His Bundle Pacing Timing for Reliable Cardiac Impedance Sensing
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Solution Overview
Problem
Conventional implantable medical devices cannot measure cardiac impedance effectively when using a His bundle electrode, as the usual methods for measuring impedance in the right ventricle are not applicable, and impedance measurement is crucial for assessing heart contractility.
Innovation Solution
An implantable medical device with a stimulation unit and a detection unit, including an electrode, that delivers a stimulation pulse followed by a first period for signal measurement and a second period for impedance measurement, allowing for reliable impedance measurement by accounting for the physiological delay in heart contraction and enabling detailed intracardiac electrogram recording before impedance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a His bundle electrode is used for stimulation, then physiologic stimulation of the heart is achieved, but conventional impedance measurement methods are no longer available
Solution Approach 1:
The patent changes the timing parameters for impedance measurement by introducing a delayed measurement window (starting at least 35ms after stimulation pulse) and modifies the measurement approach to be compatible with His bundle electrode physiology, thereby enabling impedance measurement with this specialized electrode configuration
Solution Approach 2:
The patent performs preliminary actions by first delivering the stimulation pulse to the His bundle, then waiting for a predetermined time period (at least 35ms) before initiating impedance measurement, ensuring that the measurement is taken at an appropriate physiological moment when the heart muscle has had time to contract
2Ease of operation
If impedance measurement is performed immediately after stimulation pulse, then measurement timing is simplified, but measurement accuracy is reduced due to physiological delay in heart contraction
Solution Approach 1:
The patent performs preliminary stimulation and waits for physiological response before measurement, introducing a time delay of at least 35ms between stimulation pulse and impedance measurement to allow heart muscle contraction to occur, thereby improving measurement accuracy
Solution Approach 2:
The patent introduces dynamic timing adjustments by allowing the impedance measurement to be performed at variable time points (at least 35ms after stimulation pulse), adapting the measurement timing to the physiological response characteristics of the heart
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables reliable cardiac impedance measurement with a His bundle electrode, providing accurate information on heart contractility and cardiac rhythm, even when conventional methods are not feasible, and allows for adjustments in stimulation parameters based on measured impedance.
Implementation Method 1
The stimulation unit (17) is configured to stimulate the His bundle (18) of a human or animal heart (6)
Implementation Method 2
When the first period of time is terminated (i.e., directly at the end of the first period of time), an electric signal at the His bundle (18) of the same heart (6) is measured with the detection unit (19)
Implementation Method 3
When the second period of time is terminated (i.e., directly at the end of the second period of time), an impedance of the same heart (6) is measured with the detection unit (19)
Data Source
AI summary
An implantable medical device for stimulating a human/animal heart, comprising a housing, a processor, a memory unit, a stimulation unit configured to stimulate the His bundle, and a detection unit configured to detect an electrical signal at the His bundle. The device performs: a) stimulating the His bundle with a stimulation pulse delivered by the stimulation unit; b) measuring an electric signal at the His bundle with the detection unit upon termination of a first period of time starting upon delivering of the stimulation pulse, wherein the first period of time is from 35 ms to 500 ms; c) measuring an impedance of the same heart with the detection unit upon termination of a second period of time starting upon delivering of the stimulation pulse, wherein the second period of time is equal to or longer than the first period of time and is from 50 ms to 500 ms.