Automatically adjustable blanking period for implantable pacemaker
First Claim
1. A method of automatically generating an adjustable blanking period in a first prescribed channel of a dual chamber pacemaker, said dual chamber pacemaker having two channels:
- a first channel having means for delivering stimulation pulses to a first chamber of a heart; and
a second channel having means for delivering stimulation pulses to, and means for sensing electrical activity within, a second chamber of the heart, the sensing means of the second channel also being able to sense electrical activity that originates within the first chamber of the heart yet is detectable in the second chamber of the heart as crosstalk;
said method comprising the steps of;
(a) initiating a basic blanking interval in the second channel of said pacemaker coincident with the delivery of a stimulation pulse in the first channel, said basic blanking interval comprising a first fixed absolute refractory portion followed by a second relative refractory portion;
(b) disabling the sensing means of the second channel during the first fixed absolute refractory portion of the basic blanking interval, whereby no electrical activity of any kind is sensed by said sensing means during said first fixed absolute refractory portion;
(c) enabling the sensory means of the second channel during the second relative refractory portion of the blanking interval;
(d) restarting said basic blanking interval in response to the first occurrence of any electrical activity sensed by the sensing means of the second channel during the second relative refractory portion, said adjustable blanking period comprising the cumulative sum of said first basic blanking interval plus any restarted blanking intervals; and
(e) terminating said adjustable blanking period in the second channel in response to the earliest occurrence of either (i) the conclusion of the second relative refractory portion without the occurrence of any sensed electrical activity to restart the basic blanking interval, or (2) the conclusion of a prescribed maximum blanking period, said prescribed maximum blanking period being initiated at the delivery of the stimulation pulse in the first channel.
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Accused Products
Abstract
An automatically adjustable blanking circuit and method of generating an adjustable blanking interval for use with a dual channel implantable pacemaker includes means for generating a basic blanking interval for a first channel of the pacemaker each time a stimulation pulse is generated on a second channel. The basic blanking interval includes a first absolute refractory portion and a second relative refractory portion. During the absolute refractory portion, the sensing circuits of the first channel are disabled. During the relative refractory portion, the sensing circuits of the first channel are enabled and any activity sensed in the first channel is considered to be crosstalk or noise and the basic blanking interval is retriggered. Retriggering of the basic blanking interval continues for so long as activity is sensed in the first channel during the relative refractory portion of each retriggered basic blanking interval, up to a maximum blanking interval. If no activity is sensed during the relative refractory portion of the basic blanking interval, the blanking interval ends, and the sensing circuits of the first channel thereafter monitor the first channel for spontaneous cardiac activity.
119 Citations
32 Claims
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1. A method of automatically generating an adjustable blanking period in a first prescribed channel of a dual chamber pacemaker, said dual chamber pacemaker having two channels:
- a first channel having means for delivering stimulation pulses to a first chamber of a heart; and
a second channel having means for delivering stimulation pulses to, and means for sensing electrical activity within, a second chamber of the heart, the sensing means of the second channel also being able to sense electrical activity that originates within the first chamber of the heart yet is detectable in the second chamber of the heart as crosstalk;
said method comprising the steps of;(a) initiating a basic blanking interval in the second channel of said pacemaker coincident with the delivery of a stimulation pulse in the first channel, said basic blanking interval comprising a first fixed absolute refractory portion followed by a second relative refractory portion; (b) disabling the sensing means of the second channel during the first fixed absolute refractory portion of the basic blanking interval, whereby no electrical activity of any kind is sensed by said sensing means during said first fixed absolute refractory portion; (c) enabling the sensory means of the second channel during the second relative refractory portion of the blanking interval; (d) restarting said basic blanking interval in response to the first occurrence of any electrical activity sensed by the sensing means of the second channel during the second relative refractory portion, said adjustable blanking period comprising the cumulative sum of said first basic blanking interval plus any restarted blanking intervals; and (e) terminating said adjustable blanking period in the second channel in response to the earliest occurrence of either (i) the conclusion of the second relative refractory portion without the occurrence of any sensed electrical activity to restart the basic blanking interval, or (2) the conclusion of a prescribed maximum blanking period, said prescribed maximum blanking period being initiated at the delivery of the stimulation pulse in the first channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- a first channel having means for delivering stimulation pulses to a first chamber of a heart; and
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9. A method of automatically generating an adjustable blanking interval in a dual channel pacemaker, said adjustable blanking interval being used by a first channel of said pacemaker to blank out electrical activity present in said first channel during said blanking interval, which electrical activity, if any, is likely to be noise or crosstalk, said method comprising the steps of:
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(a) generating a basic blanking interval in a first channel of said pacemaker whenever a stimulation pulse is generated in a second channel of said pacemaker, said basic blanking interval being divided into a first portion and a second portion; (b) disregarding any electrical activity present in said first channel during said first portion of said blanking interval; (c) retriggering said basic blanking interval in response to any electrical activity present in said first channel during said second portion of said basic blanking interval; (d) repeating steps (b) and (c) for so long as electrical activity is present in said first channel during said second portion of any retriggered basic blanking interval; and (e) making said adjustable blanking interval equal to a value that varies as a function of the number of basic blanking intervals retriggered in step (c). - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. An implantable dual chamber pacemaker comprising:
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first and second channels for allowing electrical contact to be made with first and second chambers of a heart, respectively; pacemaker control logic for generating a first trigger signal when a stimulation pulse is to be presented on said first channel; sensing means for sensing electrical activity on said second channel, said sensing means generating a sense signal when such electrical activity occurs; blanking interval means for automatically generating an adjustable blanking signal pulse having a variable width, said blanking interval means being responsive to said first trigger signal and said sense signal, said adjustable blanking signal pulse commencing at a time determined by said first trigger signal and ending at a time determined by said sense signal; and means responsive to said adjustable blanking signal pulse for rejecting any electrical activity sensed by said sensing means when said adjustable blanking signal pulse is present and for accepting any electrical activity sensed by said sensing means when said adjustable blanking signal pulse is absent. - View Dependent Claims (19, 20, 21, 22, 23)
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24. Apparatus for automatically generating an adjustable blanking interval in a dual chamber pacemaker, said dual chamber pacemaker including first and second channels in which electrical activity may be sensed, said adjustable blanking interval being used in a first channel of said pacemaker to blank out electrical activity sensed in said first channel that may be noise or crosstalk originating in the second channel, said apparatus comprising:
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generating means for generating a basic blanking interval in said first channel whenever a stimulation pulse is generated in said second channel, said generating means dividing said basic blanking interval into a first portion and a second portion; first circuit means for disregarding any electrical activity present in said first channel during said first portion of said blanking interval; second circuit means for retriggering said basic blanking interval in response to any electrical activity present in said first channel during said second portion of said basic blanking interval; third circuit means for making said adjustable blanking interval equal to a value that varies as a function of the sum of a basic blanking interval and the basic blanking intervals which are thereafter retriggered by said second circuit means. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32)
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Specification