Anatomy of the aortic root with particular emphasis on options for its surgical enlargement.

BACKGROUND AND AIMS OF THE STUDY

The aortic root is a frequent site of surgical intervention, both in adults and children, yet there is ambiguity about the precise nature and relation of the various structures composing the aortic root. The present review aims to clarify these ambiguities and to explain the morphological basis of surgical procedures for enlargement of the aortic root.

MATERIALS AND METHODS

Using autopsied specimens of normal hearts, the morphology of the attachment of the leaflets, the interleaflet triangles and the circular ventriculo-arterial junction of the aortic root were studied in detail, paying special regard to fibrous and muscular continuity, relation to the atrioventricular conduction axis, and the coronary arterial branching. Surgical dissections and incisions required for enlargement of the aortic root were simulated in these specimens.

RESULTS

It was evident that the locus of attachment of aortic valvar leaflets takes the form of three (semilunar) crescents. This attachment is not circular, as the word 'annulus' suggests, neither does it correspond to the anatomical ventriculo-arterial junction. During implantation of a mechanical valve in the aortic position, a circular prosthetic valve ring is sutured on to the attachments of the native valvar leaflets. This must entail some distortion when the sutures are tied. Analysis of autopsied specimens showed that, on completion of the process of suturing, the location of the prosthetic valve is close to the anatomic ventriculo-arterial junction-one of the true annular regions of the aortic root.

CONCLUSIONS

The continuity of the aortic valvar leaflets and the interleaflet triangles with structures such as the aortic (anterior) leaflet of the mitral valve posteriorly, and with the muscular ventricular septum anteriorly, provide an opportunity for surgeons to enlarge the aortic root by widening of the anatomic ventriculo-arterial junction.