Robert Vlachovský

Automatic identification and validation of planar collagen organization in the aorta wall with application to abdominal aortic aneurysm.

Arterial physiology relies on a delicate three-dimensional (3D) organization of cells and extracellular matrix, which is remarkably altered by vascular diseases like abdominal aortic aneurysms (AAA). The ability to explore the micro-histology of the aorta wall is important in the study of vascular pathologies and in the development of vascular constitutive models, i.e., mathematical descriptions of biomechanical properties of the wall. The present study reports and validates a fast image processing sequence capable of quantifying collagen fiber organization from histological stains. Powering and re-normalizing the histogram of the classical fast Fourier transformation (FFT) is a key step in the proposed analysis sequence. This modification introduces a powering parameter w, which was calibrated to best fit the reference data obtained using classical FFT and polarized light microscopy (PLM) of stained histological slices of AAA wall samples. The values of w = 3 and 7 give the best correlation (Pearsons correlation coefficient larger than 0.7, R 2 about 0.7) with the classical FFT approach and PLM measurements. A fast and operator independent method to identify collagen organization in the arterial wall was developed and validated. This overcomes severe limitations of currently applied methods like PLM to identify collagen organization in the arterial wall.

Infrared thermography as option for evaluating the treatment effect of percutaneous transluminal angioplasty by patients with peripheral arterial disease.

Aim of this study was to evaluate the possible use of infrared thermography as a supplementary method to the ankle-brachial index used in assessing the treatment effect of percutaneous transluminal angioplasty. The study included 21 patients, mean age was 60.22 years. Healthy control group included 20 persons, mean age was 55.60 years. Patients with symptomatic peripheral arterial disease (Fontaine stages I–III) were admitted for endovascular treatment by percutaneous transluminal angioplasty. Thermal images and ankle-brachial index values were obtained before and after treatment by percutaneous transluminal angioplasty. Median temperature change in the treated limb was 0.4℃, for non-treated limb was –0.5℃. The median value of ankle-brachial index in the treated limb increased by 0.17 from 0.81 after the procedure. The median value of ankle-brachial index in the non-treated limb decreased by 0.03 from the value of 1.01. Significant difference between treated limb and non-treated limb in change of ankle-brachial index was found with p value = .0035. The surface temperature obtained by the infrared thermography correlates with ankle-brachial index. We present data showing that the increase of ankle-brachial index is associated with increase of skin temperature in the case of limbs treated by percutaneous transluminal angioplasty. Our results also suggest potential of the use of infrared thermography for monitoring foot temperature as a means of early detection of onset of foot ischemic disorders.

Organization model for allotransplantations of cryopreserved vascular grafts in Czech Republic

The transplantation of fresh or cryopreserved vascular allografts in patients with a prosthetic graft infection or critical limb ischemia is necessary for their limb salvage and, in many cases, represents a lifesaving procedure. While transplantation of fresh allografts has a long history in the Czech Republic, the standard use of cryopreserved vascular allografts was introduced into the clinical practice in 2011 as a result of the implementation of EU Directive 2004/23/EC into national legislation (Human Cell and Tissue Act No. 296/2008 Coll.). The authors present an organizational model based on cooperation between the majority of Czech Transplant Centers with a tissue establishment licensed by the national competent authority. In various points, we are addressing individual aspects of experimental and clinical studies which affect clinical practice. Based on experimental and clinical work, the first validation of cryopreserved arterial and venous grafts for clinical use was performed between 2011 and 2013. The growing number of centers participating in this programme led to a growing number of patients who underwent transplantation of vascular allografts. In 2015 the numbers of transplanted fresh versus cryopreserved allografts in the Czech Republic were almost equal. Cooperation of the participating centers in the Czech Republic with the licensed Tissue Establishment made it possible to achieve a full compliance with the European Union Directives, and harmonized national legal norms and assured a high quality of cryopreserved vascular allografts.

Long-term patency of a RaK collagen vascular prosthesis -single centre results during a 10 year follow-up

The aim of this retrospective study was to evaluate the results of vascular operations based on the RaK prostheses, with a particular attention paid to their long-term patency. The study included 105 patients who were operated on in the period from 1992 to 1996. Vascular surgery was performed in the aortofemoral area and the underlying diagnoses were Leriche syndrome, asymptomatic abdominal aortic aneurysm, iliac artery stenosis or occlusion and symptomatic abdominal aortic aneurysm. During the mean follow-up time of 96 months (range 28-144), 8 patients (7.6 %) were lost to follow-up and 23 patients (21.9 %) died. At 12, 36, 60 and 120 months after surgery, the prostheses were patent in 99 %, 98 %, 93 % and 89 % of the patients, respectively. It is concluded that the RaK collagen prosthesis is the device of high quality and parameters comparable with the other types of knitted vascular prostheses currently used (Tab. 3, Fig. 4, Ref. 17).

Follow-up and its importance for long-term pedal bypass functionality.

Abstract Pedal bypasses, for salvage of a critically ischaemic limb, demonstrate excellent long-term outcomes. However, regular follow-up of patients and timely detection and treatment of a contingent haemodynamically significant bypass stenosis, which could cause its thrombosis, are prerequisites. The authors report a case of femoropedal bypass graft in which regular duplex follow-up detected critical stenoses at 18 months and at 36 months. Patch-angioplasty (at 18 months) and percutaneous balloon angioplasty (at 36 months) preserved the long-term patency of this pedal bypass graft.