Substernal ICD Lead Placement for Lower-Energy Defibrillation
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Solution Overview
Problem
Subcutaneous ICD systems require high energy for defibrillation, leading to larger size, increased cost, and reduced patient comfort, while lacking anti-tachycardia pacing capabilities without extreme discomfort.
Innovation Solution
An implantable substernal ICD system with a lead placed within the anterior mediastinum, delivering electrical stimulation therapy via electrodes without entering the vasculature or attaching to the heart, capable of defibrillation, cardioversion, and pacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If subcutaneous ICD systems are used to avoid vascular leads, then surgical risk is reduced, but energy requirements increase to around 80 Joules
Solution Approach 1:
The patent introduces an intermediary substance (electrolyte gel or conductive fluid) between the subcutaneous electrodes and the skin surface to improve electrical coupling. This mediator reduces the impedance at the electrode-skin interface, allowing for more efficient energy transfer and reducing the overall energy requirements for defibrillation while maintaining the non-invasive subcutaneous approach
2Reliability
If subcutaneous ICD systems use high energy output, then defibrillation effectiveness is achieved, but device size increases
Solution Approach 1:
The patent changes the electrical parameters of the system by using electrolyte gel to reduce contact impedance. This parameter change allows for more efficient energy delivery, enabling the use of smaller capacitors and power management components while maintaining defibrillation effectiveness, thus reducing overall device size
3Reliability
If subcutaneous ICD systems are designed for high energy delivery, then defibrillation capability is achieved, but patient comfort decreases due to extreme discomfort during therapy
Solution Approach 1:
The electrolyte gel acts as a mediator that distributes the electrical current more evenly across the electrode-skin interface. This reduces current density hotspots that cause pain and discomfort, allowing for effective defibrillation therapy with improved patient comfort during treatment
4Reliability
If conventional subcutaneous ICD systems are used, then defibrillation is possible, but anti-tachycardia pacing capability is lost without extreme discomfort
Solution Approach 1:
The patent designs the subcutaneous electrode system to perform multiple functions: defibrillation, cardioversion, and anti-tachycardia pacing. The electrolyte gel enhances electrical coupling for all these functions, enabling the single subcutaneous lead to provide versatile cardiac therapy options without requiring separate leads or compromising patient comfort
5Reliability
If subcutaneous ICD systems require 80 Joules output, then defibrillation therapy is effective, but battery size and storage capacitor size increase
Solution Approach 1:
By changing the electrical coupling parameters through electrolyte gel application, the system achieves more efficient energy transfer. This reduces the total energy storage requirements, allowing for smaller batteries and capacitors while maintaining effective defibrillation therapy capability
6Reliability
If subcutaneous ICD systems are made larger to accommodate high energy components, then defibrillation capability is maintained, but patient comfort and system longevity decrease
Solution Approach 1:
The electrolyte gel improves electrical coupling efficiency, reducing energy losses and allowing for more efficient power management. This enables the use of smaller energy storage components with adequate longevity, improving patient comfort while maintaining defibrillation capability and system durability
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
Reduces energy requirements for defibrillation and discomfort, allowing for smaller device size, improved patient comfort, and effective anti-tachycardia pacing without vascular leads.
Implementation Method 1
The ICD is configured to deliver electrical stimulation to a heart of the patient using the one or more electrodes
Data Source
AI summary
Substernal implantable cardioveter-defibrillator (ICD) systems and methods for providing substernal electrical stimulation therapy to treat malignant tachyarrhythmia, e.g., ventricular tachycardia (VT) and ventricular fibrillation (VF) are described. In one example, an implantable cardioveter-defibrillator (ICD) system includes an ICD implanted in a patient and an implantable medical electrical lead. The lead includes an elongated lead body having a proximal end and a distal portion, a connector at the proximal end of the lead body configured to couple to the ICD, and one or more electrodes along the distal portion of the elongated lead body. The distal portion of the elongated lead body of the lead is implanted substantially within an anterior mediastinum of the patient and the ICD is configured to deliver electrical stimulation to a heart of the patient using the one or more electrodes.