oa Characterization of wall biomechanics of the pulmonary autograft after the Ross procedure

Background: There is continuing concern about the risk of long-term autograft dilatation and rupture following the Ross procedure. The aim of this study is to characterize the neo-aortic valve in terms of morphology and wall distensibility. Methods: Among 108 Ross patients undergoing yearly echocardiographic assessment in our unit, 17 (16%) had aortic root diameters of >45mm (DG) 14 ± 1 years after operation. In an attempt to characterize the autograft morphology and dynamics, 11 patients (age 47 ± 10) with dilated autografts underwent cardiac multi-slice computed tomography (CT). Dimensions and distensibility of the aortic root were derived from the cine-CT images. Morphological observation was also made with rapid prototyping models based on the multi-slice CT. The patients were compared with 11 age-matched normal controls (C, age 47 ± 9). Results: Sinus diameters (Ds) were increased in DG compared to C (50 ± 3 mm vs 31 ± 4 mm, p < 0.01). The non-coronary sinus of the autograft tended to enlarge to a greater extent than other two sinuses. Aortic diameters (Da) were also increased in DG (35 ± 6 mm vs 28 ± 3 mm, p < 0.01). DG patients had similar cyclic strain (7.2 ± 3.8% vs 8.3 ± 3.6%, p = 0.13) and distensibility (25 ± 14 vs 34 ± 14 MPa-1, p = 0.20). Conclusions: These data support the notion that the autograft root has similar physical properties to the normal aortic root despite significant dilation. This may have implications for both the selection of aortic root substitutes and the clinical management of Ross patients presenting with dilated roots.