Figure 5-3 X-ray detectability of stent: (a) intraoperative angiography of porcine coronary artery implanted with Zn Cu stent (white circle highlights the position of stent); (b) Angiography 18 months after implantation of Zn Cu stent in porcine coronary artery (white circle highlights the position of stent); (c) Intraoperative coronary angiography of pigs implanted with 316L SS stent (white circle highlights the position of the stent); (d) Intraoperative angiography of common carotid artery in New Zealand white rabbits implanted with magnesium based stent [23] (the radiopaque mark on the balloon is highlighted with a yellow circle to help locate the stent)
The X-ray detectability of materials mainly depends on their material density and electron density. The electron density of zinc is higher than that of magnesium, iron or polymer, so it has advantages in degradable scaffolds. Figure 5-3 (a) shows the Zn Cu stent in porcine coronary artery during the operation: the zinc copper stent is clearly developed under X-ray, the stent rod is fully expanded, and the shape is ideal after stent filling. Compared with FIG. 5-3 (c), the development of zinc copper alloy stent under X-ray is equivalent to that of traditional stent (316L SS stent), indicating that it can meet the development requirements of clinical operation. In contrast, almost no stent morphology was seen in 5-3 (d) magnesium stent angiography images. The positioning of magnesium stent depends on the radiopaque mark on the balloon. These markers, together with radiopaque iodized contrast agents, can also achieve the precise placement of stents in the artery. However, this development method cannot meet the requirements of post expansion adjustment after stent implantation [24].
Figure 5-3 (b) shows the X-ray image of the blood vessels in the implanted section of Zn Cu stent 18 months after implantation: at this time, it is difficult to find the Zn Cu stent under X-ray, indicating that the Zn Cu stent has been degraded and the density has decreased.
