Page 89 - Biomedical Engineering and Design Handbook Volume 2, Applications

68 MEDICAL DEVICE DESIGN

FIGURE 3.5 A balloon catheter and inflation pump are shown. Balloon catheters are used to widen stenosed
or narrowed vessels and to expand stents. The balloon is often inflated with a mixture of saline and contrast
agent to aid radiographic visualization.

FIGURE 3.6 The stent implantation procedure for a balloon-expandable stent is demonstrated in the
figure. The balloon-mounted stent is first guided into place inside a damaged vessel under fluoroscopy. The balloon
is then inflated, expanding the stent to lie in opposition to the vessel wall. The balloon is then deflated and with-
drawn, leaving the stent in place to prevent constriction of the vessel. (Compliments of Cordis Corporation, Miami
Lakes, FL).

stents have greater flexibility than the slotted tube models, making them attractive for more complex
and difficult to reach lesions such as those found at bifurcations and inside branches (Oesterle et al.,
1998). Some more recent stent designs combine features of slotted tube and coil models. Both stent
types usually undergo further balloon expansion to optimize the resulting placement (Oesterle et al.,
1998). Figure 3.7 illustrates the flexibility that can be achieved by a modern stent.