Persistent foramen ovale closure in divers with a history of decompression sickness

Patent Foramen Ovale and Decompression Illness: The Present and Future

Presence of patent foramen ovale (PFO), particularly if high-grade, increases the risk of decompression illness (DCI) and its severe forms. In unprovoked or recurrent DCI, neurologic, cutaneous, or cardiopulmonary DCI, testing for PFO is indicated with bubble contrast echocardiography or transcranial Doppler using provocative maneuvers. In patients with PFO and history of DCI, evaluation by a cardiologist with expertise in diving medicine is recommended. Consideration should be given to PFO closure if cessation of diving or conservative diving cannot be achieved. Prospective studies evaluating long-term outcomes in patients who continue to dive after PFO closure are required.

Updates on Patent Foramen Ovale (PFO) Closure

PURPOSE OF REVIEW

Patent foramen ovale (PFO) has been previously linked to left circulation thromboembolism and stroke. This review article aims to discuss the latest evidence, updated societal guidelines, diagnostic algorithms and novel therapeutic devices for PFO closure.

RECENT FINDINGS

PFO closure for cryptogenic stroke and systemic embolization is supported by a large body of evidence and has a strong societal recommendation. Limited data are available for platypnea-orthodeoxia syndrome, although closure appears to be beneficial. Current data do not support routine closure for migraines and decompression Illness. Development of heart-brain teams can improve identification of patients most likely to benefit from closure, utilizing a combination of imaging test and risk score algorithms. Multiple novel devices aiming at reducing complications and improving the long-term impact of current available devices are being evaluated. PFO closure has significantly progressed over the last years, with new data supporting its superiority in reducing risk of recurrent embolic stroke in patients with PFO-related stroke. Additional clinical data are required to provide further refinements on patient selection and guidance on treatment of specific subgroups.

Patent Foramen Ovale Closure in Special Clinical Situations: More Questions Than Answers?

Patent foramen ovale (PFO) is a remnant of the foetal circulation resulting from incomplete occlusion of the septum primum and septum secundum. Although prevalent in about 25% of the population, it mainly remains asymptomatic. However, its clinical significance in situations such as cryptogenic stroke, migraine, and decompression illness (DCI) has been well described. Recent randomised clinical trials (RCTs) have demonstrated the efficacy of percutaneous PFO closure over pharmacological therapy alone for secondary stroke prevention in carefully selected patients. Notably, these trials have excluded older patients or those with concurrent thrombophilia. Furthermore, the role of closure in other clinical conditions associated with PFO, like decompression sickness (DCS) and migraines, remains under investigation. Our review aims to summarise the existing literature regarding epidemiology, pathophysiological mechanisms, optimal management, and closure indications for these special patient groups.

Decompression illness: a comprehensive overview

Decompression illness is a collective term for two maladies (decompression sickness [DCS] and arterial gas embolism [AGE]) that may arise during or after surfacing from compressed gas diving. Bubbles are the presumed primary vector of injury in both disorders, but the respective sources of bubbles are distinct. In DCS bubbles form primarily from inert gas that becomes dissolved in tissues over the course of a compressed gas dive. During and after ascent ('decompression'), if the pressure of this dissolved gas exceeds ambient pressure small bubbles may form in the extravascular space or in tissue blood vessels, thereafter passing into the venous circulation. In AGE, if compressed gas is trapped in the lungs during ascent, pulmonary barotrauma may introduce bubbles directly into the pulmonary veins and thence to the systemic arterial circulation. In both settings, bubbles may provoke ischaemic, inflammatory, and mechanical injury to tissues and their associated microcirculation. While AGE typically presents with stroke-like manifestations referrable to cerebral involvement, DCS can affect many organs including the brain, spinal cord, inner ear, musculoskeletal tissue, cardiopulmonary system and skin, and potential symptoms are protean in both nature and severity. This comprehensive overview addresses the pathophysiology, manifestations, prevention and treatment of both disorders.

Approval, Evidence, and "Off-Label" Device Utilization: The Patent Foramen Ovale Closure Story

BACKGROUND

Following regulatory approval, medical devices may be used "off-label." Patent foramen ovale (PFO) closure is indicated to reduce recurrent stroke but has been proposed for other indications, including migraine, transient ischemic attack, and diving decompression illness. We sought to evaluate PFO closure rates and indications relative to the timing of regulatory approval and publication of key randomized trials.

METHODS

We performed a retrospective cohort study using the OptumLabs Data Warehouse of US commercial insurance enrollees from 2006 to 2019. We quantified PFO closure among individuals with ≥2 years of preprocedure coverage to establish indications, classified hierarchically as stroke/systemic embolism, migraine, transient ischemia attack, or other.

RESULTS

We identified 5315 patients undergoing PFO closure (51.8% female, 29.2%≥60 years old), which increased from 4.75 per 100 000 person-years in 2006 to 6.60 per 100 000 person-years in 2019. Patients aged ≥60 years accounted for 29.2% of closures. Procedure volumes corresponded weakly with supportive clinical publications and device approval. Among patients with PFO closure, 58.6% underwent closure for stroke/systemic embolism, 10.2% for transient ischemia attack, 8.8% for migraine, and 22.4% for other indications; 17.6% of patients had atrial fibrillation at baseline; and 11.9% developed atrial fibrillation postprocedure. Those aged ≥60 years and male were less likely to undergo closure for migraine than stroke/systemic embolism.

CONCLUSIONS

From 2006 to 2019, PFO closure use was consistently low and corresponded weakly with clinical trial publications and regulatory status. Nearly half of patients underwent PFO closure for indications unapproved by the Food and Drug Administration. Regulators and payers should coordinate mechanisms to promote utilization for approved indications to ensure patient safety and should facilitate clinical trials for other possible indications.

Atypical distally distributed cutis marmorata decompression sickness associated with unconventional use of thermal protection in a diver with persistent foramen ovale

Cutis marmorata is a mottled, marbling, livedoid rash caused by vascular inflammation and congestion in cutaneous decompression sickness. It may occur during or after ascent due to the formation of bubbles from dissolved nitrogen accumulated throughout the dive. It is strongly associated with the presence of right to left shunts, particularly persistent (patent) foramen ovale (PFO). We report a case of cutis marmorata decompression sickness of an unusual pattern associated with unconventional use of thermal protection (a 'shorty' wetsuit worn over full suit) by a diver with a PFO. The patient also had neurological manifestations of decompression sickness. The distal lower limb pattern of involvement favours the hypothesis that cutis marmorata in humans is likely to be due to bubbles in the skin itself and/or adjacent tissues rather than cerebrally mediated.

SCUBA Diving in Adult Congenital Heart Disease

Conventionally, scuba diving has been discouraged for adult patients with congenital heart disease (ACHD). This restrictive sports advice is based on expert opinion in the absence of high-quality diving-specific studies. However, as survival and quality of life in congenital heart disease (CHD) patients have dramatically improved in the last decades, a critical appraisal whether such restrictive sports advice is still applicable is warranted. In this review, the cardiovascular effects of diving are described and a framework for the work-up for ACHD patients wishing to engage in scuba diving is provided. In addition, diving recommendations for specific CHD diagnostic groups are proposed.

The management of patent foramen ovale in divers: where do we stand?

Diving is a fascinating activity, but it does not come without any cost; decompression illness (DCI) is one of the most frequent diseases occurring in divers. Rapid surfacing after diving causes alveolar rupture and bubbles release, which enter in the systemic circulation and could embolize numerous organs and tissues. The presence of patent foramen ovale (PFO) contributes to the passage of venous gas bubbles into the arterial circulation, increasing the risk of complications related to DCI. The diagnosis is established with a detailed medical history, a comprehensive clinical evaluation, and a multimodal imaging approach. Although the percutaneous closure of PFO is ambiguous for divers, as a primary prevention strategy, transcatheter management is considered as beneficial for DCI recurrence prevention. The aim of this study is to introduce the basic principles of DCI, to review the pathophysiological connection between DCI and PFO, to highlight the risk factors and the optimal treatment, and, last but not least, to shed light on the role of closure as primary and secondary prevention.

SCAI Technical Review on Management of Patent Foramen Ovale

Background

Patent foramen ovale (PFO) is a common anatomic variant associated with intermittent right-to-left shunting. Transcatheter PFO closure has been proposed to address multiple clinical conditions including stroke, transient ischemic attack, migraine, and decompression illness.

Methods

A systematic review was conducted using the GRADE approach to address 5 questions formulated by the Society for Cardiovascular Angiography and Interventions (SCAI) Guideline Panel in patient, intervention, comparator, outcome (PICO) format. Medical literature from January 2015 through May 2021 was searched. Extracted data underwent review and risk-of-bias assessment by 2 independent researchers. Pooled effect estimates were calculated. Certainty of evidence was determined for each query.

Results

Our search identified 2701 titles and abstracts, of which 30 met eligibility criteria and informed the technical review. Data were abstracted to address outcomes of PFO closure for patients with and without prior stroke, in comparison to antiplatelet therapy, in comparison to anticoagulation, and with various post-procedure antithrombotic regimens.

Conclusion

In appropriately selected patients with prior stroke, transcatheter PFO closure reduces the risk of recurrent stroke more than antiplatelet therapy alone. Evidence to support PFO closure is weaker regarding older patients, anticoagulation, thrombophilia, transient ischemic attack, migraine, and decompression illness. Data from this technical review will inform the SCAI Guideline for Transcatheter Patent Foramen Ovale Closure.

SCAI Guidelines for the Management of Patent Foramen Ovale

Background

Patent foramen ovale (PFO) is a vestigial congenital cardiovascular structure present in around 25% of adults. In most cases, PFO is entirely benign and requires no treatment. However, it may cause serious complications under certain circumstances.

Objective

These evidence-based guidelines from the Society for Cardiovascular Angiography and Interventions (SCAI) aim to support patients, clinicians, and other stakeholders in decisions about management of PFO.

Methods

SCAI convened a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The Evidence Foundation, a registered 501(c)(3) nonprofit organization, provided methodological support for the guideline-development process. Following the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, the guideline panel formulated and prioritized clinical questions in population, intervention, comparison, outcome (PICO) format. A separate technical review team of clinical and methodological experts conducted systematic reviews of the evidence, synthesized data, and graded the certainty of the evidence across outcomes. The guideline panel then reconvened to formulate recommendations and supporting remarks informed by the results of the technical review and additional contextual factors described in the GRADE evidence-to-decision framework.

Results

The panel agreed on 13 recommendations to address variations on 5 clinical scenarios.

Conclusions

Key recommendations address patient selection for PFO closure in the prevention of recurrent PFO-associated stroke, including populations not commonly included in randomized studies, and scenarios where the PFO closure might serve a role in the prevention of other outcomes such as migraine headaches and decompression illness. The panel has also identified future research priorities to advance the field.

Patent Foramen Ovale Closure and Decompression Sickness Among Divers

BACKGROUND

Decompression sickness is a diving-related disease that results in various clinical manifestations, ranging from joint pain to severe pulmonary and CNS affection. Complications of this disease may sometimes persist even after treatment with hyperbaric oxygen therapy. In addition, it may hamper the quality of life by forcing divers to restrict their recreational practice. The presence of a patent foramen ovale (PFO) increases the risk of decompression sickness by facilitating air embolization. Therefore, PFO closure may play a role in reducing such complications. However, PFO closure remains associated with its own set of risks and complications. We sought to assess the benefit and harm of PFO closure for the prevention of decompression sickness in divers.

METHODS

We conducted a comprehensive search of MEDLINE, Embase, CENTRAL, and Web of Science. Two-armed studies comparing the incidence of decompression sickness with or without PFO closure were included. We used a random-effects model to compute risk ratios comparing groups undergoing PFO closure to those not undergoing PFO closure.

RESULTS

Four observational studies with a total of 309 divers (PFO closure: 141 and no closure: 168) met inclusion criteria. PFO closure was associated with a significantly lower incidence of decompression sickness (PFO-closure: 2.84%; no closure: 11.3%; RR: 0.29; 95% CI: 0.10 to 0.89; NNTB = 11), with low heterogeneity (I2 = 0%). The mean follow-up was 6.12 years (Standard deviation 0.70). Adverse events occurred in 7.63% of PFO closures, including tachyarrhythmias and bleeding.

CONCLUSION

PFO closure may potentially reduce the risk of decompression sickness among divers; however, it is not free of potential downsides, with nearly one in thirteen patients in our analysis experiencing an adverse event.

Increased Risk of Decompression Sickness When Diving With a Right-to-Left Shunt: Results of a Prospective Single-Blinded Observational Study (The "Carotid Doppler" Study)

Introduction: Divers with a patent Foramen Ovale (PFO) have an increased risk for decompression sickness (DCS) when diving with compressed breathing gas. The relative risk increase, however, is difficult to establish as the PFO status of divers is usually only determined after a DCS occurrence.

Methods: This prospective, single-blinded, observational study was designed to collect DCS data from volunteer divers after screening for right-to-left shunt (RLS) using a Carotid Doppler test. Divers were blinded to the result of the test, but all received a standardized briefing on current scientific knowledge of diving physiology and “low-bubble” diving techniques; they were then allowed to dive without restrictions. After a mean interval of 8 years, a questionnaire was sent collecting data on their dives and cases of DCS (if any occurred).

Results: Data was collected on 148 divers totaling 66,859 dives. There was no significant difference in diving data between divers with or without RLS. Divers with RLS had a 3.02 times higher incidence of (confirmed) DCS than divers without RLS (p = 0.04). When all cases of (confirmed or possible DCS) were considered, the Relative Risk was 1.42 (p = 0.46). DCS occurred mainly in divers who did not dive according to “low-bubble” diving techniques, in both groups.

Conclusion: This prospective study confirms that DCS is more frequent in divers with RLS (such as a PFO), with a Relative Risk of 1.42 (all DCS) to 3.02 (confirmed DCS). It appears this risk is linked to diving behavior, more specifically diving to the limits of the adopted decompression procedures.

Screening and Risk Stratification Strategy Reduced Decompression Sickness Occurrence in Divers With Patent Foramen Ovale

OBJECTIVES

This paper sought to evaluate the occurrence of decompression sickness (DCS) after the application of a patent foramen ovale (PFO) screening and risk stratification strategy.

BACKGROUND

PFO is associated with an increased risk of DCS. Recently, transcatheter closure was reported to reduce DCS occurrence in divers with a high-grade shunt. However, to date, there are no data regarding the effectiveness of any PFO screening and risk stratification strategy for divers.

METHODS

A total of 829 consecutive divers (35.4 ± 10.0 years, 81.5% men) were screened for PFO by means of transcranial color-coded sonography in the DIVE-PFO (Decompression Illness Prevention in Divers with a Patent Foramen Ovale) registry. Divers with a high-grade PFO were offered either catheter-based PFO closure (the closure group) or advised conservative diving (high grades). Divers with a low-grade shunt were advised conservative diving (low grades), whereas those with no PFO continued unrestricted diving (controls). A telephone follow-up was performed. To study the effect of the screening and risk stratification strategy, DCS occurrence before enrollment and during the follow-up was compared.

RESULTS

Follow-up was available for 748 (90%) divers. Seven hundred and 2 divers continued diving and were included in the analysis (mean follow-up 6.5 ± 3.5 years). The DCS incidence decreased significantly in all groups, except the controls. During follow-up, there were no DCS events in the closure group; DCS incidence was similar to the controls in the low-grade group (HR: 3.965; 95% CI: 0.558-28.18; P = 0.169) but remained higher in the high-grade group (HR: 26.170; 95% CI: 5.797-118.16; P < 0.0001).

CONCLUSIONS

The screening and risk stratification strategy using transcranial color-coded sonography was associated with a decrease in DCS occurrence in divers with PFO. Catheter-based PFO closure was associated with a DCS occurrence similar to the controls; the conservative strategy had a similar effect in the low-grade group, but in the high-grade group the DCS incidence remained higher than in all other groups.

Patent Foramen Ovale-A Not So Innocuous Septal Atrial Defect in Adults

Patent foramen ovale (PFO) is a common congenital atrial septal defect with an incidence of 15-35% in the adult population. The development of the interatrial septum is a process that begins in the fourth gestational week and is completed only after birth. During intrauterine life, the foramen ovale allows the passage of highly oxygenated blood from the right to the left atrium and into the systemic arteries, thus bypassing the pulmonary circulation. In 75% of the general population, the foramen ovale closes after birth, and only an oval depression, called fossa ovalis, remains on the right side of the interatrial septum. Patent foramen ovale can be associated with various clinically important conditions, including migraine and stroke, or decompression illness in divers. The aim of this review is to summarize the PFO developmental and anatomical features and to discuss the clinical risks associated with this atrial septal defect in adults.

Decompression sickness after a highly conservative dive in a diver with known persistent foramen ovale: Case report

A diver returned to diving, 15 months after an episode of neuro-spinal decompression sickness (DCS) with relapse, after which she had been found to have a moderate to large provoked shunt across a persistent (patent) foramen ovale (PFO), which was not closed. She performed a single highly conservative dive in line with the recommendations contained in the 2015 position statement on PFO and diving published jointly by the South Pacific Underwater Medicine Society and the United Kingdom Sports Diving Medical Committee. An accidental Valsalva manoeuvre shortly after surfacing may have provoked initial symptoms which later progressed to DCS. Her symptoms and signs were milder but closely mirrored her previous episode of DCS and she required multiple hyperbaric oxygen treatments over several days, with residua on discharge. Although guidance in the joint statement was mostly followed, the outcome from this case indicates that there may be a subgroup of divers with an unclosed PFO, who have had a previous episode of serious DCS, who may not be safe to dive, even within conservative limits.

Does persistent (patent) foramen ovale closure reduce the risk of recurrent decompression sickness in scuba divers?

INTRODUCTION

Interatrial communication is associated with an increased risk of decompression sickness (DCS) in scuba diving. It has been proposed that there would be a decreased risk of DCS after closure of the interatrial communication, i.e., persistent (patent) foramen ovale (PFO). However, the clinical evidence supporting this is limited.

METHODS

Medical records were reviewed to identify Swedish scuba divers with a history of DCS and catheter closure of an interatrial communication. Thereafter, phone interviews were conducted with questions regarding diving and DCS. All Swedish divers who had had catheter-based PFO-closure because of DCS were followed up, assessing post-closure diving habits and recurrent DCS.

RESULTS

Nine divers, all with a PFO, were included. Eight were diving post-closure. These divers had performed 6,835 dives (median 410, range 140-2,200) before closure, and 4,708 dives (median 413, range 11-2,000) after closure. Seven cases with mild and 10 with serious DCS symptoms were reported before the PFO closure. One diver with a small residual shunt suffered serious DCS post-closure; however, that dive was performed with a provocative diving profile.

CONCLUSION

Divers with PFO and DCS continue to dive after PFO closure and this seems to be fairly safe. Our study suggests a conservative diving profile when there is a residual shunt after PFO closure, to prevent recurrent DCS events.

A review of diving practices and outcomes following the diagnosis of a persistent (patent) foramen ovale in compressed air divers with a documented episode of decompression sickness

INTRODUCTION

The presence of a persistent (patent) foramen ovale (PFO) increases the risk of decompression sickness (DCS) whilst diving with pressurised air. After the diagnosis of a PFO, divers will be offered a number of options for risk mitigation. The aim of this study was to review the management choices and modifications to diving practices following PFO diagnosis in the era preceding the 2015 joint position statement (JPS) on PFO and diving.

METHODS

A retrospective study was conducted of divers sourced from both the Alfred Hospital, Melbourne and the Divers Alert Network Asia-Pacific during the period 2005-2015. Divers were contacted via a combination of phone, text, mail and email. Data collected included: diving habits (years, style and depths); DCS symptoms, signs and treatment; return to diving and modifications of dive practices; history of migraine and echocardiography (ECHO) pre- and post-intervention; ECHO technique(s) used, and success or failure of PFO closure (PFOC). Analyses were performed to compare the incidence of DCS pre- and post-PFO diagnosis.

RESULTS

Seventy-three divers were interviewed. Sixty-eight of these returned to diving following the diagnosis of PFO. Thirty-eight underwent PFOC and chose to adopt conservative diving practices (CDPs); 15 chose PFOC with no modification to practices; 15 adopted CDPs alone; and five have discontinued diving. The incidence of DCS decreased significantly following PFOC and/or adoption of conservative diving practices. Of interest, migraine with aura resolved in almost all those who underwent PFOC.

CONCLUSIONS

Many divers had already adopted practices consistent with the 2015 JPS permitting the resumption of scuba diving with a lowering of the incidence of DCS to that of the general diving population. These results support the recommendations of the JPS.

South Pacific Underwater Medicine Society guidelines for cardiovascular risk assessment of divers

The South Pacific Underwater Medicine Society (SPUMS) diving medical for recreational scuba divers was last reviewed in 2011. From 2011 to 2019, considerable advancements have occurred in cardiovascular risk assessment relevant to divers. The SPUMS 48th (2019) Annual Scientific Meeting theme was cardiovascular risk assessment in diving. The meeting had multiple presentations updating scientific information about assessing cardiovascular risk. These were distilled into a new set of guidelines at the final conference workshop. SPUMS guidelines for medical risk assessment in recreational diving have subsequently been updated and modified including a new Appendix C: Suggested evaluation of the cardiovascular system for divers. The revised evaluation of the cardiovascular system for divers covers the following topics: 1. Background information on the relevance of cardiovascular risk and diving; 2. Defining which divers with cardiovascular problems should not dive, or whom require treatment interventions before further review; 3. Recommended screening procedures (flowchart) for divers aged 45 and over; 4. Assessment of divers with known or symptomatic cardiovascular disease, including guidance on assessing divers with specific diagnoses such as hypertension, atrial fibrillation, cardiac pacemaker, immersion pulmonary oedema, takotsubo cardiomyopathy, hypertrophic cardiomyopathy and persistent (patent) foramen ovale; 5. Additional cardiovascular health questions included in the SPUMS guidelines for medical risk assessment in recreational diving; 6. Updated general cardiovascular medical risk assessment advice; 7. Referencing of relevant literature. The essential elements of this guideline are presented in this paper.

Dive Medicine: Current Perspectives and Future Directions

As SCUBA diving continues to rapidly grow in the United States and worldwide, physicians should have a fundamental working knowledge to provide care for an injured diver. SCUBA divers are faced with many hazards at depths that are normally well compensated for at sea level. Pressure gradients, changes in the partial pressure of inhaled gases and gas solubility can have disastrous effects to the diver if not managed properly. Many safety measures in SCUBA diving are governed by the laws of physics, but some have come under scrutiny. This has prompted increased research concerning in water recompression and flying after diving. This article will give physicians an understanding of the dangers divers encounter and the current treatment recommendations. We will also explore some controversies in diving medicine.