Development of a Shock-Wave Catheter Ablation System for Ventricular Tachyarrhythmias: Validation Study in Pigs In Vivo.

Background Although radiofrequency catheter ablation is the current state-of-the-art treatment for ventricular tachyarrhythmias, it has limited success for several reasons, including insufficient lesion depth, prolonged inflammation with subsequent recurrence, and thromboembolisms due to myoendocardial thermal injury. Because shock waves can be applied to deep lesions without heat, we have been developing a shock-wave catheter ablation ( SWCA ) system to overcome these fundamental limitations of radiofrequency catheter ablation. In this study, we evaluated the efficacy and safety of our SWCA system for clinical application to treat ventricular tachyarrhythmia.

Development of a novel shock wave catheter ablation system-A validation study in pigs in vivo.

Aims: Although the radiofrequency catheter ablation (RFCA) is widely used for the treatment of tachyarrhythmias, it has three fundamental weaknesses as a thermal ablation system, including a limited lesion depth, myoendocardial injury linking to thromboembolism, and prolonged inflammation followed by subsequent recurrences. In order to overcome these limitations, we have been developing a shock wave (SW) catheter ablation (SWCA) system as a novel non-thermal therapy. In the present study, we validated our new SWCA system with increased SW intensity.

Development of a novel shock wave catheter ablation system--the first feasibility study in pigs.

Introduction: Radio-frequency catheter ablation (RFCA) using Joule heat has two fundamental weaknesses: the limited depth of treatment and the risk of thrombus formation. In contrast, focused shock wave (SW) therapy could damage tissues at arbitrary depths without heat generation. Thus, we aimed to develop a SW catheter ablation (SWCA) system that could compensate for the weaknesses of RFCA therapy.

Experimental application of pulsed laser-induced water jet for endoscopic submucosal dissection: mechanical investigation and preliminary experiment in swine.

Background And Aim: A current drawback of endoscopic submucosal dissection (ESD) for early-stage gastrointestinal tumors is the lack of instruments that can safely assist with this procedure. We have developed a pulsed jet device that can be incorporated into a gastrointestinal endoscope. Here, we investigated the mechanical profile of the pulsed jet device and demonstrated the usefulness of this instrument in esophageal ESD in swine.

Laser plasma jet driven microparticles for DNA/drug delivery.

This paper describes a microparticle delivery device that generates a plasma jet through laser ablation of a thin metal foil and uses the jet to accomplish particle delivery into soft living targets for transferring biological agents. Pure gold microparticles of 1 µm size were coated with a plasmid DNA, pIG121Hm, and were deposited as a thin layer on one surface of an aluminum foil. The laser (Nd:YAG, 1064 nm wavelength) ablation of the foil generated a plasma jet that carried the DNA coated particles into the living onion cells.

Characteristics of an actuator-driven pulsed water jet generator to dissecting soft tissue.

This paper reports characteristics of an actuator-driven pulsed water jet generator applied, in particular, to dissect soft tissues. Results of experiments, by making use of high speed recording of optical visualization and varying nozzle diameter, actuator time interval, and their effects on dissection performance are presented. Jet penetration characteristics are compared with continuous water jet and hence potential assessment of pulsed water jets to clinical applications is performed.

Mechanisms of primary blast-induced traumatic brain injury: insights from shock-wave research.

Traumatic brain injury caused by explosive or blast events is traditionally divided into four phases: primary, secondary, tertiary, and quaternary blast injury. These phases of blast-induced traumatic brain injury (bTBI) are biomechanically distinct and can be modeled in both in vivo and in vitro systems. The primary bTBI injury phase represents the response of brain tissue to the initial blast wave.

Pulsed laser-induced liquid jet for skull base tumor removal with vascular preservation through the transsphenoidal approach: a clinical investigation.

Background: The transsphenoidal approach has recently been used to treat complex lesions beyond the sella turcica, but the difficulties of dealing with small vessels, deep and narrow space, and working angle may limit the procedures. To overcome these problems, we have developed a pulsed laser-induced liquid jet (LILJ) system to dissect tumor tissue with preservation of fine blood vessels within deep and narrow working spaces and evaluated its utility and safety.

Methods: The LILJ system was applied to 14 consecutive patients with uncharacteristically complex skull base tumor treated through the extended transsphenoidal approach.

[Clinical application of pulsed laser-induced liquid jet: preliminary report in glioma surgery].

Purpose: Both maximum resection of tumor and preservation of fine vessels are conflicting aims, but important factors to improve outcome in glioma surgery. Water jet dissection has been reported to dissect tissue while ensuring preservation of fine vessels. However, it was difficult to apply conventional water jet device in microsurgery due to the use of high pressure and continuous water a flow.

Shock wave-induced brain injury in rat: novel traumatic brain injury animal model.

Background: In blast wave injury and high-energy traumatic brain injury, shock waves (SW) play an important role along with cavitation phenomena. However, due to lack of reliable and reproducible technical approaches, extensive study of this type of injury has not yet been reported. The present study aims to develop reliable SW-induced brain injury model by focusing micro-explosion generated SW in the rat brain.

Pressure-dependent effect of shock waves on rat brain: induction of neuronal apoptosis mediated by a caspase-dependent pathway.

Object: Shock waves have been experimentally applied to various neurosurgical treatments including fragmentation of cerebral emboli, perforation of cyst walls or tissue, and delivery of drugs into cells. Nevertheless, the application of shock waves to clinical neurosurgery remains challenging because the threshold for shock wave-induced brain injury has not been determined. The authors investigated the pressure-dependent effect of shock waves on histological changes of rat brain, focusing especially on apoptosis.

[Intraoperative brain surface blood flow monitoring using IRIS V thermographic imaging system in patients with Moyamoya disease].

Surgical revascularization for moyamoya disease prevents cerebral ischemic attacks by improving CBF. But little is known about the changes of intraoperative cerebral hemodynamics and its effect on postoperative neurological status including symptomatic cerebral hyperperfusion. To address this issue, we applied a novel infrared camera system (IRIS-V thermographic system) for real-time, visual monitoring of surface CBF during surgery in patients with moyamoya disease.

Shock wave induced cytoskeletal and morphological deformations in a human renal carcinoma cell line.

Effects of shock waves on the morphology and cytoskeleton of a human renal carcinoma cell line (ACHN) were investigated in vitro. ACHN monolayer cultured on a cover slide glass was treated with 10 shots of focused underwater shock waves, with 16 MPa peak pressure at the focal area of a piezoceramic shock wave generator. After exposure to the shock wave, based on the severity of morphological deformations of the treated cells, the monolayer was divided into three morphological areas; focal, marginal and intact.

A proposed parent vessel geometry-based categorization of saccular intracranial aneurysms: computational flow dynamics analysis of the risk factors for lesion rupture.

Object: The authors created a simple, broadly applicable classification of saccular intracranial aneurysms into three categories: sidewall (SW), sidewall with branching vessel (SWBV), and endwall (EW) according to the angiographically documented patterns of their parent arteries. Using computational flow dynamics analysis (CFDA) of simple models representing the three aneurysm categories, the authors analyzed geometry-related risk factors such as neck width, parent artery curvature, and angulation of the branching vessels.

Methods: The authors performed CFDAs of 68 aneurysmal geometric formations documented on angiograms that had been obtained in patients with 45 ruptured and 23 unruptured lesions.

Submicrosecond temperature measurement in liquid water with laser-induced thermal acoustics.

Using laser-induced thermal acoustics, we demonstrate nonintrusive and remote sound-speed and temperature measurements in liquid water. Unsteady thermal gradients in the water sample produce fast, random laser beam misalignments, which are the primary source of uncertainty in these measurements. For water temperatures over the range 10 degrees C to 45 degrees C, the precision of a single 300-ns-duration measurement varies from +/-1 to +/-16.

Compact monochromatic flash x-ray generator utilizing a disk-cathode molybdenum tube.

The high-voltage condensers in a polarity-inversion two-stage Marx surge generator are charged from -50 to -70 kV by a power supply, and the electric charges in the condensers are discharged to an x-ray tube after closing gap switches in the surge generator with a trigger device. The x-ray tube is a demountable diode, and the turbo molecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Clean molybdenum Kalpha lines are produced using a 20 microm-thick zirconium filter, since the tube utilizes a disk cathode and a rod target, and bremsstrahlung rays are not emitted in the opposite direction to that of electron acceleration.

Demonstration of enhanced K-edge angiography using a cerium target x-ray generator.

The cerium target x-ray generator is useful in order to perform enhanced K-edge angiography using a cone beam because K-series characteristic x rays from the cerium target are absorbed effectively by iodine-based contrast mediums. The x-ray generator consists of a main controller, a unit with a Cockcroft-Walton circuit and a fixed anode x-ray tube, and a personal computer. The tube is a glass-enclosed diode with a cerium target and a 0.

Computational replicas: anatomic reconstructions of cerebral vessels as volume numerical grids at three-dimensional angiography.

Background And Purpose: We present a relatively simple approach that physicians can use to reconstruct cerebral vessels as 3D numerical grids or computational replicas. The method accurately duplicates their geometry to provide computer simulations of their blood flow.

Methods: Initial images were obtained by using any medical imaging technique, such as MR angiography, CT angiography, or 3D digital subtraction angiography.

Monochromatic polycapillary imaging utilizing a computed radiography system.

A fundamental study on quasi-parallel radiography using a polycapillary plate and a copper-target x-ray tube is described. In the experiments, the tube voltage was regulated from 12 to 22 kV, and the tube current was regulated within 3.0 mA by the filament temperature.

Pulsed holmium:yttrium-aluminum-garnet laser-induced liquid jet as a novel dissection device in neuroendoscopic surgery.

Object: A pressure-driven continuous jet of water has been reported to be a feasible tool for neuroendoscopic dissection owing to its superiority at selective tissue dissection in the absence of thermal effects. With respect to a safe, accurate dissection, however, continuous water flow may not be suitable for intraventricular use. The authors performed experiments aimed at solving problems associated with continuous flow by using a pulsed holmium:yttrium-aluminum-garnet (Ho:YAG) laser-induced liquid jet (LILJ).

Experimental application of pulsed Ho:YAG laser-induced liquid jet as a novel rigid neuroendoscopic dissection device.

Background And Objectives: Although water jet technology has been considered as a feasible neuroendoscopic dissection methodology because of its ability to perform selective tissue dissection without thermal damage, problems associated with continuous use of water and the ensuing fountain-effect-with catapulting of the tissue-could make water jets unsuitable for endoscopic use, in terms of safety and ease of handling. Therefore, the authors experimented with minimization of water usage during the application of a pulsed holmium:yttrium-aluminum-garnet (Ho:YAG) laser-induced liquid jet (LILJ), while assuring the dissection quality and the controllability of a conventional water jet dissection device. We have developed the LILJ generator for use as a rigid neuroendoscope, discerned its mechanical behavior, and evaluated its dissection ability using the cadaveric rabbit ventricular wall.

Ca2+ binding sites in calmodulin and troponin C alter interhelical angle movements.

Molecular dynamics analyses were performed to examine conformational changes in the C-domain of calmodulin and the N-domain of troponin C induced by binding of Ca(2+) ions. Analyses of conformational changes in calmodulin and troponin C indicated that the shortening of the distance between Ca(2+) ions and Ca(2+) binding sites of helices caused widening of the distance between Ca(2+) binding sites of helices on opposite sides, while the hydrophobic side chains in the center of helices hardly moved due to their steric hindrance. This conformational change acts as the clothespin mechanism.

Computational simulation of therapeutic parent artery occlusion to treat giant vertebrobasilar aneurysm.

We applied computational fluid dynamics (CFD) analysis to assess 3D digital subtraction angiography findings in a patient with a giant vertebrobasilar aneurysm to simulate and compare the consequences of left and right vertebral artery occlusion. The balloon occlusion test suggested that occlusion of the right vertebral artery is the better way to treat this patient's aneurysm from the point of view of aneurysmal thrombosis and isolation from the circulation. The computer simulation supported this conclusion, at the same time indicating that from the point of view of pressure distribution on the wall of the aneurysm, the right vertebral occlusion may be also accompanied by an undesirable effect.

Irradiation of intense characteristic x-rays from weakly ionized linear molybdenum plasma.

In the plasma flash x-ray generator, a high-voltage main condenser of approximately 200 nF is charged up to 55 kV by a power supply, and electric charges in the condenser are discharged to an x-ray tube after triggering the cathode electrode. The flash x-rays are then produced. The x-ray tube is a demountable triode that is connected to a turbo molecular pump with a pressure of approximately 1 mPa.