Epicardial Microdialysis Probe for Cardiac Metabolic Sampling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current microdialysis techniques for sampling vital organs, such as the heart, face challenges including tissue damage, prolonged equilibration times, and instability due to organ movement, which hinder efficient monitoring of metabolic changes.
Innovation Solution
A microdialysis probe is designed to be temporarily attached to the surface of vital organs using sutures, featuring a semi-permeable membrane and a U-shaped channel for perfusion fluid flow, allowing sampling without insertion into the organ's substance, thus minimizing tissue damage and reducing equilibration time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a microdialysis catheter is inserted into the substance of an organ (e.g., heart wall), then reliable sampling of metabolic substances can be obtained, but tissue damage occurs and prolonged equilibration time (60-90 minutes) is required
Solution Approach 1:
The invention inverts the traditional insertion approach by placing the catheter on the external surface of the organ rather than inserting it into the substance. The catheter is positioned on the epicardial surface of the heart with the semi-permeable membrane in direct contact with the organ surface, allowing sampling without penetration and thereby eliminating tissue damage while maintaining sampling reliability
Solution Approach 2:
The invention transitions from a three-dimensional insertion approach (inserting the catheter into the organ substance) to a two-dimensional surface approach (placing the catheter on the organ surface). This dimensional change allows the semi-permeable membrane to sample metabolic substances through the organ surface without requiring deep insertion, thus avoiding tissue damage while maintaining measurement precision
2Measurement precision
If a microdialysis catheter is inserted into the substance of an organ, then metabolic sampling can be performed, but a prolonged equilibration period of 60-90 minutes is required before reliable data can be obtained
Solution Approach 1:
The invention performs preliminary action by placing the catheter on the organ surface before any sampling begins, with the semi-permeable membrane already in optimal contact with the tissue. This pre-positioning eliminates the need for prolonged equilibration time that would otherwise be required to establish proper sampling conditions after insertion, allowing reliable data to be obtained immediately
Solution Approach 2:
The invention extracts the catheter from the organ substance and repositions it on the external surface, removing the source of the problem (insertion trauma and fluid accumulation) while preserving the essential sampling function. This extraction eliminates the need for lengthy equilibration periods required to resolve insertion-related complications
3Speed
If a microdialysis probe is placed in a beating heart, then rapid metabolic response can be measured, but the catheter position can be disturbed by heart contractions and damage to heart tissue and catheter can occur
Solution Approach 1:
The invention inverts the placement strategy by positioning the catheter on the external surface of the beating heart rather than inserting it into the myocardium. This external placement allows the catheter to remain stable despite heart contractions, as the flexible catheter can accommodate the beating motion without dislodgement or tissue damage, while still enabling rapid metabolic response measurement through the semi-permeable membrane in contact with the heart surface
Solution Approach 2:
The invention employs a flexible catheter design that can accommodate the dynamic motion of the beating heart. The flexible material allows the catheter to move with the heart contractions without compromising position stability or causing tissue damage, maintaining both the rapid metabolic response capability and the reliability of catheter positioning
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 enables rapid and reliable measurement of metabolic changes with reduced tissue damage and eliminates the need for lengthy equilibration, facilitating more effective clinical applications, especially during cardiac surgery.
Implementation Method 1
Sample collection is based on passive diffusion through a semi-permeable membrane placed at the end of a catheter
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The microdialysis technique and device of the present invention can be used to study metabolic aspects of human and animal organs. When a microdialysis catheter is for example placed into the substance of a beating heart, there is always concern for problems with the catheter position. Further, there is always a risk for damage to heart tissue as well as to the catheter. The present invention is designed to avoid such damages, and a study has confirmed that data obtained from the epicardial probe of the present invention reflects the state of the myocardial metabolism. In anesthetized normoventilated pigs (n=20), a sternotomy was performed and a Gore-tex suture snare was placed around a branch of the left anterior descending (LAD) artery. One microdialysis probe was inserted in the myocardial tissue supplied by the snared LAD branch. Another microdialysis probe was placed on the epicardial surface above the myocardial probe. The protocol included four, ten minute ischemic periods (intervention group) followed by a forty minute ischemic period. The control group was only exposed to a forty minute ischemic period. It was possible to place the microdialysis probes of the present invention on the epicardial surface, and to recover samples reflecting the myocardial metabolic state of the heart. It was also possible to measure rapid changes in concentrations especially for lactate, where ischemia periods as short as ten minutes resulted in detectable increases. A similar pattern was found when analysing glucose and glycerol concentrations in paired samples. Data obtained from the device and method of the present invention, placed on the epicardial surface showed a similar pattern compared to data from a standard probe placed in the myocardium. Thus, the epicedial application of the present invention is useful for perioperative monitoring during cardiac surgery.