Radio frequency antenna in a header of an implantable medical device

#This subject matter pertains to implantable medical devices such as cardiac pacemakers and implantable cardioverter/defibrillators. In particular, the subject matter relates to an apparatus and method for enabling radio frequency telemetry in such devices.

#Implantable medical devices, including cardiac rhythm management devices such as pacemakers and implantable cardioverter/defibrillators, usually have the capability to communicate data with a device called an external programmer via a radio frequency telemetry link. A clinician may use an external programmer to program the operating parameters of an implanted medical device. For example, the pacing mode and other operating characteristics of a pacemaker may be modified after implantation in this manner. Modern implantable devices also include the capability for bidirectional communication so that information can be transmitted to the programmer from the implanted device. Among the data which may be telemetered from an implantable device are various operating parameters and physiological data, the latter either collected in real-time or stored from previous monitoring operations.

#Telemetry systems for implantable medical devices utilize radio frequency energy to enable bidirectional communication between the implantable device and an external programmer. A radio frequency carrier is modulated with digital information by, for example, amplitude shift keying where the presence or absence of pulses in the signal constitute binary symbols or bits. The external programmer transmits and receives the radio signal with an antenna incorporated into a wand which can be positioned in proximity to the implanted device. The implantable device also generates and receives the radio signal by means of an antenna formed by a wire coil wrapped around the periphery of the inside of the device casing.

#FIGS. 1A, 1B, 1C and 1D schematically illustrate various antenna configurations disposed in a header of an implantable device.

#FIGS. 2A and 2B illustrate electrical schematics for selected antenna configurations.

#FIG. 3A includes a perspective view of a header coupled to an implantable device.

#In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown, by way of illustration, specific embodiments in which the present subject matter may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the subject matter, and it is to be understood that the embodiments may be combined, or that other embodiments may be utilized and that structural, mechanical, logical and electrical changes may be made without departing from the scope of the present subject matter. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present subject matter is defined by the appended claims and their equivalents.

#As noted above, conventional radio frequency (RF) telemetry systems used for implantable medical devices such as cardiac pacemakers utilize inductive coupling between the antennas of the implantable device and an external programmer in order to transmit and receive radio frequency signals. Because the induction field produced by a transmitting antenna falls off rapidly with distance, such systems require close proximity between the implantable device and a wand antenna of the external programmer in order to work properly, usually on the order of a few inches.

#The present subject matter, on the other hand, includes an apparatus and method for enabling telemetry with an implantable medical device utilizing far-field radiation. Communication using far-field radiation can take place over much greater distances which makes it more convenient to use an external, or remote, programmer. Also, the increased communication range makes possible other applications of the telemetry system such as remote monitoring of patients and communication with other types of external devices.