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Medina CK, Moya-Mendez ME, Aykut B, Jeffs S, Kang L, Evans A, Parker LE, Miller SG, Helke KL, Overbey DM, Turek JW, Rajab TK. Survival after partial heart transplantation in a piglet model. Sci Rep 2024; 14:12318. [PMID: 38811656 PMCID: PMC11136985 DOI: 10.1038/s41598-024-63072-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 05/24/2024] [Indexed: 05/31/2024] Open
Abstract
Partial heart transplantation (PHT) is a novel surgical approach that involves transplantation of only the part of the heart containing a valve. The rationale for this approach is to deliver growing heart valve implants that reduce the need for future re-operations in children. However, prior to clinical application of this approach, it was important to assess it in a preclinical model. To investigate PHT short-term outcomes and safety, we performed PHT in a piglet model. Yorkshire piglets (n = 14) were used for PHT of the pulmonary valve. Donor and recipient pairs were matched based on blood types. The piglets underwent PHT at an average age of 44 days (range 34-53). Post-operatively, the piglets were monitored for a period of two months. Of the 7 recipient piglets, one mortality occurred secondary to anesthesia complications while undergoing a routine echocardiogram on post-operative day 19. All piglets had appropriate weight gain and laboratory findings throughout the post-operative period indicating a general state of good health and rehabilitation after undergoing PHT. We conclude that PHT has good short-term survival in the swine model. PHT appears to be safe for clinical application.
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Affiliation(s)
- Cathlyn K Medina
- Department of Surgery, Duke University Medical Center, Durham, NC, USA
| | | | - Berk Aykut
- Department of Surgery, Duke University Medical Center, Durham, NC, USA
| | - Sydney Jeffs
- Department of Surgery, Duke University Medical Center, Durham, NC, USA
| | - Lillian Kang
- Department of Surgery, Duke University Medical Center, Durham, NC, USA
| | - Amy Evans
- Division of Cardiovascular Perfusion, Department of Clinical Sciences, Duke University, Durham, USA
| | - Lauren E Parker
- Department of Surgery, Duke University Medical Center, Durham, NC, USA
| | - Stephen G Miller
- Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | - Kristi L Helke
- Department of Comparative Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - Douglas M Overbey
- Department of Surgery, Duke University Medical Center, Durham, NC, USA
| | - Joseph W Turek
- Department of Surgery, Duke University Medical Center, Durham, NC, USA
| | - Taufiek Konrad Rajab
- Department of Surgery, Arkansas Children's Hospital, 1 Children's Way, Little Rock, AR, 72202, USA.
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Biomechanics of Pulmonary Autograft as Living Tissue: A Systematic Review. Bioengineering (Basel) 2022; 9:bioengineering9090456. [PMID: 36135002 PMCID: PMC9495771 DOI: 10.3390/bioengineering9090456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 09/01/2022] [Accepted: 09/04/2022] [Indexed: 11/17/2022] Open
Abstract
Introduction: The choice of valve substitute for aortic valve surgery is tailored to the patient with specific indications and contraindications to consider. The use of an autologous pulmonary artery (PA) with a simultaneous homograft in the pulmonary position is called a Ross procedure. It permits somatic growth and the avoidance of lifelong anticoagulation. Concerns remain on the functionality of a pulmonary autograft in the aortic position when exposed to systemic pressure. Methods: A literature review was performed incorporating the following databases: Pub Med (1996 to present), Ovid Medline (1958 to present), and Ovid Embase (1982 to present), which was run on 1 January 2022 with the following targeted words: biomechanics of pulmonary autograft, biomechanics of Ross operation, aortic valve replacement and pulmonary autograph, aortic valve replacement and Ross procedure. To address the issues with heterogeneity, studies involving the pediatric cohort were also analyzed separately. The outcomes measured were early- and late-graft failure alongside mortality. Results: a total of 8468 patients were included based on 40 studies (7796 in pediatric cohort and young adult series and 672 in pediatric series). There was considerable experience accumulated by various institutions around the world. Late rates of biomechanical failure and mortality were low and comparable to the general population. The biomechanical properties of the PA were superior to other valve substitutes. Mathematical and finite element analysis studies have shown the potential stress-shielding effects of the PA root. Conclusion: The Ross procedure has excellent durability and longevity in clinical and biomechanical studies. The use of external reinforcements such as semi-resorbable scaffolds may further extend their longevity.
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Cattapan C, Della Barbera M, Dedja A, Pavan P, Di Salvo G, Sabatino J, Avesani M, Padalino M, Guariento A, Basso C, Vida V. Mechanical and Structural Adaptation of the Pulmonary Root after Ross Operation in a Murine Model. J Clin Med 2022; 11:jcm11133742. [PMID: 35807025 PMCID: PMC9267924 DOI: 10.3390/jcm11133742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/18/2022] [Accepted: 06/20/2022] [Indexed: 01/25/2023] Open
Abstract
Background: The major limitation to the Ross operation is a progressive autograft dilation, possibly leading to reoperations. A murine model was created to evaluate pulmonary artery graft (PAG) adaptation to pressure overload. Methods: Lewis rats (n = 17) underwent heterotopic surgical implantation of a PAG, harvested from syngeneic animals (n = 17). A group of sham animals (n = 7) was used as a control. Seriated ultrasound studies of the PAG were performed. Animals were sacrificed at 1 week (n = 5) or 2 months (n = 15) and the PAG underwent mechanical and histopathological analyses. Results: Echography showed an initial increase in diameter (p < 0.001) and a decrease in peak systolic velocity (PSV). Subsequently, despite no change in diameter, an increase in PSV was observed (p < 0.01). After 1 week, the stiffness of the PAG and the aorta were similar, while at 2 months, the PAG appeared more rigid (p < 0.05). PAG’s histological analysis at 2 months revealed intimal hyperplasia development. The tunica media showed focal thinning of the elastic lamellae and normally distributed smooth muscle cells. Conclusions: We demonstrated a stiffening of the PAG wall after its implantation in systemic position; the development of intimal hyperplasia and the thinning of the elastic lamellae could be the possible underlying mechanism.
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Affiliation(s)
- Claudia Cattapan
- Pediatric and Congenital Cardiac Surgery Unit, Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, 35121 Padua, Italy; (C.C.); (A.D.); (M.P.); (A.G.)
| | - Mila Della Barbera
- Cardiovascular Pathology Unit, Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, 35121 Padua, Italy; (M.D.B.); (C.B.)
| | - Arben Dedja
- Pediatric and Congenital Cardiac Surgery Unit, Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, 35121 Padua, Italy; (C.C.); (A.D.); (M.P.); (A.G.)
| | - Piero Pavan
- Department of Industrial Engineering, University of Padua, 35131 Padua, Italy;
| | - Giovanni Di Salvo
- Pediatric Cardiology Unit, Department of Children and Woman’s Health, University of Padua, 35121 Padua, Italy; (G.D.S.); (J.S.); (M.A.)
| | - Jolanda Sabatino
- Pediatric Cardiology Unit, Department of Children and Woman’s Health, University of Padua, 35121 Padua, Italy; (G.D.S.); (J.S.); (M.A.)
| | - Martina Avesani
- Pediatric Cardiology Unit, Department of Children and Woman’s Health, University of Padua, 35121 Padua, Italy; (G.D.S.); (J.S.); (M.A.)
| | - Massimo Padalino
- Pediatric and Congenital Cardiac Surgery Unit, Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, 35121 Padua, Italy; (C.C.); (A.D.); (M.P.); (A.G.)
| | - Alvise Guariento
- Pediatric and Congenital Cardiac Surgery Unit, Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, 35121 Padua, Italy; (C.C.); (A.D.); (M.P.); (A.G.)
| | - Cristina Basso
- Cardiovascular Pathology Unit, Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, 35121 Padua, Italy; (M.D.B.); (C.B.)
| | - Vladimiro Vida
- Pediatric and Congenital Cardiac Surgery Unit, Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, 35121 Padua, Italy; (C.C.); (A.D.); (M.P.); (A.G.)
- Correspondence: ; Tel.: +39-049-821-2410
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Nappi F, Nenna A, Chello M. Structural Heart Valve Disease in the Era of Change and Innovation: The Crosstalk between Medical Sciences and Engineering. Bioengineering (Basel) 2022; 9:230. [PMID: 35735473 PMCID: PMC9220173 DOI: 10.3390/bioengineering9060230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 05/18/2022] [Indexed: 11/29/2022] Open
Abstract
In recent years, both cardiology and cardiovascular surgery have witnessed an era of consistently evolving changes which have dramatically transformed the course and management of cardiovascular disease [...].
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Affiliation(s)
- Francesco Nappi
- Cardiac Surgery, Centre Cardiologique du Nord de Saint-Denis, 93200 Paris, France
| | - Antonio Nenna
- Cardiovascular Surgery, Università Campus Bio-Medico di Roma, 00128 Rome, Italy; (A.N.); (M.C.)
| | - Massimo Chello
- Cardiovascular Surgery, Università Campus Bio-Medico di Roma, 00128 Rome, Italy; (A.N.); (M.C.)
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Nappi F. The role of the extracellular matrix in the development of heart valve disease: Underestimation or undercomprehension? J Card Surg 2022; 37:1623-1626. [PMID: 35352851 DOI: 10.1111/jocs.16445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 03/15/2022] [Indexed: 11/26/2022]
Abstract
The function of metalloproteinases of the extracellular matrix and their inhibitors has emerged with a crucial role in valve diseases. Both the expression of matrix metalloproteinases and their inhibitors are susceptible to modification in patients with severe mitral insufficiency. This process is due to substantial changes in the collagen structure during mechanical stress on the mitral valve leaflets. Several studies have measured the level of deformation of the mitral leaflets with the use of the finite element analysis method by establishing the stiffness of the cellular and extracellular elements of the mitral valve leaflets. Evidence suggested the possible underestimation of the stiffness of the leaflets. This implies greater stress on the components of the extracellular matrix in the circumferential and radial strains that involve the mitral leaflets during chronic regurgitation. The remodeling process during mechanical stress phenomena involves both the cellular compartment and the extracellular matrix and can be adaptive or maladaptive as showed in patients who receive a pulmonary autograft to replace the diseased aortic valve. However, adaptive remodeling can be driven using resorbable polymers that interfere with the extracellular matrix. Further investigation is required for the understanding of the mechanisms that determine the structural changes of the extracellular matrix and to prevent them.
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Affiliation(s)
- Francesco Nappi
- Department of Cardiac Surgery, Centre Cardiologique du Nord, Saint-Denis, France
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Tanaka D, Mazine A, Ouzounian M, El-Hamamsy I. Supporting the Ross procedure: preserving root physiology while mitigating autograft dilatation. Curr Opin Cardiol 2022; 37:180-190. [PMID: 35081548 DOI: 10.1097/hco.0000000000000949] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW The purpose of this article is to describe the optimized approach to nonrepairable aortic valve disease in young adults with a Ross procedure, while preserving the dynamic physiology of the aortic root. RECENT FINDINGS As the techniques for supporting pulmonary autografts continue to be refined, and the applicability of the Ross procedure continues to expand, an assessment of the various techniques based on aortic root physiology is warranted. Semi-resorbable scaffolds show promise in ovine models for improving the Ross procedure. Recent long-term outcomes for the Dacron inclusion technique in comparison to more physiologic methods of support emphasize the importance of balancing the prevention of early dilatation with the preservation of root haemodynamics. As this review will synthesize, the dynamic physiology of the root may be preserved even in patients at a higher risk of autograft dilatation. SUMMARY The favourable long-term outcomes of the Ross procedure can be partly attributed to the ability of the autograft to restore dynamism to the neoaortic root. Patient-specific modifications that respect root physiology can tailor the Ross procedure to address each patient's risk factors for early dilatation and late failure. As such, the Ross procedure should be recognized as an increasingly favourable solution for a wide spectrum of nonpreservable aortic valve disease in young adults.
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Affiliation(s)
| | | | - Maral Ouzounian
- Division of Cardiovascular Surgery, Peter Munk Cardiac Center, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Ismail El-Hamamsy
- Department of Cardiovascular Surgery, Mount Sinai Hospital, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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Van Hoof L, Verbrugghe P, Jones EAV, Humphrey JD, Janssens S, Famaey N, Rega F. Understanding Pulmonary Autograft Remodeling After the Ross Procedure: Stick to the Facts. Front Cardiovasc Med 2022; 9:829120. [PMID: 35224059 PMCID: PMC8865563 DOI: 10.3389/fcvm.2022.829120] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 01/17/2022] [Indexed: 12/12/2022] Open
Abstract
The Ross, or pulmonary autograft, procedure presents a fascinating mechanobiological scenario. Due to the common embryological origin of the aortic and pulmonary root, the conotruncus, several authors have hypothesized that a pulmonary autograft has the innate potential to remodel into an aortic phenotype once exposed to systemic conditions. Most of our understanding of pulmonary autograft mechanobiology stems from the remodeling observed in the arterial wall, rather than the valve, simply because there have been many opportunities to study the walls of dilated autografts explanted at reoperation. While previous histological studies provided important clues on autograft adaptation, a comprehensive understanding of its determinants and underlying mechanisms is needed so that the Ross procedure can become a widely accepted aortic valve substitute in select patients. It is clear that protecting the autograft during the early adaptation phase is crucial to avoid initiating a sequence of pathological remodeling. External support in the freestanding Ross procedure should aim to prevent dilatation while simultaneously promoting remodeling, rather than preventing dilatation at the cost of vascular atrophy. To define the optimal mechanical properties and geometry for external support, the ideal conditions for autograft remodeling and the timeline of mechanical adaptation must be determined. We aimed to rigorously review pulmonary autograft remodeling after the Ross procedure. Starting from the developmental, microstructural and biomechanical differences between the pulmonary artery and aorta, we review autograft mechanobiology in relation to distinct clinical failure mechanisms while aiming to identify unmet clinical needs, gaps in current knowledge and areas for further research. By correlating clinical and experimental observations of autograft remodeling with established principles in cardiovascular mechanobiology, we aim to present an up-to-date overview of all factors involved in extracellular matrix remodeling, their interactions and potential underlying molecular mechanisms.
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Affiliation(s)
- Lucas Van Hoof
- Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium
| | - Peter Verbrugghe
- Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium
| | | | - Jay D. Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States
| | - Stefan Janssens
- Department of Cardiology, University Hospitals Leuven, Leuven, Belgium
| | - Nele Famaey
- Biomechanics Section, KU Leuven, Leuven, Belgium
| | - Filip Rega
- Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium
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8
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Nappi F, Iervolino A, Avtaar Singh SS. The effectiveness and safety of pulmonary autograft as living tissue in Ross procedure: a systematic review. Transl Pediatr 2022; 11:280-297. [PMID: 35282027 PMCID: PMC8905099 DOI: 10.21037/tp-21-351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 01/14/2022] [Indexed: 11/06/2022] Open
Abstract
Background Reports on effectiveness and safety after the implant of pulmonary autograft (PA) living tissue in Ross procedure, to treat both congenital and acquired disease of the aortic valve and left ventricular outflow tract (LVOT), show variable durability results. We undertake a quantitative systematic review of evidence on outcome after the Ross procedure with the aim to improve insight into outcome and potential determinants. Methods A systematic search of reports published from October 1979 to January 2021 was conducted (PubMed, Ovid Medline, Ovid Embase and Cochrane library) reporting outcomes after the Ross procedure in patients with diseased aortic valve with or without LVOT. Inclusion criteria were observational studies reporting on mortality and/or morbidity after autograft aortic valve or root replacement, completeness of follow-up >90%, and study size n≥30. Forty articles meeting the inclusion criteria were allocated to two categories: pediatric patient series and young adult patient series. Results were tabulated for a clearer presentation. Results A total of 342 studies were evaluated of which forty studies were included in the final analysis as per the eligibility criteria. A total of 8,468 patients were included (7,796 in pediatric cohort and young adult series and 672 in pediatric series). Late mortality rates were remarkably low alongside similar age-matched mortality with the general population in young adults. There were differences in implantation techniques as regard the variability in stress and the somatic growth that recorded conflicting outcomes regarding the miniroot vs the subcoronary approach. Discussion The adaptability of lung autograft to allow for both stress variability and somatic growth make it an ideal conduit for Ross's operation. The use of the miniroot technique over subcoronary implantation for better adaptability to withstand varying degrees of stress is perhaps more applicable to different patient subgroups.
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Affiliation(s)
- Francesco Nappi
- Department of Cardiac Surgery, Centre Cardiologique du Nord, 93200 Saint-Denis, France
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9
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Van Hoof L, Claus P, Jones EAV, Meuris B, Famaey N, Verbrugghe P, Rega F. Back to the root: a large animal model of the Ross procedure. Ann Cardiothorac Surg 2021; 10:444-453. [PMID: 34422556 DOI: 10.21037/acs-2020-rp-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 03/29/2021] [Indexed: 12/16/2022]
Abstract
The excellent clinical outcomes of the Ross procedure and previous histological studies suggest that the pulmonary autograft has the potential to offer young patients a permanent solution to aortic valve disease. We aim to study the early mechanobiological adaptation of the autograft. To this end, we have reviewed relevant existing animal models, including the canine models which enabled Donald N Ross to perform the first Ross procedure in a patient in 1967. Two research groups recently evaluated the isolated effect of systemic pressures on pulmonary arterial tissue in an ovine model of a pulmonary artery interposition graft in the descending aorta. While this model is ideal to study the artery's biological response and the effect of external support, it does not recreate the complex environment of the aortic root. The freestanding Ross procedure has been performed in pigs and sheep before. These studies offered valuable insights into leaflet growth and histological remodeling, yet may be less relevant to adults undergoing the Ross procedure, as pronounced autograft dilatation was achieved by using small, rapidly growing animals. Therefore, a large animal model remains needed to determine the ideal conditions and surgical technique to ensure long-term autograft remodeling and valve function. We set out to develop an ovine model of the Ross procedure performed as a freestanding root replacement, acknowledging that the sheep's specific anatomy and the setting of an animal laboratory would mandate several modifications in surgical strategy. This article describes the development, surgical technique and early outcomes of our animal model while highlighting opportunities for further research.
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Affiliation(s)
- Lucas Van Hoof
- Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium.,Experimental Cardiac Surgery, KU Leuven, Leuven, Belgium
| | - Piet Claus
- Cardiovascular Imaging and Dynamics, KU Leuven, Leuven, Belgium
| | | | - Bart Meuris
- Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium.,Experimental Cardiac Surgery, KU Leuven, Leuven, Belgium
| | - Nele Famaey
- Biomechanics Section, KU Leuven, Leuven, Belgium
| | - Peter Verbrugghe
- Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium.,Experimental Cardiac Surgery, KU Leuven, Leuven, Belgium
| | - Filip Rega
- Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium.,Experimental Cardiac Surgery, KU Leuven, Leuven, Belgium
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10
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The Choice of Pulmonary Autograft in Aortic Valve Surgery: A State-of-the-Art Primer. BIOMED RESEARCH INTERNATIONAL 2021; 2021:5547342. [PMID: 33937396 PMCID: PMC8060091 DOI: 10.1155/2021/5547342] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/31/2021] [Accepted: 04/05/2021] [Indexed: 11/18/2022]
Abstract
The Ross procedure has long been seen as an optimal operation for a select few. The detractors of it highlight the issue of an additional harvesting of the pulmonary artery, subjecting the native PA to systemic pressures and the need for reintervention as reasons to avoid it. However, the PA is a living tissue and capable of adapting and remodeling to growth. We therefore review the current evidence available to discuss the indications, contraindications, harvesting techniques, and modifications in a state-of-the-art narrative review of the PA as an aortic conduit. Due to the lack of substantial well-designed randomized controlled trials (RCTs), we also highlight the areas of need to reiterate the importance of the Ross procedure as part of the surgical armamentarium.
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11
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The Use of Bioactive Polymers for Intervention and Tissue Engineering: The New Frontier for Cardiovascular Therapy. Polymers (Basel) 2021; 13:polym13030446. [PMID: 33573282 PMCID: PMC7866823 DOI: 10.3390/polym13030446] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/19/2021] [Accepted: 01/25/2021] [Indexed: 12/28/2022] Open
Abstract
Coronary heart disease remains one of the leading causes of death in most countries. Healthcare improvements have seen a shift in the presentation of disease with a reducing number of ST-segment elevation myocardial infarctions (STEMIs), largely due to earlier reperfusion strategies such as percutaneous coronary intervention (PCI). Stents have revolutionized the care of these patients, but the long-term effects of these devices have been brought to the fore. The conceptual and technologic evolution of these devices from bare-metal stents led to the creation and wide application of drug-eluting stents; further research introduced the idea of polymer-based resorbable stents. We look at the evolution of stents and the multiple advantages and disadvantages offered by each of the different polymers used to make stents in order to identify what the stent of the future may consist of whilst highlighting properties that are beneficial to the patient alongside the role of the surgeon, the cardiologist, engineers, chemists, and biophysicists in creating the ideal stent.
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12
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Ramachandra AB, Latorre M, Szafron JM, Marsden AL, Humphrey JD. Vascular adaptation in the presence of external support - A modeling study. J Mech Behav Biomed Mater 2020; 110:103943. [PMID: 32957235 DOI: 10.1016/j.jmbbm.2020.103943] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 04/24/2020] [Accepted: 06/17/2020] [Indexed: 10/24/2022]
Abstract
Vascular grafts have long been used to replace damaged or diseased vessels with considerable success, but a new approach is emerging where native vessels are merely supported, not replaced. Although external supports have been evaluated in diverse situations - ranging from aneurysmal disease to vein grafts or the Ross operation - optimal supports and procedures remain wanting. In this paper, we present a novel application of a growth and remodeling model well suited for parametrically exploring multiple designs of external supports while accounting for mechanobiological and immunobiological responses of the supported native vessel. These results suggest that a load bearing external support can reduce vessel thickening in response to pressure elevation. Results also suggest that the final adaptive state of the vessel depends on the structural stiffness of the support via a mechano-driven adaptation, although luminal encroachment may be a complication in the presence of chronic inflammation. Finally, the supported vessel can stiffen (structurally and materially) along circumferential and axial directions, which could have implications on overall hemodynamics and thus subsequent vascular remodeling. The proposed framework can provide valuable insights into vascular adaptation in the presence of external support, accelerate rational design, and aid translation of this emerging approach.
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Affiliation(s)
| | - Marcos Latorre
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Jason M Szafron
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Alison L Marsden
- Departments of Bioengineering and Pediatrics, Institute of Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA; Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, USA.
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13
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Nappi F, Nenna A, Lemmo F, Chello M, Chachques JC, Acar C, Larobina D. Finite Element Analysis Investigate Pulmonary Autograft Root and Leaflet Stresses to Understand Late Durability of Ross Operation. Biomimetics (Basel) 2020; 5:biomimetics5030037. [PMID: 32756408 PMCID: PMC7559879 DOI: 10.3390/biomimetics5030037] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 07/22/2020] [Accepted: 08/01/2020] [Indexed: 01/23/2023] Open
Abstract
Ross operation might be a valid option for congenital and acquired left ventricular outflow tract disease in selected cases. As the pulmonary autograft is a living substitute for the aortic root that bioinspired the Ross operation, we have created an experimental animal model in which the vital capacity of the pulmonary autograft (PA) has been studied during physiological growth. The present study aims to determine any increased stresses in PA root and leaflet compared to the similar components of the native aorta. An animal model and a mathematical analysis using finite element analysis have been used for the purpose of this manuscript. The results of this study advance our understanding of the relative benefits of pulmonary autograft for the management of severe aortic valve disease. However, it launches a warning about the importance of the choice of the length of the conduits as mechanical deformation, and, therefore, potential failure, increases with the length of the segment subjected to stress. Understanding PA root and leaflet stresses is the first step toward understanding PA durability and the regions prone to dilatation, ultimately to refine the best implant technique.
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Affiliation(s)
- Francesco Nappi
- Department of Cardiac Surgery, Centre Cardiologique du Nord de Saint-Denis, 93200 Paris, France
- Correspondence:
| | - Antonio Nenna
- Department of Cardiovascular Surgery, University Campus Bio-Medico of Rome, 00128 Rome, Italy; (A.N.); (M.C.)
| | - Francesca Lemmo
- Faculty of Engineering, University of Turin, 10124 Turin, Italy;
| | - Massimo Chello
- Department of Cardiovascular Surgery, University Campus Bio-Medico of Rome, 00128 Rome, Italy; (A.N.); (M.C.)
| | - Juan Carlos Chachques
- Department of Cardiovascular Surgery Carpentier Foundation, Pompidou Hospital, University Paris Descartes, 75015 Paris, France;
| | - Christophe Acar
- Department of Cardiovascular Surgery, Hopital de la Salpetriere, 75013 Paris, France;
| | - Domenico Larobina
- Institute for Polymers, Composites, and Biomaterials, National Research Council of Italy, 00185 Rome, Italy;
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14
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Burkhart HM, Mir A, Thompson JL. Commentary: The Ross Procedure: An Operation in Need of More Support. Semin Thorac Cardiovasc Surg 2020; 32:825-826. [PMID: 32610192 DOI: 10.1053/j.semtcvs.2020.06.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 06/13/2020] [Indexed: 11/11/2022]
Affiliation(s)
- Harold M Burkhart
- Division of Cardiovascular and Thoracic Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma.
| | - Arshid Mir
- Section of Pediatric Cardiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Jess L Thompson
- Division of Cardiovascular and Thoracic Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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15
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Nappi F, Spadaccio C, Acar C, El-Hamamsy I. Lights and Shadows on the Ross Procedure: Biological Solutions for Biological Problems. Semin Thorac Cardiovasc Surg 2020; 32:815-822. [PMID: 32439545 DOI: 10.1053/j.semtcvs.2020.04.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 04/20/2020] [Indexed: 11/11/2022]
Abstract
The Ross procedure represents a valid option for aortic valve replacement in young adults and was repeatedly shown to restore survival to that of the age- and sex-matched general population. However, its major drawback relies in the risk of pulmonary autograft (PA) dilation, negative histological remodeling and need for reoperation. Several techniques and materials to reinforce the PA have been proposed. They mainly include Dacron, personalized external aortic root support with a polyethylene terephthalate mesh system, autologous aortic tissue and bioresorbable materials. Synthetic materials, despite widely used in cardiac surgery, have significant biocompatibility issues with the PA and their interaction with this living structure translates into negative remodeling phenomena and disadvantageous biomechanical behaviors. Conversely, biomaterials with tailored degradable profiles might be able to reinforce while integrating with the PA and enhance its remodeling capabilities. The recent advancement in this field are here discussed.
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Affiliation(s)
- Francesco Nappi
- Department of Cardiac Surgery Center, Cardiologique du Nord de Saint-Denis, Paris, France.
| | - Cristiano Spadaccio
- Department of Cardiothoracic Surgery, Golden Jubilee National Hospital, Glasgow, United Kingdom; Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Christophe Acar
- Department of Cardiovascular Surgery, Hopital de la Salpetriere, Paris, France
| | - Ismail El-Hamamsy
- Department of Cardiac Surgery, Montreal Heart Institute, Montreal, Canada
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16
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Nappi F, Nenna A, Sing SSA, Timofeeva I, Mihos C, Gentile F, Chello M. Are the dynamic changes of the aortic root determinant for thrombosis or leaflet degeneration after transcatheter aortic valve replacement? J Thorac Dis 2020; 12:2919-2925. [PMID: 32642204 PMCID: PMC7330384 DOI: 10.21037/jtd.2020.02.01] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The role of the aortic root is to convert the accumulated elastic energy during systole into kinetic flow energy during diastole, in order to improve blood distribution in the coronary tree. Therefore, the sinuses of Valsalva of the aortic root are not predisposed to accept any bulky material, especially in case of uncrushed solid calcific agglomerates. This concept underlines the differences between surgical aortic valve replacement, in which decalcification is a main part of the procedure, and transcatheter aortic valve replacement (TAVR). Cyclic changes in shape and size of the aortic root influence blood flow in the Valsalva sinuses. Recent papers have been investigating the dynamic changes of the aortic root and whether those differences might be correlated with clinical effects, and this paper aims to summarize part of this flourishing literature. Post-TAVR aortic root remodeling, dynamic flow and TAVR complications might have a fluidodynamic background, and clinically observed side effects such as thrombosis or leaflet degeneration should be further investigated in basic researches. Also, aortic root changes could impact valve type and size selection, affecting the decision of over-sizing or under-sizing in order to prevent valve embolization or coronary ostia obstruction.
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Affiliation(s)
- Francesco Nappi
- Department of Cardiac Surgery, Centre Cardiologique du Nord de Saint-Denis, Paris, France
| | - Antonio Nenna
- Department of Cardiovascular Surgery, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Sanjeet Singh Avvtar Sing
- Department of Cardiac Surgery, Golden Jubilee National Hospital, Glasgow, UK.,Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
| | - Irina Timofeeva
- Department of Imaging, Centre Cardiologique du Nord de Saint-Denis, Paris, France
| | - Christos Mihos
- Echocardiography Lab, Columbia University Division of Cardiology, Mount Sinai Heart Institute, Miami, USA
| | | | - Massimo Chello
- Department of Cardiovascular Surgery, Università Campus Bio-Medico di Roma, Rome, Italy
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17
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Nappi F, Avtaar Singh SS, Acar C. Biomechanical future of the growing pulmonary autograft in Ross operation. Transl Pediatr 2020; 9:137-143. [PMID: 32477914 PMCID: PMC7237964 DOI: 10.21037/tp.2020.03.02] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 12/31/2019] [Indexed: 11/06/2022] Open
Abstract
It has been few years since the preliminary translational research study on mechanics performance of autologous pulmonary tissue were published to circumvent complication relies to SVD. Several studies reported the modification of pulmonary native autograft root subjected to dynamic stress strain in long-term outcomes of aortic valve replacement. Our multidisciplinary research team firstly describe the weave relationship between stress-strain, growth and remodelling in an experimental model of Ross Operation. From a biomechanical point of view, the rapid absorption of polydioxanone constituting the internal part of the device may limit the potential negative effect of excessive stretching and improvement of steeper curve in the circumferential response. Improvement of longitudinal stretching of pulmonary autograft by external component of device are indicative of auxetic effect of e-PTFE. Successful reinforcement with semiresorbable device can also be favourable to pulmonary autograft function in growing patients needing to match somatic growth. The attendant decrease in PA expansion and the preserved features of the valve leaflets enhances durability of Ross operation. Strengthening of the distal pulmonary root anastomosis using external reinforcement, modifying the ascending phase of the circumferential stress curve, might be advisable as previously described. PA is an ideal substitute for aortic valve replacement not only in Mr. Ross's dreams but also from the biomechanical point of view.
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Affiliation(s)
- Francesco Nappi
- Cardiac Surgery Centre Cardiologique du Nord de Saint-Denis, Paris, France
| | | | - Christophe Acar
- Department of Cardiovascular Surgery, Hospital de la Salpétrière, Paris, France
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18
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Nappi F, Mazzocchi L, Timofeva I, Macron L, Morganti S, Avtaar Singh SS, Attias D, Congedo A, Auricchio F. A Finite Element Analysis Study from 3D CT to Predict Transcatheter Heart Valve Thrombosis. Diagnostics (Basel) 2020; 10:diagnostics10040183. [PMID: 32225097 PMCID: PMC7235717 DOI: 10.3390/diagnostics10040183] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/21/2020] [Accepted: 03/23/2020] [Indexed: 11/29/2022] Open
Abstract
Background: Transcatheter aortic valve replacement has proved its safety and effectiveness in intermediate- to high-risk and inoperable patients with severe aortic stenosis. However, despite current guideline recommendations, the use of transcatheter aortic valve replacement (TAVR) to treat severe aortic valve stenosis caused by degenerative leaflet thickening and calcification has not been widely adopted in low-risk patients. This reluctance among both cardiac surgeons and cardiologists could be due to concerns regarding clinical and subclinical valve thrombosis. Stent performance alongside increased aortic root and leaflet stresses in surgical bioprostheses has been correlated with complications such as thrombosis, migration and structural valve degeneration. Materials and Methods: Self-expandable catheter-based aortic valve replacement (Medtronic, Minneapolis, MN, USA), which was received by patients who developed transcatheter heart valve thrombosis, was investigated using high-resolution biomodelling from computed tomography scanning. Calcific blocks were extracted from a 250 CT multi-slice image for precise three-dimensional geometry image reconstruction of the root and leaflets. Results: Distortion of the stent was observed with incomplete cranial and caudal expansion of the device. The incomplete deployment of the stent was evident in the presence of uncrushed refractory bulky calcifications. This resulted in incomplete alignment of the device within the aortic root and potential dislodgment. Conclusion: A Finite Element Analysis (FEA) investigation can anticipate the presence of calcified refractory blocks, the deformation of the prosthetic stent and the development of paravalvular orifice, and it may prevent subclinical and clinical TAVR thrombosis. Here we clearly demonstrate that using exact geometry from high-resolution CT scans in association with FEA allows detection of persistent bulky calcifications that may contribute to thrombus formation after TAVR procedure.
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Affiliation(s)
- Francesco Nappi
- Department of Cardiac Surgery, Centre Cardiologique du Nord de Saint-Denis, 93200 Paris, France
- Correspondence: ; Tel.: +331-4933-4104; Fax: +331-4933-4119
| | - Laura Mazzocchi
- Department of Civil Engineering and Architecture, University of Pavia, 27100 Pavia, Italy; (L.M.); (F.A.)
| | - Irina Timofeva
- Department of Imaging, Centre Cardiologique du Nord de Saint-Denis, 93200 Paris, France; (I.T.); (L.M.)
| | - Laurent Macron
- Department of Imaging, Centre Cardiologique du Nord de Saint-Denis, 93200 Paris, France; (I.T.); (L.M.)
| | - Simone Morganti
- Department of Electrical, Computer, and Biomedical Engineering University of Pavia, 27100 Pavia, Italy;
| | | | - David Attias
- Department of Cardiology, Centre Cardiologique du Nord de Saint-Denis, 93200 Paris, France;
| | - Antonio Congedo
- Department of Electronic Engineering, AKTIVE Reeds Manufacturing, Computer Science, 80123 Naples, Italy;
| | - Ferdinando Auricchio
- Department of Civil Engineering and Architecture, University of Pavia, 27100 Pavia, Italy; (L.M.); (F.A.)
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Nappi F, Avtaar Singh SS, Spadaccio C, Acar C. Ross operation 23 years after surgery: It should not be a "forgotten" option. J Card Surg 2020; 35:952-956. [PMID: 32115768 DOI: 10.1111/jocs.14489] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION The Ross procedure plays a pivotal part in both congenital and acquired diseases of the aortic valve, especially in young patients. The advantages of this procedure are widely known; however, long-term studies have shown dilation of the pulmonary autograft (PA) in up to 20% of patients in the second decade postoperatively. METHODS Three cases (ages 38, 51, and 53) who underwent the Ross procedure 23 years ago for bicuspid valves and endocarditis. Cases were followed-up with echocardiogram and computed tomography scan with three-dimensional reconstructions. RESULTS The PA showed normal function with favorable geometry alongside the thoracic aorta, while the pulmonary homograft preserved its function with a low degree of calcification. The mean annual expansion of the autograft was only 0.15, 0.30, and 0.40 mm with no pathological dilation after 20 years DISCUSSION: Ross operation provides excellent hemodynamic results while avoiding long-term anticoagulation and might constitute a valid adjunct in selected categories such as young or endocarditis patients.
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Affiliation(s)
- Francesco Nappi
- Department of Cardiac Surgery, Centre Cardiologique du Nord de Saint-Denis, Paris, France
| | | | - Cristiano Spadaccio
- Department of Cardiac Surgery, Golden Jubilee National Hospital, Glasgow, UK.,Department of Cardiac Surgery, Institute of Cardiovascular and Medical Science, University of Glasgow, Glasgow, UK
| | - Christophe Acar
- Department of Cardiac Surgery, La Pitié Salpetriere Hospital, Paris, France
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20
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Nappi F, Singh SSA. Gene therapy and regenerative tissue engineering in congenital heart disease. Transl Pediatr 2019; 8:356-359. [PMID: 31993346 PMCID: PMC6970115 DOI: 10.21037/tp.2019.04.10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Affiliation(s)
- Francesco Nappi
- Cardiac Surgery, Centre Cardiologique du Nord de Saint-Denis (CCN), Paris, France
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21
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Nappi F, Singh SSA, Lusini M, Nenna A, Gambardella I, Chello M. The use of allogenic and autologous tissue to treat aortic valve endocarditis. ANNALS OF TRANSLATIONAL MEDICINE 2019; 7:491. [PMID: 31700927 DOI: 10.21037/atm.2019.08.76] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The surgical treatment of aortic valve endocarditis (AVE) is generally performed using conventional mechanical or biological xenograft prosthesis, with limited use of aortic homograft (Ao-Homo) or pulmonary autograft (PA). Clinical evidence has demonstrated a clear contradiction between the proven benefits of Ao-Homo and PA in the context of infection and the very limited use of allogenic or autologous tissue in everyday clinical practice. This review aims to summarize the most recent and relevant literature in order to foster the scientific debate on the use of the use of allogenic and autologous tissue to treat AVE. The decisional process of the Heart Team should also include the preferences of the patient, his/her family, the general cardiologist or primary care physician. The use of allogenic or autologous valve substitute is beneficial if there is a high risk of recurrence of infection, avoiding extensive adhesiolysis and debridement of synthetic material. In any case, those procedures should be performed by highly trained centers to optimize outcomes.
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Affiliation(s)
- Francesco Nappi
- Department of Cardiac Surgery, Centre Cardiologique du Nord, Saint-Denis, Paris, France
| | | | - Mario Lusini
- Department of Cardiovascular Surgery, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Antonio Nenna
- Department of Cardiovascular Surgery, Università Campus Bio-Medico di Roma, Rome, Italy
| | | | - Massimo Chello
- Department of Cardiovascular Surgery, Università Campus Bio-Medico di Roma, Rome, Italy
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Vanderveken E, Vastmans J, Verbelen T, Verbrugghe P, Famaey N, Verbeken E, Treasure T, Rega F. Reinforcing the pulmonary artery autograft in the aortic position with a textile mesh: a histological evaluation. Interact Cardiovasc Thorac Surg 2019; 27:566-573. [PMID: 29912400 DOI: 10.1093/icvts/ivy134] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 03/25/2018] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES The Ross procedure involves replacing a patient's diseased aortic valve with their own pulmonary valve. The most common failure mode is dilatation of the autograft. Various strategies to reinforce the autograft have been proposed. Personalized external aortic root support has been shown to be effective in stabilizing the aortic root in Marfan patients. In this study, the use of a similar external mesh to support a pulmonary artery autograft was evaluated. METHODS The pulmonary artery was translocated as an interposition autograft in the descending thoracic aortas of 10 sheep. The autograft was reinforced with a polyethylene terephthalate mesh (n = 7) or left unreinforced (n = 3). After 6 months, a computed tomography scan was taken, and the descending aorta was excised and histologically examined using the haematoxylin-eosin and Elastica van Gieson stains. RESULTS The autograft/aortic diameter ratio was 1.59 in the unreinforced group but much less in the reinforced group (1.11) (P < 0.05). A fibrotic sheet, variable in thickness and containing fibroblasts, neovessels and foreign body giant cells, was incorporated in the mesh. Histological examination of the reinforced autograft and the adjacent aorta revealed thinning of the vessel wall due to atrophy of the smooth muscle cells. Potential spaces between the vessel wall and the mesh were filled with oedema. CONCLUSIONS Reinforcing an interposition pulmonary autograft in the descending aorta with a macroporous mesh showed promising results in limiting autograft dilatation in this sheep model. Histological evaluation revealed atrophy of the smooth muscle cell and consequently thinning of the vessel wall within the mesh support.
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Affiliation(s)
- Emma Vanderveken
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Julie Vastmans
- Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
| | - Tom Verbelen
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.,Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium
| | - Peter Verbrugghe
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.,Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium
| | - Nele Famaey
- Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
| | - Eric Verbeken
- Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
| | - Tom Treasure
- Clinical Operational Research Unit, UCL, London, UK
| | - Filip Rega
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.,Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium
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23
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Nappi F, Nenna A, Larobina D, Carotenuto AR, Jarraya M, Spadaccio C, Fraldi M, Chello M, Acar C, Carrel T. Simulating the ideal geometrical and biomechanical parameters of the pulmonary autograft to prevent failure in the Ross operation. Interact Cardiovasc Thorac Surg 2019. [PMID: 29538653 DOI: 10.1093/icvts/ivy070] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Reinforcements for the pulmonary autograft (PA) in the Ross operation have been introduced to avoid the drawback of conduit expansion and failure. With the aid of an in silico simulation, the biomechanical boundaries applied to a healthy PA during the operation were studied to tailor the best implant technique to prevent reoperation. METHODS Follow-up echocardiograms of 66 Ross procedures were reviewed. Changes in the dimensions and geometry of reinforced and non-reinforced PAs were evaluated. Miniroot and subcoronary implantation techniques were used in this series. Mechanical stress tests were performed on 36 human pulmonary and aortic roots explanted from donor hearts. Finite element analysis was applied to obtain high-fidelity simulation under static and dynamic conditions of the biomechanical properties and applied stresses on the PA root and leaflet and the similar components of the native aorta. RESULTS The non-reinforced group showed increases in the percentages of the mean diameter that were significantly higher than those in the reinforced group at the level of the Valsalva sinuses (3.9%) and the annulus (12.1%). The mechanical simulation confirmed geometrical and dimensional changes detected by clinical imaging and demonstrated the non-linear biomechanical behaviour of the PA anastomosed to the aorta, a stiffer behaviour of the aortic root in relation to the PA and similar qualitative and quantitative behaviours of leaflets of the 2 tissues. The annulus was the most significant constraint to dilation and affected the distribution of stress and strain within the entire complex, with particular strain on the sutured regions. The PA was able to evenly absorb mechanical stresses but was less adaptable to circumferential stresses, potentially explaining its known dilatation tendency over time. CONCLUSIONS The absence of reinforcement leads to a more marked increase in the diameter of the PA. Preservation of the native geometry of the PA root is crucial; the miniroot technique with external reinforcement is the most suitable strategy in this context.
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Affiliation(s)
- Francesco Nappi
- Department of Cardiac Surgery, Centre Cardiologique du Nord de Saint-Denis, Paris, France
| | - Antonio Nenna
- Department of Cardiovascular Surgery, University Campus Bio-Medico of Rome, Rome, Italy
| | - Domenico Larobina
- Institute for Polymers, Composites and Biomaterials, National Research Council of Italy, Rome, Italy
| | - Angelo Rosario Carotenuto
- Department of Structures for Engineering and Architecture and Interdisciplinary Research Center for Biomaterials, Università di Napoli 'Federico II', Naples, Italy
| | | | - Cristiano Spadaccio
- Department of Cardiothoracic Surgery, Golden Jubilee National Hospital, Glasgow, UK.,Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
| | - Massimiliano Fraldi
- Department of Structures for Engineering and Architecture and Interdisciplinary Research Center for Biomaterials, Università di Napoli 'Federico II', Naples, Italy
| | - Massimo Chello
- Department of Cardiovascular Surgery, University Campus Bio-Medico of Rome, Rome, Italy
| | - Christophe Acar
- Banc de Tissus Humains Hopital Saint Louis, Paris, France.,Department of Cardiac Surgery, Hopital La Pitie Salpetriere, Paris, France
| | - Thierry Carrel
- Deptartment of cardiovascular surgery, University Hospital of Bern, Bern, Switzerland
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Simulation and Deliberate Practice in a Porcine Model for Congenital Heart Surgery Training. Ann Thorac Surg 2017; 105:637-643. [PMID: 29275827 DOI: 10.1016/j.athoracsur.2017.10.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 09/12/2017] [Accepted: 10/02/2017] [Indexed: 12/30/2022]
Abstract
BACKGROUND Surgeons in training for congenital cardiac surgery face considerable challenges owing to procedure complexity, closely scrutinized outcomes, and a steep learning curve. Simulation methods have been initiated in other surgical specialties, but have yet to be established for congenital cardiac surgery trainees. The purpose of this study was to assess high-fidelity simulation as a method to train and improve skills of resident trainees learning critical components of index congenital cardiac surgical procedures. METHODS Using 5 neonatal piglets over a period of 2.5 days, the following procedures were simulated: Norwood procedure, arterial switch operation, neonatal Ross procedure, tetralogy of Fallot repair, systemic to pulmonary artery shunt procedures, transmediastinal coarctation repair, atrial septal defect repair, ventricular septal defect repair, and right ventricular to pulmonary artery conduit. Anastomoses were tested with saline, all procedures were timed and video recorded, and resident trainee techniques and skills were critiqued by the instructor. RESULTS All aspects of the procedures were simulated with minimal modifications. Anastomoses were tested, and the procedure successfully replicated without the pressures of operative time. Operative techniques involving suture placement in neonatal tissue, depth perception, and patch size estimation were corrected in real time, resulting in observed improvement of surgical skills. Video review allowed for further pedagogic value through examination and documentation of competency. CONCLUSIONS This neonatal porcine simulation model allows surgical trainees in congenital heart surgery to make and correct mistakes in a safe and controlled learning environment without compromising patient safety, thereby fostering surgeon competence and confidence.
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Biomechanical evaluation of a personalized external aortic root support applied in the Ross procedure. J Mech Behav Biomed Mater 2017; 78:164-174. [PMID: 29156355 DOI: 10.1016/j.jmbbm.2017.11.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 11/07/2017] [Accepted: 11/09/2017] [Indexed: 02/07/2023]
Abstract
A commonly heard concern in the Ross procedure, where a diseased aortic valve is replaced by the patient's own pulmonary valve, is the possibility of pulmonary autograft dilatation. We performed a biomechanical investigation of the use of a personalized external aortic root support or exostent as a possibility for supporting the autograft. In ten sheep a short length of pulmonary artery was interposed in the descending aorta, serving as a simplified version of the Ross procedure. In seven of these cases, the autograft was supported by an external mesh or so-called exostent. Three sheep served as control, of which one was excluded from the mechanical testing. The sheep were sacrificed six months after the procedure. Samples of the relevant tissues were obtained for subsequent mechanical testing: normal aorta, normal pulmonary artery, aorta with exostent, pulmonary artery with exostent, and pulmonary artery in aortic position for six months. After mechanical testing, the material parameters of the Gasser-Ogden-Holzapfel model were determined for the different tissue types. Stress-strain curves of the different tissue types show significantly different mechanical behavior. At baseline, stress-strain curves of the pulmonary artery are lower than aortic stress-strain curves, but at the strain levels at which the collagen fibers are recruited, the pulmonary artery behaves stiffer than the aorta. After being in aortic position for six months, the pulmonary artery tends towards aorta-like behavior, indicating that growth and remodeling processes have taken place. When adding an exostent around the pulmonary autograft, the mechanical behavior of the composite artery (exostent + artery) differs from the artery alone, the non-linearity being more evident in the former.
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26
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Burkhart HM, Thompson JL, Mir A. The Ross operation: Are we doing enough? J Thorac Cardiovasc Surg 2017; 154:783-784. [DOI: 10.1016/j.jtcvs.2017.05.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Accepted: 05/05/2017] [Indexed: 10/19/2022]
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Tran PK, Tsang VT, Cornejo PR, Torii R, Dominguez T, Tran-Lundmark K, Hsia TY, Hughes M, Muthialu N, Kostolny M. Midterm results of the Ross procedure in children: an appraisal of the subannular implantation with interrupted sutures technique†. Eur J Cardiothorac Surg 2017; 52:798-804. [DOI: 10.1093/ejcts/ezx113] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 02/26/2017] [Indexed: 12/30/2022] Open
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Abstract
The Ross operation provides several advantages compared to other valve substitutes to manage aortic valve disease, such as growth potential, excellent hemodynamics, freedom from oral anticoagulation and hemolysis, and better durability. However, progressive dilatation of the pulmonary autografts after Ross operation reflects the inadequate remodeling of the native pulmonary root in the systemic circulation, which results in impaired adaptability to systemic pressure and risk of reoperation after the first decade. A recently published article showed that remodeling increased wall thickness and decreased stiffness in the failed specimens after Ross operation, and the increased compliance might play a key role in determining the progressive long-term autograft root dilatation. Late dilatation can be counteracted by an external barrier which prevents failure. Therefore, an inclusion cylinder technique with a native aorta or a synthetic external support, such as Dacron, might stabilize the autograft root and improve long-term outcomes. In this article, we offer a prospective about the importance of biomechanical features in future developments of the Ross operation. Pre-clinical and clinical evaluations of the biomechanical properties of these reinforced pulmonary autografts might shed new light on the current debate about the long-term fate of the pulmonary autograft after Ross procedure.
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Affiliation(s)
- Francesco Nappi
- Department of Cardiac Surgery, Centre Cardiologique du Nord de Saint-Denis, Paris, France
| | - Antonio Nenna
- Department of Cardiovascular Surgery, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Cristiano Spadaccio
- Department of Cardiothoracic Surgery, Golden Jubilee National Hospital, Glasgow, UK
| | - Massimo Chello
- Department of Cardiovascular Surgery, Università Campus Bio-Medico di Roma, Rome, Italy
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Nappi F, Spadaccio C, Acar C. Use of allogeneic tissue to treat infective valvular disease: Has everything been said? J Thorac Cardiovasc Surg 2016; 153:824-828. [PMID: 27866779 DOI: 10.1016/j.jtcvs.2016.09.071] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 09/21/2016] [Accepted: 09/26/2016] [Indexed: 11/18/2022]
Affiliation(s)
- Francesco Nappi
- Cardiac Surgery Center, Cardiologique du Nord de Saint-Denis, Paris, France.
| | - Cristiano Spadaccio
- Department of Cardiothoracic Surgery, Golden Jubilee National Hospital, Glasgow, United Kingdom; Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Christophe Acar
- Department of Cardiovascular Surgery, Hôpital de la Salpétrière, Paris, France
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30
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Mookhoek A, Krishnan K, Chitsaz S, Kuang H, Ge L, Schoof PH, Bogers AJJC, Takkenberg JJM, Tseng EE. Biomechanics of Failed Pulmonary Autografts Compared With Normal Pulmonary Roots. Ann Thorac Surg 2016; 102:1996-2002. [PMID: 27457832 DOI: 10.1016/j.athoracsur.2016.05.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 04/27/2016] [Accepted: 05/02/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Progressive dilatation of pulmonary autografts after the Ross operation may reflect inadequate remodeling of the native pulmonary root to adapt to systemic circulation. Understanding the biomechanics of autograft root dilatation may aid designing strategies to prevent dilatation. We have previously characterized normal human pulmonary root material properties; however, the mechanical properties of failed autografts are unknown. In this study, failed autograft roots explanted during reoperation were acquired, and their material properties were determined. METHODS Failed pulmonary autograft specimens were obtained from patients undergoing reoperation after the Ross operation. Fresh human native pulmonary roots were obtained from the transplant donor network as controls. Biaxial stretch testing was performed to determine tissue mechanical properties. Tissue stiffness was determined at patient-specific physiologic stresses at pulmonary pressures. RESULTS Nonlinear stress-strain response was present in both failed autografts and normal pulmonary roots. Explanted pulmonary autografts were less stiff than were their native pulmonary root counterparts at 8 mm Hg (134 ± 42 vs 175 ± 49 kPa, respectively) (p = 0.086) and 25 mm Hg (369 ± 105 vs 919 ± 353 kPa, respectively) (p = 0.006). Autograft wall stiffness at both 8 and 25 mm Hg was not correlated with age at the Ross procedure (p = 0.898 and p = 0.813, respectively) or with time in the systemic circulation (p = 0.609 and p = 0.702, respectively). CONCLUSIONS Failed pulmonary autografts retained nonlinear response to mechanical loading typical of healthy human arterial tissue. Remodeling increased wall thickness but decreased wall stiffness in failed autografts. Increased compliance may explain progressive autograft root dilatation in autograft failures.
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Affiliation(s)
- Aart Mookhoek
- Department of Cardiothoracic Surgery, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Kapil Krishnan
- Department of Surgery, University of California San Francisco Medical Center and San Francisco Veterans Affairs Medical Center, San Francisco, California
| | - Sam Chitsaz
- Division of Cardiology, Department of Medicine, University of Texas at Houston, Houston, Texas
| | - Heide Kuang
- Department of Surgery, University of California San Francisco Medical Center and San Francisco Veterans Affairs Medical Center, San Francisco, California
| | - Liang Ge
- Department of Surgery, University of California San Francisco Medical Center and San Francisco Veterans Affairs Medical Center, San Francisco, California
| | - Paul H Schoof
- Department of Pediatric Cardiothoracic Surgery, Utrecht University Medical Center, Utrecht, The Netherlands
| | - Ad J J C Bogers
- Department of Cardiothoracic Surgery, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Johanna J M Takkenberg
- Department of Cardiothoracic Surgery, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Elaine E Tseng
- Department of Surgery, University of California San Francisco Medical Center and San Francisco Veterans Affairs Medical Center, San Francisco, California.
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Nappi F, Fraldi M, Spadaccio C, Carotenuto AR, Montagnani S, Castaldo C, Chachques JC, Acar C. Biomechanics drive histological wall remodeling of neoaortic root: A mathematical model to study the expression levels of ki 67, metalloprotease, and apoptosis transition. J Biomed Mater Res A 2016; 104:2785-93. [PMID: 27345614 DOI: 10.1002/jbm.a.35820] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 06/05/2016] [Accepted: 06/22/2016] [Indexed: 01/04/2023]
Abstract
The pulmonary artery autograft (PA) is the ideal substitute for aortic valve disease in children and young adult. However, it is harnessed by the issue of long-term dilation and regurgitation, often requiring surgery. PA implanted in aortic position during the growth phase in children undergoes a process of mechanical remodeling. We previously developed a semiresorbable armored prosthesis able to mechanically sustain the neoaorta preventing dilation and to gradually integrate with the PA wall inducing a progressive arterial-like tissue positive remodeling. We also described the mechanisms of growth, remodeling and stress shielding of the reinforced PA through a mathematical model. We sought to demonstrate the biological counterpart and the potential molecular mechanisms underlying this histological and mechanical remodeling. A specific mathematical model was developed to describe mechanical behavior of the PA. Mallory trichrome red staining and immunohistochemistry for MMP-9 were performed to elucidate extracellular matrix remodeling phenomena. Apoptosis and cell proliferation were determined by TUNEL assay and immunohistochemistry for Ki67, respectively. An histological remodeling phenomenon sustained by increased level of MMP-9, augmented cell proliferation and reduced apoptosis in the reinforced PA was demonstrated. The mathematical model predicted the biomechanical behavior subtended by the histological changes of the PA in these settings. Changes in metalloproteinases (MMP-9), cell proliferation and apoptosis are the main actors in the remodeling process occurring after transposition of the PA into systemic regimens. Use of semiresorbable reinforcements might induce a positive remodeling of the PA in the context of Ross operation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2785-2793, 2016.
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Affiliation(s)
- Francesco Nappi
- Department of Cardiac Surgery, Cardiac Surgery Centre, Cardiologique Du Nord De Saint-Denis, Paris, France.
| | - Massimiliano Fraldi
- Department of Structures for Engineering and Architecture and Interdisciplinary Research Center for Biomaterials, University of Napoli Federico II, Napoli, Italy
| | - Cristiano Spadaccio
- Department of Cardiothoracic Surgery, Golden Jubilee National Hospital, Clydebank, Glasgow, United Kingdom
| | - Angelo Rosario Carotenuto
- Department of Chemical, Materials and Production Engineering of the University of Naples Federico II, Naples, Italy
| | - Stefania Montagnani
- Department of Public Health, University of Naples Federico II, Naples, Italy
| | - Clotilde Castaldo
- Department of Public Health, University of Naples Federico II, Naples, Italy
| | - Juan Carlos Chachques
- Laboratory of Biosurgical Research, Carpentier Foundation, Pompidou Hospital, University Paris Descartes, Paris, France
| | - Christophe Acar
- Department of Cardiovascular Surgery, Hopital De La Salpétriere, Paris, France
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Nappi F, Carotenuto AR, Di Vito D, Spadaccio C, Acar C, Fraldi M. Stress-shielding, growth and remodeling of pulmonary artery reinforced with copolymer scaffold and transposed into aortic position. Biomech Model Mechanobiol 2015; 15:1141-57. [PMID: 26603438 DOI: 10.1007/s10237-015-0749-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 11/13/2015] [Indexed: 12/11/2022]
Abstract
Ross operation, i.e., the use of autologous pulmonary artery to replace diseased aortic valve, has been recently at the center of a vivid debate regarding its unjust underuse in the surgical practice. Keystone of the procedure regards the use of an autologous biologically available graft which would preserve the anticoagulative and tissue homeostatic functions normally exerted by the native leaflets and would harmoniously integrate in the vascular system, allowing for progressive somatic growth of aortic structures. With this respect, recently, some of the authors have successfully pioneered a large animal model of transposition of pulmonary artery in systemic pressure load in order to reproduce the clinical scenario in which this procedure might be applied and allow for the development and testing of different devices or techniques to improve the pulmonary autograft (PA) performance, by testing a bioresorbable mesh for PA reinforcement. In the present work, to support and supplement the in vivo animal experimentation, a mathematical model is developed in order to simulate the biomechanical changes in pulmonary artery subjected to systemic pressure load and reinforced with a combination of resorbable and auxetic synthetic materials. The positive biological effects on vessel wall remodeling, the regional somatic growth phenomena and prevention of dilatative degeneration have been analyzed. The theoretical outcomes show that a virtuous biomechanical cooperation between biological and synthetic materials takes place, stress-shielding guiding the physiological arterialization of vessel walls, consequently determining the overall success of the autograft system.
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Affiliation(s)
| | - Angelo Rosario Carotenuto
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Naples, Italy
| | - Donato Di Vito
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Naples, Italy.,Leibniz-Institut für Polymerforschung, Dresden, Germany
| | - Cristiano Spadaccio
- Department of Cardiothoracic Surgery, Golden Jubilee National Hospital, Clydebank, Glasgow, UK
| | - Cristophe Acar
- Department of Cardiovascular Surgery, Hopital de la Salpetriere, Paris, France
| | - Massimiliano Fraldi
- Department of Structures for Engineering and Architecture, University of Napoli Federico II, Naples, Italy. .,Interdisciplinary Research Center for Biomaterials, University of Napoli Federico II, Naples, Italy.
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Affiliation(s)
- Francesco Nappi
- Cardiac Surgery Center, Northern Cardiology Center Saint-Denis, Paris, France E-mail:
| | - Cristiano Spadaccio
- Department of Cardiothoracic Surgery, Golden Jubilee National Hospital, Clydebank, Glasgow, United Kingdom
| | - Christophe Acar
- Department of Cardiovascular Surgery, Hôpital de la Salpétrière, Paris, France
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A composite semiresorbable armoured scaffold stabilizes pulmonary autograft after the Ross operation: Mr Ross's dream fulfilled. J Thorac Cardiovasc Surg 2015; 151:155-64.e1. [PMID: 26602900 DOI: 10.1016/j.jtcvs.2015.09.084] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Revised: 08/10/2015] [Accepted: 09/12/2015] [Indexed: 01/04/2023]
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.
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Spadaccio C, Montagnani S, Acar C, Nappi F. Introducing bioresorbable scaffolds into the show. A potential adjunct to resuscitate Ross procedure. Int J Cardiol 2015; 190:50-2. [PMID: 25912121 DOI: 10.1016/j.ijcard.2015.04.098] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 04/14/2015] [Indexed: 10/23/2022]
Affiliation(s)
- Cristiano Spadaccio
- Department of Cardiothoracic Surgery, Golden Jubilee National Hospital, Clydebank, Glasgow, United Kingdom
| | - Stefania Montagnani
- Department of Public Health, University of Naples "Federico II", Naples, Italy
| | - Christophe Acar
- Department of Cardiovascular Surgery, Hôpital de la Salpétrière, Paris, France
| | - Francesco Nappi
- Cardiac Surgery Centre Cardiologique du Nord de Saint-Denis, Paris, France.
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Husain SA. The continued evolution of a transformational operation: New options for wrapping the Ross autograft? J Thorac Cardiovasc Surg 2015; 149:1142-3. [DOI: 10.1016/j.jtcvs.2015.01.076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 01/12/2015] [Indexed: 10/23/2022]
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