A composite semiresorbable armoured scaffold stabilizes pulmonary autograft after the Ross operation: Mr Ross's dream fulfilled

• Published in: The Journal of thoracic and cardiovascular surgery Vol. 151; no. 1; pp. 155 - 164.e1
• Main Authors: Nappi, Francesco, MD, Spadaccio, Cristiano, MD, PhD, Fraldi, Massimiliano, PhD, Montagnani, Stefania, MD, Fouret, Pierre, MD, Chachques, Juan Carlos, MD, PhD, Acar, Christophe, MD, PhD
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2016
• Subjects: Absorbable Implants; Age Factors; Animals; Aorta, Thoracic - diagnostic imaging; Aorta, Thoracic - growth & development; Aorta, Thoracic - metabolism; Aorta, Thoracic - surgery; Aortic Aneurysm - diagnosis; Aortic Aneurysm - etiology; aortic remodeling; Aortography; Autografts; Bioprosthesis; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation - adverse effects; Blood Vessel Prosthesis Implantation - instrumentation; Cardiothoracic Surgery; Dilatation, Pathologic; Extracellular Matrix - metabolism; Graft Survival; Matrix Metalloproteinase 9 - metabolism; Models, Animal; Polydioxanone - chemistry; Polytetrafluoroethylene - chemistry; Prosthesis Design; Pulmonary Artery - transplantation; pulmonary autograft; Ross operation; Sheep; stress shielding; Time Factors; tissue engineering; Tissue Scaffolds; Ultrasonography; Vascular Remodeling; tissue engineering; aortic remodeling; Ross operation; expanded polytetrafluoroethylene; stress shielding; pulmonary autograft; 26.1; PA; 39.4; 20.2; polydioxanone; 26.6; ePTFE; PDS
• ISSN: 0022-5223; 1097-685X
• DOI: 10.1016/j.jtcvs.2015.09.084

Abstract Objectives Use of resorbable external reinforcement of the pulmonary autograft during the Ross operation has been suggested, but the differential regional potential for dilation of the aorta, mainly regarding the neo-root and the neo-Valsalva sinuses, represents an unresolved issue. Auxetic materials could be useful in preventing dilation given their favorable mechanical properties. We designed a composite semiresorbable armoured bioprosthesis constituted by polydioxanone and expanded polytetrafluoroethylene and evaluated its effectiveness as a pulmonary autograft reinforcement device in an animal model of the Ross procedure. Methods An experimental model of the Ross procedure was performed in 20 three-month-old growing lambs. The pulmonary autograft was alternatively nonreinforced (control group n = 10) or reinforced with composite bioprosthesis (reinforced group n = 10). Animals were followed up during growth for 6 months by angiography and echocardiography. Specific stainings for extracellular matrix and immunohistochemistry for metalloproteinase-9 were performed. Results Reference aortic diameter increased from 14 ± 1 mm to 19 ± 2 mm over 6 months of growth. In the control group, pulmonary autograft distension (28 ± 2 mm) was immediately noted, followed by aneurysm development at 6 months (40 ± 2 mm, P  < .001 vs reference). In the reinforced group, an initial dilation to 18 ± 1 mm was detected and the final diameter was 27 ± 2 mm (42% increase). Two deaths due to pulmonary autograft rupture occurred in the control group. On histology, the control group showed medial disruption with connective fibrous replacement, whereas in the reinforced group compensatory intimal hyperplasia was present in the absence of intimal tears. The bioprosthesis promoted a positive matrix rearrangement process favoring neoarterialization and elastic remodeling as demonstrated on specific staining for elastin collagen and metalloproteinase-9. Conclusions The device adapted and functionally compensated for the characteristics of autograft growth, guaranteeing a reasonable size of the autograft at 6 months, but more important, because the device is biocompatible, it did not disrupt the biological process of growth or cause inflammatory damage to the wall.