Surgical Risks with an Uncorrected PFO or ASD Explained

Yes, you absolutely must tell your entire surgical team—especially your anesthesiologist—if you have an uncorrected patent foramen ovale (PFO) or atrial septal defect (ASD). You should disclose this during your pre-operative assessment (weeks before surgery) even for minor procedures like colonoscopies or dental work requiring IV sedation. Having an open communication between the upper chambers of your heart slightly increases your risk of perioperative complications, primarily a type of stroke caused by a paradoxical embolism ^[1][2][3]. By knowing about your heart anatomy in advance, your medical team can take strict, highly effective safety precautions during your procedure to protect you.

Understanding the Risk: Paradoxical Embolism

During surgery, it is relatively common for tiny blood clots or microscopic air bubbles to form in your veins. In a typical heart, these travel to the lungs, which act as a natural filter and safely absorb them. However, if you have a PFO or ASD, these particles can bypass the lungs by slipping through the hole from the right side of the heart to the left ^[4][5]. Once on the left side, they are pumped out to the rest of the body. If one of these particles reaches the brain, it can block blood flow and cause a stroke ^[3][5].

While these complications are rare, research shows the risk of ischemic stroke, longer hospital stays, or readmission is slightly higher for PFO and ASD patients compared to those without these conditions ^[2][6]. This is why your condition requires specialized care—but with the right precautions, these risks can be effectively managed.

Precautions Your Anesthesia and Surgical Teams Will Take

When your care team knows about your PFO or ASD in advance, they will modify their approach to your anesthesia and surgical plan to minimize your risks.

• Strict Intravenous (IV) Line Management: The primary concern during surgery is preventing air from entering your venous system. Your anesthesiologist will be meticulous about clearing every visible air bubble from your IV lines and medications ^[7][5]. Because securing specialized equipment takes time, telling them early allows them to order special air-eliminating filters for your IV tubing to ensure no microscopic bubbles can cross the hole in your heart.
• Ventilation and Breathing Adjustments: The way a breathing machine (mechanical ventilator) pushes air into your lungs temporarily changes the pressure inside your chest ^[8][9]. This positive pressure can sometimes increase the pressure on the right side of your heart, forcing blood (and potential clots or bubbles) backward through the PFO or ASD. Your anesthesiologist will carefully monitor and adjust the ventilator settings to balance your oxygen needs while keeping right-sided heart pressures as stable as possible ^[10].
• Safer Surgical Positioning: The physical position of your body during surgery matters. Certain positions, particularly sitting upright (often used in shoulder or neurosurgeries), can alter the heart’s anatomy or use gravity to worsen the right-to-left flow of blood across a PFO ^[11][12]. The team will take extra precautions or potentially adjust your position to maintain optimal blood flow.
• Enhanced Blood Clot Prevention: Because surgical patients are already at a higher risk of forming blood clots due to prolonged immobilization, your team will prioritize blood clot prevention. This often means utilizing special compression boots and—when appropriate and safe for your specific type of surgery—blood-thinning medications ^[6].

What You Can Do to Protect Yourself

While your medical team manages your safety in the operating room, you also play an active role in your recovery. To help prevent blood clots before and after surgery:

• Stay hydrated: Drink plenty of fluids as directed by your doctor before the fasting period begins, and resume drinking as soon as you are cleared after surgery.
• Get moving: Walk and move around as soon as your surgical team says it is safe. Movement is one of the best ways to keep blood flowing in your legs and prevent clots.
• Know the warning signs: After you go home, seek immediate medical attention if you experience sudden numbness, weakness on one side of your face or body, difficulty speaking, severe sudden headache, or sudden swelling, redness, and pain in one of your legs.