An intramyocardial catheter for repeated in vivo sampling of interstitial fluid.

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.