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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3823_Библиотеки_им_академика_М_И_Перельмана
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Step 7. To redirect to a different branch or to the other
lung, the diagnostic catheter is reintroduced over the
wire and the above steps are repeated. If aspiration is
unsuccessful at removing thrombi, especially when the
latter are impacted in the distal vessels, the self‐
deploying disks can be advanced over the wire inside the
F20 and unsheathed in the distal vessel (Figure 16.10).
Once deployed, they are withdrawn into the F20 while
syringe aspiration is activated.
Tip: Merely withdrawing the disks without negative
suctioning is unlikely to be effective in thrombus
removal.
Figure 16.9 Thrombi extracted via aspiration through
the F20.
Figure 16.10 Positioning (a) and deployment (b) of
FlowTriever catheter and disks.
Notes: The endpoint of the aspiration process is poorly
defined. The authors typically terminate the procedure
when one or more of the following occurs: (i) patient
significantly feels better with improvement in saturation
and/or heart rate; (ii) significant thrombus has been
removed with evidence of better perfusion on
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angiography; (iii) significant improvement in PA
pressure and/or cardiac output has been achieved; and
(iv) no thrombi are being removed despite multiple
passes, typically seen in the more chronic emboli.
Step 8. Hemostasis can be achieved either with a
mattress or figure‐of‐8 suture, or with a closure device
(Proglide) deployed prior to insertion of the large sheath.
Note: Large catheter aspiration is attractive for
patients with high‐risk PE with contraindication to
thrombolysis and for patients with intermediate‐risk
PE at risk for deterioration, especially when
thrombolytic use is to be avoided. Patients stabilized
with this procedure may avoid ICU stay. Potential
complications include those of vascular access,
tricuspid valve or cardiac injury, PA
perforation/hemorrhage, or
hemodynamic/pulmonary deterioration related to
distal embolization of saddle or intracardiac
thrombi.
Penumbra
The Penumbra’s Indigo® system (Penumbra Inc.,
Alameda, CA, USA) does not have a specific approval for
use in the pulmonary arteries, but it is FDA approved for
removal of thrombus in the peripheral venous and
arterial system. The thrombectomy catheters suction by
continuous vacuum generated aspiration through its
Penumbra Engine™ (Penumbra Inc., Alameda, CA, USA)
aspiration source.
For the purpose of thrombectomy for proximal
pulmonary emboli, the largest catheter CAT8
(Continuous Aspiration Mechanical Thrombectomy
Catheter 8) should be used. The CAT8 is available in
three shapes: Straight (85 cm), Torq (85 cm), and XTorq
(115 cm). The author prefers the XTorq shape (115 cm),
given length and ability for circumferential aspiration. A
#8 separator is needed to clear the lumen of the
aspiration catheter during active suction.
Step 1. Obtain ultrasound‐guided venous access
(femoral or jugular) using standard technique. A 65 or
90 cm 8 Fr sheath guide (Terumo Pinnacle
®
Destination®, TERUMO Medical Corporation, Somerset,
NJ, USA), or long sheath should be advanced over a wire
(0.035 angled or J‐tip wire) into the RA or proximal
portion of the targeted pulmonary artery.
Tips: (i) A 90 cm length sheath cannot be used if the
CAT8 straight (85 cm) or CAT8 Torq (85 cm) is used
due to length mismatch. (ii) If using a Cook Flexor
®
sheath (Cook Medical LLC, Bloomington, IN, USA),
with a Check‐Flo valve a 10 Fr is required to
accommodate the CAT8. (iii) A 6 Fr JR4 catheter
can be telescoped through the sheath guide or long
sheath to help steer the guidewire into the
pulmonary artery.
Step 2. Once access is obtained, the patient is
heparinized (80–100 U/kg bolus) to an ACT ≥250.
Step 3. The packaging of the aspiration catheter and its
lumen and separator are flushed with heparinized saline.
The catheter is inserted through a rotating hemostasis
valve on the guide sheath or through the valve of the
sheath using the peelable introducer sheath on the
aspiration catheter. Once inserted the peelable sheath is
removed from the aspiration catheter.
Tip: The peelable sheath can be kept on the catheter
in the event the catheter needs to be removed from
the sheath and then reinserted.
Step 4. The aspiration catheter is advanced over the
wire into the targeted segment in the pulmonary artery
and positioned immediately proximal to the thrombus.
The guidewire is then removed. Contrast can be injected
through the aspiration catheter to obtain a selective
pulmonary angiogram to visualize thrombus locations. If
not contraindicated, a small bolus of tpa (2–5 mg) can
also be injected through the aspiration catheter.
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Step 5. Aspiration tubing is then attached to the
aspiration pump and turned on. The valve on the
aspiration tubing should be in the OFF position. Gauge
should read −20 mmHg or greater.
Step 6. The aspiration catheter is advanced and
embedded in the thrombus. A #8 separator is then
inserted through the rotating hemostasis valve into the
aspiration catheter. The aspiration tubing is connected to
the side port of the rotating hemostasis valve. The valve
on the aspiration tubing is switched to ON to begin
aspiration, and the separator is advanced and retracted
during active suction. The aspiration catheter can be
rotated to engage additional thrombus.
Safety Tips: (i) Never retract, advance, or torque the
catheter or separator against resistance as this could
lead to vessel damage and perforation. (ii) The
separator should not be used as a guidewire to
advance the catheter.
Step 7. To stop aspiration the aspiration tubing valve is
switched to the OFF position and then the pump can be
turned OFF. The separator is removed. A volume of 5–
10 ml of blood should be aspirated from the catheter and
once the catheter is cleared, it can be used to hand inject
contrast. If further treatment of smaller distal branches
(vessel size 2–3 mm) is needed, the CAT3 device can be
used by telescoping through the existing sheath or CAT8
device.
Safety Tip: During active aspiration a nurse or
technician should pay close attention to the amount
and speed of blood removal into container. This
should be continuously verbalized to the operator.
When the aspiration catheter is engaged in
thrombus, blood is seen slowly dripping out into the
canister. If flow stops completely despite use of the
separator, the catheter should be withdrawn and
flushed to remove trapped thrombus. If blood flow is
more rapid and continuous, this is indicative that
clot is not being engaged or removed and flow
should be either interrupted or the catheter
repositioned to avoid excessive blood loss. If there is
substantial aspiration of blood as the procedure
warrants, consideration can be made to replete with
a packed red blood cell transfusion.
AngioVac
The AngioVac® system (Angiodynamic, Latham, NY,
USA) is a large‐bore suction thrombectomy device
indicated for removal of fresh, soft thrombi or emboli
during extracorporeal bypass. The system utilizes a 22
French coil reinforced aspiration cannula with an
expandable funnel tip that can engage and aspirate large
thrombi. Aspiration is achieved by attaching the cannula
to a cardiopulmonary bypass circuit, where the blood is
filtered and then is then returned to the patient via a
large‐bore return cannula via a second central venous
access (Figure 16.11).
It currently is available in straight, and 20°
configurations with a balloon‐actuated expandable
funnel (generation 2) (Figure 16.12a) as well as a
configuration (generation 3) (Figure 16.12b) which
allows up to 180° angulation of the catheter by
unsheathing the distal end of the cannula. The funnel on
third‐generation device is expanded by nitinol struts in
the leaflets and is deployed by unsheathing the funnel.
Large thrombus in the setting of pulmonary embolism
may be amenable to removal utilizing the AngioVac
system [6, 7]. The AngioVac also shows promise in the
treatment of clot‐in‐transit in the right atrium/ventricle
[8]. It can also be utilized effectively for debulking large
infected right heart vegetations to prevent septic
pulmonary embolism [9, 10].
Patient Selection and Central Venous Access
As this device requires large‐bore sheath and cannula
access into central veins, documentation of patency of
two suitable accesses should be ascertained, including
evaluation of both internal jugular veins and both
common femoral veins. There should be no absolute
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contraindication to anticoagulation. Patients with
heparin allergies can be anticoagulated with argatroban
or bivalirudin. Right heart vegetation procedures are
often facilitated in conjunction with real‐time
transesophageal echocardiography (TEE) guidance,
necessitating anesthesia services, and an operator of the
echocardiography imaging equipment. Intracardiac
echocardiography (ICE) has also been used to facilitate
right heart vegetation removal [11], which may obviate
the need for general anesthesia. Clot‐in‐transit
embolectomy procedures can be performed with
intraprocedural transthoracic echocardiography (TTE)
monitoring, as general anesthesia may not be desirable
in patients with pulmonary embolus.
Figure 16.11 AngioVac system utilizes a large
intravascular cannula attached to a cardiopulmonary
bypass circuit where blood is filtered and then returned
to patient.
Source: Image courtesy of AngioDynamics, Inc. and its affiliates.
Figure 16.12 (a) Generation 2 device with balloon‐
actuated funnel, straight and 20° fixed angulation.
Source: Courtesy of AngioDynamics, Inc.
(b) Generation 3 device with funnel expanded by nitinol
struts and flexible cannula up to 180° angulation.
Source: Courtesy of AngioDynamics, Inc.
AngioVac Circuit Setup and Thrombus
Aspiration
Step 1. Venous access should be obtained in two central
veins (internal jugular vein or common femoral veins).
Ultrasound guidance is recommended for access to avoid
inadvertent arterial injury before large‐bore sheath
placement and anticoagulation.
Tip: The preclose technique can be performed after
obtaining access, before dilating to larger French
size at the venous access sites by placing a purse‐
string suture at each access site or placing a single
Perclose ProGlide (Abbott, Santa Clara, CA, USA)
suture at this time if desired.
Step 2. Intravenous anticoagulant bolus can be
administered at this point before placement of reinfusion
cannula to prevent thrombus from forming in the
cannula (a minimum target of ACT of 300 is desired
while blood is in the circuit).
Step 3. Serial dilatation is then performed at each
venous access site, respectively, 16 or 18 Fr reinfusion
cannula is placed at one site, and a 26 Fr DrySeal sheath
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(W.L. Gore, Flagstaff, AZ, USA) is placed at the site
desired for aspiration.
Step 4. The circuit is opened in the sterile field, and the
Y‐circuit hub is connected to the female connector,
closing the circuit of the operator’s side (Figure 16.13a).
A Tuohy‐Borst adaptor is inserted into the red Tuohy on
the Y‐adapter; both are tightened to finger tight (Figure
16.13b). An adequate amount of sterile circuit tubing is
left on the field, and the remainder of the circuit is
passed off to perfusionist for circuit assembly (perfusion
circuit assembly is not included in this description).
Step 5. After the circuit is primed, clamps are placed on
the ends of the tubing, marked by a blue line and red
line, respectively, ensuring the circuit remains primed
(Figure 16.13c). The two ends are then separated again. A
wet‐to‐wet connection is made at the reinfusion cannula,
ensuring there is no air in the tubing.
Tip: A stopcock and a 60 cc syringe can be used to
aspirate any residual air from the return tubing.
The Y‐adaptor end is connected to the AngioVac cannula
(Figure 16.13d), the clamp is removed, and the cannula is
then primed with saline. The Tuohy insert is removed,
and the obturator is inserted until it is entirely through
the distal end of AngioVac cannula (Figure 16.13e). The
clamp is removed and cannula flushed. The AngioVac
cannula can then be advanced through the DrySeal
sheath over a wire to its desired location, and the
obturator is then removed.
Figure 16.13 (a–e) AngioVac circuit assembly.
Source: Courtesy of AngioDynamics, Inc.
Tip: If the AngioVac does not need significant
intravascular manipulation, the cannula can be
directly advanced through the DrySeal sheath
without the obturator, taking care not to damage the
leaflets as it enters the hub. The cannula can then be
unsheathed to avoid advancing it into the vessel
wall.
Step 6. With the second‐generation AngioVac device, an
inflator is used to distend a balloon which deploys
funnel. The balloon should not be inflated more than 2
mmHg as it may rupture. With the third‐generation
AngioVac device, the funnel is deployed by unsheathing
the end of the cannula.
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Tip: With the second‐generation device, if the
balloon ruptures, the leaflets of the cannula may not
open properly, limiting flows.
Step 7. All clamps are removed, and flow is initiated and
optimized to approximately 3–4 l/min.
Step 8. AngioVac cannula is then advanced to engage
the thrombus.
AngioVac for Pulmonary Embolus
AngioVac can engage and remove large thrombus and
may be a useful tool in the treatment of large central
pulmonary embolus, especially when the use of lytics
may be contraindicated. Note, however, the use of
AngioVac in the pulmonary arteries constitutes off label
use of the device.Because of the size and rigidity of the
current iteration of the cannula, manipulating through
the right heart into the pulmonary arteries may prove
challenging. Also, the cannula cannot be advanced past
the main pulmonary arteries and may be less effective in
the treatment of isolated peripheral segmental
thrombus. Caution must be taken when manipulating
the cannula across the tricuspid valvular apparatus
during catheter placement to avoid valvular injury. When
crossing the tricuspid valve, care must be taken to avoid
hooking chordae tendineae of the valve. This can be
achieved by using an inflated Swan–Ganz balloon
catheter or a formed pigtail catheter with a tip deflecting
wire to cross the valve into the right ventricle/pulmonary
outflow tract. This can then be exchanged for a stiff wire,
i.e. a super‐stiff Amplatz wire or a Lundquist wire, to
facilitate the delivery of the AngioVac cannula to the
pulmonary artery. The cannula is advanced with the
obturator to the pulmonary artery, central to the clot.
The obturator is removed, the funnel expanded, and flow
is then initiated before the thrombus in engaged.
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