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Background: Arteriovenous fistulas (AVF) represent a low resistant circuit. It is known that their opening leads to decreased systemic vascular resistance, increased cardiac output and other hemodynamic changes. Possible competition of AVF and perfusion of other organs has been observed before, however the specific impact of AVF has not been elucidated yet. Previous animal models studied long-term changes associated with a surgically created high flow AVF. The aim of this study was to create a simple AVF model for the analysis of acute hemodynamic changes. Methods: Domestic female pigs weighing 62.6 ± 5.2 kg were used. All the experiments were held under general anesthesia. The AVF was created using high-diameter ECMO cannulas inserted into femoral artery and vein. Continuous hemodynamic monitoring was performed throughout the protocol. Near-infrared spectroscopy sensors, flow probes and flow wires were inserted to study brain and heart perfusion. Results: AVF blood flow was 2.1 ± 0.5 L/min, which represented around 23% of cardiac output. We observed increase in cardiac output (from 7.02 ± 2.35 L/min to 9.19 ± 2.99 L/min, p = 0.0001) driven dominantly by increased heart rate, increased pulmonary artery pressure, and associated right ventricular work. Coronary artery flow velocity rose. On the contrary, carotid artery flow and brain and muscle tissue oxygenation measured by NIRS decreased significantly. Conclusions: Our new non-surgical AVF model is reproducible and demonstrated an acute decrease of brain and muscle perfusion. [ABSTRACT FROM AUTHOR]

Introduction: Data on management of severe accidental hypothermia published from an established high-volume extracorporeal membrane oxygenation centre are scarce. Methods: A total of 28 patients with intravesical temperature lower than 28°C on admission were either treated with veno-arterial extracorporeal membrane oxygenation or rewarmed conservatively. Results: A total of 10 patients rewarmed on veno-arterial extracorporeal membrane oxygenation (age: 37 ± 12.6 years) and 18 conservatively (age: 55.2 ± 11.2 years) were collected over a course of 5 years. The dominant cause was alcohol intoxication with exposure to cold (39%), 12 patients were resuscitated prior to admission. The admission temperature in the extracorporeal membrane oxygenation group (23.8 ± 2.6°C) was lower than in the non–extracorporeal membrane oxygenation group (26.0 ± 1.5°C, p = 0.01). The peripheral percutaneous veno-arterial extracorporeal membrane oxygenation was always cannulated in malignant arrhythmias causing refractory cardiac arrest. The typical extracorporeal membrane oxygenation blood flow was 3-4 L/minute and sweep gas flow 2 L/minute, the median extracorporeal membrane oxygenation duration was 48.3 (28.1-86.7) hours. The median rates of rewarming did not differ (0.41 (0.35-0.7)°C/hour in extracorporeal membrane oxygenation and 0.77 (0.54-0.98)°C/hour in non–extracorporeal membrane oxygenation, p = 0.46) as well as the admission arterial lactate, pH and potassium. Their development was not different between the groups except for higher pH between the third and ninth hour of rewarming in the extracorporeal membrane oxygenation group. The hospital mortality was 10% in the extracorporeal membrane oxygenation group and 11.1% in the non–extracorporeal membrane oxygenation group with the median last Glasgow Coma Scale 15 and Cerebral Performance Score 1. Conclusion: Veno-arterial extracorporeal membrane oxygenation for severe hypothermia shows promising outcome data collected in an extracorporeal membrane oxygenation/extracorporeal cardiopulmonary resuscitation centre located in a European urban area. Except for presence of refractory cardiac arrest, the established hypothermia-related prognostic indicators did not differ between patients in need for extracorporeal membrane oxygenation and those rewarmed without extracorporeal membrane oxygenation. [ABSTRACT FROM AUTHOR]

Aim. To assess the systemic and local immunological response to subcutaneous implants of a vascular graft covered with collagen extracted from the European carp (freshwater fish) or with collagen of bovine origin. Methods. Pieces of a vascular graft covered by pure bovine (Bos taurus, BOV, n=14) or carp (Cyprinus carpio, CYP, n=14) collagen 5 mm in size were implanted subcutaneously in the dorsum of a Balb/cOla mice. A sham operation group of 12 animals served as the control. At 7 and 14 days after the operation, one-half of each group was terminated and blood for serum, spleen, and implant with surrounding tissue were collected. Mean cytokine (TNF-α, IL-10, IL-4, IL-1β, IL-13, and IFN-γ) levels in serum were determined using ELISA. Spleen cell cultures were used for in vitro testing of lymphocyte proliferation and cytokine secretion. Local expressions of IL-6, IL-10, TNF-α, TGF-β, CCL-2, and CCL-3 were determined using PCR. Results. We found no significant difference among control, BOV, and CYP groups in mean cytokine serum levels at seven days. At day 14, the BOV group had higher levels of TNF-α (P=.018) and both the BOV and CYP groups had lower levels of IL-4 (P=.011 and P=.047, respectively) compared with the control group. Both tested implants showed only a minimal effect on the production of selected cytokines. Cell proliferation in the CYP group stimulated by CYP gel at 14 days was significantly lower than by BOV gel in BOV group (P=.0031) or by CYP gel in the control group (P=.041). The difference between the groups in the local RNA expression of all the tested mediators both at 7 and at 14 days was not significant apart from a lower level of TNF-α in the BOV group compared to CYP at 14 days (P=.013). Conclusions. Implants covered with carp collagen induce an immunological response that is comparable to that of bovine collagen covered implants in a mouse model. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to develop a prototype of an artificial blood vessel which has similar mechanical properties to a human saphenous vein graft and to experimentally verify the function of the prosthesis via ovine carotid bypass implantation. Material and methods: The prototype of an artificial graft prosthesis for low flow was developed and manufactured from a collagenous matrix and reinforcing polyester mesh. We compared the results of both the pressurisation and the mechanical stress evaluation tests of VSM with four types of hybrid vascular graft. The most similar graft (type II) was chosen for the first ovine model implantation. Results: Dominant behavior e.g. mechanical response of VSM graft in plots of circumferential and axial stress during loading is observed in circumferential direction. Average results of used VSM showed area of ideal mechanical response and the properties of artificial blood vessels were fitted into this area. Developed graft remained patent after 161 days of follow up in ovine model. Conclusions: The mechanical properties of the graft were designed and adjusted to be similar to the behaviour of human saphenous veins. This approach showed promising results and enhanced the final performance of the prosthesis. [ABSTRACT FROM AUTHOR]

Aim. The aim of this study was to evaluate short-term patency of the new prosthetic graft and its structural changes after explantation. Methods. The study team developed a three-layer conduit composed of a scaffold made from polyester coated with collagen from the inner and outer side with an internal diameter of 6 mm. The conduit was implanted as a bilateral bypass to the carotid artery in 7 sheep and stenosis was created in selected animals. After a period of 161 days, the explants were evaluated as gross and microscopic specimens. Results. The initial flow rate (median ± IQR) in grafts with and without artificial stenosis was 120±79 ml/min and 255±255 ml/min, respectively. Graft occlusion occurred after 99 days in one of 13 conduits (patency rate: 92%). Wall-adherent thrombi occurred only in sharp curvatures in two grafts. Microscopic evaluation showed good engraftment and preserved structure in seven conduits; inflammatory changes with foci of bleeding, necrosis, and disintegration in four conduits; and narrowing of the graft due to thickening of the wall with multifocal separation of the outer layer in two conduits. Conclusions. This study demonstrates good short-term patency rates of a newly designed three-layer vascular graft even in low-flow conditions in a sheep model. [ABSTRACT FROM AUTHOR]

Severe pulmonary hemorrhage in the newborn is an infrequent, but life-threatening, event. A newborn with persistent pulmonary hypertension and a large persistent ductus arteriosus and open foramen ovale presented with hypoxemia and progressive right heart failure shortly after birth, requiring veno-arterial extracorporeal membrane oxygenation (ECMO) support. Twenty minutes after the initiation of ECMO, the patient developed severe pulmonary hemorrhage refractory to conventional treatment. As a last resort, the endotracheal tube was clamped. After transport to the ECMO center, repeated attempts to open the endotracheal tube resulted in continued blood loss and the endotracheal tube was clamped for a total of 63 hours without any mechanical ventilation. On the third postnatal day, the endotracheal tube was reopened, large amounts of clot were removed by bronchoscopy and mechanical ventilation was resumed followed by improved general condition and favorable outcome. [ABSTRACT FROM AUTHOR]

Extracorporeal membrane oxygenation (ECMO) is an established tool for respiratory and circulatory support. In computed tomography, altered hemodynamics in ECMO patients requires special considerations and handling in contrast injection and its timing. In this article, we demonstrate changes in hemodynamics in ECMO patients captured on contrast-enhanced CT examinations and pitfalls in strategies for contrast injection in relation to the ECMO flow, cardiac function and the placement of ECMO cannulas. Contrast-enhanced CT of patients with ECMO requires prior knowledge of the ECMO cannulas, central venous lines, changes of hemodynamics induced by low cardiac output and the influence of adjustment of ECMO on blood flow in order to optimize injection of the contrast material and timing of the scan. Special considerations include temporary reduction of the ECMO flow, selection of the injection site and increasing volume or flow rate of the contrast material. [ABSTRACT FROM AUTHOR]

Aim. To compare the differences between medial and intercondylar infragenicular femoropopliteal prosthetic bypasses in terms of their midterm patency and limb salvage rates. Methods. Ninety-three consecutive patients with peripheral arterial disease who underwent a simple distal femoropopliteal bypass using a reinforced polytetrafluorethylene graft were included in this retrospective study. The bypass was constructed in the intercondylar route in 52 of the patients (group A) and in 41 in the medial route (group B). Results. Median observation time of the patients was 12.7 (IQR 4.6–18.5) months. There were 22 and 24 interventional or surgical procedures (angioplasty, stenting, thrombolysis, thrombectomy, or correction of the anastomosis) performed to restore patency of the reconstruction in groups A and B, respectively (p=0.14). The 20-month primary, assisted, and secondary patency rates and limb salvage rates were 57%, 57%, 81%, and 80% in group A compared to 21%, 23%, 55%, and 82% in group B (p=0.0012, 0.0052, 0.022, and 0.44, resp.). Conclusion. Despite better primary, assisted, and secondary patency rates in patients with a prosthetic infragenicular femoropopliteal bypass embedded in the intercondylar fossa compared to patients with the medial approach, there is no benefit in terms of the limb salvage rate and the number of interventions required to maintain patency of the reconstruction. [ABSTRACT FROM AUTHOR]

A wide range of viral agents is associated with the development of acute myocarditis and its possible chronic sequela, dilated cardiomyopathy (DCM). There is also increasing evidence that Borrelia burgdorferi ( Bb) is associated with DCM in endemic regions for Bb infection. This study sought to use electron microscopy to prospectively analyze the presence of viruses and Bb within the myocardium of 40 subjects with preserved left ventricular (LV) ejection fraction and 40 patients with new-onset unexplained DCM during the same time period. Virus particles were found within the myocardium of 23 subjects (58 %) of both cohorts studied, yet there was no statistically significant difference in virus family presence between those with DCM versus those with preserved LV systolic function. In contrast, Bb was detected only in those subjects with DCM (0 versus 5 subjects; p ˂ 0.05). Polymerase chain reaction was performed on samples from patients who were positive for Bb according to electron microscopy, and Bb was confirmed in 4 out of 5 individuals. Our results demonstrate that the prevalence of viral particles does not differ between subjects with preserved LV systolic function versus those with DCM and therefore suggests that the mere presence of a viral agent within the myocardium is not sufficient to establish a clear link with the development of DCM. In contrast, the presence of Bb was found only within myocardial samples of patients with DCM; this finding supports the idea of a causal relationship between Bb infection and DCM development. [ABSTRACT FROM AUTHOR]

Introduction: Lung agenesis is a rare disorder with a variable, but potentially very bad clinical course. It necessitates complex clinical management, especially in life-threatening situations. Case report: We describe a case of a 6-month-old girl with right lung agenesis who required venovenous extracorporeal membrane oxygenation (VV-ECMO) due to pneumonia complicated by exacerbated previously diagnosed left main bronchus stenosis. The stenosis was resolved by endobronchial intervention and X-ray-guided stent insertion, which enabled weaning from ECMO and was aimed at preventing such a life-threatening respiratory failure in the future. Unfortunately, even with the functional stent, the baby died 2 months post-procedure due to unresolvable bronchial spasms. Discussion: Despite high endobronchial stenting-related mortality in children, in cases where no effective pharmacological or surgical alternatives exist, stenting may be safely performed during VV-ECMO support and be a viable option to overcome critical respiratory failure caused by bronchial stenosis. [ABSTRACT FROM AUTHOR]