Abstract: Method and apparatus to modify a fluid by passing a compound through a selectively permeable membrane is provided. In one embodiment a fluid moving through a vessel is modified prior to its ejection from the vessel. This may be accomplished by urging the fluid into a mixing chamber wherein the mixing chamber is in fluid communication with an exit orifice and a passageway. This passageway may be in communication with a second chamber through a selectively permeable membrane. The fluid may then be altered by passing a compound between the mixing chamber and the second chamber through the passageway and the selectively permeable membrane. A device for modifying a fluid moving through a vessel may contain a first lumen, a second lumen, an exit orifice, and a mixing chamber in communication with the first lumen and the exit orifice.

Abstract: A method and apparatus for limiting the application of ablation energy to viable myocardial tissue. An ablation energy generator produces a test signal that is applied to the heart muscle. The response of the heart muscle to the test signal is determined and used to analyze the viability of the heart tissue. If the heart muscle is viable, a higher powered ablation pulse may be delivered. If the tissue is not viable, no ablation energy is delivered. In one embodiment of the invention, the test signal is a low voltage, high frequency signal and the impedance of the tissue in response to the test signal is detected to determine tissue viability.

Abstract: An RF ablation system includes a catheter and an RF electrode that delivers RF electrical energy to the site of an occlusion. The system includes a mechanism for minimizing the likelihood that RF electrical energy will be applied directly to the vessel wall. In one embodiment of the invention, the catheter includes a number of tissue expanding jaws to engage a vessel wall and push the vessel wall away from the electrode to shield vessel walls from the electrode. In yet another embodiment of the invention, the electrode has a spiraled distal end with a radius that is larger than the radius of the catheter, such that the electrode engages the vessel wall and pushes the wall away from a conducting portion of the electrode. The portion of the electrode that engages the vessel wall is preferably coated with an insulating material to prevent delivery of RF electrical energy directly to the vessel wall.

Abstract: An atherectomy device that may reduce the risk of damage to a vessel wall. One rotatable atherectomy burr has a recessed material removal portion lying between less abrasive proximal and distal shoulders. The shoulders can have a straight, rounded or elliptical taper. The shoulders can perform a cam action when the burr is canted is a vessel, as when passing the burr and guide wire through a tortuous, stenosed vessel path. The shoulders act to align the burr with the path through the vessel, presenting the less abrasive shoulders to the vessel wall while presenting the abrasive portion to a stenosis.

Abstract: An atherectomy device that may reduce the risk of damage to a vessel wall. One rotatable atherectomy burr has a recessed material removal portion lying between less abrasive proximal and distal shoulders. The shoulders can have a straight, rounded or elliptical taper. The shoulders can perform a cam action when the burr is canted is a vessel, as when passing the burr and guide wire through a tortuous, stenosed vessel path. The shoulders act to align the burr with the path through the vessel, presenting the less abrasive shoulders to the vessel wall while presenting the abrasive portion to a stenosis.