Monomeric glutaraldehyde fixation and amino acid detoxification of decellularized bovine pericardium for production of biocompatible tissue with tissue-guided regenerative potential.

The effect of monomeric glutaraldehyde fixation and amino acid detoxification on biocompatibility and tissue-guided regenerative potential of decellularized bovine pericardium was evaluated. The degree of cross-linking, porosity, enzymatic degradation, alpha-galactosyl content, the efficacy of detoxification, and cytotoxicity towards human epithelial cells were assessed. Tissue was subcutaneously implanted for eight weeks in male juvenile Sprague-Dawley rats, and mechanical properties, host cell infiltration, and calcification were evaluated. Three groups were compared i) decellularized tissue, ii) decellularized, monomeric glutaraldehyde fixed and amino acid detoxified tissue, and iii) commercial glutaraldehyde fixed non-decellularized tissue (Glycar®) (n = 6 rats per group). The fixation process gave a high degree of cross-linking (>85%), and was resistant to enzymatic degradation, with no significant effect on porosity. The detoxification process was effective, and the tissue was not toxic to mammalian cells in vitro. Tissue from both decellularized groups had significantly higher (p < 0.05) porosity and host cell infiltration in vivo. The process mitigated calcification. A non-significant decrease in the alpha-galactosyl content was observed, which increased when including the alpha-galactosidase enzyme. Mechanical properties were maintained. The fixation and detoxification process adequately removes free aldehyde groups and reduces toxicity, preventing enzymatic degradation and allowing for host cell infiltration while mitigating calcification and retaining the mechanical properties of the tissue. This process can be considered for processing decellularized bovine pericardium with tissue-guided regeneration potential for use in cardiovascular bioprostheses; however, methods of further reducing antigenicity, such as the use of enzymes, should be investigated.

Minimally invasive direct coronary artery bypass and percutaneous coronary intervention followed by transcatheter aortic valve implantation: A promising concept in high-risk octogenarians.

Objectives: In this article, we present our initial clinical experience with staged minimally invasive direct coronary bypass (MIDCAB), percutaneous coronary intervention (PCI), and transcatheter aortic valve implantation (TAVI) in high-risk octogenarians (Hybrid). Background: The use of percutaneous techniques for managing structural heart diseases, especially in elderly high-risk patients, has revolutionized the treatment of structural heart diseases. These procedures are present predominantly being offered as isolated interventions. The feasibility, clinical benefit, and outcomes of combining these techniques with MIDCAB have not been sufficiently explored and have subsequently been underreported in the contemporary literature. Methods: Four consecutive octogenarians with severe aortic stenosis (AS) and complex coronary artery disease (CAD) that were at high risk for conventional surgery with extracorporeal circulation (ECC) were discussed in our Multidisciplinary Heart Team (MDH). Our MDH consisted of an interventional cardiologist, cardiac surgeon, and cardiac anesthesiologist. A hybrid approach with the alternative strategy comprising of MIDCAB, PCI, and TAVI in a staged fashion was agreed on. All 4 patients had both PCI/stenting and MIDCAB prior to deployment of the TAVI-prosthesis. Results: From January 2019 to December 2020, 4 consecutive patients aged between 83 and 85 (3 male/1 female) years were scheduled for MIDCAB/PCI followed by percutaneous treatment of severe symptomatic AS. Intraoperatively, one patient was converted to full sternotomy, and surgery was performed by off-pump coronary artery bypass grafting. The overall procedural success rate was 100% in all 4 patients with resolution of their initial presenting cardiopulmonary symptoms. There were no severe complications associated with all hybrid procedures. There was no 30-day mortality in all patients. All patients were discharged home with a median hospital stay ranging between 9 and 25 days. All patients have since then been followed-up regularly. There was one noncardiac-related mortality at 6-months postsurgery. All other patients were well at 1-year follow-up with improved New York Heart Association Class II. Conclusions: In a selected group of elderly, high prohibitive risk patients with CAD and severe symptomatic AS, a staged approach with MIDCAB and PCI followed by TAVI can be safely performed with excellent outcomes. We advocate a MDH-based preliminary evaluation of this patient cohort in selecting suitable patients and appropriate timing of each stage of the hybrid procedure.

Sarcomeric network analysis of ex vivo cultivated human atrial appendage tissue using super-resolution microscopy.

Investigating native human cardiac tissue with preserved 3D macro- and microarchitecture is fundamental for clinical and basic research. Unfortunately, the low accessibility of the human myocardium continues to limit scientific progress. To overcome this issue, utilizing atrial appendages of the human heart may become highly beneficial. Atrial appendages are often removed during open-heart surgery and can be preserved ex vivo as living tissue with varying durability depending on the culture method. In this study, we prepared living thin myocardial slices from left atrial appendages that were cultured using an air-liquid interface system for overall 10 days. Metabolic activity of the cultured slices was assessed using a conventional methyl thiazolyl tetrazolium (MTT) assay. To monitor the structural integrity of cardiomyocytes within the tissue, we implemented our recently described super-resolution microscopy approach that allows both qualitative and quantitative in-depth evaluation of sarcomere network based on parameters such as overall sarcomere content, filament size and orientation. Additionally, expression of mRNAs coding for key structural and functional proteins was analyzed by real-time reverse transcription polymerase chain reaction (qRT-PCR). Our findings demonstrate highly significant disassembly of contractile apparatus represented by degradation of [Formula: see text]-actinin filaments detected after three days in culture, while metabolic activity was constantly rising and remained high for up to seven days. However, gene expression of crucial cardiac markers strongly decreased after the first day in culture indicating an early destructive response to ex vivo conditions. Therefore, we suggest static cultivation of living myocardial slices derived from left atrial appendage and prepared according to our protocol only for short-termed experiments (e.g. medicinal drug testing), while introduction of electro-mechanical stimulation protocols may offer the possibility for long-term integrity of such constructs.

ECG-gated MR angiography at 3T for follow-up after surgery involving the ascending aorta.

We aimed to evaluate electrocardiogram (ECG)-gated MR angiography (MRA) in the follow-up after surgery involving the ascending aorta regarding technical feasibility, image quality, spectrum of findings, and their implications for clinical management. We retrospectively analyzed a cohort of 19 patients (median age 59 years, range 38-79 years), who underwent MRA for follow-up imaging after surgery involving the ascending aorta. Our magnetic resonance imaging protocol consisted of a time-resolved, non-ECG-gated MRA and an ECG-gated MRA performed at 3T. Median examination duration was 25 minutes (range 11-41 minutes). All examinations were assessed by 2 readers in consensus for image quality on a 5-point scale ranging from 1 (non-diagnostic) to 5 (excellent). MRA examinations and patient charts were analyzed for diagnostic findings and their consequences for further management. Subjective image quality was rated as "sufficient" (score 3.1 ±â€…1.1) for the aortic root and as "good" to "excellent" for the ascending aorta (score 4.5 ±â€…0.7), aortic arch (4.5 ±â€…0.7), supra-aortic branches (4.5 ±â€…0.6) and descending aorta (4.6 ±â€…0.7). Abnormal findings were seen in 6 patients (32%) including progressive diameter of remaining aneurysm or dissection (3 patients, 16%) and suture aneurysms (3 patients, 16%). In all 6 of these patients, abnormal findings at MRA had consequences for clinical management. ECG-gated MR angiography at 3T yields good image quality for post-operative surveillance after aortic surgery involving the ascending aorta. This technique may serve as an alternative to computed tomography particularly in younger patients with repeated follow-up.

Impact of Three Different Processing Techniques on the Strength and Structure of Juvenile Ovine Pulmonary Homografts.

Homografts are routinely stored by cryopreservation; however, donor cells and remnants contribute to immunogenicity. Although decellularization strategies can address immunogenicity, additional fixation might be required to maintain strength. This study investigated the effect of cryopreservation, decellularization, and decellularization with additional glutaraldhyde fixation on the strength and structure of ovine pulmonary homografts harvested 48 h post-mortem. Cells and cellular remnants were present for the cryopreserved group, while the decellularized groups were acellular. The decellularized group had large interfibrillar spaces in the extracellular matrix with uniform collagen distribution, while the additional fixation led to the collagen network becoming dense and compacted. The collagen of the cryopreserved group was collapsed and appeared disrupted and fractured. There were no significant differences in strength and elasticity between the groups. Compared to cryopreservation, decellularization without fixation can be considered an alternative processing technique to maintain a well-organized collagen matrix and tissue strength of homografts.

Introduction of the Rapid Deployment Aortic Valve System Use in Elderly Patients With Endocarditis.

Introduction: The rapid-deployment valve system (RDVS) was introduced to facility minimally invasive aortic valve replacement. In this study we evaluate the potential benefits of RDVS in elderly high-risk patients with endocarditis of the aortic valve. Materials and Methods: Since the introduction of RDVS in our institution in December 2017 through October 2021, EDWARDS INTUITY rapid-deployment prosthesis (Model 8300A, Edwards Lifesciences, Irvine, CA, USA) has been implanted in a total of 115 patients for different indications by a single surgeon. Out of one-hundred and fifteen cases of RDVS implantation, seven patients with a median age of 77 yrs. (range 62-84yrs.), suffered from active infective endocarditis of the aortic valve. The median EuroSCORE II of these highly selected patient cohort was 77% (range 19-80%). Patient data were evaluated perioperatively including intra-operative data as well as in-hospital morbidity/mortality and follow-up after discharge from hospital. Results: Three patients underwent previous cardiac surgery. Concomitant procedures were performed in six patients including, ascending aorta replacement (n = 3), mitral valve repair (n = 1), pulmonary valve replacement (n = 1), bypass surgery (n = 1), left atrial appendix resection (n = 1) and anterior mitral valve repair (n = 1). Median aortic cross-clamp and cardiopulmonary bypass time was 56 min (range 29-122 min) and 81 min (range 45-162 min.), respectively. Post-operative complications in these elderly high-risk patients were atrial fibrillation (n = 3) and re-exploration for pericardial effusion (n = 1). One pacemaker implantation was required on postoperative day 6 due to sick sinus syndrome. There was one in-hospital death (14%) and one during follow-up (14%). Conclusion: Rapid-deployment aortic valve system seems to be a viable option with acceptable morbidity and mortality in elderly high-risk patients with active infective endocarditis of the aortic valve.

Management of Pulmonary Artery Synovial Sarcoma: The 3-Step Surgical Approach.

Primary pulmonary artery sarcoma is an uncommon neoplasm. Given its clinical and radiographic resemblance to pulmonary embolism, initial diagnostic steps may be complicated, leading to delay in diagnosis. This report presents the case of a 52-year-old-woman who was admitted with pulmonary embolism. She underwent pulmonary embolectomy, and histopathologic examination revealed synovial sarcoma.

Surgery for Valvular and Nonvalvular Papillary Fibroelastomas.

Papillary fibroelastomas (PFE) are benign neoplasms, mostly located on valvular surfaces with high embolic potential. This study presents a 27-year single institutional experience on surgical treatment of PFE in an adult patient- cohort with long-term follow-up. This study was approved by the institutional review board. Date and number of IRB approval: 11/23/2017, Institutional Review Board approval number A2014-0149. The need for individual patient consent was waived. We retrospectively evaluated all patients who underwent cardiac surgery for suspected space-occupying lesions in the observation period between June 1991 and June 2018 at our hospital. Clinicopathological features, imaging characteristics, surgical procedures and disease outcome were analyzed. 120 patients were diagnosed with various primary/secondary cardiac tumors and histology confirmed 21 PFEs were found in 16 patients. There was no significant age difference between patients with valvular vs nonvalvular PFEs (P = 0.26). Valvular lesions were found in aortic valve (n = 6), mitral valve (n = 2) and tricuspid valve (n = 1). Nonvalvular PFEs were found in right atrium (n = 2), left ventricle (n = 2), left atrial appendage (n = 2) and aortic wall (n = 1). Valvular lesions were significantly smaller in size compared to non-valvular lesions (P = 0.0013). Left-side PFEs were associated with a high embolization episodes (10/13 patients, 77%) not related to the size. One patient died in-hospital. All other patients were discharged out of the hospital postoperative. Follow-up was performed regularly for a median of 2.8 years (range 0.1-11 years) postoperative. Nonvalvular PFE tended to be larger in size and at least when located on the left sided heart had equally high propensity to embolize compared to valvular PFE. We strongly advocate surgical excision in all left-sided PFE.

Comparison of the function and structural integrity of cryopreserved pulmonary homografts versus decellularized pulmonary homografts after 180 days implantation in the juvenile ovine model.

Homograft availability and durability remain big challenges. Increasing the post-mortem ischaemic harvesting time beyond 24 h increases the potential donor pool. Cryopreservation, routinely used to preserve homografts, damages the extracellular matrix (ECM), contributing to valve degeneration. Decellularization might preserve the ECM, promoting host-cell infiltration and contributing towards better clinical outcomes. This study compared the performance of cryopreserved versus decellularized pulmonary homografts in the right ventricle outflow tract (RVOT) of a juvenile ovine model. Homografts (n = 10) were harvested from juvenile sheep, subjected to 48 h post-mortem cold ischaemia, cryopreserved or decellularized and implanted in the RVOT of juvenile sheep for 180 days. Valve performance was monitored echocardiographically. Explanted leaflet and wall tissue evaluated histologically, on electron microscopical appearance, mechanical properties and calcium content. In both groups the annulus diameter increased. Cryopreserved homografts developed significant (¾) pulmonary regurgitation, with trivial regurgitation (») in the decellularized group. Macroscopically, explanted cryopreserved valve leaflets retracted and thickened while decellularized leaflets remained thin and pliable with good coaptation. Cryopreserved leaflets and walls demonstrated loss of interstitial cells with collapsed collagen, and decellularized scaffolds extensive, uniform ingrowth of host-cells with an intact collagen network. Calcific deposits were shown only in leaflets and walls of cryopreserved explants. Young fibroblasts, with vacuoles and rough endoplasmic reticulum in the cytoplasm, repopulated the leaflets and walls of decellularized scaffolds. Young's modulus of wall tissue in both groups increased significantly. Cryopreserved valves deteriorate over time due to loss of cellularity and calcification, while decellularized scaffolds demonstrated host-cell repopulation, structural maintenance, tissue remodelling and growth potential.

Hybrid approach for percutaneous mitral valve repair (MitraClip®) followed by minimally invasive direct coronary artery bypass (MIDCAB) in a patient with a high risk constellation.

BACKGROUND: We present a 76-year-old poly-morbid male patient suffering from severe ischemic mitral valve regurgitation. A hybrid approach was suggested by the heart team to treat his multifaceted cardiac pathologies. METHODS: At first percutaneous mitral valve repair with the mitraclip device was performed to reduce surgical risk. This was then followed by minimally invasive direct coronary artery bypass (MIDCAB). RESULTS: At day 20 Post mitraclip intervention the patient suffered gastrointestinal bleeding which needed argon plasma coagulation (APC)-therapy and multiple blood transfusions. Stage II of the hybrid procedure was executed on post-intervention day 34 by minimally invasive direct coronary artery bypass (MIDCAB) to left anterior descending artery (LAD). Seven days later the patient was discharged. Up to two years of follow-up, the patient is in stable condition, without recurrent cardiac symptoms. CONCLUSION: Hybrid approach of percutaneous mitral valve repair followed by MIDCAB is an effective minimally invasive treatment for severe ischemic mitral valve regurgitation and coronary artery disease.

Papillary Fibroelastoma in Differential Diagnosis of Left Atrial Appendage Masses.

Papillary fibroelastomas are benign tumors that usually originate from cardiac valves but may have other endocardial origins. We report the cases of 2 patients in whom left atrial appendage masses were initially diagnosed as thrombus. They were treated for embolic stroke and their symptoms resolved; however, their left atrial appendage masses did not regress. After surgery, histologic analysis of the resected masses revealed papillary fibroelastoma in both cases. We discuss the diagnostic and therapeutic dilemmas encountered in patients with papillary fibroelastomas and cardiac masses other than thrombus.

Aortic valve and coronary artery bypass surgery in a patient with factor VII deficiency.

Congenital factor VII (FVII) deficiency is a rare bleeding disorder (RBD) with phenotypes ranging from asymptomatic state to life threatening bleeding episodes. There is no established recommendation for the perioperative management of patients scheduled for cardiac surgery. We have described the perioperative management of a patient with FVII deficiency treated for aortic valve stenosis, coronary artery disease, and atrial fibrillation. Balancing perioperative bleeding risk and risks of thrombotic events thereafter in such patients is difficult and requires a multidisciplinary approach.

Management of superficial and deep surgical site infection: an international multidisciplinary consensus.

Surgical site infections represent a considerable burden for healthcare systems. To obtain a consensus on the impact and future clinical and economic needs regarding SSI management in an era of multidrug resistance. A modified Delphi method was used to obtain consensus among experts from five European countries. The Delphi questionnaire was assembled by a steering committee, verified by a panel of experts and administered to 90 experts in 8 different surgical specialities (Abdominal, Cancer, Cardiac, General surgery, Orthopaedic, Thoracic, Transplant and Vascular and three other specialities (infectious disease, internal medicine microbiology). Respondents (n = 52) reached consensus on 62/73 items including that resistant pathogens are an increasing matter of concern and increase both treatment complexity and the length of hospital stay. There was strong positive consensus on the cost-effectiveness of early discharge (ED) programs, improvement of quality of life with ED and association between increased length of stay and economic burden to the hospital. However, established ED protocols were not widely available in their hospitals. Respondents expressed a positive consensus on the usefulness of antibiotics that allow ED. Surgeons are aware of their responsibility in an interdisciplinary team for the treatment of SSI, and of the impact of multidrug-resistant bacteria in the context of SSI. Reducing the length of hospital stays by applying ED protocols and implementing new treatment alternatives is crucial to reduce harm to patients and costs for the hospital.

Surgical revision after percutaneous mitral valve repair by edge-to-edge device in high-risk patients.

BACKGROUND: Patients scheduled for surgery after unsuccessful MitraClip® intervention present increasingly with multiple comorbidities, and they are often referred to the heart team to suggest the most appropriate intervention. The publication of successful results of initial patient cohorts treated with the MitraClip device has resulted in recruitment of more seriously ill patients, who otherwise would have been denied catheter-based/surgical treatment. There has been increasingly reports on conventional surgery after failed mitral valve repair with the MitraClip device. However, data on such procedures remain scarce and mostly focused on individual case studies. The inevitable increase in use of MitraClip, however, will raise the number of patients in need of surgery post MitraClip, making it imperative for surgeons to understand challenges and outcome data related with surgery in this patient cohort. We present our long-term institutional experience with surgery after MitraClip intervention in highest risk patients. METHODS: Eighteen patients underwent surgery of the mitral valve at our Institution between January 2015 and June 2020. These patients developed recurrent mitral regurgitation grade more than 2° at various intervals after MitraClip. Mitral valve repair was performed where possible and gross examination Valve/MitraClip were intra-operatively documented. Implanted MitraClip devices were analyzed histopathologically to evaluate the healing process and rule out inflammation. Regular patient follow-up was performed. RESULTS: Mean patient age was 74 (±9 years) and MitraClip implantation was performed at various tertiary institutions. Sixteen out of eighteen (16/18) patients received mitral valve replacement, whereas the remaining two patients received mitral valve repair and extracorporal membrane oxygenation, respectively. Four patients died of sepsis and intractable multi organ failure in-hospital. The remaining patients were discharged alive out of hospital to different rehabilitation centers. Follow-up was complete in all patients. CONCLUSIONS: Surgery is demanding when patients require surgery for persistent or recurrent mitral regurgitation after MitraClip therapy and can be successfully implemented as a possible therapy option for selective cases as an interdisciplinary approach despite calculated high perioperative mortality risk. These patients should not be denied surgery outright.

Calculated initial parenteral treatment of bacterial infections: Bacterial endocarditis.

This is the twelfth chapter of the guideline "Calculated initial parenteral treatment of bacterial infections in adults - update 2018" in the 2nd updated version. The German guideline by the Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) has been translated to address an international audience. The bacterial endocarditis is characterised by a constant incidence but a shift in the patient population due to the use of prosthetic heart valves and foreign materials like pacemakers and the increasing application of invasive medical procedures. This is linked to a change in the predominant infecting organisms towards staphylococci. This chapter gives recommendations for the interdisciplinary management of infective endocarditis from the diagnostic workup over prevention to therapy with a focus on antibiotic therapy.

Calculated parenteral initial treatment of bacterial infections: Introduction and antibiotics.

This is the first chapter of the guideline "Calculated initial parenteral treatment of bacterial infections in adults - update 2018" in the 2nd updated version. The German guideline by the Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) has been translated to address an international audience. This guideline is a revision of the recommendations published in 2010, taking into account recent substances and studies. As with previous revisions, the current situation of pathogen resistance and the results of new clinical trials are considered. The results are the present recommendations for parenteral calculated initial therapy of bacterial infections in adults. If several treatment options are mentioned, they are not always equivalent in their spectrum of microbiological activity. Therapeutic alternatives offer the opportunity to consider pathogen epidemiology, to avoid antibiotic intolerances or to escalate or de-escalate treatment in a manner suited to the situation. This article describes the different therapy options.

Synergy in a detergent combination results in superior decellularized bovine pericardial extracellular matrix scaffolds.

Decellularization involves removal of cellular material from tissue which results in a scaffold material consisting of only the extra cellular matrix (ECM). The effect of each individual decellularizing detergent on the final ECM scaffold and how that may differ from the combined use of these detergents is currently a gap in decellularization methodologies. This study evaluates the hypothesis that a synergistic effect exists when commonly used decellularization detergents are combined. This was evaluated with regard to decellularization efficiency, tissue strength, and collagen structure. Bovine pericardium was decellularized using a combination of 0.5% sodium dodecyl sulfate (SDS), 1% sodium deoxycholate (SDC) and 1% TritonX-100, and compared to the use of each detergent individually. The combined detergent decellularization protocol showed effective decellularization (p = .004), with minimal effects on tissue strength (p = .21) and structure (p = .21). Use of detergents individually, resulted in detrimental effects on tissue structure and integrity or ineffective decellularization. This study shows a synergistic relationship between SDS, SDC and TritonX-100 when combined at specific concentrations. The use of detergents in combination instead of individually appears to be superior, as it results in less ECM damage and improved decellularization effectivity.

Synergizing Antegrade Endoscopic with Bridging Vein Harvesting for Improvement of Great Saphenous Vein Graft Quality from the Lower Leg.

Antegrade endoscopic harvesting of autografts for bypass grafting may be an optimal strategy addressing excellent graft quality and reduced post-operative wound complications. This standardized protocol for antegrade endoscopic vein harvesting (EVH) from the lower leg has the potential to be introduced to routine coronary artery bypass grafting (CABG). Patients undergoing CABG surgery are positioned on a surgical table with two additional foam rollers below the extended legs, enabling antegrade EVH from the lower leg. Following minimally invasive surgical access through a bridging vein harvest technique, an endoscopic optical dissector is inserted antegrade into the wound. The main vessel and side branches are dissected under continuous optical control of vein quality status and the working channel. After, an endoscopic optical retractor is inserted with an internal bipolar electrocoagulation device for precise, safe, and tissue-protective interruption of side branches. After release of the vein, the vessel is cut off at the proximal and distal ends under optical control, retrieved from the wound, then cannulated and flushed with heparinized saline. Finally, all side branches of the vein graft are double-clipped. Vascular histology is analyzed in a randomized selection of vein samples. After applying this standardized EVH protocol, the learning curve was shown to be steep, and graft quality was sufficient for coronary artery bypass grafting in every case. There was no conversion to surgical harvesting and low risks for tissue damage and bleeding. Leg positioning and synergizing EVH with bridging vein harvesting improved procedural success and vein graft quality. In our hands, antegrade EVH from the lower leg was feasible, demonstrating straightforward graft dissection as well as adequate macroscopic and microscopic graft quality with preserved endothelial integrity. In conclusion, the introduced technique is safe, shows excellent vein autograft quality, and illustrates feasibility for elective and urgent isolated CABG and combined CABG scenarios.

Cadaver donation: structural integrity of pulmonary homografts harvested 48 h post mortem in the juvenile ovine model.

Cryopreserved pulmonary homograft (CPH) implantation remains the gold standard for reconstruction of the right ventricular outflow tract (RVOT). Harvesting homografts < 24-h post mortem is the international norm, thereby largely excluding cadaveric donors. This study examines the structural integrity and stability of ovine pulmonary homografts harvested after a 48-h post mortem period, cryopreserved and then implanted for up to 180 days. Fifteen ovine pulmonary homografts were harvested 48-h post mortem and cryopreserved. Five CPH served as a control group (group 1; n = 5). CPH were implanted in the RVOT of juvenile sheep and explanted after 14 days (group 2; n = 5) and 180 days (group 3; n = 5). Leaflet integrity was evaluated by strength analysis, using tensile strength (TS), Young's modulus (YM) and thermal denaturation temperature (Td), and morphology, including haematoxylin and eosin (H&E), Picrosirius red staining, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and von Kossa stains. Echocardiography confirmed normal function in all implants. In explants, no reduction in TS, YM or Td could be demonstrated and H&E showed mostly acellular leaflet tissue with no difference on Picrosirius red. TEM demonstrated consistent collagen disruption after cryopreservation in all three groups, with no morphological deterioration during the study period. von Kossa stains showed mild calcification in group 3. No deterioration of structural integrity could be demonstrated using strength or morphological evaluations between the controls and implant groups over the study period. Extending the post mortem harvesting time of homografts beyond 24 h did not appear to negatively affect the long-term performance of such transplanted valves in this study.