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

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R.H. Anderson / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2006.002527
Photo 1. This section through the heart, replicating the parasternal
long axis echocardiographic cut, shows how the aortic root is the
centrepiece of the heart. The root extends from the basal attachments
of the valvar leaflets within the ventricle (yellow arrows) to
the sinutubular junction (red dotted line). The compass shows the
orientation relative to the remaining thoracic organs.
aortic root as seen by the anatomist, albeit with some
illustrations orientated to match the views obtained by
the surgeon. My emphasis will be on the semilunar
attachments of the aortic valvar leaflets, and their relationships
to the aorta and its ventricular support w5–
7x. In their own contribution to the Manual, Lausberg
and Schäfers w4x rightly emphasise the importance of
the aorto-ventricular junction. They fail, however, to
tell the reader whether they refer to the junction
between the left ventricular structures and the aortic
valvar sinuses, this representing the anatomic junction,
or the semilunar lines of attachment of the
arterial valvar leaflets, this locus representing the haemodynamic
ventriculo-arterial junction. As I have
shown previously w5x, it is recognition of the distinction
between these two junctions that is the key to
understanding.
What is the aortic root?
The aortic root, representing the outflow tract from the
left ventricle, provides the supporting structures for
the leaflets of the aortic valve, and forms the bridge
between the left ventricle and the ascending aorta.
The root itself, surrounding and supporting the leaflets,
has length in that it extends from the basal
attachments of the leaflets within the left ventricle to
the sinutubular junction (Photo 2). The discrete anatomic
ventriculo-aortic junction is a circular locus
within this root, formed where the supporting ventricular
structures give way to the fibro-elastic walls of
the aortic valvar sinuses. This discrete ring, however,
is markedly discordant with the morphology of the
attachment of the leaflets of the aortic valve. Indeed,
Photo 2. This close-up of the section illustrated in Photo 1 shows
the extent of the aortic root, and reveals the semilunar attachments
of the valvar leaflets supported by the right coronary and non-coronary
aortic valvar sinuses. The red dotted line again shows the
sinutubular junction, which is the distal extent of the root, whilst the
red arrow shows the basal attachment of the right coronary aortic
valvar leaflet, marking the proximal extent of the root. As shown by
the yellow arrow, the anatomic ventriculo-aortic junction is in the
middle part of the root, and is crossed by the hinge-lines of the
valvar leaflets (see Photo 3).
it is crossed at several points by the hingelines of the
valvar leaflets. These lines, semilunar in structure,
extend throughout the root, running from their basal
attachments within the left ventricle to their distal
Photo 3. The aortic root has been opened from behind and spread
apart, so that the full width of the cylinder can be seen. The aortic
valvar leaflets have then been removed, revealing the semilunar
nature of their attachments. The purple dotted line shows the anatomic
ventriculo-aortic junction, which is the union between the
ventricular musculature and the aortic wall at the bases of the left
and right coronary aortic valvar sinuses (1, 2), but between the
aortic wall and fibrous continuity with the mitral valve at the base
of the non-coronary sinus (3). Note how the semilunar attachments
incorporate muscle at the base of the coronary aortic sinuses,
but fibrous tissue within the ventricle as the hingelines extend
distally to reach the sinutubular junction (red dashed triangle).