Abstract: A mapping and ablating catheter having a short distal tip electrode comprising a bio-compatible outer surface and a thermal dissipating mass for dissipating heat received by the electrode. The outer surface may be formed by plating a thin layer of gold or platinum on the dissipating mass, or the entire electrode may be formed of a homogenous material such as a gold alloy that is bio-compatible thereby forming the outer surface with the mass itself. An alloy having a thermal conductivity greater than pure platinum is used so that the ablation procedure can be completed before exceeding the temperature limits. In one case, the entire electrode was formed of a 88% gold 12% nickel alloy. The electrical feed to the electrode is oversized to also dissipate heat received by the electrode. The electrode is no greater than five mm in length yet produces an ablation volume equal to or greater than longer electrodes. One or more band electrodes may also include thermal dissipating masses.

Abstract: A pacing lead of the type having a hollow lead body with a conductor linking the electrode at one end with the connector at the other end has a guide wire or stylet either connected to a mechanical vibrator or carrying an ultrasonic transducer in order to cause the guidewire to move within the body to facilitate the display of the catheter position on external ultrasonic monitoring equipment.

Abstract: An implantable medical lead for use with an implantable cardioverter defibrillator, a method of manufacture and a system employing the lead and cardioverter/defibrillator in combination. The lead is provided with an elongated insulative lead body carrying a cardioversion/defibrillation electrode, which includes a first portion displaying essentially equal attenuation of positive and negative voltage pulses and a second portion displaying differential attenuation of positive and negative voltage pulses. The cardioveter/defibrillator provides a biphasic pulse in which a higher amplitude phase of the pulse is differentially attenuated by the electrode. The electrode is fabricated in whole or in part of a valve metal such as tantalum, anodized and annealed to provide a thick, durable oxide coating.

Abstract: There is provided a system and method for determining the existence of metal ion oxidation degradation in an implanted pacing lead. A micro-vibration driver, preferably operating at a sonic frequency matched to an ultrasound detector, is used to vibrate the proximal end of a stylet that has been inserted into the lumen of a bipolar lead. The shaking of the stylet causes flexural waves to be propagated along the stylet, which in turn flex the lead inner conductor and the insulation between the inner and outer conductor. If metal ion oxidation is present in the insulation, the shaking causes generation of a noise signal which is detectable across the conductors along with the electrogram. The presence of such a noise signal is correlated with the output of the driver, i.e., with the vibration of the lead, to indicate when MIO degradation is present. An ultrasound imaging detector can be used to determine the location of the MIO degradation along the length of the lead.

Abstract: An RF ablation catheter of the type comprising a flexible elongate catheter body having at least one lumen therethrough and having a proximal handle end and a distal end section adapted to be introduced into a heart chamber, at least one electrical conductor extending from the handle to the distal tip section within the at least one lumen for conduction RF energy, and a distal tip electrode coupled to the distal end section of the catheter body and electrically coupled with the at least one electrical conductor. The distal tip electrode is formed with a slip resistant, field focusing exterior contour for maintaining a position of the distal tip electrode bearing against the endocardium of the patient's heart, without penetrating the myocardium thereof, achieved through manipulation of the catheter distal tip section, and focusing ablation energy into the endocardium.

Abstract: An implantable cardiac electrode includes a flexible polymeric substrate, a metallized surface layer of the polymeric substrate forming one or more electrically conductive regions on the surface of the polymeric substrate, and one or more insulated conductors connecting the electrically conductive regions to leads, the leads being connected to a cardiac monitoring and pulse generating system. In one embodiment, the electrically conductive region forms a band on the outer surface of a polymeric tube and is electrically connected to a conductor embedded in the tube. In another embodiment, the electrically conductive region forms a desired configuration on a planar surface of the polymeric substrate, such as a concentric ring or spiral patch configuration. In these and other embodiments, the metallized surface layer includes a surface layer of the polymeric substrate that is impregnated with a metal such that a conductive region is formed in the surface of the otherwise insulative polymeric substrate.

Abstract: Implantable electrode structures for use in apparatus for applying electrical therapy to a patient's heart in the treatment of arrhythmias such as tachycardias and fibrillations of the heart are herein disclosed. The electrode structures are made in the form of expandable (or self-expanding) intravascular stents for insertion through the patient's vascular system to locations in or adjacent the heart. The electrode structures can be inserted into the great veins by insertion techniques used for intravascular stent applications and provide increased electrode surfaces for discharge of electrical energy through the heart in conjunction with other strategically placed electrodes. The wire filament of the stents may be evenly spaced to form a circumferential array or may be non-uniformly spaced to form an elliptical array.

Abstract: A biocompatible thin film electrical component is configured for use in a human body or other ionic liquid environment. A polyimide substrate is bonded to a glass carrier plate sized for handling by automatic equipment and a multiple-layer metal conductor is deposited on the substrate and patterned to define an electrical circuit or biosensor. The polyimide and the glass establish a bond therebetween that withstands handling yet is broken using biocompatible releasing agents and techniques. The polyimide substrate and glass carrier plate preferably have similar thermal expansion properties to reduce the likelihood of fracture and delamination problems during release of the substrate from the carrier plate. An insulation layer covers the metal conductor and, in one embodiment, is made of a polyimide having a cure temperature lower than the temperature at which interdiffusion occurs in the metal layers in the conductor.

Abstract: A method of preparing an optical fiber for user in an interferometric system includes introducing a portion of a single-mode, polarization preserving fiber having an asymmetric cladding into a medium capable of etching away the cladding and withdrawing the portion from the medium after sensing an optical intraction between light introduced into the optical fiber and the medium.

Abstract: An optical fiber interferometric system includes a pair of single-mode, polarization-preserving fibers having distal and proximal ends. The cladding of a selected portion of one of the fibers having been removed to allow an evanescent portion of a light wave traveling within the fiber to interact with any medium surrounding the selected portion of the fiber. A light source for producing a light of known character is coupled to the proximal ends of the pair of optical fibers for introducing a source signal to the pair of fibers. A reflector at the distal ends of the optical fibers reflects the light from the distal ends back toward the light source. The return signals are used to construct an interferogram which is observed to detect any modulation in the phase of the light signals. The modulation is examined ratiometrically to derive a change in the index of refraction of the medium surrounding the selected portion substantially free of any environmentally induced phase noise.

Abstract: A biocompatible thin film electrical component is configured for use in a human body or other ionic liquid environment. A polyimide substrate is bonded to a glass carrier plate sized for handling by automatic equipment and a multiple-layer metal conductor is deposited on the substrate and patterned to define an electrical circuit or biosensor. The polyimide and the glass establish a bond therebetween that withstands handling yet is know using biocompatible releasing agents and techniques. The polyimide substrate and glass carrier plate preferably have similar thermal expansion properties to reduce the likelihood of fracture and delamination problems during release of the substrate from the carrier plate. An insulation layer covers the metal conductor and, in one embodiment, is made of polyimide having a cure temperature lower than the temperature at which interediffusion occurrs in the metal layers in the conductor.

Abstract: An elongated optical fiber apparatus for transmitting a light signal toward a first end of the apparatus situated within a fluid to be analyzed, and for transmitting a returning light signal that is indicative of a specified characteristic of the fluid toward a second end of the apparatus that is situated outside the fluid. The optical fiber apparatus includes a light conductive cable capable of transmitting light with a hole formed in its first end. Disposed substantially entirely within this hole is a reactive element that reacts with the fluid to alter a property of the light that is indicative of a specified characteristic of the fluid.