Ross operation 23 years after surgery: It should not be a "forgotten" option

A Literature Review on the Use of Aortic Allografts in Modern Cardiac Surgery for the Treatment of Infective Endocarditis: Is There Clear Evidence or Is It Merely a Perception?

Infective valve endocarditis is caused by different pathogens and 60% of those involve the aortic valve with valve failure. Although S. aureus is recognized as the most frequently isolated causative bacterium associated with IE in high-income countries, Gram-positive cocci nevertheless play a crucial role in promoting infection in relation to their adhesive matrix molecules. The presence of pili on the surface of Gram-positive bacteria such as in different strains of Enterococcus faecalis and Streptococcus spp., grants these causative pathogens a great offensive capacity due to the formation of biofilms and resistance to antibiotics. The indications and timing of surgery in endocarditis are debated as well as the choice of the ideal valve substitute to replace the diseased valve(s) when repair is not possible. We reviewed the literature and elaborated a systematic approach to endocarditis management based on clinical, microbiological, and anatomopathological variables known to affect postoperative outcomes with the aim to stratify the patients and orient decision making. From this review emerges significant findings on the risk of infection in the allograft used in patients with endocarditis and no endocarditis etiology suggesting that the use of allografts has proved safety and effectiveness in patients with both pathologies.

The Use of the Cryopreserved Aortic Homograft for Aortic Valve Replacement: Is It Still an Option?

The indications for cryopreserved allografts in aortic valve replacement are still debatable. We aim to identify factors influencing early and long-term durability of the aortic homograft and to define subgroups of patients with an improved long-term quality of life, survival, and freedom from structural valve degeneration (SVD). We evaluated our series of 210 patients who underwent allograft implantation with a retrospective cohort study design over a period of 20 years. Endpoints were overall mortality, cardiac mortality related to SVD, the incidence of SVD, reoperation, and a composite endpoint comprising major adverse cardiac and cerebrovascular events (MACCEs), which includes cardiac death both related and not related to SVD, subsequent aortic valve surgery, new or recurrent infection of implanted allograft, recurrent aortic regurgitation, rehospitalization for heart failure, an increase in New York Heart Association (NYHA) class of ≥1, or cerebrovascular events. The primary indication for surgery was endocarditis (48%), which was also a predisposing factor for increased cardiac mortality. Overall mortality was 32.4% with a 27% incidence of SVD and mortality associated with SVD of 13.8%. Reoperation occurred in 33.8% and MACCEs in 54.8%. Long-term NYHA functional class and echocardiographic parameters improved over time. Statistical analysis demonstrated that root replacement technique and adult age were protective factors for SVD. We found no statistically significant difference in the clinical outcomes analyzed between women of childbearing age who had children after surgery and the rest of the women. The cryopreserved allograft is still a valid option in aortic valve replacement, providing acceptable durability and clinical outcomes with optimal hemodynamic performance. SVD is influenced by the implantation technique. Women of childbearing age might have additional benefits from this procedure.

Biomechanics of Pulmonary Autograft as Living Tissue: A Systematic Review

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.

The effectiveness and safety of pulmonary autograft as living tissue in Ross procedure: a systematic review

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.

The Choice of Pulmonary Autograft in Aortic Valve Surgery: A State-of-the-Art Primer

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.

A narrative review of early surgery versus conventional treatment for infective endocarditis: do we have an answer?

The most appropriate strategy and timing for surgery in infective endocarditis (IE) remains an argument of debate. Despite some authors promote the adoption of an early surgical approach (within 48 hours) to limit mortality and complications, no robust randomized trials are available on this argument and the evidence on this subject remain at the "expert opinion" level. Additionally, the different messages promulgated by the American and European guidelines contributed to fuel confusion regarding the relative priority of the surgical over medical therapy in IE. The European Society of Cardiology (ESC) guidelines individuates three level of urgency: emergency surgery, to be performed within 24 hours; urgent surgery, recommended within a few days; elective surgery to be performed after 1-2 weeks of antibiotic therapy. Urgent surgery is recommended for most cases of IE. In the American Heart Association (AHA)'s guidelines define early surgery as "during the initial hospitalization and before completion of a full course of antibiotics." Some of the available evidences showed that are no proven benefits in delaying surgery if a definite diagnosis of IE has been established. However, this argument is controversial across the literature and several factors including the center specific experience can play a role in decision-making. In this review the latest evidences on IE clinical and surgical characteristics along with the current studies on the adoption of an early surgical approach are analyzed to clarify whether enough evidence is available to inform an update of the guidelines.

Sharing of decision-making for infective endocarditis surgery: a narrative review of clinical and ethical implications

Infective endocarditis (IE) is nowadays one of the most challenging disease in cardiac surgery because of its multifaceted clinical and anatomical presentation. Despite the many clinical and surgical advances achieved in the past 60 years, there is a lack of evidence regarding the ideal strategy. The present review aims to investigate and highlight two main novel concepts for the decision-making of the best substitute. Firstly, the concept of an "endocarditis team": a coordinated multidisciplinary effort in the diagnostic work-up, especially in conditions of high risk of embolization or clinical deterioration. A good "endocarditis team" has the role to overcome such problem, in order to ensure a prompt and balanced strategy. Secondly, which ethical considerations are required to drive the choice of valvular substitute. The choice of best valve substitute is a relevant issue of debate, not only with operative but also prognostic and accordingly ethical aftermaths. Many different solutions have been developed to substitute the infected valve. Among these: mechanical prosthesis (MP), biological stented prosthesis (BP), sutureless bioprosthesis and cryopreserved homografts (CHs). Patients need to be informed in detail about the technical issues pertaining the use of these valve substitute. We will discuss the evidences regarding the risk of recurrent infections or future potentially severe calcification of aortic homograft valve and wall (in other words, the failure of the homograft) and the difficulties in managing the reoperation.

A management framework for left sided endocarditis: a narrative review

Left sided endocarditis (LSE) can include the entirety or portion of mitral and/or aortic valve and the structures in their anatomical contiguity and represent a significant portion of emergency surgical activity. Literature and guidelines on the management of LSE relies mainly on observational studies given the difficulty in designing randomized trials in emergency settings. Heart teams (HT) are often called in to difficult decisions on the most appropriate strategy to adopted in case of LSE. Decision-making should take into account the localization and the extension of the infection, patient preoperative status and comorbidities, presence of a previous valve prosthesis and best timing for surgery. Despite evidence suggests that early surgery may improve survival in patients with complicated infective endocarditis (IE), an increased risk of recurrence and postoperative valvular dysfunctions has been reported. The most important factors associated with long-term outcomes are preoperative multiorgan failure, prosthetic mechanical valve IE, vegetation size ≥15 mm, and timing of surgical treatment. Importantly, up to one third of potential candidates do not undergo surgery and these patients experience extremely high mortality rates. Another important point regards the choice of the optimal valve substitute to be used according to the different clinical situation. The lack of RCT in this field and the difficulty to design this type of studies in the case of non-elective conditions further complicates the possibility to achieve a univocal consensus on the best strategy to be adopted in each form of LSE and further validation studies are needed. On the basis of the current evidences a decisional algorithm is proposed summarizing all the crucial aspects in the management of LSE.

Learning From Controversy: Contemporary Surgical Management of Aortic Valve Endocarditis

Aortic valve replacement is the commonest cardiac surgical operation performed worldwide for infective endocarditis (IE). Long-term durability and avoidance of infection relapse are goals of the procedure. However, no detailed guidelines on prosthesis selection and surgical strategies guided by the comprehensive evaluation of the extension of the infection and its microbiological characteristics, clinical profile of the patient, and risk of infection recurrence are currently available. Conventional mechanical or stented xenografts are the preferred choice for localized aortic infection. However, in cases of complex IE with the involvement of the root or the aortomitral continuity, the use of homograft is suggested according to the surgeon and center experience. Homograft use should be counterbalanced against the risk of structural degeneration. Prosthetic bioroot or prosthetic valved conduit (mechanical and bioprosthetic) are also potentially suitable alternatives. Further development of preservation techniques enabling longer durability of allogenic substitutes is required. We evaluate the current evidence for the use of valve substitutes in aortic valve endocarditis and propose an evidence-based algorithm to guide the choice of therapy. We performed a systemic review to clarify the contemporary surgical management of aortic valve endocarditis.

Finite Element Analysis Investigate Pulmonary Autograft Root and Leaflet Stresses to Understand Late Durability of Ross Operation

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.

Lights and Shadows on the Ross Procedure: Biological Solutions for Biological Problems

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.