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Background: A new cooling method is proposed for preventing electrode-tissue overheating during cardiac catheter ablation using a vibrating catheter. Previous work has shown that vibration that results from increased flow velocity around the catheter can have a cooling effect on the electrode.Objective: Contact force has been shown to be an important factor that affects cooling and lesion formation, because contact force determines the ratio of power delivery between blood and tissue. In this study, the effect of contact force on electrode cooling and tissue heating was investigated during the operation of an electrode cooled by vibration.Methods: Using PVA-H or myocardium ablation tissue models under conditions of no flow, electrode and tissue temperatures and lesion sizes were measured at various vibrational frequencies and contact force conditions.Results: The experiments showed that the catheter vibration still decreases the electrode temperature over a contact force range of 2-30 gf. The lesion size was increased with increasing contact force at each vibrational frequency.Conclusions: Increasing contact force can increase lesion size with cooling by vibration remaining effective. [ABSTRACT FROM AUTHOR]

Objective: In this paper, we investigated the parameters with effective traceability to assess the mechanical properties of interventional devices.Methods: In our evaluation system, a box-shaped poly (vinyl alcohol) hydrogel (PVA-H) and silicone were prepared with realistic geometry, and the measurement and evaluation of traceability were carried out on devices using load hand force. The phantom models had a total of five curve pathways to reach the aneurysm sac.Results: Traceability depends on the performance of the interventional devices in order to pass through the curved part of the model simulation track. The traceability of the guide wire was found to be much better than that of the balloon and stent loading catheter, as it reached the aneurysm sac in both phantom models.Conclusions: Observation using the video record is another advantage of our system, because the high transparency of the materials with silicone and PVA-H can allow visualization of the inside of an artery. [ABSTRACT FROM AUTHOR]

In this paper, we investigated several parameters with effect on the compressive force to assess the mechanical properties of interventional device. We find several parameters are highly influential and others are not. In our evaluation system, we prepared a box-shaped PVA-H and silicone with realistic geometry and carried out the measurement and evaluation of the pushability by using load cell machine. The parameters of velocity, position of device in the system do not affect the compressive force, whereas the length of catheter from the tip to fixed point is one of the most influential parameters for the force. Several behaviors such as passing through the curve or slip and stop can be observed and defined using this system. The balance of the bending force and the pushing force may make the tip with behavior of slip and stop or passing thorough the curve. The investigation of the evaluation system confirmed that high reproducibility with short error bar is indicated. The observation with movie record is also an advantage of our system because the high transparency of materials with silicone and PVA-H can check the inside of artery. [ABSTRACT FROM AUTHOR]

BACKGROUND: Plaques in blood vessels exhibit a wide range of stiffness depending on disease conditions: stiffness is an important factor in plaque behavior. The geometrical change in plaque based on its behavior can affect blood flow patterns. Thus, it is important to study both blood flow and deformation of plaques and blood vessels.OBJECTIVE: This study aims to identify the differences in flow conditions between in vitro models to discuss experimental materials for arterial wall and flow observation.METHODS: In order to observe the blood flow pattern and plaque deformation simultaneously, a PVA-H stenosis model was used. In addition, a silicone model was also used as a rigid-like model for comparison with the PVA-H model. PIV was employed to measure the flow velocity distribution and determine the flow levels in the models.RESULTS: PVA-H model exhibits expansion with an increase in upstream pressure and silicone model maintains the diameter. The expansion depends on their mechanical properties and influences flow conditions such as velocity changes and RAP in the parent artery. The balance between the expansion and change in flow conditions determines the final geometries of PVA-H model and flow pattern. CONCLUSIONS: The results suggest that the stiffness measurement for blood vessels and plaques such as ultrasound measurements would be important for accurate treatments. [ABSTRACT FROM AUTHOR]

In this paper, we investigated several parameters with effect on the compressive force to assess the mechanical properties of interventional device. We find several parameters are highly influential and others are not. In our evaluation system, we prepared a box-shaped PVA-H and silicone with realistic geometry and carried out the measurement and evaluation of the pushability by using load cell machine. The parameters of velocity, position of device in the system do not affect the compressive force, whereas the length of catheter from the tip to fixed point is one of the most influential parameters for the force. Several behaviors such as passing through the curve or slip and stop can be observed and defined using this system. The balance of the bending force and the pushing force may make the tip with behavior of slip and stop or passing thorough the curve. The investigation of the evaluation system confirmed that high reproducibility with short error bar is indicated. The observation with movie record is also an advantage of our system because the high transparency of materials with silicone and PVA-H can check the inside of artery. [ABSTRACT FROM AUTHOR]