Differences in endothelial injury after balloon angioplasty, insertion of balloon-expanded stents or release of self-expanding stents: An electron microscopic experimental study

Purpose: To evaluate which of six different commonly available stents inser ted into an artery without percutaneous transluminal angioplasty (PTA) caus es the least endothelial damage. To compare the degree of endothelial injur y after insertion of such a stent with injury caused by PTA. Methods: Twelve healthy pigs were used in the experiments. In the first par t of the study six different types of stents were inserted into the common iliac arteries. In the second part of the study self-expanding stents with large spaces between the wires were used. PTA was performed in the contrala teral iliac artery. The pigs were killed immediately after the procedure an d resected specimens examined after fixation, using scanning electron micro scopy. Results: All procedures but two were accomplished successfully. More endoth elium was preserved after insertion of self-expanding stents with large spa ces between the wires, compared with stents with small spaces and balloon-e xpanded stents. After insertion of self-expanding stents with large spaces, 50.1% +/- 16.4% of the endothelium remained intact, compared with only 5.6 % +/- 7.7% after PTA. The difference was statistically significant (p < 0.0 01). Conclusion: Self-expanding stents with large spaces between the wires, inse rted without PTA, cause less damage to the endothelium than other stents an d significantly less damage than PTA.