AV Delay Reduction for Cardiac Output Optimization
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Solution Overview
Problem
Current cardiac rhythm management devices, such as pacemakers, often fail to optimize cardiac output in patients with compromised ventricular function, as they either over- or under-load the ventricles due to inadequate atrio-ventricular delay (AVD) settings, leading to inefficient heart contractions and potential complications like pulmonary congestion.
Innovation Solution
An implantable pacing device that intermittently reduces the AVD interval, referred to as the AVDR mode, to either improve cardiac function by reducing ventricular pre-loading or simulate the effects of exercise by inducing asynchronous contractions, using feedback mechanisms to manage pulmonary congestion and adjust pacing based on patient-specific conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the AVD interval is extended to allow complete ventricular filling, then ventricular filling is improved, but ventricular wall stress and pulmonary congestion increase
Solution Approach 1:
The patent implements dynamic adjustment of the AVD interval based on real-time detection of ventricular filling status. The device transitions from a static AVD setting to a dynamic one where the interval is continuously optimized based on sensed physiological parameters, allowing the system to adapt to changing hemodynamic conditions and patient needs.
Solution Approach 2:
The patent employs feedback mechanisms where the pacemaker senses ventricular filling status (through impedance measurements or other physiological sensors) and uses this information to adjust the AVD interval. This closed-loop control system allows the device to respond to actual ventricular loading conditions, reducing wall stress when filling is adequate and preventing pulmonary congestion.
2Stress or pressure
If the AVD interval is shortened to reduce ventricular pre-loading, then ventricular wall stress is reduced, but ventricular filling may become inadequate
Solution Approach 1:
The system dynamically adjusts the AVD interval based on real-time assessment of ventricular filling adequacy. When filling is found to be inadequate, the system extends the AVD to allow more complete filling; when filling is adequate, the system shortens the AVD to reduce wall stress. This dynamic adaptation resolves the contradiction by making the AVD setting responsive to actual physiological needs.
Solution Approach 2:
The patent changes the AVD parameter based on detected physiological states. The device monitors ventricular filling status and adjusts the AVD interval accordingly, transforming a fixed parameter into a variable one that adapts to changing hemodynamic conditions, thus optimizing both filling and wall stress management.
3Reliability
If standard pacing modes are used to treat bradycardia and CRT, then basic rhythm management is achieved, but optimization of cardiac output in patients with compromised ventricular function is insufficient
Solution Approach 1:
The patent applies preliminary action by proactively adjusting the AVD interval before suboptimal ventricular function develops. The system continuously monitors filling status and makes preventive adjustments to optimize cardiac output, rather than waiting for decompensation to occur. This anticipatory approach maintains reliable rhythm management while optimizing productivity.
Solution Approach 2:
The invention transforms static pacing modes into dynamic systems that continuously adapt the AVD interval based on real-time physiological feedback. This dynamic capability allows the system to maintain reliable rhythm management while simultaneously optimizing cardiac output in patients with compromised ventricular function, resolving the contradiction between reliability and productivity.
Data Source
AI summary
An implantable pacing device for delivering ventricular pacing may be configured to intermittently reduce the AVD interval for beneficial effect in patients with compromised ventricular function (e.g., HF patients and post-MI patients). The AVD interval may be reduced in an AVD reduction mode, by shortening the AVD in an atrial triggered ventricular pacing mode or by switching to a non-atrial triggered ventricular pacing mode (e.g., VVI) and delivering paces at a rate above the intrinsic rate. The physiological effects of AVD reduction may be either positive or negative on cardiac output, depending upon the individual patient.