ICD Wavefront Timing Discrimination to Suppress SVT Shocks
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Solution Overview
Problem
Implantable cardioverter defibrillators (ICDs) often deliver unnecessary shocks to patients due to misclassification of supraventricular tachycardia (SVT) as ventricular tachycardia (VT), leading to patient discomfort and health issues, despite their life-saving capabilities.
Innovation Solution
The method involves sensing the direction of electrical wavefront passage through the ventricular region using multiple electrode pairs, particularly along a superior-inferior axis, to differentiate between SVT and VT, thereby preventing inappropriate defibrillation shocks by analyzing the relative timing of wavefront arrival at different ventricular locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ICD delivers defibrillation shocks for all detected tachycardias, then life-saving capability is maintained, but unnecessary shocks are delivered causing patient discomfort and health issues
Solution Approach 1:
The patent segments the tachycardia detection and response process by introducing multiple sensing electrode pairs (at least two pairs positioned at different locations in the ventricular region) to independently detect electrical wavefronts. This segmentation enables differentiation between SVT and VT based on wavefront propagation patterns, allowing the device to deliver therapy only when truly needed (VT detected) while avoiding unnecessary shocks for SVT.
Solution Approach 2:
The patent introduces wavefront propagation direction analysis as an intermediary mechanism between tachycardia detection and shock delivery. By analyzing the direction of electrical wavefront passage through the ventricular region using multiple electrode pairs, the system mediates between detecting tachycardia and delivering therapy, enabling intelligent discrimination that prevents unnecessary shocks while maintaining life-saving capability for true VT cases.
2Measurement precision
If multiple electrode pairs are used to sense wavefront direction, then discrimination accuracy between SVT and VT is improved, but device complexity increases
Solution Approach 1:
The patent applies multi-functionality by using the same implanted heart device to perform both CCM therapy delivery and ICD tachycardia discrimination functions. The electrode pairs serve multiple purposes: they are used for both CCM sensing and for detecting wavefront propagation direction for SVT/VT discrimination. This universal use of existing hardware improves measurement precision without proportionally increasing device complexity.
Solution Approach 2:
The patent enables the implanted device to self-discriminate between SVT and VT using its own sensing capabilities and processing functions. The device uses its internal processors to analyze wavefront propagation patterns from the electrode pairs and automatically make discrimination decisions, eliminating the need for external monitoring or additional complex hardware. The system serves itself by leveraging existing computational resources for the discrimination function.
3Reliability
If wavefront propagation direction is analyzed using multiple electrode pairs, then inappropriate shock delivery is reduced, but processing requirements and algorithm complexity increase
Solution Approach 1:
The patent implements preliminary action by pre-establishing the spatial arrangement and calibration of multiple electrode pairs during device implantation. The system pre-processes and stores information about electrode positions and expected wavefront propagation patterns for normal sinus rhythm. During tachycardia events, the device compares actual wavefront directions against these pre-established references, simplifying real-time processing while maintaining high classification accuracy.
Solution Approach 2:
The patent applies partial action by focusing the wavefront propagation analysis specifically on the ventricular region using strategically positioned electrode pairs. Rather than analyzing the entire heart or using excessive sensing channels, the system concentrates sensing efforts on the critical ventricular region where wavefront direction discrimination is most valuable for SVT/VT differentiation. This targeted approach achieves high reliability without excessive processing complexity.
Data Source
AI summary
During a cardiac arrhythmia, defibrillation shocks from an implanted cardiac defibrillator are suppressed based on the sensing of electrical wavefront arrival times which indicate a supraventricular origin to the cardiac arrhythmia. In some embodiments, times of electrical wavefront arrival in at least two ventricular locations of the heart are sensed; one location being relatively superior, and one relatively inferior (e.g., relatively superior and inferior locations of a ventricular septum). In some embodiments, if the arrival time at the more inferior position is within a predetermined interval after arrival at the more superior position, delivery of defibrillation shocks are suppressed. In some embodiments, additional sensing of electrical wavefront arrival at one or more non-septal ventricular locations is performed, and defibrillation shock suppression is optionally itself suppressed if the additional sensing indicates that the wavefront initiated in a ventricular location.