Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3585_Библиотеки_им_академика_М_И_Перельмана
.pdf
bc
1.8 Antegrade Approach Revisited
https://t.me/medicina_free
139
4. Plaques in the entire target vessel: The presence/properties
of plaques in the entire target vessel, as well as at the occlusion, inuence selection of the subsequent PCI strategy.
When treating a CTO that has been crossed through
the true lumen, the important considerations are the same
as those when treating a non-occluded lesion and should
include (1) the need for rotablation, (2) the need for a
Lacrosse NSE balloon, (3) the preference for a highpressure balloon, (4) the need to protect the distal coronary artery, (5) the need to protect any side branch, (6) the
need for bifurcation stenting, (7) the need for ostial stenting, and (8) the optimal size of each device.
5. Side branch at the CTO: If there is a large side branch at
the occluded segment, you should attempt to isolate the
branch by using a Crusade catheter or under IVUS guidance, provided that the IVUS catheter has been introduced into the true lumen, the ostium of the side branch is
not severely calcied, and the side branch is visible on
IVUS (Fig.1.208). If the side branch cannot be isolated
and if there is a collateral channel leading to the branch,
you should also perform retrograde PCI for the occluded
side branch. You should introduce a retrograde guidewire
into the antegrade guiding catheter to eventually accomplish stenting of the bifurcation lesion.
6. Bifurcation distal to the CTO: If the vessel undergoes
bifurcation at the distal end of the occlusion, even an
antegrade guidewire in the true lumen of the main vessel (or side branch) may not easily enter the distal
lumen of the side branch (or main vessel) (Fig.1.209).
If a guidewire that was tracking in the subintimal space
or in plaque distal to the branching point has gone into
the true lumen, the intima of the main vessel (or side
branch) may close the ostium of the side branch (or
main vessel), precluding isolation of the side branch by
antegrade wiring.
Under such circumstances, you should take the following
measures:
• Dilate the occluded vessel with a scoring balloon (e.g., a
Lacrosse NSE balloon) to make longitudinal cracks in the
intima of the main vessel (or side branch). Such cracks
may possibly extend to the intima of the side branch (or
main vessel), facilitating side branch isolation through a
Crusade catheter.
• Manipulate a CTO stiff guidewire through a Crusade
catheter to penetrate the plaque and enter the side branch
(or main vessel) (Fig.1.210).
• Approach the side branch retrogradely via any collateral
channel that is available (Fig.1.211).
• Use the reverse wire technique (Fig.1.212).
a
de
Fig. 1.208 CTO of the proximal LAD.It was difcult to identify the ostium of the side branch on CAG (a, b).An IVUS catheter was advanced
to the side branch to identify its ostium (c), leading to successful wiring of the branch (d, e)
140
https://t.me/medicina_free
1 Mitsudo’s PCI Techniques forCTO
a
b
cd
Fig. 1.209 Short CTO of the LAD (a). A guidewire has crossed the
CTO through a subintimal space and enlarged it, so a stent implanted in
the lumen may occlude the side branch indicated by arrows (b). Dilation
of the main trunk by a Lacrosse NSE balloon (c) resulted in successful
entry into the side branch (d)
1.8 Antegrade Approach Revisited
https://t.me/medicina_free
ab c
141
Fig. 1.210 CTO of the LCX (a). After a Gaia First guidewire had suc-
cessfully crossed the CTO, the ostium of the side branch indicated by a
white dotted line was closed by plaque, and it was difcult to pass a
guidewire (b). A Gaia Second guidewire penetrated the plaque obstructing the entry to the side branch (c)
abc
Fig. 1.211 CTO of the LCX (a). After failure to advance an antegrade guidewire into a side branch, retrograde tracking of a collateral channel
from the LAD led to successful wiring of the side branch (b & c)
142
https://t.me/medicina_free
1 Mitsudo’s PCI Techniques forCTO
abc
Fig. 1.212 CTO of the LCX (a). After a guidewire crossed the CTO (b), the reverse wire technique was used for isolation and wiring of the side
branch (c)
1.8.3 Retry forTracking theTrue Lumen
While keeping an IVUS catheter on a guidewire without
a stiff tip, you should use a CTO stiff guidewire with a
tip load equal or higher than that of the Gaia Second.
Before IVUS- guided wiring, you should position the
IVUS catheter so that the transducer is between the true
and false lumens. When a guidewire is advanced into the
false lumen previously enlarged by a balloon, it always
goes along the larger curvature at a bend in the vessel.
Since the true lumen must be on the smaller curvature
of the bend, you should orient the tip of the crossing
guidewire medially at the bend and use IVUS to confirm
that the tip is oriented toward the true lumen. Then you
should slightly advance the guidewire and use IVUS to
confirm that the tip is moving toward the true lumen.
After the guidewire enters the true lumen, you should
also advance the IVUS catheter to monitor the course of
the wire and confirm that it is inside the true lumen. After
confirming this point, you should advance the guidewire
slightly further to explore the correct direction and also
advance the IVUS catheter to confirm the position of the
guidewire tip. This method of tracking the true lumen
is the same as the technique for antegrade IVUS-guided
wiring of the false lumen, with the important difference
that there is no risk of further enlarging the false lumen
since its internal pressure has been reduced by creation
and dilation of a channel connecting it to the distal true
lumen. Tracking the true lumen across the entire route
from entrance to exit of the occlusion can also be monitored by IVUS.
However, the initial subintimal tracking process often
takes considerable time, which then limits the radiation exposure and time available for further interventions. In patients
with RCA occlusion, an attempt to achieve true lumen tracking is usually only made for CTOs in Segments #1–3 if a
long false lumen has previously been tracked within a relatively short time.
After a guidewire enters the true lumen of a side branch at
an occlusion, you may be unable to advance another guidewire into the true lumen of the main vessel by the parallel
wire technique. If the main vessel cannot be approached
retrogradely in this situation, tracking the true lumen under
IVUS guidance is the only remaining way to cross the CTO
to the distal true lumen (see Fig.1.128).
1.8.4 From Pre-dilatation toStenting
andPost-dilatation
When performing the steps from pre-dilatation onward,
several factors inuence the PCI strategy and determine the
optimum devices to use, as well as the optimum balloon
type, size, and ination pressure.
1.8 Antegrade Approach Revisited
https://t.me/medicina_free
143
Such factors may include the following: (1) whether the
CTO was crossed through the true or false lumen, (2) the
length of subintimal tracking if the lesion was partly crossed
via each lumen, (3) whether the occlusion is tapered or not,
(4) calcication of the lesion, (5) the presence of plaque with
attenuation, (6) negative remodeling of the occluded vessel,
and (7) whether the occlusion involves a bifurcation.
1. If the CTO was crossed through the true lumen, the fac-
tors from ③ onward should be considered. If the CTO
was crossed through a false lumen, the only option is a
simple PCI strategy consisting of balloon angioplasty
and stenting, although additional care is needed for an
occlusion involving a bifurcation.
2. If the CTO was crossed through both lumens with subin-
timal tracking for a very short distance, you can apply
the same strategy as that employed after tracking the
true lumen through the entire occlusion. However, you
should limit the size of a Rotablator burr to 1.5mm, and
the ination pressure of a Lacrosse NSE balloon in the
false lumen should be limited to 4–6atm.
3. A tapered CTO can be treated in the same manner as a
non-occluded lesion. Briey, the entire lesion should be
pre-dilated with a balloon of compatible size to the
diameter of the distal true lumen where a stent will be
implanted. Then the proximal part of the occlusion
should be additionally pre-dilated with a high-pressure
balloon or scoring balloon of compatible size to the
proximal vessel.
4. If the lesion shows calcication severe enough to pre-
vent the entry of a balloon catheter or has extensive
circumferential calcication, rotablation is often chosen.
A lesion that is less severely calcied should be dilated
with a scoring balloon (e.g., a Lacrosse NSE balloon),
while a lesion that is mainly affected by brosis should
be pre-dilated with a high-pressure balloon.
5. If there are extensive plaques showing attenuation, a l-
ter device should be placed to protect the vessel distal to
the occlusion.
It is often difcult for the Filtrap (lter) to pass
through an occlusion if it has only been dilated by a
small balloon. If so, an aspiration catheter should be
used to assist delivery to the distal segment.
If it is hard to advance the aspiration catheter through
the occlusion, a microcatheter with a large lumen should
be used together with a Parachute (lter) guidewire.
6. In patients with CTO, the occluded segment or the artery
distal to the occlusion often shows negative remodeling.
If the distal segment has undergone marked shrinkage, it
should be dilated by inating a balloon 0.5mm larger
than the vessel diameter at a low pressure such as 2atm.
If negative remodeling is only partial, the vessel
should be dilated by slowly inating a balloon of compatible size to the diameter of the vessel proximal and
distal to the remodeled region. I increase the balloon
ination pressure at the rate of 1atm per second once the
pressure has reached 4atm because rapid ination of a
balloon to dilate the vessel is generally more likely to
cause dissection.
7. If there is a branch vessel just proximal to the CTO:
Myocardial infarction resulting from occlusion of a side
branch proximal to the CTO should be prevented whenever possible. If occlusion of a side branch might result
in infarction, the branch should be protected from occlusion with a guidewire even if it is small. If balloon
angioplasty or stenting of the CTO will cause stenosis of
the side branch, the kissing balloon ination (KBI)
should be adopted.
A relatively large side branch should be treated by
stenting plus the KBI to dilate the main vessel proximal
to the branch. If the proximal segment has a large diameter so that the struts of the implanted stent cannot
approximate the vessel wall, the proximal optimization
technique (POT) should be performed followed by the
KBI (refer to Chap. 2. “Stenting of Bifurcation
Lesions”).
8. If there is a branch vessel just distal to the CTO:
Typically, this scenario is encountered when the distal
RCA bifurcates to form the posterior descending branch
and the atrioventricular branch, when a diagonal branch
originates from the LAD, and when the posterolateral
branch (Segment #14) arises from the distal LCX
(Segment #13). If a guidewire crossed through the true
lumen of the CTO at the branching point, stenting should
be done by the KBI, or culotte stenting should be
performed.
If a guidewire crossed through the subintimal space
at the branching point and if provisional T-stenting of
the main trunk may prevent guidewire entry into the side
branch, modied T-stenting may be performed.
9. If a guidewire involving a bifurcation crossed through
the subintimal space, provisional T-stenting is also difcult, so modied T-stenting should be performed.
10. A CTO of the LAD ostium is usually treated by
implanting stents through the entire LMT and the
proximal LAD using the POT and KBI.If the LMT
branches into three vessels, the POT should be used
with triple KBI.
144
https://t.me/medicina_free
Column 11 Distal Protection
If attenuated plaques are extensively distributed within the CTO, the distal coronary artery should be protected against
occlusion by plaque debris from the CTO.Among several protection methods, I choose the Filtrap lter. It is very
difcult to advance a Filtrap lter past a long CTO along a bare wire. To facilitate delivery of the lter, you should
pre-dilate the occlusion with a small balloon around 1.5mm in diameter and advance an aspiration catheter beyond
the occlusion.
Even if there is temporary “no ow” after balloon ination before delivering a Filtrap lter, I think that blood ow
through the affected vessel often recovers slowly during the next procedure. Lipids trapped by the 100-μm pores of
the lter may become fragmented, and small lipid fragments may pass through the lter into the distal vessel. Even so,
ST elevation is unlikely to occur after placement of a Filtrap lter because the capillary walls are permeable to many
small lipid fragments.
A Parachute lter guidewire can be passed through a microcatheter with a larger diameter. However, this guidewire
has a net with relatively large mesh, so it is suitable for trapping large thrombi but not for trapping small lipid particles.
1 Mitsudo’s PCI Techniques forCTO
1.9 Troubleshooting
1.9.1 Guidewire Entrapment
If a guidewire has a tip load equal to or greater than that of
a Gaia Second guidewire, its tip often becomes trapped and
difcult to withdraw from the CTO, especially after reaching
an obstruction. The tip of the guidewire may sometimes be
trapped inside severe calcication, but it is usually trapped
after the wire enters the tunica media and is advanced
through this layer for some distance.
Sometimes the guidewire enters the tunica media and
advances through it, going forward relatively smoothly along
the adventitia. In this case, the guidewire can be withdrawn
slightly, but may then become trapped so that it cannot be
withdrawn further. CTO guidewires have a small curve at the
tip, and this may prevent withdrawal of the wire.
A tightly trapped guidewire is difcult to withdraw, so
you should always check whether the tip is free or not by
pulling the wire back slightly if it stops advancing. If it is not
trapped, you can advance the wire again while exploring to
nd the right direction. If advancement of the guidewire is
blocked in a certain direction, you should never attempt to
force it forward in that direction, but should check whether
the guidewire can be withdrawn. If you cannot nd a route
through the CTO without the guidewire becoming trapped,
you should suspect that it has been blocked by a hard obstruction within the true lumen and has deviated into the subintimal space. Therefore, you should exchange the guidewire for
another with a higher tip load.
In this way, you can generally avoid tight entrapment of
a guidewire. Despite these precautions, it may sometimes be
difcult to withdraw the guidewire. If this happens, never
attempt to forcibly pull the guidewire back or rotate it excessively in the same direction, because this may lead to fracture
of the core of the wire.
If entrapment occurs, the best option is to perform 6 to
8 to-and-fro rotations of the guidewire while pulling back
slightly. You may also need to wait patiently for spontaneous release of a trapped guidewire after administration of a
coronary vasodilator such as a nitrate.
If the guidewire becomes trapped, you should advance the
microcatheter while pulling the wire back slightly. Then the
microcatheter will often enter the occlusion and reach the
site where the wire is trapped. Advancing the microcatheter
to the trapping point in this way provides optimal support
for the guidewire, allowing secure to-and-fro rotation of the
wire.
However, the proximal brous cap of a CTO may sometimes be hard enough to prevent penetration or advancement
of the microcatheter. In this situation, you will also have
to pull the microcatheter back while performing to-and-fro
rotation, but you must not pull strongly in order to avoid
fracture of the wire core. The tip of the guidewire is prone to
deformation, so the frequency and angle of rotation should
be reduced to prevent unnecessary deformation. Even if the
guidewire cannot be withdrawn despite these efforts, never
pull it back forcibly or rotate it excessively in the same
direction.
1.9.1.1 If aTrapped Guidewire Cannot
BeWithdrawn
If a guidewire cannot be withdrawn after trying the abovementioned maneuvers for several minutes, it may be a good
ab
1.9 Troubleshooting
https://t.me/medicina_free
145
idea to wait for reversal of vasospasm of smooth muscle
caused by the wire. You should advance another guidewire
by the same approach or the contralateral approach, aiming
to achieve direct crossing of the CTO while simultaneously
making preparations for bailout. If the guidewire remains
trapped for a long time, you should attempt the following
bailout procedure:
If an antegrade guidewire has been trapped, one of the
most likely solutions is to advance another guidewire by the
parallel wire technique and enlarge the space where the rst
wire is trapped by inating a balloon (Fig.1.213).
Crossing the occlusion with a retrograde guidewire and
then enlarging an adjacent space with an antegrade balloon
is an acceptable variation of the above method (Fig.1.214).
In some cases, you may attempt the reverse CART technique and use the antegrade guidewire for ballooning
(Fig.1.215).
Entrapment of a retrograde guidewire is a more serious
problem because it is very difcult to recover a guidewire if
its core is ruptured and the spring coil is stretched. A guidewire is often trapped after its advancement has been blocked
by an obstruction. If advancement of a retrograde guidewire
is blocked, you should attempt to pull it back slightly as
soon as possible. If the guidewire cannot be withdrawn at
all, you should continue to pull back slightly while performing to- and- fro rotation until it moves. If you still cannot free
the wire even after administration of a nitrate, you should
advance another guidewire antegradely toward the distal true
lumen by the kissing wire or parallel wire technique until it
is distal to the entrapment point. Even if the antegrade guidewire cannot reach the distal true lumen, if you can enlarge
a space near the entrapment point by advancing a balloon
over the antegrade wire, you should be able to withdraw the
trapped retrograde guidewire and accomplish reverse CART.
Fig. 1.213 Guidewire entrapment. In a patient with CTO of the proxi-
mal RCA (a), direct antegrade crossing of the occlusion was attempted
with a Gaia Second guidewire using the anchor balloon technique
because the guiding catheter provided poor backup. However, the
guidewire tip became trapped and its core fractured, leaving the spring
coil in the occlusion (b). To recover this part of the fractured wire, a
Conquest Pro guidewire was advanced along the rst guidewire, and
then a balloon catheter was also advanced to that point. After a space
was created by inating the balloon, the spring coil was successfully
recovered using a snare
146
ab
https://t.me/medicina_free
Fig. 1.214 Solution for guidewire entrapment. (a) Cross the occlusion
with a retrograde guidewire. (b) After you achieve access for a balloon,
advance a balloon to near the point of entrapment, and inate it to
enlarge the space. This may help to free the tip of the guidewire and
permit its withdrawal
1 Mitsudo’s PCI Techniques forCTO
1.9.1.2 If theGuidewire Core Is Fractured
andtheSpring Coil Is Stretched
With regard to the products made by Asahi Intecc, guidewires in the Miracle series are unlikely to become trapped
because the diameter of the tip is the same as that of the shaft
(0.014″), providing a large torque, and because the tightly
wound spring coil allows these wires to tolerate rotation even
in the muscular layer or in calcied plaque.
Gaia and Conquest Pro guidewires are more likely to
become trapped because they have a tapered tip (0.009″ to
0.011″) and thus a smaller torque. In particular, fracture of
the core of the wire is likely to occur if Gaia guidewires are
rotated repeatedly because the tip shaft is not stiff and the
spring coil is not wound tightly. While wires in the Conquest
Pro series are also susceptible to trapping, fracture of the
core is less likely because these guidewires have a stiff core
and tightly wound spring coil.
If the core of a guidewire is fractured, the guidewire
can be pulled back with almost no resistance by applying a
slight force that is sufcient to stretch the spring coil. Never
completely withdraw a guidewire, even if it can be pulled
back easily. If the proximal part of the stretched spring coil
snaps and remains inside the guiding catheter, it is difcult to
recover this part of the guidewire with a snare.
Fig. 1.215 Solution for guidewire entrapment. Perform the reverse
CART technique, and inate a balloon at the point of entrapment. This
may help to free the tip of the guidewire and permit its withdrawal
1.9.1.3 Recovering aSpring Coil Connected
totheProximal Guidewire Shaft
If possible, you should enlarge the space around the trapped
tip of the guidewire by inating a balloon introduced along
another guidewire (Fig.1.216a & b). If you cannot advance
another guidewire or inate a balloon, you should advance a
snare along the spring coil as far as possible before attempting to capture the spring coil with the snare and withdraw it
(Fig.1.216c). If a GuideLiner catheter is advanced along the
stretched spring coil to near the proximal end of the occlusion, it will provide good support to the distal portion of the
spring coil and facilitate its recovery.
ab
1.9 Troubleshooting
https://t.me/medicina_free
c
Fig. 1.216 Recovering a guidewire after rupture of the core (a). (b)
Advance a balloon along another guidewire and inate it. (c) Advance
a snare as far as possible to capture the ruptured guidewire and withdraw it
147
Fig. 1.217 Recovering a guidewire after rupture of the core and
fracture of the shaft. It is difcult to capture the damaged guidewire
with a snare inside the guiding catheter. Therefore, you should
inate a balloon to anchor the spring coil within the guiding catheter
and then withdraw the guidewire together with the whole PCI
system
1.9.1.4 If theProximal Part oftheSpring Coil Has
Become Separated fromtheGuidewire
Shaft
In this situation, a guidewire cannot be used to advance a
snare. The separated spring coil (due to its neness, softness,
and winding shape) contacts the wall of the guiding catheter over a large area, so attempts to capture the spring coil
with a snare inside the guiding catheter often fail as the snare
just pushes the coil aside and cannot be advanced beyond its
proximal end. However, you can advance a guidewire or a
small balloon through the guiding catheter beyond the spring
coil. Therefore, you should be able to inate a balloon about
2.5mm in diameter near the tip of the guiding catheter at a
pressure of not less than 10atm and then withdraw the guidewire together with the guiding catheter (Fig.1.217).
1.9.1.5 If aStretched Spring Coil Has Escaped
fromtheGuiding Catheter
While conrming the position of the proximal end of
the spring coil by uoroscopy, you should advance a
large (15mm) snare from the guiding catheter and catch
the proximal end of the coil with the loop of the snare
(Fig.1.218). After capturing the coil with the snare, you
should advance the guiding catheter to the ostium of the
coronary artery. As mentioned above, you should then
inate a balloon inside the guiding catheter near the coronary ostium and withdraw the spring coil together with the
guiding catheter.
148
https://t.me/medicina_free
Fig. 1.218 Recovering a spring coil that has escaped from the guiding
catheter. While conrming the position of the proximal end of the
spring coil, capture it with a large snare and pull it into the guiding
catheter. Inate a balloon within the guiding catheter to anchor the coil
and then withdraw it together with the PCI system
1.9.2 Perforation by theGuidewire
Coronary artery perforation by the guidewire tip most commonly occurs with CTO crossing guidewires. To prevent
this complication, you should take the following precautions
when performing PCI for CTO:
1. Once an antegrade guidewire has crossed the CTO, do not
advance it much further.
2. Do not vibrate a balloon while advancing it.
3. Once a microcatheter has crossed the CTO, immediately
exchange the guidewire for a non-tapered spring coil
guidewire with a lower tip load and moderate
slipperiness.
4. After inating a crossing balloon, promptly exchange the
balloon catheter for a microcatheter, and also exchange
the guidewire for another wire (using a Kusabi catheter
rather than an extension wire for the safety).
Use a non-tapered spring coil guidewire in the main vessel.
While advancing the guidewire beyond a branching point in
the proximal segment, you should carefully monitor the position of its tip as the guidewire may go too far or deviate into a
side branch and cause perforation of the smaller vessel. If the
guidewire causes perforation despite these precautions, you
should take the following measures to achieve hemostasis:
1 Mitsudo’s PCI Techniques forCTO
1. Administer protamine intravenously to neutralize about
half of the antithrombin effect of heparin (if 10,000units
of heparin was administered, the initial dose of protamine
should be 50mg [10,000 ÷ 200]). If the activated clotting
time (ACT) becomes about 120 to 150seconds, further
doses of protamine are not required.
2. If hemorrhage originates from a small side branch,
place a balloon of a size compatible with the diameter
of the distal coronary artery segment in the main vessel
across the branching point, and inate it at 2–4 atm
(Figs.1.219a & 1.220). Conrm the absence of antegrade hemorrhage, and keep the balloon inated for
5–10minutes.
3. If the main vessel has been perforated directly, place a
balloon in the lumen at the site of hemorrhage, and inate
it at a low pressure for a long period as explained above
(Figs.1.219b, 1.220, & 1.221).
4. During balloon ination, ush the guiding catheter and
the dilated coronary artery with heparinized saline every
1–2minutes to prevent thrombus formation.
5. Hemostasis can usually be achieved by measures (2) or
(3). If hemostasis cannot be obtained with these measures, repeat prolonged balloon ination. If hemostasis is
still not achieved, but blood loss is decreasing, repeat prolonged balloon ination again. To prevent thrombus formation, continue to perform measure (4) without fail until
hemostasis is achieved.
6. In rare cases, even prolonged balloon ination will fail
to obtain hemostasis, and delivery of a hemostatic plug
through a microcatheter will be required. The following
can serve as a hemostatic plug: (1) a blood clot formed
by arterial puncture, (2) subcutaneous fat, (3) hemostatic material such as Spongel, and (4) a coil. To deliver
a blood clot or a block of subcutaneous fat into the
bleeding vessel, inject it by using saline mixed with an
equal volume of contrast medium. Both a blood clot
and subcutaneous fat will oat in an equal mixture of
saline and contrast medium. Inject the hemostatic plug
oating in saline/contrast medium into a microcatheter
through a syringe with the hub kept upward, and stop
injection when the bleeding vessel can be imaged for a
distance of several millimeters. Withdraw the microcatheter until its tip reaches the site where sufcient
backow of blood is detected, and slowly perform tip
injection to conrm hemostasis. If tip injection is too
rapid, it may push the hemostatic plug away and lead to
recurrent bleeding, whereas uncontrolled hemorrhage
may be missed if the microcatheter reduces the distal
perfusion pressure and tip injection is too slow. Final
CAG should be performed via the guiding catheter after
placing the tip of the guidewire in the side branch or in
the proximal segment and after pulling the microcatheter back sufciently.
Соседние файлы в папке Библиотека им академика М.И. Перельмана