decompression sickness despite recommendations for conservative dive profiles.

Study Questions:

What is the occurrence of decompression sickness (DCS) after the application of a patent foramen ovale (PFO) screening and risk stratification strategy?


The DIVE-PFO (Decompression Illness Prevention in Divers With a Patent Foramen Ovale) registry was used. Shunts were detected using transcranial color-coded sonography and graded as grade 1 (1-10 bubbles), grade 2 (>10 bubbles but no curtain; uncountable number of bubbles), or grade 3 (curtain). Grade 1 and 2 shunts were considered low-grade, while grade 3 shunts were considered high-grade. Divers with a high-grade PFO were offered either catheter-based PFO closure or a conservative diving strategy. Divers with low-grade shunt were advised a conservative diving strategy, while those with no shunt continued unrestrictive guideline and made up the control group. A telephone follow-up was performed, and DCS occurrence before enrollment and during the follow-up was compared.


A total of 829 consecutive divers (mean age 35.4 ± 10 years, 81.5% male) were screened, of which follow-up was available for 748 (90%). The mean follow-up was 6.5 ± 3.5 years. The DCS incidence decreased in all groups except the controls. During follow-up, there were no DCS events in the closure group; DCS incidence in the low-grade shunt group was similar to the controls (hazard ratio [HR], 3.965; 95% confidence interval [CI], 0.558-28.18; p = 0.169) but remained higher in the high-grade group (HR, 26.17; 95% CI, 5.797-118.16; p < 0.0001).


The authors concluded that a screening and risk stratification strategy using transcranial color-coded sonography was associated with a decrease in DCS occurrence in divers with PFO. The DCS incidence remained higher in the high-grade group than all other groups, despite the use of conservative diving strategies.


PFO has been well established as a risk factor for DCS in divers. This study used a registry of divers to assess the impact of a PFO screening program on the incidence of DCS. The study demonstrated that divers with smaller shunts did not have increased risk with the use of a conservative dive strategy. Conservative dive profiles involve limiting the maximum depth, dive time, or number of dives per day. Additionally, a slower ascent rate and safety stops are recommended. Despite conservative dive profiles, patients with large shunts (bubbles too numerous to count) remained at increased risk for DCS. Cardiologists may become involved in the pre-dive evaluation of patients with existing intracardiac shunts. This study supports consideration for restriction from diving or PFO closure for patients with high-grade shunts.

Clinical Topics: Cardiovascular Care Team, Congenital Heart Disease and Pediatric Cardiology, Noninvasive Imaging, Prevention, Sports and Exercise Cardiology, Congenital Heart Disease, CHD and Pediatrics and Arrhythmias, CHD and Pediatrics and Imaging, CHD and Pediatrics and Prevention, CHD and Pediatrics and Quality Improvement, Echocardiography/Ultrasound, Sports and Exercise and Congenital Heart Disease and Pediatric Cardiology, Sports and Exercise and Imaging

Keywords: Cardiac Catheters, Decompression, Decompression Sickness, Diving, Foramen Ovale, Patent, Heart Defects, Congenital, Risk Assessment, Risk Factors, Secondary Prevention, Ultrasonography

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