Introduction - Microsurgery: Advances, Simulations, and Applications - page 5

the state of the ischemia of the myocardium. Moreover, when
arteriosclerosis produces complete occlusion of coronary artery
by thrombus growth or detachment, it is necessary to restart the
blood stream promptly for avoiding brain damage due to the cardiac
infarction condition. The lack of blood low in the myocardium results
in its necrosis when this state remains for a long time; therefore it is
necessary to expand the narrowed area as soon as possible. Usually
this dilation is achieved by the expansion of a balloon catheter. The
balloon located in the balloon-catheter tip has originally the same
diameter as the catheter body; after the balloon is led into the
affected part, it is dilated by injecting physiological saline. However,
the dilated vessel might return to the original size again, therefore
a cylindrical metallic self-expandable mesh called stent is placed to
keep the blood vessel dilated.

1.1.1.3 Trans-catheter aortic valve implantation

Recent artiicial heart valves can be deployed into the heart to replace
functions of stenotic valves using an endovascular approach. The
artiicial valve membranes are sewed to a stainless steel stent, and as
for angioplasty treatments the stent is brought to its inal expansion
state with a balloon catheter. The artiicial valve is brought into place
using a steerable and delectable catheter [17].

1.1.2 Laparoscopic Surgery and Single-Port Surgery

Laparoscopic surgery appeared as replacement for open-chest
or -abdomen surgeries. For this surgery, the procedure is done
usually through 3 to 5 incisions of a maximum of 12 mm diameter
on the chest or abdomen of the patient. Through 2 to 4 of them, a
variety of surgical tools are inserted to manipulate tissue and luids
inside patient. Vision of the surgical procedure is achieved using a
laparoscope inserted through the remaining port in patient's chest
or abdomen. The laparoscope is used to illuminate and capture intra-
surgical images (Fig. 1.5).
With the development of medical robotics, the multiport
coniguration is changing to single-port surgery (SPS). In this
intervention, a specialized port enables to insert multiple tools
through the same oriice. The space restrictions presented by
the single-port coniguration required the development of new
manipulation tools for this purpose.