Abstract: A reference voltage buffer circuit (20) includes first and second transistors (M1, M2) and first and second resistors (R1, R2) connected in series between positive and negative power supply voltages and providing a positive reference voltage (Vrp) and a negative reference voltage (Vrn) at the first current handling terminals of the first and second transistors, respectively. A first control voltage (Vg1) for driving the first transistor is generated by a first feedback loop and using a positive boosted voltage. A second control voltage (Vg2) for driving the second transistor is generated by a second feedback loop and using a negative boosted voltage. The first and second feedback loops establish the first and second control voltages while the positive and negative boosted voltages ensure sufficient drives are provided to the first and second transistors. The reference voltage buffer is capable of fast settling while maintaining a wide reference voltage range.

Abstract: An adjustable surgical clamp including one or more ablation elements creates a circular lesion in a first operating mode and a linear lesion in a second operating mode. A “box” lesion surrounding all four pulmonary veins may be formed by using the clamp to create two complimentary C-shaped lesions about pairs of the veins. A thermochromic liquid crystal strip that changes color at a tissue-ablating threshold temperature may be mounted on the surgical clamp to monitor temperature of the ablated tissue. Two microwave antennae may be positioned on the jaws of the clamp relative to each other to produce a combined substantially uniform field of tissue-ablating energy between the jaws.

Abstract: A system and method for positioning a medical instrument at a desired biological target tissue site is provided. The system includes an elongated sheath having a deflectable distal end configured to deflect or otherwise position at least a portion of a medical instrument during a surgical procedure allowing for the placement of the deflected portion adjacent or proximate to a predetermined target tissue surface. The positioning system may be incorporated into the medical instrument. The medical instrument may be an ablation system.

Abstract: A radionuclide emission tomography camera for sensing gamma ray emissions from a source within the field of view, including: a fixed position-sensitive detector, responsive to the gamma ray emissions and surrounding the field of view, for detecting the contact position and the trajectory from which a gamma ray emission originates; a rotatable collimator disposed between the fixed position-sensitive detector and the field of view and including at least one array of collimator elements for restricting and collimating the gamma ray emissions; and means for rotating the collimator relative to the fixed position-sensitive detector for exposing different sections of the position-sensitive detector to the gamma ray emissions in order to view the source from different angles.

Abstract: A transaxial radionuclide emission camera apparatus and method for image reconstruction using data collected by the apparatus are disclosed. A significant feature of the camera apparatus is a detector means which is arcuately shaped. For example, a suitable detector means can be formed from an optically continuous, arcuately shaped strip of scintillation material and an array of photodetectors optically coupled to said scintillation material. These photodetectors sense light emitted by the scintillation material in response to absorbed radiation. Collimating means which converge to the center of an arc defined by the detector means are another significant feature. The transaxial camera apparatus and the method disclosed are useful in reconstructing images of the distribution of a source of penetrating radiation contained within a body.