Abstract: An apparatus for mapping and/or ablating tissue includes a braided conductive member that that may be inverted to provide a ring-shaped surface. When a distal tip of the braided conductive member is retracted within the braided conductive member, the lack of a protrusion allows the ring-shaped surface to contact a tissue wall such as a cardiac wall. In an alternative configuration, the braided conductive member may be configured with the distal portion forming a proboscis that can be used to stably position the braided conductive member relative to a blood vessel, such as a ventricular outflow tract. The braided conductive member has a plurality of electronically active sites that may be accessed individually for stable mapping over a broad area for stable mapping or ablation to form broad and deep lesions.

Abstract: A method for making colloidal nanocrystals includes the following steps: dissolving a nanocrystal powder in an organic solvent, and achieving a solution A of a concentration of 1-30 mg/ml; dissolving a surfactant in water, and achieving a solution B of a concentration of 0.002-0.05 mmol/ml; mixing the solution A and the solution B in a volume ratio of 1: (5-30), and achieving a mixture; stirring and emulsifying the mixture, until an emulsion C is achieved; removing the organic solvent from the emulsion C, and achieving a deposit; then washing the deposit with deionized water, and achieving colloidal nanocrystals. The present method for making colloidal nanocrystals is economical and timesaving, and has a low toxicity associated therewith. Thus, the method is suitable for industrial mass production. The colloidal nanocrystals made by the present method have a readily controllable size, a narrow size distribution, and good configuration.

Abstract: A method for making the metal oxide includes the following steps: mixing a metal nitrate with a solvent of octadecyl amine, and achieving a mixture; agitating and reacting the mixture at a reaction temperature for a reaction period; cooling the mixture to a cooling temperature, and achieving a deposit; and washing the deposit with an organic solvent, drying the deposit at a drying temperature and achieving a metal oxide nanocrystal. The present method for making a metal oxide nanocrystal is economical and timesaving, and has a low toxicity associated therewith. Thus, the method is suitable for industrial mass production.

Abstract: An electrophysiology catheter and method of use for mapping and ablation procedures. The catheter includes a braided conductive member at its distal end that can be radially expanded. The catheter can be used in endocardial and epicardial mapping and ablation procedures.

Abstract: The patterns of contraction and relaxation of the heart before and during left ventricular or biventricular pacing are analyzed and displayed in real time mode to assist physicians to screen patients for cardiac resynchronization therapy, to set the optimal AN or right ventricle to left ventricle interval delay, and to select the site(s) of pacing that result in optimal cardiac performance. The system includes an accelerometer sensor (40); a programmable pace maker (35, 41), a computer data analysis module (32), and may also include a 2D and 3D visual graphic display of analytic results (43, 44), i.e. a Ventricular Contraction Map. A feedback network (32) provides direction for optimal pacing leads placement.

Abstract: The patterns of contraction and relaxation of the heart before and during left ventricular or biventricular pacing are analyzed and displayed in real time mode to assist physicians to screen patients for cardiac resynchronization therapy, to set the optimal A-V or right ventricle to left ventricle interval delay, and to select the site(s) of pacing that result in optimal cardiac performance. The system includes an accelerometer sensor; a programmable pace maker, a computer data analysis module, and may also include a 2D and 3D visual graphic display of analytic results, i.e. a Ventricular Contraction Map. A feedback network provides direction for optimal pacing leads placement.

Abstract: An electrophysiology catheter and method of use for mapping and ablation procedures. The catheter includes a braided conductive member at its distal end that can be radially expanded. The catheter can be used in endocardial and epicardial mapping and ablation procedures.

Abstract: A self-cooling electrode for use with an ablation catheter has greater surface area that allows electrode to dissipate heat to the blood pool more effectively and increased thermal mass, and, therefor greater heating capacity/thermal conductivity for improved heat transfer between the electrode and tissue for more effective tissue heating. The electrode design allows increased power to be delivered with minimized risk of overheating or coagulation at the tissue-electrode interface. The increased thermal mass and thermal conductivity of the electrode design are achieved with a substantially solid electrode body with thick walls. Cooling and increased heat exchange are achieved with an alternating pattern of channels and projections that collectively define a plurality of edges either parallel or perpendicular to the electrode axis.

Abstract: A self-cooling electrode for use with an ablation catheter has greater surface area that allows electrode to dissipate heat to the blood pool more effectively and increased thermal mass, and, therefor greater heating capacity/thermal conductivity for improved heat transfer between the electrode and tissue for more effective tissue heating. The electrode design allows increased power to be delivered with minimized risk of overheating or coagulation at the tissue-electrode interface. The increased thermal mass and thermal conductivity of the electrode design are achieved with a substantially solid electrode body with thick walls. Cooling and increased heat exchange are achieved with an alternating pattern of channels and projections that collectively define a plurality of edges either parallel or perpendicular to the electrode axis.

Abstract: An electrophysiology catheter and method of use for mapping and ablation procedures. The catheter includes a braided conductive member at its distal end that can be radially expanded. The catheter can be used in endocardial and epicardial mapping and ablation procedures.

Abstract: Impedance and capacitance-related parameters are monitored in the electrical circuit of a tissue-ablation apparatus wherein RF electrical power is administered at predetermined frequencies. Tissue temperature has been found to correlate well with low-frequency impedance, or with the resistive component of impedance at any frequency. Therefore, one or both of these parameters are calculated and tracked during the ablation procedure to estimate tissue temperature. Similarly, tissue lesion formation has been found to correlate well with changes in the capacitive component of tissue impedance. Thus, this parameter can be used to track tissue lesion formation during the ablation procedure. The ratio of tissue-to-blood interface with the ablation electrode is estimated by measuring impedance at a very low frequency and a very high frequency. The difference between these two values divided by the high-frequency value is taken to be a measure of such ratio.

Abstract: During an ablation procedure in a chamber of the heart RF energy is used to form a myocardial lesion for treatment of some arrhythmias such as sustained supraventricular tachycardia and accessory pathways. A galvanic cell formed by a metallic electrode having a first work function at the ablation site, a second metallic electrode having a second work function located remote from the ablation site and the intervening tissue serving as an electrolyte, produces an output current signal reflective of the formation of a lesion at the ablation site and is used to control the RF energy applied. A curve depicting the output current signal has a maximum value at the point a burn or lesion formation and thereafter decreases in value. A short duration inflection or bump of the curve occurs prior to charring and carbonization of the lesion.