Patent Foramen Ovale Closure: Stroke Protection and New Horizons

What is a Patent Foramen Ovale (PFO)?

A patent foramen ovale (PFO) is a small opening in the interatrial septum of the heart, which is a normal structure during fetal development. It allows blood to bypass the lungs, which do not function before birth. Normally after birth, when the baby takes its first breath, pressure in the left atrium increases, and the oval foramen closes, forming the fossa ovalis. However, in approximately 25% of the adult population, this opening remains patent [3]. In most cases, a PFO causes no symptoms and requires no treatment. The problem arises when small blood clots can pass through this opening from the venous system into the arterial system, bypassing the pulmonary filter, which can lead to a stroke.

PFO and Cryptogenic Stroke: Connection and Risks

The connection between a patent foramen ovale and ischemic stroke, especially so-called cryptogenic stroke (for which no cause has been established), is actively being studied. A PFO is frequently detected in young patients with ischemic stroke [6]. The mechanism by which a PFO can cause a stroke is called paradoxical embolism: a blood clot formed, for example, in the veins of the legs can pass through the PFO from the right atrium to the left, and then enter the systemic circulation and cause a blockage of cerebral blood vessels [3].

Numerous randomized clinical trials and meta-analyses in recent years confirm that transcatheter PFO closure significantly reduces the risk of recurrent stroke in carefully selected patients with cryptogenic stroke compared to medical therapy alone [3, 5, 8]. For example, long-term follow-up results from the RESPECT trial demonstrated the superiority of PFO closure over medical management, leading to regulatory approval of PFO closure devices [8].

Diagnosis of a Patent Foramen Ovale

Various imaging modalities are used to accurately diagnose a PFO and assess its characteristics:

• Transesophageal Echocardiography (TEE): Considered the gold standard. It allows detailed visualization of the interatrial septum, determination of the PFO size, presence of a shunt, and its features, such as tunnel length [1, 3].
• Contrast Transcranial Doppler (TCD): Can be used as a screening tool. When a contrast agent (saline agitated with air) is injected via a vein, TCD detects microbubbles passing through the PFO into the cerebral arterial vessels, indicating a right-to-left shunt [2].
• Intracardiac Echocardiography (ICE): This method is becoming increasingly popular, especially in cases where fluoroscopy (X-ray radiation) and general anesthesia need to be avoided, such as in pregnant patients. ICE enables the PFO closure procedure to be performed under direct ultrasound guidance without the use of contrast or X-rays [4].

PFO Closure Procedure: Modern Methods

Patent foramen ovale closure is most commonly performed via a transcatheter approach, which is a minimally invasive procedure. During the procedure, a thin catheter is inserted through a vein (usually the femoral vein) and advanced to the heart under imaging guidance (TEE or ICE). A special occluder device is then deployed through the catheter to close the PFO. These devices typically consist of two discs that anchor on either side of the interatrial septum, securely sealing the opening [3].

Among the devices used are the GORE Cardioform Septal Occluder and the AMPLATZER™ septal occluder, which have demonstrated efficacy and safety [1, 8]. In some cases, such as in pregnant women with acute ischemic stroke, the procedure can be performed entirely without fluoroscopy, using only intracardiac echocardiography under local anesthesia, thereby minimizing risks to the mother and fetus [4].

Who is a Candidate for PFO Closure?

The decision to close a PFO is made individually and requires careful evaluation. The primary indication is secondary prevention of cryptogenic ischemic stroke, particularly in young and middle-aged patients (18–60 years old) with no other identified causes of stroke [6, 8]. Anatomical features of the PFO, such as the presence of a long tunnel or a large shunt, which may increase the risk of paradoxical embolism, are also important [1, 3, 4, 6].

Beyond stroke, other potential indications are being explored:

• Migraine: Recent studies indicate that PFO closure may be effective in reducing the frequency and intensity of migraine attacks in children. In one study, 80% of children achieved complete resolution of migraines or a reduction in attack frequency by more than 50% at 12 months post-procedure [7].
• Elderly Patients: The efficacy and safety of PFO closure in elderly patients require further investigation, as they may have other stroke risk factors unrelated to PFO [2, 6].

It is important that the decision to close a PFO is made by a multidisciplinary team, including cardiologists and neurologists, to weigh all risks and benefits [4, 6].

The Future and Special Cases

The field of PFO study and closure continues to evolve. New patient selection algorithms are being investigated that take into account the likelihood of a causal link between the PFO and stroke [6]. Research is also evaluating the efficacy and safety of PFO closure in special patient groups, such as the elderly, and studying long-term outcomes, including the risk of post-procedure atrial fibrillation [6].

Cases involving rare congenital anomalies, such as incomplete cor triatriatum sinister, also demonstrate the feasibility of successful transcatheter PFO closure, expanding the spectrum of patients who can be helped [1]. Work continues on optimizing devices and techniques to enhance procedure safety and efficacy.

Sources

• 1. Percutaneous Closure of Patent Foramen Ovale in a Patient With Incomplete Cor Triatriatum Sinister: A Case Report. https://pubmed.ncbi.nlm.nih.gov/41957543/
• 2. Asian-Pacific Expert Opinion on Patent Foramen Ovale Closure: Review of New Evidence and Focused Update. https://pubmed.ncbi.nlm.nih.gov/41084288/
• 3. Patent foramen ovale closure for secondary stroke prevention. https://pubmed.ncbi.nlm.nih.gov/30957864/
• 4. Zero-fluoroscopy, intracardiac echocardiography-only patent foramen ovale closure in early pregnancy: a case report. https://pubmed.ncbi.nlm.nih.gov/42725154/
• 5. Patent foramen ovale closure versus medical therapy for stroke prevention: A systematic review and meta-analysis of randomized controlled trials. https://pubmed.ncbi.nlm.nih.gov/30271571/
• 6. Patent Foramen Ovale Management for Secondary Stroke Prevention: State-of-the-Art Appraisal of Current Evidence. https://pubmed.ncbi.nlm.nih.gov/38134261/
• 7. Clinical efficacy of percutaneous closure of patent foramen ovale in children diagnosed with migraine. https://pubmed.ncbi.nlm.nih.gov/40529558/
• 8. Role of PFO Closure in Ischemic Stroke Prevention. https://pubmed.ncbi.nlm.nih.gov/31724077/

Disclaimer: The information provided in this article is for informational purposes only and cannot replace professional advice, diagnosis, or treatment provided by a qualified medical specialist. Always consult a physician regarding any questions you may have about your health or medical condition.