**5. Surgical anatomy**

A thorough knowledge of the anatomy of the aortic valve and its relations to the surround‐ ing cardiac structures is a prerequisite for the successful completion of the repair or replace‐ ment performed by the surgeon.

Surgical descriptions of the aortic root are not always similar with the anatomical descrip‐ tions, leading to a series of confusional data. Also the in vivo measurement of the valve components don't always correspond to the ex vivo measurements, in part due to the move‐ ment of the heart and its structures during the cardiac cycle.

By sequentially following the line of attachment of each leaflet, the relationship of the aortic valve to its surrounding structures can be clearly understood. Beginning posterior‐ ly, the commissure between the noncoronary and left coronary leaflets is positioned along the area of aorto-mitral valvular continuity. The fibrous subaortic curtain is be‐ neath this commissure. To the right of this commissure, the noncoronary leaflet is attach‐ ed above the posterior diverticulum of the left ventricular outflow tract. Here the valve is related to the right atrial wall. As the attachment of the noncoronary leaflet ascends from its nadir toward the commissure between the noncoronary and right coronary leaf‐ lets, the line of attachment is directly above the portion of the atrial septum containing the atrioventricular node. The commissure between the noncoronary and right coronary leaflets is located directly above the penetrating atrioventricular bundle and the membra‐ nous ventricular septum. The attachment of the right coronary leaflet then descends across the central fibrous body before ascending to the commissure between the right and left coronary leaflets. Immediately beneath this commissure, the wall of the aorta forms the uppermost part of the subaortic outflow. An incision through this area passes into the space between the facing surfaces of the aorta and pulmonary trunk. As the fac‐ ing left and right leaflets descend from this commissure, they are attached to the outlet muscular component of the left ventricle. Only a small part of this area in the normal heart is a true outlet septum, since both pulmonary and aortic valves are supported on their own sleeves of myocardium. Thus, although the outlet components of the right and left ventricle face each other, an incision below the aortic valve enters low into the infun‐ dibulum of the right ventricle. As the lateral part of the left coronary leaflet descends from the facing commissure to the base of the sinus, it becomes the only part of the aort‐ ic valve that is not intimately related to another cardiac chamber. [37]
