The surgical anatomy of the aortic root - Multimedia Manual Cardio ...

R.H. Anderson / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2006.002527
Photo 8. This dissection has been made first by removing the freestanding
subpulmonary infundibulum, and then by removing the triangle
between the two coronary aortic sinuses. As can be seen,
the tip of the triangle ‘points’ to the tissue plane between the back
of the infundibulum and the aortic root.
valvar components. The supravalvar components, the
aortic sinuses, are primarily aortic in structure, but
contain structures of ventricular origin at their base.
The supporting subvalvar parts are primarily ventricular,
but extend as thin-walled fibrous triangles to the
level of the sinutubular junction. The sinutubular junction
itself forms the discrete distal boundary of the
root. The valvar leaflets are attached peripherally at
this level, and hence, the junction is an integral part
of the valvar mechanism. Any significant dilation at the
level of the sinutubular junction will produce valvar
incompetence. It is moot, therefore, whether stenosis
at this level should be labelled as ‘supraaortic’, since
the sinutubular junction is just as crucial a component
of the overall valvar mechanism as are the leaflets and
their supporting sinuses w8x. Anatomically, the sinutubular
junction is no more than the distal extent of
the overall valvar complex.
Is there a valvar annulus?
The answer to this question, the major ongoing
conundrum for the cardiac surgeon, depends very
much on the structure nominated to represent the
‘annulus’. If we take refuge in the dictionary, and seek
etymological origins, then we find that an annulus is
no more than a little ring. In this regard, it is certainly
the case that the entirety of the aortic root can be
removed from the heart, and can be slipped on the
finger in the form of a ring. As far as I am aware,
however, no surgeon defines the entirety of the root
as the aortic valvar annulus. Most surgeons seem to
nominate the remnants of the removed valvar leaflets
as their annulus w3, 9x. As I have described, however,
by virtue of their semilunar position, these structures
are supported in crown-like fashion when viewed in
the three-dimensional context of the overall aortic root
(Schematic 2). Other surgeons, in contrast, define the
virtual basal ring constructed by joining together the
most proximal parts of each leaflet as the ‘annulus’
w2x. It is certainly this diameter that is typically analysed
by the echocardiographer when providing
measurements of the diameter of the purported structure
(Schematic 3).
In view of these ongoing discrepancies, it is my own
belief that the aortic root would be best understood if
divorced from the concept of the ‘annulus’. This is
unlikely to happen. We need to understand, therefore,
that the aortic root itself is cylindrical, with the valvar
leaflets supported within the root in crown-like, rather
than circular, fashion (Schematic 2). We should also
take note that there can be marked differences in
diameter of its component parts, not only in the nor-
Schematic 2. The cartoon shows an idealised aortic root. The
attachments of the valvar leaflets, shown in red, extend through the
entire length of the root, from the sinutubular junction, in blue, to
the virtual basal ring, shown in green, and produced by joining
together the basal attachments of the leaflets. The crown-like
attachments of the leaflets cross the anatomic ventriculo-aortic
junction, shown in yellow.
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