Segmented Wireless Cardiac Stimulator Modules
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Solution Overview
Problem
Conventional cardiac pacemaker and defibrillator systems face challenges in minimizing device size and weight due to battery longevity issues, leading to frequent surgical replacements and potential dislodgement of implantable pulse generators (IPGs) due to patient movement, especially in patients with minimal muscle or fat tissue in the chest area.
Innovation Solution
The implementation of a wireless cardiac stimulation system with two separately implantable modules: a transmitter module housing ultrasonic transducers and control electronics, and a battery module connected via a power and communication cable, allowing for optimized energy transmission and reduced device size and weight, with features like suture points for stabilization and sensing electrodes for monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the IPG is placed in the pectoral region with leads connected to vascular access, then surgical accessibility and lead insertion are facilitated, but the device mass and volume increase due to the enclosed battery
Solution Approach 1:
The IPG is divided into two separate modules: a transmitter module containing ultrasonic transducers and control electronics, and a battery module containing the power source. These modules are implanted separately and connected via a flexible cable, allowing the battery mass to be distributed away from the transmitter site, reducing the effective weight at the pectoral implantation location while maintaining surgical accessibility.
2Duration of action of stationary object
If the battery size is increased to extend longevity beyond patient lifetime, then fewer surgical replacements are needed, but the device volume and weight increase
Solution Approach 1:
By separating the battery module from the transmitter module, the system allows for selective replacement of only the battery module when power is depleted, rather than replacing the entire IPG. This segmentation enables extended battery longevity without proportionally increasing the volume of the transmitter module that remains permanently implanted.
Solution Approach 2:
The battery module is designed as a replaceable component that can be accessed and replaced through a minor surgical procedure without disturbing the transmitter module. This allows the system to recover and reuse the permanently implanted transmitter module while replacing only the consumable battery component, effectively extending system longevity.
3Ease of operation
If the transmitter module thickness is reduced to improve patient comfort, then device comfort increases, but the aperture size for ultrasonic transmission decreases
Solution Approach 1:
The ultrasonic transmission path is optimized by positioning the transmitter module in the pectoral region with the transmitting aperture oriented toward the heart, utilizing the vertical dimension through the chest wall. This spatial arrangement allows for a smaller aperture area while maintaining effective ultrasonic transmission by optimizing the transmission path length and angle through the intervening tissues.
4Reliability
If the device mass is reduced to minimize movement and dislodgement, then device stability improves, but the battery capacity decreases
Solution Approach 1:
The flexible cable connecting the transmitter and battery modules allows the battery module to be positioned at an optimal distance and orientation, distributing the mass load. The cable acts as a mechanical buffer that reduces the constraining effect of the transmitter module on battery placement, enabling a larger battery capacity without directly increasing the mass at the sensitive transmitter implantation site, thereby maintaining device stability.
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
This configuration extends battery life, reduces surgical interventions, enhances patient comfort by minimizing device thickness and weight, and maintains an efficient acoustic transmission path to cardiac tissue, while allowing for battery replacement without disturbing the transmitter module.
Implementation Method 1
This system employs ultrasonic energy transfer from a subcutaneously implantable controller-transmitter device (C-T), which is directed towards one or more receiver-stimulator (R-S) devices implanted at desired sites in the heart
Implementation Method 2
Ultrasonic transducers and circuitry in the R-S convert the transmitted ultrasonic energy into an electrical signal capable of stimulating the cardiac tissue
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A wireless cardiac stimulation device comprising an implantable transmitter module housing a transmitter and a separately implantable battery module housing a battery for powering the transmitter and other device electronics via a subcutaneously routable electrical cable connecting the module is disclosed. The transmitter module contains a transmitter enclosure which comprises one or more ultrasound transducers. Having separate transmitter and battery modules allows implantation of the transmitter module closer to the target receiver implanted in tissue. A discrete battery module also enables easy replacement of the battery without disturbing the transmitter, which is highly desirable.