A patent foramen ovale (PFO) is a small, flap-like opening between the heart's two upper chambers, which serves as a remnant from the prenatal period, allowing blood to bypass the lungs. In most individuals, this opening seals shut during infancy; however, approximately 1 in 4 adults retain an open PFO. For the vast majority, it poses no health issues and typically requires no treatment.
Nonetheless, in some individuals—especially those who have experienced a stroke or transient ischemic attack (TIA) at a young age without any other identifiable cause—a PFO can serve as a conduit for small blood clots to transit from the right side of the heart to the left, potentially reaching the brain. In such cases, a thorough cardiac assessment is vital, as in carefully selected patients, PFO closure using a minimally invasive procedure can substantially lower the risk of future strokes and improve stroke prevention efforts.
Before birth, every baby has an opening — the foramen ovale — between the heart's upper chambers, allowing blood to bypass the lungs, which aren't yet in use. After birth, the two overlapping flaps of tissue normally fuse together within the first months of life. In about 25% of people, however, the flaps never fully fuse, resulting in a patent foramen ovale (PFO). While this PFO typically remains functionally closed due to higher pressure in the left side of the heart, it can transiently open during straining, coughing, or certain pressure changes, permitting blood to flow directly from the right side to the left and bypass the lungs' natural filter. A PFO is not considered a
Stroke and TIA are major concerns in cardiac assessment. The lungs typically filter small clots from the venous circulation before blood reaches the brain. However, a PFO can provide a bypass route, allowing a small clot to cross through it and potentially travel to the brain, resulting in a stroke. This mechanism, known as paradoxical embolism, is particularly relevant in younger patients (typically under 60) who have experienced a stroke or TIA without a clear cause found despite thorough investigation, often referred to as a "cryptogenic" stroke. In this demographic, the presence of a PFO is significantly more common than chance would predict, and major randomized trials have indicated that PFO closure can drastically reduce the risk of recurrent stroke compared to medication alone in appropriately selected patients, serving as an effective stroke prevention strategy.
Regarding migraine with aura, a PFO is more frequently seen in individuals suffering from this condition. Some patients report improvement in their symptoms after undergoing PFO closure for other medical reasons. However, trials focusing on closure specifically for migraine have not consistently demonstrated sufficient benefit to establish it as a routine indication — I always strive to provide an honest appraisal of the evidence.
For divers, a PFO poses risks as it allows venous nitrogen bubbles to bypass the lungs, thereby heightening the chances of decompression sickness. Divers experiencing unexplained or recurrent decompression illness should undergo PFO assessment, as closure may facilitate a safe return to diving in selected cases.
Other situations, such as experiencing low oxygen levels when upright (platypnoea-orthodeoxia) and concerns prior to certain surgeries, are less frequent but are well recognized.
If your PFO was discovered incidentally during a scan and you have not experienced a stroke or related problem, treatment is typically unnecessary. In most cases, reassurance is the appropriate outcome, and I will communicate this clearly.
Your first appointment lasts up to 30 minutes and includes a comprehensive cardiac assessment to understand the significance of the PFO in your specific case — including details about your stroke or TIA work-up, neurology findings, diving history, or other relevant context. We will conduct a review of your imaging to determine how the PFO was discovered and what is already known about its anatomy. Additionally, a physical examination and resting ECG will be performed in the clinic. You will receive a clear and honest recommendation regarding PFO closure — specifically whether it is genuinely indicated for you, if medication alone would be a better option, or if no treatment is necessary. For those patients who have experienced a stroke, I collaborate closely with your neurologist since the decision to pursue a PFO closure for stroke prevention is ideally a joint cardiology–neurology decision, and I will ensure that this coordination is effective.
The bubble echocardiogram (bubble study) serves as the key screening test in cardiac assessment; agitated saline is injected into an arm vein while imaging the heart. Bubbles crossing to the left side reveal the patent foramen ovale (PFO) and help grade the size of the shunt, often with a strain maneuver to open the tunnel. The transoesophageal echocardiogram (TOE) involves passing an ultrasound probe into the food pipe under sedation, providing detailed views of the PFO anatomy, tunnel length, and surrounding septum. This procedure is essential for confirming the diagnosis, excluding an atrial septal defect (ASD), and planning for potential PFO closure. In the context of stroke prevention, ambulatory ECG monitoring is crucial after a stroke to exclude atrial fibrillation as the true cause before attributing the event to a PFO. Additionally, blood tests, including thrombophilia screening when indicated, are conducted in coordination with your stroke team. Most patients complete their assessment within one to two weeks.
No treatment is often the right approach for most incidentally found PFOs. A PFO in someone without related issues is considered a normal variant, not a disease.
For some stroke patients, a cardiac assessment may reveal that medication alone is appropriate. Antiplatelet or anticoagulant medication without closure can be suitable depending on factors such as age, the certainty that the PFO was culpable, and overall risk. These considerations are discussed transparently in a joint decision-making process.
PFO closure is recommended for selected patients, particularly those who have experienced a PFO-related stroke or TIA. The procedure involves:
- Performing the closure through a vein at the top of the leg, eliminating the need for a chest incision or heart-lung machine.
- A small, double-disc closure device is positioned across the tunnel, effectively sealing it. Over the next few months, heart tissue grows over the device, making it a permanent part of the heart wall.
- The procedure typically lasts under an hour and is performed under local anaesthetic with sedation or a short general anaesthetic.
- Most patients can go home the same day or the following morning and often return to normal activities within days.
- Following the closure, aspirin and/or clopidogrel are prescribed for a period while the device heals in, along with a follow-up echocardiogram to confirm complete closure.
PFO closure is one of the safest procedures in structural cardiology, boasting a very low complication rate when performed by experienced hands. The most common issue is a transient irregular heartbeat (atrial fibrillation) in a small percentage of patients during the weeks post-procedure, which typically resolves on its own. This innovative approach plays a key role in stroke prevention for eligible patients.
Structural heart intervention is my subspecialty as a Consultant Interventional and Structural Cardiologist, specializing in keyhole structural procedures at leading centers. My approach emphasizes honest cardiac assessment; my primary goal is to determine whether your PFO closure is genuinely warranted. Many consultations conclude with reassurance rather than an unnecessary procedure. I work closely with neurology to ensure stroke prevention decisions are made correctly in collaboration with your stroke physician or neurologist. I hold a PhD from King's College London, completed a structural intervention fellowship at San Raffaele Hospital in Milan, and have authored over 100 peer-reviewed publications. I offer rapid access with same-week appointments available at Heart Health Welbeck London (Marylebone), Cromwell Hospital (Kensington), The Wellington Hospital (St John's Wood), Bupa Health Care Canary Wharf, and The Essex Cardiothoracic Centre (Basildon). Consultations are available in both English and Turkish. I am recognized by all major private medical insurers, and self-paying patients are welcome.
A PFO raises one essential question — is it relevant to you? An expert cardiac assessment provides a clear answer and outlines the appropriate treatment, such as PFO closure, if necessary for effective stroke prevention. To arrange a consultation at one of my London or Essex locations, please contact my practice team.
Reach out to Ms. Melinda Ziff (PA) at 020 3198 9826 or drozandemir.sec@outlook.com to schedule your consultation.