Cardiac Pacing Mode Switching for A-V Block Detection
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Solution Overview
Problem
Dual chamber cardiac function management devices often perform unnecessary ventricular pacing, increasing the risk of heart failure and atrial fibrillation due to fixed or dynamic AV delays, which can lead to inefficient heart chamber contraction coordination.
Innovation Solution
A cardiac device with a cardiac contraction sensing circuit, timer circuit, and controller that detects A-V block events over multiple cardiac cycles, switching between primary and secondary pacing modes to adjust ventricular pacing based on A-A and V-V intervals, reducing unnecessary ventricular pacing by promoting intrinsic AV conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If dual chamber CFM device provides pacing to both atrium and ventricle with fixed or dynamic AV delays, then coordination of heart chamber activity is improved, but unnecessary ventricular pacing increases leading to higher risk of heart failure and atrial fibrillation
Solution Approach 1:
The patent implements dynamic pacing mode switching between DDD and AAI/AAIR modes based on real-time detection of A-V block events. The device transitions from a fixed dual-chamber pacing mode to a dynamic mode that adapts to the patient's conduction status, reducing unnecessary ventricular pacing when A-V block is detected while maintaining coordinated chamber activity when conduction is normal
Solution Approach 2:
The patent changes the pacing mode parameter from fixed DDD to variable modes (DDD, AAI, or AAI with VVI backup) based on detected A-V block events. By monitoring A-V intervals and switching pacing modes in response to conduction abnormalities, the device optimizes ventricular pacing necessity while preserving atrial-ventricular coordination when appropriate
2Reliability
If device switches pacing mode frequently in response to intermittent A-V block, then response to conduction abnormalities is improved, but pacing mode stability deteriorates
Solution Approach 1:
The patent implements a requirement for multiple consecutive A-V block events before triggering a pacing mode switch. This preliminary action threshold prevents premature mode changes due to transient conduction variations, ensuring that mode switching occurs only when sustained A-V block is confirmed, thereby maintaining pacing stability while still responding reliably to true conduction abnormalities
Solution Approach 2:
The patent uses a counter mechanism that requires a specified number of consecutive A-V block events (e.g., 3 out of 5) before initiating mode switch. This cushioning approach protects against premature mode switching by buffering transient conduction variations, ensuring mode stability while maintaining reliable detection of sustained A-V block conditions
Data Source
AI summary
A device comprises a cardiac contraction sensing circuit, a timer circuit, an electrical stimulation circuit, and a controller. The timer circuit provides a time duration of an atrial-atrial interval between successive atrial contractions, a ventricular-ventricular interval between successive ventricular contractions, and an atrial-ventricular (A-V) interval between an atrial contraction and a same cardiac cycle ventricular contraction. The controller includes an event detection module and a pacing module. The event detection module is configured for determining whether A-V block events are sustained over multiple cardiac cycles. The pacing module is configured for providing pacing therapy according to a primary pacing mode that includes AAI(R) mode with non-tracking VVI backup mode, and for switching the pacing therapy to a secondary tracking pacing mode if A-V block events are sustained over multiple cardiac cycles.