Sunday, March 1, 2015

The Aortic Valve - What Can Leaflets Tell Us?

Da Vinci's sketch of the aortic valve, including BAV
Five Hundred Years Ago

About 500 years ago, Leonardo da Vinci studied human anatomy. From his access to animals and also human cadavers, he explored the mysteries of life through the dead. Outstanding still today among his amazing work are his studies of the heart and its valves, including a sketch of aortic valves with abnormal leaflets, including those with only two leaflets (bicuspid) and four leaflets (quadricuspid). 

This aortic valve was consistently called a normal three
leaflet valve when viewed by echocardiogram. After removal,
it is clear that two of the leaflets are fused. The man born with
this valve had no reason to think about his health or his heart
until the day searing pain dropped him to the ground.
His aorta had dissected.  Picture courtesy of Dr. Sharo Raissi
Where We Are Today

Despite technology that shows us inside the living beating heart today, we still struggle to clearly and accurately "see" the aortic valve during life and to understand what it means.

Why is it so important to see clearly? The entire picture is needed to help someone. Abnormal aortic valves are associated with other problems, including infection (endocarditis), abnormal aortic tissue, aneurysm. and dissection.

The valve pictured here was consistently read as trileaflet by echocardiography. Only when it was removed did the fusion between two leaflets reveal itself to the world. An aortic valve with three leaflets is said to have a triangular opening, a bicuspid valve to have an oval opening. This valve has a triangular opening, although there is fusion of two of the leaflets. Someone with a valve like this may have an echo at some point in life,  be told their valve is normal, and never be monitored for the development of an aortic aneurysm.  They are vulnerable to an aortic emergency, like the dissection that struck the man whose valve we see here.

The Importance of Leaflets

The Bicuspid Aortic Foundation uses wording like "apparently normal" or "appear to be normal" to describe aortic valves with three leaflets in the presence of aortic aneurysm and dissection or rupture. This is because we know that there may be something wrong with these seemingly normal aortic valves and their leaflets. It is just more subtle. Bicuspid aortic valves have been associated with aortic aneurysm and dissection for a very long time. What about those three leaflet aortic valves out there? It is not possible to take a snippet of tissue and study it, but is there a way to find slight abnormalities through imaging tests?

Warning for BAV Families in 2007

In 2007, I read about 13 families in this paper, Familial thoracic aortic dilation and bicommissural aortic valve: a prospective analysis of natural history and inheritance. These families all had at least one person with a BAV. But there were others in these families who appeared to have normal aortic valves with all three leaflets, yet they still had an aneurysm. Some of them dissected and died. I knew it was important to tell BAV families about this, to help save the lives of everyone in the family. From that time, it was clear that just checking the aortic valve was not enough to keep family members safe. But the question has remained, are these apparently normal trileaflet valves really normal, or just part of a continuum of BAV?

It's 2015, and Dr. Sperling's Paper Sheds New Light

The recently published work of Dr. Jason Sperling, a member of the BAF Scientific Advisory Board, has shed new light on aortic valve abnormalities in this paper: "Forme fruste or ‘Incomplete’ bicuspid aortic valves with very smallraphes: The prevalence of bicuspid valve and its significance may be underestimated".  Pictured in this paper are aortic valves with very slight fusion of the leaflets, in the "corners" where they come together. These are aortic valves whose abnormalities are so slight they are easily missed. Dr. Sperling's work shows how these slight abnormalities may be found through imaging.

There is no doubt that the more we understand about the mysteries of the aortic valve, we also understand more about the big picture of aortic disease in our bodies.

Thank you so much, Dr. Jason Sperling,
 for your careful attention to detail and 
your dedication to unlocking
 the mysteries of the aortic valve.

You are creating a climate of hope
for patients everywhere.

- Arlys Velebir
                           BAF President and Chairman