Development of an intravascular fibre optic probe to measure retention of locally delivered drugs following coronary angioplasty

Balloon angioplasty is a technique for dilating stenoses in coronary arteries. It has a high restenosis rate. This may be reduced by delivering drugs locally to the vessel wall where they inhibit the process of restenosis. The authors have developed an intravascular fibre-optic probe to measure how much of a locally delivered fluoresceinated drug is retained in the vessel wall (something there is no established method for doing in vivo) by calculating the ratio between the intensity of fluorescence emitted by the drug to the intensity of radiation supplied to it by an argon laser. Testing in a `simulated artery´ containing fluorescein in its `wall´ demonstrated a relationship between the peak ratio measured by the probe and fluorescein concentration that was linear at low concentrations and logarithmic at high concentrations. Further testing suggested measuring the `area under the curve´ produced by the probe would be a valid method of measuring the total amount of fluorescein present between two points along an artery