The invention generally relates to implantable medical devices and to external programmer devices used in connection therewith and in particular to methods and apparatus for processing information within an external programmer device pertaining to events recorded by the implantable medical device.
A wide range of implantable medical devices are provided for surgical implantation into humans or animals. One common example is the cardiac pacemaker. Another is the implantable cardioverter defibrillator. Other examples include devices for stimulating or sensing portions of the brain, spinal cord, muscles, bones, nerves, glands or other body organs or tissues.
Implantable medical devices, particularly pacemakers, are often configured to be used in conjunction with an external programmer device which allows a physician to program the operation of the pacemaker to, for example, control the specific parameters by which the pacemaker detects arrhythmia conditions and responds thereto. For instance, the external programmer may allow the physician to specify the sensitivity with which the pacemaker senses electrical signals within the heart and to further specify the amount of electrical energy to be employed for pacing the heart in circumstances where expected heart signals are not sensed. Additionally, the external programmer may be configured to receive and display a wide variety of diagnostic information detected by the pacemaker, such as the electrical heart signals sensed by the pacemaker and the responsive pacing signals.
With regards to the display of diagnostic information, many pacemakers operate only in real time to detect electrical activity in the heart as it occurs and to transmit data pertinent thereto to the external programmer for immediately display. In other words, no capability is provided within the pacemaker for storing sensed signals for later transmission to the external programmer. Hence, diagnostic information can only be retrieved and displayed for signals sensed by the pacemaker while the external programmer is currently communicating with the pacemaker, which is typically only while the patient in which the pacemaker is implanted is in a hospital or within a physician""s office. With such systems, only very limited information, if any, can be stored by the pacemaker for subsequent transmission to the external programmer.
U.S. Pat. No. 5,431,691 to Snell et al. entitled xe2x80x9cMethod and System for Recording and Displaying a Sequential Series of Pacing Eventsxe2x80x9d, however, provides a system employing a pacemaker and an external programmer wherein the pacemaker continuously records diagnostic data pertaining to the condition of the heart of the patient for subsequent transmission to the external programmer. The data is stored within circular buffers within the pacemaker configured to ensure that, if the buffers become full, newly recorded data overwrites the oldest previously recorded data. The recorded data is ultimately transmitted to the external programmer which is configured to provide a wide variety of different displays of the data to assist the physician in analyzing the condition of the heart and rendering appropriate diagnoses. Hence a significant improvement is achieved over previous systems that were not capable of storing diagnostic data for subsequent processing and display but were instead only capable of displaying information pertaining to the current condition of the heart. U.S. Pat. No. 5,431,691 to Snell et al. is incorporated by reference herein.
The system of Snell et al. processes and records the diagnostic data in an xe2x80x9cevent recordxe2x80x9d format which allows the data to be efficiently stored, accessed and displayed. Specific types of diagnostic data processed by the system of Snell et al. are listed in TABLE I.
As can be seen from TABLE I, the events processed by the system of the Snell et al. patent are primarily events sensed within the heart of the patient. Event records containing information pertaining to those events are recorded within the pacemaker for subsequent transmission to the external programmer for display thereon in a variety of formats including event record displays, event bar graphs, rate bar graphs, rate time graphs, and event time graphs, each under the control of the physician operating the external programmer. More specifically, the event record display presents the various detected events of TABLE I and the corresponding pacing rate with respect to the time of the occurrence of the event. For periods of time while then pacemaker is in a dual-chamber mode (such as DDD, DDI etc.), the events presented include PV, PR, AV (or V when the mode is VDDR or VDD), AR and PVC (premature ventricular contraction). For periods of time while the pacemaker is in a single-chamber mode (such as VVI, AAI etc.), the events are presented merely as paced or sensed. The event bar graph presents a histogram of different event types listing the total number of counts of each event type for a selected period of time. The event time graph presents histograms of event types vs. time of event occurrence. The rate bar graph presents histograms of sensed and paced events vs. their rate. The rate time graph presents histograms of rates vs. times. Further information regarding the different displays may be found in the Snell et al. patent.
As can be appreciated a wide range of useful information, particularly directed to events sensed within the heart, is thereby provided to assist the physician in rendering a diagnosis as to any arrhythmia or other condition the patient may exhibit or to assist the physician in making choices as to adjusting various parameters by which the pacemaker monitors and paces the heart. The information is displayed in a variety of convenient graphical formats to help the physician visualize the information quickly and easily to facilitate prompt and accurate diagnoses.
Although the system of the Snell et al. patent represents a significant improvement over previous systems, room for further improvement remains. In particular, it would be desirable to provide a system capable of recording and displaying further diagnostic data pertaining to events in addition to those which are listed in TABLE I including, for example, diagnostic data pertaining to: events detected within the heart during refractory periods following stimulation pulses; operational events triggered within the pacemaker as a result of the condition of the patient (such as an automode switching event); and operational events triggered within the pacemaker as a result of the condition of the pacemaker itself (such as battery tests or lead fault detection tests). It is to these ends that aspects of the invention are primarily directed.
In accordance with one aspect of the invention, a system is provided for detecting and displaying information received from an implantable medical device capable of generating a stimulation signal within tissue connected to the implantable medical device and capable of sensing electrical events occurring within the tissue. The system comprises means for receiving signals from the implantable medical device representative of events detected during a refractory period following generation of a stimulation signal and means for graphically displaying icons representative of the events detected during the refractory period.
In one specific example, the implantable medical device is a pacemaker and the system for detecting and displaying information is an external programmer device separate from the pacemaker. The events detected during the refractory period include the detection of: a) a P-wave during a relative Post-Ventricular Atrial Refractory Period (PVARP) not followed by a ventricular pulse; b) an R-wave during a relative Ventricular Refractory Period; or c) a P-wave during an Atrial Refractory Period during an AV/PV interval. The means for graphically displaying the detected events is a computer display screen or a computer print-out device.
In accordance with another aspect of the invention, a system is provided for detecting and displaying information received from an implantable medical device capable of being programmed by signals received from a remote programming device. The system comprises means for receiving signals from the implantable medical device representative of programming operations triggered within the implantable medical device by the signals received from the remote programming device and means for graphically displaying icons representative of the programming operations triggered within the implantable medical device.
In one specific example, wherein the implantable medical device includes a pacemaker, the programming operations triggered within the pacemaker are selected from a group consisting of pacemaker mode selection, heart base rate selection, heart rest rate selection, maximum pacemaker tracking rate selection, maximum pacemaker sensing rate selection and pacemaker rate responsive AV/PV delay selection. The remote programming device may be a magnet operated by a physician or may be part of a programmer unit operated by a physician.
In accordance with yet another aspect of the invention, a system is provided for detecting and displaying information received from an implantable medical device that is capable of triggering internal operations based upon sensed conditions. The system comprises means for receiving signals from the implantable medical device representative of operations triggered by the implantable medical device in response to conditions sensed within the implantable medical device and means for graphically displaying icons representative of the operations triggered within the implantable medical device.
In one example, wherein the implantable medical device includes a pacemaker, the pacemaker is capable of sensing conditions of the heart of a patient in which the pacemaker is implanted. The aforementioned operations are triggered based upon the sensed conditions of the heart and include operations such as automatic pacemaker mode switching (i.e. automode switching), pacemaker mediated tachycardia (PMT) detection, premature ventricular contraction (PVC) detection, and a pacemaker rate hysteresis search.
In another example, wherein the implantable medical device again includes a pacemaker, the pacemaker is capable of sensing performance parameters representative of its own performance. The operations triggered within the pacemaker are triggered based upon the sensed performance parameters and include operations such as a battery test and a lead fault detection test.
Hence, with the invention, systems are provided for graphically displaying a wide variety of diagnostic information not heretofore easily available to the physician, to thereby assist the physician in making quick and informed decisions regarding, for example, the patient""s condition or the condition of the implantable medical device.
Other objects and advantages of the invention are provided as well. Method embodiments of the invention are also provided.