Four-Year Outcomes of Left Main Percutaneous Coronary Intervention with a Bioresorbable Scaffold in the Circumflex Ostium.

Objectives: The study aimed to investigate the long-term outcomes of a double stent scaffold strategy in patients with left main (LM) bifurcation lesions involving the ostium of the left circumflex artery (LCX), utilizing a drug-eluting stent (DES) in the LM extending into the left anterior descending artery (LAD) and a bioresorbable vascular scaffold (BVS) in the LCX ostium. Background: The high occurrence of in-stent restenosis of the LCX ostium is the major limitation of percutaneous coronary intervention (PCI) for LM lesions with a two-stent strategy. Methods: This was a single-center, prospective, single-arm study of 46 consecutively enrolled patients with a stable coronary artery disease and significant unprotected LM distal bifurcation disease. Patients underwent imaging-guided PCI using DES in the LM-LAD and BVS in the LCX using a T-stent or mini-crush technique. The primary outcome at four years was the composite of death, myocardial infarction, stroke, and target lesion revascularization (TLR). Results: At four years, the primary outcome was identified in 9 patients (19.6%). All events were TLRs except one myocardial infarction due to BVS thrombosis. Seven of the eight TLRs were a result of side branch BVS restenosis. Univariate predictors of the 4-year outcome were higher LDL cholesterol and BVS size ≤2.5 mm. On multivariate analysis, LCX lesion preparation with a cutting balloon and post-procedure use of intravascular ultrasound for optimization were found to be independent protective factors of MACE. Conclusions: In selected patients with LM distal bifurcation disease, an imaging-guided double stent scaffold strategy with DES in the LM and BVS in the LCX ostium was technically successful in all patients and was reasonably safe and effective for four years.

Lead-Related Infective Endocarditis in Latvia: A Single Centre Experience.

Background and Objectives: Over the last five decades cardiac implantable electronic devices (CIED) have become established as the mainstay for the treatment of permanent bradycardias, chronic heart failure and dangerous heart rhythm disturbances. These devices improve survival and quality of life in many patients. However, infections associated with CIED implantation, particularly lead-related infective endocarditis (LRIE), can offset all benefits and make more harm than good for the patient. To date, there are no other studies in Latvia, addressing patients with lead-related infective endocarditis. The objective of this study was to identify the most common pathogens associated with LRIE and their antimicrobial resistance and to identify possible risk factors of patients who present with LRIE. Materials and Methods: The study was performed retrospectively at Pauls Stradins Clinical University Hospital (PSCUH). The study included patients who were referred to PSCUH due to LRIE for lead extraction. Patients were identified from procedural journals. Information about isolated microorganisms, patient comorbidities and visual diagnostics data was taken from patient records. Results: Forty-nine patients with CIED related infective endocarditis were included in the study, 34 (69.4%) were male, median age of all patients was 65.0 (50.5-73.0) years, median hospital stay was 15.5 (22.0-30.5) days. Successful and complete lead extraction was achieved in all patients. Thirty-two (65.3%) had received antibiotics prior to blood sample. Only in 31 (63.3%) positive culture results were seen. The most common isolated pathogens were Staphylococcus aureus (23.5%) and coagulase negative staphylococci (23.5%). Other bacteria were isolated considerably less often. The atrial lead was most common location for lead vegetations, seen in 50.0% of cases. Five (10.2%) patients have died due to the disease. Conclusions: Lead-related infective endocarditis is a major complication of cardiac implantable electronic devices with considerable morbidity and mortality, which in our study was as high as 10.2%.

Age-related analysis of structural, biochemical and mechanical properties of the porcine mitral heart valve leaflets.

The aim of this study was to assess structural and biochemical differences in the extracellular matrix of the fetal and adult porcine mitral heart valves in relation to their mechanical characteristics. Using tensile tests it was demonstrated that the material properties of porcine mitral heart valves progressively change with age. The collagen content of the adult heart valve, as estimated by hydroxyproline assay, increases three times as compared with fetal heart valves. Transmission electron microscopy demonstrated that the diameter of collagen fibrils increased in adult heart valves compared with fetal heart valves. The level of collagen cross-linking is lower in the fetal heart valve than the adult heart valve. The reported age differences in the material properties of fetal and adult porcine heart valves were associated with increases in collagen content, the diameter of collagen fibrils and the level of collagen cross-linking. These data lay a foundation for systematic elucidation of the structural determinants of material properties of heart valves during embryonic and postnatal valvulogenesis. They are also essential to define the desirable level of tissue maturation in heart valve tissue engineering.

Risk factors associated with mortality in the infective endocarditis patients requiring cardiac surgery: a study based on Latvian population.

BACKGROUND: Increased life expectancy, developments in medicine and intracardiac devices, accessibility of cardiac surgery, decrease in the prevalence of rheumatic heart disease are changing infective endocarditis patient profile and thus risk factors for the adverse events. This single-center-based study covering the whole Latvian population aimed to assess the intrahospital and 3-year mortality of infective endocarditis patients who underwent cardiac surgery, as well as risk factors and laboratory indices predictive of adverse outcomes of the disease. METHODS: Clinical profiles, data of laboratory and instrumental analyses, operation and intensive care unit records of cardiac surgery patients treated in Pauls Stradins Clinical University Hospital, Riga, Latvia, between 2015 and 2019 were analyzed. RESULTS: We analyzed data from 242 episodes of surgically treated infective endocarditis in 233 patients. The median age of patients was 57.00 (45.00-68.00) years. The rate of intrahospital mortality was 11.16%. Risk factors associated with mortality in the univariate analyses were S. aureus infection (HR=2.27, 95% CI: 1.36-3.80; P=0.002) and systemic embolization of vegetations (HR=1.63, 95% CI: 1.00-2.64; P=0.048). Perivalvular complications (HR=1.98, 95% CI: 1.19-3.29; P=0.009) were found to be independently associated with mortality in multivariate analysis (HR=1.99, 95% CI: 1.05-3.78; P=0.035). One-year survival was 78.3%, whereas three-year -71.3%. CONCLUSIONS: Intrahospital mortality of surgically treated IE patients was 11.2%; however, one- and three-year mortality was 21.7 and 28.7%, respectively. Perivalvular complications were independently associated with mortality. Laboratory indices were not predictive of adverse outcomes.

Comparison of outcome between blood culture positive and negative infective endocarditis patients undergoing cardiac surgery.

BACKGROUND: Up to 30% or even more of all infective endocarditis (IE) cases are recognized as blood culture negative, meaning that the causative agent is left unidentified. The prompt diagnosis together with the identification of causative microorganism and targeted antibiotic treatment can significantly impact the prognosis of the disease and further patient's health status. In some studies, blood culture negative endocarditis has been shown to be associated with delayed diagnosis, worse outcome and course of the disease, and a greater number of intra and postoperative complications. METHODS: We retrospectively analysed the medical records of all patients who underwent cardiac surgery for endocarditis between years 2016 and 2019. The aim of this study was to analyse short and long-term mortality and differences of laboratory, clinical and echocardiography parameters in patients with blood culture positive endocarditis (BCPE) and blood culture negative endocarditis (BCNE) and its possible impact on the clinical outcome. RESULTS: In our study population were 114 (55.1%) blood culture positive and 93 (44.9%) blood culture negative cases of infectious endocarditis. The most common pathogens in the blood culture positive IE group were S.aureus in 36 cases (31.6%), Streptococcus spp. in 27 (23.7%), E.faecalis in 24 (21.1%), and other microorganisms in 27 (23.7%). Embolic events were seen in 60 patients (28.9%). In univariate analyses, detection of microorganism, elevated levels of procalcitonin were found to be significantly associated with intrahospital death, however it did not reach statistical significance in multivariate analyses. Among microorganisms, S.aureus was significantly associated with intrahospital death in both univariate and multivariate analyses. CONCLUSIONS: There are no statistically significant differences between groups of BCPE and BCNE in terms of intrahospital mortality, hospital and ICU stay or 3-year mortality. There were higher levels of procalcitonin in BCPE group, however procalcitonin failed to show independent association with mortality in multivariate analysis. The most common microorganism in the BCPE group was S.aureus. It was associated with independently higher intrahospital mortality when compared to other causative microorganisms.

The Cancer Aneuploidy Paradox: In the Light of Evolution.

Aneuploidy should compromise cellular proliferation but paradoxically favours tumour progression and poor prognosis. Here, we consider this paradox in terms of our most recent observations of chemo/radio-resistant cells undergoing reversible polyploidy. The latter perform the segregation of two parental groups of end-to-end linked dyads by pseudo-mitosis creating tetraploid cells through a dysfunctional spindle. This is followed by autokaryogamy and a homologous pairing preceding a bi-looped endo-prophase. The associated RAD51 and DMC1/γ-H2AX double-strand break repair foci are tandemly situated on the AURKB/REC8/kinetochore doublets along replicated chromosome loops, indicative of recombination events. MOS-associated REC8-positive peri-nucleolar centromere cluster organises a monopolar spindle. The process is completed by reduction divisions (bi-polar or by radial cytotomy including pedogamic exchanges) and by the release of secondary cells and/or the formation of an embryoid. Together this process preserves genomic integrity and chromosome pairing, while tolerating aneuploidy by by-passing the mitotic spindle checkpoint. Concurrently, it reduces the chromosome number and facilitates recombination that decreases the mutation load of aneuploidy and lethality in the chemo-resistant tumour cells. This cancer life-cycle has parallels both within the cycling polyploidy of the asexual life cycles of ancient unicellular protists and cleavage embryos of early multicellulars, supporting the atavistic theory of cancer.

Upregulation of meiosis-specific genes in lymphoma cell lines following genotoxic insult and induction of mitotic catastrophe.

BACKGROUND: We have previously reported that p53 mutated radioresistant lymphoma cell lines undergo mitotic catastrophe after irradiation, resulting in metaphase arrest and the generation of endopolyploid cells. A proportion of these endopolyploid cells then undergo a process of de-polyploidisation, stages of which are partially reminiscent of meiotic prophase. Furthermore, expression of meiosis-specific proteins of the cancer/testis antigens group of genes has previously been reported in tumours. We therefore investigated whether expression of meiosis-specific genes was associated with the polyploidy response in our tumour model. METHODS: Three lymphoma cell lines, Namalwa, WI-L2-NS and TK6, of varying p53 status were exposed to a single 10 Gy dose of gamma radiation and their responses assessed over an extended time course. DNA flow cytometry and mitotic counts were used to assess the kinetics and extent of polyploidisation and mitotic progression. Expression of meiotic genes was analysed using RT-PCR and western blotting. In addition, localisation of the meiotic cohesin REC8 and its relation to centromeres was analysed by immunofluorescence. RESULTS: The principal meiotic regulator MOS was found to be significantly post-transcriptionally up-regulated after irradiation in p53 mutated but not p53 wild-type lymphoma cells. The maximum expression of MOS coincided with the maximal fraction of metaphase arrested cells and was directly proportional to both the extent of the arrest and the number of endopolyploid cells that subsequently emerged. The meiotic cohesin REC8 was also found to be up-regulated after irradiation, linking sister chromatid centromeres in the metaphase-arrested and subsequent giant cells. Finally, RT-PCR revealed expression of the meiosis-prophase genes, DMC1, STAG3, SYCP3 and SYCP1. CONCLUSION: We conclude that multiple meiotic genes are aberrantly activated during mitotic catastrophe in p53 mutated lymphoma cells after irradiation. Furthermore, we suggest that the coordinated expression of MOS and REC8 regulate the extent of arrested mitoses and polyploidy.

Cancer/testis antigens and gametogenesis: a review and "brain-storming" session.

Genes expressed both in normal testis and in malignancies (Cancer/ Testis associated genes - CTA) have become the most extensively studied antigen group in the field of tumour immunology. Despite this, many fundamentally important questions remain unanswered: what is the connection between germ-cell specific genes and tumours? Is the expression of these genes yet another proof for the importance of genome destabilisation in the process of tumorigenesis?, or maybe activation of these genes is not quite random but instead related to some programme giving tumours a survival advantage?This review collates most of the recent information available about CTAs expression, function, and regulation. The data suggests a programme related to ontogenesis, mostly to gametogenesis. In the "brain-storming" part, facts in conflict with the hypothesis of random CTA gene activation are discussed. We propose a programme borrowed from organisms phylogenetically much older than humans, which existed before the differentiation of sexes. It is a programme that has served as a life cycle with prominent ploidy changes, and from which, as we know, the germ-cell ploidy cycle - meiosis - has evolved. Further work may show whether this hypothesis can lead to a novel anti-tumour strategy.

The fusion of tissue spheroids attached to pre-stretched electrospun polyurethane scaffolds.

Effective cell invasion into thick electrospun biomimetic scaffolds is an unsolved problem. One possible strategy to biofabricate tissue constructs of desirable thickness and material properties without the need for cell invasion is to use thin (<2 µm) porous electrospun meshes and self-assembling (capable of tissue fusion) tissue spheroids as building blocks. Pre-stretched electrospun meshes remained taut in cell culture and were able to support tissue spheroids with minimal deformation. We hypothesize that elastic electrospun scaffolds could be used as temporal support templates for rapid self-assembly of cell spheroids into higher order tissue structures, such as engineered vascular tissue. The aim of this study was to investigate how the attachment of tissue spheroids to pre-stretched polyurethane scaffolds may interfere with the tissue fusion process. Tissue spheroids attached, spread, and fused after being placed on pre-stretched polyurethane electrospun matrices and formed tissue constructs. Efforts to eliminate hole defects with fibrogenic tissue growth factor-ß resulted in the increased synthesis of collagen and periostin and a dramatic reduction in hole size and number. In control experiments, tissue spheroids fuse on a non-adhesive hydrogel and form continuous tissue constructs without holes. Our data demonstrate that tissue spheroids attached to thin stretched elastic electrospun scaffolds have an interrupted tissue fusion process. The resulting tissue-engineered construct phenotype is a direct outcome of the delicate balance of the competing physical forces operating during the tissue fusion process at the interface of the pre-stretched elastic scaffold and the attached tissue spheroids. We have shown that with appropriate treatments, this process can be modulated, and thus, a thin pre-stretched elastic polyurethane electrospun scaffold could serve as a supporting template for rapid biofabrication of thick tissue-engineered constructs without the need for cell invasion.

Comparison of radial deformability of stent posts of different aortic bioprostheses.

OBJECTIVES: Little is known about the stent deformability required for optimal stented heart valve bioprosthesis design. Therefore, two bioprosthetic valves with known good long-term clinical results were tested. The strain in the radial direction of the stent posts of these valves was compared with contemporary bioprosthetic valves and a native porcine aortic root. METHODS: Medtronic Intact and Carpentier-Edwards Standard (CES), and four contemporary bioprostheses, including one self-expanding prosthesis, were tested with three sonomicrometry probes per valve fixed at commissure attachment points. The mean values from 2400 data points from three measurements of the interprobe distances were used to calculate the radius of the circle circumscribed around the three probes. Changes in the radius of the aortic root at pressures 70-90 and 120-140 mmHg (pressure during diastole and systole) and that of the stent posts at 70-90 and 0-10 mmHg (transvalvular pressure gradient during diastole and systole) were compared. RESULTS: An increase in radius by 7.3 ± 2.6, 8.7 ± 0.0 and 3.9 ± 0.0% for the porcine aortic root, CES and Intact valves, respectively, was observed during transition from diastolic to systolic pressure and less for contemporary bioprostheses-mean 2.5 ± 0.9%, lowest 1.2 ± 0.0. CONCLUSIONS: The results indicate that the radial deformability of bioprosthetic valve stent posts can be as low as 1.2% for xenoaortic and 3.0% for xenopericardial prostheses with no compromise of valve durability. Although these results suggest that valve stent post-deformability might not be of critical importance, a concrete answer to the question of the significance of stent deformability for valve durability can be obtained only by acquiring long-term follow-up results for valve prostheses with rigid stents.

Rapid prototyping of compliant human aortic roots for assessment of valved stents.

Adequate in-vitro training in valved stents deployment as well as testing of the latter devices requires compliant real-size models of the human aortic root. The casting methods utilized up to now are multi-step, time consuming and complicated. We pursued a goal of building a flexible 3D model in a single-step procedure. We created a precise 3D CAD model of a human aortic root using previously published anatomical and geometrical data and printed it using a novel rapid prototyping system developed by the Fab@Home project. As a material for 3D fabrication we used common house-hold silicone and afterwards dip-coated several models with dispersion silicone one or two times. To assess the production precision we compared the size of the final product with the CAD model. Compliance of the models was measured and compared with native porcine aortic root. Total fabrication time was 3 h and 20 min. Dip-coating one or two times with dispersion silicone if applied took one or two extra days, respectively. The error in dimensions of non-coated aortic root model compared to the CAD design was <3.0% along X, Y-axes and 4.1% along Z-axis. Compliance of a non-coated model as judged by the changes of radius values in the radial direction by 16.39% is significantly different (P<0.001) from native aortic tissue--23.54% at the pressure of 80-100 mmHg. Rapid prototyping of compliant, life-size anatomical models with the Fab@Home 3D printer is feasible--it is very quick compared to previous casting methods.

Towards no-scar cardiac surgery - minimally invasive access through umbilicus for aortic valve replacement.

There is an ever-growing trend towards less-invasive procedures in all fields of medicine. We designed an animal study to prove the concept that trans-apical aortic valve replacement from an incision within the umbilicus through a single channel for instruments is feasible, which would be a major leap towards no-scar cardiac surgery. In three adult pigs, after creating a single 3-cm incision at a place where the human umbilicus would be, we introduced a 30F sheath through a tunnel created by an endoscopic vein-harvesting device up to the cardiac apex, through it and up to the left ventricle simulating the approach for trans-apical aortic valve replacement. We used a standard Amplatz nitinol occluder to seal the defect in ventricle wall later. The animals were followed up for 1h. Blood loss was minimal, and no tamponade occurred in any of the animals. In addition, we performed a test with water column static pressure to evaluate the impact of preclotting on the sealing properties of the occluders: 1 min flow-through was 2860+/-176 ml for the standard occluders and 348+/-56 ml for preclotted occluders (p<0.001).

A new training set-up for trans-apical aortic valve replacement.

Trans-apical aortic valve replacement (AVR) is a new and rapidly growing therapy. However, there are only few training opportunities. The objective of our work is to build an appropriate artificial model of the heart that can replace the use of animals for surgical training in trans-apical AVR procedures. To reduce the necessity for fluoroscopy, we pursued the goal of building a translucent model of the heart that has nature-like dimensions. A simplified 3D model of a human heart with its aortic root was created in silico using the SolidWorks Computer-Aided Design (CAD) program. This heart model was printed using a rapid prototyping system developed by the Fab@Home project and dip-coated two times with dispersion silicone. The translucency of the heart model allows the perception of the deployment area of the valved-stent without using heavy imaging support. The final model was then placed in a human manikin for surgical training on trans-apical AVR procedure. Trans-apical AVR with all the necessary steps (puncture, wiring, catheterization, ballooning etc.) can be realized repeatedly in this setting.

St Jude Epic heart valve bioprostheses versus native human and porcine aortic valves - comparison of mechanical properties.

OBJECTIVES: The major problem with heart valve bioprostheses made from chemically treated porcine aortic valves is their limited longevity caused by gradual deterioration, which has a causal link with valve tissue mechanical properties. To our best knowledge, there are no published studies on the mechanical properties of modern, commercially available bioprostheses comparing them to native human valves. The objective of this study is to determine the mechanical properties of St Jude Epic bioprostheses and to compare them with native human and porcine aortic valves. METHODS: Leaflets from eight porcine aortic valves and six Epic bioprostheses were analyzed using uni-axial tensile tests in radial and circumferential directions. Mechanical properties of human valves have been previously published by our group. Results are represented as mean values+/-S.D. RESULTS: Circumferential direction. Modulus of elasticity of Epic bioprostheses in circumferential direction at the level of stress 1.0 MPa is 101.99+/-58.24 MPa, 42.3+/-4.96 MPa for native porcine and 15.34+/-3.84 MPa for human aortic valves. Ultimate stress is highest for Epic bioprostheses 5.77+/-1.94 MPa, human valves have ultimate stress of 1.74+/-0.29 MPa and porcine 1.58+/-0.26 MPa. Ultimate strain in circumferential direction is highest for human valves 18.35+/-7.61% followed by 7.26+/-0.69% for porcine valves and 5.95+/-1.54% for Epic bioprostheses. Radial direction. Modulus of elasticity in radial direction is 9.18+/-1.81 MPa for Epic bioprostheses, 5.33+/-0.61 MPa for native porcine, and 1.98+/-0.15 MPa for human aortic valve leaflets. In the radial direction ultimate stress is highest for Epic bioprostheses 0.7+/-0.21 MPa followed by native porcine valves 0.55+/-0.11 MPa and 0.32+/-0.04 MPa for human valves. For human valves ultimate strain is 23.92+/-4.87%, for native porcine valves 8.57+/-0.8% and 7.92+/-1.74% for Epic bioprostheses. CONCLUSIONS: Epic bioprostheses have non-linear stress-strain behavior similar to native valve tissue, but they are significantly stiffer and hence less elastic compared to native porcine and human aortic valves. These differences in mechanical properties may cause variations in stress distribution within leaflets of the bioprosthetic valves and accelerate their deterioration.

Activation of meiosis-specific genes is associated with depolyploidization of human tumor cells following radiation-induced mitotic catastrophe.

Cancer is frequently characterized histologically by the appearance of large cells that are either aneuploid or polyploid. Aneuploidy and polyploidy are hallmarks of radiation-induced mitotic catastrophe (MC), a common phenomenon occurring in tumor cells with impaired p53 function following exposure to various cytotoxic and genotoxic agents. MC is characterized by altered expression of mitotic regulators, untimely and abnormal cell division, delayed DNA damage, and changes in morphology. We report here that cells undergoing radiation-induced MC are more plastic with regards to ploidy and that this plasticity allows them to reorganize their genetic material through reduction division to produce smaller cells which are morphologically indistinguishable from control cells. Experiments conducted with the large-scale digital cell analysis system are discussed and show that a small fraction of polyploid cancer cells formed via radiation-induced MC can survive and start a process of depolyploidization that yields various outcomes. Although most multipolar divisions failed and cell fusion occurred, some of these divisions were successful and originated a variety of cell progeny characterized by different ploidy. Among these ploidy phenotypes, a progeny of small mononucleated cells, indistinguishable from the untreated control cells, is often seen. We report here evidence that meiosis-specific genes are expressed in the polyploid cells during depolyploidization. Tumor cells might take advantage of the temporary change from a promitotic to a promeiotic division regimen to facilitate depolyploidization and restore the proliferative state of the tumor cell population. These events might be mechanisms by which tumor progression and resistance to treatment occur in vivo.

A new self-expanding aortic stent valve with annular fixation: in vitro haemodynamic assessment.

OBJECTIVE: Balloon-expandable stent valves require flow reduction during implantation (rapid pacing). The present study was designed to compare a self-expanding stent valve with annular fixation versus a balloon-expandable stent valve. METHODS: Implantation of a new self-expanding stent valve with annular fixation (Symetis, Lausanne, Switzerland) was assessed versus balloon-expandable stent valve, in a modified Dynatek Dalta pulse duplicator (sealed port access to the ventricle for transapical route simulation), interfaced with a computer for digital readout, carrying a 25 mm porcine aortic valve. The cardiovascular simulator was programmed to mimic an elderly woman with aortic stenosis: 120/85 mmHg aortic pressure, 60 strokes/min (66.5 ml), 35% systole (2.8 l/min). RESULTS: A total of 450 cardiac cycles was analysed. Stepwise expansion of the self-expanding stent valve with annular fixation (balloon-expandable stent valve) resulted in systolic ventricular increase from 120 to 121 mmHg (126 to 830+/-76 mmHg)*, and left ventricular outflow obstruction with mean transvalvular gradient of 11+/-1.5 mmHg (366+/-202 mmHg)*, systolic aortic pressure dropped distal to the valve from 121 to 64.5+/-2 mmHg (123 to 55+/-30 mmHg) N.S., and output collapsed to 1.9+/-0.06 l/min (0.71+/-0.37 l/min* (before complete obstruction)). No valve migration occurred in either group. (*=p<0.05). CONCLUSIONS: Implantation of this new self-expanding stent valve with annular fixation has little impact on haemodynamics and has the potential for working heart implantation in vivo. Flow reduction (rapid pacing) is not necessary.