Abstract
The biodegradable poly (L-lactic acid) (PLLA) stents, made of a cylindrical knitted structure of PLLA monofilament, were implanted into the coronary arteries of 8 pigs by 8 Fr guiding catheters. Follow-up coronary angiography was performed and the standard optical microscopic observations of the cross section of the stented segments were carried out after implantation.
Coronary angiographies and the histological examinations revealed that no acute closure was observed immediately after implantation and the patency of stented arteries of PLLA stent segments was wider. The %stenosis was lower than any other biodegradable stents already reported. These results are attributable to the lower degradation rate of PLLA which keeps its strength of the stent to hold the arteries from the inside for a longer period of time.
It was further observed that the overlapping portions of the knitted structure tend to press and injure the internal wall of the blood vessel resulting in the growth of neo-intimal hyperplasia. The modified PLLA stents whose overlapping portions were flattened by compression at higher temperature give less %stenosis.
