Dual-Flow LVAD Pumping for Cardiac-Synchronized Pulsatile Flow
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Solution Overview
Problem
Continuous-flow LVADs cause significant side effects due to reduced pulsatility, including increased sympathetic activation, cardiovascular risks, aortic valve issues, gastrointestinal bleeding, and blood pressure measurement challenges, and can lead to malfunction and death.
Innovation Solution
A left ventricular assist device (LVAD) system with a tubular linear motor and control circuitry that provides pulsatile flow synchronized with cardiac cycles, using a magnetic piston and stator to mimic natural heart function, reducing peak power consumption by storing energy during diastole and releasing it during systole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If continuous-flow LVAD is used, then device simplicity is improved, but pulsatility is reduced causing harmful side effects
Solution Approach 1:
The patent employs periodic reciprocating motion of the magnetic piston within the pump chamber to generate pulsatile blood flow. The piston moves back and forth in a periodic cycle, creating pressure variations and flow pulsations that mimic natural cardiac function, thereby resolving the harmful effects of continuous-flow devices while maintaining mechanical simplicity.
Solution Approach 2:
The patent extracts the pulsatility function from the continuous flow by introducing a reciprocating piston mechanism. The piston's periodic movement separates the pumping action into distinct phases (forward and return strokes), creating pulsatile flow patterns while the overall device structure remains relatively simple and integrated.
2Object-affected harmful factors
If pulsatile flow is provided to mimic natural heart function, then organ function is improved, but peak power consumption increases
Solution Approach 1:
The patent applies preliminary action by storing energy in the spring during the piston's return stroke (when less power is needed) and then releasing this stored energy during the forward pumping stroke. This pre-storing of energy during the non-pumping phase reduces the peak power demand during the actual blood ejection phase, while still achieving effective pulsatile flow for organ perfusion.
Solution Approach 2:
The periodic reciprocating motion allows the system to alternate between energy storage (spring compression during return stroke) and energy release (pumping during forward stroke). This periodic energy management smooths power consumption peaks while maintaining the pulsatile flow necessary for normal organ function.
3Object-affected harmful factors
If reciprocating piston is used to create pulsatile flow, then flow pulsatility is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical valve systems with a magnetic piston actuated by electromagnetic forces. Instead of using traditional mechanical components like check valves or complex linkages to create pulsatile flow, the system uses a magnetically driven piston that moves reciprocally within the pump chamber, simplifying the overall mechanical structure while achieving the desired flow pulsatility.
Solution Approach 2:
The spring acts as an intermediary energy storage element between the magnetic piston and the blood flow. The spring mediates the energy transfer by storing energy during the return stroke and releasing it during the pumping stroke, smoothing out power requirements and simplifying the control system while maintaining effective pulsatile flow generation.
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
The LVAD system reduces peak power demands, mimics natural heart function, and provides pulsatile flow crucial for normal organ function, minimizing side effects and enhancing safety.
Implementation Method 1
The magnets are arranged to interact with a magnetic field generated by the coiled wire when current flows therethrough, so as to axially move the reciprocating valve with respect to the stent
Implementation Method 2
The apparatus further includes a spring, adapted to apply a spring force to the piston
Data Source
AI summary
An implantable LVAD system includes an implantable LVAD including an outflow cannula, which is couplable in fluid communication with a circulatory system of the patient at a first site; and an inflow cannula, which is couplable in fluid communication with the circulatory system at a second site upstream of the first site. The LVAD further includes a continuous-flow pump includes a first inlet in fluid communication with the inflow cannula, and a first outlet. The LVAD still further includes a pulsatile-flow pump includes a second inlet in fluid communication with the first outlet of the continuous-flow pump, and a second outlet in fluid communication with the outflow cannula. Control circuitry is configured to activate the continuous-flow pump to provide flow without synchronization with cardiac cycles of a heart of the patient, and activate the pulsatile-flow pump to provide pulsatile flow synchronized with the cardiac cycles. Other embodiments are also described.