Q57008311
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The effects of a large arteriovenous fistula (AVF) on pulmonary perfusion remains to be elucidated. We aimed to study, for the first time, the real-time acute effects of a large AVF on regional distribution of pulmonary perfusion in a novel porcine model. Ten healthy swine under general anesthesia were studied. AVF was created by the connection of femoral artery and femoral vein using high-diameter perfusion cannulas. The AVF was closed and after 30 min of stabilization the first values were recorded. The fistula was then opened, and new data were collected after reaching stable state. Continuous hemodynamic monitoring was performed throughout the protocol. The following functional images were analyzed by electrical impedance tomography (EIT): perfusion and ventilation distributions. We found an increased cardiac output and right ventricular work, which was strongly correlated to an increased pulmonary artery mean pressure (r=0.878, P=0.001). The ventral/dorsal ratio of pulmonary perfusion decreased from 1.9+/-1.0 to 1.5+/-0.7 (P=0.025). The percentage of total pulmonary blood flow through the dorsal lung region increased from 38.6+/-11.7 to 42.2+/-10.4 (P=0.016). In conclusion, we have used EIT for the first time for studying the acute effects of a large AVF on regional distribution of pulmonary perfusion in a novel porcine model. In this new experimental model of hyperkinetic circulation caused by AVF, we documented an increased percentage of total pulmonary blood flow through the dorsal lung region and a more homogeneous perfusion distribution. Key words Arteriovenous fistula, Hyperkinetic circulation, Tissue perfusion, Animal model, Pulmonary blood flow.
- MeSH
- arteria pulmonalis diagnostické zobrazování patofyziologie MeSH
- arteriovenózní píštěl patofyziologie diagnostické zobrazování MeSH
- arteriovenózní zkrat MeSH
- plíce krevní zásobení diagnostické zobrazování MeSH
- plicní oběh * fyziologie MeSH
- prasata MeSH
- vena femoralis diagnostické zobrazování MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- MeSH
- hemolýza * MeSH
- katetrizační ablace * škodlivé účinky MeSH
- lidé MeSH
- srdeční katétry MeSH
- výsledek terapie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- dopisy MeSH
Veno-arterial extracorporeal membrane oxygenation (VA ECMO) is a technique used in patients with severe heart failure. The aim of this study was to evaluate its effects on left ventricular afterload and fluid accumulation in lungs with electrical impedance tomography (EIT). In eight swine, incremental increases of extracorporeal blood flow (EBF) were applied before and after the induction of ischemic heart failure. Hemodynamic parameters were continuously recorded and computational analysis of EIT was used to determine lung fluid accumulation. With an increase in EBF from 1 to 4 l/min in acute heart failure the associated increase of arterial pressure (raised by 44%) was accompanied with significant decrease of electrical impedance of lung regions. Increasing EBF in healthy circulation did not cause lung impedance changes. Our findings indicate that in severe heart failure EIT may reflect fluid accumulation in lungs due to increasing EBF.
- MeSH
- elektrická impedance MeSH
- hemodynamika MeSH
- koronární cirkulace fyziologie MeSH
- mimotělní membránová oxygenace škodlivé účinky metody MeSH
- modely nemocí na zvířatech MeSH
- plíce patofyziologie MeSH
- prasata MeSH
- respirační insuficience etiologie patologie MeSH
- srdeční selhání metabolismus patologie terapie MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Vývoj cévní náhrady pro nízké průtoky je aktuální otázkou. Autoři představují vlastní model hledání vývoje náhrady optimálních vlastností, které vycházejí z myšlenky převzetí charakteristiky biologického modelu – veny sapheny, a naprogramování těchto vlastností do modelu konstruované náhrady. Představovaná cévní náhrada se skládá ze tří částí – nevstřebatelného scaffoldu představujícího medii a dvou vstřebatelných kolagenních vrstev – pseudointimy a pseudoadventicie. Autoři představují základní metody fyzikálního testování (inflačně-extenzní test), stejně jako další postupy, které ovlivňují konečné vlastnosti vyvíjené protézy. Mezi takové patří tvrzení kolagenu, antitrombogenní ošetření vnitřního povrchu cévní náhrady a použití metody sterilizace. Testovaný prototyp byl úspěšně ověřen implantací na ovčím modelu.
The development of a low-flow vascular prosthesis is a very topical issue. The authors present a pathway for the development of a prosthesis with optimal properties based on the idea of mimicking the characteristics of a biological model (saphenous vein graft) and programming these properties in the model of the prosthetic substitute. The vascular prosthesis presented consists of three layers – a non-absorbable scaffold representing vascular “media”, and two absorbable collagen layers – pseudointima and pseudoadventitia. The basic methods of physical testing are presented – the single axis stretch test and inflation-extension test, as well as other procedures that affect the final properties. These include collagen curing, antithrombotic treatment of the inner layer and the use of sterilization methods. The designed new graft was successfully implanted in an ovine model.
- Klíčová slova
- cévní náhrada pro nízké průtoky, fyzikální testování,
- MeSH
- cévní protézy * MeSH
- lidé MeSH
- testování materiálů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
- přehledy MeSH
We compared graft outcome between two types of a novel composite three-layer carp-collagen-coated vascular graft in low-flow conditions in a sheep model. Collagen in group A underwent more cycles of purification than in group B in order to increase the ratio between collagen and residual fat. The grafts were implanted end-to-side in both carotid arteries in sheep (14 grafts in 7 sheep in group A, 18 grafts in 9 sheep in group B) and artificially stenosed on the right side. The flow in the grafts in group A decreased from 297±118 ml/min to 158±159 ml/min (p=0.041) after placement of the artificial stenosis in group A, and from 330±164ml/min to 97±29 ml/min (p=0.0052) in group B (p=0.27 between the groups). From the five surviving animals in group A, both grafts occluded in one animal 3 and 14 days after implantation. In group B, from the six surviving animals, only one graft on the left side remained patent (p=0.0017). Histology showed degradation of the intimal layer in the center with endothelization from the periphery in group A and formation of thick fibrous intimal layer in group B. We conclude that the ratio between collagen and lipid content in the novel three-layer graft plays a critical role in its patency and structural changes in vivo.
