Leadless Pacemaker Rate Control via External Activity Sensor
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Solution Overview
Problem
Leadless Cardiac Pacemakers (LCPs) face challenges in providing rate-responsive pacing due to noise in accelerometer data from heart movement and difficulty in deriving reliable measures of respiration rate and tidal volume, limiting their ability to adjust pacing rates based on patient activity.
Innovation Solution
A system that includes a Leadless Cardiac Pacemaker (LCP) sensing cardiac electrical data and receiving patient activity data wirelessly from an implanted device, allowing the LCP to adjust pacing therapy based on sensed activity levels, including respiration information derived from transthoracic impedance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If an LCP uses a local accelerometer to sense patient activity, then activity detection capability is provided, but the accelerometer data contains significant noise from heart movement making reliable detection difficult
Solution Approach 1:
The patent introduces an external implanted medical device as an intermediary to sense patient activity. This external device is positioned away from the heart, so it does not experience the same movement noise that plagues local accelerometers. The external device acts as a mediator that provides clean activity data to the LCP without being contaminated by cardiac motion artifacts.
Solution Approach 2:
The patent divides the sensing function into two separate components: the LCP remains responsible for pacing therapy delivery, while an external implanted device handles the activity sensing function. This segmentation allows each device to be optimized for its specific function, with the external device positioned to avoid heart movement interference while the LCP focuses on precise cardiac pacing.
2Ease of operation
If an LCP is made compact for implantation, then ease of implantation and reduced invasiveness are achieved, but the device size limits the capacity for housing high capacity battery and processing power needed for rate responsive pacing
Solution Approach 1:
The patent divides the pacemaker system into two separate implanted devices: a compact LCP for pacing therapy delivery and an external implanted device for activity sensing and processing. This segmentation allows the LCP to remain small and easy to implant while the external device can house the necessary processing power and battery capacity for rate responsive functionality.
Solution Approach 2:
The external implanted device serves multiple functions: it senses patient activity, derives respiration information, processes this data to determine appropriate pacing rates, and communicates with the LCP. This multi-functionality consolidates the computational and sensing capabilities that would otherwise need to be housed within the LCP itself.
3Reliability
If an LCP is positioned close to the heart for effective pacing, then pacing efficacy is improved, but it becomes difficult to derive reliable measures of respiration rate and tidal volume
Solution Approach 1:
The patent uses an external implanted device as an intermediary for respiration sensing. This external device is positioned away from the heart in a location where it can detect respiration-related movements and impedance changes without being contaminated by cardiac motion. It then processes this data to derive accurate respiration rate and tidal volume measurements.
Solution Approach 2:
The patent replaces direct mechanical sensing of respiration at the heart location with wireless communication of processed respiration data. The external device performs the mechanical sensing and signal processing functions remotely, then transmits the derived respiration parameters to the LCP, eliminating the need for the LCP to directly measure respiration signals.
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 more accurate and responsive pacing adjustments, improving the LCP's ability to match pacing rates with patient activity levels, thereby enhancing the management of heart activity and quality of life for patients.
Implementation Method 1
respiration information, such as respiration rate and tidal volume, may be derived from the patient activity data signal (e.g. a change in amplitude of the patient activity data signal over time)
Data Source
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AI summary
Systems and methods for providing rate responsive pacing therapy to a heart of a patient. One example method for providing rate responsive pacing therapy includes sensing cardiac electrical data with a leadless cardiac pacemaker (LCP) that is implanted within or proximate the heart. From this location, the LCP may provide pacing therapy to the heart based at least in part on the sensed cardiac electrical data. An implantable medical device located remotely from the heart may sense patient activity, and may wirelessly communicate patient activity data from the implantable medical device to the LCP, sometimes using conducted communication. The LCP may be then determine an adjustment to the provided pacing therapy (e.g. adjust the pacing rate) based at least in part on the received patient activity data signal.