What Is Atrial Septal Aneurysm? Symptoms, Causes, and Treatment
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is an atrial septal aneurysm and should I worry?
An atrial septal aneurysm is a common, birth-related bulge of extra tissue in the wall between the heart's two upper chambers. By itself it is not a cause for concern, and many people never know they have it. It needs attention only with stroke risk factors such as a patent foramen ovale. [9] Life expectancy appears normal. [9]
What the research says
According to PubMed:
It is found by chance in a small share of adults who get a heart ultrasound. Among 16,570 adults who had a transthoracic echocardiogram at one outpatient clinic, atrial septal aneurysm (defined as septal protrusion of more than 15 mm) was documented in 393 people (2.4%); valve leakage and supraventricular arrhythmias were common alongside it, with supraventricular arrhythmia in 61 people (16%) (Yetkin et al., Int J Cardiol, 2016) [7].
Some heart rhythm problems are more common with it. In a study of 641 people with atrial septal aneurysm and 641 matched controls, atrial premature complexes, ventricular premature complexes, supraventricular tachycardia, and paroxysmal atrial fibrillation were each more frequent in the aneurysm group and independently associated with it (Yetkin et al., Scand Cardiovasc J, 2020) [8].
It may matter most after a stroke of unclear cause. In a Japanese registry of 671 people with cryptogenic stroke, atrial septal aneurysm was found in 92 (14%); in-hospital stroke recurrence was 8% with the aneurysm versus 3% without it (p = 0.034), though the adjusted association was not statistically significant (odds ratio 2.497, 95% CI 0.959 to 6.500, p = 0.061) (Kuriki et al., J Atheroscler Thromb, 2021) [6].
Study details are from PubMed abstracts.
Key Takeaways
An atrial septal aneurysm is a common, present-at-birth bulge of extra tissue in the wall between the heart's upper chambers. [1] [9]
Most people have no symptoms; the finding is often incidental on an echocardiogram. [1]
There are five types, classified by which way the bulge moves during the heartbeat cycle. [9]
The condition is associated with a higher risk of arrhythmias, blood clots, PFO, ASD, and stroke. [1] [2] [4]
Diagnosis requires a bulge of more than 10–15 mm beyond the atrial wall, seen on an echocardiogram. [9]
Treatment may include blood thinners, minimally invasive PFO closure, or rarely surgery — but many people need none. [9]
People with this condition appear to have a normal life expectancy. [9]
What Is Atrial Septal Aneurysm?
An atrial septal aneurysm is a congenital anomaly — meaning it is present at birth — of the heart. [9] When it is present, there is extra tissue in the wall (the septum) that separates the two upper chambers (atria) of your heart.
During your heart's pumping and relaxing cycle, this excess tissue sticks out into one or both upper chambers. [4] [7] Think of it like an extra piece of sailcloth in the wall between two rooms, billowing back and forth each time the wind (your heartbeat) moves through.
Experts also call it an interatrial septal aneurysm. In many cases, the aneurysm doesn't interfere with blood moving through your heart and doesn't require treatment. Estimates of how many people have this condition vary, but it is a relatively common finding. [1] [7]
What Are the Types of Atrial Septal Aneurysms?
Providers classify atrial septal aneurysms into five types based on which direction the bulging tissue moves as the heart beats. [9]
Type | Direction of the bulge |
1R | Sticks out into the right atrium |
2L | Sticks out into the left atrium |
3RL | Moves mostly toward the right atrium, but also a little toward the left |
4LR | Moves mostly toward the left atrium, but also a little toward the right |
5 | Moves both directions (right and left) equally |
What Are the Symptoms?
Atrial septal aneurysms are most often without symptoms. Providers frequently find them on a routine echocardiogram ordered for a completely different reason. [1]
If you do have symptoms, they may come from an associated finding — such as an arrhythmia, a blood clot, or a patent foramen ovale (PFO) — rather than from the aneurysm itself.
Symptom | What it may indicate |
Chest pain or discomfort | May signal an associated heart issue |
Heart palpitations | Often linked to an associated arrhythmia |
Dizziness | Can accompany rhythm changes or reduced blood flow |
Because the aneurysm is frequently discovered incidentally, many people go their whole lives without ever feeling anything unusual.
What Causes Atrial Septal Aneurysm?
Researchers don't fully understand what causes an interatrial septal aneurysm. Some researchers think genetics may play a role. Others believe a connective tissue flaw — a weakness in the tissue framework of the heart — may contribute. [9] What is clear is that the extra septal tissue is present from birth; [9] it is not something you develop later in life through lifestyle or habits.
What Are the Possible Complications?
An atrial septal aneurysm may be associated with an increased risk of several other heart-related issues. [1] [8] These are the reasons a provider may want to investigate further after the finding.
Associated risk | Description |
Stroke | Clots can form and travel to the brain |
Blood clots | Can form on or near the mobile bulging tissue |
Arrhythmias | Abnormal heart rhythms linked to the extra septal movement |
Patent foramen ovale (PFO) | An opening in the septum that didn't fully close after birth |
Atrial septal defect (ASD) | A hole in the wall between the upper chambers |
Other congenital heart issues | People with this condition often have additional heart conditions |
This is why providers often look for other heart problems once they find an atrial septal aneurysm — people with this condition frequently have other heart conditions as well. [1] [2]
How Is Atrial Septal Aneurysm Diagnosed?
A healthcare provider can use an echocardiogram to check for an atrial septal aneurysm. They may diagnose the condition if they see extra septal tissue that bulges more than 10 millimeters (some providers use a threshold of 15 mm) [2] [7] beyond the atrial wall. [9]
Often, people don't know they have the condition until they have an echocardiogram for another reason. Providers may also spot it in results from other heart imaging. [9]
Imaging test | How it works |
Transthoracic echocardiogram (TTE) | A device is moved across the skin on the left side of the chest; the standard first-line test |
Transesophageal echocardiogram (TEE) | A device is passed down the esophagus to show the whole atrial wall; finds aneurysms a TTE can miss |
Cardiac computed tomography (CT) | X-ray-based 3D imaging of the heart |
Heart MRI | Magnetic imaging that shows heart structure in fine detail |
Angiogram | A dye-based X-ray study of the heart's blood vessels |
Because people with this condition often have other heart issues too, your provider may want to check for related problems once the aneurysm is found.
How Is Atrial Septal Aneurysm Treated?
You may not need any treatment at all if you don't have other heart issues or risk factors for blood clots that could lead to a stroke. [9] When treatment is needed, it focuses on reducing stroke risk rather than on the bulge itself.
Treatment | When it's used |
No treatment (watchful observation) | No other heart issues or blood-clot/stroke risk factors |
Blood thinners (anticoagulants or antiplatelets) | For people with the condition who can develop blood clots |
Patent foramen ovale (PFO) closure | A minimally invasive procedure that can reduce stroke risk; antiplatelets may be needed afterward for a few months or even for life (if you have a stroke history) |
Surgical removal | Rarely needed; reserved for exceptional cases |
After a PFO closure or surgery, your provider will want to see you for regular follow-up appointments, [9] which may include repeat imaging tests.
How Serious Is an Atrial Septal Aneurysm?
An atrial septal aneurysm in itself isn't a cause for concern. But if you have other factors that put you at risk for stroke, you need to take it seriously. [9] The aneurysm alone rarely causes problems; it's the combination with blood clots, a PFO, or an arrhythmia that changes the picture.
Your provider will weigh your complete heart-health profile — not just the aneurysm — when deciding whether you need medication, a procedure, or simply periodic monitoring.
What Is the Outlook (Prognosis)?
People with an atrial septal aneurysm appear to have a normal life expectancy. [9] Of course, every situation is different — you may have other medical issues that affect your life expectancy.
A diagnosis may take you by surprise, especially if you have no symptoms. In many cases, it isn't a cause for worry. But if the finding puts you at a higher risk of stroke, talk with your healthcare provider about a plan to protect yourself. For extra peace of mind, teach your loved ones and co-workers the warning signs of stroke — knowing the signs may help you or someone else in the future.
When should I go to the ER?
Get immediate medical attention if you or someone you're with has stroke symptoms. [9]
Stroke warning sign | What to watch for |
Trouble speaking | Slurred words or inability to form sentences |
Weakness on one side | Arm, leg, or face drooping on one side of the body |
Dizziness | Sudden unsteadiness or loss of balance |
Blurry vision | Sudden changes in eyesight |
Sudden loss of a sense | One or more senses disappearing without warning |
Confusion | Disorientation or trouble understanding |
Severe headache | A sudden, unusually intense headache |
How Do I Take Care of Myself?
If your provider prescribes medicine to help prevent a stroke, it's important to take it for as long as they tell you — and in the amount they recommend. Don't stop taking medicine without talking to your provider first.
If you've had a procedure or surgery, keep all follow-up appointments, which may include repeat imaging tests to confirm everything remains stable.
What questions should I ask my doctor?
Do I need treatment for my atrial septal aneurysm?
How often do I need follow-up appointments with you?
Do I have other heart issues in addition to an atrial septal aneurysm?
What's the outlook for my specific situation?
Conclusion
An atrial septal aneurysm is a common, usually harmless finding — an extra flap of tissue in the wall between the heart's upper chambers that most people never feel. By itself it rarely causes problems, and people with the condition appear to have a normal life expectancy. [9] The finding matters most when it arrives with company: blood clots, a patent foramen ovale, or an arrhythmia that can raise stroke risk. [1] [4] In those cases, modern medicine has clear tools — blood thinners, minimally invasive PFO closure, and occasionally surgery — to keep the risk low. [9] If you've been told you have a septal aneurysm, the smartest next step is a full conversation with your healthcare provider about your personal risk profile.
Next step: If an echocardiogram has shown an atrial septal aneurysm, ask your provider whether additional screening for blood clots or a PFO makes sense for you. Want to share these insights with family or your practice? Turn them into a clear, shareable infographic using the free infographic templates at Rinnit and create health visuals in minutes.
FAQ
What exactly is an atrial septal aneurysm?
An atrial septal aneurysm is a common birth-related anomaly in which extra tissue in the wall (septum) between the heart's two upper chambers bulges outward into one or both atria as the heart pumps and relaxes.
Is an atrial septal aneurysm the same as a brain aneurysm?
No. A brain aneurysm is a bulge in a blood vessel in the brain, while an atrial septal aneurysm is extra tissue in the heart's dividing wall. The two are unrelated, though both are called aneurysms because of the bulging shape.
Is it dangerous?
By itself, no — the condition isn't a cause for concern on its own. It becomes important when you also have stroke risk factors such as blood clots or a patent foramen ovale (PFO). [1]
How common is it?
An atrial septal aneurysm is relatively common. [1] [7] Estimates of how many people have it vary, and most who do never know — it is often found by chance on an echocardiogram ordered for another reason. [1]
What are the five types?
Providers classify the bulge by direction: 1R (into the right atrium), 2L (into the left atrium), 3RL (mostly right, a little left), 4LR (mostly left, a little right), and 5 (both directions equally). [9]
What causes it?
Researchers don't fully understand the cause. Some think genetics or a connective tissue flaw may play a role. It is present from birth. [9]
Can it be seen on any imaging test?
Yes. A standard transthoracic echocardiogram (TTE) often reveals it, but a transesophageal echocardiogram (TEE) shows the whole atrial wall and can find aneurysms a TTE misses. Cardiac CT, heart MRI, and angiograms may also detect it. [9]
How big must the bulge be for diagnosis?
Providers diagnose an atrial septal aneurysm when extra septal tissue bulges more than 10 millimeters beyond the atrial wall (some use a threshold of 15 mm). [9]
Do I always need treatment?
No. If you have no other heart issues or blood-clot/stroke risk factors, you may need no treatment at all. [9]
What treatment options exist?
Blood-thinning medications (anticoagulants or antiplatelets) for clot risk, minimally invasive PFO closure to lower stroke risk, and — rarely — surgical removal of the aneurysm. [9]
Will I need medication forever?
After a PFO closure, you may need antiplatelets for a few months or even for life if you have a stroke history. [9] Your provider will set the duration based on your individual risk.
Does it affect life expectancy?
People with an atrial septal aneurysm appear to have a normal life expectancy. [9] Other medical issues you carry can also influence the outlook.
Should I teach my family the stroke warning signs?
Yes — that is recommended. Knowing the signs of stroke (trouble speaking, one-sided weakness, sudden confusion, severe headache, vision changes) may help you or someone else respond quickly.
Can it be caught before birth?
Yes. Fetal atrial septal aneurysms can be followed from the second to the third trimester, and providers may discuss implications after birth. [3]
References
Cho K, Feneley M, Holloway C. Atrial septal aneurysms: a clinically relevant enigma? Heart Lung Circ. 2022;31(1):17-24. PMID 34507890. https://doi.org/10.1016/j.hlc.2021.07.025
Giannopoulos A, Gavras C, Sarioglou S, et al. Atrial septal aneurysms in childhood: prevalence, classification, and concurrent abnormalities. Cardiol Young. 2014;24(3):453-458. PMID 23742845. https://doi.org/10.1017/S1047951113000607
Gireadă R, Ursache A, Matasariu R, Socolov R. Fetal atrial septal aneurysm: follow-up from second to third trimester. Diagnostics (Basel). 2022;12(6):1469. PMID 35741279. https://doi.org/10.3390/diagnostics12061469
Imburgio S, Wiseman K, Udongwo N, et al. Atrial septal aneurysm: an incidental finding or a clinically significant anomaly? Cureus. 2022;14(9):e29557. PMID 36312631. https://doi.org/10.7759/cureus.29557
Kumagai M, Nishizawa J, Takehara M, et al. Surgical management of a giant atrial septal aneurysm. Clin Case Rep. 2021;9(5):e04125. PMID 34026164. https://doi.org/10.1002/ccr3.4125
Kuriki A, Ueno Y, Kamiya Y, et al. Atrial septal aneurysm may cause in-hospital recurrence of cryptogenic stroke. J Atheroscler Thromb. 2021;28(5):514-523. PMID 32684557. https://doi.org/10.5551/jat.56440
Yetkin E, Atalay H, Ileri M. Atrial septal aneurysm: prevalence and covariates in adults. Int J Cardiol. 2016;223:656-659. PMID 27567234. https://doi.org/10.1016/j.ijcard.2016.08.220
Yetkin E, Ileri M, Korkmaz A, Ozturk S. Association between atrial septal aneurysm and arrhythmias. Scand Cardiovasc J. 2020;54(3):169-173. PMID 31544553. https://doi.org/10.1080/14017431.2019.1667525
Cleveland Clinic. Atrial Septal Aneurysm: Symptoms and Treatment. Cleveland Clinic Health Library. Last updated January 30, 2024. https://my.clevelandclinic.org/health/diseases/atrial-septal-aneurysm
Related Reading
Disclaimer: This article is for general informational purposes only and is not medical advice. Always consult a qualified healthcare provider for diagnosis and treatment decisions tailored to your situation.
Medical disclaimer
The information provided in this article is for educational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
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