Abstract: A method and apparatus for treating gastric arrhythmia. The apparatus features an implantabler pulse generator which may be coupled to the gastric system through one or more medical electrical leads. In the preferred embodiment the leads couple to the circular muscle layer of the stomach. The apparatus further features a sensor to sense slow waves and determines whether the slow waves are occurring in an irregular or unstable manner. The apparatus further permits such slow waves to be diagnosed as either occurring in a bradygastria or a tachygastria and provides the appropriate electrical stimulation in response. Thus the present invention diagnoses and treats irregular gastric rhythm such as bradygastria and tachygastria.

Abstract: There is provided a system and method for determining, in a DDD or DDD(R) pacing system, when a delivered atrial pace pulse has failed to capture the patient's atrium. Each cycle, following a delivered ventricular pace pulse, or every N cycles a measure of change in QT interval is obtained and compared to stored criteria. When an atrial pulse has achieved capture, the difference in QT from the last beat will be small, normally less than 2 ms. However, if there has not been atrial capture, the delivered ventricular pace pulse is in fact asynchronous with respect to the atrium, and under these circumstances the change in QT is greater than 2 ms, e.g., in the range of 2-10 ms. Accordingly, when the pacemaker sees a change in QT within the 2-10 ms range, this indicates failure of capture, and responsive action is taken by either directly incrementing the energy level of the atrial pace pulses, or performing an atrial threshold search and then resetting the atrial pace energy level.

Abstract: An implantable drug infusion device which features an improved flow regulator which permits the flow rate to be independent of reservoir pressure within a given pressure range. The flow regulator features a membrane having a hole, the membrane itself positioned above a bottom layer such that sufficient deflection of the membrane causes the membrane to engage against the bottom layer. As liquid flows through the hole a drag force is applied to the edge of the hole resulting in a deflection of the membrane. Once contact is made between the membrane and the bottom layer, then flow reduced. In a further embodiment the bottom layer features a variable flow channel such that upon membrane deflection flow may only proceed through the hole and through the flow channel. By tailoring the shape and length of the variable flow channel the flow characteristics of the regulator versus pressure may be adjusted. In a further embodiment the flow regulator also features a flow sensor integrated therewith.

Abstract: An ambulatory data recorder with enhanced infrared data transfer. In particular, the device features an infrared transmitter port having a multi-plane lens. The port, lens and recorder enclosure work together to permit a reliable infrared data link to be established between the recorder and a line voltage device even while the recorder is in a variety of positions. That is, the infrared data link may be established when the device is worn, of when the device is placed on a table in a variety of positions.

Abstract: A pulse waveform is provided to at least one surface of an implantable device to protect it from corrosion from a corrosive fluid. The pulse waveform can be delivered through ether anodic or cathodic monophasic or asymetrical biphasic pulses using one electrode and an indiferent or sacrificial electrode. The electrode and the indiferent or sacrificial electrode are oriented such that a closed circuit between the two electrodes is completed through the corrosive fluid and the surface to be protected is within the completed circuit path.

Abstract: Methods for making bioprosthetic devices made of collagen-based material having collagen amine groups and collagen carboxyl groups are provided. The methods include blocking at least a portion of the collagen amine groups with a blocking agent, activating at least a portion of the collagen carboxyl groups after blocking at least a portion of the collagen amine groups to form activated carboxyl groups, and contacting the activated collagen carboxyl groups with a polyfunctional spacer to crosslink the collagen-based material.

Abstract: There is provided a cardiac pacemaker system with a ventricular tachycardia prevention feature, whereby the pacemaker monitors ventricular activity during each patient awakening period to determine when VT is likely. In a preferred embodiment, QRS and T wave templates are generated cyclically during awakening, and compared to normal templates to obtain a measure of variability, indicative of refractory dispersion and thus of probable VT. Ventricular extra-systoles are also monitored and analyzed during the awakening period to see how closely they occur to the ventricular vulnerable period. When the monitored data indicates VT probability during awakening, the pacemaker responds by overdriving the heart with an intervention pacing rate which is continually adjusted as a function of the currently obtained data.

Abstract: A catheter having a multiple locking mechanism for connecting a proximal portion of the catheter shaft to a distal portion of the catheter shaft is provided. Also provided is a method for connecting a catheter shaft employing the multiple locking mechanism of the invention. The multiple locking mechanism permits a proximal shaft to be joined with a distal end portions, while simultaneously ensuring integrity of the connection between the proximal shaft and the distal end portion.

Abstract: An ambulatory recorder having real time non-real time processors is described. The real time processor handles sampling functions while the non real time processor handles other functions, such as high processing operations associated with multitasking, graphical user interface, floating point calculation, Infra Red communication and long term memory storage. The second processor is primarily provided to operate a Windows CE operating system as well as one or more embedded applications. Through this design, electrical power provided by a battery is only consumed by those components essential to device operation at any particular time.

Abstract: There is provided an implantable device system such as a battery-powered pacemaker system, with an improved capability of measuring battery internal impedance, thereby providing the means to determine anticipated device End of Life. Within one pacemaker cycle following a sensed beat or a delivered stimulus, and before delivery of a next stimulus, three battery measurements are taken at equally spaced time intervals. Due to the RC nature of the battery internal impedance, the first two battery voltage measurements can be used to calculate what the voltage would be at the third time, assuming no change in current load. At the third time, a predetermined incremental current load is added, and the battery voltage at the time of the added current load is measured. The voltage differential between the calculated battery voltage and the measured battery voltage at the third time, together with the predetermined incremental current load, is used to calculate the battery impedance.

Abstract: The present invention provides a pacing system with a lead having a fixation element for providing stable fixation relative to the junction of the left and right brachiocephalic veins of the patient. In a first embodiment, a short tine element is provided for engaging the brachiocephalic junction. The present invention also provides a pacing system with a lead having a fixation element for providing stable fixation relative to the atrium and the SVC of the patient. In another embodiment, a three-pronged tine is provided for engaging the portion of the atrium adjacent the SVC.

Abstract: An ambulatory recorder having an enhanced ergonomic case is described. The case has a smooth curved semi-circular surface within a first plane along the top surface while further having an at least partially curved surface along a second end. These curved surfaces render the recorder less likely to be caught on objects or on the patient's arms or hands while worn. The recorder is thus more comfortable to wear and operate.

Abstract: A system and method of providing for cardiac pacing which incorporates modulation of the pacing rate in order to minimize variations in ventricular power output, e.g., variation related to patient respiratory phases. In a preferred embodiment, pacing rate is increased during inspiration relative to expiration, to restore a measure of the normal rate modulation which occurs in a normal person. Patient respiration is monitored and a respiration signal is processed to determine the timing of rate modulation. Parameters representative of respiratory changes, such as right ventricular volume and right ventricular blood pressure are also monitored and, together with respiration amplitudes changes, are used to determine an incremental rate signal for controlling the extent of rate variation.

Abstract: An ambulatory data recorder having a slidable patient activity period switch. The slidable patient activity period switch permits the patient to slide the switch from a first position to a second position upon the start of a pre-defined activity, e.g. eating. Upon completion of the pre-defined activity, the switch is slide from the second position back to the first position. While in either the first or second position the switch position corresponds to a marking on the recorder enclosure such that the patient can readily understand which activity the switch is indicating. The slidable patient activity period switch is further configured to have minimal power consumption. In one embodiment the switch is provided through a standard keyboard interrupt service routine.

Abstract: There is provided an implantable system and method for monitoring pancreatic beta cell electrical activity in a patient in order to obtain a measure of a patient's insulin demand and blood glucose level. A stimulus generator is controlled to deliver stimulus pulses so as to synchronize pancreatic beta cell depolarization, thereby producing an enhanced electrical signal which is sensed and processed. In a specific embodiment, the signal is processed to determine the start and end of beta cell depolarization, from which the depolarization duration is obtained. In order to reduce cardiac interference, each stimulus pulse is timed to be offset from the QRS signal which can interfere with the pancreas sensing. Additionally, the beta cell signals are processed by a correction circuit, e.g., an adaptive filter, to remove QRS artifacts, as well as artifacts from other sources, such as respiration.

Abstract: A pacing system and method for determining a heart failure condition such as left ventricular dysfunction in a patient are provided, based upon obtaining information from cardiac signals, which information is processed and examined for an indication of the onset or progression of LVD. Since LVD is generally characterized by conduction disorders and other body responses calling for different heart rates during exercise, an examination of sensed cardiac signals is utilized to obtain data reflective of an LVD condition. In one embodiment, a QT rate responsive pacemaker is utilized, wherein variations in QT interval corresponding to heart rate are detected and stored, and then periodically analyzed to detect changes of sufficient magnitude to indicate onset of LVD. In another embodiment, changes in lower natural rate at nighttime or rest are monitored and analyzed for detection for a trend indicating LVD.

Abstract: A device for treating sleep apnea comprising means for detecting an apnea event and means responsive to detection of an apnea event for stimulating the heart at a higher rate than the heart's natural rate.

Abstract: There is provided a pacemaker system having the feature of delivering a ventricular safety pulse (VSP) following an early ventricular sense (VS), wherein the pacemaker automatically determines whether VSPs are to be delivered following early VSs, and if yes, with what timing. The pacemaker gathers data following delivered VSPs, which data contains information indicative of whether each early VS was indeed the result of a spontaneous R wave, or was due to crosstalk from a prior delivered atrial pace pulse. This data is processed and, when it presents a high statistical confidence, is used to make a determination of whether to respond with the assumption of a true R wave, or of crosstalk. If the data is not statistically significant, the pacemaker delivers VSPs in a normal fashion, e.g., at the end of a programmable VSP interval timed out following delivery of an atrial pace pulse.

Abstract: An ambulatory recorder having a volatile and a non-volatile memory is described. The recorder actively manages the transfer of the data in the volatile to the non-volatile memory. In particular, the sampling frequency and number of channels to be sampled are monitored. These parameters, along with the total buffer size available, are used to determine the final complete data set which can be stored in the buffer. Thereafter, the contents of the buffer are transferred to the non-volatile memory. In such a manner the recorder avoids filling the buffer in the middle of a sampling tick, in which case the remaining data to be sampled would be lost.

Abstract: There is provided an implantable device with two or more output stages for delivering concurrent output pulses to two or more sites within a patient's body. Each output circuit has a common architecture, including a switchable generator which has a plurality of storage capacitors and switches for arranging the capacitors either to be charged by the battery, or to discharge a stimulus pulse. A programmable regulator is provided for further regulation of the output voltage; and a multiplexer connects the output to the desired electrodes placed at the patient site.