The effectiveness of risk mitigation interventions in divers with persistent (patent) foramen ovale

Abstract

Introduction: Persistent (patent) foramen ovale (PFO) is a recognized risk for decompression sickness (DCS) in divers, which may be mitigated by conservative diving or by PFO closure. Our study aimed to compare the effectiveness of these two risk mitigation interventions. Methods: This was a prospective study on divers who tested positive for PFO or an atrial septal defect (ASD) and either decided to continue diving without closure ('conservative group'), or to close their PFO/ASD and continue diving ('closure group'). Divers' characteristics, medical history, history of diving and history of DCS were reported at enrollment and annually after that. The outcome measures were the incidence rate of DCS, frequency and intensity of diving activities, and adverse events of closure. Results: Divers in both groups dived less and had a lower incidence rate of confirmed DCS than before the intervention. In the closure group (n = 42) the incidence rate of confirmed DCS decreased significantly. Divers with a large PFO experienced the greatest reduction in total DCS. In the conservative group (n = 23), the post-intervention decrease in confirmed DCS incidence rate was not significant. Of note, not all divers returned to diving after closure. Seven subjects reported mild adverse events associated with closure; one subject reported a serious adverse event. Conclusions: PFO closure should be considered on an individual basis. In particular, individuals who are healthy, have a significant DCS burden, a large PFO or seek to pursue advanced diving may benefit from closure.

Risk mitigation in divers with persistent (patent) foramen ovale

“…In this issue, Anderson and colleagues report follow-up of divers who were found to have a persistent (patent) foramen ovale (PFO) or, in eleven cases, an atrial septal defect (ASD). 1 In most divers diagnosis followed an episode of decompression illness (DCI). The efficacy of closure of the PFO/ASD in preventing future DCI was compared with conservative diving.…”

“…The study by Anderson et al has a number of serious limitations. 1 The study was small with only 62 self-selected divers, who self-reported outcomes. Eleven divers had not had DCI when their PFO or ASD was detected.…”

Temporary and permanent unfitness of occupational divers. Brest Cohort 2002–2019 from the French National Network for Occupational Disease Vigilance and Prevention (RNV3P)

“…However, treating the PFO does not guarantee that no bubbles will pass through [26]. Before allowing diving to continue, especially for people who have had a DCS, it seems reasonable to discuss the benefit/risks balance of an intervention on a case-by-case basis [27]. It might be better for some divers to stop diving.…”

European position paper on the management of patients with patent foramen ovale. Part II - Decompression sickness, migraine, arterial deoxygenation syndromes and select high-risk clinical conditions

“…PFO-related DCS can produce earlier and more abundant VGE arterialisation but its role should be weighed against other individual factors that affect VGE production and trapping (dive/flight characteristics, physiological characteristics of tissues and factors that influence the threshold of "VGE tolerance"). Therefore, a technical analysis of the pre-decompression and decompression phase characteristics of each particular case is necessary 20 . In professional divers suffering from PFO-associated DCS, PFO size has been found to be a predictor of recurrence 21,22 .…”