News Column

Patent Issued for Device and Method for Identifying Cardiac Events

August 18, 2014



By a News Reporter-Staff News Editor at Cardiovascular Week -- From Alexandria, Virginia, NewsRx journalists report that a patent by the inventors Wang, Hanbiao (Woodland Hills, CA); Dai, Bonian (Temple City, CA); Ahmadi, Iman (Valencia, CA); Brockman, Erik (Saratoga, CA), filed on April 6, 2010, was published online on August 5, 2014 (see also Pacesetter, Inc.).

The patent's assignee for patent number 8798733 is Pacesetter, Inc. (Sylmar, CA).

News editors obtained the following quote from the background information supplied by the inventors: "An implantable medical device (IMD) is implanted in a patient to monitor, among other things, electrical activity of a heart and to deliver appropriate electrical therapy, as required. IMDs include pacemakers, cardioverters, defibrillators, implantable cardioverter defibrillators (ICD), and the like. The electrical therapy produced by an IMD may include pacing pulses, cardioverting pulses, and/or defibrillator pulses to reverse arrhythmias (e.g., tachycardias and bradycardias) or to stimulate the contraction of cardiac tissue (e.g., cardiac pacing) to return the heart to its normal sinus rhythm. These pulses are referred to as stimulus or stimulation pulses.

"In order to determine when stimulus pulses are to be applied to the heart, the IMDs identify cardiac events of the heart and, based on the cardiac events, supply or withhold the stimulus pulses to the heart. By way of example, the cardiac events may include cardiac signal waveform segments, segments of cardiac signals between waveform segments, heart rates, and the like.

"The accurate identification of cardiac events is desirable to ensure that stimulus pulses are applied to the heart when needed and are withheld when unnecessary. Some known IMDs use time-domain processing techniques to identify cardiac events. For example, the IMDs may compare the cardiac signals to a threshold and classify the cardiac signals as indicative of a cardiac event every time the cardiac signals extend above the threshold. But, identifying cardiac events based on comparisons between cardiac signals and a threshold can be prone to errors. For example, in some patients a QRS complex may be misidentified as a T-wave, and vice-versa.

"The battery energy reserves of some known IMDs limit the amount of computational resources that are implemented in analysis methods that may be used by the IMDs to identify cardiac events based on cardiac signals. For example, the battery energy reserves of some known IMDs are too small to permit the IMDs to engage in costly frequency domain processing techniques such as Fourier transforms and wavelet transforms. As a result, some known IMDs are limited to the simple time-domain processing techniques such as comparing cardiac signals to a single threshold.

"A need exists for an IMD that more accurately identifies cardiac events while avoiding costly processing techniques that consume the battery energy reserves of the IMDs."

As a supplement to the background information on this patent, NewsRx correspondents also obtained the inventors' summary information for this patent: "In one embodiment, an implantable medical device is provided. The implantable medical device includes leads having electrodes that are positioned within a heart. The electrodes sense signals derived from the heart that include waveform segments. The device includes a timing module that determines when the waveform segments cross a threshold and measures time intervals between at least two threshold crossings by the waveform segments. The device also includes event identification module that compares the time intervals to a predetermined pattern associated with a cardiac event. The event identification module identifies the cardiac event based on the time intervals and the predetermined pattern.

"In another embodiment, a method for identifying cardiac events is provided. The method includes sensing signals derived from a heart that include waveform segments and determining when the waveform segments cross a threshold. The method also includes measuring time intervals between at least two threshold crossings by waveform segments and comparing the time intervals to a predetermined pattern associated with the cardiac event. The method further includes identifying the cardiac event based on the time intervals and the predetermined pattern.

"In another embodiment, a computer-readable storage medium for use in a medical device having a memory and a programmable controller is provided. The computer readable storage medium includes instructions to direct the memory to store a threshold, a pattern, and signals having waveform segments that are derived from a heart. The instructions also direct the controller to determine when the waveform segments cross a threshold and measure time intervals between at least two crossings of the threshold by the waveform segments. The instructions further direct the controller to compare the time intervals to the pattern that is associated with a cardiac event and to identify the cardiac event based on the time intervals and the pattern."

For additional information on this patent, see: Wang, Hanbiao; Dai, Bonian; Ahmadi, Iman; Brockman, Erik. Device and Method for Identifying Cardiac Events. U.S. Patent Number 8798733, filed April 6, 2010, and published online on August 5, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8798733.PN.&OS=PN/8798733RS=PN/8798733

Keywords for this news article include: Cardiology, Cardio Device, Pacesetter Inc, Medical Devices.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Cardiovascular Week


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