MICROVASCULAR TECHNIQUES
19
Microvascular
techniques
Tor Chiu
Deep Inferior Epigastric Artery Perforator Flap 167
Microvascular
Techniques
I. BACKGROUND
Microsurgery has become an essential
technique in many surgical specialties.
Microsurgery is a complex task that
requires hand-microscope-eye coordination, respectful handling of delicate
tissues with microvascular instruments and
steady surgical technique.
Microsurgical skills can be improved with
regular practice. Mastering the technique
is not possible when the surgeon is limited
to observation and performing infrequent
clinical cases.
Various models can be used to train and
assess technical skills and dexterity. The
medical profession is under increasing
pressure to be able to objectively assess skills
and competence.
II. MICROSURGICAL
TECHNIQUE
A. BASIC AIMS
Water-tight anastomosis with the least
number of sutures (arteries 1 mm in
diameter ~5 to 8 and veins ~7 to 10)
Place sutures perpendicular to anastomosis
and equally spaced.
Maximize patency by avoiding constriction or suturing walls together.
B. MICROSCOPE ADJUSTMENT
There is an ON-OFF switch on the main
arm next to the brightest control. When
you switch off the microscope during
breaks, turn the brightness way down
first as – this helps to reduce the risk of
damaging the light.
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There is a dial on top of the binocular eye
pieces to adjust the interpupillary distance.
Adjust this as needed to get a binocular
image.
Gross focus is obtained by slowly moving
the lens assembly up or down. There is a
fine focus dial on the side of the base of
the lens assembly.
The magnification is adjusted by the small
dials either side of the lens assembly. The
effective magnification is calculated by
multiplying the figure on the dial with the
objective magnification, usually 10x. Thus
0.4 is equivalent to 4x. Use the middle
range of magnification rather than the
highest as it is easier and has better depth
of field.
for about 2 mm to prevent accidentally
incorporating it into the suture line.
”Circumcise“ or pull the adventitia down
over the vessel end, cut it and let it retract
and then carefully trim in a circumferential
fashion.
The vessel ends can be dilated to 1.5 times
normal diameter. Do so judiciously in living
tissue as there is a risk that this may injure
the intima.
Freeing more of the vessel from the
surrounding tissue may help to reduce
retraction when you cut the vessel.
Sutures
8-0 to 10-0 Ethilon is used depending on
the size and thickness of the vessels.
Vessel Exposure & Preparation
Take full thickness bites, approximately
twice the thickness of the vessel and tie
until the sutures are just visible.
Adventitia is cleared from the vessel ends
Forcep tips can be gently placed in the
C. END-TO-END ANASTOMOSIS
170 Dissection Manual
Figure 1
Three suture technique. The first two stay sutures are placed at 120 degrees to encourage the posterior wall to
fall away from the anterior wall when traction is exerted laterally
Figure 2
Use of traction and stay sutures to keep the back and front walls apart
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Microvascular
Techniques
lumen to protect the back wall and to
provide counter pressure. Alternatively
gently grasp the adventitia.
stitch 120 degrees from the initial two
Interrupted sutures reduce constriction
compared to continuous sutures.
complete the anastomosis
Three suture technique
stay sutures and simple square knots for
traction stitches.
Place stitches in the remaining spaces to
Surgeon’s knots are used for traction or
Place the first two stay sutures approximately 120 degrees apart on vessel‘s
circumference. The back wall will fall away
making it less likely to capture both walls.
the other stitches.
Figure 1
which allows an improved view of the
Leave the suture ends long for use as
traction sutures. There are various ways of
holding these sutures apart from a framed
clamp, choose the method that suits you
best. Complete the anterior wall. Use a
central stay suture to help you manipulate
the vessel ends. Figure 2
Rotate the anastomosis to expose the
posterior vessel wall and place a traction
172 Dissection Manual
Back wall first
Clamps are not needed with this technique
back wall. The vessel does not need to
be flipped over and it works well even in
cavities. Figure 3
The first suture is placed in the back wall at
the most difficult point to place a suture (for
right handed surgeons), right-to-left, out to
in and then in to out. An assistant can hold
the vessel ends together while the knot is
tied.
Figure 3
Back wall first technique showing the first few sutures.
Figure 4
End to side anastomosis, front wall first technique
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Microvascular
Techniques
The remainder of the back wall sutures
are placed left-to-right. The second suture
should be close to the first and subsequent
sutures can be spaced further apart. Make
liberal use of saline to visualize the vessel
intima. "Too few sutures" is easier to fix
than "too many sutures". Front wall sutures
are placed right-to-left.
D. END-TO-SIDE ANASTOMOSIS
The vessel is pinched up and a piece of
wall is carefully removed. Aim for a hole
that is about 1.5x the diameter of the
vessel to be plumbed in. The flap vessel
can be trimmed at an angle to improve
flow though a perpendicular arrangement.
The first suture is placed in the right
corner of the hole from right-to-left, out to
in and in to out.
174 Dissection Manual
The placement of the second suture
depends partly on the mobility of the
vessels. A back wall first technique is useful
when there is limited mobility.
Back wall first – subsequent sutures are
placed along the back wall.
Front wall first – the second suture is
placed at the left corner. Figure 4
KEY POINTS
1. Anastomoses should be water-tight with the least number of
sutures.
2. Place sutures perpendicularly and with equal spacing.
3. Maximize patency by avoiding constriction or suturing vessel
walls together.
4. Adventitia is cleared from vessel ends for approximately 2 mm
to prevent incorporating it into the suture line.
5. Vessel ends can be dilated to 1.5 times normal diameter.
6. Take full thickness bites, approximately twice the thickness of
the vessel and tie until the sutures are just visible.
7. Interrupted sutures reduce constriction compared to continuous
sutures.
Microvascular Techniques 175
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