Plethysmography-Based Hemodynamic Optimization for Pacemakers

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Solution Overview

Problem

Current methods for optimizing hemodynamic performance during cardiac resynchronization therapy (CRT) are invasive, unreliable, and cumbersome, lacking a simple and reliable clinical tool for monitoring and optimizing hemodynamics.

Innovation Solution

The use of time delays between electrical activity signals of the heart and plethysmography signals indicative of arterial blood volume changes to select optimal pacing sites and parameter sets for implantable medical devices, ensuring sufficient cardiac stroke volume through non-invasive or minimally invasive means.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If Millar blood pressure sensor is used for hemodynamic measurement, then measurement accuracy is improved, but device invasiveness and procedural risk increase

Engineering Contradiction:

Improvehemodynamic measurement accuracyVSAvoidprocedural risk and invasiveness

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical Millar blood pressure sensor with an optical detection system using photoplethysmography (PPG). The PPG sensor uses light absorption changes in blood to detect hemodynamic parameters non-invasively, eliminating the need for invasive catheter insertion while maintaining measurement capability through optical-biological interaction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces photodetectors and light sources as intermediary components that indirectly measure hemodynamic parameters through optical signals transmitted through tissue. This intermediary optical measurement system avoids direct mechanical contact with blood vessels, reducing procedural risk while providing sufficient hemodynamic information for CRT optimization.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If echocardiography is used for hemodynamic monitoring, then non-invasive measurement is achieved, but measurement reliability and procedural efficiency deteriorate

Engineering Contradiction:

Improvenon-invasive measurementVSAvoidhemodynamic measurement reliability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent replaces ultrasound-based echocardiography with optical photoplethysmography for hemodynamic monitoring. The PPG system uses light interaction with blood volume changes to provide non-invasive measurements with improved reliability for CRT optimization, eliminating ultrasound artifacts and operator dependency while maintaining non-invasive benefits.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If traditional hemodynamic optimization methods are used, then measurement capability is improved, but device complexity and procedural time increase

Engineering Contradiction:

Improvehemodynamic monitoring capabilityVSAvoidprocedural complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent integrates photoplethysmography sensing capabilities directly into the implantable pulse generator (IPG), allowing the same device to perform both pacing functions and hemodynamic monitoring. This multi-functionality eliminates the need for separate specialized sensors and reduces procedural complexity while maintaining comprehensive hemodynamic optimization capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the PPG optical sensing system with the existing pacing lead and IPG infrastructure. By merging hemodynamic monitoring functions into the already-implanted pacing system, the patent avoids additional invasive procedures and reduces overall procedural complexity while providing accurate stroke volume measurement for CRT optimization.

Inventive Principle:

Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for the selection of optimal pacing sites and parameter sets that enhance cardiac stroke volume, providing a reliable and efficient method for optimizing hemodynamic performance during CRT, reducing the need for invasive procedures and improving patient outcomes.

Implementation Method 1

a plethysmograph signal indicative of changes in arterial blood volume is obtained using a photodetector

Methodology Applied

Scientific EffectPhotoplethysmography: Absorption (EM radiation)

Data Source

PatentUS8914108B2Method for hemodynamic optimization using plethysmography

Publication Date: 2014.12.16 PACESETTER INC

AI summary

Time delays between a feature of a signal indicative of electrical activity of a patient's heart and a feature of a plethysmograph signal indicative of changes in arterial blood volume are used to arrange the operation of an implantable device, such as a pacemaker. Shorter time delays between the feature of the signal indicative of electrical activity of a patient's heart and the feature of the plethysmograph signal indicative of changes in arterial blood volume are indicative of larger cardiac stroke volumes. The time delay can be used to select a pacing site or combination of pacing sites and/or to select a pacing interval set.