Pressure-Unloading LVAD Counterpulsation for Native Ventricular Function
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Solution Overview
Problem
Clinically available left ventricular assist devices (LVADs) severely depress native left ventricular function by unloading the heart, compromising recovery and promoting fibrosis, while lacking pulsatility, which is crucial for myocardial recovery.
Innovation Solution
A novel implantable counterpulsation LVAD with a rigid housing and elastomeric membrane, oriented to provide ventricular unloading and pulsatility, eliminating the need for heart-lung bypass and using a driveline for gas and sensor conduits to sense heart rhythm, allowing for partial unloading and pulsatile flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If clinically available LVADs are used to provide ventricular unloading, then cardiac output is improved, but native left ventricular function is severely depressed
Solution Approach 1:
The patent inverts the conventional LVAD approach by using counterpulsation technology that augments native ventricular function rather than bypassing it. The device inflates during diastole to reduce afterload and deflates during systole to augment ejection, working in synergy with the native heart to maintain ventricular function while improving cardiac output.
Solution Approach 2:
The device employs periodic counterpulsation cycles synchronized with the cardiac cycle, inflating and deflating the elastomeric membrane in rhythm with heartbeats. This periodic action provides pulsatile flow that mimics natural cardiac function, improving cardiac output while preserving native ventricular mechanics.
2Device complexity
If continuous-flow LVADs are used, then device simplicity is improved, but pulsatility is lost which is crucial for myocardial recovery
Solution Approach 1:
The device transforms continuous gas flow into periodic blood flow through the rhythmic inflation and deflation of the elastomeric membrane. This periodic action generates physiological pulsatility that promotes myocardial recovery while maintaining relatively simple device architecture using off-the-shelf components.
3Productivity
If profound ventricular unloading is achieved, then cardiac output is improved, but fibrosis is promoted and recovery potential is compromised
Solution Approach 1:
Rather than unloading the ventricle by bypassing it, the device augments native ventricular function through counterpulsation. This approach reduces afterload during diastole and augments ejection during systole, improving cardiac output while maintaining physiological ventricular mechanics that prevent fibrosis.
Solution Approach 2:
The device converts the harmful effect of high afterload into a beneficial therapeutic effect. By inflating during diastole, the device actively reduces afterload, transforming the pathological burden on the failing heart into a therapeutic intervention that improves function without causing fibrosis.
4Reliability
If complex surgical procedures with heart-lung bypass are used, then implantation safety is improved, but surgical complexity and risk are increased
Solution Approach 1:
The device enables implantation without requiring heart-lung bypass or complex cardiopulmonary support systems. The counterpulsation mechanism provides sufficient hemodynamic support during implantation to allow the procedure to proceed using standard surgical techniques, making the system self-sufficient for the implantation process.
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 device preserves native left ventricular function, promotes myocardial recovery, reduces thrombus formation risk, and simplifies surgery by eliminating heart-lung bypass, enabling safer implantation and weaning from support.
Implementation Method 1
a movable elastomeric membrane into an air sub-chamber
Implementation Method 2
an air sub-chamber which is connectible through a drive line to an external pneumatic source
Data Source
Figure 1~2
Figure 3
Figure 4~8
AI summary
An implantable pump includes a rigid housing with an oblate spheroid shape and having an inner chamber divided by a movable elastomeric membrane into a gas sub-chamber which is connectible through a drive line to an external pneumatic source, and a blood sub-chamber which is connectible through a graft assembly to an anatomical heart. The housing includes a blood port opening oriented at an angle and at the upper apex of the housing and connected to the blood sub-chamber, and a gas port opening to the gas sub-chamber that is situated at a lower apex of the housing. The pump is provided with a drive line that includes a gas conduit and a heart sensor, the drive line connectible to a drive system that is capable of delivering gas flow through the drive line gas conduit in response to signals driven by the heart sensor.