Abstract: An apparatus for delivering energy to a biological site includes a catheter having an ablation electrode and a plurality of backplates distributed at various locations proximal the biological site. The backplates are coupled to a switching device for selecting which backplate to utilize as a return electrode to complete the circuit with the ablation electrode in order to obtain deeper, larger lesions for a given amount of energy. The backplate selection is made by determining which return electrode most closely places the biological site between the ablation electrode and the backplate. Backplate selection may be made automatically based on impedance measurements or conduction time measurements. Alternatively, the backplate selection can be made manually.

Abstract: Information indicative of the flow rate of fluid through a biological organ is provided to a processor. Using this information the processor assesses whether the fluid-flow rate is high or low and controls a generator such that the generator provides energy to an electrode positioned within the organ to effect tissue ablation. Energy of a first level is provided during periods of high fluid-flow and energy of a second level, less than the first level, during periods of low fluid-flow. The flow rate information may be provided by an electrocardiograph (ECG) device or a flow sensor. A temperature sensor provides temperature signals to the processor indicative of the electrode temperature. The processor further controls the generator based on the electrode temperature to maintain the temperature at or near a target temperature and below a maximum threshold temperature.

Abstract: A method of presenting information for evaluating the condition of chronically impaired cardiac patients based on long-term assessment of activity trends, using a memoried implanted cardiac rhythm management device having a plurality of programmable parameters and one or more sensors for sensing one or more parameters related to an activity level of the patient. The method includes acquiring sensor signal data indicative of the activity level of the patient, accumulating sensor signal data in memory and using the accumulated sensor signal data to determine the activity level of the patient during a predetermined period of time, recording the activity level during a plurality of sequential time periods, adding contemporary annotation information to the activity data and producing a data record of the activity level with the annotation information during sequential time periods sufficient to indicate trends in a patient's activity level.