MORPHOLOGY OF THE PULMONARY AND AORTIC ROOTS WITH REGARD TO THE PULMONARY AUTOGRAFT PROCEDURE

Aortic root replacement with the pulmonary autograft warrants a thorou gh histologic comparison of the morphologic characteristics of the pul monary and aortic roots, For this purpose nine normal heart specimens (7 neonatal and 2 adult hearts) were studied, Histologic study confirm ed the collagenous anulus in both roots to be a complex circular-shape d structure, intricately interposed between the elastic lamellae of th e arterial wall and the ventricular structures of the heart, In the si nus the elastic lamellae of the arterial wall continue along the lumin al side with collagen being situated at the outside, At the interleafl et triangle this relation is reversed, Surprisingly, islets of elastic fibers were found in the otherwise completely collagenous interleafle t triangles, The amount of elastic lamella distal to the commissures w as in both arteries higher than that in the middle of the sinuses, wit h a preponderance in the aorta as compared with the pulmonary trunk. T he pulmonary root anulus proximally inserts into the relatively thin r ight ventricular myocardium, whereas the aortic root anulus inserts in to the thick left ventricular myocardium and several fibrous structure s, The pulmonary root is hardly supported hy the right ventricular myo cardium, whereas the aortic root is supported by its wedged position b etween the left and right atrioventricular anuli and the bulging thick left ventricular myocardium. When the pulmonary autograft is used for aortic root replacement it should be inserted as proximally as possib le to get the support of the fibrous structures of the left ventricula r outflow tract and the surrounding ventricular and atrial myocardium.