C. Mrowietz

Effect of X-Ray Contrast Media on Blood Flow Properties after Coronary Angiography

In vitro studies suggest that ionic and nonionic X-ray contrast media have different effects on rheological parameters. The risk of thrombotic complications in coronary interventions was reported to be lower using ionic contrast media. The aim of the present study was to compare the effects of different types of contrast media on rheological parameters after coronary angiography. Sixty patients were randomized to four groups: ioxaglate 320 (dimeric, ionic, n = 18), iomeprol 400 (monomeric, nonionic, n = 12), iobitridol 350 (monomeric, nonionic, n = 12), and iodixanol 320 (dimeric, nonionic, n = 18). Blood samples were collected via the side port of the arterial sheath immediately before and at the end of coronary angiography. In our study, all types of contrast media caused a significant decrease in haematocrit (Hct), plasma viscosity (PV), erythrocyte aggregation (EA), and in the platelet reactivity index (PRI). The most pronounced decrease in Hct was found using the ionic dimer ioxaglate. There were no significant differences between the contrast media with respect to their effects on PV, EA, and PRI.

Critical hematocrit and oxygen partial pressure in the beating heart of pigs

In cardiac surgery the substitution of lost blood volume by plasma substitutes is a common therapeutical approach. None of the currently available blood substitutes has a sufficient oxygen transport capacity. This can limit the functional integrity of the myocardium known as highly oxygen consumptive. The study was aimed to get information about the minimal hematocrit, also known as critical hematocrit (cHct), which guarantees a stable and adequate oxygen partial pressure in the myocardium (pO2). In adult female pigs (n=7) the hematocrit was reduced by isovolemic blood dilution with an intravenous infusion of isotonic 4% gelatine polysuccinate solution, The substituted blood volume ranged between 3000ml and 7780ml (mean: 5254±1672ml). In all animals the pO2 of the myocardium of the beating heart and of the resting skeletal muscle increased until blood dilution resulted in a Hct decrease down to 15%. Further blood dilution resulted in a decrease of the pO2. Only after the Hct was <10% the pO2 was lower than before blood dilution and accompanied by a lethal ischemia of the myocardium. These data indicate a cHct of about 10% in the pig animal model.

Activation of Peroxisome Proliferator–Activated Receptor-δ as Novel Therapeutic Strategy to Prevent In-Stent Restenosis and Stent Thrombosis

Objective—Drug-eluting coronary stents reduce restenosis rate and late lumen loss compared with bare-metal stents; however, drug-eluting coronary stents may delay vascular healing and increase late stent thrombosis. The peroxisome proliferator–activated receptor-delta (PPAR&dgr;) exhibits actions that could favorably influence outcomes after drug-eluting coronary stents placement. Approach and Results—Here, we report that PPAR&dgr; ligand–coated stents strongly reduce the development of neointima and luminal narrowing in a rabbit model of experimental atherosclerosis. Inhibition of inflammatory gene expression and vascular smooth muscle cell (VSMC) proliferation and migration, prevention of thrombocyte activation and aggregation, and proproliferative effects on endothelial cells were identified as key mechanisms for the prevention of restenosis. Using normal and PPAR&dgr;-depleted VSMCs, we show that the observed effects of PPAR&dgr; ligand GW0742 on VSMCs and thrombocytes are PPAR&dgr; receptor dependent. PPAR&dgr; ligand treatment induces expression of pyruvate dehydrogenase kinase isozyme 4 and downregulates the glucose transporter 1 in VSMCs, thus impairing the ability of VSMCs to provide the increased energy demands required for growth factor–stimulated proliferation and migration. Conclusions—In contrast to commonly used drugs for stent coating, PPAR&dgr; ligands not only inhibit inflammatory response and proliferation of VSMCs but also prevent thrombocyte activation and support vessel re-endothelialization. Thus, pharmacological PPAR&dgr; activation could be a promising novel strategy to improve drug-eluting coronary stents outcomes.

Qualität von Erythrozytenkonzentraten aus rheologischer Sicht

The present study deals with the question if rheological properties of erythrocyte concentrates (EC) are altered during the storage duration. As a parameter of erythrocyte function cell deformability

Rheologische und kapillarmikroskopische Größen zur Diagnostik des von-Willebrand-Jürgens-Syndroms

In future, the capillary microscopy may add to the spectrum of differential diagnosis finding in haemostaseological and angiogical centres as a screening test. Especially the fast and simple observation of the capillary morphology with changes such as capillary dilatations, capillary bleeding (the easiest case, extravasal cells, but also fresh bleeding at the summit of the capillary) and simultaneous findings of torqua-tion of the capillaries seem to be very sensitive for the diagnosis of the von Willebrand-Jurgens syndrome – according to the data collected until now.

Hämorheologische, mikro- und makrozirkulatorische Effekte einer Infusion von 500 ml 6%iger mittelmolekularer Hydroxyäthylstärke (Haes 200000/0,5)

In einer offenen Untersuchung an 10 anscheinend gesunden Probanden wurde der Einfluβ einer hypervolamischen Hamodilution (Infusion von 500ccml Hydroxyathylstarke 200000/0,5 6% innerhalb einer Stunde)