Cardiac Pacing Mode Switching via Hemodynamic Feedback
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Solution Overview
Problem
Current cardiac prosthesis devices face challenges in maintaining spontaneous ventricular conduction while avoiding the risks associated with prolonged atrioventricular delay (AVD), particularly in patients with sinus dysfunction or during transient conditions like exercise, where a too long AVD can lead to symptoms or arrhythmias.
Innovation Solution
The use of a hemodynamic sensor, such as an endocardial acceleration sensor, to monitor and assess a patient's tolerance to a long AVD, allowing conditional switching between pacing modes to maximize spontaneous conduction while minimizing the risk of symptomatically long AVD, by dynamically adjusting the AVD based on the patient's hemodynamic index and activity level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a long AVD is used to favor spontaneous ventricular conduction, then the occurrence of spontaneous rhythm is increased, but the risk of maintaining symptomatically long AVD increases
Solution Approach 1:
The AVD is made dynamically adjustable based on hemodynamic feedback. The device transitions from a fixed long AVD to a variable AVD that adapts to patient condition, using hemodynamic sensor data to automatically adjust the delay between atrial and ventricular pacing events, thereby optimizing spontaneous conduction while preventing symptomatic bradycardia
Solution Approach 2:
A closed-loop feedback system is implemented where hemodynamic sensors continuously monitor cardiac function and provide real-time information to the pacing device. This feedback enables the device to detect when the long AVD becomes symptomatic and automatically adjust the AVD or switch pacing modes to maintain optimal hemodynamic function
Solution Approach 3:
The device autonomously monitors its own performance through integrated hemodynamic sensors and automatically adjusts pacing parameters without external intervention. The system self-regulates the AVD based on real-time hemodynamic assessment, eliminating the need for manual programming adjustments when symptomatic long AVD occurs
2Reliability
If AVD hysteresis algorithm is used to extend AVD under certain criteria, then spontaneous rhythm occurrence is favored, but the technique is of limited use in patients with sinus dysfunction
Solution Approach 1:
The traditional rate-based hysteresis algorithm is replaced with a hemodynamic-based control system. Instead of using purely temporal criteria (heart rate thresholds), the system uses physiological feedback from hemodynamic sensors to determine when to extend AVD, making the algorithm adaptable to various patient conditions including sinus dysfunction where rate-based criteria fail
Solution Approach 2:
The control parameters for AVD adjustment are changed from fixed rate-based thresholds to dynamic hemodynamic parameters. The system monitors actual cardiac function through hemodynamic sensors and adjusts AVD based on measured physiological state rather than predetermined rate criteria, thereby expanding applicability to patients with sinus dysfunction and other conduction abnormalities
3Reliability
If a fixed long AVD is programmed to preserve intrinsic conduction, then ventricular pacing is reduced, but the device cannot respond to transient conditions like exercise
Solution Approach 1:
The AVD transitions from a fixed programmed value to a dynamic parameter that automatically adjusts based on real-time hemodynamic conditions. During exercise or other transient states, the hemodynamic sensor detects changes in cardiac function and the device responds by shortening the AVD or switching to DDD mode, ensuring adequate cardiac output while preserving intrinsic conduction during rest
Data Source
AI summary
Devices and methods for providing pacing in multiple modes are provided. One device operates in a dual chamber (DDD or biventricular) mode and in a pacing mode favoring the spontaneous atrioventricular conduction such as an AAI mode (10) with a ventricular sensing or a mode with hysteresis of the atrioventricular delay. The device controls (10-18) the conditional switching from one mode to the other. The device comprises a hemodynamic sensor, including an endocardial acceleration sensor, derives a hemodynamic index representative of the hemodynamic tolerance of the patient to the spontaneous atrioventricular conduction. The device controls inhibiting or (20) forcing the conditional switching of the device to the DDD (or biventricular) mode according to the evolution of the hemodynamic index.