Sub-threshold Biphasic Cardiac Stimulation for Conduction Delays

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Solution Overview

Problem

Heart failure patients often experience conduction delays in electrical impulses to the ventricles, leading to inefficient heart pumping due to asynchronous contractions of the left and right ventricles, which existing pacemaker technologies fail to adequately address, especially with the limitations of anodal current use and battery longevity.

Innovation Solution

A system and method employing sub-threshold biphasic stimulation, using a combination of anodal and cathodal pulses to strengthen heart contractions, where sensors monitor heart activity and adjust the waveform amplitude and application based on contraction strength, ensuring improved conduction and contractility without increasing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional pacemakers use cathodal or anodal current to stimulate the myocardium, then the heart can be paced, but the stimulation threshold is high and battery life is limited

Engineering Contradiction:

Improveheart pacing effectivenessVSAvoidbattery consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The stimulation pulse is divided into two phases: a first phase (cathodal or anodal) and a second phase (opposite polarity). This segmentation allows the first phase to initiate depolarization at sub-threshold levels and the second phase to complete the depolarization, reducing overall energy requirements while maintaining effective pacing

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first phase of the biphasic pulse performs preliminary action by initiating membrane depolarization before the second phase completes the process. This preliminary depolarization reduces the energy needed in the second phase, lowering the overall stimulation threshold and extending battery life

Inventive Principle:

Principle #10Preliminary action

2Reliability

If anodal current is used to stimulate the myocardium, then the stimulation threshold is reduced, but the risk of arrhythmogenesis increases

Engineering Contradiction:

Improvecontraction strengthVSAvoidarrhythmogenesis risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the polarity parameter of the stimulation pulse by using a biphasic waveform where the first phase can be anodal (reducing threshold) and the second phase is cathodal (safety phase). This parameter change allows exploitation of anodal current's low threshold benefit while the subsequent cathodal phase prevents arrhythmogenic effects

Inventive Principle:

Principle #35Parameter changes

3Reliability

If higher current is used to overcome conduction delays, then ventricular activation is improved, but power consumption increases

Engineering Contradiction:

Improveventricular conductionVSAvoidpacemaker power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The pacemaker dynamically adjusts the amplitude and duration of the biphasic pulse phases based on sensed cardiac conditions. For patients with conduction delays, the system can optimize the first phase to provide sufficient depolarization while the second phase completes activation, achieving reliable ventricular conduction at lower overall power consumption than traditional monophasic high-current approaches

Inventive Principle:

Principle #15Dynamics

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 enhances cardiac contraction efficiency, improves blood flow, and prolongs pacemaker battery life by using sub-threshold biphasic waveforms to strengthen atrial and ventricular contractions, addressing conduction delays and reducing power consumption.

Implementation Method 1

The effect of anodal current is to hyperpolarize the resting membrane. On sudden termination of the anodal pulse, the membrane potential returns towards resting level, overshoots to threshold, and a propagated response occurs.

Methodology Applied

Scientific EffectAnodal current hyperpolarization: Capacitance

Implementation Method 2

Cathodal current comprises electrical pulses of negative polarity. This type of current depolarizes the cell membrane by discharging the membrane capacitor, and directly reduces the membrane potential toward threshold level.

Methodology Applied

Scientific EffectCathodal current depolarization: Capacitance

Data Source

PatentUS9610446B2System and method for stimulating the heart using sub-threshold biphasic stimulation

Publication Date: 2017.04.04 ROCKY MOUNTAIN BIPHASIC INC

AI summary

A rules engine acquires sensor data from sensors applied to the heart and determines whether an electrical waveform should be applied to the heart and, if so, the type of electrical waveform. A multiphase cardiac stimulus generator generates waveforms in response to the rules engine. The electrical waveform is applied to one or more electrodes implanted in or on the heart.