Commentary: Preventing pulmonary autograft dilatation: Many unanswered questions.

Central MessageInclusion of the pulmonary autograft inside a polyethylene terephthalate graft prevents late dilatation, but adversely changes biomechanical properties that may limit long-term durability.See Article page e103. Inclusion of the pulmonary autograft inside a polyethylene terephthalate graft prevents late dilatation, but adversely changes biomechanical properties that may limit long-term durability. See Article page e103. A normal aortic root has a complex anatomy, and its components move in a dynamic fashion with coordinated changes in shape and size during cardiac cycle that allows for normal hemodynamic parameters and optimal valve function during a lifetime.1Yacoub M.H. Kilner P.J. Birks E.J. Misfeld M. The aortic outflow and root: a tale of dynamism and crosstalk.Ann Thorac Surg. 1999; 68: S37-S43Abstract Full Text Full Text PDF PubMed Google Scholar None of the currently available aortic valve substitutes can entirely reproduce these sophisticated functions. Although a pulmonary autograft (PA) is a living structure capable of adaptative remodeling when transposed to the systemic circulation, it has specific morphometric features that may influence its long-term durability.2Azadani A.N. Chitsaz S. Matthews P.B. Jaussaud N. Leung J. Wisneski A. et al.Biomechanical comparison of human pulmonary and aortic roots.Eur J Cardiothorac Surg. 2012; 41: 1111-1116Crossref PubMed Scopus (45) Google Scholar The aortic and pulmonary valve leaflets have similar biomechanical properties, but the wall of the pulmonary artery is thinner with fewer elastic fibers, making it stiffer and less compliant when submitted to aortic pressures, predisposing it to progressive dilatation.2Azadani A.N. Chitsaz S. Matthews P.B. Jaussaud N. Leung J. Wisneski A. et al.Biomechanical comparison of human pulmonary and aortic roots.Eur J Cardiothorac Surg. 2012; 41: 1111-1116Crossref PubMed Scopus (45) Google Scholar,3Chauvette V. Chamberland M.E. El-Hamamsy I. A review of pulmonary autograft external support in the Ross procedure.Expert Rev Med Devices. 2019; 16: 981-988Crossref PubMed Scopus (12) Google Scholar Aortic valve replacement with the PA can be accomplished with different techniques, each with advantages and drawbacks.4Aboud A. Charitos E.I. Fujita B. Stierle U. Reil J.C. Voth V. et al.Long-term outcomes of patients undergoing the Ross procedure.J Am Coll Cardiol. 2021; 77: 1412-1422Crossref PubMed Scopus (45) Google Scholar Long-term follow-up data have demonstrated that, despite differences in modes of failure, freedom from PA dysfunction and/or the need for reoperations is relatively independent of the technique of implantation.4Aboud A. Charitos E.I. Fujita B. Stierle U. Reil J.C. Voth V. et al.Long-term outcomes of patients undergoing the Ross procedure.J Am Coll Cardiol. 2021; 77: 1412-1422Crossref PubMed Scopus (45) Google Scholar,5David T.E. Ouzounian M. David C.M. Lafreniere-Roula M. Manlhiot C. Late results of the Ross procedure.J Thorac Cardiovasc Surg. 2019; 157: 201-208Abstract Full Text Full Text PDF PubMed Scopus (72) Google Scholar The root replacement technique became the most frequently used possibly because transposing the PA as a single unit is the easiest and most reproducible way to obtain a competent valve with no or minimal geometrical distortion.5David T.E. Ouzounian M. David C.M. Lafreniere-Roula M. Manlhiot C. Late results of the Ross procedure.J Thorac Cardiovasc Surg. 2019; 157: 201-208Abstract Full Text Full Text PDF PubMed Scopus (72) Google Scholar The main concern with root replacement is the vulnerability to progressive dilatation of the PA with or without aortic valve incompetence, with reported incidence of freedom from reoperations varying from 69% to 93% at 15 years.5David T.E. Ouzounian M. David C.M. Lafreniere-Roula M. Manlhiot C. Late results of the Ross procedure.J Thorac Cardiovasc Surg. 2019; 157: 201-208Abstract Full Text Full Text PDF PubMed Scopus (72) Google Scholar,6Klieverik L.M. Takkenberg J.J. Bekkers J.A. Roos-Hesselink J.W. Witsenburg M. Bogers A.J. The Ross operation: a Trojan horse?.Eur Heart J. 2007; 28: 1993-2000Crossref PubMed Scopus (99) Google Scholar To avoid dilatation, some have advocated external reinforcement of the PA with polyethylene terephthalate grafts, polytetrafluoroethylene, or bovine pericardium.3Chauvette V. Chamberland M.E. El-Hamamsy I. A review of pulmonary autograft external support in the Ross procedure.Expert Rev Med Devices. 2019; 16: 981-988Crossref PubMed Scopus (12) Google Scholar The insertion of the PA inside a rigid synthetic graft may distort the normal geometry, restricting sinus expansion and autograft distensibility, which may influence the normal leaflet opening-and-closing mechanism, coronary flow reserve, and left ventricular impedance.3Chauvette V. Chamberland M.E. El-Hamamsy I. A review of pulmonary autograft external support in the Ross procedure.Expert Rev Med Devices. 2019; 16: 981-988Crossref PubMed Scopus (12) Google Scholar Zhu and colleagues7Zhu Y. Marin-Cuartas M. Park M.H. Imbrie-Moore A.M. Wilkerson R.J. Madira S. et al.Ex vivo biomechanical analysis of the Ross procedure using the modified inclusion technique in a 3D-printed left heart simulator.J Thorac Cardiovasc Surg. 2023; 165: e103-e116Abstract Full Text Full Text PDF Scopus (3) Google Scholar demonstrate, in an experimental model, that placing the PA inside a polyethylene terephthalate graft was associated with markedly increased velocities during opening and closing of the valve leaflets, a finding that has already been observed after aortic valve-sparing root replacement. The addition of anticommissural plication stitches was able to partially minimize these abnormalities, but still not similar to the unsupported root controls. Excessive cusp fluttering was clearly detected in both supported groups. In addition, the authors demonstrate an increased coaptation surface with some degree of cusp redundancy during diastole.7Zhu Y. Marin-Cuartas M. Park M.H. Imbrie-Moore A.M. Wilkerson R.J. Madira S. et al.Ex vivo biomechanical analysis of the Ross procedure using the modified inclusion technique in a 3D-printed left heart simulator.J Thorac Cardiovasc Surg. 2023; 165: e103-e116Abstract Full Text Full Text PDF Scopus (3) Google Scholar Although this may be helpful for achieving a competent valve, one might argue that this slight excess tissue may in fact be detrimental due to increased leaflet bending stresses during the cardiac cycle and may impair long-term durability. Until the long-term data are available for polyethylene-terephthalate–reinforced PA, I favor, in selected cases, the inclusion with autologous aorta, a technique that is effective in preventing PA dilatation with 96% freedom from reoperation after 18 years.8Skillington P.D. Mokhles M.M. Takkenberg J.J. Larobina M. O'Keefe M. Wynne R. et al.The Ross procedure using autologous support of the pulmonary autograft: techniques and late results.J Thorac Cardiovasc Surg. 2015; 149: S46-S52Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar Although Zhu and colleagues7Zhu Y. Marin-Cuartas M. Park M.H. Imbrie-Moore A.M. Wilkerson R.J. Madira S. et al.Ex vivo biomechanical analysis of the Ross procedure using the modified inclusion technique in a 3D-printed left heart simulator.J Thorac Cardiovasc Surg. 2023; 165: e103-e116Abstract Full Text Full Text PDF Scopus (3) Google Scholar have recognized that the experimental model has some limitations, they should be encouraged to further extend their investigations, including fatigue testing of the various versions of reinforced PA. Further laboratory studies coupled with animal investigations will eventually not only clarify the merits of the inclusion technique, but also help in refining different aspects of reinforced PA such as graft sizing and configurations and the use of alternative materials such as resorbable meshes.9Nappi F. Spadaccio C. Fraldi M. Montagnani S. Fouret P. Chachques J.C. et al.A composite semiresorbable armoured scaffold stabilizes pulmonary autograft after the Ross operation: Mr Ross's dream fulfilled.J Thorac Cardiovasc Surg. 2016; 151: 155-164.e1Abstract Full Text Full Text PDF PubMed Scopus (34) Google Scholar Ex vivo biomechanical analysis of the Ross procedure using the modified inclusion technique in a 3-dimensionally printed left heart simulatorThe Journal of Thoracic and Cardiovascular SurgeryVol. 165Issue 3PreviewThe inclusion technique was developed to reinforce the pulmonary autograft to prevent dilation after the Ross procedure. Anticommissural plication (ACP), a modification technique, can reduce graft size and create neosinuses. The objective was to evaluate pulmonary valve biomechanics using the inclusion technique in the Ross procedure with and without ACP. Full-Text PDF