Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3657_Библиотеки_им_академика_М_И_Перельмана.pdf
11 IVC Filters
These results support the current ACCP and SIR guidelines, which do not recommend placement of IVC lters
in patients who can receive AC therapy [3, 14]. In patients
who have a contraindication to AC, however, there is evidence of benets for IVC lter placement. A retrospective
study of patients with acute VTE and active bleeding
demonstrated 30-day mortality risk reduction of 32% and
90-day mortality risk reduction of 27% in patients who
received IVC lters compared to patients who did not
[21]. Like the PREPIC trials, this retrospective study
demonstrated increased DVT risk in all patients who
received IVC lters [21]. The etiology of DVT in the setting of IVC lters may be due to a combination of lterinduced ow changes and the underlying prothrombotic
systemic condition in the patient. An understanding of the
evidence for PE prevention and increased DVT risk is
essential for counseling patients and referring clinicians
on the appropriate application of IVC lters.
Key Point
IVC lters increase the risk for DVT formation/propagation and therefore should be removed once no longer
indicated.
145
The How To: IVC Filter Placement
Preprocedural Preparation
Prior to IVC lter placement, any available cross-sectional
abdominal imaging should be evaluated for the presence and
extent of DVT as well as the presence of aberrant IVC anatomy (Key Point). The availability of venous access sites,
typically IJ or common femoral veins, should be assessed,
particularly in patients with extensive clot burden or limited
venous reserve. The patient’s coagulation status should be
assessed for any major coagulopathy. Anticoagulation status
and platelet level should be assessed to ensure that the patient
can safely pursue IVC lter placement.
Key Point
Aberrant IVC anatomy
• Circumaortic left renal vein (7%)– lower component is retroaortic and drains into the IVC below the
preaortic renal vein.
• Duplicated IVC (1%)– joins at left renal vein.
• Left-sided IVC (<1%) retroaortic left renal
vein(3%) drains into IVC below the right renal vein.
• Megacava– IVC diameter>28mm (1%).
Key Point
IVC lters should be deployed inferior to the lowest
renal vein.
146
J. Chen and S. W. Stavropoulos
Fig. 11.3 A 45-year-old man with intracranial hemorrhage following
head trauma from a motor vehicle collision developed acute iliofemoral
DVT during his hospitalization. Anticoagulation was contraindicated
due to the presence of acute intracranial hemorrhage (a) A marker pigtail catheter was introduced from the right common femoral vein and
positioned at the conuence of the iliac veins (arrow), and subtraction
Complication
Access Site
• Hematoma
• Venous thrombosis
• Arteriovenous stula
Access site complications are rare with most modern lowprole lter delivery systems and ultrasound-guided percutaneous techniques.
Device-Related
• Immediate
– Failed lter deployment
– Filter malposition
• Delayed
– Filter migration
– Filter fracture and embolization
– Filter penetration of the IVC and penetration of adja-
cent organs
– Caval thrombosis and deep venous thrombosis
Although IVC lter complications usually have a benign
clinical course, there have been reports of severe clinical
cavography was performed. The areas of absent contrast opacication
(arrowheads) correspond to the inow of unopacied blood from the
renal veins. A radiopaque ruler was positioned in the eld of view to
provide a reference point for the level of the renal veins. (b) Spot image
demonstrated successful deployment of an optional IVC lter in the
infrarenal IVC
sequelae, particularly in cases where the lter or a fractured
lter component embolizes to critical structures like the
heart or pulmonary artery, potentially causing arrhythmias,
myocardial perforation with resultant tamponade, or pulmonary embolism. In a systemic review of complications among
optional IVC lters, the mean incidence of migration was
1.3%, and IVC thrombosis or stenosis was 2.8% [16]. The
risk of lter fracture is estimated at around 1% [16]; however, the true incidence of lter fracture is not denitively
known, as many descriptions are in the form of case reports
or submissions to the Manufacturer and User Facility Device
Experience (MAUDE) database [22]. Furthermore, these
risks may vary between models. Denitive comparison of
the safety prole between IVC lter models has been limited
to date, but the pending PRESERVE (Predicting the Safety
and Effectiveness of Inferior Vena Cava Filters) prospective
multicenter trial may offer more insight into which, if any, of
the lters have lower complication rates.
Postprocedural Management
Immediately following lter placement, patients are kept on
bedrest (approximately 2–4h, although regimens vary between
institutions and providers) to reduce the risk of access site
complications. For long-term follow-up, patients with both
11 IVC Filters
147
permanent and optional IVC lters should be evaluated for the
possibility of initiating systemic AC once/if contraindications
no longer exist. For optional lters, routine follow-up should
be performed to ensure removal of the lter once it is no longer needed. Recognition of device-related complications
prompted the FDA to issue communications in 2010 and 2014
[23, 24], which emphasized the need for prompt IVC lter
removal once the period requiring mechanical protection
against PE had elapsed. The physician who placed the lter
should be responsible for follow-up and retrieving the lter as
soon as it is appropriate, but rigorous adherence can be challenging, and lter retrieval rates remain lower than desired
[25], ranging between approximately 12% and 45% [16]. To
address this challenge, institutions have developed dedicated
IVC lter clinics [26] and multidisciplinary quality improvement programs [27] to facilitate mechanisms of communication between providers and patients. Through these initiatives,
lter retrieval rates were improved from 29–60% [26] and
23–45% [27] at the respective institutions.
IVC Filter Retrieval
IVC lter retrieval should be considered in patients with
optional lters when the period of VTE risk has elapsed or
systemic AC has been achieved. Device-related complications like lter fracture, which are often incidentally detected,
should also motivate prompt lter removal, to reduce the risk
of progression to clinically signicant adverse events.
The How To: Standard IVC Filter Retrieval
Key Point
IVC lters removal should be considered as soon as
the risk of VTE is acceptably low and/or if lter-related
device complications are detected.
The success of standard retrieval techniques is dependent
on a favorable lter tip position; consequently the most common reasons for unsuccessful retrieval are lter tilt and tip
embedment in the wall of the IVC.Additional features that
may preclude successful standard retrieval approach include
lters with prolonged dwell times resulting in extensive
component endothelialization or lters complicated by fracture [16, 28]. Pre-retrieval CT, MRI, or rotational angiography is recommended to assist procedural planning, assess the
potential risks of endovascular lter removal, and identify
cases of lter penetration with invasion into adjacent organs.
Magnication spot radiographs at the time of the procedure
are also valuable to evaluate for lter fracture. These preremoval imaging techniques will help to decisively recognize the presence of any of these features which may preclude
successful retrieval with standard techniques and therefore
require advanced lter retrieval techniques.
Key Point
Spot magnication images should be obtained prior to
venous access to determine the structural integrity of
the lter.
Advanced IVC Filter Retrieval Techniques
In brief, a variety of advanced retrieval tools and methods
have been developed to address complicated IVC lter
retrieval circumstances [29]. For tip-embedded IVC lters,
endobronchial forceps can be used to remove the lters. The
forceps are introduced using a sheath via the right internal
jugular vein and used to microdissect the tip of the IVC lter
from the IVC wall. Once free, the lter is then engaged with
the jaws of the forceps (Fig.11.5), and retrieval is performed
by combined forceps traction and oversheathing. This modality has achieved an excellent success rate for retrieval of tipembedded lters and can be performed with a low rate of
148
J. Chen and S. W. Stavropoulos
Fig. 11.4 A 53-year-old woman with gastrointestinal hemorrhage
in the setting of anticoagulation for pulmonary embolism presented
for retrieval of previously placed IVC lter. (a) Initial spot magnied uoroscopic images conrmed an intact lter. (b) A pigtail
catheter was advanced to the conuence of the common iliac veins
via right IJ access, and subtraction cavography was performed, con-
major complications [30]. Other techniques include the loop
snare technique in which a wire is snared through the lter
struts and back out through the jugular sheath. Laser-assisted
sheath tissue ablation can be used to remove lters where
there is signicant scar tissue around the lter struts precluding removal using safe amounts of tension. A laser sheath is
introduced via the right internal jugular vein and extended to
the point of resistance, where the laser is activated to ablate
the tissue around the lter struts. This modality has been
shown to signicantly reduce the amount of retraction force
required to remove the lter [31].
rming well- centered position, with minimal caval narrowing. (c) A
snare was used to engage the apical hook on the lter (arrowhead).
(d) The snare was tightened on the apical hook and used to provide
traction as the lter was oversheathed, which collapsed the lter
limbs, separating the lter from the IVC wall and allowing for lter
removal via the sheath
Conclusion
IVC lters provide effective mechanical protection against
PE in patients with DVT and are available in a range of permanent and optional models. Indwelling lters are associated with an increased risk of DVT as well as device-related
complications such as lter migration and component fracture. IVC lters should therefore be used judiciously, for
patients in whom systemic AC is contraindicated or ineffective, and require close clinical follow-up to allow for prompt
lter retrieval once the period of VTE risk has elapsed.
11 IVC Filters
Fig. 11.5 Fluoroscopic image during retrieval of a tip embedded IVC
lter demonstrated successful engagement of the apex of the lter by
the jaws of the endobronchial forceps (arrowhead). The vascular sheath
has been partially advanced over the tip of the IVC lter
References
1. Heit JA. Epidemiology of venous thromboembolism. Nat Rev
Cardiol. 2015;12:464–74.
2. Beckman MG, Hooper WC, Critchley SE, Ortel TL. Venous
thromboembolism: a public health concern. Am J Prev Med.
2010;38:S495–501.
3. Kearon C, Akl EA, Ornelas J, Blaivas A, Jimenez D, Bounameaux
H, etal. Antithrombotic therapy for VTE disease: CHEST guideline
and expert panel report. Chest. 2016;149:315–52.
4. Mobin-Uddin K, Callard GM, Bolooki H, Rubinson R, Michie
D, Jude JR. Transvenous caval interruption with umbrella lter.
NEngl JMed. 1972;286:55–8.
5. Wingerd M, Bernhard VM, Maddison F, Towne JB.Comparison of
caval lters in the management of venous thromboembolism. Arch
Surg. 1978;113:1264–71.
6. Greeneld LJ, Zocco J, Wilk J, Schroeder TM, Elkins RC.Clinical
experience with the Kim-ray greeneld vena caval lter. Ann Surg.
1977;185:692–8.
7. Johnson MS, Nemcek AA Jr, Benenati JF, Baumann DS, Dolmatch
BL, Kaufman JA, etal. The safety and effectiveness of the retrievable option inferior vena cava lter: a United States prospective
multicenter clinical study. JVasc Interv Radiol. 2010;21:1173–84.
8. Le Blanche AF, Ricco JB, Bonneau M, Reynaud P.The optional
VenaTech() convertible () vena cava lter: experimental study in
sheep. Cardiovasc Intervent Radiol. 2012;35:1181–7.
9. Lyon SM, Riojas GE, Uberoi R, Patel J, Lipp ME, Plant GR, etal.
Short- and long-term retrievability of the Celect vena cava lter:
results from a multi-institutional registry. J Vasc Interv Radiol.
2009;20:1441–8.
149
10. Smouse HB, Rosenthal D, Thuong VH, Knox MF, Dixon RG,
Voorhees WD 3rd, et al. Long-term retrieval success rate prole for the Gunther Tulip vena cava lter. J Vasc Interv Radiol.
2009;20:871–7. quiz 8
11. Stavropoulos SW, Chen JX, Sing RF, Elmasri F, Silver MJ, Powell
A, et al. Analysis of the nal DENALI trial data: a prospective,
multicenter study of the Denali inferior vena cava lter. J Vasc
Interv Radiol. 2016;27:1531–8. e1
12. Ziegler JW, Dietrich GJ, Cohen SA, Sterling K, Duncan J,
Samotowka M.Proof trial: protection from pulmonary embolism
with the OptEase lter. JVasc Interv Radiol. 2008;19:1165–70.
13. Mismetti P, Rivron-Guillot K, Quenet S, Décousus H, Laporte S,
Epinat M, etal. A prospective long-term study of 220 patients with
a retrievable vena cava lter for secondary prevention of venous
thromboembolism. Chest. 2007;131:223–9.
14. Caplin DM, Nikolic B, Kalva SP, Ganguli S, Saad WE, Zuckerman
DA, Society of Interventional Radiology Standards of Practice
Committee. Quality improvement guidelines for the performance
of inferior vena cava lter placement for the prevention of pulmonary embolism. JVasc Interv Radiol. 2011;22:1499–506.
15. Stein PD, Matta F, Hull RD.Increasing use of vena cava lters for
prevention of pulmonary embolism. Am JMed. 2011;124:655–61.
16. Angel LF, Tapson V, Galgon RE, Restrepo MI, Kaufman
J. Systematic review of the use of retrievable inferior vena cava
lters. JVasc Interv Radiol. 2011;22:1522–30. e3
17. Vijay K, Hughes JA, Burdette AS, Scorza LB, Singh H, Waybill
PN, et al. Fractured bard recovery, G2, and G2 express inferior
vena cava lters: incidence, clinical consequences, and outcomes
of removal attempts. JVasc Interv Radiol. 2012;23:188–94.
18. Decousus H, Leizorovicz A, Parent F, etal. A clinical trial of vena
caval lters in the prevention of pulmonary embolism in patients
with proximal deep-vein thrombosis. Prevention du Risque
d'Embolie Pulmonaire par Interruption Cave Study Group. N Engl
JMed. 1998;338:409–15.
19. Group PS. Eight-year follow-up of patients with permanent vena
cava lters in the prevention of pulmonary embolism: the PREPIC
(prevention du Risque d'Embolie Pulmonaire par interruption cave)
randomized study. Circulation. 2005;112:416–22.
20. Mismetti P, Laporte S, Pellerin O, etal. Effect of a retrievable inferior vena cava lter plus anticoagulation vs anticoagulation alone
on risk of recurrent pulmonary embolism: a randomized clinical
trial. JAMA. 2015;313:1627–35.
21. White RH, Brunson A, Romano PS, Li Z, Wun T. Outcomes
after vena cava lter use in noncancer patients with acute venous
thromboembolism: a population-based study. Circulation.
2016;133:2018–29.
22. Andreoli JM, Lewandowski RJ, Vogelzang RL, Ryu
RK.Comparison of complication rates associated with permanent
and retrievable inferior vena cava lters: a review of the MAUDE
database. JVasc Interv Radiol. 2014;25:1181–5.
23. US Food and Drug Administration: Inferior vena cava (IVC) lters:
initial communication. Risk of adverse events with long term use.
2010.
24. US Food and Drug Administration: Removing retrievable inferior
vena cava lters: FDA safety Communication. 2014.
25. Sarosiek S, Crowther M, Sloan JM. Indications, complications,
and management of inferior vena cava lters: the experience in 952
patients at an academic hospital with a level I trauma center. JAMA
Intern Med. 2013;173:513–7.
26. Karp JK, Desai KR, Salem R, Ryu RK, Lewandowski
RJA.Dedicated inferior vena cava lter service line: How to optimize your practice. Semin Interv Radiol. 2016;33:105–8.
27. Winters JP, Morris CS, Holmes CE, etal. A multidisciplinary quality improvement program increases the inferior vena cava lter
retrieval rate. Vasc Med. 2016;22:51–6.
150
J. Chen and S. W. Stavropoulos
28. Ray CE Jr, Mitchell E, Zipser S, Kao EY, Brown CF, Moneta
GL.Outcomes with retrievable inferior vena cava lters: A multicenter study. JVasc Interv Radiol. 2006;17:1595–604.
29. Iliescu B, Haskal ZJ.Advanced techniques for removal of retrievable inferior vena cava lters. Cardiovasc Intervent Radiol.
2012;35:741–50.
30. Stavropoulos SW, Ge BH, Mondschein JI, Shlansky-Goldberg
RD, Sudheendra D, Trerotola SO. Retrieval of tip-embedded
inferior vena cava lters by using the endobronchial forceps technique: Experience at a single institution. Radiology.
2015;275:900–7.
31. Kuo WT, Odegaard JI, Rosenberg JK, Hofmann LV.Excimer laserassisted removal of embedded inferior vena cava lters: A singlecenter prospective study. Circulation Cardiovascular Interventions.
2013;6:560–6.
Dialysis Fistulae andGrafts
DheerajK.Rajan
Pathophysiology
End-stage renal disease (ESRD) affects 660,000 patients in
the United States and over two million people globally. Of the
ESRD patients in the United States, 468,000 are dialysis
patients. Furthermore, the dialysis population is growing
4–6% annually, with prevalence increasing at a higher rate
because people are living longer. An effective hemodialysis
treatment is dependent on a well-functioning vascular access
which has good blood ow, has long-term patency, and allows
two to ve times per week dialysis treatment over the patient’s
lifetime. There are three types of vascular access: arteriovenous stula, arteriovenous graft, and venous catheter. The
venous hemodialysis (HD) catheter is described in Chap. 9.
Arteriovenous Fistula
An autogenous arteriovenous stula (AVF) is preferred for
long-term access for dialysis due to its lowest rates of infection and thrombosis, best potential blood ow, and least
expense. In 1966, Brescia, Cimino, Appel, and Hurwich
described the surgical creation of the arteriovenous stula
which is a connection between a native artery and vein, typically in the arm [1, 2]. In 2003, the “Fistula First” initiative,
a continuous quality improvement project, aimed to increase
the use of stulae for hemodialysis access. In 2009, the goal
was set to 65% prevalence which was largely reached.
The most common types of stulae are the radiocephalic
stula in the forearm, the brachiocephalic stula in the upper
arm, and the transposed brachiobasilic stula where the
basilic vein may be surgically elevated to make it more
D. K. Rajan (*)
University Health Network, University of Toronto, Medical
Imaging, Toronto, ON, Canada
e-mail: dheeraj.rajan@uhn.ca
12
accessible. Less common types are the ulnar-basilic forearm
stula, the percutaneous ulnar-ulnar stula, and a variety of
obscure leg stulas [3].
After surgery, the outow vein needs to gradually enlarge
to allow repeated punctures, a process called maturation.
Maturation time can be long, subjecting patients to prolonged catheter dependency and their associated morbidity
and mortality due to higher rates of venous thrombosis and
bloodstream infections [4]. Up to 60% [5] of stulae may
fail to mature enough to support dialysis. The rule of 6’s
from Kidney Dialysis Outcomes Quality Initiative (KDOQI)
is the most commonly used consensus denition to describe
stula maturation although several other anecdotal denitions have been proposed. KDOQI is described in detail
later [6]. The stula vein should be 6mm in diameter and
less than 6mm below the skin and have at least 600ml/min
ow. This denition is a consensus denitionnot based on
any objective data. Another sonographic criteria of maturation is a vein diameter of ≥4mm, and brachial artery ow is
>500ml/min [7]. Ultimately, the real determinant of stula
maturation is whether it supports therapeutic two-needle
dialysis.
Key Point
KDOQI rule of 6’s
• Fistula vein >6mm
• <6mm below the skin
• At least 600mL/min ow rate
Aneurysmal stula veins are common, and unlike graft
pseudoaneurysms, these are not pathologic sites of contained
rupture. They are most frequently found in areas of needling
and are often the result of a downstream stenosis increasing
intra-stula pressure [8]. However, they can be potential areas
of life-threatening rupture if the overlying skin over them is
© Springer International Publishing AG, part of Springer Nature 2018
N. A. Keefe et al. (eds.), IR Playbook, https://doi.org/10.1007/978-3-319-71300-7_12
151
152
taut, is shiny, or has an overlying scab. In these cases, urgent
surgical consultation is recommended for possible revision.
Occasionally the entire stula becomes enlarged which is
also known as a “mega stula.” When such a stula becomes
clotted, it can contain >20ml of clot. Such stulas are very
difcult to declot and carry a high risk of clinically signicant
periprocedural pulmonary emboli. Surgical thrombectomy
can be considered. There has been limited success with overnight catheter-directed thrombolytic therapy for such cases.
Arteriovenous Graft
The arteriovenous graft consists of a piece of prosthetic tubing
interposed between an artery and a vein where the tube itself
is punctured during dialysis. Dialysis grafts are composed of a
variety of different materials: the most common is polytetrauorethylene with a diameter of 6mm or tapering from 4 to
7mm. Since a prosthetic material is used to bridge the artery
and vein, infection is more common than with a native stula.
Dialysis grafts can be placed within the leg, chest, and most
commonly within the arms in a straight or looped conguration. Within the leg, the graft spans the femoral artery and the
femoral or saphenous veins. The rare necklace graft is created
between the subclavian artery on one side and the subclavian
vein on the other side of the chest.
Forearm grafts are most commonly looped between the
brachial artery and cephalic/basilic vein with the anastomoses near the elbow. A straight conguration can also be
placed between the radial artery in the distal forearm and the
cephalic/antecubital or basilic vein near the elbow. Within
the upper arm, the most common conguration is the straight
graft between the brachial artery and basilic or axillary vein.
Physical Examination ofthePatient
The physical exam has been proven to be as accurate at
diagnosing the cause of access dysfunction as the measures
of adequacy obtained during dialysis such as recirculation,
kt/v, and ow rates. Examining the arms can help determine areas of prior and current access. Furthermore, it can
demonstrate if central venous stenosis or occlusions exist–
if the arm with the dialysis access is swollen relative to the
non-access arm, a central venous lesion is likely (Fig.12.1).
It is very important to differentiate a dialysis stula from a
dialysis graft as location of stenosis, direction of access for
intervention, and outcomes are different. Dialysis grafts are
palpable as rigid tubular structures then compress but with
some difculty. Noting their location and conguration
helps with planning intervention. Dialysis (autogenous) stulas are also tubular but more compressible and “rubbery”
to the touch; this represents dilated veins that have been
D. K. Rajan
Fig. 12.1 Patient with a right arm brachiocephalic stula. Note the
swollen right hand and distal forearm relative to the left suggesting central venous stenosis or obstruction on the right
arterialized by surgically anastomosing them to arteries
within the arm.
Most importantly, note the presence or absence of a palpable thrill or audible bruit. A bruit sounds like a continuous
whooshing noise, and a thrill feels like a constant vibration
which corresponds to the blood passing through the stula.
These are in contrast to a prominent pulse which would suggest a patent access with a nearby downstream stenosis. If a
thrill or pulse is absent, the dialysis access is likely thrombosed or has a severe inow (arterial) or outow (venous)
stenosis. If a thrill is present, a change in the nature and
extent of the thrill throughout the access can localize an area
of stenosis. Thrombosis, stenosis, and infection are the three
most prevalent complications.
Steal syndrome is a clinical diagnosis representing insufcient arterial perfusion to the distal arm/hand. The dialysis
access “steals” too much blood from the brachial artery rendering the hand ischemic. Physical examination will reveal a
mottled hand, loss of pulses, poor nger oximetry waveforms, and potential sensory disturbance. Urgent surgical
consultation is recommended which may consist of banding
the stula to reduce its caliber, a DRIL procedure to reroute
ow, or in rare cases intentionally shutting down the access.
The later can be performed endovascularly.
Key Point
How to differentiate AVF from AVG
• AVF are easily compressible and rubbery to the touch.
• AVG have a rigid tube which is compressible but
with difculty.
12 Dialysis Fistulae andGrafts
153
Fig. 12.2 Thrombosed loop thigh graft. After insertion of the sheath,
pus was aspirated. Note the air within the graft consistent with gross
infection (black arrows)
Key Point
On physical exam, a bruit is heard, while a thrill is
palpated.
Other key ndings on examination include erythema,
warmth, and tenderness which may reect cellulitis and
infection (Fig. 12.2). Finally, for dialysis stulae, some
patients use an access technique called a “button hole”
wherein they insert their dialysis needles at the same locations every time. These hardened areas may provide easier
access but can become focal areas of eventual stenosis.
Dilated chest wall veins may suggest central venous stenosis
or occlusion (Fig.12.3). Multiple scars from previous dialysis catheters suggest a greater risk of central venous disease.
Both dialysis catheters and grafts are associated with higher
risk of infection and a greater number of interventions than
AV stula to maintain patency. Graft infection is relative
contraindication to angioplasty and an absolute contraindication to declotting. Septic embolization of infected thrombus
is the primary concern and carries a high risk of mortality.
When accessing the graft, aspiration with the puncture needle may return pus.
Over the past two decades, interventional radiologists
have increasingly become involved in the evaluation and
Fig. 12.3 Patient from Fig.12.1 with a right brachiocephalic stula. In
addition to a swollen arm, a dilated venous chest wall collateral is visible also strongly indicating central venous stenosis or obstruction
treatment of hemodialysis access. The concerted effort
between interventional radiologists, vascular surgeons, and
nephrologists has proven effective in prolonging vascular
access patency and decreasing morbidity and mortality of
ESRD patients.
Key Point
Easiest way to differentiate arterial from venous limb
of a graft? Ask the patient.
Key Point
Easiest way to determine the direction of ow within
the graft is to compress in the middle and feel which
side has a pulse.
Clinical Indication
The indication for intervention in an access is clinical dysfunction combined with angiographic and/or ultrasound evidence of a signicant vascular stenosis. Clinical indications
include but are not limited to high pressures during dialysis,
154
D. K. Rajan
poor measured ow rates with ultrasound or Transonic measurement (dilution ow measurements at the time of dialysis), swollen arm or neck and face, prolonged bleeding time
after needle removal, painful dialysis, hand or digital ischemia due to potential steal, frequent clotting of dialysis lines,
and inadequate dialysis. Angiographic/ultrasound criteria is
>50% luminal narrowing.
Ultrasound can be used to diagnosis sites of stenosis and
thrombosis and equally guide needle access into the graft or
stula. However, ultrasound is not suitable for assessing the
central veins. The primary imaging modality for evaluating
the entirety of the access circuit, from artery to atrium, is
catheter angiography. While CT and MRI have been
described, both these modalities are costly and time-consuming and do not allow intervention.
Approach for stulography in stulas is more variable
than in grafts given the variability of location of lesions in
different types of stulas. Physical examination and sonography help determine where stenoses and guide access points
for catheter insertion. Generally, for radiocephalic stulas,
the stula should be punctured toward the arteriovenous
anastomosis. For brachiocephalic stulas, if the stula is
pulseless, puncture toward the anastomosis; if it is pulsatile,
puncture toward the outow. For brachiobasilic stulas,
puncture toward the outow. A unique approach for imaging
and intervention is via the radial artery which provides access
to the inow artery and venous outow of stulas [9].
For stulography of grafts, access is obtained near the
arterial anastomosis since most stenoses occur downstream
within the graft, at the venous anastomosis, or in the arm or
central veins. Nevertheless, the arterial anastomosis is always
assessed. This can be done with sonography or by reuxing
contrast backward via (1) manually compressing the venous
limb of the graft while injecting, (2) inating a blood pressure cuff to suprasystolic pressures central to the graft, or (3)
injecting contrast through the sheath when the angioplasty
balloon is inated when treating a venous stenosis. An injection of 10cc of iodinated contrast usually sufces. Diluting
it 50% with normal saline may allow you to “see through”
the contrast to discern areas of stenosis. It is important to
obtain orthogonal views to assess severity of stenosis, see
them in prole, and remove overlapping veins.
Kidney Dialysis Outcomes Quality Initiative (KDOQI) is
a consensus guideline document which outlines treatments
and outcomes for all of end-stage renal care. The last revision was published in 2006 with another revision currently in
development with potential publication in 2018. It is important to know that multiple guidelines are based on retrospective data and, where little exists, based on consensus opinion.
Key outcome guidelines:
• Primary patency rate of 50% at 6months after percutaneous transluminal angioplasty (PTA).
• Surgical revision should be considered if more than two
PTA events of the same lesion is performed within
3months.
• Clinical success rate of 85% with a primary patency rate
of 40% at 3months for percutaneous declotting of dialysis access [6].
Recent prospective studies of angioplasty outcomes have
shown lower patencies than these recommended goals [10–12].
There remains no clear consensus whether routine moni-
toring and interventions improves the overall patency and
useable life of an access. However, there are studies that have
shown a decreased rate of access thrombosis with imagingdriven interventions in patent but failing accesses [13].
Monitoring can be performed with duplex ultrasound or
ultrasound dilution technique (e.g., Transonics).
Conventional Therapy
Historically, conventional therapy included surgical patch
angioplasty or jump grafts. These have largely been supplanted by endovascular interventions such as balloon angioplasty and use of stent grafts or stents.
Interventional Therapy
AVG Angioplasty
Stenosis is most commonly found at the venous anastomosis
between the distal end of the dialysis graft and the outow
vein (~70%) (Fig.12.4). The stenosis is caused by neointimal hyperplasia which is composed of collagen, broblasts,
and smooth muscle cells. Over time, the stenosis progresses
continually narrowing the outow channel until stasis results
in thrombosis. Stenosis can also occur anywhere within the
access circuit from subclavian artery through the access and
to the superior vena cava.
The most common treatment of stenosis is balloon angio-
plasty. An angioplasty is considered successful when there is
<30% residual stenosis and the clinical indication for intervention has resolved. Ideally, the balloon diameter should be
equal to or 10% larger than the non-stenosed vessel or graft
located before or after the stenosis. The balloon length
should sufciently cover the length of the lesion plus 1cm
beyond the lesion to prevent “watermelon seeding” or slippage of the balloon during ination. In most cases, operators