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

R.H. Anderson / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2006.002527
Schematic 1. The cartoon shows a bisected aortic root, and illustrates
how the semilunar attachment of the valvar leaflets incorporates
aortic wall in the intersinusal triangles, and ventricular tissues
at the base of each of the coronary aortic sinuses.
attachments at the sinutubular junction (Photo 3). The
root as thus defined, therefore, is a cylinder, its walls
being made up of the aortic valvar sinuses along with
the interdigitating intersinusal fibrous triangles, and
with two small crescents of ventricular muscle incorporated
at its proximal end (Schematic 1).
It is the semilunar attachments of the leaflets within
the valvar sinuses that form the haemodynamic junction
between the left ventricle and the aorta. All structures
on the distal side of these attachments are
subject to arterial pressures, whereas all parts proximal
to the attachments are subjected to ventricular
pressures. In functional terms, all three sinuses of the
root, and their contained leaflets, are identical. Anatomically,
however, it is necessary to distinguish
between the three components. This is best achieved
by noting that two of the valvar sinuses give rise to
the coronary arteries (Photo 4). These can be nominated
as the right and left coronary aortic sinuses.
These two sinuses, for their greater part, are made up
of the aortic wall. But, because the semilunar attachments
of the leaflets cross the anatomic ventriculoaortic
junction, a crescent of ventricular musculature
is incorporated at the base of each of these two sinuses
(Photo 3, Schematic 1). The third sinus does not
give rise to a coronary artery, and hence, can be designated
as the non-coronary aortic sinus. There is no
muscular crescent at the base of this sinus, since this
sinus has exclusively fibrous walls, the basal part
beneath the anatomic ventriculo-aortic junction being
part of the important continuity between the leaflets
of the aortic and mitral valves that is a feature of the
outflow tract of the left ventricle (Photo 5).
The areas between the basal attachments of the aortic
sinuses within the ventricle itself, which extend distally
to the level of the sinutubular junction, are
triangular extensions of the left ventricular outflow
tract. They are thinned fibrous areas of the aortic wall.
Photo 4. The heart has been dissected by removing the atrial chambers
and the arterial trunks, and is photographed from above, looking
down on the atrioventricular and ventriculo-arterial junctions. It
is orientated as it may be seen by the surgeon. The dissection
shows how two of the aortic valvar sinuses (1, 2) give rise to
coronary arteries, and can be nominated as the left and right coronary
aortic sinuses, respectively. The third sinus (3) does not give
rise to a coronary artery, and hence, is the non-coronary aortic
sinus. Note again that the aortic valve forms the cardiac
centrepiece.
Photo 5. The aortic root has been opened from the front, and the
leaflets of the aortic valve removed. The dissection shows how the
interleaflet triangle between the non-coronary and left coronary aortic
sinuses (purple dashed line) is part of the area of fibrous continuity
with the aortic leaflet of the mitral valve. The red dotted line
marks the anatomic ventriculo-aortic junction.
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