A Large-Diameter Vascular Graft Replacing Animal-Derived Sealants With an Elastomeric Polymer.

INTRODUCTION: To assess the safety and efficacy of an experimental large-diameter vascular graft externally sealed with an elastomeric polymer when used as an interposition graft in the descending aorta of sheep. METHODS: The experimental vascular grafts as well as control gelatin sealed interposition grafts were inserted into the descending aorta of juvenile sheep. The grafts were assessed by time to hemostasis and blood loss during surgery and hematology and biochemistry panels at distinct time points. Magnetic resonance imaging (MRI) was performed at 3 and at 6 mo after surgery, after which the animals were euthanized and necropsies were carried out including macroscopic and microscopic examination of the grafts, anastomoses, and distal organs. RESULTS: All animals survived the study period. There was no perceivable difference in the surgical handling of the grafts. The median intraoperative blood loss was 27.5 mL (range 10.0-125.0 mL) in the experimental group and 50.0 mL (range 10.0-75.0 mL) in the control group. The median time to hemostasis was 5.0 min (range 2.0-16.0 min) minutes in the experimental group versus 6.0 min (range 4.0-6.0 min) in the control group. MRI showed normal flow and graft patency in both groups. Healing and perianastomotic endothelialization was similar in both groups. CONCLUSIONS: The experimental graft has a similar safety and performance profile and largely comparable necropsy results, in comparison to a commonly used prosthetic vascular graft, with the experimental grafts eliciting a nonadherent external fibrous capsule as the major difference compared to the control grafts that were incorporated into the periadventitia. Survival, hemostatic sealing, and hematologic and radiologic results were comparable between the study groups.

Patients' and health professionals' views on shared decision-making in age-related macular degeneration care: A qualitative study.

BACKGROUND: Age-related macular degeneration (AMD) is one of the principal causes of irreversible visual impairment in the older adult population. Recent evidence indicates that there are signs of undertreatment and overtreatment, underdiagnosis and insufficient information provision in AMD care. Shared decision-making (SDM) can aid information sharing between patients and health professionals and enhances high-quality care. This research aimed to gain insight into patients' and professionals' views on SDM in AMD care. METHODS: Semi-structured interviews were conducted with 20 patients with AMD and 19 health professionals in June and July 2020. Participants were recruited through hospitals, professional and patient associations and (social) networks. Sample representativeness was ensured in terms of sociodemographic and disease characteristics for patients, and profession-related characteristics for health professionals. Interviews were analysed according to a predetermined coding framework. RESULTS: Although SDM is receiving attention in AMD care, health professionals and patients experienced barriers in making shared decisions. The most common barriers reported included limitations in treatment options, time constraints, strict treatment guidelines and patients' comorbidity. Furthermore, most patients indicated that they were not (fully) informed about all aspects of AMD trajectory, such as the possibility to discontinue therapy or the long-term and invasive character of treatment. Some patients expressed the need for a more empathic and person-centred communication style from their health professional. CONCLUSION: The concerns raised by patients and health professionals suggest that there is room for improvement in delivery of SDM in AMD care. Findings from this study indicate that information provision and communication can be improved.

Validation of large animal models in mechanical valve research: a histologic comparison.

OBJECTIVES: Mechanical valves still require life-long anticoagulation. Preclinical animal testing is a crucial step in the assessment of valves; however, the chosen animal model should be carefully considered, and a well-controlled animal model of mechanical valve thrombosis has not been established yet. In this study, a histopathologic comparison was performed to evaluate the representativity of pigs and sheep as large animal models in bileaflet mechanical valve thrombosis research. METHODS: 10 pigs and 8 sheep were implanted with a bileaflet mechanical valve in pulmonary position. During follow-up, no anticoagulative therapy was administered. Pigs were sacrificed between 14 and 38 days for explantation and assessment of the valve. Sheep were sacrificed between 71 and 155 days. Thrombus samples were processed and (immuno)histochemical stainings were applied. A pathologist evaluated the samples morphologically and semiquantitatively and compared these samples to available slides from 3 human patients who underwent redo surgery for acute bileaflet mechanical valve thrombosis, caused by insufficient anticoagulation. RESULTS: All pigs showed macroscopically evident thrombi on the mechanical valve surface at sacrifice. In contrast, none of the sheep showed any sign of thrombus formation. Histology showed a high fibrin content in thrombi of both human and porcine cases (3/3 vs 8/10). Porcine thrombi showed more cellular organization (0/3 vs 6/10), more calcification (0/3 vs 9/10) and more endothelialization (0/3 vs 6/10). Inflammatory cells were present in all samples and were considered physiological. CONCLUSIONS: Contrary to sheep, pigs develop thrombi on their mechanical valves in the short-term if no anticoagulation is administered. Histologic comparison of human and porcine thrombi shows comparable findings. The pig model might serve interestingly for further research on valve thrombosis, if it shows not to be an overly aggressive model.

The influence of endurance exercise training on myocardial fibrosis and arrhythmogenesis in a coxsackievirus B3 myocarditis mouse model.

Nonischaemic myocardial fibrosis is associated with cardiac dysfunction, malignant arrhythmias and sudden cardiac death. In the absence of a specific aetiology, its finding as late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging is often attributed to preceding viral myocarditis. Athletes presenting with ventricular arrhythmias often have nonischaemic LGE. Previous studies have demonstrated an adverse effect of exercise on the course of acute viral myocarditis. In this study, we have investigated, for the first time, the impact of endurance training on longer-term outcomes such as myocardial fibrosis and arrhythmogenicity in a murine coxsackievirus B3 (CVB)-induced myocarditis model. Male C57BL/6J mice (n = 72) were randomly assigned to 8 weeks of forced treadmill running (EEX) or no exercise (SED). Myocarditis was induced 2 weeks later by a single intraperitoneal injection with CVB, versus vehicle in the controls (PBS). In a separate study, mice (n = 30) were subjected to pretraining for 13 weeks (preEEX), without continuation of exercise during myocarditis. Overall, continuation of exercise resulted in a milder clinical course of viral disease, with less weight loss and better preserved running capacity. CVB-EEX and preEEX-CVB mice tended to have a lower mortality rate. At sacrifice (i.e. 6 weeks after inoculation), the majority of virus was cleared from the heart. Histological assessment demonstrated prominent myocardial inflammatory infiltration and cardiomyocyte loss in both CVB groups. Inflammatory lesions in the CVB-EEX group contained higher numbers of pro-inflammatory cells (iNOS-reactive macrophages and CD8+ T lymphocytes) compared to these in CVB-SED. Treadmill running during myocarditis increased interstitial fibrosis [82.4% (CVB-EEX) vs. 56.3% (CVB-SED); P = 0.049]. Additionally, perivascular and/or interstitial fibrosis with extensive distribution was more likely to occur with exercise [64.7% and 64.7% (CVB-EEX) vs. 50% and 31.3% (CVB-SED); P = 0.048]. There was a numerical, but not significant, increase in the number of scars per cross-section (1.9 vs. 1.2; P = 0.195), with similar scar distribution and histological appearance in CVB-EEX and CVB-SED. In vivo electrophysiology studies did not induce sustained monomorphic ventricular tachycardia, only nonsustained (usually polymorphic) runs. Their cumulative beat count and duration paralleled the increased fibrosis between CVB-EEX and CVB-SED, but the difference was not significant (P = 0.084 for each). Interestingly, in mice that were subjected to pretraining only without continuation of exercise during myocarditis, no differences between pretrained and sedentary mice were observed at sacrifice (i.e. 6 weeks after inoculation and training cessation) with regard to myocardial inflammation, fibrosis, and ventricular arrhythmogenicity. In conclusion, endurance exercise during viral myocarditis modulates the inflammatory process with more pro-inflammatory cells and enhances perivascular and interstitial fibrosis development. The impact on ventricular arrhythmogenesis requires further exploration.

The natural history of CVB3 myocarditis in C57BL/6J mice: an extended in-depth characterization.

BACKGROUND AND AIMS: Viral infections are the leading cause of myocarditis. Besides acute cardiac complications, late-stage sequelae such as myocardial fibrosis may develop, importantly impacting the prognosis. Coxsackievirus B3 (CVB)-induced myocarditis in mice is the most commonly used translational model to study viral myocarditis and has provided the majority of our current understanding of the disease pathophysiology. Nevertheless, the late stages of disease, encompassing fibrogenesis and arrhythmogenesis, have been underappreciated in viral myocarditis research to date. The present study investigated the natural history of CVB-induced myocarditis in C57BL/6J mice, expanding the focus beyond the acute phase of disease. In addition, we studied the impact of sex and inoculation dose on the disease course. METHODS AND RESULTS: C57BL/6J mice (12 weeks old; n=154) received a single intraperitoneal injection with CVB to induce viral myocarditis, or vehicle (PBS) as control. Male mice (n=92) were injected with 5 × 105 (regular dose) (RD) or 5 × 106 (high dose) (HD) plaque-forming units of CVB, whereas female mice received the RD only. Animals were sacrificed 1, 2, 4, 8, and 11 weeks after CVB or PBS injection. Virally inoculated mice developed viral disease with a temporary decline in general condition and weight loss, which was less pronounced in female animals (P<.001). In male CVB mice, premature mortality occurred between days 8 and 23 after inoculation (RD: 21%, HD: 20%), whereas all female animals survived. Over the course of disease, cardiac inflammation progressively subsided, with faster resolution in female mice. There were no substantial group differences in the composition of the inflammatory cell infiltrates: predominance of cytotoxic T cells at day 7 and 14, and a switch from arginase1-reactive macrophages to iNOS-reactive macrophages from day 7 to 14 were the main findings. There was concomitant development and maturation of different patterns of myocardial fibrosis, with enhanced fibrogenesis in male mice. Virus was almost completely cleared from the heart by day 14. Serum biomarkers of cardiac damage and cardiac expression of remodeling genes were temporarily elevated during the acute phase of disease. Cardiac CTGF gene upregulation was less prolonged in female CVB animals. In vivo electrophysiology studies at weeks 8 and 11 demonstrated that under baseline conditions (i.e. in the absence of proarrhythmogenic drugs), ventricular arrhythmias could only be induced in CVB animals. The cumulative arrhythmia burden throughout the entire stimulation protocol was not significantly different between CVB and control groups. CONCLUSION: CVB inoculation in C57BL/6J mice represents a model of acute self-limiting viral myocarditis, with progression to different patterns of myocardial fibrosis. Sex, but not inoculation dose, seems to modulate the course of disease.

An interventional sheep model of severe aortic valve stenosis hemodynamics for the evaluation of alterations in coronary physiology and microvascular function.

We aimed to develop a large animal model of subcoronary aortic stenosis (AS) to study intracoronary and microcirculatory hemodynamics. A total of three surgical techniques inducing AS were evaluated in 12 sheep. Suturing the leaflets together around a dilator (n = 2) did not result in severe AS. Suturing of a pericardial patch with a variable opening just below the aortic valve (n = 5) created an AS which was poorly tolerated if the aortic valve area (AVA) was too small (0.38-1.02 cm2), but was feasible with an AVA of 1.2 cm2. However, standardization of aortic regurgitation (AR) with this technique is difficult. Therefore, we opted for implantation of an undersized AV-bioprosthesis with narrowing sutures on the leaflets (n = 5). Overall, five sheep survived the immediate postoperative period of which three had severe AS (one patch and two bioprostheses). The surviving sheep with severe AS developed left ventricular hypertrophy and signs of increased filling-pressures. Intracoronary assessment of physiological indices in these AS sheep pointed toward the development of functional microvascular dysfunction, with a significant increase in coronary resting flow and hyperemic coronary resistance, resulting in a significantly higher index of microvascular resistance (IMR) and lower myocardial resistance reserve (MRR). Microscopic analysis showed myocardial hypertrophy and signs of fibrosis without evidence of capillary rarefaction. In a large animal model of AS, microvascular changes are characterized by increased resting coronary flow and hyperemic coronary resistance resulting in increased IMR and decreased MRR. These physiological changes can influence the interpretation of regularly used coronary indices.NEW & NOTEWORTHY In an animal model of aortic valve stenosis (AS), coronary physiological changes are characterized by increased resting coronary flow and hyperemic coronary resistance. These changes can impact coronary indices frequently used to assess concomitant coronary artery disease (CAD). At this point, the best way to assess and treat CAD in AS remains unclear. Our data suggest that fractional flow reserve may underestimate CAD, and nonhyperemic pressure ratios may overestimate CAD severity before aortic valve replacement.

B-cell lymphoblastic lymphoma following intravenous BNT162b2 mRNA booster in a BALB/c mouse: A case report.

Unprecedented immunization campaigns have been rolled out worldwide in an attempt to contain the ongoing COVID-19 pandemic. Multiple vaccines were brought to the market, among two utilizing novel messenger ribonucleic acid technology. Despite their undisputed success in decreasing COVID-19-associated hospitalizations and mortality, various adverse events have been reported. The emergence of malignant lymphoma is one of such rare adverse events that has raised concern, although an understanding of the mechanisms potentially involved remains lacking. Herein, we present the first case of B-cell lymphoblastic lymphoma following intravenous high-dose mRNA COVID-19 vaccination (BNT162b2) in a BALB/c mouse. Two days following booster vaccination (i.e., 16 days after prime), at only 14 weeks of age, our animal suffered spontaneous death with marked organomegaly and diffuse malignant infiltration of multiple extranodal organs (heart, lung, liver, kidney, spleen) by lymphoid neoplasm. Immunohistochemical examination revealed organ sections positive for CD19, terminal deoxynucleotidyl transferase, and c-MYC, compatible with a B-cell lymphoblastic lymphoma immunophenotype. Our murine case adds to previous clinical reports on malignant lymphoma development following novel mRNA COVID-19 vaccination, although a demonstration of direct causality remains difficult. Extra vigilance is required, with conscientious reporting of similar cases and a further investigation of the mechanisms of action explaining the aforementioned association.

In vivo performance of a tri-leaflet mechanical heart valve prosthesis in an ovine model.

OBJECTIVES: We present the long-term results of a trileaflet (Triflo) versus bileaflet (On-X) mechanical valve in both aortic and pulmonary positions in a sheep model. METHODS: The Triflo valve was implanted in 21 female sheep in aortic (n = 8) and pulmonary position (n = 13). The On-X valve was implanted in 7 female sheep in aortic (n = 1) and pulmonary (n = 6) positions. No antithrombotic medication of any kind was given postoperatively. In the aortic group, survival cohorts were 3 and 5 months. In the pulmonary group, survival cohorts were 10 and 20 weeks. Valve performance was assessed using haematology, echocardiography and acoustic measurements combined with post-mortem pathology analysis of the downstream organs. RESULTS: The mean gradients were lower for the Triflo valve in both pulmonary [4.30 mmHg (3.70-5.73) vs 6.80 mmHg (4.63-7.96), P = 0.012] and aortic [5.1 mmHg (4.2-7.7) vs 10.7 mmHg (8.7-12.9), P = 0.007] positions. Peak gradients were lower for the Triflo valve in both pulmonary [8.05 mmHg (6.75-10.23) vs 13.15 mmHg (9.20-14.76), P = 0.005] and aortic [8.7 mmHg (7.5-12.5) vs 16.5 mmHg (14.2-19.6), P = 0.009] positions. In both positions, leaflets and housing surface were free from any deposits macro- and microscopically and comparable to nonimplanted control valves. Peripheral organs showed no signs of thrombo-embolic damage. Biochemical and haematological were comparable to preoperative. The closing click sound pressure level of the Triflo was significantly lower in both aortic [108.4 sound pressure level (102.0-115.7) vs 111.7 sound pressure level (105.5-117.0), P < 0.001] and pulmonary [103.6 sound pressure level (99.1-108.9) vs 118.5 sound pressure level (116.7-120.2), P < 0.001] position. CONCLUSIONS: Preliminary in vivo results of the Triflo valve are promising in both aortic and pulmonary positions in an ovine model. Excellent haemodynamics, stable long-term function, low valve noise and no thrombo-embolic events in the absence of antithrombotic medication lay the foundation to a future clinical first-in-man trial.

Homocysteine, S-adenosylmethionine and S-adenosylhomocysteine are associated with retinal microvascular abnormalities: the Hoorn Study.

The aim of the present study was to investigate the relationship between homocysteine and homocysteine metabolism components and retinal microvascular disorders in subjects with and without Type 2 diabetes. In this population-based study of 256 participants, aged 60-85 years, we determined total plasma homocysteine, SAM (S-adenosylmethionine) and SAH (S-adenosylhomocysteine) in plasma and erythrocytes, total folate in serum and erythrocytes, 5-MTHF (5-methyltetrahydrofolate), and vitamins B12 and B6. Participants were examined ophthalmologically by means of indirect funduscopy and two-field 45 degrees fundus photography, and were graded for retinopathy and retinal sclerotic vessel abnormalities. A computer-assisted method was used to measure retinal vessel diameters. Total plasma homocysteine was inversely associated with retinal arteriolar diameters {standardized beta, -0.20 [95% CI (confidence interval), -0.33 to -0.07]} or a decrease of 3.78 microm CRAEs (central retinal arteriolar equivalents) per 1 S.D. increase in homocysteine level (=4.6 micromol/l). In addition, the SAM/SAH ratio in plasma was inversely associated with retinal sclerotic vessel abnormalities and retinopathy [odds ratios, 0.61 (95% CI, 0.39-0.96) and 0.50 (95% CI, 0.30-0.83) per 1 S.D. respectively]. The associations were independent of age, sex, glucose tolerance status, other homocysteine metabolism components and cardiovascular risk factors. In conclusion, the results of the present study support the concept that total plasma homocysteine and a low SAM/SAH ratio in plasma, which may reflect reduced transmethylation reactions, may contribute to the pathogenesis of (retinal) microangiopathy.

Validation of automated screening for referable diabetic retinopathy with the IDx-DR device in the Hoorn Diabetes Care System.

PURPOSE: To increase the efficiency of retinal image grading, algorithms for automated grading have been developed, such as the IDx-DR 2.0 device. We aimed to determine the ability of this device, incorporated in clinical work flow, to detect retinopathy in persons with type 2 diabetes. METHODS: Retinal images of persons treated by the Hoorn Diabetes Care System (DCS) were graded by the IDx-DR device and independently by three retinal specialists using the International Clinical Diabetic Retinopathy severity scale (ICDR) and EURODIAB criteria. Agreement between specialists was calculated. Results of the IDx-DR device and experts were compared using sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV), distinguishing between referable diabetic retinopathy (RDR) and vision-threatening retinopathy (VTDR). Area under the receiver operating characteristic curve (AUC) was calculated. RESULTS: Of the included 1415 persons, 898 (63.5%) had images of sufficient quality according to the experts and the IDx-DR device. Referable diabetic retinopathy (RDR) was diagnosed in 22 persons (2.4%) using EURODIAB and 73 persons (8.1%) using ICDR classification. Specific intergrader agreement ranged from 40% to 61%. Sensitivity, specificity, PPV and NPV of IDx-DR to detect RDR were 91% (95% CI: 0.69-0.98), 84% (95% CI: 0.81-0.86), 12% (95% CI: 0.08-0.18) and 100% (95% CI: 0.99-1.00; EURODIAB) and 68% (95% CI: 0.56-0.79), 86% (95% CI: 0.84-0.88), 30% (95% CI: 0.24-0.38) and 97% (95% CI: 0.95-0.98; ICDR). The AUC was 0.94 (95% CI: 0.88-1.00; EURODIAB) and 0.87 (95% CI: 0.83-0.92; ICDR). For detection of VTDR, sensitivity was lower and specificity was higher compared to RDR. AUC's were comparable. CONCLUSION: Automated grading using the IDx-DR device for RDR detection is a valid method and can be used in primary care, decreasing the demand on ophthalmologists.

Diabetic retinopathy is associated with mortality and cardiovascular disease incidence: the EURODIAB prospective complications study.

OBJECTIVE: To study the relationship of nonproliferative and proliferative retinopathy with all-cause mortality and cardiovascular disease (CVD) incidence in type 1 diabetic patients and, additionally, the role of cardiovascular risk factors in these associations. RESEARCH DESIGN AND METHODS: This prospective study included 2,237 type 1 diabetic patients from 31 centers in 16 European countries at baseline, aged 15-60 years, who were examined for retinopathy by taking two-field 45 degrees fundus photographs, which were centrally graded. Mortality and cardiovascular morbidity follow-up was assessed 6-8 years after baseline examination according to a standardized protocol. RESULTS: After 7.9 years of follow-up, 64 patients had died and 128 patients had incident CVD. The age- and sex-adjusted hazard ratios (HRs) of all-cause mortality were 1.45 (95% CI 0.71-2.96) and 4.16 (1.96-8.84) in patients with nonproliferative and proliferative retinopathy at baseline, respectively. Adjustments for cardiovascular risk factors completely obliterated the association with nonproliferative retinopathy, whereas the association with proliferative retinopathy remained twofold increased, although nonsignificant. The age- and sex-adjusted HRs of incident CVD were 1.73 (1.15-2.60) and 2.05 (1.22-3.45) in patients with nonproliferative and proliferative retinopathy, respectively. After adjustments for cardiovascular risk factors, both associations were attenuated and lost statistical significance. CONCLUSIONS: This study shows that type 1 diabetic patients with nonproliferative or proliferative retinopathy have an increased risk for all-cause mortality and incident CVD. The presence of cardiovascular risk factors explained the associations to a large extent, except for the associations with proliferative retinopathy, which suggests that other shared mechanisms may be involved.

Are retinal microvascular abnormalities associated with large artery endothelial dysfunction and intima-media thickness? The Hoorn Study.

It has been hypothesized that microvascular dysfunction affects endothelial dysfunction of the large arteries, which may explain the relationship of microvascular disease with macrovascular disease. The aim of the present study was to investigate the relationship of retinal microvascular disorders with endothelium-dependent FMD (flow-mediated vasodilatation) and carotid IMT (intima-media thickness). A total of 256 participants, aged 60-85 years, 70 with normal glucose metabolism, 69 with impaired glucose metabolism and 109 with Type II diabetes, were included in this study. All participants were ophthalmologically examined, including funduscopy and two field 45 degrees fundus photography, and were graded for retinal sclerotic vessel abnormalities and retinopathy. Retinal arteriolar and venular diameters were measured with a computer-assisted method. Brachial artery, endothelium-dependent FMD and carotid IMT were assessed ultrasonically as measurements of endothelial function and early atherosclerosis respectively. After adjustment for age, sex and glucose tolerance status, retinal vessel diameters, retinal sclerotic vessel abnormalities and retinopathy were not significantly associated with FMD. In contrast with other retinal microvascular abnormalities, retinal venular dilatation was associated with increased IMT [standardized beta value (95% confidence interval), 0.14 (0.005-0.25)]. This association was attenuated and lost statistical significance after adjustment for cardiovascular risk factors, in particular after correction for fasting insulin. In the present study, retinal microvascular disorders are not independently associated with impaired FMD. In addition, retinal venular dilatation is associated with increased IMT, although non-significantly after multivariable adjustment for cardiovascular risk factors. Therefore our data provide evidence that retinal microvascular disease is of limited value in risk stratification for future cardiovascular events.