Destructive energy impact to the myocard damage: between technological advantages and risk

Background: The aim of the study was to evaluate and compare destruction effect to different heart structures using RF, cryo and laser methodology in animal (pig) model. Methods: Ablation procedure was performed on right and left pulmonary veins area, free wall of right and left atrias, and free wall of ventricles positioning ablation electrode from endocardial side. Ablation electrodes were inserted through an incision in right/left auricle. The effects of ablation were observed visually and using thermography for temperature control. Results: Standard recommended parameters for both of used destruction energies were possible to evoke quick critical scar formation and rupture. Temperature in cardiac surface differs from 34.5 till 70.2 °C, and directly depends from electrode compression level, time of application and energy power. We express dissent from the general view, what destruction in cardiac structures is point like. We observed enough high range of temperature dispersion, especially in ventricles. Conclusions: Usage of thermography enable to estimate peculiarities and borders of destruction site, optimize parameters of ablation, allows us to avoid or minimize undesirable effects, save structures and improve clinical outcomes

Boundary Element Modeling of Acoustic Fields Generated During Ultrasonic Angioplasty

We investigated possibilities of application of boundary element method (BEM) to modelling of acoustic fields generated during ultrasonic angioplasty. It was shown that modelling by means of BEM can be more efficient comparing with traditionally used modelling by means of finite element method (FEM). We also considered test problem of calculation of acoustic field created by ultrasonic waveguide in semi-infinite fluid media and the problem was solved by means of BEM and FEM with comparative analysis of obtained results. Modelling by means of BEM additionally involves application of mirror source method for avoidance of treatment of infinite fluid boundary. On the basis of analysis of the test problem we shown that BEM can be used as efficient tool for modelling of acoustic fields generated during ultrasonic surgical procedures, particularly, during ultrasonic angioplasty. BEM has several advantages in comparison with FEM and can be used as alternative to traditionally used modelling by means of FEM or as supplementary method

Combined effect of low-frequency high-intensity ultrasound and streptokinase on the efficiency of thrombi destruction

Results of numerous experimental studies indicate that low-intensity ultrasound (US) intensifies the drug induced fibrinolysis. However, exits opinion, what high-intensity ultrasound could be not recommending for use in combination with thrombolytic agents due to the transience of exposure of thrombus to ultrasound and relatively low speed of the enzymatic process. We also hypothesise that high-intensity low-frequency US can accelerate the drug induced fibrinolysis. During in vitro studies, we showed that the administration of streptokinase (SK) prevents the formation of particle conglomerates resulting due to destruction of fibrin clots by using low-frequency high-intensity US. In addition, it was established that in conditions of the combined effect of streptokinase and high-intensity US, the process of acoustic-mechanical destruction of thrombus is prevailing, and the fibrinolytic effect of streptokinase is generally witnessed after the termination of US and manifests itself in enzymatic lysis of both resultant particles and residual clot mass. In this study we verified the effect of low-frequency high-intensity ultrasound on the dynamics and efficiency of fibrinolysis induced by streptokinase on various structure thrombi model, characteristic features of the fibrin clot network structure occurring during the combined effect of ultrasound and streptokinase

Low frequency and high intensity ultrasound in vascular surgery: theory, instrumentation and possibilities of clinical application

This paper presents a brief review of applications of ultrasound in modern surgery and results of original studies of the authors in the field of application of low frequency (24-36 kHz) high-intensity (up to 20 W/cm2) ultrasonic vibrations for disruption of thrombi and calcified atherosclerotic plaques in blood vessels. Application of non-rigid wire ultrasonic waveguides with length up to 980 mm and diameter of working tip down to 0.3 mm enables minimally invasive surgical intervention, since a waveguide can be introduced along curved segments of blood vessels through a small incision situated at substantial distance from occlusion. Ultrasonic angioplasty can be successfully applied in combination with administration of thrombolytic drugs. The paper also considers physical mechanisms of thrombus disruption under influence of ultrasonic vibrations, particularly, effects of cavitation and acoustic streaming. We described design of ultrasonic waveguides for endovascular surgery and their manufacturing technology based on plasma-electrolytic etching. Application of finite element method and transfer matrix approach for design and model of wire waveguides is considered. Description of clinical system for ultrasonic angioplasty with automated resonance tuning of a waveguide is also provided. In addition, we report results of clinical application of ultrasonic angioplasty in patients with occlusion of iliofemoral segment

Combined effect of low-frequency high-intensity ultrasound and streptokinase on the efficiency of thrombi destruction

Results of numerous experimental studies indicate that low-intensity ultrasound (US) intensifies the drug induced fibrinolysis. However, exits opinion, what high-intensity ultrasound could be not recommending for use in combination with thrombolytic agents due to the transience of exposure of thrombus to ultrasound and relatively low speed of the enzymatic process. We also hypothesise that high-intensity low-frequency US can accelerate the drug induced fibrinolysis. During in vitro studies, we showed that the administration of streptokinase (SK) prevents the formation of particle conglomerates resulting due to destruction of fibrin clots by using low-frequency high-intensity US. In addition, it was established that in conditions of the combined effect of streptokinase and high-intensity US, the process of acoustic-mechanical destruction of thrombus is prevailing, and the fibrinolytic effect of streptokinase is generally witnessed after the termination of US and manifests itself in enzymatic lysis of both resultant particles and residual clot mass. In this study we verified the effect of low-frequency high-intensity ultrasound on the dynamics and efficiency of fibrinolysis induced by streptokinase on various structure thrombi model, characteristic features of the fibrin clot network structure occurring during the combined effect of ultrasound and streptokinase

Combined effect of low-frequency high-intensity ultrasound and streptokinase on the efficiency of thrombi destruction

Results of numerous experimental studies indicate that low-intensity ultrasound (US) intensifies the drug induced fibrinolysis. However, exits opinion, what high-intensity ultrasound could be not recommending for use in combination with thrombolytic agents due to the transience of exposure of thrombus to ultrasound and relatively low speed of the enzymatic process. We also hypothesise that high-intensity low-frequency US can accelerate the drug induced fibrinolysis. During in vitro studies, we showed that the administration of streptokinase (SK) prevents the formation of particle conglomerates resulting due to destruction of fibrin clots by using low-frequency high-intensity US. In addition, it was established that in conditions of the combined effect of streptokinase and high-intensity US, the process of acoustic-mechanical destruction of thrombus is prevailing, and the fibrinolytic effect of streptokinase is generally witnessed after the termination of US and manifests itself in enzymatic lysis of both resultant particles and residual clot mass. In this study we verified the effect of low-frequency high-intensity ultrasound on the dynamics and efficiency of fibrinolysis induced by streptokinase on various structure thrombi model, characteristic features of the fibrin clot network structure occurring during the combined effect of ultrasound and streptokinase

Low frequency and high intensity ultrasound in vascular surgery: theory, instrumentation and possibilities of clinical application

This paper presents a brief review of applications of ultrasound in modern surgery and results of original studies of the authors in the field of application of low frequency (24-36 kHz) high-intensity (up to 20 W/cm2) ultrasonic vibrations for disruption of thrombi and calcified atherosclerotic plaques in blood vessels. Application of non-rigid wire ultrasonic waveguides with length up to 980 mm and diameter of working tip down to 0.3 mm enables minimally invasive surgical intervention, since a waveguide can be introduced along curved segments of blood vessels through a small incision situated at substantial distance from occlusion. Ultrasonic angioplasty can be successfully applied in combination with administration of thrombolytic drugs. The paper also considers physical mechanisms of thrombus disruption under influence of ultrasonic vibrations, particularly, effects of cavitation and acoustic streaming. We described design of ultrasonic waveguides for endovascular surgery and their manufacturing technology based on plasma-electrolytic etching. Application of finite element method and transfer matrix approach for design and model of wire waveguides is considered. Description of clinical system for ultrasonic angioplasty with automated resonance tuning of a waveguide is also provided. In addition, we report results of clinical application of ultrasonic angioplasty in patients with occlusion of iliofemoral segment