A Patent Foramen Ovale (PFO) is a common heart condition: a small opening between the heart’s two upper chambers, the right and left atria. This opening is present before birth but typically closes shortly after. For many, this flap-like opening does not fully seal, yet often causes no symptoms.
Understanding Patent Foramen Ovale
During fetal development, the foramen ovale serves a crucial purpose, allowing blood to bypass the lungs, which are not yet functional. This opening facilitates oxygenated blood flow from the placenta. At birth, as a newborn takes its first breaths, pressure changes occur within the heart, ideally causing the foramen ovale to close permanently. When this natural closure process is incomplete, a PFO persists, forming a small, flap-like tunnel between the atria. This anatomical variation is quite prevalent, found in approximately one in four adults, meaning about 25% of the general population has a PFO. Despite its commonality, the majority of PFOs are considered benign and do not lead to any discernible health issues or symptoms.
Does a PFO Worsen Over Time?
The physical opening of a PFO typically does not enlarge or “worsen” in size over time in most adults. The anatomical structure of the PFO, essentially a small flap, tends to remain stable in its dimensions. While the hole may not physically expand, the risks associated with its presence can become more apparent or significant due to other evolving health factors. The amount of blood shunting, or flowing through the PFO from the right atrium to the left atrium, can vary. This variation in shunting might be influenced by temporary changes in pressure within the heart, such as during coughing or straining. However, fluctuations in shunting do not necessarily indicate that the PFO itself is structurally worsening. For the vast majority of individuals, a PFO remains asymptomatic and does not progress to cause problems.
Potential Complications Associated with PFO
While a PFO usually does not worsen, its presence can be associated with certain health complications. One of the most significant associations is with cryptogenic stroke or transient ischemic attack (TIA), which are strokes or “mini-strokes” with no clear cause. A PFO can potentially allow a blood clot, originating in the venous system (e.g., from the legs), to pass from the right side of the heart to the left side through the PFO, bypassing the lungs’ filtering system. This clot can then travel to the brain, causing a paradoxical embolism.
Another observed association is between PFO and migraine with aura, a specific type of migraine preceded by sensory disturbances. While the exact mechanism is not fully understood, some theories suggest that substances or small clots that would normally be filtered by the lungs might cross the PFO and trigger migraine attacks.
For divers, a PFO carries relevance concerning decompression sickness. During ascents, nitrogen bubbles can form in the blood; if these bubbles pass through a PFO, they can bypass the lungs and travel to the brain or other organs, leading to neurological or other symptoms. Less common associations include platypnea-orthodeoxia syndrome, a rare condition where shortness of breath and low blood oxygen levels worsen when sitting or standing upright.
When is PFO Intervention Considered?
Intervention for a Patent Foramen Ovale, such as PFO closure, is not routinely recommended for individuals who have an asymptomatic PFO. The decision to consider closure is typically made after a thorough medical evaluation and depends on specific clinical circumstances. The primary indication for PFO closure is often for secondary stroke prevention, particularly in younger patients who have experienced a cryptogenic stroke or TIA where a PFO is identified as the likely cause.
Diagnostic methods, such as a transthoracic echocardiogram with a bubble study or a transesophageal echocardiogram, are used to confirm the presence and characteristics of a PFO. If closure is deemed appropriate, the procedure is typically catheter-based, involving a device delivered through a vein to seal the opening. Other, less common reasons for considering PFO closure include recurrent severe decompression sickness in divers or specific cases of platypnea-orthodeoxia syndrome that significantly impact a person’s quality of life.