Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection results in dysregulated inflammatory and coagulation pathways that drive immunothrombosis and contribute to adverse clinical outcomes. While individual cytokines and endothelial biomarkers have been associated with disease severity and mortality, the prognostic relevance of combined inflammatory and endothelial signatures remains incompletely characterised. To identify inflammatory cytokines and markers of endothelial activation associated with mortality in patients with severe COVID-19 requiring supplemental oxygen. This retrospective observational study included 73 consecutive adults admitted to a dedicated supplemental oxygen unit with severe COVID-19. Plasma concentrations of IL-1α, IL-1β, IL-6, IL-8, IL-10, TNF-α, von Willebrand factor (VWF) antigen and propeptide, ADAMTS13 antigen and activity, and ADAMTS13 autoantibodies were measured on admission using ELISA-based assays. Associations with mortality were assessed using non-parametric analyses, age-adjusted logistic regression, multivariable logistic regression, and receiver operating characteristic (ROC) curve analysis. Increasing age was independently associated with mortality. After adjustment for age, higher IL-1α concentrations were associated with increased odds of death, whereas a higher IL-6/IL-10 ratio was independently protective. In multivariable models, including non-ratio variables, ADAMTS13 autoantibody levels remained independently associated with mortality. In ratio-based multivariable analysis, both the ADAMTS13 activity/autoantibody ratio and the IL-6/IL-10 ratio were independently protective, while age was no longer significant. IL-10 and ADAMTS13 autoantibodies demonstrated moderate discriminative performance for mortality prediction (AUC ~0.70). A combined biomarker model incorporating IL-1α, IL-8, IL-10, and ADAMTS13 autoantibodies yielded very high predicted mortality probabilities. Our findings highlight IL-1α and ADAMTS13 autoantibodies as independent predictors of mortality in severe COVID-19, reflecting the interplay between inflammatory and endothelial pathways. Biomarker ratios capturing immune and endothelial balance-particularly the ADAMTS13 activity/autoantibody ratio-may enhance risk stratification and support integrated prognostic models.

The Pan-African Society for Cardiothoracic Surgery (PASCaTS) organized the 1st Pan-African Cardiothoracic Surgery Summit on 21 to 24 February 2025 in Accra, Ghana. The summit brought together leading specialists from across Africa, China, Europe, South America and the USA to address the growing burden of cardiovascular disease, to share their vision for the fight against cardiovascular disease, to raise standards in the diagnosis, treatment, and recovery of patients thereby improving procedural safety and clinical outcomes in Africa. The experts agreed on the need for cost effectiveness in cardiac surgery, simulation skills training, an African regional cardiothoracic surgery database, African heart team fellowship programs, and specialized working groups to guide cardiovascular diagnostics and treatments focusing on critical areas such as congenital heart surgery, valve surgery, and coronary artery bypass surgery (CABG) procedures, which are becoming increasingly necessary in Africa due to the rise in cardiovascular emergencies, and finally explore solutions tailored to the continent's unique healthcare challenges. The incentives generated from the summit are formulated as the "2025 Accra Declaration" to serve as roadmaps and implementable guidelines for promoting high-level cardiovascular surgery and reforms in Africa in collaboration with cardiologists and other allied cardiovascular professionals.

BACKGROUND:Pulmonary hypertension (PH) secondary to congenital left-to-right shunts leads to serious consequences in sub-Saharan Africa. This study used various imaging modalities to assess right and left heart dimensions and functions in patients with secondary PH. METHODS:Patients with a mean pulmonary artery pressure ≥ 25 mmHg during right heart catheterisation underwent transthoracic echocardiography, cardiac magnetic resonance imaging (CMRI), and nuclear ventriculography. RESULTS:Seventy-five patients (median age 9.98: 6.01-40.9 years) were included. Right-heart dilation was observed in all, with increased tricuspid valve annular diameter (median z-score 2.44) on echocardiography. Similarly, right ventricular (RV) end-diastolic indexed volumes were at least double the normal reference ranges in most patients (median 240: 165-268 mL/m2) on CMRI. The median normal RV systolic function was 49% for males (IQ1-IQ3, 48.0-50.0%) and 49% for females (IQ1-IQ3, 47.3-49.8%). CMRI showed that 70% of males had a normal RV systolic function compared to only 45% of females (p < 0.05). Echocardiographic markers of RV function correlated poorly with CMRI RV ejection fraction, with correlation coefficients of r = -0.28, r = -0.10, and r = -0.04. Notably, 80% of our patients demonstrated left heart dilation, and 35% had impaired left ventricular (LV) ejection fraction on echocardiography, radionuclide ventriculography, and CMRI. CONCLUSION:Echocardiography and CMRI consistently revealed right heart dilation but correlated poorly for right heart function. The evaluation of LV function should not be neglected, as some patients exhibited decreased LV ejection fraction. A holistic approach incorporating multiple modalities and clinical assessment is recommended, as the pathophysiology of PH may differ in patients with left-to-right shunts.

Background: Heart failure and cardiomyopathy are problematic in South Africa. Viruses are important causes of myocarditis and cardiomyopathy. This study aimed to determine the distribution of viruses in endomyocardial heart biopsy samples in patients with dilated cardiomyopathy. Methods: Endomyocardial biopsies (EMB) were analysed using histology, immunohistochemical staining, and polymerase chain reaction. The level of fibrosis, presence and type of cellular infiltration, and the prevalence of viral genomes with their replication activity were determined. Results: Viral genomes were found in 73.7% of patients, with parvovirus B19 (B19V) present in 96.4%. No Coxsackievirus was identified, and 2 patients presented with transcriptional intermediates, which indicated active B19V viral replication. Most patients (71.4%) presented with single infections, but some (28.6%) with co-infections. Three patients presented with acute myocardial inflammation and moderate / severe increased lymphocytic infiltration. Conclusions: This study found B19V predominant and present in almost all virus-positive EMB samples. Our results support the possible virus etiological shift towards B19V. These findings underscore the need to further investigate the pathophysiological role of B19V in the development and progression of DCM.

Vascular graft infection continues to be a highly morbid condition, still associated to high mortality. Aortoesophageal and aortobronchial fistulae are the most dreadful complications of graft infection. There is scanty related information in the literature and, due to the rarity of these communications, it is not possible to standardize the combined medical, interventional, and surgical therapy. This document aims at offering an updated overview of the most recent relevant contributions on the visceral fistulous communications, summarize what actions are usually taken and respond to the question posed in the title.

Patients undergoing surgery for acute infective endocarditis are among those with the highest risk. Their preoperative condition has significant impact on outcomes. There are specific issues related with the preoperative situation, intraoperative findings, and postoperative management. In this narrative review, focus is placed on the most critical aspects in the perioperative period including the management and weaning from mechanical ventilation, the management of vasoplegia, the management of the chest open, antithrombotic therapy, transfusion, coagulopathy, management of atrial fibrillation, the duration of antibiotic therapy, and pacemaker implantation.

BackgroundCardiomyopathies are an important cause of heart failure in Africa yet there are limited data on etiology and clinical phenotypes.ObjectivesThe IMHOTEP (African Cardiomyopathy and Myocarditis Registry Program) was designed to systematically collect data on individuals diagnosed with cardiomyopathy living in Africa.MethodsIn this multicenter pilot study, patients (age ≥13 years) were eligible for inclusion if they had a diagnosis of cardiomyopathy or myocarditis. Cases were grouped and analyzed according to phenotype; dilated cardiomyopathy (DCM) including myocarditis and peripartum cardiomyopathy, hypertrophic cardiomyopathy (HCM), arrhythmogenic cardiomyopathy (ACM), and restrictive cardiomyopathy (RCM).ResultsA total of 665 unrelated index cases (median age 35 [27-44] years; 51.1% female) were recruited at 3 centers in South Africa and 1 center in Mozambique. DCM (n = 478) was the most common type of cardiomyopathy, accounting for 72% of the cohort; ACM (n = 78), HCM (n = 70), and RCM (n = 39) were less frequent. While the age of onset and sex distribution of HCM and ACM were similar to European and North American populations, DCM and RCM had a younger age of onset and occurred more frequently in women and those with African ancestry. Causes of cardiomyopathy were diverse; familial (27%), nonfamilial/idiopathic (36%), and secondary (37%) etiologies were observed.ConclusionsIn the largest study of cardiomyopathy to-date on the African continent, we observe that DCM is the dominant form of cardiomyopathy in Southern Africa. The age of onset was significantly younger in African patients with notable sex and ethnic disparities in DCM.

Cardiomyopathies are an important cause of heart failure in Africa yet there are limited data on etiology and clinical phenotypes. The IMHOTEP (African Cardiomyopathy and Myocarditis Registry Program) was designed to systematically collect data on individuals diagnosed with cardiomyopathy living in Africa. In this multicenter pilot study, patients (age ≥13 years) were eligible for inclusion if they had a diagnosis of cardiomyopathy or myocarditis. Cases were grouped and analyzed according to phenotype; dilated cardiomyopathy (DCM) including myocarditis and peripartum cardiomyopathy, hypertrophic cardiomyopathy (HCM), arrhythmogenic cardiomyopathy (ACM), and restrictive cardiomyopathy (RCM). A total of 665 unrelated index cases (median age 35 [27-44] years; 51.1% female) were recruited at 3 centers in South Africa and 1 center in Mozambique. DCM (n = 478) was the most common type of cardiomyopathy, accounting for 72% of the cohort; ACM (n = 78), HCM (n = 70), and RCM (n = 39) were less frequent. While the age of onset and sex distribution of HCM and ACM were similar to European and North American populations, DCM and RCM had a younger age of onset and occurred more frequently in women and those with African ancestry. Causes of cardiomyopathy were diverse; familial (27%), nonfamilial/idiopathic (36%), and secondary (37%) etiologies were observed. In the largest study of cardiomyopathy to-date on the African continent, we observe that DCM is the dominant form of cardiomyopathy in Southern Africa. The age of onset was significantly younger in African patients with notable sex and ethnic disparities in DCM.

BACKGROUND:Deaths from non-communicable diseases have increased in sub-Saharan Africa over the years, with limited data on coronary artery disease (CAD) and the risk factors thereof. The objective of this study was to investigate modifiable and non-modifiable risk factors in central South Africa in patients with CAD. METHODS:Patients with angiographically confirmed CAD who were evaluated in the catheterisation laboratory for the first time over a two-year period (2016 - 2017) were included. Data were extracted from the patients' medical records. RESULTS:Four hundred and eighty-two patients met the inclusion criteria, presenting at a mean age of 58.4 ± 10.8 years, and were predominantly male (66%). Females were significantly older than the males (60.3 ± 9.6 vs 57.4 ± 11.1 years; p < 0.05). The mean age at presentation was comparable between ethnic groups, except Asian patients who presented at a significantly younger age compared to Caucasians (49.8 ± 10.5 vs 59.1 ± 10.8 years; p < 0.05). Hypertension (91%) was the most common risk factor, followed by smoking (67%) and obesity (41%). Black Africans demonstrated a higher incidence of hypertension when compared to Caucasians (96 vs 87%; p < 0.05). Smoking was more prevalent in Caucasians than black Africans (68 vs 55%; p < 0.05) and occurred more commonly in males than females (73 vs 55%; p < 0.05). Most patients presented with acute coronary syndrome (ACS) (72%), mainly with ST-elevation myocardial infarction (STEMI) (36%). The majority of patients presenting with ACS were in the age group 51 - 60 years. The ACS risk-factor profile was similar to that of the total study group. CONCLUSION:CAD was present in all ethnic groups, and modifiable and non-modifiable risk factors were similar to the classical risk factors described worldwide. Minor interracial differences were observed and hypertension was the most prevalent risk factor recorded in central South Africa. Most patients with CAD presented with ACS, particularly STEMI. Recognition of the risk factors associated with CAD would contribute to improved planning of healthcare systems and increased awareness of CAD.

Vascular graft/endograft infection (VGEI) is a constant in cardiovascular surgery with published rates between 1 and 5%. Every graft type and anatomical location is a potential target for infectious complications. These patients are sick patients with high frailty burden. Management of VGEI entails a multidisciplinary and multimodality approach. Here we review some aspects of the problem of VGEI including prevention, diagnosis, and surgical therapy with focus on recent developments in the field.

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.

Rheumatic heart disease [RHD] is the most prevalent cause of valvular heart disease in the world, outstripping degenerative aortic stenosis numbers fourfold. Despite this, global resources are firmly aimed at improving the management of degenerative disease. Reasons remain complex and include lack of resources, expertise, and overall access to valve interventions in developing nations, where RHD is most prevalent. Is it time to consider less invasive alternatives to conventional valve surgery? Several anatomical and pathological differences exist between degenerative and rheumatic valves, including percutaneous valve landing zones. These are poorly documented and may require dedicated solutions when considering percutaneous intervention. Percutaneous balloon mitral valvuloplasty (PBMV) is the treatment of choice for severe mitral stenosis (MS) but is reserved for patients with suitable valve anatomy without significant mitral regurgitation (MR), the commonest lesion in RHD. Valvuloplasty also rarely offers a durable solution for patients with rheumatic aortic stenosis (AS) or aortic regurgitation (AR). MR and AR pose unique challenges to successful transcatheter valve implantation as landing zone calcification, so central in docking transcatheter aortic valves in degenerative AS, is often lacking. Surgery in young RHD patients requires mechanical prostheses for durability but morbidity and mortality from both thrombotic complications and bleeding on Warfarin remains excessively high. Also, redo surgery rates are high for progression of aortic valve disease in patients with prior mitral valve replacement (MVR). Transcatheter treatments may offer a solution to anticoagulation problems and address reoperation in patients with prior MVR or failing ventricles, but would have to be tailored to the rheumatic environment. The high prevalence of MR and AR, lack of calcification and other unique anatomical challenges remain. Improvements in tissue durability, the development of novel synthetic valve leaflet materials, dedicated delivery systems and docking stations or anchoring systems to securely land the transcatheter devices, would all require attention. We review the epidemiology of RHD and discuss anatomical differences between rheumatic valves and other pathologies with a view to transcatheter solutions. The shortcomings of current RHD management, including current transcatheter treatments, will be discussed and finally we look at future developments in the field.

OBJECTIVES:Carotid intima-medial thickness (CIMT) is a non-invasive tool used to detect atherosclerosis and diagnose cardiovascular disease. This study aimed to determine whether pre-operative CIMT measurements correlated with intra- and postoperative outcomes in patients with acute coronary syndrome (ACS) undergoing coronary artery bypass graft (CABG) surgery. METHODS:This retrospective, analytical cohort included 89 patients diagnosed with ACS who received CABG surgery. Patients were divided into two cohorts: group 1: normal CIMT < 0.07 cm and group 2: abnormal CIMT ≥ 0.07 cm. B-mode ultrasound was used to measure the CIMT in all patients. Pre-, intra- and postoperative data and complications were recorded for each patient. RESULTS:The study included 77 (86.5%) males and 12 (13.5%) females. Pre-operative mean body mass index was significantly higher (p = 0.03) in group 2 than in group 1. Group 2 had a significantly increased incidence of diabetes (p = 0.008) and hypertension (p = 0.009), and increased NT-proBNP levels (p = 0.02). Intra- and postoperative outcomes between the groups were comparable, with no significant differences. CONCLUSION:The study showed no correlation between abnormal CIMT and increased adverse intra- and postoperative patient outcomes. Therefore, the results of this study show CIMT should not be considered a tool to predict adverse events in patients undergoing CABG surgery.

INTRODUCTIONSingle-ventricle physiology is a critical cardiac condition requiring early diagnosis and intervention. The objectives of this study were to report on the management and outcomes of patients diagnosed with single-ventricle physiology in central South Africa.METHODSThis study was a retrospective, observational analysis of patients presenting with single-ventricle physiology at the Universitas Academic Hospital in central South Africa between November 1997 and June 2021.RESULTSPatients were referred from the Free State (54%) and Northern Cape (29%) provinces and Lesotho. One hundred and fifty-four patients presented with single-ventricle physiology: 114 received interventions and 40 were not eligible for intervention. Patients presented for the first time at a median age of 34.5 days, with patients from nearby districts presenting within a few days of birth. However, patients from outlying areas presented much later. Eighty-seven patients received systemic-to-pulmonary artery shunting or pulmonary artery banding. Sixty-three patients proceeded to bidirectional Glenn procedures, and 30 patients (26%) had full palliation to Fontan. Twenty-one patients died after stage 1, six after the Glenn procedure and two after the Fontan procedure. Overall, 34 (29.8%) patients were lost to follow up.CONCLUSIONPatients in our study presented late and follow up of these patients was a challenge. The highest mortality rate occurs during the first stage of palliation. Outcomes from this study are comparable to other sub-Saharan studies.

IntroductionPatients from developing countries who require heart valve surgery are younger and have less access to open heart surgery than those from developed countries. Transcatheter heart valves (THVs) may be an alternative but are currently unsuitable for young patients because of their inadequate durability. We developed and tested a THV utilizing two new types of decellularized bovine pericardial leaflets in an ovine model.MethodsThe two decellularized tissues [one with a very low dose (0.05%) of monomeric glutaraldehyde (GA) fixation and detoxification (DF) and the other without glutaraldehyde (DE)] were compared to an industry standard [Glycar—fixed with the standard dose (0.625%) of glutaraldehyde]. THVs were manufactured with the three tissue types and implanted in the pulmonary position of nine juvenile sheep for 180 days. Baseline and post-explantation evaluations were performed to determine the hemodynamic performance of the valves and their dynamic strength, structure, biological interaction, and calcification.ResultsHeart failure occurred in one animal due to incompetence of its Glycar valve, and the animal was euthanized at 158 days. The gradients over the Glycar valves were higher at the explant than at the implant, but the DE and DF valves maintained normal hemodynamic performance throughout the study. The DF and DE tissues performed well during the mechanical testing of explanted leaflets. Glycar tissue developed thick pannus and calcification. Compared to Glycar, the DF tissue exhibited reduced pannus overgrowth and calcification and the DE tissue exhibited no pannus formation and calcification. All tissues were endothelialized adequately. There was a striking absence of host ingrowth in the DE tissue leaflets, yet these leaflets maintained integrity and mechanical function.ConclusionIn the juvenile sheep THV model, Glycar tissue developed significant pannus, calcification, and hemodynamic deterioration. Using a very low dose of monomeric GA to fix the decellularized bovine pericardium yielded less pannus formation, less calcification, and better hemodynamic function. We postulate that the limited pannus formation in the DF group results from GA. Bovine pericardium decellularized with our proprietary method resulted in inert tissue, which is a unique finding. These results justify further development and evaluation of the two decellularized tissue types in THVs for use in younger patients.

Glutaraldehyde (GA)-fixed bovine pericardial patches remain the cardiovascular industry standard despite reports of degradation, thickening, inflammation, calcification and lack of tissue remodelling. Decellularization provides the opportunity to attenuate some of these immune-mediated processes. This study compared the mechanical and morphological integrity of bovine pericardium that is GA-fixated (Glycar® patches) or decellularized (BPS), using a proprietary protocol, following implantation in an ovine model. The impact of the processing methods on tissue strength and morphology was assessed prior to implantation. Pericardial patches were then implanted in the descending aorta and main pulmonary artery of juvenile sheep (n = 6 per group) for 180 days, and clinically evaluated using echocardiography. At explanation, patches were evaluated for strength, calcification and biological interaction. Histology demonstrated a wave-like appearance of well-separated collagen fibers for BPS scaffolds that provided pore sizes adequate to promote fibroblast infiltration. The collagen of the Glycar® patches showed loss of collagen fiber integrity, making the collagen densely compacted, contributing to insignificant recipient cell infiltration. The clinical performance of both groups was excellent, and echocardiography confirmed the absence of aneurysm formation, calcification and degeneration. Explanted Glycar® patches demonstrated cells in abundance within the fibrous encapsulation that separated the implant from the host tissue. More importantly, the fibrous encapsulation also contributed to patch thickening of both the explanted aorta and pulmonary patches. The decellularized pericardial scaffolds demonstrated recellularization, resistance to calcification, re-endothelialization and adequate strength after 180-day implantation. The proprietary decellularization protocol produced pericardial scaffolds that could be considered as an alternative to GA-fixed pericardial patches.

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: The objective of this study was to compare a double-layer running suture re-anastomosis urethral stricture repair with early catheter removal to the conventional interrupted suture re-anastomosis after excision of a bulbar urethral stricture. Methods: A consecutive series of patients with bulbar urethral stricture were enrolled in the study. The patients were randomized into two groups according to an odd/even serial number distribution. Patients’ medical records were analyzed for demographics, stricture characteristics, and lower urinary tract obstructive symptoms. The outcomes were based on the presence/absence of obstructive voiding symptoms, and retrograde urethrography (RGU) performed on the first post-operative day in Group 1 and in both groups (Groups 1 and 2) at six weeks after surgery. Flexible urethroscopy was only performed on specific cases where RGU was unclear both pre- and post-operatively or when clinical recurrence was suspected. The minimum follow-up (FU) was 18 months. Success was defined as no need for subsequent dilatation, direct vision internal urethrotomy (DVIU), or urethroplasty. Results: A total of thirty-six patients with a mean age of 45 years (range 20 to 69 years) with bulbar urethral stricture were included in this study. Group 1 and Group 2 included 19 and 17 patients, respectively. Two patients were lost during randomization and subsequently to FU. The average stricture lengths were comparable between the two groups according to the retrograde urethrogram: 1.20 cm (range 0.6 to 2) in Group 1 and 1.27 cm (range 0.5 to 2.4) in Group 2, respectively (p = 0.631). The success rate for Group 1 was 90% after a mean follow-up of thirty-six months (range 20 to 40), which was clinically significant compared to the 71% in Group 2 after a mean FU of thirty-three months (range 19 to 40; p = 0.0218; 95% CI: 0.462–41.5766). Conclusions: Anastomotic urethroplasty (AR) performed with a double layer re-anastomosis had a cure rate comparable to the conventional anastomosis with interrupted sutures after a follow-up of eighteen months and longer. The urethral catheter can be safely removed within twenty-four hours after the excision of stricture and double-layer re-anastomosis.

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 (¼) 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.