Atrial Septal Defects

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Atrial septal defects, or a hole between the two atrium are among the most common of congenital heart defects and the most easily repairable of all defects. This defect s one of the most common reasons that an echocardiographer will image a neonate, as well as looking for a PDA, or patent foramen ovale (a hole between the aorta and pulmonary artery).

(Please see my posts on embryology). These two defects are naturally occurring holes that every neonate is born with. Since the fetus obtains most of their nutrients and oxygenated blood flow through the arterial and venous connections via the placenta and the mother, these defects are necessary to deliver blood flow that is destined for the lungs in the fetus, to the left ventricular circulation. In other words, the fetus does not breathe, therefore, blood flow to the lungs is not necessary.

Once born and the neonate begins to breathe, and these two holes should close naturally providing the neonate is of full gestation ( 40 weeks). Closure usually happens with in a few days. If the neonate is premature, closure tends to persist until the neonate reaches 40 weeks. The body seem to be programmed to this 40 week schedule.

In the neonate with persistent opening of these defects, blood will flow left-to-right across the defect and create a volume overload of the right heart, and thus the lungs. This tends to create a situation in which there is diminished oxygen transfer between the lungs and the capillary beds that supply oxygen rich blood to the rest of the body.

About one in ten neonates with any other congenital heart defect will have an atrial septal defect, and surprisingly, autopsy results indicate that up to one of every three adults may have an open PFO. The foramen ovale tends to be a defect that can be passive, in other words it will open when there tends to be a pressure difference between the right and left atriums.

Under normal circumstances, the pressure in the left and right atriums tend to be equal, approximately 5-10 mmHg. In the presence of other cardiac defects, such as a valsalva maneuver, CHF, or any other defect that may compromise flow, the defect may temporarily open.

It has been my experience that many young adults who suffer a stroke, often have a temporarily open PFO. This is often revealed while doing a TEE, or trans-esophageal echocardiogram. This means that for whatever reason, a blood clot that has developed in the venous system, passed through the PFO, entered the arterial blood flow, and progressed to the brain to cause a stroke.

There are typically three types of atrial septal defects:

Sinus Venosis Defects:
This defect occurs at the roof of the atrium, and may allow one or more of the left pulmonary veins to drain directly into the right atrium. The inter-atrial septum for the most part  is a muscular structure at it’s base and roof, while the foramen tends to be flexible structure that may or not be patent. Coronary sinus defects occur also at this level. This means that the coronary sinus, the venous return from the coronary veins, drains into this structure.

Primum ASD, or Ostium Primum Defect:
This defect occurs at the inferior portion of the inter-atrial septum and is highly associated with AV canal defects, or endocardial cushion defects (see my posts on this subjects). This defect tends to happen when the crux of the heart fails to fully develop. The AV valves do not fully form as well as the inferior portions of the atrial septum, and the superior portions of the interventricular septum fail to completely attach appropriately.

Patent Foramen Ovale or PFO:
As stated before, this opening between the atriums is a common occurrence in neonates as well as adults.  The most common presentation physiologically in this person would be dyspnea upon exertion. This defect is typically asymptomatic and may never be discovered even into adulthood, unless there is some other symptom that develops, such as a stroke in a young adult.

Echocardiography:
Contrast echocardiography, or TEE with contrast is the best way to evaluate this defect. This defect can often be found with echocardiography alone, but it is not the most accurate way to evaluate this defect, since this defect may occur spontaneously, e.g. with respiratory or with valsalva maneuvers.

Always evaluate the interatrial septum in multiple views. These defects are not typically heard with a stethoscope or with physical examination, and X-ray evaluation may be non-specific, or at best show an enlarged right heart.

Always rule out a sinus venosis defect by evaluating the pulmonary venous inflow, and rule out a primum defect by evaluating for an AV canal (or endocardial cushion defect).

Prognosis and Repair
These types of defects are well tolerated and may never present symptoms. Right ventricular overload is usually well tolerated by the body, and pulmonary hypertension typically occurs late in adulthood. Unless the shunt is large, symptoms tend to be minimal throughout adulthood. A CVA, or a stroke in a younger patient is often the only way that these defects may be found.

Spontaneous closure of these simple shunts often occurs during adolescence. Very often, VSD’s, ASD’s and PFO’s are often followed until this time, unless the patient begins to exhibit right ventricular enlargement, pulmonary hypertension or congestive heart failure, or chronic respiratory problems.

If repair is needed, it typically involves the placement of a “rivet” type of device that closes the PFO that is minimally invasive, or a surgical procedure that sutures the shunt closed (primum or venosis types of shunts). Mortality and complications are extremely low for all of these procedures.

Long term results are excellent, and complications are rare.

26 responses to “Atrial Septal Defects”

    1. These things are well covered in my book. These blogs provide additional information. In a normal heart, both sides pump the same volume. It is simple physics. What goes in, goes out. In a preemie, pulmonary hypertension it Is not abnormal, in fact it is typical.

      In ASD or VSD defects, there there is certainly volume overload. This reduces oxygen transfer in the capillary bed of the lungs.

  3. A lot of people like books, especially echo techs who take it with them to the ICU. Of course, the day will come when everyone will just take their tablet to the ICU, and we have offered a PDF for a long time which looks great on a tablet.

    Someday, books will be obsolete, but not quite yet.

    Thanks for your post

    Ken Heiden

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    1. First, if you really dig, you will be amaezd how little evidence exists to support many of the things we MDs do. However, it can be difficult to get patients into randomized trials when something as emotionally charged as stroke risk is involved. I hope that the RESPECT trial can get sufficient power to answer the damn question.I think the Amplatzer is eponymous, but, hey, you can google that as well as I can.Finally, although I am now specialized in that magnificent organ, the kidney, I did go through pediatric residency and learn all about innocent murmurs. A murmur is merely doctor-speak for an extra heart noise. Instead of the normal lub-dub we hear an extra whoosh or buzz or hum. Several of these are often heard in children who have smaller chests than adults. As kids grow, these noises are no longer heard because the normal structure causing it is farther away from the stethoscope or other hemodynamic changes have ensued. A true innocent heart murmur would not require antibiotics for dental care (as prophylaxis for subacute bacterial endocarditis); that should be reserved for structural abnormalities on which an infection is likely to occur, not a structurally normal heart. A PFO is often clinically silent- it yields no murmur or other clue it is there until you do the echocardiogram. Last time I checked it was not on the SBE risk list, either.

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    1. Hi Melissa;Your story is so amazingly silamir to mine. I appreciate you taking the time to share the details of your journey especially the time line on how you arrived at being able to close your PFO. Many individuals have called me off the record after reading my story and were told their best possible option for closure was to enroll in a silamir study to the one you mentioned. The general feeling is that these individuals do not want to enroll because they want to get their heart defect repaired and not have to live with Not knowing . It is to that end that I stay motivated to help advance the education and recognition /screening for PFO/ASD. Each time I hear a story like yours my commitment is strengthened. Thank you. EVERY time I hear of a case where the results were not so good, like the examples you shared, I get angry that perhaps more could be done.I just learned a short while ago of a high school boy in my area that went into his basement to lift weight and later was found dead. It was determined the cause of death was he had an undiagnosed PFO. I know that could have been me. and that is why I feel the most compelling point you shared in your story is when you described feeling blessed and fortunate and having the small signs that alerted you something was not right. Those signs and your outcome happened for a reason, in my opinion, as they did in my case. I hope I can count on you to help with this cause in the future. For now, sharing your story was a big help. Best wishes in your recovery, David

      1. if you’re young and having these symptoms, I would get an echo and check for a PFO

      2. good idea to listen to your cardiologist and get it repaired. It is a simple procedure in and out the same day. It is much better than having a stroke.

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    1. Thank you so much, I really appreciate your input. Go to heartdefectssimplified.com, or go to pediatric echo sonographers on Facebook and join our little society.

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    1. that I have complained with heceaahds since age 5.At age 51 I had a hysterectomy. Seven days later I had a stroke. After test I was told that they found I had a PFO that allowed a blood clot from my surgery to my brain.My Cardiologist said I should get it repaired but after seeing 3 other cardiologist in Houston,Texas I was told there was an FDA hold on the surgery, but that I could be in a study The Star-flex closure study . I was randomized to the take medication part (coumidan). After 3 years I am told the study still has at least another year or 2 till completion. They say no surgeries are being preformed at this time.But I heard that Bret Michaels is going to have the surgery, Is that because he is famous or are my doctors misinformed. I am so confused

      1. This procedure is done routinely and only involves a catheterization. They pass the catheter up to your heart, and then they essentially put a rivet between the two atria.

        I cannot tell you how many times I’ve seen strokes in young people who have a PFO. Is a congenital heart defect that you have had since birth. It is unusual from blood clot to pass through the PFO, but when it does I suggest that you listen your cardiologist.

      3. I would strongly suggest getting it repaired. I cannot tell you how many strokes I’ve seen in young people as a result of a PFO. It is a simple procedure, same-day and Same day out.

      4. I have seen so many strokes in young people with PFO’s. Listen to your cardiologist and get repaired

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