How to counteract the lack of donor tissue in cardiac surgery? Initial experiences with a newly established homograft procurement program

Homograft heart valves may have significant advantages and are preferred for the repair of congenital valve malformations, especially in young women of childbearing age, athletes and in patients with active endocarditis. A growing problem, however, is the mismatch between tissue donation and the increasing demand. The aim of this paper is to describe the initiation process of a homograft procurement program to attenuate the shortage of organs. A comprehensive description of the infrastructure and procedural steps required to initiate a cardiac and vascular tissue donation program combined with a prospective follow-up of all homografts explanted at our institution. Between January 2020 and May 2022, 28 hearts and 12 pulmonary bifurcations were harvested at our institution and delivered to the European homograft bank. Twenty-seven valves (19 pulmonary valves, 8 aortic valves) were processed and allocated for implantation. The reasons for discarding a graft were either contamination (n = 14), or morphology (n = 13) or leaflet damage (n = 2). Five homografts (3 PV, 2 AV) have been cryopreserved and stored while awaiting allocation. One pulmonary homograft with a leaflet cut was retrieved by bicuspidization technique and awaits allocation, as a highly requested small diameter graft. The implementation of a tissue donation program in cooperation with a homograft bank can be achieved with reasonable additional efforts at a transplant center with an in-house cardiac surgery department. Challenging situations with a potential risk of tissue injury during procurement include re-operation, harvesting by a non-specialist surgeon and prior central cannulation for mechanical circulatory support

Matched comparison of decellularized homografts and bovine jugular vein conduits for pulmonary valve replacement in congenital heart disease

For decades, bovine jugular vein conduits (BJV) and classic cryopreserved homografts have been the two most widely used options for pulmonary valve replacement (PVR) in congenital heart disease. More recently, decellularized pulmonary homografts (DPH) have provided an alternative avenue for PVR. Matched comparison of patients who received DPH for PVR with patients who received bovine jugular vein conduits (BJV) considering patient age group, type of heart defect, and previous procedures. 319 DPH patients were matched to 319 BJV patients; the mean age of BJV patients was 15.3 (SD 9.5) years versus 19.1 (12.4) years in DPH patients (p = 0.001). The mean conduit diameter was 24.5 (3.5) mm for DPH and 20.3 (2.5) mm for BJV (p < 0.001). There was no difference in survival rates between the two groups after 10 years (97.0 vs. 98.1%, p = 0.45). The rate of freedom from endocarditis was significantly lower for BJV patients (87.1 vs. 96.5%, p = 0.006). Freedom from explantation was significantly lower for BJV at 10 years (81.7 vs. 95.5%, p = 0.001) as well as freedom from any significant degeneration at 10 years (39.6 vs. 65.4%, p < 0.001). 140 Patients, matched for age, heart defect type, prior procedures, and conduit sizes of 20–22 mm (± 2 mm), were compared separately; mean age BJV 8.7 (4.9) and DPH 9.5 (7.3) years (p = n.s.). DPH showed 20% higher freedom from explantation and degeneration in this subgroup (p = 0.232). Decellularized pulmonary homografts exhibit superior 10-year results to bovine jugular vein conduits in PVR

Durability of homografts used to treat complex aortic valve endocarditis

Acute bacterial endocarditis may be extremely destructive for cardiac valves and their periannular structures. It has been suggested that complex reconstruction procedures require the use of homografts because of their versatility and potency to resist repeated infection.status: publishe

<i>Staphylococcus</i> aureus adheres avidly to decellularised cardiac homograft tissue in vitro in the fibrinogen-dependent manner

Objective: Infective endocarditis remains a severe complication associated with a high morbidity and mortality in patients after heart valve replacement. Exploration of the pathogenesis is of high demand and we, therefore, present a competent model that allows studying bacterial adherence and the role of plasma fibrinogen in this process using a new in-house designed low-volume flow chamber. Three cardiac graft tissues used for pulmonary valve replacement have been tested under shear conditions to investigate the impact of surface composition on the adhesion events. Methods: Tissue pieces of cryopreserved homograft (non-decellularised), decellularised homograft and bovine pericardium patch were investigated for fibrinogen binding. Adherence of Staphylococcus aureus to these graft tissues was studied quantitatively under flow conditions in our newly fabricated chamber based on a parallel plates' modality. The method of counting colony-forming units was reliable and reproducible to assess the propensity of different graft materials for bacterial attachment under shear. Results: Bacterial perfusions over all plasma-precoated tissues identified cryopreserved homograft with the lowest affinity for S. aureus compared to decellularised homograft presenting a significantly higher bacterial adhesion (p < 0.05), which was linked to a more avid fibrinogen binding (p < 0.01). Bovine pericardial patch, as a reference tissue in this study, was confirmed to be the most susceptible tissue graft for the bacterial adhesion, which was in line with our previous work. Conclusion: The two studied homograft tissues showed different levels of bacterial attachment, which might be postulated by the involvement of fibrinogen in the adhesion mechanism(s) shown previously for bovine tissues

Mitral valve replacement using a mitral homograft

Mitral valve dysfunction is not always amenable to repair, and may necessitate valve replacement. An alternative to standard mechanical and biological prostheses, is the use of homografts. The following manuscript and videos describe our surgical approach to mitral valve replacement with a complete mitral homograft in a cadaveric heart model

Socio-cultural context and feelings of hatred and revenge in war veterans with post-traumatic stress disorder 15 years after war in Kosovo

We aimed to assess, in socio-cultural context, the level of hatred and revenge in war veterans with post-traumatic stress disorder (PTSD). The sampling frame consisted of 215 Kosova War veterans, randomly selected. The Harvard Trauma Questionnaire was used to assess the prevalence of PTSD and Manchester Short Assessment of Life was used to assess social satisfactions. The participants were asked to declare the strength of feelings of hatred and revenge in the four preceding weeks by using four items scale: not at all, a little bit/sometimes, a lot and extremely. Willingness for action of veterans was assessed using three item scale: yes, no or maybe. A probability level of 0.05 was adopted to be considered as statistically significant for differences among groups. DSM-IV-TR criteria for PTSD (very similar to DSM-V) were met by 52.6% of veterans; the data have confirmed existence of thoughts and fantasies of revenge against opposing forces by 42.8% veterans; at the same level 42.8% manifested feelings of hatred. Fantasies of taking revenge<em> a lot</em> was recorded by 19.5% and <em>extremely</em> by 1.4% of veterans, while hateful thoughts at level a lot were likely expressed by 22.3% and <em>extreme</em> by 2.8% of veterans. It is important to note that 84.7% were confident to act based on their beliefs. Social-economic and cultural factors have played major role in the understanding of psychological problems of traumatized individuals with a direct impact on their ability to function socially. This study has confirmed the urgent need for the establishment of psychological rehabilitation programs as well as programs for the social and economic rehabilitation of War Veterans

An in vitro model to study endothelialization of cardiac graft tissues under flow

Pulmonary valve replacement is performed with excellent resultant hemodynamics in patients that have underlying congenital or acquired heart valve defects. Despite recent advancements in right ventricular outflow tract reconstruction, an increased risk of developing infective endocarditis remains, which has a more common occurrence for conduits of bovine jugular vein (BJV) origin compared with cryopreserved homografts. The reason for this is unclear although it is hypothesized to be associated with an aberrant phenotypic state of cells that reendothelialize the graft tissue postimplantation. The aim of this study was to develop an in vitro model that enables the analysis of endothelial cell (EC) attachment to cardiac graft tissues under flow. In the experiments, EC attachment was optimized on bovine pericardium (BP) patch using human umbilical vein ECs. Different biological coatings, namely gelatin, fibronectin, plasma, or a combination of fibronectin and plasma were tested. After cell adaptation, graft tissues were exposed to laminar flow in a parallel-plate flow chamber. Cell retention to the tissue was analyzed after nuclear staining with YO-PRO-1 and a membranous localization of VE-cadherin. Experiments showed that combined coating with fibronectin and blood plasma together with a two-phased shear pattern resulted in a relevant cell monolayer on BP patch and cryopreserved homograft. For BJV tissue, no adherent cells under both static and shear conditions were initially observed. In conclusion, having established the new flow chamber system we could obtain EC layers on the surface of BP patch and cryopreserved pulmonary homograft tissues. The presented in vitro system can serve as a competent model to study cell phenotypes on cardiac grafts in the close-to-physiologic environment. Moreover, this approach allows broad applications and enables further development by testing more complex conditions

The risk of transmission of the novel coronavirus (SARS-CoV-2) with human heart valve transplantation: evaluation of cardio-vascular tissues from two consecutive heart donors with asymptomatic COVID-19.

We report on two living donors of explanted hearts while receiving heart transplantation that tested positive for SARS-CoV-2 on the day of donation, although clinically asymptomatic. They underwent heart transplantation for ischaemic and hypertrophic obstructive cardiomyopathy, respectively. After evaluation of donor hearts, we cryopreserved and stored two pulmonary valves for clinical application and one aortic valve for research. Light microscopy of myocardium, mitral valve and aortic and pulmonary arterial wall and RT-PCR SARS-CoV-2 test of myocardium, mitral and tricuspid valve and aortic wall for detection of SARS-CoV-2 were performed. Presence of ACE2 in tissues was assessed with immunostaining. Light microscopy revealed a mild eosinophilic myocarditis in the ischemic cardiomyopathy heart, whereas enlarged cardiomyocytes with irregular nucleus and some with cytoplasmic vacuoles in the hypertrophic obstructive cardiomyopathy heart. Aortic and pulmonary wall were histologically normal. Immunostaining revealed diffuse presence of ACE2 in the myocardium of the heart with eosinophilic myocarditis, but only discrete presence in the hypertrophic cardiomyopathy heart. The RT-PCR SARS-CoV-2 test showed no presence of the virus in tested tissues. Despite eosinophilic myocarditis in the ischemic cardiomyopathy heart, no viral traces were found in the myocardium and valve tissues. However, ACE2 was present diffusely in the ischemic cardiomyopathy heart. SARS-CoV-2 could not be detected in the cardiac tissues of these COVID-19 asymptomatic heart donors. In our opinion, clinical application of the valves from these donors presents negligible risk for coronavirus transmission. Nonetheless, considering the uncertainty regarding the risk of virus transmission with the human tissue transplantation, we would not release in any case the pulmonary valve recovered from the eosinophilic myocarditis heart. In contrast, we may consider the release of the pulmonary valve from the dilated cardiomyopathy heart only for a life-threatening situation when no other similar allograft were available