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An intramyocardial catheter for repeated in vivo sampling of interstitial fluid
John P Tessmer1, Paul S Pagel, Dorothee Weihrauch
1Department of Anesthesiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
Insights
A novel catheter allows chronic in vivo sampling of myocardial interstitial fluid. This method aids in identifying mitogenic factors crucial for coronary collateral development in response to ischemia.
Area of Science:
- Cardiovascular Research
- Biomedical Engineering
Background:
- Coronary collateral development is a key adaptation to chronic myocardial ischemia.
- Identifying mitogenic factors driving collateral formation is challenging due to sampling difficulties.
Purpose of the Study:
- To develop and evaluate a novel catheter for chronic in vivo sampling of myocardial interstitial fluid.
- To facilitate the identification of factors involved in coronary collateral development.
Main Methods:
- An exchange catheter was implanted in the left ventricular myocardium of dogs.
- Repetitive, brief coronary occlusions stimulated collateral growth.
- Myocardial interstitial fluid was collected daily and tested for mitogenic activity.
Main Results:
- The implanted catheter functioned effectively without complications.
- Interstitial fluid collected via the catheter induced significant proliferation of vascular smooth muscle and endothelial cells in vitro.
Conclusions:
- The developed exchange catheter enables sustained in vivo sampling of myocardial interstitial fluid.
- This technique shows promise for identifying mitogens essential for coronary collateral growth.
Introduction:
Coronary collateral development is an important adaptive response to chronic myocardial ischemia. Characterization of mitogenic factors responsible for collateral formation has been an elusive goal because these substances are difficult to sample from the myocardial interstitium at multiple times. We report the implantation of an exchange catheter capable of in vivo sampling of myocardial interstitial fluid in chronically instrumented dogs.
Methods:
The catheter consisted of multiple perforations within a 2-cm segment of Micro-Renathane tubing that was implanted into the left ventricular myocardium between the left anterior descending (LAD) and left circumflex coronary artery (LCCA) perfusion territories and secured to the epicardium with a Silastic disk. Dogs (n=5) underwent brief (2 min) LAD occlusions once per hour, 8 times/day, 7 days/week for 2 weeks to stimulate coronary collateral growth. Another group of dogs (n=6) without repetitive coronary occlusions served as controls. Myocardial interstitial fluid was collected daily, and mitogenic activity was evaluated by the proliferative responses of growth-arrested, cultured vascular smooth muscle and endothelial cells.
Results:
All dogs tolerated catheter implantation without complication. Each catheter functioned well throughout the duration of the experiment. Myocardial interstitial fluid obtained using the exchange catheter in this model of repetitive coronary occlusion produced marked proliferation of vascular smooth muscle and endothelial cells in vitro.
Discussion:
The exchange catheter enables chronic in vivo sampling of myocardial interstitial fluid and may facilitate identification of mitogens involved in coronary collateral development.