Electronic capture detection for a pacer
First Claim
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1. Apparatus for detecting a depolarization cardiac tissue evoked by a packing pulse, comprising:
- a pulse generator for generating pacing pulses;
means for applying said pacing pulses to the heart;
first and second electrodes for sensing cardiac signals;
a virtual load connected to said first electrodean active circuit, coupled to said second electrode and said virtual load, for providing electrical energy to said first electrode through said virtual load in response to the occurrence of a cardiac depolarization to counteract depolarization induced variation in the relative electrode/electrolyte equilibrium of said first and second electrodes;
a monitoring circuit, coupled to said active circuit, for monitoring electrical energy provided through said virtual load, for detecting the occurrence of a cardiac depolarization;
a capture detect timer defining a capture detect window after the generation of a pacing pulse by said pulse generator; and
capture detect logic responsive to said monitoring circuit and said capture detect timer for detecting the occurrence of a cardiac depolarization accruing within said capture detect window.
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Abstract
A pacemaker sense amplifier which includes active circuitry which establishes and attempts to maintain a constant field density between two electrodes, effectively clamping them together at substantially fixed relative electrical potentials. The amount of current or power provided to the electrodes monitored and forms the basis of detection of the passing cardiac depolarization wavefront. A timer is sued to define a detection window after the generation of a pacing pulse. The occurrence of a detected depolarization within the detection window is indicates that the pacing pulse has captured the heart.
78 Citations
12 Claims
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1. Apparatus for detecting a depolarization cardiac tissue evoked by a packing pulse, comprising:
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a pulse generator for generating pacing pulses; means for applying said pacing pulses to the heart; first and second electrodes for sensing cardiac signals; a virtual load connected to said first electrode an active circuit, coupled to said second electrode and said virtual load, for providing electrical energy to said first electrode through said virtual load in response to the occurrence of a cardiac depolarization to counteract depolarization induced variation in the relative electrode/electrolyte equilibrium of said first and second electrodes; a monitoring circuit, coupled to said active circuit, for monitoring electrical energy provided through said virtual load, for detecting the occurrence of a cardiac depolarization; a capture detect timer defining a capture detect window after the generation of a pacing pulse by said pulse generator; and capture detect logic responsive to said monitoring circuit and said capture detect timer for detecting the occurrence of a cardiac depolarization accruing within said capture detect window. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A cardiac pacemaker, comprising:
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a pulse generator for generating pacing pulses; means for applying said pacing pulses to cardiac tissue; means for detecting the depolarizations of cardiac tissue evoked by said pacing pulses, said detecting means comprising a first electrode means for location proximate said cardiac tissue, a second electrode, a virtual load connected to said first electrode, charge supplying means coupled to said virtual load and to said second electrode for maintaining said first electrode at a stead state of electrical potential relative to said second electrode and monitoring means for monitoring the current through said virtual load required to maintain said steady state during the occurrence of a cardiac depolarization; a capture detect timer defining a capture detect window after the generation of a pacing pulse by said pulse generator; and capture detect logic responsive to said monitoring circuit and said capture detect timer for detecting the occurrence of a cardiac depolarization occurring within said capture detect window. - View Dependent Claims (12)
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Specification