Stented cryopreserved aortic allograft for reconstruction of long-segment post-tuberculosis tracheal stenosis.

Tracheobronchial tuberculosis is one of the conditions causing long segment tracheal stenosis and is a clinically challenging scenario. This report describes a successful tracheal reconstruction in a 44-year-old man with long-segment post-tuberculosis tracheobronchial stenosis, utilizing a stented cryopreserved aortic allograft. The procedure was necessitated by the failure of conventional treatments. The stenotic segment was resected and replaced with a cryopreserved aortic allograft, supported by a metallic stent to maintain airway patency. Post-surgery, the patient experienced resolution of dyspnea without major complications. Currently, at 33 months post-operation, the patient enjoys an enhanced quality of life with effective breathing, speaking, swallowing abilities, and has resumed normal daily activities, with regular bronchoscopic follow-ups. This report demonstrates a novel approach for managing challenging tuberculosis-induced long segment airway stenosis.

Feasibility of tracheal reconstruction using silicone-stented aortic allografts.

OBJECTIVES: Tracheal reconstruction post-extensive resection remains an unresolved challenge in thoracic surgery. This study evaluates the use of aortic allografts (AAs) for tracheal replacement and reconstruction in a rat model, aiming to elucidate the underlying mechanisms of tracheal regeneration. METHODS: AAs from female rats were employed for tracheal reconstruction in 36 male rats, with the replacement exceeding half of the tracheal length. To avert collapse, silicone stents were inserted into the AA lumens. No immunosuppressive therapy was administered. The rats were euthanized biweekly, and the AAs were examined for neovascularization, cartilage formation, respiratory epithelial ingrowth, submucosal gland regeneration and the presence of the Sex-determining region of Y-chromosome (SRY) gene. RESULTS: All procedures were successfully completed without severe complications. The AA segments were effectively integrated into the tracheal framework, with seamless distinction at suture lines. Histological analysis indicated an initial inflammatory response, followed by the development of squamous and mucociliary epithelia, new cartilage ring formation and gland regeneration. In situ hybridization identified the presence of the SRY gene in newly formed cartilage rings, confirming that regeneration was driven by recipient cells. CONCLUSIONS: This study demonstrates the feasibility of AAs transforming into functional tracheal conduits, replicating the main structural and functional characteristics of the native trachea. The findings indicate that this approach offers a novel pathway for tissue regeneration and holds potential for treating extensive tracheal injuries.

Circumferential tracheal replacement with silicone stent supported, cryopreserved aortic homograft.

Treatment of long-segment tracheal defects remains a challenge in thoracic surgery with no standard surgical option. Aortic allografts have been used for this purpose with varying degrees of success. In a patient that suffered anastomotic dehiscence after tracheal resection with primary anastomosis, we performed complete tracheal resection and replacement using a stented circumferential aortic allograft. Currently, this patient is able to breathe normally without tracheostomy assistance 22 months postoperatively. Our report is the first in the English literature of long-term survival without tracheostomy dependence and close interval follow-up after circumferential tracheal resection and replacement with a cryopreserved aortic allograft.

Tracheal Replacement Techniques and Associated Mortality: A Systematic Review.

OBJECTIVE: Tracheal replacement is a crucial operation to enhance the quality of life for patients with extensive tracheal lesions. The most suitable surgical techniques for different clinical conditions remain a topic of debate. Through a reviewing of the relevant literature, this study investigated the association between surgical techniques and mortality rate. DATA SOURCES: Studies were collected from PubMed, Embase, the Web of Science, the Cochrane Center Register of Controlled Trials, and ClinicalTrials.gov. METHODS: This systematic review encompassed literature from the inception of each database to May 10, 2023, focusing on tracheal replacement for patients who underwent circumferential resection of the trachea or partial resection with preservation of the posterior membranous wall. Non-human and non-clinical studies were excluded. RESULTS: About 31 studies were included in the assessment comprising a combination of case reports and case series, and 118 patients underwent tracheal replacement through four underlying methodologies, including tracheal allotransplantation, autologous tissue reconstruction, bioprosthetic reconstruction, or tissue engineering surgery. Each modality exhibits unique advantages and disadvantages, leading to variable outcomes in clinical application. CONCLUSION: Tracheal replacement is challenging due to the absence of an ideal substitution or graft material. Despite limited clinical successes observed across various modalities, we believe autologous tissue reconstruction for tracheal replacement has the advantage of broadest indications, low rejection rate, and avoidance of immunosuppressive agents. Future research should focus on achieving tracheal replacement that preserves mucociliary clearance, lateral rigidity, and longitudinal flexibility. LEVEL OF EVIDENCE: NA Laryngoscope, 134:1517-1522, 2024.

Preliminary results in tracheal replacement using stented aortic matrices for primary extensive tracheal cancer.

Objective: Recent studies have demonstrated the feasibility and favorable long-term results of tracheobronchial replacement using stented cryopreserved aortic allografts. We propose to investigate the outcomes of this emerging technique in the subgroup of patients with extensive tracheal cancer. Methods: This study was based on 13 patients with primary extensive tracheal cancer extracted from the prospective registry TRITON-01 (ClinicalTrials.gov Identifier: NCT04263129), which included 40 patients in total. We analyzed early and late outcomes in this subset of patients. Results: From March 2019 to September 2022, 13 patients were included in the study. There were 9 female and 4 male patients, with a mean age of 53.9 years [36-71 years]. They had tracheal replacement for extended adenoid cystic carcinoma (n = 11), squamous cell carcinoma (n = 1), and mucoepidermoid carcinoma (n = 1). A venovenous extracorporeal membrane oxygenation was used in the 6 last cases. The mean length of resection was 81 mm [50-120 mm]. There was no 30-day postoperative mortality. A complete resection (R0) was achieved in 11 patients. The main late complications consisted of tracheal granulomas related to the stent and requiring repeated bronchoscopies (n = 9), pneumonia (n = 3), airway infection (n = 1), bronchoesophageal fistula (n = 1), mechanical stent obstruction requiring change (n = 2), and mediastinitis treated by antibiotics, drainage, and omentoplasty (n = 1). With a maximal follow-up of 3 years and 7 months, cancer recurrence was observed in 2 patients. All patients were alive at last follow-up except 2 (84.6%). Conclusions: Airway replacement using stented CAA represents a feasible and promising solution for extensive tracheal cancer.

Bridging Molecular and Clinical Sciences to Achieve the Best Treatment of Enterococcus faecalis Endocarditis.

Enterococcus faecalis (E. faecalis) is a commensal bacterium that causes various infections in surgical sites, the urinary tract, and blood. The bacterium is becoming a significant concern because it tends to affect the elderly population, which has a high prevalence of undiagnosed degenerative valvular disease and is often subjected to invasive procedures and implanted medical devices. The bacterium's actions are influenced by specific characteristics like pili activity and biofilm formation. This resistance significantly impedes the effectiveness of numerous antibiotic therapies, particularly in cases of endocarditis. While current guidelines recommend antimicrobial therapy, the emergence of resistant strains has introduced complexity in managing these patients, especially with the increasing use of transcatheter therapies for those who are not suitable for surgery. Presentations of the condition are often varied and associated with generalised symptoms, which may pose a diagnostic challenge. We share our encounter with a case study that concerns an octogenarian who had a TAVI valve and developed endocarditis. We also conducted a literature review to identify the essential treatment algorithms for such cases.

Bilateral lung transplant with pulmonary artery reconstruction using donor aorta for pulmonary hypertension with a giant pulmonary arterial aneurysm.

OBJECTIVES: Standard bilateral lung transplantation (BLT) is not feasible for patients with pulmonary arterial hypertension (PAH) complicated with a giant pulmonary arterial aneurysm (PAA). This study aimed to describe the outcomes of BLT with pulmonary artery reconstruction (PAR) using donor aorta for such patients. METHODS: This is a retrospective single-centre study reviewing PAH patients with a PAA who received BLT with PAR using donor aorta from January 2010 through December 2020. We compared the characteristics and short- and long-term outcomes of recipients receiving PAR (PAR group) with those who had no PAA and received standard BLT (non-PAR group). RESULTS: Nineteen adult PAH patients underwent cadaveric lung transplantation during the study period. Among them, 5 patients with a giant PAA (median pulmonary artery trunk diameter, 69.9 mm) underwent BLT with PAR using donor aorta and the others received standard BLT. Although the operation time tended to be longer in the PAR group compared with the non-PAR group (1239 vs 958 mins, P = 0.087), 90-day mortality (PAR group: 0% vs non-PAR group: 14.3%, P > 0.99), and 5-year survival rate (PAR group: 100% vs non-PAR group: 85.7%, P = 0.74) was comparable between the groups. No dilatation, constriction or infection of the aortic grafts were recorded during the study period with a median follow-up time of 94 months in the PAR group. CONCLUSIONS: Lung transplantation with PAR using donor aorta is a valid surgical option for PAH patients complicated with a giant PAA.

Application of aortic allograft in trachea transplantation.

BACKGROUND: The use of tracheal implants for tracheal reconstruction remains a challenge in thoracic medicine due to the complex structure of the trachea in mammalian organisms, including smooth muscles, cartilage, mucosa, blood vessels, cilia, and other tissues, and the difficulty in achieving tracheal regeneration using implants from either allografts or synthetic biomaterials. METHODS: This project used the Lee-Sung strain pig, a swine breed local to Taiwan, as the experimental subject. The aorta of the pig was harvested, decellularized to form the scaffold, and transplanted into the trachea of allogeneic pigs together with growth factors. Postoperative physiological function and tissue changes were observed. The postoperative physiological parameters of the LSP were monitored, and they were sacrificed after a certain period to observe the pathological changes in the tracheal epithelial cells and cartilages. RESULTS: Overall, six LSP tracheal transplantations were performed between March 4, 2020, and March 10, 2021. These included aortic patch anastomosis for pig 1 and aortic segmental anastomosis for pigs 2-6. The shortest and longest survival periods were 1 day and 147 days, respectively. Excluding the pig that survived for only 1 day due to a ruptured graft anastomosis, all other subjects survived for over 1 month on average. CONCLUSION: In this study, we grafted a decellularized porcine aorta into a recipient pig with a tracheal defect. We found cryopreservation of the allogeneic aorta transplantation was a feasible and safe method for the management of airway disease, and immunosuppressants were unnecessary during the treatment course.

Successful Total Tracheal Replacement by Cryopreserved Aortic Allograft in a Patient Post-COVID-19 Infection.

This is the first report to our knowledge of a successful total tracheal replacement in a post-COVID-19 patient by cryopreserved aortic allograft. The graft was anastomosed to the cricoid and carina; a silicon stent was inserted to ensure patency. The patient was extubated on the operative table and was immediately able to breathe, speak, and swallow. No immunosuppression was administered. Three weeks after surgery, the patient was discharged from hospital in excellent health, and was able to resume his normal lifestyle, work, and activity as an amateur cyclist. Two months after surgery, the patient assumes aerosol with saline solution three times per day and no other therapy; routine bronchoscopy to clear secretions is no longer needed.

Feasibility of modified endarterectomized aortic allograft for middle hepatic vein reconstruction in living donor liver transplantation: A retrospective cohort study.

BACKGROUND: Cryopreserved allografts and artificial vascular grafts were introduced to meet the increasing demand for adequate vascular substitutes for middle hepatic vein (MHV) reconstruction during living donor liver transplantation (LDLT). This study evaluated patency outcomes after engraftment of a modified endarterectomized aortic allograft (MEAA) without any additional patches. METHODS: This retrospective double-arm study was conducted in single tertiary referral center between January 2015 and July 2018. Of 1,047 adult patients who underwent single-graft LDLT with a modified right lobe (MRL), 111 patients who received grafts with MHV reconstruction using MEAA were selected. The control group comprised 434 patients who underwent MHV reconstruction using iliac vein allografts. The main outcome measure was the short-term patency of the MEAA. The secondary outcome was the incidence of graft-associated complications. RESULTS: Clinically significant MHV stenoses requiring stenting occurred in 3 patients (2.7%) in the MEAA group and in 17 patients (3.9%) in the iliac vein group (P = 0.778). Three-month and one-year patency rates on Doppler ultrasonography and computed tomography were 88.5% and 54.0%, respectively, in the MEAA group and 84.0% and 42.2%, respectively, in the iliac vein group, indicating the superior patency outcomes with MEAA (P = 0.017). CONCLUSIONS: MHV reconstruction using MEAA during LDLT of a MRL graft is technically simple, achieves clinical outcomes comparable to iliac vein grafts, and is effective in expanding the allograft vessel pool for LDLT.

Lanthanum carbonate, a phosphate binder, inhibits calcification of implanted aortic allografts in a rat model.

OBJECTIVES: Calcification is one of the major postoperative problems after aortic allograft implantation. We hypothesized that phosphate binders, lanthanum carbonate and calcium carbonate inhibit calcification of implanted aortic allografts and verified this hypothesis using a rat model. METHODS: Aortas were harvested from 4-week-old Brown Norway rats and implanted into the subdermal space of 4-week-old Lewis rats. Twenty-seven recipient Lewis rats were divided into Group N, Group L, and Group C (9 rats per group), which were fed a normal diet, a normal diet containing 3% lanthanum carbonate, and a normal diet containing 3% calcium carbonate, respectively. Implanted aortic allografts were explanted 2 weeks later. Calcification of aortic allografts was evaluated using von Kossa staining and calcium content assay. Calcification score was defined in von Kossa staining as 0 (none), 1 (mild), 2 (moderate), and 3 (severe). Serum calcium and phosphorus levels at euthanasia were measured. RESULTS: Calcification scores were 2.6, 1.2, and 0.8, and calcium content was 48.9, 15.8, and 8.9 mg/dry·g, in Groups N, L, and C, respectively. Calcification was significantly reduced in Groups L and C. Serum calcium level was 11.5, 12.2, and 13.5 mg/dl, and serum phosphorus level was 15.4, 12.5, and 11.7 mg/dl, in Groups N, L, and C, respectively. Serum calcium level in Group C was significantly higher than in the other two groups. CONCLUSIONS: Lanthanum carbonate and calcium carbonate significantly reduced calcification of implanted aortic allografts in young rats. Although calcium carbonate induced hypercalcemia, lanthanum carbonate has significant potential to inhibit calcification of implanted aortic allografts.

Aortic allografts: final destination?-a summary of clinical tracheal substitutes.

The patient population in desperate need for an airway substitute are individuals with long segment tracheal defects that are considered, technically, inoperable. Regardless of the underlying etiology, benign or malignant growing processes, this patient category enters a palliative setting or require tracheal transplantation. Different airway substitutes have been categorized by Grillo as follows; tracheal transplantation, autogenous tissue, non-viable tissue, tissue-engineering and foreign materials. These fields have been explored in the past in animal models and in clinical patients. Research on airway replacement has been exposed to a level of controversies in the past years. The field has been turbulent and apocryphal. In particular, the area of tissue-engineering using stem cells has suffered from a major set-back leaving scientists, clinicians and ethical committees skeptical. Recently, a hopeful study emerged using aortic allografts as tracheal substitutes in patients with airway defects. The initial results seem promising and reliable. The developments of the field at this point seem striking and hopeful. The focus of this review is to shed light on developments in the field of aortic allografts as substitute for tracheal replacement.

Long-term outcome of cryopreserved allograft for aortic valve replacement.

OBJECTIVE: The most efficient surgical approach to severe aortic valve disease in the young adult is still debated: cryopreserved aortic allograft offers excellent hemodynamic and avoid anticoagulation, but long-term durability is influenced by structural valve deterioration (SVD). This study aimed to describe long-term results of aortic allografts and to identify factors influencing long-term durability. METHODS: From January 1993 to August 2010, 210 patients underwent aortic allograft replacement via the free-hand subcoronary implantation technique (N = 55) or root replacement with coronary reimplantation (N = 155). Clinic and echocardiographic follow-up was updated to April 2016. RESULTS: Overall mortality and cardiac mortality occurred in 80 (38.1%) and 64 (30.5%) patients, respectively. Reoperation was required in 69 cases (32.8%), whereas SVD required reoperation in 57 cases (27.1%). No early endocarditis occurred, whereas late endocarditis occurred in 4 patients. The free-hand technique seems to be associated with improved left ventricular remodeling compared with the root-replacement technique, and smaller allograft size represents a predictor of reoperation independently on the surgical technique used. In the overall population, there were 44 women of childbearing age, and 37 patients remained pregnant during the follow-up of the study. No differences were found in the clinical outcomes among women who had children and who did not. CONCLUSIONS: Cryopreserved allograft is a valid option, especially in complex infective endocarditis and in women of childbearing age. A careful choice of allograft size and implantation technique can reduce the risk of SVD.

Surgical treatment of infective endocarditis with aortic and tricuspid valve involvement using cryopreserved aortic and mitral valve allografts.

Surgical treatment of infective and prosthetic endocarditis using allografts gives good results. Aortic allograft implantation is a common technique, while tricuspid valve replacement with a mitral allograft is very rare. Multiple valve disease in case of infective endocarditis is a surgical challenge as such patients are usually in a grave condition and results of surgical treatment are often unsatisfactory. In this article we describe a clinical case of successful surgical treatment in a patient with active infective endocarditis of aortic and tricuspid valve, complicated by an aortic-right ventricular fistula. The aortic valve and ascending aorta were replaced with a cryopreserved aortic allograft; the tricuspid valve was replaced with a cryopreserved mitral allograft.

Infectious aortitis in a liver transplant recipient.

The development of an abdominal aortic aneurysm secondary to infectious aortitis following solid organ transplantation is a rare event that in the absence of surgical intervention, can lead to uncontrolled sepsis, catastrophic hemorrhage and death. Arterial allografts have been a viable surgical option for the past 30 years, although operative modalities have undergone a paradigm shift in recent years. We describe the first case in the literature of a liver transplant recipient who developed an infrarenal aortic aneurysm secondary to Salmonella bacteraemia, which was treated successfully with aortic allograft transplantation.

Acute regeneration and chronic acellular transformation of rabbit cryopreserved aortic allografts.

An analysis of rabbit cryopreserved aortic allografts excised on postoperative days (POD) 2, 5, 11, 60, 210, 360, and 720, as well as controls that were untransplanted native aortas and cryopreserved aortas, was performed. On POD2, the number of medial smooth muscle cells in the allografts was reduced to approximately 50%. Ki-67 analysis revealed that medial smooth muscle cells in the allografts proliferated from the 2nd day. By the 11th day, their proliferation ceased and the number of medial smooth muscle cells was restored to almost at the same level as in the controls. Polymorphic microsatellite DNA marker analysis disclosed that the restored medial smooth muscle cells were of donor origin. From 7 months through 2 years, the media of cryopreserved aortic allografts were transformed into acellular structures, in which the elastic fibers were preserved. On the other hand, newly accumulated smooth muscle cells were observed in the adventitia just outside of acellular media after 7 months. In some cases, scattered lamellar calcium deposition was observed in the same regions. This study presents a comprehensive documentation of regeneration and acellular transformation in cryopreserved aortic allografts based on short and long-term analysis.