What You Should Know About Patent Foramen Ovale (PFO)
and Its Relevance in Stroke and Other Health Risks
🫀 Patent Foramen Ovale (PFO)
Definition: PFO is a small, flap-like opening in the heart that failed to close after birth. In fact, everyone starts out life with a Patent Foramen Ovale or PFO (“open oval hole” in Latin) in their heart. It’s been like this through evolution, not just in humans but all mammals as well.
🫁 The anatomy and pathophysiology of PFO :
Before birth, a fetus receives oxygenated blood from the mother’s placenta while its lungs are still developing. The PFO allows this oxygen-rich blood to pass from the right to left sides of the heart and then to circulate around the body. After birth, blood from the right chambers of the heart heads to the lungs for oxygen, returns to the left chambers, and is circulated. At this point, the PFO is no longer needed; fibrous tissue closes it up in most people during the first year of life.
🧠 But what happens when this doesn’t close completely and a PFO remains?
While common in the general population, PFO is linked to several medical conditions, notably ischemic stroke, due to paradoxical embolism where blood clots bypass the lungs and reach the brain.
PFO and Stroke
PFO-Associated Stroke: PFO is a significant risk factor for ischemic stroke, particularly cryptogenic strokes, where the cause is not otherwise identified. It accounts for approximately 1 in 20 ischemic strokes.
Diagnosis and Risk Assessment: Neurologists utilize the following PFO-Associated Stroke Causal Likelihood classification systems to determine the likelihood of PFO being the cause of a stroke and whether PFO closure may be beneficial.
Patent Foramen Ovale-Associated Stroke Causal Likelihood (PASCAL)
Risk of Paradoxical Embolism (ROPE) Score
Diagnostic Techniques
Various imaging techniques are employed to diagnose PFO, each with unique advantages:
Transthoracic Echocardiography (TTE)
Transesophageal Echocardiography (TEE)
Transcranial Doppler (TCD)
Other Health Risks
Migraines: There is evidence linking PFO with migraine headaches, particularly migraines with aura, though the exact mechanism remains under study. Clinical trials are ongoing to explore this connection further.
Hypoxemia: PFO is associated with conditions such as platypnea-orthodeoxia syndrome, where posture-related oxygen desaturation occurs.
Acute Mountain Sickness (AMS): PFO may exacerbate AMS due to worsened hypoxemia at high altitudes.
Decompression Illness (DCI): Divers with PFO are at higher risk for DCI due to nitrogen bubbles bypassing the lungs, potentially leading to serious complications.
Management and Treatment
PFO Closure: Percutaneous device closure is now a well-established treatment to prevent recurrent strokes in patients with a high risk of paradoxical embolism. The procedure is guided by various imaging modalities, including TEE and intracardiac echocardiography.
Preventative Measures: Regular screening and appropriate behavioral and medical management (medications) are available. These interventions can mitigate the health risks associated with PFO after a comprehensive work-up and discussions with your clinical care teams. These may include a neurologist, cardiologist and hematologist.
The Science of PFO in 2025
Understanding the role of PFO in various health conditions is crucial for effective management and prevention strategies. Continuous research and advancements in diagnostic techniques are enhancing our ability to identify and treat PFO-associated conditions, improving patient outcomes. Research is still our best method to improve the science as well as gaining insights from the patients with lived-experience from a PFO associated stroke.
Some of this current research and advocacy on PFO closure was initially shaped by patients wanting more options for a better quality of life after cryptogenic stroke with PFO. I was one of them.
I’ve shared my own story here on Substack on my patient testimony before the FDA for the RESPECT Trial and am currently writing a book on closure after stroke.
We’ll also be covering a deep dive of the topic of PFO and Stroke in an upcoming episode of the Know Stroke Podcast so be sure to subscribe here or follow the show on your favorite podcast player!
Hi David,
I'm also a stroke survivor with a PFO. I'm sure you're aware that there's a lot of controversy around whether they should be closed after a stroke. I did have mine closed, after consulting two cardiologists.
I'd love to read your book. I've read a lot of stroke survivor books, and the only one that I can remember discussing PFO closure is Tedy Bruschi's "Never Give Up", and that mentions it only briefly.
Regards,
Mark Brodie