Histological Justification for the Need of Radiofrequency Ablation of Pulmonary Arteries in Patients with High-Grade Secondary Pulmonary Hypertension.

The aim of the study was to perform a histological assessment of the effectiveness of radiofrequency exposure for circular denervation of the pulmonary artery in patients with secondary high pulmonary hypertension. Materials and Methods: The study was carried out on the autopsy material derived from non-operated patients. Three groups were formed. The experimental group included the material (207 histological samples) from the patients with chronic high pulmonary hypertension arising on the background of mitral heart disease. The samples of this group were exposed to circular radiofrequency ablation. In the comparison group, we used autopsy material (24 samples) obtained from the patients with high pulmonary hypertension. The control group included material (35 samples) from the patients without pulmonary hypertension who died from causes not associated with cardiovascular diseases. The samples of the comparison and control groups were not exposed to radiofrequency.Visual evaluation of the damage to the vascular wall was performed after hematoxylin and eosin staining, according to Van Gieson. Damage to the nerve plexuses was evaluated after their impregnation by silver salts. To assess the degree of damage to the vascular wall on the stained sections, a scoring method of semi-quantitative analysis of the observed pathological processes (fibrinoid necrosis, metachromasia, karyorrhexis, karyolysis, fibrinoid and mucoid swelling, lipid presence) was used. Silver salt impregnation allowed visualizing damage to the reticular fibers, trunks and endings of peripheral nerve fibers. Results: The mean optical density of the ablation group was statistically significantly lower than in the comparison and control groups (p<0.001). The mean specific area of tissue dissociation was higher in the "marginal zones" of the ablated sections, under pronounced mechanical compression in these areas. The difference in the mean areas of the argentophilic samples of the ablation and comparison and control groups was expressed in a lower percentage of argentophilic fibrous structures (p<0.05). At the same time, the highest concentration of argentophilic structures was observed in the comparison group, which points to a bigger content of nerve fiber structures in the patients with high pulmonary hypertension. Conclusion: The results of the histological study demonstrated the feasibility of radiofrequency ablation of the pulmonary arteries in patients with high-grade secondary pulmonary hypertension. Radiofrequency denervation leads to the destruction of the sympathetic ganglia in the adventitial layer of the pulmonary arteries, which are responsible for the spasm of the precapillary bed of the pulmonary circulation, which promotes vasodilation, an increase in the vascular bed, and, as a result, a reduction in pulmonary hypertension.

[Effectiveness of the Cox Maze-IV Procedure in Cardiac Surgery Patients With Atrial Fibrillation].

Aim Analyzing a 5-year experience of surgical treatment of cardiosurgical patients with atrial fibrillation (AF).Material and methods The study analyzed results of surgical treatment with extracorporeal circulation in 132 patients with AF who underwent the Maze-IV procedure using a radiofrequency ablator with transmurality feedback from 2013 through 2018.Results Two fatal outcomes were observed in the study group. These outcomes took place in the early postoperative period and were associated with progressive acute heart failure in patients with repeated surgery for mitral valve restenosis. 61.2% of the patients had no AF. Recurrent AF was observed during the first three years after surgery in association with withdrawal of the antiarrhythmic medication, which confirmed a need for long-term antiarrhythmic therapy. Analysis of risk factors for AF relapse identified significant predictors, including left ventricular dilatation larger than 5.5 cm at baseline and more than two-year duration of a history of arrhythmias.Conclusion The Maze-IV procedure proved an effective and safe method of surgical treatment in AF patients with acquired heart defects and ischemic heart disease, which allowed maintaining sinus rhythm in 61.2% of patients for 5 years. Preventive amiodarone saturation reduced the risk of AF relapse by 24.2 % (p=0.038) and incidence of postoperative arrhythmic complications by 34.9 % (p=0.008) in cardiosurgical patients.

[Changes of the tissues and of regional lymph nodes in rats with chronic inflammatory process treated with interleukin-2].

The structure of Wistar rat subcutaneous adipose tissue and axillary (regional) lymph nodes (LN) was studied by the methods of light microscopy after the subcutaneous implantation of the fragments of silicone mammary implant in the area of right scapula in animals treated with interleukin-2 (IL-2). Subcutaneous implantation of sterile silicone plates to rats was found to induce chronic granulomatous inflammatory process with the formation of connective tissue capsule. Implants placement to rats treated with IL-2 resulted in the formation of a thicker capsule with the signs of sclerosis, fibrosis and hyialinosis; all the capsular structures were heavily infiltrated with macrophages, which contained phagocytozed silicone fragments. After the introduction of silicone implants, the volume of the capsule and connective tissue in the regional LN progressively increased, while after IL-2 treatment the intensity of sclerotic processes was significantly decreased. The relative area of lymphoid nodules without the germinal centers in LN sections was increased 1 month following the induction of chronic inflammatory process in rats treated with IL-2, but by 6 months the proportion of nodules both with or without germinal centers become less, as compared to the initial data.

[The structure of the rat lymph nodes draining purulent inflammation region after interleukin-2 treatment].

The structure of rat lymph nodes regional to the purulent wound under the conditions of interleukin (IL-2) treatment was investigated by the methods of light microscopy. In the lymph nodes from intact animals, the cortical plateau was found to become diminished with the simultaneous paracortical zone expansion. In the regional lymph nodes from rats with an untreated purulent wound, the relative dimensions of cortical plateau were decreased because of expansion of the medullary structures. Lymphoid parenchyma and the sinuses of lymph nodes contained erythrocytes, the numbers of immuno- and plasmoblasts, macrophages and neutrophilic granulocytes were increased. IL-2 treatment in animals with a purulent inflammatory reaction secured the greater integrity of structure of these organs and of cytoarchitecture of their various zones. However, the administration of this cytokine resulted in increased vascular permeability and enhanced the probability of allergic reaction development, which requires the development and application of prophylactic measures of the specified side effects and complications.