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Angioplasty/Stenting of the Subclavian and Axillary Arteries 201
Procedure
Arterial Access
• Subclavian and axillary artery lesions may be approached from either the brachial
or the femoral approach, or a combination of the two.
• Femoral artery access is performed in a standard fashion.
• In the presence of a subclavian or axillary artery stenosis or occlusion, the
brachial pulse downstream to the lesion is likely to be either weak or impal-
pable. Therefore, ultrasound should be used as guidance to puncture the artery.
In the past, when most delivery systems for stents were greater than 6F, a formal
cut-down was used for brachial access. This is no longer necessary, but may be
used if ultrasound guidance is either unsuccessful or not available.
Angiography
• Diagnostic angiographic images can be obtained using conventional catheter
techniques, MRA or CTA.
• Prior to intervention, catheter angiography should be performed, using a pigtail
catheter, placed in the aortic arch.
Assessment should be made of the following:
• Whether the lesion is an occlusion or a stenosis
• The relationship of the lesion to important side branches (most notably the
vertebral artery and the internal mammary artery)
• The lesion morphology
• The hemodynamics of the lesion, particularly if there is reverse flow in the
vertebral arteries.
Intra-procedural Medications
• All patients should already be taking the medications described previously, e.g.,
Statin, antiplatelet medication, and antihypertensive medication (as required).
• Patients should receive intra-procedural doses of short-acting anticoagulant drugs
(such as heparin) to ensure that they remain anticoagulated for the duration of the
procedure to prevent pericatheter thrombosis and thrombosis of arterial segments
which have stasis of flow during balloon inflation.
202 T.J. Cleveland
Assessing the Lesion
Morphology
• Stenoses are technically easier to treat than occlusions.
• During angioplasty and stenting, atheromatous material may be dislodged along
the wall of the artery, thus close proximity of side branches may result in
compromise of those side branches.
• Heavily calcified lesions, particularly occlusions may be very resistant to
endovascular treatment, both in terms of the ability to cross the lesion with a
guidewire and resistance to expansion by balloons and stents.
Location
• Lesions located at the origin of the subclavian or brachiocephalic arteries may
be very difficult to engage from a femoral approach, reducing the chances of
successful recanalization.
• Close proximity of the lesion to the vertebral artery may result in vertebral artery
compromise during angioplasty or stent placement.
• Lesions which have a segment of subclavian or axillary artery either proximally
or distally are generally easier to engage with guidewires.
Pressure Measurements
• Pressure measurements are generally of little use for these procedures as the
intention of primary angioplasty (PTA) may not be for flow-limiting disease
(in the context of embolic symptoms). When stents are placed they are sized to
match the arterial diameter outside the lesion and so full expansion is the desired
outcome.
• There are no data to support any prognostic value in measuring intra-arterial
pressures for such procedures.
Choosing a Balloon or Stent
• If balloon angioplasty is the planned procedure, the balloon should be sized to
match the artery just distal to the lesion. Such measurements can be obtained
from a number of sources:
◦ Diagnostic CTA or MRA
◦ Duplex
◦ Calibrated catheter angiography
• If the primary intention is to place a stent, or a stent is used for a failed PTA,
then the intended stent diameter should match the adjacent artery. For a balloon-
mounted stent, these diameters should be the same. For a self-expanding stent,
the unconstrained diameter should be 1–2 mm larger than the index artery.
Angioplasty/Stenting of the Subclavian and Axillary Arteries 203
• If the arterial segment is not likely to be subject to compressive forces, and
accurate placement is needed, then balloon-mounted stents are generally favored.
If recovery from compressive forces is likely to be important, then a self-
expanding stent must be used.
Performing the Procedure
Crossing the Lesion
• Stenoses are technically less challenging than occlusions.
• Stenoses may be approached from either the brachial or the femoral approach.
◦ Generally, they are easier to traverse if they are approached from a smaller
diameter artery, i.e., from the brachial approach.
◦ In addition, the crossing of such lesions may be less likely to cause any asso-
ciated thrombus to be dislodged if approached from a brachial access. This is
of particular importance when treating lesions in the brachiocephalic artery,
where any emboli produced will potentially travel to the cerebral circula-
tion and cause a stroke. In such circumstances, the use of cerebral protection
devices may be advantageous.
• Subclavian and axillary artery occlusions usually arise from the formation of
chronic plaque which is both well organized and often calcified. As a result they
are very resistant to traverse with a guidewire.
◦ To achieve success, these lesions may need to be approached from both the
brachial and femoral approach (Fig. 4). The intimal lining of the occluded
artery is destroyed by the disease process and the guidewire is likely to pass in
a plane within the media of the arterial wall.
• If the lesion lies close to the origin of an important branch artery, consideration
should be paid to protection of this vessel, by passing a wire or balloon into this
artery during treatment of the primary lesion.
Fig. 4 A diagrammatic
representation of a combined
approach to a brachiocephalic
occlusion from both a femoral
and brachial approach
204 T.J. Cleveland
Deploying the Balloon/Stent
• Balloons and stents should be selected to obtain the desired diameter of the target
artery and should be of sufficient length to cover the lesion.
• If the selected stent is not long enough to cover the lesion, additional stents should
be available to adequately cover the lesion. Additional stents should be placed
with an overlap of at least 1 cm.
• It is important to have the facility to perform angiograms before and after PTA or
stent insertion. This is generally achieved by the placement of a pigtail catheter
in the aortic arch, usually from a femoral approach.
Endpoint
• If the original symptoms were of embolic origin, the primary intention is to per-
form PTA and to stimulate the arterial lining to heal with a smooth neointima.
Thus the aim of the procedure is not for a perfect hemodynamic result, although
the flow through the segment must be sufficient to prevent a significant risk of
acute thrombosis. Once PTA has been performed the arterial wall must be allowed
sufficient time to heal.
• If the original symptoms were the result of poor blood flow, then the primary
intention is to remove the hemodynamic lesion. This may be achieved by PTA or
stent placement. For stenotic lesions, either strategy is reasonable, as there is no
definite difference in outcomes between PTA and stents. However, for occlusions,
the results of primary stenting are better than PTA. Therefore, the lesion should
be stented with the intention of achieving as small a residual stenosis as possible.
Immediate Post-procedural Care
• The access points should be closed.
◦ In the ante cubital fossa, this should be achieved by application of digital
pressure.
◦ A closure device may be used to seal a femoral artery puncture.
• The access points should be observed for bleeding or hematoma, and the patient’s
vital signs should be monitored.
• Stroke may occur both during these procedures and in the immediate post-
operative period. Routine neurological observations should be undertaken.
• There is no need to continue heparin after completion of the procedure, but
antiplatelet medication should not be interrupted.
Follow-Up and Post-procedure Medications
• These procedures may be performed on a day case basis, provided that patients
are observed for at least 4 h after their procedure, and are discharged to a
safe environment (responsible company, telephone availability, information sheet
Angioplasty/Stenting of the Subclavian and Axillary Arteries 205
regarding complications to be aware of, a point of contact at the treating hospital
available 24 h a day).
• Statins, anti-hypertensives, and antiplatelet agents should be continued indefi-
nitely.
Results
• There are few series of significant size in the literature and no randomized trials.
• The success at crossing complete occlusions is variable ranging from 30 to 94%.
• The patency results for treated stenoses are generally better than those for occlu-
sions and stent series report higher patency than PTA series. However, the vast
majority of series contain a wide range of lesion and treatment types, making it
difficult to draw definite conclusions regarding the efficacy of PTA versus stents.
• Primary patency of 80% at 6 and 16 months are described along with patency of
75% at 8 years. Other series describe less durable results.
Alternative Therapies
• Conservative therapy with best medical management should be considered for
relatively minor symptoms.
• Open surgery (bypass, transposition, or endarterectomy) are alternatives.
Complications
• Complications include
◦ Acute stent/PTA thrombosis
◦ Stroke
◦ Arm emboli
◦ Access site hematoma
How to Treat
• Acute stent/PTA thrombosis may be treated by thrombectomy, thrombolysis, or
surgical bypass.
• Stroke may be hemorrhagic or embolic and should be investigated by CT or MRI.
◦ Thrombolysis may be considered in the hyperacute phase of embolic stroke.
◦ Reversal of anticoagulation.
◦ Cessation of antiplatelet agents in the case of hemorrhagic stroke.
• Distal embolization to the arm is often asymptomatic. If patients are symp-
tomatic, they may be treated by aspiration or Fogarty embolectomy.
206 T.J. Cleveland
How to Avoid
• Avoidance is largely dependent upon good technique, drug therapy, effective
planning, and not treating morphology poorly suited to PTA/stenting.
Key Points
• Review symptoms and ensure that the procedure is indicated.
• Ensure that the pre-procedural imaging is adequate, take time to plan the
procedure, and check that all the appropriate equipment is available.
• Know how to use all of the equipment.
• Ensure that the patient is taking appropriate drug therapy.
• Limit manipulation of the lesion to a minimum by use of the brachial
approach.
• Consider cerebral protection if embolization to the brain is a possibility.
• Have a low threshold for seeking the advice/help of someone with a large
experience of the treatment of these lesions.
Suggested Reading
1. Kessel D, Robertson I. Interventional Radiology: A Survival Guide – 2nd Edition. Elsevier.
2. Przewlocki T, Kablak-Ziembicka A, Pieniazek P, et al. Determinants of immediate and long-
term results of subclavian and innominate artery angioplasty. Catheter Cardiovasc Interv 2006;
67: 519–526.
3. Rutherford RB (Ed) Rutherford Vascular Surgery – 6th Edition. Elsevier 2008, Chapter 90.
4. The Royal College of Radiologists (2005). Standards For Iodinated Intravascular Contrast
Agent Administration To Adult Patients. Royal College of Radiologists, London. http://www.
rcr.ac.uk
5. Woo EY, Fairman RM, Velazquez OC, et al. Endovascular Therapy of Symptomatic
Innominate-subclavian Arterial Occlusive Lesions. Vasc Endovasc Surg 2006; 40: 27–33.
Stent-Grafting of the Thoracic Aorta
Jean-Paul Beregi and Marco Midulla
Clinical Features
Thoracic endovascular repair is often known by the acronyms TEVAR or TEVR.
The technique was introduced in the early 1990s and has become increasingly
used worldwide to treat a variety of aortic pathologies.
Types of the Pathology Treated by TEVR
• Thoracic aortic aneurysm (TAA): These include atherosclerotic aneurysms, post-
traumatic false aneurysms, anastomotic pseudoaneurysms post-aortic surgery,
mycotic aneurysms, and pseudoaneurysms post-coarctation repair.
• Acute Aortic Syndromes (AAS): Aortic dissection, Intramural Hematoma (IMH),
and penetrating aortic ulcer (PU).
The term AAS was introduced in 2001 to describe acute chest pain related to three
acute aortic pathologies:
• Chronic aortic dissection
• Acute Traumatic Aortic Rupture (ATAR)
• Aortobronchial fistula
Diagnostic Evaluation
Clinical
Most aortic pathology is silent until there is evidence of rupture or impending
rupture:
• The majority of aortic lesions are discovered by chance as a result of chest
radiography, MRI or CT examinations performed for other clinical indications.
207
R.A. Morgan, E. Walser (eds.), Handbook of Angioplasty and Stenting Procedures,
Techniques in Interventional Radiology, DOI 10.1007/978-1-84800-399-6_17,
C
Springer-Verlag London Limited 2010
208 J.-P. Beregi and M. Midulla
• Chest pain in the presence of a known aortic lesion suggests impending or
established rupture.
• Established rupture is usually accompanied by severe chest pain, hypotension, or
death.
Laboratory
Clearly aortic rupture is usually accompanied by a fall in the serum hemoglobin.
• In acute dissection or IMH, involvement of the renal and other visceral branches
may be accompanied by deterioration in renal function and serological signs of
intestinal ischemia such as an increase in lactate dehydrogenase.
Pre-interventional Imaging
It is essential to review the preoperative imaging to
• Identify the nature of the aortic pathology
• Assess the indications, if any, for treatment
• Decide a plan for therapy
The main non-invasive modalities used for the evaluation of the thoracic aorta are
chest radiography, CT, and MR imaging.
Chest Radiography
Assess chest radiographs performed for other indications for signs of aortic
pathology.
• Observe for enlargement of the thoracic aorta and signs of rupture: mediastinal
widening, left pleural effusion.
CT and CTA
The main imaging method used for the assessment of the thoracic aorta.
• The scan should cover the entire aorta commencing above the aortic arch and
extending inferiorly to include the abdominal aorta and the iliac arteries as far as
the inguinal ligament.
Stent-Grafting of the Thoracic Aorta 209
• Use multiplanar reconstructions (MPRs) and view the maximum intensity pro-
jection (MIP) images on the CT workstation to assess:
b
Location and extent of the aortic lesion
b
For the presence of proximal and distal landing zones for an endograft(s)
b
The configuration of the aorta and iliac vessels with regard to tortuosity
and kinking which might cause problems in delivery of the endograft to the
required site
b
The access site and iliac arteries for their diameter, amount of calcification,
and the presence of aneurysms
• Diameter measurements of the aorta should always be made orthogonal to the
vessel. This is most easily done using the reformatted images. If only axial
images are available, the diameter of the short axis of the vessel should be
measured.
• The following diameter measurements should be obtained:
b
The maximum diameter of the aorta.
b
The diameter of potential landing zones for an endograft proximal and distal
to the aortic lesion.
b
The diameter of the access vessels − i.e., the iliac and common femoral
arteries.
• Length measurements are best made using oblique sagittal or curved reformatted
images.
• The following length measurements should be obtained:
b
The length of the aneurysm if present
b
The length of normal diameter aorta proximal and distal to the aortic lesion
(landing zones)
MRI and MRA
Less commonly used than CT for pre-procedural imaging for TEVR:
b
A combination of MRI and MRA is best.
b
Gated scans improve image quality.
b
Axial coverage from the aortic arch to the iliac arteries is not possible.
The necessary measurements required when planning TEVR are summarized in
Table 1 and Fig. 1.
210 J.-P. Beregi and M. Midulla
Ta bl e 1 Preoperative measurements required when planning for TEVR
D1 a Aortic diameter proximal to the lesion 2 cm proximal to the lesion
D1 b Immediately proximal to the lesion
D2 The diameter of the aortic lesion
D3 a Aortic diameter distal to the lesion Immediately distal to the lesion
D 3 b 2 cm distal to the lesion
L1 Proximal neck length
(proximal landing zone)
Distance of lesion-LSCA;
or distance of lesion-LCA;
or distance of lesion−innominate artery
or distance of lesion−aortic sinotubular
junction
L2 Length of the lesion
L3 Length of the distal neck
(distal landing zone)
Usually distance from lesion−coeliac trunk
D4 Iliac artery diameters Right and left
Fig. 1 An example of a diagram used for planning for TEVR