Distinguishing premature contractions in a medical device

Abstract

A method and device of distinguishing premature contractions that includes a sensor sensing cardiac signals, and a processor configured to determine a plurality of R-waves in response to the sensed cardiac signal, detect a premature contraction being associated with a first R-wave of the plurality of R-waves, determining a first area of the detected first R-wave, determine a second area of a second R-wave, determine a ratio of the first area and the second area, compare the ratio to a ratio threshold, and identify the detected premature contraction as one of a premature atrial contraction or a premature ventricular contraction in response to the comparing..

1 . A method of distinguishing cardiac signals in a medical device, comprising:
 sensing cardiac signals;   determining a plurality of R-waves in response to the sensed cardiac signal;   detecting a premature contraction being associated with a first R-wave of the plurality of R-waves;   determining a first area of the detected first R-wave;   determining a second area of a second R-wave;   determining a ratio of the first area and the second area;   comparing the ratio to a ratio threshold; and   identifying the detected premature contraction as one of a premature atrial contraction or a premature ventricular contraction in response to the comparing.   
     
     
         2 . The method of  claim 1 , further comprising at least one of generating an alert and storing the identifying of the detected premature contraction. 
     
     
         3 . The method of  claim 1 , wherein the detected premature contraction is identified as a premature atrial contraction in response to the ratio not being greater than the ratio threshold and as a premature ventricular contraction in response to the ratio being greater than the ratio threshold. 
     
     
         4 . The method of  claim 3 , wherein the ratio threshold corresponds to a percentage change of the ratio. 
     
     
         5 . The method of  claim 1 , further comprising:
 computing a morphology metric of an R-wave and a corresponding preceding morphology metric of an immediately preceding R-wave;   comparing one of a difference and a ratio of the R-wave morphology metric and the preceding R-wave morphology metric to the detection threshold;   detecting a premature ventricular contraction in response to the comparison meeting the detection threshold requirement;   determining intervals between consecutive R-waves;   detecting a premature coupling interval; and   computing the R-wave morphology metric and the preceding R-wave morphology metric in response to detecting the premature coupling interval.   
     
     
         6 . The method of  claim 1 , further comprising:
 computing a morphology metric of an R-wave and a corresponding preceding morphology metric of an immediately preceding R-wave;   comparing one of a difference and a ratio of the R-wave morphology metric and the preceding R-wave morphology metric to the detection threshold; and   detecting a premature ventricular contraction in response to the comparison meeting the detection threshold requirement, wherein computing the morphology metric comprises:   identifying a fiducial point along the R-wave;   establishing a first time interval ending at the fiducial point;   establishing a second time interval beginning at the fiducial point; and   computing a first area over the first time interval and a second area over the second time interval.   
     
     
         7 . The method of  claim 6 , wherein the first time interval has a first length and the second time interval has a second length different from the first length. 
     
     
         8 . The method of  claim 7 , wherein the morphology metric is a sum of the first area and the second area. 
     
     
         9 . The method of  claim 1 , further comprising computing a measurement of the sensed ventricular R-waves in response to detecting the premature ventricular contraction. 
     
     
         10 . The method of  claim 9 , wherein computing a measurement of the sensed ventricular R-waves comprises computing a heart rate turbulence measurement. 
     
     
         11 . A medical device for distinguishing cardiac signals, comprising:
 a sensor sensing cardiac signals; and   a processor configured to determine a plurality of R-waves in response to the sensed cardiac signal, detect a premature contraction being associated with a first R-wave of the plurality of R-waves, determining a first area of the detected first R-wave, determine a second area of a second R-wave, determine a ratio of the first area and the second area, compare the ratio to a ratio threshold, and identify the detected premature contraction as one of a premature atrial contraction or a premature ventricular contraction in response to the comparing.   
     
     
         12 . The device of  claim 11 , wherein the processor is further configured to at least one of generate an alert and store the identified detected premature contraction. 
     
     
         13 . The device of  claim 11 , wherein the detected premature contraction is identified as a premature atrial contraction in response to the ratio not being greater than the ratio threshold and as a premature ventricular contraction in response to the ratio being greater than the ratio threshold. 
     
     
         14 . The device of  claim 13 , wherein the ratio threshold corresponds to a percentage change of the ratio. 
     
     
         15 . The device of  claim 11 , wherein the processor is further configured to compute a morphology metric of an R-wave and a corresponding preceding morphology metric of an immediately preceding R-wave, compare one of a difference and a ratio of the R-wave morphology metric and the preceding R-wave morphology metric to the detection threshold, detect a premature ventricular contraction in response to the comparison meeting the detection threshold requirement, determine intervals between consecutive R-waves, detect a premature coupling interval, and compute the R-wave morphology metric and the preceding R-wave morphology metric in response to detecting the premature coupling interval. 
     
     
         16 . The device of  claim 11 , wherein the processor is further configured to compute a morphology metric of an R-wave and a corresponding preceding morphology metric of an immediately preceding R-wave, compare one of a difference and a ratio of the R-wave morphology metric and the preceding R-wave morphology metric to the detection threshold, and detect a premature ventricular contraction in response to the comparison meeting the detection threshold requirement, wherein computing the morphology metric comprises:
 identifying a fiducial point along the R-wave;   establishing a first time interval ending at the fiducial point;   establishing a second time interval beginning at the fiducial point; and   computing a first area over the first time interval and a second area over the second time interval.   
     
     
         17 . The device of  claim 16 , wherein the first time interval has a first length and the second time interval has a second length different from the first length. 
     
     
         18 . The device of  claim 17 , wherein the morphology metric is a sum of the first area and the second area. 
     
     
         19 . The device of  claim 11 , wherein the processor is further configured to compute a measurement of the sensed ventricular R-waves in response to detecting the premature ventricular contraction. 
     
     
         20 . The device of  claim 19 , wherein computing a measurement of the sensed ventricular R-waves comprises computing a heart rate turbulence measurement. 
     
     
         21 . A non-transitory computer readable medium storing instructions which cause a medical device to perform a method, the method comprising:
 sensing cardiac signals;   determining a plurality of R-waves in response to the sensed cardiac signal;   detecting a premature contraction being associated with a first R-wave of the plurality of R-waves;   determining a first area of the detected first R-wave;   determining a second area of a second R-wave;   determining a ratio of the first area and the second area;   comparing the ratio to a ratio threshold; and   identifying the detected premature contraction as one of a premature atrial contraction or a premature ventricular contraction in response to the comparing.