The normal closure mechanism is designed so that all
3 leaflets simultaneously meet, or coapt, in the middle of the flow channel.
Once the valve is closed, blood is prevented from falling backwards into the
pumping chamber below. The photograph on the right shows a normal
human aortic valve (as seen from above the heart).
The valve is nearly
closed, with the 3 leaflets meeting in the middle of the flow channel.
The crucial nutrient arteries to the heart muscle (the coronary arteries) arise from the wall of the aorta just above the aortic valve. These small 3 mm blood vessels are critical to survival. No such arteries arise from the corresponding location near the pulmonary valve. One of the key surgical challenges during transfer of the pulmonary valve to the aortic position is the successful reimplantation of the coronary arteries into the autograft. In The Learning Center presentation on the surgical technique, you can see how the surgeon must deal with the coronary arteries during the autotransplant procedure.
The leaflets of both semilunar (i.e. the aortic
and pulmonic) valves are attached at their
bases to a scalloped ring of tough, dense
fibrous tissue at the base of the heart. This ring
of fibrous tissue is called the valve annulus.
The crest of each leaflet is attached to the wall
of the encompassing blood vessel. For the
aortic valve, the attachment takes place a
centimeter or so above the annulus directly into
the walls of the aorta. Similar attachment points
are seen in the wall of the pulmonary artery for
the 3 leaflets of the pulmonic valve. The location where two leaflets come
together at a juncture point is called a commissure. The tri-leaflet semilunar
valves (i.e. aortic and pulmonic valves) both have 3 leaflets and 3
commissures.
The main anatomic feature that makes the Ross operation so attractive is
the identical physical structure of the two valves. Normal aortic and
pulmonic valves are both identical is size, shape and configuration. Both are
trileaflet valves with the same semilunar configuration as seen in these
photographs. Even when the aortic valve is deformed, the pulmonary valve
is almost always created as nature intended. Thus the pulmonary valve
provides the closest identical twin possible for the aortic valve. In
addition, the pulmonary valve is within a millimeter or two of being the exact
right size, is always sterile, and is comprised of living tissue. Since the
autograft comes from the same individual, rejection is never a concern. For
more on the advantages of using the autograft for aortic valve surgery,
please visit to the sections on Patient Selection and the Pros and Cons of
the Ross procedure.
