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284 Chapter 28 Indications, techniques, and results of inferior vena cava filters
https://t.me/med1917
TABLE 28.4 Retrievable inferior vena cava lters
Name Manufacturer Year introduced Delivery
Günther
Tulip
Celect Cook 2009 7.0 Fr Cobalt
Denali Bard 2010 8.5 Fr Nitinol Compatible NA Approved
OptEase Cordis 2003 6.0 Fr Nitinol Compatible 23 days Approved
Option Elite Argon 2013 5.0 Fr Nitinol Compatible NA Approved
ALN ALN Implants
Cook 1992 (available in
the United States
since 2001)
2012 5.0 Fr Stainless steel Compatible NA Approved
Chirurgicaux
system size
8.5 Fr Elgiloy Compatible 14 days Approved
Material Magnetic
resonance
compatibility
Conditional NA Approved
chromium alloy
Recommended
time for retrieval
FDA approval
for retrievable
use
alloy) wires formed in a conventional conical conguration
with welded hooks, some oriented superiorly and others
inferiorly. The lateral side-rail conguration of these wires
allows for caval centering and stabilizing. The low-prole
lter can be deployed from femoral, jugular, or antecubital
routes, and the low-prole design uses a cartridge injection
system to properly orient the lter for femoral or jugular
uses.
28.5.5 Simon nitinol filter
The conguration of the lter uses a conical array of six
struts with hooks at the base and a daisy-wheel conguration of wires at the lter apex, in effect providing two
levels of ltration. The lter daisy wheel has seven overlapping loops. The lter is manufactured from nitinol
(nickel and titanium alloy), which has unique thermal-mechanical memory properties that allow the lter to exist
in the straightened but exible form at room temperatures
(<27°C) within the 7-Fr delivery carrier and re-form into
a predetermined designed lter shape at body temperatures. The lter is designed for IVC diameters of 28mm
and smaller. The lter can be deployed from the femoral,
jugular, or antecubital routes.
28.5.6 TrapEase filter
The TrapEase lter is a signicant departure from the conical design introduced by Greeneld. It has a double-basket
symmetric conguration with cephalad and caudad baskets in a six-diamond or trapezoidal shape, and the baskets
are then connected by six straight struts, which contain
proximal and distal hooks for xation within the IVC. The
lter can be inserted by femoral, jugular, or antecubital
approaches. The TrapEase IVC lter can be used in patients
with IVC diameters of 30 mm and smaller. Recent data
suggest that the TrapEase—and by association the retrievable version of this lter, the OptEase—may be associated
with an excessive rate of IVC thrombosis.
28.5.7 Bird’s nest filter
This lter consists of four stainless steel wires (25 cm
long by 0.18 mm) attached to two V-shaped struts. The
V-shaped struts have small barbs at the two ends to engage
the IVC wall. During insertion, the four wires are extruded
from the delivery system in a random distribution, simulating a bird’s nest. The lter is approximately 7cm long,
but in practice, the deployed length varies by the amount
of overlap of the “V” struts. It can be placed in IVCs with
diameters as large as 40mm. It can be placed by femoral
or jugular routes. The lter generates the largest magnetic
resonance imaging artifact of all the lter devices because
of the stainless steel construction.
28.5.8 Retrievable filters
With optional retrievable IVC lters, the venous system is
reaccessed at a later date for retrieval of the lter if desired.
The rst retrievable lter to become commercially available in the mid-1980s was the Amplatz device, but this
lter was removed from the market due to a high rate of
IVC occlusion. Table28.4 lists the commercially available
retrievable IVC lters available in the United States. The
time of retrieval for these lters varies with the device, and
there are multiple case reports of lter retrieval several
months to years after placement. In general, retrieval of
lters must be performed as soon after placement as clinically possible, because endothelialization of lter struts to
the IVC wall has been described to occur as soon as 12
days after lter placement.
21
28.5.9 Günther Tulip and Celect filters
This lter consists of four main struts congured as a cross
with 1-mm-long hooks at the inferior end for IVC xation. Each strut has an elongated wire loop that extends
inferiorly three-quarters of the length from the apex to
the hooked end of the four main cross struts. The lter is
30mm in diameter and 50mm long in the fully expanded
28.5 Types of IVC filters 285
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state. Whereas the lter can be placed from either femoral or jugular access sites, retrieval is performed from the
right jugular site with use of a retrieval snare and an 11-Fr
sheath. It is recommended by the manufacturer that the
lter removal is done within 14 days of implantation, but
“conventional wisdom” suggests that removal out to 8
weeks is possible. Data suggest that the Günther Tulip may
be safely removed at 30 days with minimal, if any, complications,
been reported.
22
and removal out to 126 days after placement has
23
28.5.10 Celect
The Celect is a cobalt-chromium lter that also consists
of four main hooked struts for IVC xation, as well
as eight shorter secondary legs that provide additional
outward support. The lter has a maximum diameter of
30mm and is 45 mm long when deployed. It may be
delivered via a jugular or femoral approach with a 7-Fr
sheath and retrieved using a looped snare through an
11-Fr sheath.
28.5.11 Recovery filter/Generation 2 filter/
G2X/Meridian filter/Eclipse/Denali
The Bard series of retrievable lters started with the Recovery nitinol lter, which was the rst lter to have a retrieval
indication in the United States. The Recovery nitinol lter
was subsequently replaced by the Generation 2 (G2), which
was later renamed the G2X. Both the Recovery and the G2
lters have two levels of ltration, similar to the Simon nitinol lter. These lters have six arms and six legs (upper and
lower ltering elements, respectively). The Recovery lter
was retrieved from the right jugular vein approach with a
retrieval cone that was fabricated from nine metal claws
covered with urethane material. The G2 lter was modied by increasing its resting diameter, changing the angulation of the wires forming the upper ltering elements, and
changing the metallic composition of the hooks attached
to the lower ltering elements. Both the recovery and G2
lters were reported to have high rates of strut fracture.
One study noted that strut fracture occurred in 25% of
Recovery lters and 12% of G2 lters, potentially leading
to severe complications, including ventricular tachycardia
and tamponade.
eventually removed from the market. Subsequent design
changes led to the Eclipse, Meridian, and nally the Denali
lters. Only the Denali is presently available for use in the
United States. The Denali is a nitinol lter consisting of 12
legs with two levels of ltration, much like the Eclipse. This
lter has two longer anchors and four midsized legs with
hooks and anchors that provide the rst level of ltration.
An additional six shorter legs stabilize the lter and provide a second level of ltration. The lter comes preloaded
in a storage tube with a pusher. The delivery system uses an
8.4-Fr sheath and can be deployed in an IVC with a maxi-
mum diameter of 28mm.
24
Both the Recovery and G2 lters were
28.5.12 Option and Option Elite
The Option is an over-the-wire nitinol lter that consists of
six hooked struts for caval xation. This is the lowest-prole lter currently available and utilizes a 5-Fr sheath that
has an outer diameter of 6.5 Fr. The Option also has an
optional 100-cm delivery sheath and is one of the only
IVC lters approved for popliteal access. The over-the-wire
delivery system for the Option Elite lter is designed to aid
in centering the lter on delivery.
28.5.13 ALN
The ALN is a cone-shaped lter with three long, curvilinear centering struts and six shorter anchoring struts with
curved hooks for xation. The struts are all variable in
length to prevent entanglement when loaded in the 7-Fr
delivery sheath. The delivery sheath is available in 600mm and 1200-mm lengths to support femoral and IJ
access, as well as popliteal and brachial access; however,
the popliteal conguration is not currently available in
the United States. The ALN lter is approved for use in
caval diameters of up to 32mm and is available with
or without a hook on the lter base for retrieval. The
hooked system can be retrieved with a looped snare,
while a pincer retrieval system is used for the nonhooked
lter.
28.5.14 OptEase filter
The OptEase lter has a dual cone (symmetrical) design
that is nearly identical to the TrapEase. The OptEase lter has been modied with the placement of unidirectional
barbs and an apical hook for removal and can be inserted
from the jugular or femoral routes with the same 6-Fr
introducer sheath (by reorienting the lter). This lter is
retrieved from the femoral vein only by snaring a small
hook at the caudal end of the lter. Notably, in 2013, the
Food and Drug Administration (FDA) issued a class Irecall
on OptEase lters due to confusion with the labeling of the
lter and to avoid loading the lter backward. There were
no problems with the device itself.
28.5.15 Crux
The Crux lter also varies signicantly from the traditional
conical lter design. The Crux is composed of a nitinol
frame made of two sinusoidal wave forms connected at
the ends. When deployed, the lter forms a partially sandwiched gure of 8 within the IVC. One loop contains a
webbed expanded polytetrauoroethylene (ePTFE) mesh
to trap emboli. There are ve tissue anchors along the outer
frame that secure the lter in place. There are retrieval tails
at either end of the lter, so that bidirectional retrieval can
be performed. The Crux was FDA approved in 2012; however, it does not appear to be commercially available at this
time.
28
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28.6 TEMPORARY FILTERS
Temporary lters, by denition, remain attached to the
delivery system. This facilitates retrieval, but the external
portion increases the risk of infection. Temporary lters are
not clinically available in the United States and are associated with poor outcomes in small European studies.
39,40
Two of the earliest caval interruption devices were designed
for temporary use. These include the Eichelter sieve and the
Moser balloon. These were soon abandoned in response to
concern regarding the fate of trapped embolus.
25
28.7 BIOABSORBABLE AND
CONVERTIBLE FILTERS
To address the issue of high rates of nonretrieval in retrievable IVC lters, an adsorbable IVC lter was developed
made of polydioxanone suture with anticipate adsorption to
occur within 5 weeks. This was demonstrated in swine to be
safe for prevention of PE for at least 5 weeks,
in-human study performed in 2020 showed no lter-related
adverse events.
27
The Sentry device was designed as a bioco-
26
and a rst-
vertible device which consists of a nitinol shell, with a cone
created by biodegradable poly-p-diaxanone. Two-year safety
data demonstrated two incidences of early caval thrombosis
(1.6%), but otherwise no lter-related complications.
28
Convertible lters were introduced in 2017 in response
to the challenges with retrievable lters. The VenaTech
Convertible Vena Cava Filter (B. Braun Interventional
Systems, Inc, Bethlehem, PA), is designed similar to the
VenaTech LP permanent lter, which can be converted into
an open conguration when the risk of VTE is mitigated.
In a multicenter IDE trial of 149 lter implants, 96 were
converted during the 6-month study period with a 96.9%
technical success rate for conversion.
29
Additional 6-month
follow-up demonstrated low rates of adverse events in the
converted conguration and a signicant reduction in IVC
thrombosis compared to the nonconverted group (0% with
conversion, 14.3% in nonconverted conguration).
30
An
advantage of the convertible lter is the ability to convert it
at a specied time, but this does still require an additional
procedure. Long-term data are yet to be published.
28.8 PERMANENT, RETRIEVABLE, OR
CONVERTIBLE?
The development of optional retrieval devices was largely
driven by the results of the Prévention du Risque d’Embolie Pulmonaire par Interruption Cave (PREPIC) trial.
The PREPIC trial was the rst of only two randomized
controlled trials involving IVC lters. The study was a
multi-institutional trial of 400 patients with conrmed
acute proximal DVT who were randomized to receive
either anticoagulation alone or anticoagulation and a
permanent IVC lter. The initial 2-year results from the
PREPIC found that at 12 days there were two PEs (1.1%)
in the lter group compared to nine (4.8%) in the no-lter group (P= 0.03), resulting in an odds ratio (OR) of
0.22 (95% CI: 0.05–0.90). After 2 years, there were six
PEs in the lter group compared to 12 in the no-lter group
(P=0.16). The overall incidence of recurrent DVT in the
lter group was 20.8% compared to 11.6% in the no-lter
group (P=0.02), for an OR of 1.87 (95% CI: 1.10–3.20),
although there was no signicant difference in recurrent
DVT at 1year after enrollment.
31
The 8-year follow-up of
the PREPIC trial found nine PEs (6.2%) in the lter group
compared to 24 (15.1%) in the no-lter group (P=0.008),
resulting in an OR of 0.37 (95% CI: 0.17–0.79). Recurrent
DVT occurred in 35.7% in the lter group, compared to
27.4% in the no-lter group (P=0.042). At 8years, there
was no signicant difference in mortality between the lter
and no-lter groups and no signicant difference in incidence of post-thrombotic syndrome.
32
The results from the
PREPIC study suggested that IVC lters provide a reduction in risk of the development of PE when combined with
anticoagulation, but no improvement in mortality. Furthermore, the benet in terms of reduced risk of PE comes at
the expense of an increased risk of recurrent DVT, although
this did not translate to a higher risk of post-thrombotic
syndrome.
While the PREPIC trial was heralded as the rst randomized controlled trial to explore the benets of IVC lter use
in patients with DVT, the study had several notable aws in
its design and analysis. First, study participants were randomized using a 2 × 2 factorial design, so individuals were
randomized to receive either enoxaparin or unfractionated
heparin in addition to either an IVC lter or no lter. With
enrollment of 400 patients, the study was underpowered
for such an analysis.
33
Additionally, the PREPIC trial evaluated IVC lters only in patients who were concomitantly
receiving anticoagulation; thus, the population in which
lters are most frequently deployed (patients who cannot
be anticoagulated) was not examined.
34
Finally, the selection of the lter device was left up to the discretion of the
physician, such that four different lter types were used
in the trial.
35
Despite these weaknesses, the PREPIC study
highlighted the fact that permanent IVC lter placement
carries certain risks that could potentially be avoided with
lter removal.
Expanding on the results of the PREPIC trial, the
PREPIC2 trial focused only on optional retrievable lters
utilized over a narrow therapeutic window. In this study,
398 patients were randomized to receive either 6 months of
anticoagulation alone or anticoagulation and an IVC lter.
Those randomized to the lter group had the lter removed
after 3 months and then received an additional 6 months
of anticoagulation. At 3 months, there was no signicant
difference in incidence of PE (3% with lter vs 1.5% with
no lter, P=0.50), and at 6 months, there was no signicant difference in mortality, PE, or recurrent DVT between
the two groups.
36
The authors concluded that the use of
retrievable IVC lters in addition to anticoagulation offers
no benet over anticoagulation alone.
The PREPIC2 study design was improved over the
original PREPIC trial in that anticoagulation and lter
type were standardized. However, the trial again failed
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to address the potential benet of IVC lters in the
population for which they are most frequently utilized:
patients with VTE who cannot be anticoagulated. Furthermore, the study was not designed to address the issue
of whether lter retrieval offered improved morbidity
and fewer complications over permanent lter placement,
since there was no study arm that included permanent
lter placement. Additionally, the 6-month study period
was not long enough to provide sufcient data for evaluating rates of recurrent DVT after retrieval; thus, nothing
can be inferred from the data regarding the incidence of
recurrent DVT at this time.
The retrospective data available comparing permanent and optionally retrievable devices is equivocal at
best. A cohort study of 702 patients found similar rates
of recurrent PE in patients who received both permanent
and optionally retrievable lters, suggesting that both types
of lters are similarly effective. While no difference in the
incidence of recurrent DVT was noted, the mean follow-up
in this study was only 11.5 months, and only 15.5% of
the optionally retrievable group had the lters removed.
37
While optionally retrievable devices likely offer protection
from PE that is similar to permanent lters, it is unclear
whether early retrieval offers any improvement in complication rate. In fact, there is some concern that optionally
retrievable lters may be prone to higher device failure
rates. In 2010, the FDA released a safety communication
stating that from 2005 to 2010, over 900 adverse event
reports were received, including IVC perforation, lter
migration, lter fracture, and component embolization.
The FDA statement, which was updated in 2014, recommended removal of retrievable lters as soon as protection
from PE is no longer required. Asubsequent analysis of the
FDA Manufacturer and User Facility Device Experience
(MAUDE) database supported this statement, noting a
signicantly higher number of adverse events reported for
retrievable lters compared to permanent lters from 2009
to 2012.
lters were found to have a greater predictive effectiveness
and lower cost compared to retrievable lters.
38
Additionally, using a Markov model, permanent
39
In summary, optionally retrievable lters offer similar
benets to permanent lters and in general are associated
with low morbidity. The selection of a permanent or an
optionally retrievable lter should be considered on a caseby-case basis. Given the concern for a higher device failure
rate, patients who receive an optionally retrievable device
should have appropriate follow-up, and the lters should
be removed as soon as safely allowable. Optionally retrievable lters should only be considered in certain populations, including younger patients, patients with temporary
contraindications to anticoagulation, and for prophylactic
indications.
Though convertible lters lack long-term data, their
utility needs to be considered. Bioabsorbable lters provide
protection from PE for roughly 5 weeks and are adsorbed
by 6 months
28
and may be a good option for patients without reliable follow-up. However, absorbable lters lack the
ability to provide long-term protection. Convertible lters
offer the option to easily convert to an open conguration, but those lters that were not converted had a fairly
high rate of IVC occlusion, so this is not a good option for
patients without an anticipated conversion plan.
30
28.9 TECHNIQUES OF IVC FILTER
PLACEMENT
Placement techniques for each of the lters differ, and the
most appropriate step-by-step guide for placement can be
found in the operator’s instructions provided by the manufacturers. These directions should be reviewed prior to
placement and followed carefully to ensure the safety of
the patient. The usual steps involved in percutaneous lter
placement are described in Table28.5.
28.9.1 Venous access
The choice depends on the patency of the vein access site
and sometimes operator preference. The right common
femoral vein is the most common access site and affords a
relatively straight course to the IVC. This is the preferred
access site unless there is evidence of a clot in the right femoral or iliac veins. The right jugular vein is another common access site through which most of the available lters
can be deployed. Left femoral, jugular, antecubital, and
more recently popliteal veins have all been used depending on the anatomy and type of the lter that is planned
to be deployed. Placement of IVC lters through the left
femoral and jugular approaches have been associated with
a greater incidence of lter “tilt” with respect to the course
of the IVC. Filters with low-prole delivery systems such as
the TrapEase and Simon nitinol lters (6 Fr) can be placed
via the antecubital vein.
described and are limited only by the surgeon’s or interventionist’s ingenuity. For example, the authors have placed
Simon nitinol lters through the right greater saphenous
vein in morbidly obese patients and Günther Tulip lters
through a brachial approach with success in patients with
bilateral femoral and jugular thrombosis.
TABLE 28.5 Steps involved in radiological inferior vena
cava lter placement
1. Preprocedural evaluation:
• Review indication and risk versus benets of inferior vena
cava (IVC) lter placement, including the duration for
which the lter is likely to be needed
• Review available duplex ultrasound/computed tomography/magnetic resonance imaging to evaluate presence of
IVC, iliac, or femoral vein thrombus
• Evaluate coagulation status
2. Preparation for lter placement:
• Choose access based on the previous evaluation
• Perform inferior venacavogram; evaluate for IVC thrombus; identify level of renal veins; measure IVC diameter;
detect venous anomalies
3. Choose the appropriate lter and deploy according to operator’s instructions provided by the manufacturer
4. Perform postdeployment radiographs
5. Follow-up recommendations
40
Alternative access sites have been
28
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28.9.3 Intravascular ultrasound
and transabdominal duplex
ultrasound-guided placement of
IVC filters
Bedside placement of IVC lters by using either transabdominal duplex or intravascular ultrasound (IVUS) guidance has been shown to be safe and effective.
techniques are preferred and are especially useful in critically ill patients, those who are pregnant, those who have
a contraindication to iodinated contrast media and CO
not available, or those who exceed the safe weight limits of
standard radiographic equipment.
28.2 Inferior venacavogram performed prior to inferior vena
cava lter placement showing normal caliber of the inferior vena
cava and location of renal veins. (
gram using iodinated contrast media in digital subtraction mode
and with bone landmarks to facilitate inferior vena cava lter
placement.
the contrast medium in a patient with renal insufciency.
(c) Inferior venacavogram using carbon dioxide as
a and b) Inferior venacavo-
28.9.2 Inferior venacavogram
Either iodine-based contrast or carbon dioxide is used to
obtain a venogram via a marking pigtail catheter (Figure 28.2). A venacavogram is used to identify venous
anomalies, measure caval diameter, exclude thrombus
in the IVC, and identify the level of the renal veins. The
opacication of the renal veins may be enhanced by the
Valsalva maneuver. Except for the bird’s nest and VenaTech low-prole lters, most of the commercially available
lters are recommended for IVC diameters of 30mm or
less. When placing a lter in a patient with a megacava,
two options for treatment exist: placement of a bird’s nest
or other lter type that is approved for a large vena cava
or placement of bilateral common iliac vein lters with
devices that are approved for a vena cava of 28 mm in
diameter or less.
Three major venous anomalies are of particular interest
when placing an IVC lter. These are duplication of the
IVC, circumaortic left renal vein, and left-sided IVC. These
anomalies must be assessed prior to placing an IVC lter.
Duplication of the IVC is seen in 0.2%–3.8% of the population and occurs due to persistence of both right and left
cardinal veins. The cavae may be of equal size, although
the right cava is usually larger. The left cava joins the right
at the level of the left renal vein. This IVC variant can be
safely excluded if contrast lls the left iliac vein on cavogram. If the left iliac vein is not seen on venogram and the
left renal vein appears prominent, then a duplicated IVC
should be actively ruled out prior to lter placement. If a
duplicated cava is identied, then two options exist: two
lters may be placed in both cavae or a suprarenal lter
can be placed. Acircumaortic renal vein occurs in 8.7%
of the population, and the posterior component of the left
renal vein is usually lower than the anterior one. The lter
should be placed below the entry of all renal vein branches.
Left-sided IVC is rare, with a prevalence of 0.2%–0.5%.
The left cava crosses at the level of the renal vein to the
right side, and the lter is deployed in the infrarenal location in such patients.
28.9.4 Transabdominal duplex ultrasound
technique
Transabdominal duplex ultrasonography is performed to
determine the technical feasibility of bedside lter placement. Important ndings to be noted on preprocedural
ultrasound include IVC diameter, absence of venous
thrombosis, absence of venous anomalies, and the patency
of the intended femoral vein access site. The IVC must be
adequately visualized at the renal vein junction in both the
transverse and the longitudinal axes. Identication of the
right renal vein is critical because this usually represents
the lowest renal vein. If venous anomalies or iliofemoral venous thrombosis is suspected, contrast venography
is preferred to dene the venous anatomy more precisely
before lter placement.
The procedure is usually performed under local anesthesia. The femoral vein access is obtained and a 0.035-inch
guidewire is advanced into the IVC. The lter introducer
sheath is advanced over this wire to just above the renal
vein conuence. The guidewire is removed to enable adequate visualization of the tip of the delivery catheter. The
lowest renal vein/IVC junction is visualized transversely
as the lter delivery catheter and sheath are slowly pulled
back. When the tip of the lter delivery catheter disappears
from the ultrasound view, the intended deployment position has been reached. This is visualized on longitudinal
view, and under direct visualization, the lter is deployed.
Full deployment is conrmed with dedicated duplex imaging and plain abdominal radiographs.
28.9.5 IVUS technique
Under local anesthesia, femoral vein access is obtained and
a 9-Fr (longer than 25cm) sheath is placed into the IVC
over a 0.035-inch guidewire. An IVUS probe (15 MHz) is
inserted over the guidewire to the level of the right atrium.
With pullback technique, the level of renal veins, caval
diameter, caval anomalies, caval thrombosis, and conuence of the iliac veins are identied. If the conuence of
iliac veins is not clear, contralateral femoral vein access
is obtained and IVUS is performed again to identify the
previous venous landmarks. Single or dual venous access
techniques can be used for lter placement.
In the dual venous access technique, the IVUS probe
is positioned just below the renal veins. Filter deployment
is performed through a separate venous access, preferably
41,42
These
is
2
28.11 Complications of IVC filters 289
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through the contralateral femoral vein to reduce the incidence of access site thrombosis by dual puncture at a single common femoral vein. The lter delivery catheter and
sheath are inserted to a level above the renal veins and
pulled back to just below the renal veins. Correct placement
is then conrmed by IVUS. Once the position is conrmed,
the IVUS probe is pulled back and the lter is deployed.
In the single-vein, single-puncture technique, the IVUS
probe is removed after the vein anatomy is interrogated.
The length of the IVUS probe is then premeasured against
the length of the lter delivery catheter that corresponds to
the position of the lter delivery catheter when fully loaded
in the sheath. Measurement guides on the IVUS probe
mark this distance. The IVUS probe is then inserted into
the sheath up to this premeasured length, which represents
the distance that the lter delivery catheter extends beyond
the length of the sheath. The IVUS probe and sheath are
pulled back together to a level just below the lowest renal
vein as visualized by IVUS. In this regard, IVUS is guiding sheath positioning, which, because of the premeasured
length, indirectly guides the intended lter position. Finally,
the IVUS probe is removed, the lter delivery catheter is
loaded into the sheath, and the IVC lter is deployed. Postprocedure abdominal X-rays are obtained to conrm the
placement, position, and alignment of the lter.
28.10 FOLLOW-UP OF IVC FILTERS
Patients with vena caval lters should undergo follow-up
on an annual basis until removed if retrievable, and indefinitely if permanent. The purpose of the examination is to
evaluate the mechanical stability of the lter. In addition,
the condition of the lower extremities is evaluated to monitor the ongoing risk for recurrent thrombosis. Because
so many of these devices are placed by radiologists, it is
important that the information about the lter placement
is passed along to the patient’s local physician so that
arrangements for the appropriate studies can be made.
Patients with optionally retrievable lters placed for
temporary risk of PE should be followed more rigorously.
Although the recommended retrieval window varies by
device, the FDA issued a safety statement in 2010 and again
in 2014 recommending that retrievable lters be removed
as soon as protection from PE is no longer required. These
patients should be reassessed at 1- to 3-month intervals
after lter deployment to determine whether ongoing protection from PE is warranted. Astandardized surveillance
program is highly recommended, as patients are otherwise
much less likely to have the lter removed when appropri-
43,44
ate.
Traditionally, follow-up after IVC lter placement has
included physical examination of the lower extremities to
observe for edema, hyperpigmentation, skin ulceration,
and other signs of post-thrombotic syndrome. In the past,
anteroposterior and lateral radiographs of the lter were
obtained at intervals and compared to previous studies
for IVC lter follow-up to demonstrate the mechanical
stability and physical integrity of the device. This practice
is currently controversial, as the long-term complications
of established IVC lters are low. Newer lters, with less
long-term data on fracture and migration rates, may be
candidates for this more rigorous follow-up until these
issues are rmly resolved.
Emergent follow-up should be obtained if the patient
develops new bilateral lower extremity edema. Should this
occur, a duplex scan of the vena cava is performed to look
for thrombus in the lter or IVC. If the results of the ultrasound study are indeterminate, the patient should undergo
a venacavogram to evaluate for caval obstruction. If occlusion is documented and felt to be of recent origin, and the
patient’s medical condition allows, thrombolytic therapy
may be attempted in order to treat the current symptoms
and prevent later post-thrombotic syndrome. Patients who
present with signs or symptoms of PE should also undergo
venacavogram to determine the patency of the lter and
the presence of trapped or propagating emboli. Rare propagation of thrombus above the level of the lter may be
an indication for a second (suprarenal) lter rather than
thrombolytic therapy.
28.11 COMPLICATIONS OF IVC
FILTERS
Complications of IVC lter placement include those related
directly to the procedure for placement or removal and
those related to the length of time the lter stays inside the
43
The incidence of complications varies and depends
IVC.
not only on lter type but, more importantly, also on the
methods used to assess complications and the duration
of follow-up. Table28.6 lists the common complications
associated with IVC lter placement. Fortunately, most of
the complications associated with IVC lters are minor
or infrequent. Access site thrombosis is the most common
complication. With newer, smaller-sized delivery systems,
the incidence of occlusive thrombosis of the access vein
TABLE 28.6 Complications of inferior vena cava lter
placement
Complication Incidence (%)
1. Procedure-related complications:
• Puncture site complications: bleeding,
infection, thrombosis, or air embolism
• Delivery system complications: lter malposition, tilting, or incomplete opening
• Inferior vena cava wall penetration
• Death
2. Filter migration to renal vein, heart, or pulmonary artery
3. Filter fracture <1
4. New or worsened deep venous thrombosis 6–30
5. Inferior vena cava thrombosis 6–30
6. Recurrent/fatal pulmonary embolism 2–5
7. Venous insufciency 10–30
Abbreviations: Minor degrees of filter migration are of little concern. However, filter migration to the heart or pulmonary artery may be fatal due to
the development of associated arrhythmias, acute myocardial infarction,
pericardial tamponade, and cardiac valvular injury. Percutaneous retrieval
or repositioning can be performed in these situations in an attempt to avoid
emergent thoracotomy.
4–11
3–69
28
290 Chapter 28 Indications, techniques, and results of inferior vena cava filters
https://t.me/med1917
is low (2%–10%), although a nonocclusive femoral vein
thrombus is seen more often (25%). IVC thrombosis is a
serious and potentially fatal complication requiring emergent diagnosis and treatment. Thrombus may extend above
the level of the lter, causing major PE and necessitating
placement of an additional lter in the suprarenal IVC.
IVC thrombosis may also cause phlegmasia cerulea dolens,
a limb-threatening condition. While small clot burden may
be treated with anticoagulation, large-to-complete caval
thrombosis causing symptoms may need thrombolysis or
stent placement in the IVC to restore patency and treat
associated phlegmasia.
28.12 COMPARISON OF PERFORMANCE
BETWEEN IVC FILTERS
Despite large numbers of clinical studies describing the
effectiveness and safety of IVC lters, there are no studies
that prospectively compare different lter designs.
IVC lters have been shown to be efcacious at preventing PE irrespective of lter design; however, comparing
different designs is difcult due to variations in the populations studied, evaluation criteria, associated treatments,
and the types and durations of follow-up.
eral guidelines have been published concerning reporting
standards for lters.
46,47
Patient outcomes related to the
Greeneld lter have been extensively documented, culminating in 27years of experience with the stainless steel
and the titanium Greeneld lters. In all, the patency rate
has remained at 96% and the rate of recurrent PE has
been between 3% and 5%.
25
Other comparative studies
focus more on the difference in complications between
lter designs. A systematic review on 24 different lters
was based on the SIR classication of complications; fracture, insertional problems, IVC perforation, and migration. Fracture rates were found to be highest in the early
conical Bard devices at just under 40% at 60 months in
the retrieval and G2 series. The Cordis OptEase/TrapEase
also had fracture rates nearing 50%. In terms of insertion
45
Therefore, sev-
issues, tilt >15 degrees was most common in conical lters,
ranging from 2.3% to 58%, and wire prolapse was noted
in the Cook bird’s nest lter in up to 70%. IVC perforation was the highest in purely conical lters, ranging from
22% to 93% in retrievable lters, and up to 85% strut
perforation in the bird’s nest lter. Migration was >10%
in the Bard recovery and G2 series, Greeneld titanium,
Cook Tulip, and VEnatech LGM lters. An IVC occlusion
was most common in lters with a cylindrical component
or umbrella component, with the OptEase/TrapEase lter
having rates of 28% and the Simon nitinol lter ranging
from 3.5% to 50%.
48
The comparative efcacies and com-
plications of different IVC lters are detailed in Table28.7.
28.13 SUPRARENAL IVC AND
SUPERIOR VENA CAVA FILTERS
Indications for suprarenal IVC lter placement are listed in
Table28.8. Recent data suggest similar outcomes of retrievable IVC lters placed infrarenally vs suprarenally.
49,50
The role of a superior vena cava (SVC) lter in preventing
PE is controversial. Afew reports have described the benets
of such lter placement.
51,52
SVC thrombosis and guidewire
entrapment during central line placement are potential complications. One recent systematic review reported serious,
life-threatening complications (including SVC perforations,
cardiac tamponade, aortic perforation, and recurrent pneumothorax) in 3.8% of SVC lters deployed. The rates of PE
and associated mortality in patients with upper extremity
DVT were 5.6% and 0.7%, respectively.
53
Therefore, the
risks associated with SVC lter placement may outweigh
any potential benets in PE prevention.
28.14 CONCLUSION
Vena caval lters provide protection against PE without the
signicant morbidity and mortality associated with surgical interruption. They are intended for use in patients who
TABLE 28.7 Performance of different inferior vena cava lters
Filter Number Mean follow-up
Stainless-steel Greeneld 3184 18 2.6 5.9 3.6 19
Titanium Greeneld 511 5.8 3.1 22.7 6.5 14.4
Stainless steel over-the-wire
Greeneld
Simon nitinol 319 16.9 3.8 8.9 7.7 12.9
Bird’s nest 1426 14.2 2.9 6 3.9 14
VenaTech/LGM 1050 12 3.4 32 11.2 41
Low-prole VenaTech 30 2.3 0 10.3 0 Not reported
TrapEase 65 6 0 45.7 2.8 Not reported
Günther Tulip 83 4.5 3.6 Not reported 9.6 Not reported
Source: Angel LF etal. J Vasc Interv Radiol 2011;22(11):1522–30.e3; Hann CL and Streiff MB. Blood Rev 2005;19(4):179–202.
(months)
599 26 2.6 7.3 1.7 2
Recurrent
pulmonary
embolism (%)
Deep venous
thrombosis (%)
Inferior vena cava
thrombosis (%)
Post-phlebitic
syndrome
References 291
https://t.me/med1917
TABLE 28.8 Indications for suprarenal inferior vena cava
lter placement
• Anatomic variants (i.e., duplicated IVC)
• External compression or IVC compression (i.e., during pregnancy)
• Renal vein or infrarenal vena cava or ovarian vein thrombosis
• Thrombus propagating proximally to a previously placed lter
in an infrarenal location
the prophylaxis of PE in patients with time-limited contraindications to anticoagulation; however, recent societal
guidelines largely recommend limiting IVC lter use when
anticoagulation is possible. The type of lter used should
be tailored to each patient, with particular attention paid
to the indication and the long-term results associated with
the IVC lter chosen. The recent increase in the use of
retrievable IVC lters is notable, and additional studies are
required to document their safety and efcacy.
As improved techniques for the delivery of these devices
are at risk of PE but for whom anticoagulation is contraindicated or thought to be insufcient. IVC lter placement
is a technically straightforward and safe procedure with
an associated low morbidity and mortality. Multiple studies have demonstrated the efcacy of lters for preventing
PE, although rarely IVC lters may cause progression or
recurrence of DVT in lower extremities and IVC thrombosis. The rates of these complications are device specic,
and it is important for physicians placing IVC lters to be
familiar with the thrombosis, migration, and complication
rates associated with the lter chosen for placement. There
has been a surge in the placement of retrievable lters for
and new materials and designs are developed, it is essential to keep in focus the indications and appropriate uses
of these devices, including retrievable lters. Rather than
focusing on the differences between the various devices
(which will sort themselves out over time), the major effort
ought to be directed toward identifying those patients
who are at highest risk of signicant PE. Efforts must also
continue to be directed toward improving methods of
thromboprophylaxis, since no lter can inuence the development or course of the underlying disorder. This is clearly
a case in which a well-planned offense is the best defense
against this unnecessary source of morbidity and mortality.
Guidelines 28.0 of the American Venous Forum on the indications, techniques, and results of inferior vena cava lters
No. Guideline Grade of
28.1 We recommend placement of inferior vena cava (IVC) lters: in patients with deep
venous thrombosis (DVT) and/or pulmonary embolism (PE) and a baseline contraindication to anticoagulation; in patients who suffer a complication from anticoagulation;
in patients who develop recurrent DVT or PE despite adequate anticoagulation; and in
patients who previously have had a massive PE and cannot tolerate further cardiopulmonary insult that would be associated with an additional PE.
28.2 We suggest placement of an IVC lter in patients with a free-oating thrombus greater
than 5cm in length within an iliac vein or the IVC.
28.3 We suggest prophylactic lters to patients if their associated medical conditions (malignancy or traumatic injuries) predispose them to DVT or PE.
28.4 We suggest caution in special situations prior to lter placement for patients with untreated or uncontrolled bacteremia, pediatric patients, and pregnant women, due to the
uncertain long-term effects and durability of the lters.
28.5 We suggest bedside placement of IVC lters by using either transabdominal duplex or
intravascular ultrasound guidance. Both have been shown to be safe and effective.
28.6 We suggest performing additional studies to document the safety and efcacy of the
placement of retrievable lters in patients with time-limited contraindications to anticoagulation.
28.7 We suggest follow-up examination annually for patients with vena caval lters to evaluate the mechanical stability of the lter. In addition, the condition of the lower extremities is to be evaluated to monitor the ongoing risk for recurrent thrombosis.
recommendation
1
(strong)
2
(weak)
2
(weak)
2
(weak)
2
(weak)
2
(weak)
2
(weak)
Quality of
evidence
A
(high)
B
(moderate)
B
(moderate)
C
(low to very low)
B
(moderate)
B
(moderate)
B
(moderate)
28
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