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

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Objective To study the effect of percutaneous patent foramen ovale (PFO) closure in divers with a history of decompression sickness (DCS). Study design (1) Retrospective study of patient records and (2) telephonic follow-up. Patients with unexplained decompression sickness, who were referred to a cardiologist with a focus on diving medicine between 2000 and 2017, were included in the study Results A total of 62 divers with DCS were included. In all cases transoesophageal echocardiography (TEE) was performed, showing 29 PFOs and 6 atrial septum defects (ASDs) in total n = 35 (56%). The highest prevalence was found in divers with cutaneous and vestibular DCS. At follow-up (mean follow-up duration 6.8 years), 21 PFOs/ASDs were closed using a percutaneous procedure. One diver was lost to follow-up. One diver quit diving. The remaining divers were able to resume unrestricted diving; there was no recurrence of major DCS. Of the divers with an open PFO or ASD, 14 were included of whom 7 are currently diving. All (except one diver with a small PFO) divers are using a conservative diving profile to reduce nitrogen load and the appearance of venous nitrogen bubbles. There was no recurrence of major DCS in this group. Conclusion Percutaneous PFO closure may be an effective and safe treatment for divers who have suffered a major DCS to return to unrestricted diving. Alternatively, conservative treatment seems safe when divers refrain from unrestricted diving and use a conservative technique in order to reduce nitrogen load.
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ORIGINAL ARTICLE
https://doi.org/10.1007/s12471-018-1153-x
Neth Heart J
Persistent foramen ovale closure in divers with a history of
decompression sickness
R. Koopsen1·P.R.Stella
2·K.M.Thijs
3·R.Rienks
2,4
© The Author(s) 2018
Abstract
Objective To study the effect of percutaneous patent foramen ovale (PFO) closure in divers with a history of decompression
sickness (DCS).
Study design (1) Retrospective study of patient records and (2) telephonic follow-up. Patients with unexplained decom-
pression sickness, who were referred to a cardiologist with a focus on diving medicine between 2000 and 2017, were
included in the study
Results A total of 62 divers with DCS were included. In all cases transoesophageal echocardiography (TEE) was per-
formed, showing 29 PFOs and 6 atrial septum defects (ASDs) in total n= 35 (56%). The highest prevalence was found in
divers with cutaneous and vestibular DCS. At follow-up (mean follow-up duration 6.8 years), 21 PFOs/ASDs were closed
using a percutaneous procedure. One diver was lost to follow-up. One diver quit diving. The remaining divers were able
to resume unrestricted diving; there was no recurrence of major DCS. Of the divers with an open PFO or ASD, 14 were
included of whom 7 are currently diving. All (except one diver with a small PFO) divers are using a conservative diving
profile to reduce nitrogen load and the appearance of venous nitrogen bubbles. There was no recurrence of major DCS in
this group.
Conclusion Percutaneous PFO closure may be an effective and safe treatment for divers who have suffered a major DCS to
return to unrestricted diving. Alternatively, conservative treatment seems safe when divers refrain from unrestricted diving
and use a conservative technique in order to reduce nitrogen load.
Keywords Patent foramen ovale · Decompression sickness · Diving
What’s new?
Vestibular DCS and cutis marmorata are frequently asso-
ciated with PFO.
PFO closure in divers with a history of DCS is a safe
and effective treatment for divers to return to unrestricted
diving.
If the diver refrains from PFO closure, a restrictive diving
profile seems safe and could be recommended.
R. Koopsen
r.koopsen@students.uu.nl
1Utrecht University, Utrecht, The Netherlands
2Department of Cardiology, University Medical Center,
Utrecht, The Netherlands
3Department of Sports Medicine, University Medical Center,
Utrecht, The Netherlands
4Central Military Hospital, Utrecht, The Netherlands
Introduction
Decompression illness (DCI) is a major medical problem
among scuba divers. As a diver descends and breathes air
under increased pressure, the tissues become loaded with
increased quantities of nitrogen. During ascent, but espe-
cially after the dive, this nitrogen is released into the blood
which can lead to bubble formation. The volume and loca-
tion of these bubbles determine whether symptoms occur
[1].
Decompression illness (DCI) comprises both arterial gas
embolism (AGE) and decompression sickness (DCS). AGE
usually occurs directly after surfacing and is caused by lung
problems (bullae or blebs) or a provocative diving profile
(rapid ascent with breath holding), causing overstretching
and tearing of the alveoli leading to air bubbles in the pul-
monary veins and subsequently into the arterial system (pul-
monary barotrauma).
DCS is caused by nitrogen bubbles. The nitrogen that has
been stored in the tissues during the dive disappears by dif-
Neth Heart J
fusion into the venous system. It is subsequently transported
to the lungs and exhaled. When the pressure decreases dur-
ing ascent, and especially after the dive, there may be bub-
ble formation in the tissue and in the veins. This occurs
when the nitrogen concentration exceeds the capacity of the
tissue and the venous system to remove the nitrogen. Local
bubble formation usually results in ‘type 1’ DCS whereas
venous bubble formation may result in ‘type 2’ DCS in
the presence of a right-to-left shunt. DCS usually develops
from about 20 min after surfacing.
‘Minor decompression illness’, or type 1 manifests as
musculoskeletal and cutaneous symptoms, such as pain
around the joint, skin rash and pruritus. ‘Major decompres-
sion illness’, or type 2 causes neurological, vestibular or
pulmonary symptoms [2].
Recently it was hypothesised that cutis marmorata,
which had previously been classified under type 1 DCS,
may be better classified under type 2 DCS, because of its
postulated neurogenic origin [3,4].
When DCI occurs when diving safety limits have been
violated it is considered to be ‘deserved’ DCI. However,
in half of the cases, DCI is ‘undeserved’ i.e. it occurs de-
spite compliance with the standardised decompression pro-
cedures. In cases of undeserved DCI, it is warranted to
look for a right-to-left shunt facilitating the transition of
nitrogen bubbles from the venous to the arterial circulation.
The most frequent cause of a right-to-left shunt is patent
foramen ovale (PFO). Although PFO is present in a quar-
ter to one-third of the general population, the risk of having
a DCI event is low and has been reported to be 2.5 in 10,000
divers. However it is five times higher in divers with a PFO
than in those without a PFO [5]. It is suggested that a small
PFO may not contribute to DCI, and a large PFO (diameter
>10 mm) may [6].
There are few data on the recurrence of decompression
sickness after the first event. In a group of 50 recreational
divers with neurological DCS, neurological DCS reoccurred
in 48% of the divers [7]. A prospective study in 104 scuba
divers (divided into 3 groups: no PFO, closed PFO and
open PFO) performing 18,394 dives over a period of 5 years
showed major DCI events mainly in the open PFO group,
suggesting a protective effect of PFO closure [8]. Another
study comparing divers with a PFO to divers treated with
catheter-based PFO closure showed complete elimination
of arterial bubbles after simulated dives [9].
Percutaneous closure of PFO has been used to reduce the
risk of DCI and has been shown to be safe and allow most
patients to return to unrestricted diving [10]. However, the
effect of closure on the rate of recurrence of DCI has not
been properly established. Our study observed the clinical
course of patients who had suffered a DCS, whether or not
after PFO closure.
Methods
This retrospective study was conducted at the University
Medical Center Utrecht. Patients with unexplained decom-
pression sickness, who were referred to a cardiologist with
a focus on diving medicine between 2000 and 2017, were
included in the study.
Data were retrieved from our electronic patient file. At
time of presentation, a detailed description of the diving
accident, timetable of occurrence of symptoms, treatment,
medical history and diving experience were obtained.
A DCS event was classified into different types of DCS:
musculoskeletal, skin bends, cutis marmorata, neurological
or vestibular.
Analysis at presentation included transoesophageal
echocardiography (TEE) with contrast and using the Val-
salva manoeuver for detecting right-to-left shunts, com-
puted tomography (CT) scan of the thorax and magnetic
resonance imaging (MRI) of the cerebrum.
A telephone questionnaire was used to gather informa-
tion about current diving activities. The divers were asked if
they were currently diving, if they had changed their diving
profile focusing on reduction of venous bubble load (use of
nitrox, restrictions on the depth of the dive, strict adherence
to decompression tables, no repetitive dives during a single
day and reduced rate of ascent) and if they had experienced
any diving-related problems such as DCS.
All PFO and atrial septal defects (ASD) closures were
performed using a standardised procedure as has been de-
scribed previously [11]. The PFO/ASD was closed under
local anaesthesia with intracardiac echocardiography (ICE)
guidance. In almost 90% of the cases a Figulla Flex PFO oc-
cluder was used (Occlutech) while the remaining 10% was
closed with an Amplatzer PFO occluder (ABBOTT). Post-
procedural thrombosis prophylaxis consisted of 6 months of
treatment with carbasalate calcium and 3 months of clopi-
dogrel. The advice was given to resume diving six months
after the procedure. At that time, the antiplatelet therapy
was discontinued because it is presumed that full endothe-
lialisation of the atrial wall has taken place [12].
Results
A total of 77 divers were referred to our hospital between
2000 and 2017 for cardiac analyses after a decompression
illness. Ten divers were excluded because decompression
illness was unlikely, one diver did not attend the exam-
ination. Another four divers were excluded because they
suffered from arterial gas embolism (AGE); 62 divers were
analysed with a history of decompression sickness.
In all cases, a transoesophageal echocardiography (TEE)
was performed, showing 29 PFOs and 6 haemodynamically
Neth Heart J
Tab le 1 Patient characteristics and analysis of type of DCS and prevalence of PFO
DCS Total
(n= 62)
PFO/ASD absent
(n= 27)
PFO/ASD present
(n= 35)
PFO/ASD closed
(n= 21)
PFO/ASD not
closed
(n= 14)
Male (%) 58.1 66.7 51.4 57.1 42.9
Mean age (years, range) 38.3 (20–61) 33.0 (20–55) 42.3 (25–61) 44.7 (25–61) 38.8 (30–61)
Typ e 1
Musculoskeletal 2 2 0 0 0
Skin bends 8 3 5 2 3
Typ e 2
Cutis marmorata 15 3 12 10 2
Neurological 26 17 9 3 6
Vestibular 11 2 9 6 3
ASD atrial septum defect, DCS decompression sickness, PFO patent foramen ovale
Fig. 1 Clinical follow-up
0
2
4
6
8
10
12
14
16
PFO/ASD absent
(N=27)
PFO/ASD not closed
(N=14)
PFO/ASD closed
(N=21)
Number of divers
Quit diving
Connued unrestricted diving
Connued restricted diving
Not allowed to dive yet
Minor DCS
Major DCS
not significant ASDs (n= 35 in total: 56%). No other right-
to-left shunts were found. The echocardiographic data are
presented in Tab. 1. We found a high prevalence of PFO
in the subgroup of divers with cutis marmorata (80%) and
vestibular DCS (82%). A PFO or ASD was only found in
35% of divers with neurological DCS.
The mean follow-up duration was 6.8 years (range
0.5–11.6 years). At follow-up, there were 14 divers with an
open PFO. Two of them were lost to follow-up. Four divers
chose to change their diving profile instead of PFO clo-
sure in order to reduce venous bubble load, and continued
diving. In two divers, closure of the PFO was not offered
because they had a history of skin bends, which was later
not considered to be an indication for percutaneous clo-
sure of an PFO. They continued restricted diving as well.
Three divers had other strict contraindications for diving
such as pulmonary bullae or pulmonary emphysema, which
made closing of the PFO irrelevant. One diver decided
to quit diving. One diver, with a minor PFO, continued
unrestricted diving. No recurrence of major DCS occurred.
Two divers experienced minor DCS during follow-up, one
with an unrestricted diving profile and one with restrictions
(Fig. 1).
In 21 divers the PFO or ASD was closed, one of whom
was lost to follow-up. Out of 20 divers, 17 continued div-
ing. Three had changed their diving profile additionally.
In two divers the PFO had been closed recently and they
were not yet allowed to dive. None of the divers experi-
enced recurrence of major DCS after the PFO was closed.
However, one diver experienced minor DCS/skin bends af-
ter PFO closure. Four divers spontaneously reported that,
when looking retrospectively, they might have experienced
multiple minor DCS in the past as well, before the PFO was
closed, which they had not recognised as such at the time.
One diver was no longer diving despite successful closure
of a PFO.
In one diver, paroxysmal atrial fibrillation occurred di-
rectly after closure of the PFO. A TTE with contrast, at
4-month follow-up, did not show any residual shunts among
the treated divers.
Neth Heart J
Fig. 2 Clinical decision making
Patient with
unexplained DCS
TTE shows no ASD
or PFO
TTE shows
haemodynamically
insignificant ASD or
PFO
Patient has no
problem with a
conservative
diving profile or
refrains from
ASD/PFO closure
Patient wishes to
continue
unrestricted
diving, agrees to
ASD/PFO closure
and has no
contraindications
against ASD/PFO
closure
Patient
continues
unrestricted
diving
Conservative
diving profile ASD/PFO
closure
Most divers with no cardiac pathology continued diving
without adjusting their diving profile (55%). In one subject,
recurrence of DCS occurred.
Discussion
This study attempted to establish the efficacy of PFO clo-
sure in patients with a history of DCS. In 20 divers with
a closed PFO, major DCS did not reoccur. All divers were
able to go back to unrestricted diving, although three divers
preferred to continue their diving activities more conserva-
tively. As the present study is descriptive and there is no
comparison group, the efficacy of PFO closure could not
be statistically quantified.
Conservative or restricted diving is generally based on
common-sense advice with regard to decompression safety.
Clear guidelines on restricted diving are lacking. Kling-
mann et al. observed a significant reduction of DCS af-
ter providing the following recommendations: use of nitrox
with decompression times calculated on air tables, no deep
dives ( >25 meters), no repetitive dives, min imisation of Val-
salva manoeuvres, no decompression dives and a 5-minute
safety stop at 3 msw [13].
Currently, the most frequent indication for PFO closure
is the increased risk of cryptogenic stroke, migraine and
vascular headache. The safety and efficacy of percutaneous
closure of PFO has been the subject of several studies.
Three multicentre studies comparing PFO closure to an-
tiplatelet therapy have shown the safety of PFO closure.
These trials found a significantly higher rate of (transient)
atrial fibrillation in the PFO group than in the comparison
group but no differences in serious adverse events [1416].
In our population, paroxysmal atrial fibrillation occurred in
one patient.
Since the majority of the group with an open PFO either
quit diving or changed to a more conservative diving profile,
it is not possible to compare the group with an open PFO
to the group with a closed PFO with respect to unrestricted
diving. However, in this group no recurrence of major DCS
was seen either.
In the group without PFO or ASD, major DCS reoc-
curred in one subject, which was later attributed to the
complications of sinusitis.
Billinger et al. found no recurrences of major DCI during
long-term follow-up in 26 divers (1,208 dives) who under-
went percutaneous closure of their PFO, which is consistent
with our findings. Yet, a case report has been published
which describes a diver who redeveloped cutaneous DCI
after treatment with a PFO occluder four years earlier [17].
The overall prevalence of right-to-left shunts in this pop-
ulation of divers with undeserved DCS is 56%. This is
higher than expected in the general population (approxi-
mately 27%) [5]. We found a high prevalence of right-to-
Neth Heart J
left shunts in both divers with cutis marmorata (80%) and
in divers with vestibular DCS (82%).
In the present patient group, initially skin bends and cutis
marmorata were considered equally as ‘cutaneous DCS’,
and thus ‘minor DCS’. There is increasing interest in the
aetiology of cutaneous DCS. Kemper et al. proposed that
cutis marmorata may be cerebrally mediated, as they found
an association between cutis marmorata and cardiac right-
to-left shunts [4]. This is consistent with our high preva-
lence of shunts in this population. Also, this new insight
can explain why originally no clear policy was followed
regarding PFO closure in patients with a history of skin
bends. At first, the PFOs of two divers were closed, later
two divers were advised to use a more conservative diving
profile.
In comparison to cutis marmorata and vestibular DCS,
we found a relatively low prevalence of right-to-left shunts
in patients with a neurological DCS (38%). A likely expla-
nation may be that patients with unspecific symptoms such
as fatigue, weakness, nausea, headache and disorientation
were all classified as neurological DCS. However, we did
not find a high prevalence of PFO/ASD in the patients with
more specific neurological symptoms. In our population, no
cases of paralysis or paraplegia occurred.
Conclusion
For divers who had suffered a major DCS, percutaneous
PFO closure may be an effective and safe treatment to re-
turn to unrestricted diving. Alternatively, a restrictive diving
profile seems safe and could be recommended for divers
who refrain from PFO closure (Fig. 2).
Conflict of interest R. Koopsen, P.R. Stella, K.M. Thijs and R. Rienks
declare that they have no competing interests.
Open Access This article is distributed under the terms of the
Creative Commons Attribution 4.0 International License (http://
creativecommons.org/licenses/by/4.0/), which permits unrestricted
use, distribution, and reproduction in any medium, provided you give
appropriate credit to the original author(s) and the source, provide a
link to the Creative Commons license, and indicate if changes were
made.
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... In other studies it was also reported that even though the PFO was closed, a significant number of divers adopted a more conservative diving attitude (Koopsen et al., 2018;Anderson et al., 2019;Vanden Eede et al., 2019). A recent report (Anderson et al., 2019) described a better reduction of DCS incidence after PFO closure compared to "conservative diving, " but major methodological flaws have been pointed out by an accompanying editorial (Wilmshurst, 2019). ...
Article
Full-text available
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.
... So-called minor DCS (i.e., DCS type I) is caused by the local formation of bubbles and presents with skin and/or musculoskeletal symptoms, such as itching, skin rash, and joint pain. Major DCS, or type II, is due to the formation of venous bubbles that induce neurological, vestibular (dizziness /vertigo), or pulmonary symptoms in the presence of a right-to-left shunt caused by PFO [44]. ...
Article
Full-text available
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.
... 19 To our knowledge there are fi ve studies of DCS outcomes after PFO closure. In two studies, 14,24 no episodes of major DCS were reported after PFO closure in 11 and 20 divers respectively. Another showed a decreased DCS incidence after PFO/ASD closure. ...
Article
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.
Article
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.
Article
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.
Article
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.
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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.
Article
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.
Article
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.
Article
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.
Article
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Background Trials of patent foramen ovale (PFO) closure to prevent recurrent stroke have been inconclusive. We investigated whether patients with cryptogenic stroke and echocardiographic features representing risk of stroke would benefit from PFO closure or anticoagulation, as compared with antiplatelet therapy. Methods In a multicenter, randomized, open-label trial, we assigned, in a 1:1:1 ratio, patients 16 to 60 years of age who had had a recent stroke attributed to PFO, with an associated atrial septal aneurysm or large interatrial shunt, to transcatheter PFO closure plus long-term antiplatelet therapy (PFO closure group), antiplatelet therapy alone (antiplatelet-only group), or oral anticoagulation (anticoagulation group) (randomization group 1). Patients with contraindications to anticoagulants or to PFO closure were randomly assigned to the alternative noncontraindicated treatment or to antiplatelet therapy (randomization groups 2 and 3). The primary outcome was occurrence of stroke. The comparison of PFO closure plus antiplatelet therapy with antiplatelet therapy alone was performed with combined data from randomization groups 1 and 2, and the comparison of oral anticoagulation with antiplatelet therapy alone was performed with combined data from randomization groups 1 and 3. Results A total of 663 patients underwent randomization and were followed for a mean (±SD) of 5.3±2.0 years. In the analysis of randomization groups 1 and 2, no stroke occurred among the 238 patients in the PFO closure group, whereas stroke occurred in 14 of the 235 patients in the antiplatelet-only group (hazard ratio, 0.03; 95% confidence interval, 0 to 0.26; P<0.001). Procedural complications from PFO closure occurred in 14 patients (5.9%). The rate of atrial fibrillation was higher in the PFO closure group than in the antiplatelet-only group (4.6% vs. 0.9%, P=0.02). The number of serious adverse events did not differ significantly between the treatment groups (P=0.56). In the analysis of randomization groups 1 and 3, stroke occurred in 3 of 187 patients assigned to oral anticoagulants and in 7 of 174 patients assigned to antiplatelet therapy alone. Conclusions Among patients who had had a recent cryptogenic stroke attributed to PFO with an associated atrial septal aneurysm or large interatrial shunt, the rate of stroke recurrence was lower among those assigned to PFO closure combined with antiplatelet therapy than among those assigned to antiplatelet therapy alone. PFO closure was associated with an increased risk of atrial fibrillation. (Funded by the French Ministry of Health; CLOSE ClinicalTrials.gov number, NCT00562289.)
Article
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Objectives This study sought to evaluate the effect of catheter-based patent foramen ovale (PFO) closure on the occurrence of arterial bubbles after simulated dives. Background PFO is a risk factor of decompression sickness in divers due to paradoxical embolization of bubbles. To date, the effectiveness of catheter-based PFO closure in the reduction of arterial bubbles has not been demonstrated. Methods A total of 47 divers (age 35.4 ± 8.6 years, 81% men) with a PFO (PFO group) or treated with a catheter-based PFO closure (closure group) were enrolled in this case-controlled observational trial. All divers were examined after a simulated dive in a hyperbaric chamber: 34 divers (19 in the PFO group, 15 in the closure group) performed a dive to 18 m for 80 min, and 13 divers (8 in the PFO group, 5 in the closure group) performed a dive to 50 m for 20 min. Within 60 min after surfacing, the presence of venous and arterial bubbles was assessed by transthoracic echocardiography and transcranial color-coded sonography, respectively. Results After the 18-m dive, venous bubbles were detected in 74% of divers in the PFO group versus 80% in the closure group (p = 1.0), and arterial bubbles were detected in 32% versus 0%, respectively (p = 0.02). After the 50-m dive, venous bubbles were detected in 88% versus 100%, respectively (p = 1.0), and arterial bubbles were detected in 88% versus 0%, respectively (p < 0.01). Conclusions No difference was observed in the occurrence of venous bubbles between the PFO and closure groups, but the catheter-based PFO closure led to complete elimination of arterial bubbles after simulated dives. (Nitrogen Bubble Detection After Simulated Dives in Divers With PFO and After PFO Closure; NCT01854281)
Article
Among patients with a PFO who had had a cryptogenic stroke, the risk of subsequent ischemic stroke was lower among those assigned to PFO closure combined with antiplatelet therapy than among those assigned to antiplatelet therapy alone; however, PFO closure was associated with higher rates of device complications and atrial fibrillation.
Article
BAGROUND: The efficacy of closure of a patent foramen ovale (PFO) in the prevention of recurrent stroke after cryptogenic stroke is uncertain. We investigated the effect of PFO closure combined with antiplatelet therapy versus antiplatelet therapy alone on the risks of recurrent stroke and new brain infarctions. METHODS: In this multinational trial involving patients with a PFO who had had a cryptogenic stroke, we randomly assigned patients, in a 2:1 ratio, to undergo PFO closure plus antiplatelet therapy (PFO closure group) or to receive antiplatelet therapy alone (antiplatelet-only group). Imaging of the brain was performed at the baseline screening and at 24 months. The coprimary end points were freedom from clinical evidence of ischemic stroke (reported here as the percentage of patients who had a recurrence of stroke) through at least 24 months after randomization and the 24-month incidence of new brain infarction, which was a composite of clinical ischemic stroke or silent brain infarction detected on imaging. RESULTS: We enrolled 664 patients (mean age, 45.2 years), of whom 81% had moderate or large interatrial shunts. During a median follow-up of 3.2 years, clinical ischemic stroke occurred in 6 of 441 patients (1.4%) in the PFO closure group and in 12 of 223 patients (5.4%) in the antiplatelet-only group (hazard ratio, 0.23; 95% confidence interval [CI], 0.09 to 0.62; P=0.002). The incidence of new brain infarctions was significantly lower in the PFO closure group than in the antiplatelet-only group (22 patients [5.7%] vs. 20 patients [11.3%]; relative risk, 0.51; 95% CI, 0.29 to 0.91; P=0.04), but the incidence of silent brain infarction did not differ significantly between the study groups (P=0.97). Serious adverse events occurred in 23.1% of the patients in the PFO closure group and in 27.8% of the patients in the antiplatelet-only group (P=0.22). Serious device-related adverse events occurred in 6 patients (1.4%) in the PFO closure group, and atrial fibrillation occurred in 29 patients (6.6%) after PFO closure. CONCLUSIONS: Among patients with a PFO who had had a cryptogenic stroke, the risk of subsequent ischemic stroke was lower among those assigned to PFO closure combined with antiplatelet therapy than among those assigned to antiplatelet therapy alone; however, PFO closure was associated with higher rates of device complications and atrial fibrillation.
Article
Background Whether closure of a patent foramen ovale reduces the risk of recurrence of ischemic stroke in patients who have had a cryptogenic ischemic stroke is unknown. Methods In a multicenter, randomized, open-label trial, with blinded adjudication of end-point events, we randomly assigned patients 18 to 60 years of age who had a patent foramen ovale (PFO) and had had a cryptogenic ischemic stroke to undergo closure of the PFO (PFO closure group) or to receive medical therapy alone (aspirin, warfarin, clopidogrel, or aspirin combined with extended-release dipyridamole; medical-therapy group). The primary efficacy end point was a composite of recurrent nonfatal ischemic stroke, fatal ischemic stroke, or early death after randomization. The results of the analysis of the primary outcome from the original trial period have been reported previously; the current analysis of data from the extended follow-up period was considered to be exploratory. Results We enrolled 980 patients (mean age, 45.9 years) at 69 sites. Patients were followed for a median of 5.9 years. Treatment exposure in the two groups was unequal (3141 patient-years in the PFO closure group vs. 2669 patient-years in the medical-therapy group), owing to a higher dropout rate in the medical-therapy group. In the intention-to-treat population, recurrent ischemic stroke occurred in 18 patients in the PFO closure group and in 28 patients in the medical-therapy group, resulting in rates of 0.58 events per 100 patient-years and 1.07 events per 100 patient-years, respectively (hazard ratio with PFO closure vs. medical therapy, 0.55; 95% confidence interval [CI], 0.31 to 0.999; P=0.046 by the log-rank test). Recurrent ischemic stroke of undetermined cause occurred in 10 patients in the PFO closure group and in 23 patients in the medical-therapy group (hazard ratio, 0.38; 95% CI, 0.18 to 0.79; P=0.007). Venous thromboembolism (which comprised events of pulmonary embolism and deep-vein thrombosis) was more common in the PFO closure group than in the medical-therapy group. Conclusions Among adults who had had a cryptogenic ischemic stroke, closure of a PFO was associated with a lower rate of recurrent ischemic strokes than medical therapy alone during extended follow-up. (Funded by St. Jude Medical; RESPECT ClinicalTrials.gov number, NCT00465270.)
Article
It is well known that patency of the foramen ovale (PFO) is a risk factor for decompression illness (DCI) in scuba divers, even if they adhere to the currently accepted and used decompression tables (termed "an undeserved hit"). The correction of the PFO through percutaneous closure after DCI is an ongoing discussion. We describe a case of a diver who redeveloped a cutaneous DCI due to a recurrent PFO after initial treatment with an occluder device four years earlier.
Article
Decompression illness (DCI) is associated with a right-to-left shunt, such as persistent foramen ovale (PFO), atrial septal defect (ASD) and pulmonary arteriovenous malformations. About one-quarter of the population have a PFO, but considerably less than one-quarter of divers suffer DCI. Our aim was to determine whether shunt-related DCI occurs mainly or entirely in divers with the largest diameter atrial defects. Case control comparison of diameters of atrial defects (PFO and ASD) in 200 consecutive divers who had transcatheter closure of an atrial defect following shunt-related DCI and in an historic group of 263 individuals in whom PFO diameter was measured at post-mortem examination. In the divers who had experienced DCI, the median atrial defect diameter was 10 mm and the mean (standard deviation) was 9.9 (3.6) mm. Among those in the general population who had a PFO, the median diameter was 5 mm and mean was 4.9 (2.6) mm. The difference between the two groups was highly significant (P < 0.0001). Of divers with shunt-related DCI, 101 (50.5%) had an atrial defect 10 mm diameter or larger, but only 1.3% of the general population studied had a PFO that was 10 mm diameter of larger. The risk of a diver suffering DCI is related to the size of the atrial defect rather than just the presence of a defect.
Article
Right-to-left shunt across a persistent foramen ovale (PFO) has been associated with cutaneous, neurological and vestibular decompression illness (DCI). Percutaneous closure of a PFO has been used to reduce the risk of DCI. There are no randomised controlled trial data to support PFO closure for the prevention of decompression illness (DCI), so the need for audit data on the safety and efficacy of this technique has been recognised by the National Institute of Health and Clinical Excellence in the UK. Retrospective audit of all transcatheter PFO closures to reduce the risk of DCI performed by a single cardiologist with an interest in diving medicine. A total of 105 eligible divers undergoing 107 procedures was identified. There was a low rate of procedural complications; a rate lower than a recent randomised trial of PFO closure for stroke. Atrial fibrillation required treatment in two patients. One patient with a previously repaired mitral valve had a stroke that was thought to be unrelated to the PFO closure. Sixteen divers had minor post-procedure symptoms not requiring any treatment. Two divers required a second procedure because of residual shunt; both subsequently returned to unrestricted diving. Eighty-one of 95 divers in whom follow-up bubble contrast echocardiography was available returned to unrestricted diving. The PFO closure procedure appeared to be safe and was associated with the majority of divers being able to successfully return to unrestricted diving.
Article
Cutaneous decompression sickness (DCS) is often considered to be a mild entity that may be explained by either vascular occlusion of skin vessels by bubbles entering the arterial circulation through a right-to-left shunt or bubble formation due to saturated subcutaneous tissue during decompression. We propose an alternative hypothesis. The case is presented of a 30-year-old female diver with skin DCS on three separate occasions following relatively low decompression stress dives. Also presented are the findings of cutaneous appearances in previously reported studies on cerebral arterial air embolism in pigs. There was a close similarity in appearance between the skin lesions in this woman (and in other divers) and those in the pigs, suggesting a common pathway. From this, we hypothesize that the cutaneous lesions are cerebrally mediated. Therefore, cutaneous DCS might be a more serious event that should be treated accordingly. This hypothesis may be supported by the fact that cutis marmorata is also found in other fields of medicine in a non-diving context, where the rash is referred to as livedo reticularis or livedo racemosa. These are associated with a wide number of conditions but of particular interest is Sneddon's syndrome, which describes the association of livedo racemosa with cerebrovascular events or vascular brain abnormalities. Finally, there is a need for further research on the immunocytochemical pathway of cutaneous DCS.