Rotational Blood Pump Control via Pulsatility Index Gradient

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Solution Overview

Problem

Rotary blood pumps used as left ventricular assist devices often operate at constant rotational speed, leading to hazards such as ventricular collapse and excessive suction, and lack adaptability to varying physiological conditions, necessitating a control method that adjusts the operating point optimally without physician intervention.

Innovation Solution

A rotational blood pump with a control system that calculates and regulates the pulsatility index (PI) and its gradient with respect to rotational speed (GPI) to maintain a pre-defined set-point, allowing for adaptive operation between full and partial assist modes, thereby avoiding suction and optimizing ventricular washout.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the pump operates at constant rotational speed to simplify control, then device complexity is reduced, but adaptability to varying physiological conditions deteriorates

Engineering Contradiction:

Improvecontrol system complexityVSAvoidadaptability to physiological conditions

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The pump system performs self-regulation by automatically calculating the pulsatility index from measured pressure differences and autonomously adjusting rotational speed to maintain optimal PI values, eliminating the need for external physician intervention and adapting to changing physiological conditions in real-time

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The control system continuously measures pressure difference across the pump, calculates pulsatility index, and uses this feedback to adjust rotational speed, creating a closed-loop control system that adapts to varying physiological conditions while maintaining optimal performance

Inventive Principle:

Principle #23Feedback

2Productivity

If the pump operates at maximum flow rate to improve productivity, then flow rate is increased, but harmful factors increase due to ventricular collapse and excessive suction

Engineering Contradiction:

Improveflow rateVSAvoidventricular collapse and suction

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The control system monitors pressure difference across the pump and calculates pulsatility index as feedback, using this information to adjust rotational speed and avoid operating conditions that cause ventricular collapse and excessive suction while maintaining optimal flow rate

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically changes the operational parameter (rotational speed) based on calculated pulsatility index values, adjusting speed to maintain PI within optimal ranges that prevent ventricular collapse and excessive suction while maximizing flow rate

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the pump operates at maximum flow rate with closed aortic valve to maximize support, then flow rate is improved, but reliability deteriorates due to thrombus formation risk

Engineering Contradiction:

Improveflow rateVSAvoidthrombus formation risk

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system dynamically adjusts rotational speed to maintain pulsatility index within optimal ranges that promote adequate ventricular washout and prevent stasis, thereby reducing thrombus formation risk while maintaining effective flow rate

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The control system uses pulsatility index calculated from pressure measurements as feedback to regulate rotational speed, ensuring operating conditions that maintain adequate ventricular emptying and reduce stasis-related thrombus formation

Inventive Principle:

Principle #23Feedback

4Device complexity

If the pump operates at constant speed to reduce control complexity, then device complexity is reduced, but loss of information about optimal operating point increases

Engineering Contradiction:

Improvecontrol system complexityVSAvoidoptimal operating point information

Core Design Contradiction:

Device complexityVSLoss of information

Solution Approach 1:

The pump system autonomously determines the optimal operating point by calculating pulsatility index from measured pressure differences and automatically adjusting rotational speed to maintain optimal PI, eliminating the need for external physician intervention and continuous monitoring

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The control system continuously measures pressure difference, calculates pulsatility index, and uses this feedback information to automatically adjust rotational speed, maintaining optimal operating conditions without requiring external intervention or loss of critical operating information

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9352077B2Rotational pump and methods for controlling rotational pumps

Publication Date: 2016.05.31 BERLIN HEART GMBH

AI summary

A rotational pump capable of running at a rotational speed (n) having a system for direct or indirect measurement of pressure difference or flow rate across the pump, wherein a control system is designed to calculate an index of pulsatility (PI) of the pressure difference or flow rate, estimating the gradient of PI with respect to the rotational speed (dPI/dn) and regulating the dPI/dn to a pre-defined set-point or regulating the pump in a way that the dPI/dn is minimal.