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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3955_Библиотеки_им_академика_М_И_Перельмана.pdf
314 H. Bjarnason
b
Surgeons often create small arteriovenous fistulae in conjunction with large
vein surgical bypasses in order to improve patency in these low flow vessels.
Complications
• Complications of venous angioplasty and stent placement are few:
• Bleeding complications are surprisingly rare. We have encountered procedure-
related hemodynamically significant bleeding and venous perforation in the face
of recent:
b
External beam radiation therapy
b
Surgery, such as regional lymph node dissection
• There are reported deaths from exsanguination or pericardial tamponade due
to iatrogenic rupture of the SVC. Thus, the operator should be prepared to
act quickly if patients deteriorate immediately or soon following SVC stent
placement.
How to Treat
• Keep in mind that you can diagnose pericardial tamponade quickly with ultra-
sound and immediate placement of a pericardial drain is usually the treatment. A
covered stent or surgery may be required if pericardial hemorrhage is persistent.
• Re-inflate the balloon in the SVC if extravasation occurs to halt active bleeding
and prepare to place a covered stent or initiate surgical repair if extravasation
persists after 15–30 min of balloon inflation.
How to Avoid
• Be careful in areas of previous radiation treatment or surgical intervention
especially if recent dissection or radiation was directed toward the target vein.
Consider a covered stent if treatment is absolutely necessary.
• Pericardial tamponade is hard to avoid. The length of the pericardial reflection
varies much and can extend to the innominate vein confluence:
b
Be careful not to over dilate. We dilate rarely beyond 14 mm.
b
The primary use of covered stents may be an option.
Key Points
• Good inflow is a key requirement for s uccessful venoplasty and stent place-
ment. If the inflow is impaired, the treated segment will likely occlude
(Fig. 2)
Venoplasty and Stenting 315
• Larger stents do better than smaller ones. Therefore, oversize by 10–20%
compared to the normal-sized vessel.
• If the lesion exhibits significant recoil, consider placing stents with added
support. Use balloon-expandable stents with their better radial force in
deeply guarded locations as in the chest or pelvis.
• Be prepared to quickly respond to hemothorax or hemopericardium when
dilating or stenting SVC stenoses, especially if the area has been radiated
or surgically manipulated within the last 2–3 months.
Suggested Reading
1. Barshes NR, Annambhotla S, El Sayed HF, et al. Percutaneous stenting of superior vena cava
syndrome: Treatment outcome in patients with benign and malignant etiology. Vascular 2007;
15(5): 314–321.
2. Ganesha A, Quen Hon L, Wrakaulle DR, et al. Superior vena caval stenting for SVC
obstruction: Current status. Eur J of Radiol 2009; 71(2): 343–349.
3. Mussa FF, Peden EK, Zhou W, et al. Iliac vein stenting for chronic venous insufficiency. Tex
Heart Inst J 2007; 34(1): 60–66.
4. Neglen P, Raju S. In-stent recurrent stenosis in stents placed in the lower extremity venous
outflow tract. J Vasc Surg 2004; 39(1): 181–188.
5. Neglen P, Thrasher TL, Raju S. Venous outflow obstruction: An underestimated contributor to
chronic venous disease. J Vasc Surg 2003; 38(5): 879–885.
Venous Thrombolysis and Thrombectomy
for Deep Venous Thrombosis
Nael E. A. Saad and Suresh Vedantham
Clinical Features
• Venous thromboembolism (VTE) has an incidence of nearly 1 million cases per
year in the United States alone. VTE encompasses deep vein thrombosis (DVT)
and pulmonary embolism (PE) [1].
• Table 1 outlines the major risk factors for developing VTE.
• Although many DVT cases are clinically silent, DVT patients usually experience
limb swelling, cramping, and/or pain:
b
With modern DVT care, commonly delivered in outpatient fashion, these
presenting DVT symptoms may often be under managed from the affected
patient’s perspective.
• 85–90% of DVT cases involve lower extremity veins and 10–15% involve upper
extremity veins.
• Lower extremity DVT is divided into several categories:
b
Isolated Calf DVT (“distal DVT”) is associated with a low risk of causing
PE. However, a minority of calf DVT cases will eventually propagate into the
popliteal vein if untreated.
b
Proximal DVT, defined as DVT involving the popliteal vein and/or more
cephalad deep veins, is associated with relatively high risk of PE.
b
Iliofemoral DVT refers to proximal DVT that involves the iliac vein and/or
the common femoral vein. Iliofemoral DVT tends to cause more severe acute
symptomatology, and is associated with a significantly higher risk of the Post-
Thrombotic Syndrome (PTS) [2].
• Consequences of Venous Thromboembolism:
b
Early complications of acute DVT include
PE is the presenting manifestation in approximately one-third of VTE
cases and is estimated to cause more than 100,000 deaths per year in the
United States alone [1].
317
R.A. Morgan, E. Walser (eds.), Handbook of Angioplasty and Stenting Procedures,
Techniques in Interventional Radiology, DOI 10.1007/978-1-84800-399-6_24,
C
Springer-Verlag London Limited 2010
318 N.E.A. Saad and S. Vedantham
Ta bl e 1 Major risk factors for developing DVT
Major risk factors for developing DVT
• Previous DVT or PE
• Orthopedic surgery of the lower extremity
• Major surgical procedure
• Increased patient age
• Malignancy
• Obesity
• Major trauma
• Congestive heart failure, myocardial infarction
• Estrogen therapy
• Immobilization
• Inherited thrombophilia
Paradoxical embolization, a rare condition in which a deep venous throm-
bus passes through an intracardiac shunt to enter the arterial circulation,
may cause devastating complications, including stroke.
Phlegmasia cerulea dolens, a rare condition in which DVT causes mas-
sive swelling of the entire extremity, can lead to arterial insufficiency,
compartment syndrome, venous gangrene, and/or limb amputation.
b
Despite use of anticoagulant therapy, complications of acute DVT include
Recurrent VTE episodes (5–10% per year for most subgroups) [3]
Chronic thromboembolic pulmonary hypertension.
Post-Thrombotic Syndrome (PTS) (Table 2)
As a result, acute DVT is actually a chronic disease!
Ta bl e 2 The post-thrombotic syndrome
The post-thrombotic syndrome
• PTS develops in 25–50% of patients with a first episode of proximal lower-extremity DVT
• PTS causes chronic lifestyle-limiting symptoms such as limb swelling, pain, limb
heaviness/fatigue, venous claudication, and stasis dermatitis, and can progress to skin
ulceration
• PTS causes significant quality of life (QOL) impairment in DVT patients. The severity of PTS
parallels the degree of QOL impairment. The health impairment caused by established PTS is
comparable to that of other chronic diseases such as chronic obstructive pulmonary disease
• Because established PTS and venous ulcers are difficult and expensive to treat and often result
in work disability, the disease burden of PTS has major economic consequences to society as
well
• The most consistent risk factor for PTS has been the development of recurrent ipsilateral
DVT. Therefore, pending future studies, adequate anticoagulant therapy should be viewed as
a key PTS prevention measure. However, many anticoagulated patients will still develop PTS
• Daily use of 30–40 mmHg, knee-high, elastic compression stockings (ECS) for 2 years after
DVT decreases the incidence of PTS by about 50% (to around 25%)
Venous Thrombolysis and Thrombectomy for Deep Venous Thrombosis 319
Diagnostic Evaluation
Clinical
• A number of clinical decision tools assist the diagnostic evaluation of DVT. They
incorporate:
b
Clinical suspicion level,
b
Results of imaging tests
b
Laboratory findings.
Laboratory
• A negative D-dimer has a high negative predictive value for DVT.
Imaging
• Duplex ultrasound almost always establishes the diagnosis of extremity DVT
b
High (>95%) accuracy for proximal DVT and moderate (70–80%) accuracy
for isolated calf DVT.
• In patients with DVT i solated to the iliocaval veins, cross-sectional imaging using
CT scan or MR venography may be used. In selected cases, one may resort to
diagnostic venography.
Indications for Endovascular DVT Thrombolysis
• A highly individualized approach to selecting DVT patients for thrombolysis is
recommended [4, 5].
• Urgent first-line endovascular thrombolysis is performed to treat phlegmasia
cerulea dolens or progressive IVC thrombosis (to prevent fatal PE or renal failure
from IVC/renal vein thrombosis).
• Non-urgent second-line endovascular thrombolysis is performed for patients with
symptomatic proximal DVT who exhibit clinical and/or anatomic progression
of DVT on anticoagulant therapy. This may include rapid iliocaval thrombus
extension, exacerabation or persistence of major lower extremity symptoms,
and/or failure to experience sufficient symptom relief to permit ambulation.
• Non-urgent first-line endovascular thrombolysis may be performed to enable
faster symptom relief and/or long-term prevention of PTS in patients with symp-
tomatic, acute extensive proximal DVT. Acute iliofemoral DVT patients are the
best candidates for therapy. However, the risk–benefit ratio of this approach is
uncertain due to a lack of supporting multicenter randomized controlled trials.
320 N.E.A. Saad and S. Vedantham
• Rationale for undertaking endovascular thrombolysis for the prevention of PTS:
b
PTS is caused by the development of ambulatory venous hypertension, which
is thought to be caused by two main factors after an episode of DVT: Valvular
reflux and venous obstruction.
b
Venous thrombosis causes progressive valvular reflux in both involved venous
segments (by direct valvular damage due to the inflammation accompany-
ing thrombosis) and in uninvolved segments (by increasing venous pressures
below the obstruction). Veins in which rapid endogenous clot lysis is observed
tend to develop valvular reflux much less frequently [6].
b
In iliofemoral DVT, complete venous recanalization rarely occurs with anti-
coagulation alone.
b
Small randomized trials of systemic thrombolysis and surgical thrombectomy
have observed reduced rates of reflux, late venous obstruction, and PTS in
proximal DVT patients [7–10].
• Table 3 reviews the contraindications and other factors that impact the deci-
sion process.
Patient Preparation
• If the patient is on warfarin, ensure that the INR is below 2.0 (preferably 1.5)
before starting.
• If the patient has mild-moderate contrast allergy, pre-medicate with steroids and
histamine antagonists.
• In selected patients, placement of a retrievable IVC filter prior to starting therapy
is reasonable:
b
IVC filter is probably unnecessary when infusion-first catheter-directed
thrombolysis (CDT – see below) is used since PE occurs rarely with this
method.
b
The need for IVC filter placement prior to single-session pharmacomechanical
CDT (PCDT) therapy is unclear and may be indicated, especially in patients
with a large thrombus burden.
Anatomical Considerations
• Know the anatomy and proper names of the lower extremity and pelvic veins.
The term “superficial femoral vein” is no longer used – the correct term for this
important deep vein is “femoral vein”.
• Remember that the femoral vein is duplicated in 5–20% of patients
Venous Thrombolysis and Thrombectomy for Deep Venous Thrombosis 321
Ta bl e 3 Major factors that impact the decision process for thrombectomy/thrombolysis of DVT
Factor Good candidate Poor candidate
Life-expectancy Long Short
Activity level Ambulatory before DVT
episode
Non-ambulatory, poor
performance status before
DVT
Bleeding risk profile Low-risk High-risk:
• Intracranial disease (history of
stroke, central nervous system
tumor, aneurysm, arteriovenous
malformation, or other
intracranial lesion)
• Very recent surgery or trauma
• Ongoing pregnancy or very
recent delivery
• Recent gastrointestinal bleeding
or other internal bleeding
• Thrombocytopenia or hepatic
dysfunction
• Severe hypertension
Anatomical extent of
DVT
• IVC Thrombosis
• Iliofemoral DVT
• Isolated calf vein DVT, because
the rate of PTS may be lower in
these patients and the
risk–benefit ratio of
endovascular therapy is
therefore questionable
Symptom duration and
severity
• Acute DVT (less than 2
weeks)
• Rapidly progressive DVT
despite initial anticoagulant
therapy
• Debilitating symptoms
• Asymptomatic DVT, because
they rarely develop PTS
• Chronic femoropopliteal DVT –
lytic therapy ineffective
Signs of circulatory
compromise
• Emergency thrombolysis
unless a strong contraindication
is present; if so, consider the
use of surgical venous
thrombectomy
322 N.E.A. Saad and S. Vedantham
Percutaneous Options for Acute DVT
Catheter-Directed Pharmacological Thrombolysis
(“Infusion-First CDT”)
• Mechanism of action:
b
Direct intra-thrombus drug delivery increases local concentration
b
Drug enhances conversion of plasminogen to plasmin, which cleaves fibrin
• Technique:
b
The basic method [12] of initiating CDT involves several steps:
b
Perform the procedure with conscious sedation with local anesthesia.
b
Access a lower-extremity vein (ideally below the lowest extent of thrombus)
under real-time ultrasound guidance – the popliteal vein and posterior tibial
vein are two commonly used veins, although other veins are also available.
An internal jugular vein can also be used.
b
Use a diagnostic catheter to perform venography and define the clot extent.
b
A multisidehole catheter bridges the thrombosed venous segment and dis-
tributes the infusion of a thrombolytic drug.
b
A new infusion catheter (EKOS, Bothell, WA) emits low power ultrasound
energy during infusion to loosen fibrin strands and speed lysis [13].
• Drug dosing, monitoring, and adjunctive procedures:
b
Urokinase (120,000–180,000 units/h), recombinant tissue plasminogen acti-
vator (0.5–1.0 mg/h), reteplase (0.50–0.75 units/h), or tenecteplase (0.25–
0.50 mg/h) are used for infusion-CDT [4].
b
The drug is infused continuously through the catheter, and concomitant
unfractionated heparin is given at subtherapeutic levels (300–600 units/h)
b
Hematocrit, PTT, and platelet count evaluated every 6 h. You can monitor the
Fibrinogen level, although there is no data establishing its value.
b
Patients transfer to an ICU or step-down unit. If active bleeding occurs or if
the PTT is subtherapeutic, discontinue the infusion.
b
Re-assess lytic progress venographically at 8- to 16-h intervals.
b
If only partial thrombolysis occurs, an angioplasty balloon can be used to
macerate the softened residual thrombus to increase its surface area and speed
the thrombolytic process. Thrombolytic infusion is then continued.
b
After thrombolysis is completed, repeat venography and venoplasty any
visualized stenoses or consider venous stent placement. Repeat venography
confirms patency of the venous system.
b
Full-dose anticoagulant therapy is re-started and patients’ transition to long-
term oral vitamin K-antagonist therapy ( warfarin) and are asked to wear
30–40 mmHg graduated compression stockings for PTS prevention [14].
Venous Thrombolysis and Thrombectomy for Deep Venous Thrombosis 323
• Results:
b
80–90% of patients with acute DVT (symptom duration <2 weeks) achieve
significant clot lysis and marked relief of symptoms [11].
b
Three comparative studies suggest that successful CDT results in prevention
of valvular reflux, late venous obstruction, and PTS. However, none of these
studies were multicenter randomized controlled trials [15–17].
b
In a large multicenter venous registry, infusion CDT was associated with
major bleeding in 11% of patients, and with intracranial bleeding in 0.4%
[11]. Successful thrombolysis required an average of 48 h infusion with 1–3
days ICU monitoring.
Stand-Alone Percutaneous Mechanical Thrombectomy(PMT)
• Mechanism of action:
b
“Aspirating” devices aspirate and remove thrombus from the venous lumen
b
“Non-Aspirating” devices macerate thrombus into tiny fragments, which are
spontaneously lysed by the body
• Advantage:
b
Can perform in patients with contraindications to the use of fibrinolytic drugs
• Disadvantages:
b
Increased on-table procedure time
b
Potential for displacing thrombus with mechanical manipulation:
Increased risk for PE, paradoxical embolus
b
Theoretical potential for causing venous valve injury
• Technique:
b
Varies among available devices. The AngioJet (Possis Medical, Minneapolis,
MN) is an FDA-approved device for removal of iliac and femoral vein throm-
bus. It features a mainframe unit attached to a 5–6 French rheolytic catheter.
The catheter advances to-and-fro over a guidewire within the clot while
depressing a foot pedal. If it is necessary to direct the device to various
positions within a clotted vein, a guiding catheter may be used.
• Results:
b
In general, the available aspirating-type devices do not remove sufficient
thrombus to be therapeutically useful in DVT.
b
The non-aspirating devices (without placement of an inferior vena cava (IVC)
filter) can result in symptomatic PE.
324 N.E.A. Saad and S. Vedantham
b
For these reasons, the use of stand-alone PMT is generally restricted to
patients with clinically severe DVT in whom fibrinolytic drugs are contrain-
dicated:
Consider the use of retrievable IVC filters when treatment is undertaken
under these circumstances.
Pharmacomechanical Catheter-Directed Thrombolysis (PCDT)
• Mechanism of action:
b
Combine both mechanisms of action for CDT and PMT
b
All available devices macerate thrombus and thereby increase the surface area
of residual thrombus and improve thrombolytic drug dispersion within the
thrombus
• Advantages:
b
Accelerates thrombolysis, reducing drug dose and infusion time by 40–50%
b
Reduces ICU utilization, which may reduce hospital costs
b
Newer techniques may enable complete DVT treatment in a single proce-
dure session, which eliminates the need for prolonged drug infusions or ICU
monitoring
• Disadvantages:
b
Thrombolytic drugs contraindicated in patients with a high-risk bleeding
profile.
b
The disadvantages of PMT are also present with PCDT
• Technique:
b
Older “first-generation” PCDT techniques involve a sequential use of infusion
CDT with PMT:
For example, after a short (6–18 h) CDT infusion, PMT can be used to
clean up residual thrombus, shorten treatment time, and reduce drug dose.
Or, initiate therapy with PMT to debulk the thrombus, followed by infusion
CDT to clean up.
b
With ‘‘Powerpulse PCDT’’, the Angiojet [18] is used to forcefully pulse-spray
a bolus dose of thrombolytic drug into the thrombus. The drug dwells in the
clot for 20–30 min, then the Angiojet is used to aspirate the residual softened
thrombus.
b
With ‘‘Isolated Thrombolysis’, the Trellis Peripheral Infusion System
(Bacchus Vascular, Santa Clara, CA) is used [19]. This device features two
catheter-mounted balloons that “isolate” a segment of vein for treatment after
the balloons are inflated.