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134 Chapter 14 Direct contrast venography
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(a) (b)
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(b)
14.2 Before (a) and after (b) release of the tourniquet (arrow)
at the knee. Note the normal-looking duplicated popliteal
vein. Also note the supercial vein lling after the release
(arrowhead). Contrast will now ll the thigh veins, and by
squeezing the calf contrast bolus can be pressed up into the
thigh veins.
14.1 (a) Tourniquet is applied at the ankle for the rst part of
the study (arrow) to direct the contrast mixed blood into the
deep veins. Note that the anterior tibial vein is hardly lled.
(b) The tourniquet has now been released. Supercial veins
now do ll (arrow), and the anterior tibial vein pair is also lled
(arrowheads).
larger bolus of contrast-enhanced blood will enter the thigh
veins and ow toward the pelvic veins (Figure14.2). Up to
this time, the table has been kept tilted with the head end at
40–60 degrees. When the thigh veins have been evaluated,
the head end of the table can be lowered to horizontal level
or even to a head-down (Trendelenburg) position, and the
contrast-enhanced blood can be observed owing into the
pelvic veins and up to the inferior vena cava.
During the venogram, the examiner can turn the leg
inward and outward and take X-rays in different obliquities
to better understand the anatomy and any possible pathology.
By pressing on the sole of the foot, contrast lling the
plantar venous plexus (Figure14.3) can be ejected up into
the calf, which will increase the visualization of the calf
veins. Asimilar technique can be applied to the higher leg
segment, when manual compression of the calf forces contrast mixed blood into the thigh veins,
cation of these veins.
The contrast of choice is nonionic contrast medium,
typically with 300 mg/mL of iodine. For good lling of the
venous system, 100–150 mL of contrast should be injected
rmly. It is best to have an assistant injecting the contrast
increasing the opaci-
14.3 The plantar veins are nicely lled (arrow). By compressing
the sole, a bolus of contrast can be “squeezed” into the calf
veins, increasing their visibility.
14.2 Lower extremity ascending venography 135
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They also add that:
14.4 (a) Lateral view from a right lower extremity venogram.
(b) Front view (PA). Comparing the two views claries the anat-
omy, which is normal, but the anterior tibial vein is not lled
well, probably due to the tourniquet compressing the vein at
the ankle.
while the person performing the study rotates the leg medially and laterally under uoroscopic visualization and
takes images (X-rays) intermittently for review and documentation (Figure14.4). Different positions of the limb
help with three-dimensional understanding and clarify the
anatomy and possible pathology.
14.2.2 Indications
A diagnosis of DVT was the main indication for ascending venography until ultrasound took its place in the
early 1990s. Ascending venography still has its place for
the diagnosis of DVT in a select group of patients where
ultrasound has either been negative or inconclusive but
with high suspicion of DVT, as well as in instances where
ultrasound cannot be relied upon or cannot be performed
for some reasons (e.g., presence of a cast, severe swelling,
scar tissue). The American College of Chest Physicians
recommendations for the diagnosis of DVT stated that:
In patients with suspected rst lower extremity DVT
in whom [ultrasound] is impractical (e.g. when leg
casting or excessive subcutaneous tissue or uid prevent adequate assessment of compressibility) or nondiagnostic, we suggest [computed tomography] scan
venography or magnetic resonance (MR) venography, or MRdirect thrombus imaging could be used
as an alternative to venography.
In circumstances when high-quality venography
14
is available, patients who are not averse to the discomfort of venography, are less concerned about
the complications of venography, and place a high
value on avoiding treatment of false-positive results
are likely to choose conrmatory venography if ndings for DVT are less certain (e.g. a short segment of
venous no compressibility).
The new problem is related to the lack of experience
of some physicians/institutions. Indeed, the performance
of this study demands an understanding of the technical
aspects, as well as extensive training in the practice and
interpretation of the results and images.
In many cases, acute DVT causes occlusion of the vein,
which will then be seen on the venography as an abrupt
termination of the contrast-lled vein (Figure14.5a). Frequently, there is slight ow around the thrombus—between
the vein wall and the thrombus—giving an impression of
lines up along the vein, referred to as the “tram track sign”
(Figure 14.5b).
5,7,8
Abrupt occlusion and the tram track
sign are often regarded as the diagnostic signs of acute
DVT on ascending venography. The thrombus may not be
occlusive, but rather rmly adherent to the wall of the vessel on one side but allowing contrast to ow around the
thrombus (the lling defect sign) (Figure14.5c).
Chronic post-thrombotic changes are easily documented
on an ascending venogram. Use of an ankle tourniquet is
very important to direct the contrast into the deep vein system. If there are chronic thrombotic changes in the deep
veins, the pressure in the deep veins is typically high and
ow is diverted into the supercial system. The degree of
post-thrombotic changes varies from a patent vein with possible smaller-than-expected diameter and lack of valves (Figure14.6a) to complete occlusion with no lling of the vein
lumen. In-between ndings, corresponding to septations or
webs from the thrombus recanalization process, involve
small strands of contrast tracking along the previously
healthy veins, looking like a “water lter” (Figure14.6b).
Venography of patients with Klippel–Trenaunay syndrome
presents a logistical problem. The indication for a venogram
in this case is to demonstrate the patency and size of the deep
venous system, the extent of the supercial veins, and the communication from the supercial system to the deep system.
The deep system can often be small (hypoplastic); therefore,
it is important to have tight tourniquets around the ankle in
order to divert the contrast into the deep system (Figure14.7).
In difcult cases, Alomari
9
recommended identifying the perforating veins initially using ultrasound. Tourniquets could
then be placed at the level of the identied perforators, trying
to prevent early lling of the perforators,
9
so that the deep system can be better evaluated. In other instances, it may be the
marginal (lateral veins) and other congenital portions of the
system that are of interest for preoperative evaluation. In such
cases, large volumes of contrast may be needed to ll the veins
adequately
9
; therefore, Alomari9 recommended using diluted
contrast and subtraction imaging.
Currently, perforators are localized and evaluated for
incompetence using ultrasound and Doppler, but the tech-
6
nique of identifying and marking perforators with ascending
venography can be helpful. When looking for an incompe-
136 Chapter 14 Direct contrast venography
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14.5 (a) Occlusion (arrowhead) of one of the two peroneal vein branches with a lling defect (arrow). (b) Tram tracks are faintly
seen as contrast is traveling between the thrombus and the vessel wall (arrows), and the density is most when seen “tangential.” (c)
Thrombus adherent to the vein on one side but allowing ow around it (arrows) on the opposite side. Sometimes it is only held in
place by the thrombus caudally, and then it is referred to as a free-oating thrombus or thrombus tail.
14.6 (a) Right lower leg ascending venogram. Note normal
valve sinuses in the anterior tibial vein (arrow) indicative of a
normal vein. The peroneal vein is smooth with “wave” outlines and no valves, indicative of chronic post-thrombotic
changes (arrowhead). Note varicosity of the small saphenous
vein with lling of the vasa vasorum (hollow arrowhead) possibly indicating recent supercial thrombophlebitis. (b) Typical
post-thrombotic changes with a “water lter” appearance from
the recanalization process with webs (arrow).
14.7 Klippel–Trenaunay syndrome, left side. (a) Prominent
greater saphenous vein appearing to communicate with the
deep vein (arrowhead).
of the common femoral vein (arrow), and the greater saphenous
vein drains prepubically into the contralateral greater saphenous vein (arrowhead).
(b) Small femoral vein (arrow). No lling
tent perforator, a tourniquet should be placed around the
ankle to force the contrast into the deep venous system and
prevent contrast ow directly into the supercial system. On
ascending venogram, an incompetent perforating vein can be
seen lling from the deep venous system toward the supercial system (Figure 14.8).
10
It helps to have a measuring
14.3 Lower extremity descending venography 137
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(ultrasound, for example) for the diagnosis of DVT. Hull
12
followed patients who had negative venography for
et al.
DVT and found that 2 out of 160 (1.3%) patients who
were not treated based on negative ascending venography
presented within 8 days with veriable DVT. This was felt
to be a strong indication that patients with symptoms that
are suggestive of DVT but with negative ascending venograms could safely forgo treatment.
12
Ascending venography requires expertise and training, and one study found
that 10%–15% of ascending venography examinations
were inadequate for diagnostic purposes due to insufcient
contrast.
13
14.3 LOWER EXTREMITY
DESCENDING VENOGRAPHY
Ultrasound with Doppler can give accurate indications
of the location of the venous valvular incompetence.
Before that, in the 1980s, descending venography was
popularized, mainly for evaluating valvular competence
in the central lower extremity veins as workup for valvular surgery.
tive evaluation of patients with lower extremity valvular
incompetence.
14
This technique is still utilized for preopera-
14
14.8 A perforating vein (arrow) from the posterior tibial vein
to supercial varicosities. Note tourniquet around the ankle
(arrowhead).
device (radiopaque ruler) next to the examined leg at the
same time, so that the perforators can be identied on the leg
using bone landmarks such as the malleoli.
11
How good is ascending venography at detecting acute
DVT? Ascending venography served as the reference
study (gold standard) when evaluating new technology
14.3.1 Technique
Descending venography requires placement of a catheter
at the common femoral vein level (junction of the external
iliac and common femoral vein) or at the popliteal vein
level in the case of competent common femoral and femoral valves but suspicion of popliteal and calf incompetence
(this may require popliteal vein puncture).
gained from any accessible vein where a catheter can be
advanced to the common femoral veins, such as the internal jugular veins, arm veins, contralateral common femoral vein, and even the ipsilateral common femoral vein.
The procedure is performed with the patient supine on a
tilt-table with the head end elevated to approximately 60
degrees. Afootrest is in place and a block placed under the
contralateral foot such that the studied leg is free and nonweight-bearing. Contrast is then injected at 7 mL/second,
with a total volume of 70 mL, and the patient is asked to
perform the Valsalva maneuver during the injection. Care
must be taken that the X-ray equipment is positioned such
that the contrast can be followed below the knee and up
to the inferior vena cava during and immediately following
the injection.
Using uoroscopy, the examiner observes contrast ow
down the leg and images are taken, typically consisting of
spot images, but the uoroscopic evaluation can also be
stored as a “video recording.”
17
The reux is then graded
based on how far down the leg along the axial deep veins
the contrast descends during the injection.
cates no contrast beyond the common femoral vein conuence; grade 1 indicates reux into the femoral vein down
to, but not beyond, the mid-thigh (Figure14.9); grade 2
indicates reux beyond the mid-thigh but not into the popliteal vein; grade 3 indicates incompetence of the popliteal
vein but not beyond that, not opacifying the deep veins of
15
Access can be
14,18
Grade 0 indi-
14,16
138 Chapter 14 Direct contrast venography
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14.9 Bilateral lower extremity descending venogram. Puncture was made into the right common femoral vein and a catheter then
advanced over the bifurcation into the left common femoral vein, and the left extremity was examined. The catheter was then pulled
back into the right external iliac vein just above the puncture and the right veins evaluated.
grade 1 reux into the profunda femoral and femoral veins (arrows) with reux into a large and incompetent greater saphenous
vein (arrowhead). (b) Left leg venogram shows grade 1 reux into the mid-thigh vessels. See competent valves (arrows). Also note
post-thrombotic changes in the greater saphenous vein, which is incompetent (arrowhead).
the calf; and nally, grade 4 reux includes the deep veins
of the calf down to the ankle level. This grading is for the
deep veins only, but by positioning the catheter close to the
ostium of the greater saphenous vein, reux in that vein
can also be evaluated in a similar manner. It is important to
note that the test will not give any indication of the competency of the valve beyond the most cephalic competent
valve unless a catheter is placed below that level, either
with direct puncture or by advancing a catheter distal to
that level.
14.3.2 Indications
This study is mostly used to map the level of valvular
incompetence prior to venous valve surgery.
Descending venography is invasive, and ultrasound
with Doppler has very much replaced it for patient workup.
One of the challenges of the interpretation of the examination is that contrast may “leak” through the valves. It is
often difcult to decide whether this is true reux or clinically unimportant “leaky valves.”
17
14.4 UPPER EXTREMITY
VENOGRAPHY
Venography of the upper extremity is, in many regards,
akin to what was described for the lower extremity.
Venography is rarely used for the diagnosis of DVT
of the upper extremity, but occasionally ultrasound is not
convincing or uncertain, and in those cases, venography
provides the answer.
14.4.1 Technique
The venogram is carried out in a similar way to a lower
extremity venogram. An 18- to 20-gauge Angiocath is
placed into a dorsal hand vein and 20–30 mL of nonionic
contrast with 300 mg/mL of iodine is injected. Atourniquet can be placed at the elbow level or just above to force
the contrast into the deep vein system. The same criteria are
used to diagnose thrombus as for lower extremity DVT.
Sometimes, the venogram is performed with injection into
a dorsal hand vein. This is done for the purposes of delineating the venous anatomy, such as before the creation of a
dialysis stula. In such a case, it is best to place the access
needle peripherally to achieve dispersal of the contrast into
the supercial veins as well as the deep veins.
Venous thoracic outlet syndrome is caused by compression of the subclavian vein as it passes out of the chest in
front of the anterior scalene muscle, behind the costoclavicular muscle, and between the collarbone and the rst
rib. Venography was the most-used test for its diagnosis,
but now computed tomography and MRI have replaced
venography for the most part,
demonstrates whether there is occlusion or not, without
identifying the structures around the vein.
(a) Right leg venogram demonstrates
19,20
as venography only
8
References 139
(a) (b) (c)
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Left
Left
Left
14.10 Left upper extremity venogram with maneuvers directed at the diagnosis of thoracic outlet syndrome. (a) Neutral position. The
subclavian vein is narrow (arrow) at the medial vein and there are collaterals bridging (arrowhead).
the central subclavian vein is obstructed (arrow) and the collaterals are still seen (arrowhead).
head, the subclavian vein is narrowed (arrow) but the collaterals do not ll (arrowhead), probably because they are compressed.
Venography for thoracic outlet syndrome is typically
done with the patient lying at and supine on the exam-
collaterals with an obstruction, typically at the inner border of the rst rib (Figure14.10).
(b) With the arm at 90 degrees,
(c) With the arm stretched above the
ination table. An 18- to 20-gauge Angiocath is placed in an
antecubital vein and 20 mL of nonionic contrast with 300
mg/mL of iodine are injected rmly. Three separate studies
are typically done: the rst one has the arm lying neutral
by the patient’s side; the second has the arm reaching out
at 90 degrees holding a weight, such as a 1-L saline bag,
and the same injection is repeated; and the nal injection
is then performed with the arm stretched above the head.
On the second injection, impression at the pectoralis minor
muscle is often visible, and on the third injection, one can
usually see an impression at the thoracic outlet in the case
of compression. The diagnosis is made by imaging of the
14.4.2 Indication
Direct venography is a dying imaging technique, giving way
to more advanced cross-sectional imaging, such as MRI,
computed tomography, and, not least, ultrasound. The ability to visualize surrounding structures and obtain three-dimensional correlations makes these studies very valuable.
The addition of ow evaluation by ultrasound is signicant. However, direct contrast venography still has a
place in the evaluation of the patient with complex venous
abnormalities.
14
Consensus Statements 14.0 of the American Venous Forum on direct contrast venography
No. Consensus Statements
14.1 Contrast venography is helpful before performing endovenous reconstructions for acute or chronic venous disease.
14.2 Contrast venography may be helpful for patients suspected of having acute deep vein thrombosis only if other imaging
modalities are inconclusive.
REFERENCES
• Key primary papers
★ Major review articles
♦ Guidelines
1. Rabinov K., and Paulin S. Roentgen
diagnosis of venous thrombosis in the leg.
Arch Surg 1972;104(2):134–144.
2. Cronan J.J. Venous thromboembolic disease: The role of US. Radiology
1993;186(3):619–630.
3. Haeger K., and Sjukhuset A. Problems
of acute deep venous thrombosis: I. The
interpretation of signs and symptoms.
Angiology 1969;20(4):219–223.
4. Dos Santos J. La phlebographie directe.
Conception, technique, premiers resultats.
J Int Chir 1938;3:625–669.
5. Nicolaides A.N., Kakkar V.V., Field E.S.,
and Renney J.T. The origin of deep vein
thrombosis: Avenographic study. Br J
Radiol 1971;44(525):653–663.
♦
6. Bates S.M., Jaeschke R., Stevens S.M.,
etal. American college of chest physicians.
Diagnosis of DVT: Antithrombotic therapy
and prevention of thrombosis, 9th ed:
American College of Chest Physicians
evidence-based clinical practice guidelines.
Chest 2012;141(2 Suppl.):e351S–e418S.
•7. Andrews R.T. Contrast peripheral phlebography and pulmonary angiography for
diagnosis of thromboembolism. Circula-
tion 2004;109(12 Suppl. 1):I-22–I-27.
•8. Deweese J.A., and Rogoff S.M. Phlebographic patterns of acute deep venous thrombosis of the leg. Surgery1963;53:99–108.
•9. Alomari A.I. Diversion venography—A
modied technique in Klippel–Trenaunay
syndrome: Initial experience. J Vasc Interv
Radiol 2010;21(5):685–689.
10. Hach W. Varicose veins of the deep perforating veins—A typical phlebologic disease
picture. Vasa 1985;14(2):155–157.
11. Massell T.B., and Ettinger J. Phlebography
in the localization of incompetent communicating veins in patients with varicose
veins. Ann Surg 1948;127(6):1217–1225.
12. Hull R., Hirsh J., Sackett D.L., etal.
Clinical validity of a negative venogram in
patients with clinically suspected venous
thrombosis. Circulation 1981;64(3):
622–625.
13. Leizorovicz A., Kassai B., Becker F., and
Cucherat M. The assessment of deep vein
thromboses for therapeutic trials. Angio-
logy 2003;54(1):19–24.
•14. Kistner R.L., Ferris E.B., Randhawa G.,
and Kamida C. Amethod of performing
descending venography. J Vasc Surg
1986;4(5):464–468.
140 Chapter 14 Direct contrast venography
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15. Perrin M., Bolot J.E., Genevois A., and
Hiltband B. Dynamic popliteal phlebography. Phlebology 1988;3(4):227–235.
★16. Kistner R.L., and Kamida C.B. Update on
phlebography and varicography. Dermatol
Surg 1994;21(1):71–76.
17. Rosales A. Valve reconstructions. Phlebo-
logy 2015;30(1 Suppl.):50–58.
18. Herman R.J., Neiman H.L., Yao J.S.,
Egan T.J., Bergan J.J., and Malave S.R.
Descending venography: Amethod of
evaluating lower extremity venous
valvular function. Radiology
1980;137(1):63–69.
19. Demondion X., Herbinet P., Van Sint Jan
S., Boutry N., Chantelot C., and Cotten
A. Imaging assessment of thoracic outlet
syndrome. Radiographics 2006;26(6):
1735–1750.
♦20. Moriarty J.M., Bandyk D.F., Broderick
D.F., etal. ACR appropriateness criteria imaging in the diagnosis of thoracic
outlet syndrome. J Am Coll Radiol
2015;12(5):438–443.
CHAPTER
15
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Intravascular ultrasound
Paul J. Gagne
15.1 INTRODUCTION
The use of intravascular ultrasound (IVUS) has fundamentally changed the treatment for many patients suffering
from severely symptomatic chronic venous hypertension
(CVH), especially those with clinical CEAP 4, 5, and 6 diseases. Not so long ago, many vascular specialists believed
that valve dysfunction was the primary pathophysiology
of CVH and its associated lower extremity skin damage
and pain. The role of deep vein obstructive disease as an
important component of CVH is now much better appreciated. It is now well-recognized, in large part due to IVUS
imaging, that many patients suffer from CVH due to either
post-thrombotic iliofemoral vein occlusive scarring and
severe compression of the common and external iliac vein
or common femoral vein, or both. Aclassic May–Thurner
compression lesion where the left common iliac vein is
compressed by the right common iliac artery is no longer the only nonthrombotic iliac vein compression lesion
(NIVL) that is recognized, and it is now known to occur in
both the right and left leg (1). It is also clear that stenting of
the central pelvic vein (i.e., iliac or common femoral vein)
outow tract obstruction is oftentimes effective as a sole
intervention for improving severely symptomatic advanced
CVH (1, 2).
15.2 BACKGROUND
Once thought to be a technology looking for an application, IVUS is now widely accepted as necessary imaging for the diagnosis and treatment of deep vein disease.
IVUS has vastly expanded the ability to identify intraluminal and intramural venous pathology and extrinsic vein
compression compromising lumen adequacy. This was
rst identied by Drs. Neglen and Raju (3). Their seminal paper in 2002 identied the ability of IVUS to identify
iliac vein stenosis better than venogram. Their subsequent
papers in 2006 (1) and 2007 (2) highlighted the frequency
of IVUS-identied signicant post-thrombotic and NIVL
lesions in patients with clinical CEAP 3–6 disease. These
two reports highlighted that IVUS-guided treatment of iliac
and common femoral vein stenosis with stents led to high
patency, low thrombotic complications, and signicant
clinical improvement of advanced CVH symptoms. They
also provided a word of caution about treating clinical
CEAP 3 patients. Only half their patients improved after
stent placement. Patients with leg edema alone often have
multiple factors resulting in edema. Treating these patients
with stents will lead to disappointment in the outcome for
both patient and physician. These patients should undergo
stent placement only rarely and after all other etiologies of
edema have been thoroughly assessed and treated.
The added value of IVUS compared to multiplanar
venography alone was conrmed in the VIDIO study (4)
examining clinical CEAP 4–6 patients. VIDIO showed that
the addition of IVUS detected iliac and common femoral
vein occlusive lesions more frequently than multiplanar
venography alone. This increased detection led to increased
stenting of deep vein lesions and clinical improvement at
6 months (4). The prospective, single-arm IDE trial evaluating the safety and efcacy of the ABRE venous stent
in clinical CEAP 3–6 patients used IVUS as the primary
imaging technology for identifying signicant iliofemoral
vein disease and to guide stent placement (5). The 1- and
3-year data from the ABRE trial revealed a clinically significant improvement following IVUS-guided evaluation and
stenting of iliofemoral vein obstruction in these patients’
CVH symptoms compared to baseline (5, 6).
The increased sensitivity of IVUS for identifying
iliofemoral venous occlusive disease in patients with severe
CVH has made stenting of deep veins more common. IVUS
is critical for the accurate measurement of the intraluminal diameter of veins and proper sizing of therapeutic
iliac and common femoral vein stents. Aconsequence of
inaccurate stent size determination is now well-recognized
as the signicant complication of stent embolization (7).
Furthermore, stent patency, a critical metric in the therapeutic management of iliac and common femoral vein outow tract obstruction, is believed to be, in part, dependent
upon the absence of stenotic disease affecting inow or
outow to and from the stent and adequate stent expansion and lumen gain. IVUS, given its increased sensitivity
for identifying lesions not evident on venogram or axial
imaging, has proven helpful for allowing interventionalists to avoid undertreatment of venous occlusive disease,
especially in post-thrombotic patients with diffuse scarring
(Figure15.1).
DOI: 10.1201/9781003328971-17
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142 Chapter 15 Intravascular ultrasound
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15.1 Venogram and IVUS of the common femoral vein (CFV) and the deep femoral vein (DFV) (arrow). Note the supercial femoral
artery (SFA) and the profunda femoris artery just lateral and under the CFV on IVUS.
The prospective randomized study performed by Rossi
et al. (8) showed that IVUS-guided stenting of iliac and
common femoral vein outow tract obstruction plus compression therapy improved venous ulcer healing and resolution of lower extremity symptoms of venous hypertension
better than compression therapy alone. This small prospective, randomized trial afrms the observations from cohort
studies that IVUS-guided treatment of deep venous occlusive disease is a critical component in the overall therapy
for severe CVH patients.
15.3 IVUS-IDENTIFIED LESIONS
AND HOW TO INTERPRET THE
DEGREE OF STENOSIS
IVUS-identied occlusive disease can be a focal lesion due
to compression or NIVL or diffuse disease over multiple
segments due to a post-thrombotic scar (PTS). Determining
whether the lesions identied are clinically signicant or
not in clinical CEAP 4–6 patients is different for NIVL versus PTS. A50% diameter stenosis on a venogram has traditionally been considered hemodynamically signicant and
the threshold for stent placement. Neglen and Raju (1, 2)
identied a 50% cross-sectional area reduction by IVUS as
clinically signicant and should be stented in appropriate
CVH patients. Apost hoc analysis of the VIDIO data (9)
identied a 54% cross-sectional area reduction by IVUS as
a better predictor of clinical improvement at 6 months following stent placement. VIDIO also determined in a post
hoc analysis of the data that for patients with symptomatic
(i.e., clinical CEAP 4–6) NIVL lesions, a 61% IVUS-determined diameter stenosis was a better threshold lesion for
stenting and achieving clinical improvement at 6 months
than a 54% area reduction. This was a retrospective
analysis of a small number of patients, however. To date,
no prospective comparison of these criteria for intervention has been assessed. The body of literature, however,
supports a greater than 50% cross-sectional area reduction
in clinical CEAP 4–6 patients as generally resulting in measurable clinical improvement following stent placement.
Though it is often clear where a cross-sectional area reduction in a vein is with IVUS using visual inspection and measuring with the supplied software, it is sometimes uncertain
where the reference vessel for comparison is to calculate
the degree of lumen compromise. It is not uncommon for
a severely compressed common iliac vein to be adjacent to
a signicantly larger normal vein, possibly dilated inferiorly, over a very short CIV segment (Figure15.2). In this
instance, the “reference” vessel for comparison to the stenosed area may be a contralateral common iliac vein,
an “idealized,” 16-mm common iliac vein. ANIVL lesion
of the common or external iliac vein can be detected with
IVUS and the narrowed lumen measured with the available
software, but the size of the reference vessel adjacent to the
area of compression can be affected by phasic changes with
respiration. This is likely in part related to the hydration
status and horizontal position of the patient. It is critical
in patients with NIVL lesions to perform “dynamic” IVUS
imaging of the lesion and the reference vessel for proper
calculation of the true diameter and area (Figure15.3). The
IVUS catheter is positioned at one spot in the EIV and the
patient is instructed to take deep breaths. Changes in EIV
size are often seen. The severity of the suspected stenosis
and the size of the vessel for proper stent selection can be
determined in this way and is essential to prevent inappropriate stenting or stent embolization.
Recent work done by Chouinard and colleagues (10)
has shown that the technique for calculating the vein lumen
cross-sectional area at a compression stenosis with IVUS
can affect diameter calculations. Mathematically calculating the diameter from the measured vein lumen area or
or
15.3 IVUS-identified lesions and how to interpret the degree of stenosis 143
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15.2 Venogram and IVUS show stenosis (A) of the common iliac vein (CIV) (arrow). The CIV was dilated and stented (B), IVUS
conrmed stenosis (C).
15
Reference
15.3 Phasic external iliac vein size change with respiration.
directly measuring the minimum and maximum diameter
and averaging the two have long been common techniques
for calculating the diameter. Measurement of the periphery
or circumference of the vein, however, can lead to a different diameter measurement, especially with a more irregular
vein lumen shape (Figure 15.4). More work needs to be
done to better understand this variability, but the presence
of these data suggests that oversizing a stent compared
Stenosis
to the measured vein lumen by only a millimeter may be
inadequate and permit stent embolization. Oversizing the
stent more rather than less within the instructions for use
or IFU for commercially available stents is likely a better,
and safer, strategy.
Patients with diffuse post-thrombotic stenosis or occlu-
sion often do not require IVUS to identify the presence
of a hemodynamically signicant stenosis. This is often
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