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.

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.

The Use of Radial Artery for CABG: An Update.

We used the radial artery as a second target conduit for coronary artery bypass grafting since 1971. However, randomized clinical studies have demonstrated differences in clinical outcomes between the radial artery and other grafts because these trials are underpowered. As we proceed toward 50 years of experience with radial artery grafting, we examined the literature to define the best second-best target vessel for coronary artery bypass grafting. The literature was reviewed with emphasis, and a large number of randomized controlled trials, propensity-matched observational series, and meta-analyses were identified with a large patient population who received arterial conduit and saphenous vein grafts. The radial artery has been shown to be effective and safe when used as a second target conduit for coronary artery bypass grafting. Results and patency rates were superior to those for saphenous vein grafting. It has also been shown that the radial artery is a safe and effective graft as a third conduit into the territory of the artery right coronary artery. However, there is little evidence based on a few comparable series limiting the use of the gastroepiploic artery. In its fifth decade of use, we can finally deduced that the aorto-to-coronary radial bypass graft is the conduit of choice for coronary operations after the left internal thoracic artery to the left anterior descending artery.

Revisiting the guidelines and choice the ideal substitute for aortic valve endocarditis.

Aortic valve replacement is the most commonly performed cardiac surgical operation worldwide for infective endocarditis (IE). Long-term durability and avoidance of infection relapse are the treatment goals. However, no detailed guidelines on prosthesis selection and surgical strategy are available. Management should be guided by a comprehensive evaluation of infection extension and its microbiological characteristics, the clinical profile of the patient and the risk of infection recurrence. We conducted a literature search of the PubMed database, EMBASE and Cochrane Library (through November 2019) for studies reporting to the use of biological substitutes in aortic valve endocarditis (AVE). Studies comparing long-term outcomes in the use of allogenic and autologous with conventional prostheses were investigated. Conventional mechanical or stented xenografts are the preferred choice for localized aortic infection. In cases of complex IE with the involvement of the root or the aorto-mitral continuity, the use of homografts are recommended, according to surgeon's and center experience. Homograft use needs to be balanced against the risk of structural degeneration. Prosthetic bioroot or prosthetic valved conduit with a mechanical or bioprosthetic valve are acceptable alternatives. The choice of aortic valves substitute and surgical strategy in IE is multifaceted. Principles guiding the selection of prosthesis and surgical approach rely on the long-term durability and the avoidance of infection relapse. A decisional algorithm considering the extension of the infection and its microbiological characteristics, the clinical profile of the patient and the risk of infection recurrence is provided. A multidisciplinary effort is required to achieve consistent outcomes.

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.

Biomechanical future of the growing pulmonary autograft in Ross operation.

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.

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.

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

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.

The quest for the optimal surgical management of tricuspid valve endocarditis in the current era: a narrative review.

Tricuspid valve endocarditis (TVE) is a growing concern with increasing rates and mortality burden. The currently changing etiology, the antibiotic resistance and the raise in iatrogenic causes as with implantable cardiac devices [cardiac implantable electronic device (CIED)], represent a challenge for the management of these patients. The progressively widespread use of CIEDs is adding to the more commonly known intravenous (IV) drug abuse in the list of causes. Treatment strategies include medical therapy alone or surgery. From the surgical standpoint tricuspid valve repair, replacement or the staged procedure of valvectomy as bridge to replacement are available options. Treatment of endocarditis related to implantable device is another expanding field which requires a coordinated action with microbiologists in consideration of the microorganism antibiotic resistance. This review summarizes the currently available evidences on TVE including surgical indications, timing of interventions and technical considerations. The conflicting results of the available observational evidences and the non-unanimous consensus on many aspects of TVE impede to reach a definitive conclusion regarding the best management strategy and demands for randomized studies in this field.

Isolated aortic insufficiency valve repair with external ring annuloplasty: a standardized approach.

OBJECTIVES: Aortic valve (AV) insufficiency with normal root and ascending aorta is most frequently treated by valve replacement with significant prosthetic-related complications and reduced life expectancy. We compared the outcomes of a new standardized isolated AV repair approach using an external aortic annuloplasty ring at the subvalvular level (single ring annuloplasty) and the role of an additional supravalvular ring at the sinotubular junction (double ring annuloplasty). METHODS: Single centre data were collected from the Aortic Valve Insufficiency and ascending aorta Aneurysm InternATiOnal Registry (AVIATOR) between 2003 and 2017. A total of 93 patients (56 single ring and 37 double ring) underwent isolated AV repair. RESULTS: The overall 30-day mortality rate and the need for a permanent pacemaker were 1% and 2%, respectively. The overall survival rate at 6 years was similar for sex- and age-matched members of the general population (89% vs 95%; P = 0.1) and did not differ between the double and single ring groups (82% vs 93%; P = 0.4) at 6 years. There were no thromboembolic or bleeding events in the entire cohort. However, at 6 years, the cumulative incidence of valve-related reintervention was 26% in the single ring annuloplasty group compared to 3% in the double ring annuloplasty (P = 0.02) group. Similarly, at 6 years, the cumulative incidence of moderate-to-severe (>2) aortic insufficiency was 30% in the single ring annuloplasty group compared to 0% in the double ring annuloplasty group (P = 0.007). CONCLUSIONS: Standardized AV repair with external ring annuloplasty has a survival rate similar to that of the general population. The additional stabilization of the sinotubular junction with a second supravalvular ring (double ring annuloplasty) is associated with better outcomes compared to single subvalvular annuloplasty. It can be considered as a first line intervention for patients with isolated aortic insufficiency and pliable leaflets.

The Radial Artery for Coronary Bypass Grafting: The Fifth Decade.

BACKGROUND: In 1989, we reported the use of the radial artery as a second target conduit for coronary artery bypass grafting. However, underpowered randomized trials have reported differences in clinical outcomes between the radial artery and other grafts. As we approach 50 years of experience with radial artery grafting, we reviewed the literature to determine the second-best target vessel for coronary operations. METHODS: An electronic review of the literature with an emphasis on randomized controlled trials, propensity-matched observational series, and meta-analyses identified a large population of patients who received arterial conduit and saphenous vein grafts. RESULTS: The radial artery has been proven to be reliable as a second target conduit for coronary artery bypass grafting, with outcomes and patency rates superior to those for saphenous vein graft. It has also been proven to be both safe and effective as a third conduit in the territory of the right coronary artery. A paucity of evidence with few comparable series limits the use of the gastroepiploic artery. CONCLUSION: In its fifth decade of use, we can definitively conclude that the aorto-to-coronary radial bypass graft is the conduit of choice for coronary operations after the left internal thoracic artery to the left anterior descending artery.

Bicuspid aortic valve repair adapted to aortic phenotype.

The bicuspid aortic valve (BAV) is the most common congenital cardiovascular anomaly and may present with differing phenotypes including almost constant annular dilation. We have developed a standardized approach to BAV repair with a systematic adjunct of aortic annuloplasty according to the three phenotypes of the proximal aorta, which include a dilated aortic root, dilated ascending aorta and normal root and ascending aorta. In our cohort of 191 patients, freedom from AV-related re-intervention was 98% for remodeling with annuloplasty (n=100) and 100% for tubular aortic replacement with annuloplasty (n=31) at 8 years. In an isolated aortic insufficiency (AI) group, freedom from AV-related re-intervention varied from 72.4% with a single subvalvular annuloplasty ring (n=31) compared to 100% at 6 years when a double sub- and supra-valvular (STJ) annuloplasty ring was performed (n=29). Restoration of the annulus: sinotubular junction (STJ) ratio is a key factor to ensure longevity of the bicuspid valve repair and freedom from re-intervention.

Complementary Role of the Computed Biomodelling through Finite Element Analysis and Computed Tomography for Diagnosis of Transcatheter Heart Valve Thrombosis.

INTRODUCTION: The TAVR procedure is associated with a substantial risk of thrombosis. Current guidelines recommend catheter-based aortic valve implantation for prohibitive-high-risk patients with severe aortic valve stenosis but acknowledge that the aetiology and mechanism of thrombosis are unclear. METHODS: From 2015 to 2018, 607 patients with severe aortic valve stenosis underwent either self-expandable or balloon-expandable catheter-based aortic valve implantation at our institute. A complementary study was designed to support computed tomography as a predictor of complications using an advanced biomodelling process through finite element analysis (FEA). The primary evaluation of study was the thrombosis of the valve at 12 months. RESULTS: At 12 months, 546 patients had normal valvular function. 61 patients had THVT while 6 showed thrombosis and dislodgement with deterioration to NYHA Class IV requiring rehospitalization. The FEA biomodelling revealed a strong link between solid uncrushed calcifications, delayed dislodgement of TAVR and late thrombosis. We observed an interesting phenomenon of fibrosis/calcification originating at the level of the misplaced valve, which was the primary cause of coronary obstruction. CONCLUSION: The use of cardiac CT and predictive biomodelling should be integrated into routine practice for the selection of TAVR candidates and as a predictor of negative outcomes given the lack of accurate investigations available. This would assist in effective decision-making and diagnosis especially in a high-risk cohort of patients.