Abstract: A catheter comprises an elongated catheter body, a control handle, and a hollow tip electrode having a radially-symmetrical shell defining a cavity surrounding a center inner location from which light is emitted to pass through a plurality of openings formed in the shell for interaction with tissue and/or fluid, such as blood, outside of and in contact with the shell. Light interacting with tissue is reflected back into the cavity for collection whereas light interacting with fluid, such as blood, is absorbed. By analyzing the light collected in the cavity, a determination is made as to a ratio of light reflected by tissue versus light absorbed by fluid for indicating the amount of contact between the tip electrode and tissue. Alternatively, fluorescence may similarly be employed (light is emitted at one wavelength and detected at one or more different wavelengths) since tissue and blood have different fluorescence properties at various wavelengths.

Abstract: A catheter adapted for use in the pericardial sac to sense temperature of an ablation site and surrounding heart tissue within one of the heart's ventricles or atria via proximity with the epicardium in the pericardial sac, includes a catheter body and a temperature sensing array adapted for placement on and contact with the epicardium. The temperature sensing array may comprise a 2-D body, with a surface adapted to contact an area on the epicardial tissue or in pericardial space. The array may also comprise at least one finger member, each having at least one temperature sensing location. The array may further comprise an elongated body having a generally circular configuration, a distal portion of which is movable to a spirally inward position.

Abstract: A catheter comprises an elongated catheter body, a control handle, and a hollow tip electrode having a radially-symmetrical shell defining a cavity surrounding a center inner location from which light is emitted to pass through a plurality of openings formed in the shell for interaction with tissue and/or fluid, such as blood, outside of and in contact with the shell. Light interacting with tissue is reflected back into the cavity for collection whereas light interacting with fluid, such as blood, is absorbed. By analyzing the light collected in the cavity, a determination is made as to a ratio of light reflected by tissue versus light absorbed by fluid for indicating the amount of contact between the tip electrode and tissue. Alternatively, fluorescence may similarly be employed (light is emitted at one wavelength and detected at one or more different wavelengths) since tissue and blood have different fluorescence properties at various wavelengths.

Abstract: A catheter comprises an elongated catheter body, a control handle, and a hollow tip electrode having a radially-symmetrical shell defining a cavity surrounding a center inner location from which light is emitted to pass through a plurality of openings formed in the shell for interaction with tissue and/or fluid, such as blood, outside of and in contact with the shell. Light interacting with tissue is reflected back into the cavity for collection whereas light interacting with fluid, such as blood, is absorbed. By analyzing the light collected in the cavity, a determination is made as to a ratio of light reflected by tissue versus light absorbed by fluid for indicating the amount of contact between the tip electrode and tissue. Alternatively, fluorescence may similarly be employed (light is emitted at one wavelength and detected at one or more different wavelengths) since tissue and blood have different fluorescence properties at various wavelengths.

Abstract: A catheter comprises an elongated catheter body, a control handle, and a hollow tip electrode having a radially-symmetrical shell defining a cavity surrounding a center inner location from which light is emitted to pass through a plurality of openings formed in the shell for interaction with tissue and/or fluid, such as blood, outside of and in contact with the shell. Light interacting with tissue is reflected back into the cavity for collection whereas light interacting with fluid, such as blood, is absorbed. By analyzing the light collected in the cavity, a determination is made as to a ratio of light reflected by tissue versus light absorbed by fluid for indicating the amount of contact between the tip electrode and tissue. Alternatively, fluorescence may similarly be employed (light is emitted at one wavelength and detected at one or more different wavelengths) since tissue and blood have different fluorescence properties at various wavelengths.

Abstract: A catheter adapted for use in the pericardial sac to sense temperature of an ablation site and surrounding heart tissue within one of the heart's ventricles or atria via proximity with the epicardium in the pericardial sac, includes a catheter body and a temperature sensing array adapted for placement on and contact with the epicardium. The temperature sensing array may comprise a 2-D body, with a surface adapted to contact an area on the epicardial tissue or in pericardial space. The array may also comprise at least one finger member, each having at least one temperature sensing location. The array may further comprise an elongated body having a generally circular configuration, a distal portion of which is movable to a spirally inward position.

Abstract: A homodyne radar apparatus and method for performing radar cross-section surement by maintaining the linearity and compensating for frequency drift of an FM chirp waveform produced by a YIG tuned oscillator. A digital computer uses a predetermined data look-up table of each YIG oscillator frequency characteristic in conjunction with a digital to analog converter to provide a compensating sweep signal to linearize the frequency output of the oscillator. The computer uses an analog to digital converter in conjunction with a reference circuit output to compare the actual YIG signal nulls resulting from the reference circuit to the nulls in a signal produced by a lab standard oscillator in the reference circuit to adjust start sample delay of the ADC and to correct any frequency drift evidenced by the difference in the null of the signal.