Valley Heart & Vascular Institute - Bicuspid Aortic Valve (BAV)
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Bicuspid Aortic Valve

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Bicuspid Aortic Valve (BAV) is the most common congenital (birth) heart defect, present in up to 1 in 50 people in the United States population. ‘Normal’ aortic valves have three leaflets and three aortic sinuses (aortic root bulges joined to the aortic valve leaflets).

BAV patients either have two semi-lunar shaped aortic valve leaflets with two aortic sinuses, but much more commonly (almost 90% of the time) there are three leaflets but two are at least partially fused, and usually there are three sinuses. This more common anatomic appearance can make diagnosis difficult, because with three sinuses and only partial fusion, these look very much like ‘normal’ tri-leaflet valves, but the problem is not what they look like, it is what this finding represents.

BAV is a syndrome of abnormal embryology. There is a common origin of embryologic cells (specifically, a cell source call the neural crest mesenchyme) that migrate to help form this exhaustive list of cardiovascular structures: the aortic valve and root, coronary artery origins, pulmonic valve and root, ascending aorta and aortic arch extending to the ligametum arteriosum. The genetic defect in these cells results in decreased production of an important extracellular matrix protein called fibrillin, which leads to certain imbalances that may lead to mechanically weaker tissue, which in the case of the aorta, can lead to aneurysm and rupture.

Interestingly, a syndrome well known to be associated with the most brittle aneurysms (the Marfan syndrome) has genetic deletion of the fibrillin-1 gene, leading to absence of fibrillin completely in those patients. What this means is that when BAV is present, smaller aneurysms may be weaker than even usual, and intervention has now been suggested at smaller sizes based on something called relative aortic size in order to prevent complications. Regarding the valve itself, it is a fallacy that all BAVs eventually fail and require replacement.

Approximately 60% of patients with normally functioning BAVs (at the time of diagnosis) have valves that continue to function normally throughout life (elderly patients up to 89 years of age have been documented to have perfectly functional BAV valves). Unfortunately, the remaining 40% will likely suffer an adverse medical event related to the BAV, and 1/3 will need some form of surgery along a 20 year follow up period, according to a recent Mayo Clinic publication.

Click here to see a BAV Repair performed at The Valley Hospital.

According to the NIH-funded Gen-TAC Registry (click here for full article), patients with BAV had an average age at first surgery of 43 years old. Consequently, patients who required aortic valve replacement at ages younger than 65 are much more likely to have had BAV that was either identified in the OR, or missed due to its similar appearance to normal tri-leaflet valves, especially when stenotic (blocked up with calcium and cholesterol). These patients should maintain good follow up with their cardiologists who will need to perform periodic echocardiograms (cardiac ultrasound) in order to detect the development of significant valvular disease and/or aortic aneurysm over time.

BAV Disease typically runs in families, with an estimated 1 in 3 first-degree relatives of a BAV patient inheriting either the BAV itself or a propensity towards forming aneurysm (‘aortopathy’). Because of how important it now seems to correctly diagnose BAV, we have developed unique and sophisticated imaging that allows us to make the diagnosis of BAV using special CT scanning techniques and software. This will be particularly useful in patients with equivocal diagnosis of BAV by echo, and we hope to publish on this in the coming years. BAV patients are followed in our TABAV Registry longitudinally to detect changes in valvular and aneurysm behavior that may dictate the need for a pre-emptive intervention to prevent an adverse medical event.

For more information, please call Ellen Oehrlein, RN, BSN-BC, at 201-447-8398 or e-mail eoehrle@valleyhealth.com.

 
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