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45.
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TEMPORARY FILTERS AND PROPHYLACTIC
INDICATIONS
Robert B . Rutherford , John C. McCallum , and Nikhil Kansal
ince the development of retrievable vena cava lters
(RVCFs), their use for prophylactic indications has
S
contributed to the trend of increasing inferior vena
cava (IVC) lter use for patients at risk for venous thromboembolic disease. Apreceding chapter has dealt with permanent lters, whose indications and results are relatively
well established, but recently a number of temporary or
retrievable lter devices have been introduced, and their use
is also increasing. In certain respects two of these upward
trends, in prophylactic indications and the use of RVCFs,
are linked in that both are most commonly used in dealing
with patients who have not had a pulmonary embolus (PE)
but who are considered to be at high risk of this dreaded
complication, yet only for a limited period of time. is
chapter will appraise both of these burgeoning practices,
and the available evidence regarding these remarkable shi s
in the use ofVCFs.
THE RATIONALE BEHIND
THE USE OF TEMPORARY OR
RETRIEVABLEVCFS
e preceding chapter dealt with the complications of vena
cava lters, which, it will be seen, provide part of the justi cation for using temporary or retrievable lters (RVCFs).
e justi cation for using RVCFs is based on two o -related
circumstances:(1)the risk of PE is limited in duration in
a number of patient categories and (2) the complications
associated with leaving a VCF in situ can be signi cant over
time. e latter consideration is particularly pertinent in
otherwise healthy younger patients with an extended longevity outlook who would be at risk of these problems for
manyyears.
is was just a theoretical position until a randomized
prospective trial suggested that this was indeed the case. e
PREPIC trial (Prevention du Risque d’Embolie Pulmonaire
par Interruption Cave) has been widely quoted as evidence
to support the use of RVCFs. is trial randomized
400patients with proximal deep venous thrombosis (DVT)
and a variety of indications for VCF placement into no lter
and lter groups, both receiving heparin (contraindication
to anticoagulant [AC] therapy was not represented). e
choice of lter used was optional and included Vena Tech
LGM, Titanium Green eld, Cardial, or Bird’s Nest. A er
12 days, there was a signi cant protection against PE by
the lters (1.1% vs. 4.8%, p=0.03) and a very suggestive
advantage against fatal PE (0.0% vs. 2.0%, p=0.12). At two
years, the protection against PE (3.4% vs. 6.3%, p=0.16)
and fatal PE (0.5% vs. 2.5%, p=0.21) appeared to persist,
but statistical signi cance was lost because of diminishing
numbers of patients. However, at two years, there was a signi cantly higher rate of DVT among the lter group (21%
vs. 12%, p=0.02). e conclusion was that although lters protected against PE, they carried a higher risk of later
DVT. Whether this late DVT risk was related to the thrombogenicity of some of the lters used, and/or associated
caval thrombosis due to disturbed ow or intimal changes
is not known, and the results were not analyzed relative to
lter type. Follow-up data at 5 and 8years showed the same
trends in terms of DVT, but statistical signi cance, though
close, was lost (p=0.06 at ve years and p=0.08 at eight
years).
Some have used these late follow-up data to claim that
there is not a long-term risk of DVT associated with leaving in VCFs, whereas others have countered that the trends
are still clear but that, like many long-term studies, the loss
of patients to follow-up undermines statistical signi cance.
Nevertheless, this study added great impetus to the development of temporary, retrievable lters for prophylactic indications representing a limited duration of riskofPE.
Most recent data regarding outcomes from RVCF are
derived largely from single-institution, observational case
series. ere is little randomized controlled data. Arecent
Cochran Review
other trial met consideration for inclusion and analysis in a
1
found that the PREPIC trial and one
378
review of randomized controlled trials looking at the e ec-
https://t.me/med1917
tiveness of vena cava lters in preventing pulmonary embo-
2
lism. In the other trial, Fullen etal.
found that cava lters
were e ective in reducing PE relative to controls without
lters in 129 patients, however the patient population was
noted to have a high rate of atherosclerotic heart disease and
heart failure, and no di erence in mortality wasnoted.
With the exception of these studies, which compare permanent lters to no lter, these authors are not aware of a
randomized controlled trial of RVCFs versus no lter, nor
of RVCFs versus permanent lters.
C U R R E N T L Y A V A I L A B L E R V C F S
It is not the purpose of this chapter to compare individual
lters (Figure 45.1). Nevertheless, speci c lters will be
mentioned in the discussion that follows; therefore they
should be identi ed here. Currently available RVCFs that
have been approved by the FDA for use in the United States
include the Günther Tulip (Cook), the Celect (Cook), the
OptEase (Cordis), the Option (Rex Medical), the Meridian
(Bard), and the Eclipse (Bard). Meridian and Eclipse are new
marketing names for the second-generation Bard RVCF.
Bard’s RVCF was initially marketed as the “Recovery” lter, then signi cant changes were made it its design including increased numbers of struts, leading to the “G2” device.
Subsequent names for this second-generation device include
the “G2x,” and both the “Meridian” and “Eclipse” products
are based on the second-generation “G2” body, with minor
changes (personal communication with the manufacturer).
PROBLEMS WITH
CURRENTRVCFS
In spite of the impressive technological advances associated
with the development of RVCFs, there are still a number of
limiting factors that must be pointed out. Removal of many
if not most of the current temporary lters becomes increasingly di cult with passage of time because of thrombus in
the lter and/or adherence at points of endothelial contact.
As a result many have simply been le in. rombus in a
lter can be interpreted as good (a potential PE has been
trapped) or bad (device thrombogenicity). is problem
in retrieving temporary lters may have resulted in renaming them optional lters, meaning that they can be used as
either temporary/retrievable lters or le in as permanent
lters. is implies that it is quite permissible (i.e., no signi cant penalty) to leave them in. is name change may
be a marketing ploy because, as of this writing, no good
long-term outcome data on these new optional lters has
been published to justify leaving them inde nitely (e.g.,
low rates of recurrent PE, lter migration, lter or caval
thrombosis, distal DVT, etc.). Instead, a growing body of
literature suggests that complications persist over time and
lters should be removed as soon as the indication for their
placement has ceased to be applicable.
Since 2007, a number of retrospective studies have been
published that report extending dwell times for RVCFs,
periods of time that the lters can be le in place and still
be successfully removed. Table45.1 includes data for recent
reports on successful retrieval rates of RVCFs, mean dwell
times, as well as range of time in place. While several studies report lters being le in place for over a year, no case
3
series reports an average dwell time over 200days.
Filter
tilt, incorporation of lter struts into the walls of the vena
cava by endothelialization, and the presence of a signi cant amount of trapped thrombus have been reported as
the major pathophysiologic processes that increase the dif culty of lter removal. As endovascular specialists have
increased their experience with removing vena cava lters,
their ability to remove what were previously thought to be
technically irretrievable lters has improved. is is demonstrated in the technical success rates seen among attempted
lter removals in Table45.1, which range from 78–100%,
despite increasing dwelltimes.
e reported experience with the greatest claim regarding safe dwell time before a RVCF is removed has been with
the Günther Tulip, which demonstrated the feasibility of
retrieval at 494days, with a range of 3–494days and a mean
3
of 58.9days, in a case series by Smouse etal.
ey report
technically successful removal in 248 of 275 attempts (90%)
to remove lters, among 554 patients in whom retrievable
lters were placed, thereby representing a 44% removal
rate among all lters placed. ey report that “unsuccessful attempts (n=27) were attributed primarily to improper
hook orientation (n=10), or excessive tissue in-growth at
the lter legs (n=16).” ey did not report accumulated
thrombus as a major reason for inability to remove lters.
ey provide a breakdown of successful retrieval attempts
over time via a Kaplan-Meier analysis, and report successful
retrieval of greater than 99% at 4 weeks, greater than 94%
at 12 weeks, greater than 67% at 26 weeks, and greater than
37% at 52weeks.
e case series reporting the claim regarding the greatest
safe average dwell time involved the Celect lter, the succes-
6
sor to the Günther Tulip. Lyon etal.
reported removal at
an average of 179days, with a range of 5–466days among
95 patients, with a successful removal rate of 96.6% ey
reported 100% successful retrieval at 50 weeks, and 74% at
55 weeks, representing 9 patients with lters removed a er
52weeks.
With reports of lters le in place for several months
at a time with predictable retrieval rates, the practice of
repositioning lters, once thought to extend the dwell time
while enabling retrievability, is moving into disuse. Neither
Smouse etal. nor Lyon etal. repositioned lters, and still
reported the longest dwell time of a lter to these authors’
3,6
knowledge.
Areview by Berczi etal. 14 concluded that “the
TEMPORARY FILTERS AND PROPHYLACTIC INDICATIONS • 379
Table45.1 CLASSICAL COMPLICATIONS AND DEVICE RETRIEVAL RATES PERCENTAGES COMPLETED
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STUDY TOTAL
NUMBER
OF FILTERS
PLACED
STUDY
TYPE
FILTER
TYPE
FOLLOWUP
DURATION
MONTHS
PE NUMBER
%
DVT IVC
OCCLUSION/
THROMBOSIS %
SUCCESSFUL
RETRIEVALS/
ATTEMPTED
RETRIEVALS %
MEAN DURATION
BETWEEN PLACEMENT AND
SUCCESSFUL RETRIEVAL
RANGE DAYS
Given etal. 4 322 PO GT NR 1 (<1%) NR NR 188/205 (92%) 76.95 (1–309)
5
Johnson etal.
Lyon etal.
Sangwaiya etal.
Cantwell etal.
9. Charles etal.
Smouse etal.
Hammond etal.
Ziegler etal.
Onat etal.
Oliva etal.
Key:PO, prospective observational; RO, retrospective observational; GT, Günther Tulip; Cel, Celect; Rec, Recovery; NR, not reported.
Table45.1 represents recent data related to classical outcomes as measured forRVCFs.
In addition to these outcomes, the widespread use retrievable lters has highlighted additional concerns about complications including lter fracture, migration, tilt, malposition, and IVC perforation. e rates of these are
reported in Table45.2.
100 PO Option 6 8 (8%) 18 (18%) 3 (3%) 36/39 (92%) 67.1 (1–175)
6
95 PO Cel 12 1 (1%) 1 (1%) 0 (0%) 56/58 (97%) 179 (5–466)
7
73 RO Cel 2 2 (2%) 1 (1%) 0 (0%) 14/15 (93%) 84 (5–381)
8
241 RO Rec, G2 25 5 (2%) 0 (0%) NR 127/133 (95%) NR
9
140 RO G2 NR NR NR NR 26/26 (100%) 122 (11–260)
3
554 PO GT NR 3 (<1%) NR NR 248/275 (90%) 59 (3–494)
10
317 RO GT, others NR 2 (<1%) NR 10 (3%) 100/128 (78%) NR
11
150 PO OptEase 6 0 (0%) 1 (<1%) 4 NR NR
12
228 RO OptEase 6 (3%) NR 1 115/124 (93%) 11 (4–23)
13
27 PO OptEase 1 0 (0%) 1 (4%) 0 21/21 (100%) 11.1 (5–14)
original implantation time of 10–14days has been extended
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to more than 100days as the mean implantation time” for
many lters.
While these studies suggest that removal of an RVCF
is technically possible at a longer period of time than previously thought, the proportion of patients in whom retrieval
is attempted remains small. is is reportedly due in large
part to ongoing contraindications to anticoagulation and
the need for prevention of PE, as well as loss to follow-up.
Arecent study from the trauma literature by Rogers etal.
15
reported that a concerted e ort involving phone contact,
patients’ family members, rehabilitation facilities, and social
workers was able to achieve a 59% retrieval rate among lters that could have been removed.
In summary, successes with predictably removing RVCFs
at greater than 100days has expanded their application to
the point where a retrievable lter is more likely to placed
for a temporary indication than is a permanent lter. e
longer dwell times with subsequent safe removal has moved
the eld away from a previous paradigm of serially repositioning the lter to promote retrievability.
PROPHYLACTIC
INDICATIONS:CRITICAL
APPRAISA L
e major and steady increases in the use of prophylactic
indications over the last three or four decades, to the point
where it clearly dominates over therapeutic indications, have
a number of likely reasons, but because all the conditions for
which VCFs are being applied were all present by the time
e ective permanent VCFs were available, in the late 1960s,
it seems appropriate to question the justi cation for such
a large increase, particularly since there does not appear to
be good data-based evidence for most prophylactic indications. Some general statements can be made about prophylactic indications in some respects, but in other respects it
is necessary to focus on individual categorical prophylactic
indications to pinpoint key issues.
CHANGES IN REFERRAL PATTERNS
AND SPECIALIST PERFORMING THE
PROCEDURE
e placement of VCFs, in the period a er well-designed permanent devices were developed and available, was performed
through remote cut-down under general or local anesthesia
with sedation, with what was then an acceptably low procedural morbidity and mortality, the latter usually being
attributable to intercurrent disease rather than operative
misadventures. What percutaneous placement of the newer
low-pro le devices o ered was the avoidance of open surgery,
empirically attractive to referring physicians. Although vascular surgeons continued to participate in these trends and
introduce new technology and technical approaches, percutaneous placement increasingly opened the door to other
interventionalists (e.g., an interventional radiologist, cardiologist, or other specialist with catheter skills). In addition, the
referring physicians more o en were those without a primary
interest in the management of venous thrombo-embolish
(VTE) and AC therapy (e.g., an oncologist, trauma surgeon,
bariatric surgeon, orthopedic surgeon, neurosurgeon). is
combination of less knowledgeable, less critical physician
referrals and ready acceptance by service-oriented interventionalists may have played a major role in liberalizing the
indications for prophylactic VCFuse.
LACK OF ADEQUATE EVIDENCE
ON WHICH TO BASE DECISIONS
REGARDING VCFUSE
ese changing referring physician–interventionalist
arrangements may have resulted in not only an apparent
lack of critical appraisal of expanding indications but also a
dearth of critical outcome assessments. In a Medline search
of 568 references from 1975 to 2000 on VCFs, Girard
16
found that 65% either were retrospective studies
et al.
(33.3%) or case reports (31.7%), 12.9% were animal or in
vitro experiments, and only 7.4% were prospective studies.
Only 16studies involved more than 100 cases, and there
was only one randomized study. In contrast, 47.4% of 531
references on heparin in VTE were randomized prospective
trials. is is a striking contrast and should serve as a challenge to those involved with VCF placement to come up
with higher level data on which to base current practice.
R E C E N T O U T C O M E S D A T A
FROMRVCFS
Fracture, migration, tilt, malposition, and IVC perforation
have all been reported as complications of RVCF placement.
Nicholson etal. reported a high prevalence of fracture and
embolization with Bard “Recovery” ( rst generation) and
“G2” (second generation) lters: 13 of 80 patients had a
least one lter fracture (16%), and they reported ve cases
of fractured strut fragments embolizing to the heart, causing three patients to develop life-threatening sequelae.
Most of these events occurred with the rst-generation
RVCF, and were in part the impetus for the development of
the second-generation lter. e risk of embolization and
fracture has become evident with the passage of su cient
time to observe these rare risks. While other studies have
cited signi cantly lower rates of embolization and fracture,
these studies were not designed to detect such events and
may underestimatethem.
Filter tilt is reported in many of the studies listed in
3
Table45.2. Smousse etal.
report that 209 of 554 patients
were observed to have some degree of lter tilt, however they
do not report the degree of tilt nor the clinical signi cance
17
TEMPORARY FILTERS AND PROPHYLACTIC INDICATIONS • 381
Table45.2 FILTER FRACTURE, MIGRATION, TILT, MALPOSITION, AND IVC PERFORATION
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STUDY TOTAL
Nicholson etal. 17 80 Rec 38 (average) 13 NR NR NR NR
Smouse etal.
Hammond etal.
Oliva etal.
Ziegler etal.
Onat etal.
Johnson etal.
Lyon etal.
Sangwaiya etal.
Cantwell etal.
Charles etal.
Given etal.
Key:GT, Günther Tulip; Opt, Option; Cel, Celect; Rec, Recovery; Trap, TrapEase; NR, not reported.
13
12
6
95 Cel 12 0 0 40 (>5) 0 0
4
NUMBER
OF FILTERS
PLACED
3
554 GT NR NR NR 209 (any) NR 1
10
516 GT, others NR 1 NR 2 (any) 3 1
27 OptEase 1 0 0 0 0 0
11
150 OptEase 5 3 1 8 (>15) 1 0
228 OptEase NR 0 0 9 (NR) NR 0
5
100 Option 6 0 2 NR NR 0
7
73 Cel 2 1 1 4 (>15) NR 4
8
241 Rec, G2 25 9 41 36 (any),
9
140 G2 NR 0 1 5 (>15) 0 0
322 GT NR 1 1 NR NR 2
FILTER
TYPE
MEAN
FOLLOW UP
DURATION
MONTHS
of this nding. Among the authors cited in Table45.2, there
seems to be no consensus as to the degree of lter tilt that
is clinically signi cant, only that it contributes to retrieval
di culty in some cases and is seen commonly.
In a statement issued via their website, the FDA reported
that from 2005 to 2010, there were “921 device adverse
event reports involving IVC lters, of which 328 involved
device migration, 146 involved embolizations (detachment of device components), 70 involved perforation of
18
the IVC, and 56 involved lter fracture.”
e statement
did not di erentiate between permanent and retrievable lters, nor was there a quanti cation of the number of lters
placed from which this number of complications stemmed.
FILTER
FRACTURE
are generally considered to be reasonable prophylactic indications for inserting a VCF, but each subgroup deserves
clearer de nition. Severe, multisystem trauma is associated
with periods of hypercoagulability, and in some instances,
involves direct or indirect venous trauma or endothelial
damage. ese types of trauma are known to be associated
with a high risk of VTE, and AC therapy is usually contraindicated. Intermittent pneumatic compression (IPC) and/
or duplex surveillance (DS) is another prophylactic measure
to be considered, and IVC lter placement is appropriate
only when this is not practical or deemed e ective. It is
important to note that these patients need protection only
until they are ambulatory or AC therapy can be instituted.
e FDA went on to recommend that retrievable lters be
removed as soon as possible.
In summary, lter fracture, migration, tilt, malposition,
and IVC perforation have all been reported as complications of RVCF placement and retrieval. e rates and clinical signi cance of these events are not clearly de ned.
relates to the limited duration of the need for protection, it
is spurred by the fact that most trauma patients are young
and their expected longevity is great relative to the duration
of this need. Nevertheless, the duration of risk may be quite
long in many of these types of trauma relative to the safe
FILTER
MIGRATION
FILT ER TILT
DEGREE
11 (>15)
F I LT E R M A L
POSTITION
NR 0
PERFORATION
Although the justi cation for temporary caval ltration
indwelling time of most current retrievable lters. In such
ISSUES WITH INDIVIDUAL
PROPHYLACTIC INDICATIONS
Each prophylactic indication category deserves individual
comment in terms of VCFuse.
MultipleTrauma
Multiple long bone fractures, severe closed head injuries,
vertebral spine injuries with and without cord injury, pelvic or acetabular fractures, associated major direct venous
trauma, and essentially any other multiple system trauma
predicted to require extended period of immobilization
cases, with predictably long immobilization (e.g., spinal
fractures, pelvic fractures, multiple long bone fractures), it
might be better to use a permanent lter, the one with the
best long-term performance record.
VCFs have been reported to be e ective for this cate-
19
gory of prophylactic use. Langhan etal.
reported a 99.5%
e ectiveness but also reported a 12.8% rate of DVT a er
lter insertion, with an additional 10.3% in those followed
later. However, only 47% returned for follow-up (a problem with trauma patients), and the lter was visualized in
only 52% of those. On a survey questionnaire of the others,
twenty-seven had leg swelling, fourteen had other extremity symptoms, nine had shortness of breath, seven had chest
IVC
382 • VENOUS THROMBOEMBOLISM
pain, and four had venous skin changes. It cannot be deter-
https://t.me/med1917
mined, from such a follow-up, how many of these reported
problems could have re ected VTE. ere were three nonfatal lter complications, but all twenty-seven deaths were
attributed to the trauma, not the VCF. Clearly, the protection against PE was excellent but, much like the PREPIC
1
there appears to be a penalty for this approach in the
trial,
form ofDVT.
Better follow up has been achieved as mentioned ear-
lier by Rogers et al. through a program of “disciplined
15
follow-up.”
ey reported that among 7,949 trauma
admissions, 420 (5.2%) met criteria for lter placement,
and among those 160 were available for removal and 94%
were successfully removed(59%).
20
Rosenthal etal.
reported that for patients with multiple trauma, lters were successfully placed with 96.8%
technical success. None of the nineteen deaths was reportedly from VCF placement, and there were complications
in only 5.3%. One patient had a PE a er lter removal.
Follow-up in this study was short, and the incidence of
DVT was not documented. In another evaluation of this
21
approach from a trauma center, Duperier etal.
reported a
low rate of insertion complications in 133 consecutive multiple trauma patients, but “DVT was observed in 30% of
patients despite 92% being on prophylaxis”; 26% were de
novo. In this experience, the lter was inserted an average of
6.8 +/− 0.6 (SE) days a er trauma. In the previously cited
19
experience of Langhan etal.,
the mean insertion day was
6. is delay in insertion of the VCF in earlier trauma experiences, before the practice of bedside lter insertion under
ultrasound guidance, reinforces the potential value of this
relatively recent capability.
e American College of Chest Physicians Evidence Based
22
Clinical Practice Guidelines (8th edition)
enumerates
many concerns regarding a lack of solid evidence to support
prophylactic use of VCF in trauma patients. e authors
observe that prospective studies have shown no di erence
in the rates of PE among patients with and without prophylactic lters, and that lters are associated with shortand long-term complications, and may delay initiation of
proven e ective thromboprophylaxis. However they recognize that there is an indication for patient with a proven
proximal DVT and either an absolute contraindication to
full-dose anticoagulation or planned major surgery in the
near future. ey go on to encourage practitioners to implement therapeutic anticoagulation as soon as the contraindication resolves.
One critical appraisal of the prophylactic use of VCFs
in trauma patients has been recently been reported by
23
Knudsen etal.
In an analysis of 1,602 episodes of VTE
from the American College of Surgeons National Trauma
Data Bank, the authors observed that 90% had at least
one of nine accepted risk factors, and found the following
factors correlated signi cantly with outcome: age (>40),
lower extremity fracture, a high trauma score, head injury,
prolonged ventilator support (>3days), venous injury, and
major operative procedure. Eighty-six percent had prophylactic IVC lters placed, but 11% had no identi able risk
factors. ey concluded that (1)patients who need VTE
prophylaxis a er trauma can be identi ed by risk factors, and (2)the use of prophylactic IVC lters in trauma
patients should be reexamined.
Patients with Neurological Problems Resulting in
Paralysis or Prolonged Immobilization
Paralyzed or otherwise immobilized patients are at high
risk for VTE, but many can be managed by AC therapy.
In those in whom anticoagulants are contraindicated, if
the limbs are accessible (i.e., not injured or encumbered),
IPC and DS can be used, and may be e ective. ere are,
however, patients in whom AC therapy is contraindicated
or in whom the limbs are not accessible for IPC or DS (e.g.,
closed head or acute cord injuries associated with long bone
fractures) in which VCFs may be justi ed. Outside of this
exemplary exception, other forms of prophylaxis probably should be used with some form of surveillance for
DVTadded.
Several articles attest to this generic advice. Maxwell
24
studied 111 spinal cord–injured patients from a reg-
etal.
istry of 8,269 trauma admissions, and found that using these
other means of prophylaxis, there was an overall incidence
of DVT and PE of 9.0% and 1.8%, respectively, but with
no deaths. Mean hospital stay was 23days, and DS was performed an average of 2.3 +/− 2.1 times. e incidence of
DVT and PE with low molecular weight (LMW) heparin
alone was 11.1% and 2.8%, respectively, but when this was
combined with DS, it was only 7.4% and 0%, respectively,
so the latter combination was recommended. By comparison, in a subgroup with long bone fractures, the incidence
of DVT was 37.5%. ey concluded that IVC lters were
needed only in spinal cord injury patients with associated
long bone fractures, in those with detected DVT or its
progression under surveillance, or when AC therapy was
contraindicated.
Gorman etal.
spinal cord–injured patients who received prophylactic
VCF, eleven experienced DVT during their hospitalization,
relative to a comparison group of y-eight similar patients
who did not receive lters, among whom only three developed DVTs. ey went on to conclude that without other
indications for prophylaxis with VCF, SCI alone should
not precipitate prophylaxis withVCF.
is agrees with guidelines developed by a committee of
neurosurgeons
alone is insu cient and recommended rotating beds, IPC,
and DS in addition, with VCF inserted only if DVT was
detected. us, recent opinion appears to suggest that the
role of VCFs in this category should be limited to those
who develop DVT despite other forms of prophylaxis.
25
noted that among a group of y-four
26
who agreed that low-dose LMW heparin
TEMPORARY FILTERS AND PROPHYLACTIC INDICATIONS • 383
Patients with Advanced Malignancy
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Major Surgery Associated with a High RiskofDVT
Patients with advanced malignancy have been shown to be
at increased risk of VTE, and AC therapy may not be adequately protective. Prophylactic VCF use has been debated,
but the trend now favors therapeutic use (i.e., only a er
27
VTE). Risk factors have been identi ed.
Univariate analysis and logistic regression models identi ed the following as
signi cant risk factors for recurrent VTE:the appearance
of new metastases, a history of DVT, and neutropenia as a
result of chemotherapy. Other studies have identi ed stage
of disease and type of malignancy as speci c risk factors for
VTE. e e ectiveness of VCFs in preventing PE has not
in itself been challenged, but use of this indication for VCF
placement clearly must be balanced by patient prognosis
as demonstrated by three sobering reports. Jarrett etal.
28
reported on 116 patients with VCFs placed for advanced
malignant disease. Its e ectiveness was suggested by the
fact that two had recurrent DVT and three had PE a er
VCF, but it was the issue of patient survival that was challenged. Life table analysis showed survival to be 68% at
30days, 49.4% at 3months, and 26.8% at 1year. Of those
with stage IV disease, 46% died within 6 weeks and only
29
13.7% were alive at 1year. Damascelli etal.
reported 106
patients with malignancy in whom RVCFs were placed and
who were anticoagulated to a target international normalized ratio (INR) of 1.5–2.0. With a median follow-up of
217days, they reported only three PEs, all of these occurring in patients who had already had a PE. However, they
admit that “at the time of manuscript preparation, 44 of 106
patients were alive, 29 of them continuing with caval ltration combined with oral anticoagulation.” Shunn et al.
30
reported 97.5% protection against PE in forty patients
with advanced malignancy receiving VCFs, but also a high
(20%) complication rate. In addition, 30% survived less
than 30days. It is di cult to justify the use of a RVCF in
these patients. eir risk of thromboembolism is unlikely to
decrease during their lifetime.
Certain categories of major surgery have a predicted high
VTE risk, and yet the use of AC prophylaxis may be contraindicated or presumed ine ective. In such patients, VCF
has been felt to be indicated. Some well-known examples of
such VCF use include pelvic surgery, hip surgery, major surgery with history of DVT, major surgery with known or suspected hypercoagulable state, major venous reconstructions
with VTE risk, and gastric bypass surgery for morbid obesity. As a general criticism, in many of these applications, the
risk of VTE, the duration of risk, and the bene ts of VCFs
are poorly documented in the literature, and few studies
involve valid comparisons with alternative methods of prophylaxis. Nevertheless, it is clear that individual high-risk
patients can be identi ed, and when alternative methods of
prophylaxis are either contraindicated or ine ective, VCF
placement should be considered. As a general rule, in this
subcategory, an RVCF should be used if the patient can be
ambulatory or AC therapy can be instituted in about three
weeks, otherwise a permanent lter may be preferable. us,
although supporting data are scant, individual high-risk
patients can be reasonably chosen on their own merits, and
it is di cult to take exception with this practice.
Bariatric surgery has received much recent attention,
and although the intervention itself has been challenged by
many, some data and guidelines have emerged for prophylactic VCF use with this operation. Open gastric bypass for
morbid obesity carries a 1 to 4% PE risk in spite of other
methods of prophylaxis including IPC, LMW heparin,
and a push for early ambulation. Using RVCFs, Gariulo
reported a reduced PE rate in open gastric bypass for
patients with a BMI >55, but there was a 14% complication
rate. Factors associated with a high risk of VTE have been
32
identi ed
to include BMI >60, truncal obesity, venous stasis dermatitis, and hypoventilation/sleep apnea syndrome.
Logically, one would add those with a history of VTE and a
known or probable hypercoagulablestate.
31
Figure45.1 Examples of currently availableRVCF.
Günther Tulip
(Cook)
Celect
(Cook)
384 • VENOUS THROMBOEMBOLISM
OptEase
(Cordis)
Meridian
(Bard)
Similarly, Vaziri etal. 33 reported the use of prophylac-
https://t.me/med1917
tic VCF placement in thirty patients with a history of VTE
scheduled to undergo bariatric surgery. Patients underwent
a combination of open and laparoscopic procedures, and in
the patients deemed to be at high risk due to their history,
prophylactic VCF were placed a er induction of anesthesia and immediately prior to the bariatric procedure. At
follow-up ultrasonography on approximately postoperative day 19, six patients (21%) were noted to have recurrent DVT. Twenty-seven of the thirty patients underwent
follow-up venogram, and four patients (15%) were noted to
have signi cant thrombus trapped by the VCF. No patients
were discovered to havePE.
It has been said that this operation has a short, de ned
period of risk for VTE that is ideal for retrievable VCFs. On
the other hand, VCF placement can be challenging in morbidly obese patients, especially the superobese (BMI >60).
Duplex ultrasound guidance is impossible, but intravascular
ultrasound can be used to advantage in placing a lter in these
patients. In the face of great enthusiasm for this indication
for prophylactic VCF use, the author would insert a word of
caution:no prospective studies, comparing VCFs with alternative methods of VTE prophylaxis, have been carried out,
and most of the published reports related to its use have dealt
with open gastric bypass. It is quite conceivable that the laparoscopic approach, with its earlier ambulation, may signi cantly reduce the VTE risk. Whether this is su cient to allow
the adjunctive use of IPC and LMW heparin to be e ective
deserves investigation. In the meantime, the risk factors listed
earlier should serve as guidelines for selective VCFuse.
SUMMARY AND CONCLUSIONS
e current use of prophylactic indications for caval lter
placement and the RCVFs that have been developed for
this purpose have been reviewed. Based on this, some recommendations can be con dently made, but there is a clear
need better information, clarifying higher level studies on
which to base prophylactic indications. Also, there appears
to be room for further improvements in RVCF design, or
possibly the modi cation of an existing permanent lter
with good long-term outcomes so that it can be retrieved
if necessary. It may or may not be possible to design a truly
optional lter, one that can be retrieved as needed or le in
permanently without penalty. If not, the use of two types
of lters will persist as the best strategy—the best RCVF
and best permanent lter being chosen based on duration
of patient risk with safe indwelling time in the former.
Better supporting data are required to support either use.
It is also apparent that, in respect to categories of prophylactic indications, current practice is not based on a high
level of medical evidence and, in fact, the use of VCFs in
some of these settings appears to be excessive and subjectively determined. It is hoped that prophylactic indications
within each subcategory will be re ned in the future by
indication-speci c prospective analyses of critical outcome
data compared with alternative methods of prophylaxis, and
that these studies also will identify the factors signi cantly
a ecting outcome as a basis for more objective guidelines
for application. e need for evidence-based medicine here
is obvious. Industry-driven trials of single devices are not, in
themselves, acceptable for this purpose and tend to promote
excessive prophylactic use rather than control it. On the
other hand, if one believes in the potential of new technology to bring about continuing improvements, industry can
be expected to develop even better retrievable caval lters,
those which ultimately could be proven safe and e ective
for prophylactic use in patients temporarily at high risk for
VTE, speci cally lters that can be retrieved or repositioned
safely, without being compromised by entrapped clot or
contact point endothelialization for longer periods of time
relative to the risk of VTE. Until then, it is hoped that this
critical appraisal of the prophylactic use of VCFs, and the
current temporary lters that increasingly are linked to it,
will help guide physicians engaged in this practice.
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386 • VENOUS THROMBOEMBOLISM
46.
https://t.me/med1917
THROMBOLYTIC THERAPY FOR ACUTE VENOUS
THROMBOSIS
Anthony J. Comerota and Santiago Chahwan
INTRODUCTION
Despite evidence demonstrating that patients with iliofemoral venous thrombosis su er more severe postthrombotic sequelae than patients with infrainguinal deep venous
thrombosis (DVT), the majority of physicians treat all
patients with acute DVT with anticoagulation alone.
A treatment approach that includes a strategy of thrombus removal and optimal anticoagulation is not adopted
by most clinicians, even in patients with extensive venous
thrombosis.
Unquestionably, there have been enormous advances
in anticoagulation. Anticoagulants, such as low molecular weight heparins (LMWHs) and pentasaccharides, and
other families of agents, such as the direct thrombin inhibitors, serve to limit progression of thrombosis and, with
proper duration of therapy, prevent recurrences; however,
they are not designed to clear thrombus from the deep
venous system.
It appears that patients with iliofemoral DVT are a
clinically relevant subset of patients with acute DVT who
su er severe postthrombotic morbidity.
colleagues
the high incidence of postthrombotic venous ulceration,
the large number of recurrent hospitalizations, and the loss
in nancial productivity in these patients. Akesson etal.
showed that 95% of patients with iliofemoral DVT treated
with anticoagulation alone had ambulatory venous hypertension at 5years, and 90% su ered symptoms of chronic
venous insu ciency. During this relatively short follow-up,
15% of patients already developed venous ulceration, and
another 15% had debilitating symptoms of venous claudication. Delis etal.
occurred in 40% of patients with iliofemoral DVT treated
with anticoagulation when they were studied with exercise
testing.
1
were among the rst to bring to our attention
3
demonstrated that venous claudication
1–3
O’Donnell and
2
UNDERSTANDING
POSTTHROMBOTIC VENOUS
INSUFFICIENCY
Many physicians fail to recognize the di erence in the
pathophysiology of primary versus postthrombotic venous
insu ciency. As a result, the value of thrombus removal
in preventing postthrombotic morbidity in patients with
acute DVT is underestimated. e pathophysiology of
chronic venous insu ciency is ambulatory venous hypertension, which is de ned as an elevated venous pressure
during exercise. In individuals with a normal deep venous
system, ambulatory venous pressures in the lower leg and
foot should drop to less than 50% of the standing venous
pressure. In patients with postthrombotic syndrome, the
ambulatory venous pressure drops very little, and in those
with persistent proximal venous occlusion, the ambulatory
pressures may actually rise above standing pressure. is
degree of ambulatory venous hypertension o en leads to
the debilitating symptoms of venous claudication.
e anatomic components contributing to ambulatory
venous hypertension are venous valvular incompetence and
luminal obstruction. It has been consistently shown that
the most severe postthrombotic sequelae and the highest ambulatory venous pressures occur in patients with
valvular incompetence accompanied by luminal venous
obstruction.
Venous obstruction is not synonymous with occlusion. Occlusion is complete obliteration, whereas obstruction (for the most part) is relative narrowing of the lumen.
Although relative degrees of obstruction are reliably quantitated on the arterial side of the circulation, technology has
not advanced to the point that allows this degree of accuracy
on the venous side. Furthermore, physicians o en cannot
put venous obstruction into proper perspective pathophysiologically in terms of its contribution to postthrombotic
4,5
387
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