Purpose of study Using an original device for modeling of intra-arterial blood circulation, to study the features of intravascular hemodynamics with a regular heart rhythm and with various rhythm disturbances. Material and methods We used an original device developed by us to simulate intra-arterial circulation (Document of invention No. RU 202780 U1). The main part of the device is a glass tube of a rotameter with a length of 365 mm, an inlet end with a diameter of 20 mm, an outlet end of 16.5 mm, which is a model of an arterial vessel. Flexible silicone tubes are attached to the rotameter on both sides, with free ends connected to an electric pump, with various modes of operation (imitation of pulse waves with regular rhythm, premature ventricular contractions (PVCs), atrial fibrillation (AF). An aqueous solution of glycerin was introduced into a closed system diluted with water corresponding to the viscosity of the blood. A 5 mm long silk thread was alternately installed inside the tube, an intravascular piezoelectric crystal pressure probe connected to an oscilloscope. Also it was injected inside the tube a dye - clerical ink. Results With electric pump, we simulated the spreading of the pulse wave in regular heart rate, PVCs and AF. We observed the effect of a pressure wave (deflection of a silk thread, the appearance of a turbulent flow when using a dye) on the walls of the rotameter, with the formation of standing, reflected waves during the PVCs and AF. The pressure probe registered an increase in pressure inside the tube during the spread of the 1st post-extrasystolic contraction wave up to 58%, the wave after a long pause of more than 2 seconds with AF by 44% compared to the regular rhythm. Conclusion A device for modeling of intra-arterial circulation allows a wide range of experimental work in cardiology, normal and pathological physiology, and biophysics. FUNDunding Acknowledgement Type of funding sources: None.
Objectives to determine the hemodynamic changes within arterial vessels in different variants of extrasystole, to analyze whether extrasystole is an additional risk factor for the development of atherosclerosis. Material and methods. The study included 286 patients (175 men and 111 women) with extrasystole of more than 3000 per day and 88 patients with extrasystole of less than 3000 per day as a control group. When selecting eligible patients for the study, we tried to minimize the impact of traditional risk factors of atherosclerosis. The presence of cardiocerebral complications in medical history was also considered. The examination methods used in the study are electrocardiography, phonocardiography, 24-hour electrocardiography monitoring, Doppler ultrasound of the brachiocephalic vessels, lower extremities arteries, renal arteries, transthoracic or transesophageal echocardiography. Stress echocardiography was performed if indicated; as well as renal artery angiography, coronary angiography, computed tomography of the brain with angioprogram. When performing a biochemical blood test, the lipid spectrum and hemostasiogram were necessarily determined. All patients underwent left ventricular apexcardiography, as well as sphygmography, recorded on arteries of elastic type (a. Carotis communis) and muscular-elastic type (a. Tibialis posterior). The clinical examinations were confirmed and modeled using the original "Device for modeling of intra-arterial circulation", developed by us (RF patent No. 202780 dated 05.03.2021). Results. We determined an increase in the main parameters of the heart biomechanics and the kinetics of the main arteries in the 1st post-extrasystolic wave in patients with various types of extrasystole with the following pattern: the earlier extrasystole had appeared in the cardiocycle, the greater was the increase in the parameters under observation. A universal concept of hydraulic shock and possible cases of its formation were described. Conclusion. Extrasystole is an additional risk factor for the onset and progression of atherosclerosis. Hydraulic shock during the passage of the 1st post-extrasystolic wave is a powerful traumatic factor for the walls of the arteries, which can lead to the formation of an atherosclerotic process.
Objectives to study the mechanism of restenosis after the intra-arterial stenting using the original device for modeling of intra-arterial blood flow. Material and methods. To perform the experiment, we have created the original device simulating the intra-arterial blood flow. A glass tube of rotameter was the imitation of the arterial vessel. The closed system was filled with the liquid imitating blood, specifically the solution of glycerin the same viscosity as the human blood plasma. Using our original model of intra-artetial blood flow, we were able to study the intra-arterial hemodynamics under different conditions of cardiovascular system functioning, including arrhythmias. Results. In extrasystolic arrhythmia, during the spread of the first post-extrasystolic wave, we observed the intensive impact of pressure wave (the indicator was the silk thread) on the vessel walls with forming of reflected and standing waves. Putting the piezo crystal probe of pressure inside the tube, we verified our observations. The increase of pressure during the spread of the first post-extrasystolic wave in multiple measurements had a mean value of 160% in comparison with the pressure during the regular heart rhythm. Conclusion. The hydraulic shock appears during the spread of the first post-extrasystolic wave in the arterial vessel. Its effect on hemodynamics grows in case of the frequent extrasystoles and allorhythmia. The mechanical impact of hydraulic shock in extrasystoles can be the starting point of the restenosis onset and progressing in the intra-arterial stent.
Aim. To determine the changes of parameters of heart biomechanics and kinetics of arteries, to reveal the adverse events of first post-extrasystolic contraction.Materials and methods. In our investigation we included 286 patients. We excluded all the main traditional risk factors of the atherosclerosis. All the patients were branched into two main groups in accordance to the quantity of extrasystoles per 24 hours: I group – less than 3000, II group – more than 3000 extrasystoles per 24 hours. We took the data about complaints, anamnesis, made laboratory and instrumental investigations to reveal the character and severity of atherosclerotic process.Results. We determined that the atherosclerotic process was more advanced and more often in the group II. Also the atherosclerosis was more severe in patients with extrasystoles in the phase of cardiocycle before opening of the mitral valve and before the transmitral blood flow peak. The parameters (acceleration, speed, power, work) that were calculated by apexcardiography and sphygmography increased with the further tendency: if earlier extrasystole appears in cardiocycle, than more changes were observed.Conclusion. The first post-extrasystolic contraction causes the increase of all parameters of heart biomechanics and kinetics of vessels and can be an additional factor of progressing of atherosclerosis.
Background. Up to 45% of ischemic strokes are cryprogenic.Aim is to study which variant of permanent AF without intra-heart thrombi is the most unfavorable in appearing of stroke.Methods. We observed 202 patients with permanent AF without intra-heart thrombi and hemodynamically not significant carotid bifurcation atherosclerotic stenosis. We performed echocardiography, 24-hours monitoring of electrocardiography (ECG), ultrasound of brachiocephalic arteries, sphygmography of common carotid arteries, computer tomography of the brain, hemostasiograms, lipid profile, hemoglobin A1c. According to the 24-hours ECG monitoring data, we divided patients into two groups up to the maximum pauses between ventricular complexes in AF: patients with a pause <1,5 seconds (113); ≥1,5 seconds (89). Both groups were on the same standard therapy including novel oral anticoagulants. We observed the patients during 1 year to analyze the verified stroke or transient ischemic attack (TIA).Results. In ultrasound, there was an increase of linear blood flow velocity in the area of carotid stenosis during the spread of the pulse wave after the long pause between ventricular contractions in group 2 up to 2,5 m/sec as in hemodynamically significant stenosis. In 1-year observation, there was the higher stroke in group 2.Conclusion. The appearance of stroke and TIA in AF is higher in patients who have 1,5 seconds and more of maximum duration pauses between ventricular contractions. The reason of cryptogenic stroke can be the atherosclerotic plaque defragmentation with further embolism, caused by additional mechanical impact of increased hemodynamical parameters of pulse wave after long pause between ventricular contractions.
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