This Was the Goal of Art During the Realistic Period of American Literature
Interv Cardiol. 2020 Apr; 15: e15.
Patent Foramen Ovale Closure: Land of the Art
Joel P Giblett
ane. Liverpool Heart for Cardiovascular Science, Liverpool Heart and Chest Hospital, Liverpool, UK
Lynne G Williams
2. Department of Cardiology, Imperial Papworth Hospital NHS Foundation Trust, Cambridge, United kingdom
Stephen Kyranis
2. Section of Cardiology, Purple Papworth Hospital NHS Foundation Trust, Cambridge, UK
Leonard Chiliad Shapiro
two. Section of Cardiology, Imperial Papworth Hospital NHS Foundation Trust, Cambridge, UK
Patrick A Calvert
2. Section of Cardiology, Regal Papworth Hospital NHS Foundation Trust, Cambridge, United kingdom
Received 2019 Nov 24; Accepted 2020 Sep 22.
Abstract
Patent foramen ovale (PFO) is a common abnormality affecting between 20% and 34% of the developed population. For most people, information technology is a benign finding; however, in some people, the PFO tin open widely to enable paradoxical embolus to transit from the venous to arterial circulation, which is associated with stroke and systemic embolisation. Percutaneous closure of the PFO in patients with cryptogenic stroke has been undertaken for a number of years, and a number of purpose-specific septal occluders have been marketed. Recent randomised control trials have demonstrated that closure of PFO in patients with cryptogenic stroke is associated with reduced rates of recurrent stroke. After a brief overview of the anatomy of a PFO, this article considers the evidence for PFO closure in cryptogenic stroke. The article besides addresses other potential indications for closure, including systemic arterial embolisation, decompression sickness, platypnoea–orthodeoxia syndrome and migraine with aura. The article lays out the pre-procedural investigations and grooming for the process. Finally, the article gives an overview of the procedure itself, including give-and-take of closure devices.
Keywords: Stroke, patent foramen ovale, patent foramen ovale closure, migraine, platypnoea–orthodeoxia syndrome, decompression illness, cryptogenic stroke
Patent foramen ovale (PFO) is common and occurs in 20–34% of the population.[1] In most infants, the foramen ovale closes soon after birth, with a reduction in pulmonary vascular resistance raising the left atrial pressure above that of the correct atrium during the first few breaths, closing the septum. In a significant proportion of individuals, the primum and secundum atrial septa practice not fuse, and the foramen ovale remains incompletely closed. There is a residual, but transitory, communication between the right and left atria, peculiarly likely to open during actions that cause sudden rises and falls in intrathoracic pressure level, such as sneezing, coughing or straining. The pressure changes that transiently open a PFO tin often exist produced past asking patients with a PFO to perform and and so release a Valsalva manoeuvre.
In almost adults, a PFO volition appear but every bit a chance finding during cardiac investigation, or more likely remain undetected. Some PFOs may open widely, providing a conduit for thrombus, air or vasoactive peptides to travel from the venous to arterial circulation – causing a paradoxical embolus. This transfer is associated with several clinical phenomena, including cryptogenic stroke, systemic embolus, migraine with aureola and decompression sickness in divers. Percutaneous PFO closure provides a practical and elegant solution to the problem of PFO in carefully selected individuals. This review evaluates the evidence for PFO closure, discusses which patients should be considered for this treatment and reviews how the procedure should exist undertaken.
The Beefcake of a Patent Foramen Ovale
As the heart develops in the foetus, the primum and secundum septa grow and overlap. At nascency, the PFO should close. In patients with a PFO, the atrial septal growth is normal; however, the communication betwixt the right and left atria (PFO) fails to close postpartum ( Effigy 1 ). This miracle is singled-out from a hole in either septum, which would constitute an atrial septal defect (ASD) – a split up entity with different functional consequences and different indications for closure. Table 1 compares PFO and ASD.
Echocardiographic Cess of a Patent Foramen Ovale
A and B: A transthoracic echo bubble written report. A: An apical four chamber view. Agitated saline after Four injection is seen to fill the right ventricular cavity (white arrow). B: Bubbles are seen in the left atrium (LA) and ventricle within three cardiac cycles (blue pointer). C: A 2D transoesophageal echo image (xc°) of a patent foramen ovale (PFO; orangish arrow) with shunting evident on the color flow Doppler. D: The same PFO is seen in 3D, viewed from the left atrium. The points of attachment of the septum primum tissue are shown past the white asterisks. The PFO opening into the left atrium is seen betwixt these two points. The septum secundum tissue is behind, and this overlap of tissue extends to the roof of the fossa ovalis, demarcated by the white dotted line. The PFO tunnel therefore extends from the height of the fossa ovalis to the PFO opening. LA = left atrium; MV = mitral valve; RA = right atrium.
Tabular array 1:
Comparison of Patent Foramen Ovale and Atrial Septal Defects
| Patent Foramen Ovale | Atrial Septal Defect | |
|---|---|---|
| Beefcake | Fusion of primum and secundum atrial septa does non occur as an infant leading to flap valve opening | Congenital failure of overlap of the atrial septa leads to a hole in atrial septum) |
| Shunt | Right to left shunt occurs when right atrial pressure exceeds left atrial pressure (usually transient subsequently rapid rise and fall in thoracic pressure) | Continuous left-to-correct (normally) shunting |
| Epidemiology | 20–34% of developed population[1] | 1.6/1,000 live births[48] |
| Consequences | In most cases there is no clinical result and the defect remains undetected May permit paradoxical embolus | Continuous left-to-right shunt may cause volume loading of right centre, which may reduce long-term survival if not corrected May increase pulmonary avenue force per unit area, reduce exercise tolerance and promote arrhythmia Tin also allow paradoxical embolus (indication for closure) |
Despite their differences, both PFOs and ASDs may allow the transit of a paradoxical embolism. The overlapping of the primum and secundum atrial septa in a PFO forms a flap valve that usually only opens when the correct atrial pressure exceeds the left atrial pressure. PFOs are functionally closed most of the time, as right atrial pressure level is usually less than the left atrial pressure. This pressure gradient can be reversed past manoeuvres that alter the intrathoracic pressure (e.g. sneezing, coughing or straining to defecate), allowing the PFO to open, and blood, thrombus or whatsoever other substance to pass across from the right to left atrium.
Indications for Patent Foramen Ovale Closure
Cryptogenic Stroke
Often, despite extensive investigation, a articulate cause cannot be plant for stroke. Causes that can exist identified include AF, atherosclerotic disease, carotid dissection and intracerebral pathology, such as haemorrhage or space-occupying lesions.[2,3] The cause of stroke remains unknown in upward to forty% of patients with a stroke diagnosis. These are designated every bit cryptogenic stroke. In the presence of a PFO, the presumed cause of stroke is paradoxical embolus. As the likely cause is known, the term 'cryptogenic' is a misclassification, but remains in utilise throughout the literature. An culling term is embolic stroke of undetermined source, which was start used in 2014. This still misclassifies stroke from paradoxical embolism, where the cause is known.[iv–vi]
Zahn first described paradoxical embolus in 1881.[7] Translocation of venous thrombus to the arterial circulation under the haemodynamic conditions in which a PFO is open leads to embolic stroke. Transit of thrombus occurs after a rapid rise and fall in right atrial pressure through the aforementioned mechanisms. The PFO channel briefly provides a advice between the atria. This machinery is supported by example studies showing thrombus across a PFO.[8–x] There is also an association between cryptogenic stroke and venous thrombosis in patients with a PFO.[11]
The earliest randomised trials of PFO closure (Evaluation of the STARFlex Closure System in Patients with a Stroke and/or Transient Ischemic Attack due to Presumed Paradoxical Embolism Through a Patent Foramen Ovale [CLOSURE I] and Percutaneous Closure of Patent Foramen Ovale Using the Amplatzer PFO Occluder With Medical Treatment in Patients With Cryptogenic Embolism [PC Trial]) did non demonstrate the superiority of closure compared with medical therapy.[12,13] Notwithstanding, the studies were confounded by limited ability, high crossover between groups, failure to randomise those patients whose strokes were likely to take been acquired by PFO and inconsistent employ of anticoagulants in the medical therapy group.[14] In addition, the STARFlex occluder used in CLOSURE I has been abandoned in Europe due to concerns around residual defects and left-sided thrombus germination.[xv] Some take concluded that numerical equipoise in these trials were enough to recommend a one-off mechanical vaccination paradoxical embolus rather than lifelong anticoagulation.[sixteen,17] Still, PFO closure was given a Class Three recommendation in the 2014 American Heart Association/American Stroke Association guidelines based on the results of these trials.
Nonetheless, further randomised trials learned lessons from earlier neutral studies and have demonstrated that PFO closure is superior to medical therapy for the prevention of recurrent stroke. Early on results from the Randomized Evaluation of Recurrent Stroke Comparing PFO Closure to Established Current Standard of Care Treatment (RESPECT) trial were neutral for PFO closure only extended follow upwardly of patients demonstrated a reduction in ischaemic stroke compared to medical therapy (HR 0.55; 95% CI [0.31–0.999]; p=0.046; number needed to treat [NNT] 45).[xviii,19] The Gore Septal Occluder Device for PFO Closure in Stroke Patients (REDUCE) clinical report demonstrated that PFO closure produced significant improvement in the clinical ischaemic stroke charge per unit (1.4 versus v.5%; p=0.002; NNT=25) compared with antiplatelet therapy lonely.[xx] The Device Closure Versus Medical Therapy for Cryptogenic Stroke Patients With High-Risk PFO (DEFENSE PFO) study showed that PFO closure reduced a blended endpoint of stroke, vascular death and thrombolysis in MI major bleeding at 2 years compared with medical therapy (0 versus 12.9%; p=0.013; NNT=8).[21] Finally, in the PFO Closure or Anticoagulants Versus Antiplatelet Therapy to Prevent Stroke Recurrence (Close) trial, no patient receiving PFO closure experienced an ischaemic stroke compared with 14 in the antiplatelet grouping (HR 0.03; 95% CI [0–0.26]; p<0.001; NNT=17).[22]
Meta-analyses of these trials ostend that PFO closure reduces the chance of ischaemic stroke in patients with a PFO and cryptogenic stroke.[23–25] Absolute take chances reduction is low (one.0 stroke per 100 patient-years), only this needs to be weighed against the prolonged menstruation that younger patients are likely to be at gamble. Patients with atrial septal aneurysm or large shunts may obtain greater benefit. In these trials, and in subsequent meta-analyses, AF occurred more than frequently in patients who underwent PFO closure than those receiving medical therapy lonely. Nonetheless, this finding did non seem to counteract the overall stroke reduction in this population. Randomised trials of PFO closure for the prevention of recurrent ischaemic stroke are shown in Table 2 .
Table 2:
Randomised Trials Comparison Patent Foramen Ovale Closure with Medical Therapy
| Study | Year | Device | n | Endpoints | Results | Comments |
|---|---|---|---|---|---|---|
| CLOSURE 1[12] | 2012 | STARFlex Septal Closure System | 909 | Composite of death (0–30 days), neurological death (≥31 days), stroke or TIA at two-year follow-upward | Not-meaning reduction in principal endpoint (HR 0.78; 95% CI [0.45–1.35] p=0.37) | Left atrial thrombus formation in closure group Inadequate closure at two years |
| PC Trial[13] | 2013 | Amplatzer PFO Occluder | 414 | Composite of death, stroke, TIA or peripheral embolism at 4,5 years | Non-significant reduction in primary endpoint (HR 0.63; 95% CI [0.24–1.62]; p=0.34) | Underpowered trial High book of crossover to PFO closure during follow-up |
| RESPECT[18,xix] | 2013 Long-term data published in 2017 | Amplatzer PFO Occluder | 980 | Composite of early decease, stroke or TIA | Non-significant reduction in primary endpoint at median follow-upwardly 2.1 years (Hour 0.49; 95% CI [0.22–1.eleven]; p=0.08) Long-term follow-up (median five.nine years) showed significant reduction with closure (HR 0.55; 95% CI [0.31–0.99]; p=0.046) | As treated analysis shows a benefit in favour of closure fifty-fifty at the early timepoint. |
| Shut[22] | 2017 | 11 approved devices (Amplatzer PFO Occluder >l%) | 663 | Fatal or not-fatal stroke | Significant reduction in stroke with occlusion compared with antiplatelet therapy only (60 minutes 0.03, 95% CI [ 0-0.26]; p<0.001) | 1:1:1 randomisation PFO closure versus antiplatelets versus anti-coagulation |
| Gore REDUCE[xx] | 2017 | Helex Septal Occluder or Cardioform Septal Occluder | 664 | Co-main endpoints of clinical stroke and incidence of new brain infarction | Significant reduction in clinical stroke at median follow-up 3.ii years (HR 0.23; 95% CI [0.09–0.62]; p=0.002) Significant reduction in new brain infarction (RR 0.51; 95% CI [0.29–0.91]; p=0.04) | 2:1 randomisation to PFO closure |
| DEFENSE PFO[21] | 2018 | Amplatzer PFO Occluder | 120 | Stroke, vascular expiry or Major haemorrhage at 2-year follow-upwardly | Meaning reduction in chief endpoint with PFO closure. No events in PFO closure arm versus 12.9% ii-year upshot rate in medication merely arm (p=0.013) |
PFO = patent foramen ovale; TIA = transient ischaemic assault.
Observational information suggest that post-closure AF may be transient, with a lower stroke risk than AF with other aetiology.[26] No trial or observational study has demonstrated a reduction in mortality with PFO closure, and indeed meta-assay of multiple trials has not establish a meaning effect either.[27–29] In that location may be a benefit, but it will remain hard to prove without large randomised trials with very long follow-up periods.
Patients enrolled in PFO closure trials were young, with few studies enrolling patients age >threescore years. Older patients may have an increased absolute take chances of paradoxical embolus, merely untangling this from other causes of stroke that also increment over time is challenging. Patients needed to have symptoms consistent with stroke and confirmation of ischaemia or infarction on cross-sectional encephalon imaging. Transoesophageal echocardiographic confirmation of the presence of a PFO was also required. Studies excluded patients with an alternative attributable cause for their stroke, and required enrolment no longer than six–nine months after the index stroke.
Ane of the major alternative explanations for embolic stroke is AF, and this was excluded in all patients. Studies take demonstrated that over the medium to long term, PFO closure is cost-effective in both the US and United kingdom of great britain and northern ireland healthcare systems.[30–32] Furthermore, longer-term observational studies accept shown very low stroke rates (<1%), even up to 12 years subsequently PFO closure.[33]
The strict criteria of these studies are important and should be respected in clinical practice. There is little or no evidence for handling of PFO exterior these criteria, and there is no symptomatic benefit to closure in patients with cryptogenic stroke. Patients who see trial criteria for closure should exist considered for this handling in preference to medical therapy. Patient choice is best decided in a multidisciplinary team coming together including neurology/stroke physicians, and implanting and imaging cardiologists.
Systemic Embolisation
Paradoxical emboli are likely to nowadays with ischaemic stroke, as the brain is exquisitely sensitive to ischaemia and also receives a large proportion of cardiac output. However, systemic embolisation to the limbs, gut and downwardly the coronary arteries have been described.[10,34–36] No randomised trial evidence exists to evidence that closure of PFO in the case of otherwise unexplained systemic embolisation is protective. However, closure would seem to be a reasonable strategy in select cases. For instance, closure of PFO would be indicated in a young patient presenting with acute MI of embolic source, with otherwise unremarkable coronary arteries and an absenteeism of hazard factors for atherosclerosis or atrial fibrillation. The indications are like to those for cryptogenic stroke. Importantly, care must be taken to exclude alternative causes, and this may require intravascular imaging, such every bit optical coherence tomography, to exclude plaque rupture in the coronary avenue. Cardiac MRI is likewise recommended to confirm a pattern consistent with MI.
Decompression Illness
Divers and high-altitude pilots, who rapidly transition from high- to depression-pressure level environments, may endure from decompression illness. Sudden changes in pressure causes nitrogen bubbles to form within tissues and accrue in the venous apportionment. These bubbles are filtered from the bloodstream through pulmonary capillary diffusion, but if a render to depression force per unit area (or ascent from depth for defined) is too rapid, then this pulmonary filtration process can be overwhelmed. Gas bubbles tin enter the systemic arterial circulation.[37] Bubbling continue to overstate, causing tissue trauma and fifty-fifty vessel apoplexy. There is a wide range of symptoms, from balmy musculus and joint pain, dizziness, fatigue, headache, rash and paraesthesia, to severe animate difficulties, confusion, motor incoordination and paralysis. A right-to-left shunt, such equally a PFO, allows nitrogen bubbling to bypass the pulmonary filter, increasing the risk that usually safe ascents will cause systemic embolisation.
Diving profiles are usually designed to limit the time at depth, and slowly ascend towards the surface, minimising the adventure of decompression illness. Occurence of decompression illines, despite utilise of condom dive profiles, implies an increased hazard of correct-to-left shunt. Investigation for atrial septal defect or PFO should be considered.[38,39] A longitudinal, non-randomised follow-up study showed that PFO closure reduced both symptomatic neurological events and total brain lesions among recreational divers with PFO and decompression illness, compared with those who continued to dive without closure.[40]
A contempo prospective registry evaluated 489 recreational divers for PFO using transcranial Doppler. This demonstrated that large PFO was a major independent gamble factor for unprovoked decompression illness (Hr 92; 95% CI [12.v-689]; p<0.001).[41] A recent study noted that in a cohort of 59 defined with decompression illness and PFO closure, iv continued to accept decompression disease over the 10-year follow-up period. This was shown to be due to residuum shunting, despite reported successful closure.[42] Where a professional diver wishes to continue diving, PFO closure could be recommended. Alternatively, discontinuation of diving or curtailing provocative dive profiles should be considered. If diving is recreational, then the risk–benefit assay for continued diving with a PFO closure is less articulate, and certainly procedural risk should be carefully weighed against the benefits of continuing to dive.
Platypnoea–Orthodeoxia Syndrome
Platypnoea–orthodeoxia syndrome is a rare status characterised by dyspnoea and positional desaturation in individuals with a PFO. In certain body positions, the geometry of the atrial septum is contradistinct, assuasive a continuous stream of deoxygenated blood from the junior vena cava to menses across the PFO. Deoxygenation is typically seen when the patient is seated, but oxygen saturations normalise when the patient lies apartment.[43] The distortion of the atrial septal geometry can be acquired past thoracic and cardiothoracic surgery, such as pneumonectomy, aortic dilatation and aortic surgery, or may not accept an identifiable cause.
Regurgitant jets from the tricuspid valve tin too exist directed across the PFO. Underlying cavity pressures do not affect platypnoea–orthodeoxia syndrome, and information technology responds well to PFO closure so long as pulmonary artery pressures are not markedly elevated. This is non usually the case. A 54-patient instance serial demonstrated that percutaneous closure was safe and effective for platypnoea–orthodeoxia syndrome.[44]
Migraine with Aura
Migraine is common in young people. Information technology is associated with aura in approximately one-third of cases.[45,46] Migraine with aureola has been associated with right-to-left shunts, such as PFO.[47,48] Large shunts are particularly associated with migraine with aureola.[49] Transfer of a vasoactive substance, usually filtered past the pulmonary circulation into the systemic circulation, is the proposed mechanism for the human relationship between migraine and PFO.[47]
A number of non-randomised studies reported improvement in patient symptoms after closure.[50] In the Migraine Intervention With STARFlex Technology (MIST) trial, patients with refractory migraine with aureola were randomised to either percutaneous PFO closure or a sham procedure. At that place was no difference in cessation of headache or reduction in headache-costless days. However, the trial population had a relatively low frequency of migraine, and a high frequency of residuum shunts later on closure – this trial used the same prosthesis as the negative CLOSURE ane stroke trial with similar bug. These confounders may have negatively influenced the trial effect.[51]
More recently, the Percutaneous Closure of PFO in Migraine with Aura (PRIMA) and Prospective Randomised Investigation to Evaluate Incidence of Headache Reduction in Subjects With Migraine and PFO Using the Amplatzer PFO Occluder Compared With Medical Management (PREMIUM) trials have reported their results.[52,53] Both studies were negative for their primary endpoints, although there were some reductions in headache. These furnishings were small and occurred at the expense of procedural complications. The show for PFO closure is not strong plenty to offer a routine recommendation for PFO closure in migraine with aura.
The Patent Foramen Ovale Closure Procedure
Pre-procedure Investigations
As cryptogenic stroke is the most common indication for closure, an emphasis should be placed on investigation looking for alternative causes of stroke. Cross-sectional brain imaging should be undertaken to confirm the diagnosis of an embolic stroke. Lacunar strokes are unlikely to exist embolic in nature.
AF is the most mutual source of thrombus, with studies suggesting that xiii% of patients with AF have cardiac thrombus.[54] In 90% of patients with non-valvular AF, the thrombus was located in the left atrial appendage.[54] The presence of AF in the context of a stroke is an indication for anticoagulation, and closure of a PFO is non indicated.
No study has shown that closure of a PFO confers additional do good. ECG monitoring is mandatory to exclude AF, and the duration depends upon the patient's risk factors. Nosotros recommend in young patients (<l years) with no risk factors, using a minimum of 72-60 minutes ambulatory surface electrocardiographic recording, and in those aged >fifty years, using 6 months of implantable loop recording. Implantable loop recording has the reward of extended rhythm surveillance; still, it is prone to fake positives and simulated negatives.[55–57] Conclusive evidence for the all-time strategy to diagnose AF is lacking. The loftier burden of supraventricular ectopics on ambulatory ECG or enlarged atrial size increases the likelihood of AF, and may indicate that an implantable loop recording is required in a younger patient.
Carotid imaging should exclude significant carotid plaque disease. Screening for thrombophilia should be considered, just its circuitous nature with inconsistent results means repeated investigations are often required. Thrombophilia oftentimes predisposes to venous rather than arterial thrombosis. Estimation of complex results tin can be hard, and should be undertaken in conjunction with haematologists who have a special interest in thrombosis.
The starting time-line investigation to exclude intracardiac thrombus is transthoracic echocardiography. A number of atmospheric condition, apart from AF, are associated with cardiac thrombus, which could embolise to crusade stroke. These include MI, left ventricular aneurysm, atrial myxoma, non-compaction cardiomyopathy, left ventricular failure and mitral stenosis. Prior to closure of PFO, these should all have been excluded as the potential source of the stroke.
A key investigation while working up patients with cryptogenic stroke is bubble contrast echocardiography. A PFO needs to produce a correct-to-left shunt to crusade a stroke. Bubble contrast studies are initially performed with transthoracic echocardiography, with no sedation necessary. Agitated saline is injected via a peripheral venous cannula (ideally placed in the lower body, simply the left antecubital fossa is commonly a more realistic option), while the patient releases a Valsalva manoeuvre or sniff. In the presence of a cardiac shunt, bubbles should announced in the left side of the centre within iii to four cardiac cycles of inflow in the right atrium. Later on advent of bubbles may reflect a pulmonary shunt. The written report should exist performed by an experienced operator. The procedure may require multiple repeats to confirm the diagnosis. Effigy one shows a bubble written report with transmission of bubbling from right-to-left. Transcranial Doppler is a non-invasive alternative to a dissimilarity echocardiogram. Information technology is a reliable method of assessing for the presence of a right-to-left shunt, although it does non delineate the anatomy of the PFO.[58,59]
A positive transthoracic chimera study or transcranial Doppler study after a cryptogenic stroke indicates the need for detailed transoesophageal echocardiography (TOE). A further bubble written report can exist undertaken using TOE if required. This allows the structural heart team to accurately determine the anatomy of the PFO. Assessment of a PFO is shown in Figure 1 . A TOE also allows the exclusion of alternative shunts, such as ventricular septal defects, anomalous pulmonary venous drainage or sinus venosus defects. A detailed guide to TOE assessment of PFO is outside the scope of this review, and is well reviewed elsewhere.[60]
Multiple specialties (including stroke physicians or neurologists, cardiac imaging specialists, radiologists and interventional cardiologists) are involved in diagnosis and handling decisions for cryptogenic stroke with PFO. Investigation should exist considered in a multidisciplinary setting, with a holistic arroyo to the management of the patient.
The Closure Procedure
Closure is performed as a day case procedure in many centres. The procedure can exist undertaken in a standard catheter laboratory using fluoroscopic guidance and physiological monitoring. Patients undergoing this process will have a reduced long-term risk of stroke, but obtain no immediate symptomatic do good from this procedure. Therefore, all possible steps to reduce complications should be taken.
In the opinion of the authors, the process should be, every bit far as possible, complication-costless, because fifty-fifty a small complication rate is likely to neutralise the benefit over optimal medical therapy. Ultrasound-guided femoral venous admission, echocardiographic guidance, adequate anticoagulation and special intendance to reduce the risk of air embolus are all important to ensure this goal.
Periprocedural guidance with TOE or intracardiac echocardiography is mandatory, in the opinion of the authors, to consistently achieve the best result.[61,62] Furthermore, it is considered mandatory within commissioning guidelines in the UK, and recommended in the Society for Cardiovascular Angiography and Interventions 2019 consensus statement.[63,64]
Although the process can be undertaken by very experienced operators with fluoroscopy lonely, echocardiographic guidance allows evaluation of interatrial septal anatomy, direct visualisation of the device position, and the relationship with aortic and mitral valves before device release. General anaesthesia is generally required to facilitate TOE, which may increase the cost and length of the process.
The process is undertaken from the femoral vein with ultrasound guidance for the puncture. Adequate anticoagulation (unfractionated heparin eighty–100 IU/kg) should be administered. A six-Fr multipurpose diagnostic catheter and a 0.035" J-tipped guidewire is used to cross the PFO and is passed into a pulmonary vein (usually the left upper pulmonary vein). This can and then be exchanged for a strong wire to help commitment of balloons.
Sizing of the PFO can be undertaken both before and after crossing with the wire, which may result in the PFO tunnel widening and shortening. Three-dimensional imaging software can be used to decide the maximum left and right atrial opening and minimum tunnel length. Balloon sizing of the PFO is usually not required, but can exist performed using quantitative angiographic tools, and confirmed with TOE or intracardiac echocardiography. A left anterior oblique cranial fluoroscopic project may assist with this, as the septum is seen in profile. Compliant balloons with marked graduations are used, but balloon sizing can even so shorten and widen the PFO. Shortening may exist desirable if there is a especially long PFO tunnel, only this can increase the size of the pigsty, necessitating a larger device. Factors that predispose to a larger device include PFO tunnel length, the presence of atrial septal aneurysm and male person sex.[65] Precise sizing will depend upon the option of device used.
Once sizing is completed, an appropriate device (with delivery sheath) tin can be passed into the left atrium through the PFO. The left atrial disc is deployed, followed by the right disc. Ensuring that the commitment sheath remains de-aired and flushed throughout the procedure minimises the adventure of air or thrombotic embolism. After the device is deployed, confirmation of the acceptable position with echocardiography and fluoroscopy should exist performed prior to device release. If the device is malpositioned after release, a big gooseneck snare can be used to recover the device. The steps involved in a PFO closure process are shown in Figure 2 .
The Patent Foramen Ovale Closure Procedure
A wire crossing a patent foramen ovale into the left upper pulmonary vein with a Judkins Correct 4 catheter (white arrow) is shown (A). The delivery sheath (blue pointer) is avant-garde through the patent foramen ovale over the stiff wire (B), and the device – a Gore Cardioform septal occluder – is deployed (C,D) with the left atrial disc (dark-green arrow) deployed first and so apposed to the atrial septum. The right atrial disc (black pointer) is then deployed, only the device is not released until the operator is happy with the position both fluoroscopically and with echocardiography. A released device is shown (E; xanthous pointer) using 3D transoesophageal echocardiography (F; imperial arrow) viewed from the left atrium.
Prove for antiplatelet therapy after device deployment remains incomplete. Device thrombosis remains a feared complication of PFO closure. In our practice, aspirin and clopidogrel are unremarkably given for 6 months, only evidence for this is limited and do varied markedly betwixt trials. Earlier discontinuation of dual antiplatelet therapy was associated with an increased frequency of pocket-sized cerebrovascular events in a study level meta-analysis of PFO closure trials.[66] Long-term observation studies have suggested this is a safe practice.[33]
Some operators preload patients with antiplatelets, but again, the evidence for this is uncertain. Single antiplatelet therapy, usually clopidogrel 75 mg daily, is continued indefinitely, as the device may take up to 5 years to endothelialise. The European Association for Percutaneous Cardiovascular Interventions consensus statement recommends this approach at present.[66]
Follow-up is important, but doubt remains nigh the appropriate timeframe. As most devices endothelialise over a flow of approximately 6 months, then a repeat bubble study could be considered at that stage. Timing is of item relevance where the PFO has been closed for occupational reasons, such every bit professional diving.
Closure Devices
A large number of devices with varying shape and size have been marketed. Many accept received CE mark condition in the EU. In the Usa, fewer devices have been approved by the Food and Drug Administration, due to the need for randomised evidence prior to blessing.
Most devices are of double-disc pattern, connected by a short waist. The Gore Septal Occluder (WL Gore and Associates) and the Amplatzer PFO Occluder (Abbott Vascular) are two of the more commonly used devices and are shown in Figure 3 . The Gore Septal Occluder is constructed from v nitinol wires covered with expanded polytetrafluoroethylene.[67] Early clinical experience has shown that it is a versatile device with easy deployment, high procedural success and depression complication rates.[68,69] The Amplatzer PFO Occluder is besides a nitinol-based device. This device has been used most unremarkably in randomised clinical trials. The evidence base for its use is therefore very stiff.[21,22] There are numerous other commercially bachelor devices, including the Occlutech PFO occluder (Occlutech International) and Ultrasept (Cardia), plus suture-based technologies, such as NobleStitch (HeartStitch).
Devices Approved for Patent Foramen Ovale Closure
A: Ceraflex PFO Occluder. B: Gore Cardioform Septal Occluder. C: Figulla Flex II Occluder. D: Amplatzer PFO Occluder. E: Ultrasept PFO Closure Device. These devices are canonical for patent foramen ovale closure, with the Amplatzer and Gore devices near widely deployed.
Future Directions
There are a number of outstanding research questions regarding PFO closure that need to be answered. First, the optimal antiplatelet or anticoagulation regimen balancing the risk of recurrent stroke or embolism against the risk of bleeding needs to be established. Electric current guidance is based on consensus statements and the strategies adopted in the clinical trials mentioned earlier. Meta-analyses have not shown whatever clear additional benefit for anticoagulation when PFO is non closed subsequently stroke.[70] Further studies evaluating the do good of anticoagulation and optimal elapsing of dual antiplatelet therapy would exist welcome. Simplification of the procedure with the use of non-invasive echocardiography may exist attractive, but is not recommended in consensus statements.[64] A clinical trial to establish the safety and efficacy of a fluoroscopic approach with transthoracic echocardiography support is currently underway ({"blazon":"clinical-trial","attrs":{"text":"NCT03828825","term_id":"NCT03828825"}}NCT03828825).
Identification of a high gamble of PFO-associated stroke prior to the first stroke remains the golden ticket. Some have published studies with scoring systems to identify loftier-risk PFO, only these have non identified patients prior to cryptogenic stroke, when the PFO is commonly silent.[71] Patients with inherited thrombophilia found to take PFO may be candidates for condom PFO closure. Observational studies have suggested that those in this group who have a PFO closure have a reduced incidence of stroke or transient ischaemic attack.[72] Randomised trials to appraise whether this group would do good are needed, just volition exist challenging to recruit, given the relatively pocket-sized numbers of patients in this group.
A recent observational study of patients undergoing surgery found a significantly college incidence of ischemic stroke over a 1-yr menstruum in those with PFO.[73] This run a risk was mitigated for those receiving dual antiplatelet therapy or anticoagulation, or those who had undergone PFO closure. These observational information are hypothesis generating, but suggest that there may be a population that could be identified to benefit from upfront closure, only further well-designed clinical trials would be required to justify this against the procedural risk.
Furthermore, there are express data to back up differences in handling by subgroup. A meta-analysis of trials reporting outcome by sex (RESPECT, REDUCE, CLOSURE 1) suggested that at that place was a significant reduction in men, and a non-significant numeral reduction in stroke for women. The majority of patients treated in these studies were men. Further work is required to identify whether in that location are meaningful differences in these groups. Similarly, differences between ethnic groups could too be examined.
Finally, expansion to other indications, particularly for migraine relief requires a better quality of evidence. The planned GORE CARDIOFORM Septal Occluder Migraine Clinical Written report (RELIEF study) is a sham randomised controlled trial of PFO closure for migraine relief with recruitment due to start in 2020. A sham procedure is important to tease out the stiff placebo effect associated with migraine studies ({"type":"clinical-trial","attrs":{"text":"NCT04100135","term_id":"NCT04100135"}}NCT04100135).
Conclusion
In this review, the main indications for PFO closure have been discussed (cryptogenic stroke, paradoxical systemic embolisation, platypnoea–orthodeoxia syndrome and decompression illness), together with the strengthening evidence for closure. The skills required for this procedure need to be learnt with the assistance of experienced interventional cardiologists who can proctor and advise those starting out with PFO closure. Attention to detail in the indication for the procedure, and minimising the risks to the patient during the closure are key to an constructive PFO closure service.
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