Clinical Hemorheology and Microcirculation - Volume 43, issue 1-2

Authors: Pfister, K. | Rennert, J. | Uller, W. | Schnitzbauer, A.A. | Stehr, A. | Jung, W. | Hofstetter, P. | Zorger, N. | Kasprzak, P.M. | Jung, E.M.

Article Type: Research Article

Abstract: Objective: Is Contrast Harmonic Imaging (CHI) comparable to computed tomography angiography (CTA) scan in detecting and characterizing suspected endoleaks after endovascular abdominal aneurysm repair in a non-selected group including reintervention procedure and branched endografts in daily practice? Material/methods: In a prospective study computed tomography angiography (CTA) and contrast-enhanced ultrasound (CEUS) were performed in 30 consecutive patients (26 males, 4 females, mean age: 72 years, range: 38–87) with suspected endoleaks in follow-up (mean 13 months, range: 1–95) after endovascular abdominal aneurysm repair or procedure in dissection or penetrated ulcer of the aorta (25 infrarenal, 5 suprarenal stent grafts, mean aortic …diameter 56 mm, range: 27–98). CTA was supposed to be gold standard for determining the presence of endoleaks (multislice CT, collimation 16 × 0.75 mm, 100 ml of iodized contrast agent bolus). Ultrasonography used a multi-frequency probe (1–4 MHz) with the modalities of colour coded Doppler sonography (CCDS), power Doppler (PD) combined with contrast enhancement and the technique of contrast harmonic imaging (CHI) and low mechanical index (MI < 0.2). 2.4 ml of SonoVue® (Bracco, Altana Pharma GmbH, Italy) were administered to each patient intravenously as a bolus injection. Results: Out of 30 patients, 21 endoleaks were identified in CTA (6 type I or III, 15 type II), 22 in CHI. Thus, sensitivity for CHI was therefore 99%, its specificity 85% (Spearman correlation coefficient (CC) 0.92). In follow-up the localizations of endoleak type I or III exclusively detected by CHI were confirmed as true positive by angiography. Due to its dynamic characteristic CHI seemed to be more helpful in characterization of endoleaks than CTA. In case of a rupture after reintervention a type III endoleak leads to prompt intervention before receiving the result of the CT scan. Altogether, CHI failed to identify 1 combined type I and II endoleak (sensitivity 0.99). Both, CCDS and PD were positive only in 6/30 patients (CC 0.33 and 0.39). Interestingly the application of contrast agent doubles the detection rate of endoleaks (12/30) in CCDS and PD (CC 0.39). Conclusion: Contrast harmonic imaging (CHI) compared to computed tomography angiography (CTA) accurately depicts endoleaks after endovascular abdominal aneurysm repair and stent-graft procedure in dissected and ulcerated aorta. It seems to be superior in characterization of the type of endoleaks and can be established in order to reduce iodized contrast agent and radiation exposure in follow-up. In contrast to CTA scan CHI can be offered to patients with chronic renal insufficiency and allows a dynamic examination and a perfusion analysis. Show more

Keywords: Contrast-enhanced ultrasound, endovascular abdominal aneurysm repair, endoleak, surveillance

DOI: 10.3233/CH-2009-1226

Citation: Clinical Hemorheology and Microcirculation, vol. 43, no. 1-2, pp. 119-128, 2009

Authors: Clevert, D.-A. | Horng, A. | Clevert, D.-A. | Jung, E.M. | Sommer, W.H. | Reiser, M.

Article Type: Research Article

Abstract: Purpose: To evaluate the diagnostic results of different ultrasound techniques: B-scan, color-coded Doppler sonography (CCDS) and contrast-enhanced ultrasound in the diagnosis of abdominal aortic dissection in comparison to multislice computed tomography (MS-CT). Materials and methods: Between March 2006 and December 2008, 35 patients (28 males, 7 females) with a mean age of 58 years (range 37–87 years) with abdominal aortic dissection and 15 patients (11 males, 4 females) with a mean age of 53 years (range 42–78 years) without abdominal aortic dissection as a control group were examined with B-scan, CCDS and contrast-enhanced ultrasound (CEUS) after injection of 1.0–1.2 …cc of SonoVue (Bracco, Italy). The examinations were performed using a Sequoia 512 (Siemens/Acuson, Mountain View) system with CPS software. Standardized MS-CTA using a 16 or 64 row scanner (Somatom Sensation 16 or 64, Siemens Medical Systems, Forchheim, Germany) served as the reference standard. Results: The sensitivity of B-scan and CCDS for detecting abdominal aortic dissections were both 23/35 (68%); for contrast-enhanced ultrasound it was 34/35 (97%). Dissection membrane, differentiation of true and false lumen and flow direction within the true and false lumen were better detected by CEUS than by CCDS. The lack of angle dependence of the US probe and lack of flow and pulsations artifacts in CEUS made the examination procedure easier. All findings were confirmed by MS-CT. Conclusion: With contrast-enhanced ultrasound, diagnostic accuracy sensitivity and specificity for the diagnosis of abdominal aortic dissections is improved as compared to B-scan and CCDS. Dissection membrane and flow within the true and false lumen are clearly differentiated by CEUS. Thus CEUS is a promising alternative for patients whose condition does not allow an examination by CTA. Show more

Keywords: Dissection, contrast-enhanced ultrasound, MS-CT

DOI: 10.3233/CH-2009-1227

Citation: Clinical Hemorheology and Microcirculation, vol. 43, no. 1-2, pp. 129-139, 2009

Authors: Girlich, C. | Jung, E.M. | Iesalnieks, I. | Schreyer, A.G. | Zorger, N. | Strauch, U. | Schacherer, D.

Article Type: Research Article

Abstract: Patients with inflammatory bowel disease (IBD) often undergo several radiologic imaging studies, which – with the exception of magnetic resonance imaging (MRI) and B-scan ultrasound (US) – subject patients to ionizing radiation. With contrast enhanced ultrasound microvascular imaging of the bowel is possible. Hence, the aim of our study was to assess the perfusion pattern of inflamed bowel walls in Crohn's disease compared with healthy volunteers quantitatively using a specific quantification software. We evaluated 4 volunteers and 20 patients with proven Crohn's disease, who went through an active episode based on clinical symptoms and complementary imaging by MRI (19 …patients) and computed tomography (1 patient), respectively, with dynamic contrast-enhanced ultrasound (CEUS) using a second generation contrast agent (SonoVue® , Bracco, Germany). Retrospectively, we applied the quantification software Qontrast® (Bracco, Italy) to obtain contrast-enhanced sonographic perfusion maps for each lesion. Patients had significant higher peak values (median 46.86, lower quartile 37.91, upper quartile 53.20) and significant higher regional blood volume (median 2133.65, lower quartile 1202.90, upper quartile 2820.44) than volunteers. Considering the very low peak value of the healthy, it is easy to understand that the time-to-peak was significantly shorter in the volunteers (median 4.45, lower quartile 1.82, upper quartile 6.88) than in the patients (median 12.15, lower quartile 9.18, upper quartile 15.74). Our study showed clear differences between inflamed and normal bowel wall vascularity regarding all perfusion parameters. These results show that a quantitative assessment of the bowel wall vascularisation and inflammation, respectively, is possible. The software used here enables us to collect data, not only in a semi-quantitative but also in a reproducible, quantitative manner which is comparable with the evaluation of CT or MRI generated data. Show more

Keywords: Contrast-enhanced ultrasound, Crohn's disease, quantitative perfusion analysis, inflammatory bowel disease

DOI: 10.3233/CH-2009-1228

Citation: Clinical Hemorheology and Microcirculation, vol. 43, no. 1-2, pp. 141-148, 2009

Authors: Franke, R.P. | Fuhrmann, R. | Hiebl, B. | Mrowietz, C. | Jung, F.

Article Type: Research Article

Abstract: The permeability of a material is described by the amount of substances (gases, liquids, particles) passing through pores and/or interstices of the material in a certain time. In medicine and biotechnology the permeability is given usually as the amount of water (ml × cm−2 × min−1 ) permeating per area and time unit through the material. Vascular prostheses are described e.g. as high porous prostheses (e.g. Dacron™: 1500–4000 (ml × cm−2 × min−1 )) or as low porous prostheses (e.g. ePTFE: 200–1000 (ml × cm−2 × min−1 )). The permeability of blood capillaries is characterized by …the exchange of nutrients, metabolites and breathing gases. Capillary permeability and the transport of the permeates through tissues are the key processes for the supply of organs and tissues where especially the protein transport through tissues is described by diffusive and/or convective terms. The vascular permeability is governed by the permeability of the intimal endothelial cells. The major influence is exerted by the interendothelial binding which can change drastically in a very short time. This is demonstrated by the fast development of interstitial lung oedema in case of septical shock. The permeability is an integral indicator of tissue and organ function. It is possible to assess the permeability of native and engineered tissues precisely with a recently developed system. First results will be shown. Show more

Keywords: Vascular permeability, water, culture medium, endothelial cells, nylon 6,6, PETP

DOI: 10.3233/CH-2009-1229

Citation: Clinical Hemorheology and Microcirculation, vol. 43, no. 1-2, pp. 149-155, 2009

Authors: Hoepken, S. | Fuhrmann, R. | Jung, F. | Franke, R.P.

Article Type: Research Article

Abstract: A variety of medical grade polymeric materials are used in tissue engineering and biomedical technology. Dense non-porous polymeric foils were used as substrates for endothelial cell layers. Half a the test samples (polymers and control materials) were seeded with bovine corneal endothelial cells (BCEC) which more or less covered the substrates with an extracellular matrix (ECM) in the consecutive culturing period. Afterwards the ECM covered as well as the uncovered materials were seeded with human umbilical venous endothelial cells (HUVEC). HUVEC seeded samples were cultured either under static or under dynamical conditions in a cone/plate rheometer with a mean low …arterial shear stress of 8.2 dyn/cm2 to simulate the flow conditions in a coronary vein graft. With the exemption of polyvinyl chloride all other materials could be coated with ECM at least partially. Under static conditions the best results with respect to complete coverage with ECM and HUVEC were seen on polyester and polyurethane. Under shear load, however, the complete HUVEC layer together with the ECM detached from the polymer surface within a short time. ECM and HUVEC remained no longer than 43 minutes on anyone of the materials tested. The materials as supplied and tested were clearly not appropriate as implants in contact to the flowing blood. Show more

Keywords: Endothelial cells, extracellular matrix, shear stress, vascular graft, polymers, biomedical materials

DOI: 10.3233/CH-2009-1230

Citation: Clinical Hemorheology and Microcirculation, vol. 43, no. 1-2, pp. 157-166, 2009

Authors: Leithäuser, B. | Mrowietz, C. | Hiebl, B. | Pindur, G. | Jung, F.

Article Type: Research Article

Abstract: Background: Oral anticoagulants are routinely used for prevention of thromboembolism in cardiac, arterial or venous diseases. Hemorrhages are serious treatment complications, frequently occurring under long-term and/or high-dose regiments. From animal experiments it is known that coumarin-type anticoagulants may cause capillary dilatation and increased permeability, red blood cell extravasation and punctate bleeding. Controlled human trials are lacking. Methods: 31 patients under oral anticoagulation were examined by video capillary microscopy. 52 patients with comparable diseases and treatment but without oral anticoagulation served as controls. Nailfold capillaries of four fingers of each hand were examined and analyzed off-line according to the following …criteria: (1) numbers of capillaries investigated, (2) numbers of capillary bleedings, and (3) bleeding incidence (bleedings per 100 capillaries). Results: In 23 out of 31 patients (74.2%) capillary bleedings were observed. The bleeding incidence ranged from 0.33 to 4.29 per 100 capillaries. In contrast, only 4 out of 52 controls were detected with capillary bleedings (2.1%, p<0.001). The bleeding incidence was 0.34–2.41. In patients on anticoagulation there was no correlation between the number of capillary bleedings and the INR or Quick values. During a two year follow-up of patients on oral anticoagulation no significant difference was found in terms of clinically obvious bleedings in patients with or without capillary bleedings. Conclusion: This study shows that capillary bleedings can be demonstrated in patients on oral anticoagulation. Bleedings occur independent of the INR-value. Thus, other factors than the vitamin-k-dependent coagulation effect seem to be causal for the damage of microvessels. Further, the evidence of capillary bleedings is not a prognostic indicator for future hemorrhage. Show more

Keywords: Microcirculation, capillary, bleeding, cumarin

DOI: 10.3233/CH-2009-1231

Citation: Clinical Hemorheology and Microcirculation, vol. 43, no. 1-2, pp. 167-171, 2009

Authors: Hiebl, B. | Mrowietz, C. | Braune, S. | Franke, R.P. | Plendl, J. | Jung, F.

Article Type: Research Article

Abstract: Several methods are available today for the investigation of microcirculation in animal models, but they can be invasive and time-consuming depending on the area investigated. In particular, non-invasive methods that can be conducted rapidly and without dye or tracer injections are in demand. The cutaneous microcirculation can be easily studied in the dorsal corium limbi of the third toe of the porcine forelimb using intravital microscopy – analogous to nail fold capillary microscopy in humans. The capillary microscopy system consists of a reflected-light microscope with a cold light source, green and infrared filters and a video camera. The video …sequences were recorded using the image capture system Framegrabber (Imagenation PXC-200) and a PC (with an Intel Core 2 Duo processor, 1024 MB RAM, 160 GB hard disk, Windows XP Pro), and stored via a DVD recorder (Panasonic LQ-MD800). Quantification of capillary erythrocyte flow velocities was performed using the computer-assisted image analysis system Cap Image Version 8.5 which includes a movie tool as a video sequence storage medium. The method allows estimation of capillary density and tortuosity as well as capillary circulation in the anesthetized pig within a few minutes. First measurements were made after anesthesia induction followed by further measurements during anesthesia maintenance (3 minutes each). No differences in capillary circulation were found. The present method is thus very well suited for long-term microcirculation measurements in pigs, e.g., to evaluate therapeutic interventions in the ischemic limb model. Show more

Keywords: Microcirculation, animal model, capillary microscopy

DOI: 10.3233/CH-2009-1232

Citation: Clinical Hemorheology and Microcirculation, vol. 43, no. 1-2, pp. 173-179, 2009

Authors: Franke, R.P. | Fuhrmann, R. | Hiebl, B. | Jung, F.

Article Type: Research Article

Abstract: Besides the desirable effect of roentgen ray absorption radiographic contrast media (RCM) can also have varying adverse effects. Under discussion, as a possible cause, are microcirculatory disorders resulting from morphological alterations in erythrocytes and endothelial cells. Therefore, the contrast media-induced release of vasoactive substances (prostacyclin, endothelin-1, and nitric oxide (NO)) from human endothelial cells (HUVEC) induced by two commercially available RCMs (Iodixanol 320, Iomeprol 350) was tested in a controlled in-vitro study. The results show that RCMs lead to endothelial cell trauma in vitro, which is apparent in the release of prostacyclin and endothelin-1, while NO release was …not affected. The endothelin-1 release after incubation with Iodixanol was similar to the release in the control cultures. In comparison, lower endothelin-1 levels were measured in the cultures incubated with Iomeprol at all 3 time points indicating a more significant cell trauma. Prostacyclin release – also an indicator of traumatization of endothelial cells – increased after addition of both contrast agents. The highest release was found after incubation with Iomeprol 350. Show more

Keywords: Endothelin, prostacyclin, NO, radiographic contrast media, primary human endothelial cells

DOI: 10.3233/CH-2009-1233

Citation: Clinical Hemorheology and Microcirculation, vol. 43, no. 1-2, pp. 181-187, 2009