Subcutaneous Cardiac Defibrillation Lead Electrode Configuration
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Solution Overview
Problem
Subcutaneous implantable cardiac defibrillation systems face challenges in signal-to-noise ratio and energy requirements for effective defibrillation, with subcutaneous electrocardiograms being less sensitive and more prone to noise interference compared to intracardiac electrograms, leading to potential inappropriate shocks and detection inaccuracies.
Innovation Solution
A subcutaneous implantable cardiac defibrillation system with a lead configuration featuring at least three detection electrodes forming specific dipoles, where the first dipole is shorter and positioned closer to the heart, minimizing P and T wave detection and reducing noise interference, combined with a controller for concurrent signal detection and a fixing means to maintain lead position, and optionally including an accelerometer or gyroscope for posture detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If subcutaneous leads are used instead of intracardiac leads, then the risk of systemic infection is eliminated and lead extraction becomes safer, but the signal-to-noise ratio deteriorates and detection accuracy decreases
Solution Approach 1:
The subcutaneous lead is divided into multiple functional segments: a first detection electrode, a second detection electrode, a third detection electrode, and a defibrillation electrode. Each electrode is positioned at specific locations along the lead to capture different aspects of cardiac electrical activity, allowing the system to segment the detection function to improve signal quality while maintaining subcutaneous placement
Solution Approach 2:
The patent introduces spatial dimensionality by positioning electrodes at different locations along the subcutaneous lead trajectory. The first dipole (formed by first and second detection electrodes) and second dipole (formed by third detection electrode and housing) create multiple detection vectors, adding spatial differentiation to the single-lead subcutaneous system to enhance signal discrimination
2Productivity
If subcutaneous leads are used, then venous occlusion is avoided, but the energy required for defibrillation increases
Solution Approach 1:
The defibrillation electrode is positioned between the second detection electrode and the third detection electrode, creating a localized high-energy delivery zone. The housing serves as a return electrode, concentrating the defibrillation current through a specific tissue pathway that optimizes energy delivery efficiency while maintaining subcutaneous lead configuration
Solution Approach 2:
The patent modifies the electrical parameters of the subcutaneous lead system by introducing multiple detection electrodes with specific spacing and configurations. This allows optimization of the detection sensitivity and impedance matching, which indirectly affects the energy requirements for both detection and defibrillation functions
3Quantity of substance
If conventional dipole configurations are used in subcutaneous leads, then P and T waves are detected, but R wave detection becomes difficult and false detections increase
Solution Approach 1:
The patent creates an asymmetric electrode configuration where the first dipole (between first and second detection electrodes) is positioned closer to the heart than the second dipole (between third detection electrode and housing). This asymmetric arrangement optimizes the detection vector for R wave capture while minimizing sensitivity to P and T waves, which have different spatial characteristics
Solution Approach 2:
The controller receives signals from both the first dipole and second dipole and processes them to distinguish R waves from P and T waves. By comparing the timing, amplitude, and morphology of signals from the two dipoles, the system can identify characteristic R wave patterns and filter out non-cardiac noise, reducing false detections
Data Source
AI summary
A cardiac defibrillation system. The system comprising a housing and an implantable lead. The implantable lead comprising two ends, including a first end connected to the housing and a second end being a free end. The implantable lead also comprising a defibrillation electrode and at least three detection electrodes including a first detection electrode, a second detection electrode, and a third detection electrode. The first detection electrode and the second detection electrode forming a first dipole. The third detection electrode and the first detection electrode, or, the third detection electrode and the second detection electrode, or, the housing and one of said detection electrodes, forming a second dipole, where a length of the first dipole is between 5 and 50 millimeters and a length of the second dipole is between 50 and 400 millimeters.