Dynamic Pre-Excitation Interval for Cardiac Resynchronization Therapy

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Solution Overview

Problem

Conventional cardiac resynchronization therapy (CRT) algorithms fail to accurately synchronize left ventricular pacing with the earliest intrinsic right ventricular activation, leading to suboptimal treatment outcomes due to inconsistent placement of the right ventricular lead, which can result in dyssynchrony and reduced effectiveness of fusion pacing.

Innovation Solution

A method and system that adjust the timing of left ventricular pacing by determining an objective estimate of the earliest intrinsic right ventricular activation, applying a correction factor to the pre-excitation interval to ensure precise synchronization with the intrinsic rhythm, thereby optimizing the delivery of pacing pulses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a fixed pre-excitation interval (50-60 ms) is used for LV pacing, then the pacing delivery is simplified and consistent, but the synchronization with the earliest intrinsic RV activation is inaccurate when RV lead placement varies

Engineering Contradiction:

Improvepacing delivery consistencyVSAvoidsynchronization accuracy with earliest RV activation

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The pre-excitation interval is transformed from a fixed value (50-60 ms) to a dynamic, patient-specific value calculated as: (measured RV activation time - desired pre-excitation interval). This allows the pacing system to adapt to varying RV lead positions and individual patient anatomy, achieving accurate synchronization while maintaining operational simplicity through automated calculation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of pre-excitation interval from a conventional fixed range (50-60 ms) to a customized value based on measured RV activation time. By measuring the actual RV activation time (which can be 70-80 ms in late activation cases) and applying the desired pre-excitation interval, the system delivers LV pacing at the optimal time relative to earliest RV activation, improving synchronization accuracy.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If RV lead is placed in electrically late area (e.g., RVOT), then the lead placement is anatomically accessible and stable, but the RV sense time significantly differs from the time of earliest activation

Engineering Contradiction:

Improvelead placement stabilityVSAvoiddelay in RV activation detection

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system measures the actual RV activation time in each patient and uses this feedback to calculate the customized pre-excitation interval. By incorporating the measured RV activation time (而非 assuming 50-60 ms) into the calculation, the system compensates for the time delay inherent in late RV activation sites like RVOT, ensuring LV pacing is delivered at the optimal time relative to earliest RV activation.

Inventive Principle:

Principle #23Feedback

3Ease of manufacture

If LV pacing is delivered using conventional pre-excitation interval calculation, then the pacing protocol is simple to implement, but the pacing stimulus may be delivered after onset of QRS complex which is not ideal for effective capture

Engineering Contradiction:

Improvepacing protocol simplicityVSAvoidpacing timing precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The system performs preliminary measurement of RV activation time before calculating the customized pre-excitation interval. By measuring the actual RV activation time in advance and using it to determine the optimal LV pacing timing, the system ensures that LV pacing is delivered before the onset of the QRS complex (at the desired pre-excitation interval), improving capture effectiveness while maintaining protocol simplicity through automated calculation.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9265955B2Method and system for improved estimation of time of left ventricular pacing with respect to intrinsic right ventricular activation in cardiac resynchronization therapy

Publication Date: 2016.02.23 MEDTRONIC INC

AI summary

A method and system of cardiac pacing is disclosed. A baseline rhythm is determined. The baseline rhythm includes a baseline atrial event and a baseline right ventricular RV event from an implanted cardiac lead or a leadless device, a pre-excitation interval determined from the baseline atrial event and the baseline RV event, and a plurality of activation times determined from a plurality of body-surface electrodes. A determination is made as to whether a time interval measured from an atrial event to a RV event is disparate from another time interval measured from the atrial event to an earliest RV activation time of the plurality of activation times. A correction factor is applied to the pre-excitation interval to obtain a corrected pre-excitation interval in response to determining the RV event is disparate from the earliest RV activation time. The processor is configured to signal the pulse generator to deliver electrical stimuli to a left ventricle (LV) using the corrected pre-excitation interval before RV sensing time.