A patent foramen ovale (PFO) closure is a minimally invasive medical procedure designed to seal a small, flap-like opening situated between the upper chambers of the heart. The intervention uses a cardiac catheterization technique, avoiding open-heart surgery. The primary goal of the PFO closure is to prevent abnormal blood flow between the heart’s right and left atria by implanting a permanent sealing device. The decision to undertake this procedure is based on specific medical circumstances, often related to the risk of stroke.
Understanding Patent Foramen Ovale
The foramen ovale is a temporary structure present in the heart of every fetus, representing a necessary opening between the right and left atria. This opening allows oxygenated blood from the placenta to bypass the non-functional fetal lungs, routing blood directly to the systemic circulation.
When a newborn takes its first breath, pressure increases in the left atrium as blood returns from the newly inflated lungs. This pressure change naturally pushes the thin flap of tissue (septum primum) against the septum secundum, effectively closing the foramen ovale. In approximately 75% of individuals, this functional closure becomes an anatomical seal over the first few months of life.
When the flap fails to seal completely, the communication persists into adulthood and is termed a patent foramen ovale. The opening remains “patent,” or open, creating a potential pathway for blood to pass between the atria. A PFO is considered a remnant of normal fetal anatomy rather than a traditional hole in the heart tissue, which distinguishes it from an atrial septal defect.
When Closure Becomes Necessary
The primary reason physicians recommend PFO closure is to reduce the risk of recurrent stroke, especially in cases classified as cryptogenic stroke (CS)—an ischemic stroke of undetermined cause where a PFO is the only potential mechanism identified. The mechanism involves paradoxical embolism, where a blood clot originating in the venous system, such as the legs, travels to the right side of the heart. Instead of being filtered by the lungs, the clot passes through the PFO from the right atrium to the left atrium, from which it can travel to the brain and cause a stroke.
The strongest evidence for closure is found in younger patients, typically under the age of 60, who have experienced a CS and possess high-risk PFO features. These features include a large right-to-left shunt or the presence of an atrial septal aneurysm (a bulging interatrial septum).
PFO closure may also be considered for other conditions associated with paradoxical embolism or shunting, such as decompression sickness in scuba divers. In divers, pressure changes can cause nitrogen bubbles to form in the blood; if these cross a PFO, they can cause decompression illness. Some patients with specific types of migraine, particularly migraine with aura, have also explored PFO closure, though the evidence supporting this indication is not as definitive as for stroke prevention.
Details of the Closure Procedure
The PFO closure is a transcatheter procedure performed in a cardiac catheterization laboratory, typically lasting between one and two hours. The patient receives sedation or general anesthesia to ensure comfort throughout the process. Access to the heart is usually gained through a small incision in the groin, where an introducer sheath is inserted into the femoral vein.
A long, thin, flexible tube called a catheter is then carefully threaded through the vein and guided under fluoroscopic (X-ray) and echocardiographic imaging up to the heart. Imaging tools like transesophageal echocardiography (TEE) or intracardiac echocardiography (ICE) are used to visualize the PFO, confirming its size and location. A sizing balloon may be used to accurately measure the dimensions of the opening to select the appropriately sized closure device.
Once the measurements are complete, the chosen occlusion device is collapsed and loaded onto a delivery catheter. The closure device is commonly a double-disk, self-expanding implant made from a nickel-titanium alloy, designed to straddle the PFO like a sandwich. The first disk is deployed on the left atrial side of the septum, pulled gently against the wall, and then the second disk is deployed on the right atrial side, securing the device in place.
After the cardiologist confirms the stability and correct position of the implanted device using imaging, the delivery catheter is detached and withdrawn. The implanted device remains permanently in the heart, creating an immediate mechanical barrier to prevent blood from flowing across the PFO. The small incision site in the groin is then closed, completing the minimally invasive procedure.
Life After the Procedure
Following the procedure, patients are typically required to lie flat for several hours to allow the access site in the femoral vein to seal properly. Most individuals are discharged from the hospital within 24 hours of the intervention. Patients are generally advised to avoid strenuous activity, heavy lifting, and intense exercise for a few days to a week to promote healing of the groin incision.
A structured follow-up plan is established to monitor the device and the patient’s recovery. This usually involves taking a course of anti-platelet medication, often a combination of aspirin and a second agent like clopidogrel, for a prescribed period. This dual therapy is generally continued for a minimum of six months to a year.
Anti-platelet medication prevents blood clots from forming on the newly implanted metal device while the body heals. During this time, the heart’s lining (endothelium) grows over the closure device, a process called endothelialization. Once the device is fully covered, the risk of device-related clotting diminishes, and the anti-platelet regimen can often be simplified.