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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3955_Библиотеки_им_академика_М_И_Перельмана.pdf
Subintimal Angioplasty
Guy Fishwick
Clinical Features
• In most centers in the UK, the majority of patients treated by subintimal
angioplasty have critical limb ischemia (CLI):
b
Rest pain
b
Ulceration
b
Gangrene
• Occasionally patients with short-distance intermittent claudication are considered
for treatment.
Diagnostic Evaluation
The aims of diagnostic evaluation are
• To establish ischemia as the cause of the symptoms and signs
• To establish the extent and level of the vascular occlusion
• To establish the proximal and distal extent of the lesion
Clinical
The following should be assessed:
• Risk factors:
b
Diabetes
b
Smoking
b
Hypertension
b
Duration of symptoms
b
Previous circulatory problems/investigations/surgery
111
R.A. Morgan, E. Walser (eds.), Handbook of Angioplasty and Stenting Procedures,
Techniques in Interventional Radiology, DOI 10.1007/978-1-84800-399-6_10,
C
Springer-Verlag London Limited 2010
112 G. Fishwick
• The degree of ischemia:
b
Presence/absence of pulses
b
Skin changes
b
Tissue loss
b
Concomitant venous problems
b
Capillary circulation in the foot
b
ABPI
Laboratory
The following should be assessed:
•Hb
•INR
• Renal function
• Glucose
• (Thrombophilia screen in selected cases)
Imaging
One of the following (or a combination) should be performed:
• Duplex ultrasound:
b
This is the main initial imaging method performed in most vascular depart-
ments in the UK.
b
Adequate information regarding the femoropopliteal segment and tibial arter-
ies can be obtained in the vast majority of patients.
b
Although duplex ultrasound is reasonably good in the assessment of the iliac
arteries, excessive abdominal wall fat or bowel gas can obscure these vessels
in such patients.
• CT angiography:
b
This is being increasingly used as a non-invasive alternative to conventional
angiography.
b
The advantage over duplex is the provision of a series of images of the arterial
tree in an “angiographic format.”
Subintimal Angioplasty 113
b
The requirement for ionising radiation and iodinated contrast medium are
obvious disadvantages.
b
Heavy vascular calcification may obscure the view of the vessel lumen and
reduce the usefulness of this modality in such patients.
• MR angiography
b
Also used more and more as an alternative to conventional angiography.
b
A moving table is required for peripheral MRA.
b
The disadvantages of heavy calcification, ionizing radiation, and iodinated
contrast medium are not seen with MRA.
b
However, due to the recently recognized syndrome of renal nephrosclerosis
related to MR contrast media, MRA is not suitable for patients with marked
renal dysfunction.
• Catheter angiography
b
Remains the gold standard for peripheral vascular imaging.
b
The main disadvantage, apart from ionizing radiation and iodinated contrast
media, is the invasive nature of the procedure.
Indications
• Critical limb ischemia due to occlusive arterial disease or long diffuse stenotic
arterial disease.
• A relative indication is short-distance intermittent claudication due to occlusive or
long-segment stenotic arterial disease. However, the management of claudication
in most cases should be conservative i.e., advice regarding lifestyle change and a
program of exercise.
Contraindications
• Recent arterial occlusion.
• Popliteal aneurysm.
• A relative contraindication is the presence of significant common femoral artery
disease in the affected leg.
Patient Preparation
• Standard skin preparation.
• If the patient has renal impairment, preangiographic hydration should be provided
(+/– N-acetyl cysteine).
114 G. Fishwick
• It is important that the patient is able to lie still for the duration of the procedure.
• Standard aseptic preparation should be used.
Relevant Anatomy
Symptoms are produced by arterial disease at any level from the aorta to the crural
(tibial) vessels.
• As a rule, the more proximal lesions should be treated before distal lesions.
• If a distal lesion is treated in isolation (ignoring a proximal lesion), the result will
not be durable.
• Common femoral artery access is usual and preferable.
• Brachial artery access is an option, but is not a good access route for lower limb
subintimal angioplasty.
b
A very long relatively rigid sheath will be required; even then getting adequate
“push” through a lesion will be difficult.
Aberrant Anatomy
The following variants of normal anatomy are noteworthy for IRs undertaking lower
limb subintimal angioplasty:
• A high bifurcation of the femoral artery above the inguinal ligament − which
causes difficulties in antegrade common femoral artery puncture
• A high origin of the posterior tibial artery from the popliteal artery
• A hypoplastic anterior tibial artery with the dorsalis pedis artery supplied from
the peroneal artery
Specific Equipment
The following are the basic tools required to perform subintimal angioplasty and to
deal with complications:
• A 0.035-inch guidewire with a relatively short tip, which can be shaped
• Short length angled-tip catheter (approximately 15–30-cm long)
• Sheaths with removable hemostatic valves
• Angioplasty balloons (over-the-wire balloons, 0.035 inch) of a range of appropri-
ate sizes
• A re-entry catheter (e.g., Outback (Cordis, Europe))
Subintimal Angioplasty 115
• Wide bore straight aspiration catheters
• Stents and stent grafts
Pre-procedure Medication
• None specific to this procedure.
• Patients on warfarin should be converted to heparin until their INR is at an
appropriate level − usually below 1.5.
• For patients on clopidogrel − review the indication for the prescription and
discontinue if appropriate.
• Continue antihypertensive agents and medication for diabetes (metformin should
be stopped at the time of the angioplasty and should not be restarted until the
renal function has been checked post-procedure)
Procedure
Access
The following are suggestions for optimal access to approach lesions in different
anatomical locations:
• Ipsilateral antegrade common femoral artery puncture for superficial femoral,
popliteal, and crural artery lesions.
• Ipsilateral retrograde or contralateral retrograde common femoral artery puncture
for iliac artery access.
• Contralateral retrograde common femoral artery puncture for superficial femoral,
popliteal, and crural lesions in obese patients.
• Ipsilateral retrograde popliteal artery access is also an option for superficial
femoral artery (SFA) lesions in obese patients or for problematic flush SFA
occlusions.
• Ipsilateral retrograde popliteal artery access is also an option if recanalization
from the antegrade direction fails.
Angiography
• Digital subtraction angiography (DSA) is used to confirm the pre-procedural
imaging findings.
• This is usually achieved by hand injection, unless the lesion involved is a common
iliac artery occlusion to be recanalized from the aorta.
• Be sure to check that there is no fresh occlusion of arteries that were patent on
pre-procedure imaging.
116 G. Fishwick
Intra-procedural Medication
• Heparin is given prior to creating a dissection i.e., the s ubintimal track (approxi-
mately 50 IU/kg).
• GTN 100–150 mcg given intra-arterially by bolus injections may be given into
any vessel that goes into spasm during the procedure. However, arterial spasm is
rare in this group of patients with generalized arterial disease.
Assessing the Lesion
The following questions should run through the interventionalist’s mind before
beginning the recanalization:
• Where is the most proximal point of the occlusion?
• Is the vessel diseased proximal to the occlusion?
• Is there disease distal to the occlusion? − This will likely affect the level of
re-entry into the lumen from the dissection.
• Is there multi-level disease?
• What is the quality of the run-off to the foot?
b
How many vessels?
b
Are they diseased?
• If the SFA is diseased throughout its length, is there any indication where t he
SFA origin is located? The SFA origin may be visualized with approximately 30
◦
oblique angulation (LAO for left, RAO for right).
Performing the Procedure
Crossing the Lesion
Antegrade Approach for the SFA, and Distal Vessels but Not Involving the SFA
Origin
• Set up the image intensifier over the lower half of the femoral head, tightly coned,
just showing the needle tip at the top of the image, so that the operator’s fingers
are excluded.
• Perform antegrade CFA puncture.
• Inject contrast through the needle (Fig. 1).
• Identify the SFA origin and confirm that the puncture is sufficiently proximal to
the origin to manipulate either the guidewire or an angled-tip catheter into the
SFA.
• Direct the guidewire into the origin and insert a sheath over the wire.
Subintimal Angioplasty 117
Fig. 1 Contrast injected through the needle or short introducer confirms puncture of the common
femoral artery above its bifurcation and the location of the SFA origin
• If the SFA origin is not easily accessed with the guidewire, the wire should be
passed into the profunda femoris artery.
b
An angled-tip catheter should be passed into the profunda.
b
The angled-tip catheter should be pulled back almost to the profunda origin.
b
Perform a roadmap through the angled-tip catheter to define the location of
the CFA bifurcation and the course of the SFA.
b
Using the roadmap, and by rotating the catheter, select and advance a
hydrophilic guidewire into the SFA
b
Advance the catheter over the wire into the SFA.
• Perform selective angiography as above.
• Select the point of origin of dissection.
Select the preferred segment of vessel distal to the occlusion i.e., where to end the
dissection
◦ This segment should ideally be disease free.
118 G. Fishwick
• Initiate the dissection channel above the occlusion, by pushing the wire tip and/or
the tip of the angled-tip catheter into the vessel wall.
• If this is difficult (not common), i ntimal tears can also be created by inflation of
a balloon in the artery above the occlusion.
• Introduce the catheter tip into/under the tear. The location in the subintimal space
can be confirmed by injection of a very small (0.5 mL) injection of contrast
medium, although this is seldom necessary (Fig. 2).
A dissection is seen as a linear contrast blush in the arterial wall, often with
contrast medium washed away in small rete veins in the wall, and then into the
venae commitantes.
• Introduce the hydrophilic guidewire tip further into the dissection.
• Push the tip forward until it curls into a loop.
• Using a gentle forward and backward (nudging) action, advance the loop of the
wire down the vessel alongside the occlusion.
• The wire will tend to advance in a spiral in the artery wall (Fig. 3).
• Support the wire with a catheter (or a balloon catheter) advanced behind the loop.
• If the balloon catheter/guidewire fails to advance in any area, the balloon can be
inflated in the area to facilitate passage.
Fig. 2 Contrast injection to
confirm creation of a
dissection
Subintimal Angioplasty 119
Fig. 3 Wire supported by
balloon catheter, looped and
advanced, spiraling around
the intimal calcification
Re-entry
• When the loop reaches the preferred area for re-entry into the lumen, advance the
catheter to this area.
• Remove the wire and inject a small volume of contrast to see whether:
a The catheter tip is still within the dissection (no flow).
b The catheter tip is in the vessel lumen (rapid flow away in normal vessel).
120 G. Fishwick
c The catheter tip is still within the dissection, but there is communication
with the lumen (lingering contrast around the catheter tip, which rapidly
flows away into the normal vessel nearby).
• If the situation is scenario c, the wire tip should be introduced into the vessel
lumen using the roadmap facility.
• If the situation is scenario b, with no communication demonstrated from the dis-
section to the lumen, recreate the loop on the guidewire but only with the floppy
portion of the wire.
b
Using the same nudging movement, advance the wire a little further down the
dissection.
b
While advancing and withdrawing the loop, roll the wire between the thumb
and forefinger to spin the looped tip.
b
If re-entry to the lumen is still not achieved, a decision is needed as to whether
to continue the dissection distally, or to use a re-entry catheter to limit the
length of the dissection (see below).
• When re-entry occurs, the guidewire will move freely in the arterial lumen and
the guidewire loop may also appear smaller as it is now constrained within the
smaller arterial lumen.
Re-entry Catheters
Two catheters are available to facilitate re-entry into the lumen below an occlusion.
• The Outback catheter − Cordis, Europe.
• The Pioneer catheter − Medtronic, Santa Rosa, CA.
Both catheters have a curved needle near the tip, which can be advanced out of
the side of the tip of the catheter and then retracted. These catheters are introduced
over a 0.014" guidewire.
• The Outback catheter relies on a shaped marker at the tip to show the needle
position and orientation on fluoroscopy.
• The Pioneer catheter has an IVUS probe within the tip to visualize the vessel
lumen and to guide the advance of the needle tip.
Once the retractable needle has been advanced into the lumen, the guidewire is
advanced and the catheter is exchanged for the balloon catheter.
The dissection channel is angioplastied as before.