Implantable Pacing Device Using Heart Sound Timing

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Solution Overview

Problem

Existing cardiac pacing systems face challenges in maintaining optimal atrio-ventricular pacing delays due to variations in cardiac and device function over time, leading to transient benefits from optimizations.

Innovation Solution

An implantable medical device system that measures intra-atrial conduction intervals and first heart sounds to calculate an S1-conduction lag, adjusting atrial-ventricular pacing delays to ensure pacing occurs after the end of the intra-atrial conduction interval and before mitral valve closure, switching between biventricular and univentricular pacing therapies based on heart sound timing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If AV delay is optimized at implantation and re-optimized during follow-up, then cardiac performance is improved, but the benefits are not long lasting due to changes in device and cardiac function

Engineering Contradiction:

Improvelongevity of pacing therapy effectivenessVSAvoidability to adapt to changing cardiac function

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system dynamically adjusts the AV delay parameter in real-time based on continuously monitored heart sound timing and intra-atrial conduction intervals. The AV delay is modified according to the formula: AV delay = IACI-LVPROX + % * ΔS1_C, where ΔS1_C represents the S1-conduction lag. This dynamic adaptation ensures the pacing therapy remains optimal as cardiac function changes over time, resolving the contradiction between maintaining reliable long-term effectiveness and adapting to changing physiological conditions.

Inventive Principle:

Principle #15Dynamics

2Reliability

If pacing is delivered based on fixed AV delay, then device operation is simple, but pacing may occur before mitral valve closure causing undesired effects

Engineering Contradiction:

Improvesafety of pacing deliveryVSAvoidcomplexity of AV delay calculation

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system employs feedback mechanisms by continuously monitoring the timing of the first heart sound S1 and intra-atrial conduction interval IACI-LVPROX, then using this information to adjust the AV delay parameter. The feedback loop ensures pacing is delivered at the optimal moment after mitral valve closure by calculating the S1-conduction lag ΔS1_C and modifying the AV delay accordingly. This feedback-based approach enhances safety while managing complexity through automated calculations.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces fixed mechanical timing parameters with a dynamic calculation system that uses acoustic sensing (heart sounds) and electrical conduction measurements. Instead of relying on predetermined fixed AV delays, the system substitutes a computational approach that automatically calculates the optimal timing based on real-time physiological feedback, thereby improving safety without requiring manual intervention.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If rate adaptive adjustment of PR and AR delays is implemented, then pacing therapy responds to activity level, but opportunities remain to improve mechanisms for adjusting rate adaptive therapies

Engineering Contradiction:

Improverate adaptability of pacing therapyVSAvoidoptimality of AV delay at different rates

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system performs preliminary measurement and calculation of the intra-atrial conduction interval IACI-LVPROX and S1-conduction lag ΔS1_C across different heart rates and activity levels. By pre-characterizing the relationship between heart rate and conduction timing, the system establishes a foundation for optimal AV delay selection at any given rate. This preliminary action enables reliable rate-adaptive pacing by having the optimal timing parameters ready before pacing is delivered at different activity levels.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10668289B2Method and device for controlling rate adaptive pacing based on heart sounds

Publication Date: 2020.06.02 PACESETTER INC

AI summary

A method and system are provided for controlling an adaptive pacing therapy using an implantable medical device (IMD). The method provides electrodes that are configured to be located proximate to an atrial (A) site, left ventricular (LV) site and right ventricular (RV) site of the heart. The method utilizes one or more processors to perform obtaining an intra-atrial conduction interval (IACI-LVPROX) between an atrial event and intrinsic conduction at an LV site that is proximal to a sinoatrial (SA) node and obtaining timing of a first heart sound S1. The processors determine whether the S1 occurs after the IACI-LVPROX, and calculates an S1-conduction lag ΔS1_C between the IACI-LVPROX and the first heart sound S1. The processors set an atrial-ventricular pacing (AV) delay based on the IACI-LVPROX and the ΔS1_C. The processors deliver a pacing therapy based on the AV delay.