Visual Servoing for Beating Heart Surgery - Visual Servoing via Advanced Numerical Methods - page 88

Fig. 6.1 Conventional off-pump CABG procedure
reducing complications, patient pain, hospital stay and recovery time would yield
a major societal impact.
In a conventional CABG, access to the heart is obtained by a large cut in the
chest along the sternum (sternotomy). The two parts of the rib cage are maintained
thanks to a retractor (see Figure 6.1). When operating on a beating heart (off-pump),
a mechanical stabilizer helps reducing the motion of the myocardium locally. The
graft, previously harvested, is used to shunt the stenosed (abnormally narrowed)
coronary artery. Connecting one side of the graft to the coronary artery requires
many sutures: this connection is called the anastomosis.
One of the main way of improvement for CABG is minimally invasiveness. Us-
ing a minimally invasive access to the heart through tiny holes in the chest pre-
vents from the complications due to sternotomy, reduces patient pain, hospital stay
and recovery time. CABG performed this way is usually called totally endoscopic
coronary artery bypass (TECAB). The other important improvement is beating heart
surgery. Letting the heart beat during CABG or TECAB prevents from some serious
complications, mainly neurological ones [8, 43]. This is now routinely performed in
open-surgery but is still challenging in a minimally invasive context. The robot is a
promising tool to help this kind of surgery. Thanks to telemanipulated endoscopic
tools with internal mobilities and stereo visual feedback, the surgeon can achieve
the grafting even on a moving organ. However, to reduce the motion of the area of
interest (AOI) (approximately 1 cm 2 around the grafting area), surgeons have to use
a heart stabilizer. It constrains mechanically and passively the relative motion be-
tween the AOI and the operation table. Despite this stabilization, the residual motion
of the AOI is still significant [27] and surgeons cannot use the same techniques for
TECAB than for open CABG, especially when suturing [18]. These workarounds
to cope with residual motion have drawbacks and limitations [21].