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Renal Artery Angioplasty and Stenting 151
• Renal artery dissection.
b
Occurs when the wire used to cross the stenosis tracks under the intimal sur-
face. These often will resolve after the stent has been placed but care must be
taken to ensure that the wire is in the true lumen proximal and distal to the
dissection.
b
Prolonged inflation of 3 min or longer can be used to tack down the dissection.
• Renal artery rupture occurs when the renal artery is over-dilated either during
predilation or stent deployment.
b
This can be treated with prolonged balloon dilation or covered stent.
b
Rarely may result in gross rupture requiring balloon tamponade of the renal
artery stump or aorta and emergent surgical repair.
• Renal artery spasm is caused by introduction of the wire into a tiny intrarenal
artery.
b
Treated with infusion of 100-µg nitroglycerin.
b
Check for resolution with follow-up angiogram in 3–5 min.
b
If the spasm does not resolve, one must consider the possibility of a dissection
or atheroembolism.
• Aggressive distal wire placement can lead to renal capsular perforation and
perirenal hematoma
b
Clue is significant flank pain during/after procedure.
b
CT may show perirenal/pararenal hemorrhage.
b
Treat conservatively – rarely requires embolotherapy.
• Renal atheroembolism
b
If possible, treat with suction thrombectomy using a microcatheter.
b
Consider infusion of thrombolytic agent such as Alteplase (Genetech, San
Francisco, CA). This is typically infused using a bolus of 4–8 mg over
5–10 min.
Alternative, use a short infusion of thrombolytic therapy for 4–8 h using
0.5–1.0 mg/h of Alteplase.
Key Points
• Select patients carefully for optimum outcomes
b
Renal artery intervention is good for patients with non-invasive imaging
exams positive for RAS and:
Severe, new, or worsening hypertension
Cardiac destabilization syndromes
152 S. Misra
b
Questionable indications for renal dysfunction
Little evidence exists to support stenting/angioplasty to improve
renal function except in patients with a single kidney and severe
RAS.
• Avoid renal artery dissection and rupture:
b
Carefully select renal artery and keep the guidewire in the lumen and
avoid wire prolapse.
b
Appropriately size the renal artery.
• Dilate/stent renal artery to 6 mm or more if at all possible.
b
Improved long-term results and less restenosis.
• FMD responds to angioplasty alone.
b
Stents used only for complicating dissection with limitation to forward
flow.
Suggested Reading
1. Baum SA and Pentecost MJ. Abrams’ Angiography Volume 3 1997.
2. Blum U, Krumme B, Flugel P, et al. Treatment of ostial renal-artery stenoses with vascular
endoprostheses after unsuccessful balloon angioplasty. N Engl J Med 1997; 336: 459–465.
3. Misra S, Gomes M, Matthews V, et al. Embolic protection devices in patients with renal artery
stenosis with chronic renal insufficiency: A clinical study. J Vasc Interv Radiol 2008 in press.
4. Misra S, Sturludottir M, Matthews V, et al. Treatment of Complex Stenoses Involving Renal
Artery Bifurcations using Drug-eluting Stents. J Vasc Interv Radiol 2008; 19(2): 272–278.
5. Misra S, Thatipelli MR, Howe PW, et al. Preliminary study of the use of drug-eluting stents in
atherosclerotic renal artery stenoses 4 mm in diameter or smaller. J Vasc Interv Radiol. 2008
Nov; 19(11): 1639–45. Epub 2008 Sep 12.
6. Radermacher J, Chavan A, Bleck J, et al. Use of Doppler ultrasonography to predict the
outcome of therapy for renal-artery stenosis. N Engl J Med 2001; 344: 410–417.
Angioplasty/Stenting of Mesenteric Arteries
Stefan Müller-Hülsbeck
Clinical Features
• Chronic mesenteric ischemia (CMI), first described as “abdominal angina” by
Goodman in 1918 and as a distinct entity by Dunphy in 1936, is a rare disorder.
• CMI is usually diagnosed late after the initial presentation usually after several
investigations have ruled out other causes of the patient’s symptoms.
• The number of arteries that must be involved before symptoms of ischemia occur
is still debated. Most agree that at least two of the celiac artery (CA), the supe-
rior mesenteric artery (SMA), or the inferior mesenteric artery (IMA) should be
stenosed or occluded for a diagnosis of CMI to be made. A stenosis or occlu-
sion of a single visceral vessel is usually asymptomatic because of preservation
of flow to the gastrointestinal tract via collateral vessels.
• CMI is caused by intermittent episodes of intestinal ischemia, usually associated
with the increased metabolic demand caused by digestion.
• Symptoms due to CMI include chronic postprandial pain, nausea, diarrhea, and
obvious weight loss. Patients often describe a “fear of food.”
• Atherosclerosis is the most common cause of CMI. Vasculitis and Takayasu
disease are other less likely causes of this condition.
Diagnostic Evaluation
Clinical
Clinical signs are uncommon.
• Abdominal bruit due to a stenosis is rare.
• Weight loss with no obvious cause.
• The most important factor in the diagnosis of CMI is a suspicion of the condition
in the presence of appropriate symptoms and no other obvious cause.
153
R.A. Morgan, E. Walser (eds.), Handbook of Angioplasty and Stenting Procedures,
Techniques in Interventional Radiology, DOI 10.1007/978-1-84800-399-6_13,
C
Springer-Verlag London Limited 2010
154 S. Müller-Hülsbeck
Laboratory
• There is no laboratory test for the diagnosis of CMI.
Imaging
• Non-invasive imaging has replaced angiography as the main initial imaging
method for the evaluation of patients with suspected CMI.
• Color duplex sonography (CDS) is effective for the detection of stenoses at the
origins of the visceral vessels.
b
A hemodynamically significant lesion is confirmed by Aliasing on color flow
Doppler ultrasound and a peak systolic velocity of >1.8 m/s.
• CTA and MRA are also effective for the diagnosis of occlusive disease at the
origins of the visceral vessels (Fig. 1).
• All three modalities are of variable accuracy in the diagnosis of more peripheral
stenoses or occlusions beyond the vessel origins.
• The aim of imaging is to
b
Assess the origins of the CA, the SMA, and the IMA.
b
Assess for the presence of a prominent collateral vessel such as the Arc of
Riolan or a prominent pancreaticoduodenal arcade.
a
b
Fig. 1 (a, b) Contrast-enhanced CT angiography. These maximum intensity projection (MIP)
images indicate calcified plaque close to the origin of a severely stenosed SMA in the coronal
and sagittal planes
Angioplasty/Stenting of Mesenteric Arteries 155
b
Demonstrate the exact location of any stenoses or occlusions.
b
Target subsequent treatment.
Indications
• Symptoms consistent with CMI, i.e., chronic postprandial pain, nausea, diarrhea,
and obvious weight loss.
• Diagnosis by imaging of stenoses or occlusions of two or more of the CA, SMA,
or IMA.
Contraindications
• Median Arcuate Ligament Syndrome (MALS)
b
This causes a functional stenosis of the CA, occurs in young patients and is
rare.
b
MALS may lead to considerable abdominal pain and weight loss.
b
Diagnosis is by color duplex sonography and/or CTA and/or MRA.
b
The condition may be difficult to distinguish from atherosclerotic disease.
The absence of atheroma elsewhere, the absence of calcification, symptoms
in a relatively young patient, and the characteristic imaging findings of the
ligament on CT or MR imaging are helpful indicators of the diagnosis.
b
The treatment of MALS is surgery, not angioplasty or stenting.
• Allergy to iodinated contrast medium is a relative contraindication. Although
angioplasty/stenting of the visceral vessels is very difficult if an alternative
contrast medium such as carbon dioxide is used.
Patient Preparation
• Standard sterile preparation as for other vascular interventions.
Relevant Anatomy
• Normal anatomy:
b
The SMA rises at the level of L1.
b
The origin of the IMA arises at the level of L3.
b
The origins of the SMA and the IMA are stable.
• Aberrant anatomy: The variable origin of the hepatic arteries is well known from
pathological and angiographic studies. These variants are not of concern for this
procedure.
156 S. Müller-Hülsbeck
• The common hepatic artery arising from the celiac artery is the most common
type found in 70% of subjects.
Equipment Required
• The equipment required is similar to other visceral vascular interventions.
• Cannulation of the CA, SMA, and IMA is usually achieved with a cobra catheter
or a reversed-curve catheter such as a sidewinder, a Sos Omni, or a Rim catheter.
• Either standard 0.035-inch or better smaller caliber 0.018-inch and 0.014-inch
systems can be used for PTA and stenting.
Pre-procedure Medications
• Most patients also have cardiovascular disease elsewhere, and are generally
already taking Aspirin +/− Statin medication.
• It is not a requirement of this procedure for patients to be on specific pre-
procedural medications.
Procedure
Arterial/Venous Access
• As usual, peripheral venous access is required for the administration of medica-
tions during the procedure.
• Procedures are performed usually from a femoral artery access, either the right
or the left.
• A standard 6F 10 cm sheath may be used. However, a longer sheath 35–45-cm
long is preferable, because it enables peri-procedural angiography through the
sheath with catheters, guidewires, or stent delivery systems in situ in the target
vessel.
• It may be problematic to pass catheters into vessels that curve inferiorly. In these
cases, a transbrachial access may be chosen, either initially after evaluation of
the vessel orientation from the imaging or if access into the target vessel from a
femoral access fails.
• In general, access is from the femoral artery in more than 90% of patients.
Angiography
• Flush aortography is usually performed before selective cannulation of the target
vessel to provide angiographic correlation of the pre-procedural imaging findings.
Angioplasty/Stenting of Mesenteric Arteries 157
• Angiography should be performed using an aortic flush catheter, a power injector,
and a standard volume and rate of injection suitable for aortography, e.g., 20 mL
of contrast medium at 10 mL/sec.
• Aortography should be performed in the anteroposterior and lateral projections
to identify the origins of the visceral vessels.
Intra-procedural Medications
• 5,000 units of intra-arterial heparin.
• 20-mg intravenous Buscopan – if there is significant image impairment because
of bowel movement.
Assessing the Lesion
• The vast majority of lesions are at the origins of the vessels. More distal stenoses
are unusual.
• The vast majority of stenoses can be traversed.
• Occlusions are very difficult to traverse. Most interventionalists would not
attempt to recanalize an occluded CA, SMA, or IMA.
• If more than one vessel is stenosed, the SMA or CA should be treated preferen-
tially to the IMA. The IMA is usually a small vessel and any benefit from treating
an IMA stenosis is generally less than revascularization of lesions involving the
CA or SMA.
Pressure Measurements
• Pressure measurements are usually not necessary and are only warranted in
lesions where there is uncertainty regarding whether the stenosis is significant
or not. A systolic pressure drop of more than 20 mmHg is an indication for
treatment.
Choosing a Balloon or a Stent
• Although there is no convincing evidence regarding angioplasty versus stenting,
most operators would select a stent for the treatment of an ostial stenosis or a
lesion within 10 mm of the vessel origin.
• For more distal lesions, PTA alone is usually performed.
158 S. Müller-Hülsbeck
Performing the Procedure
Crossing the Lesion
• A long sheath or guiding catheter is advanced into the upper abdominal aorta.
• The ostium of the vessel is cannulated with a cobra or a Sidewinder-shaped
catheter (if the approach is from the groin), or a multipurpose catheter (if a
transbrachial route has been used).
• With the catheter tip located close to the stenosis, the lesion is usually crossed
with a 0.035-inch hydrophilic guidewire. Some operators prefer to cross the
lesion with a smaller caliber guidewire, in which case a 0.018- or a 0.014-inch
guidewire, (either hydrophilic or with a hydrophilic tip) may be used.
• After the guidewire has traversed the lesion, the catheter is advanced across the
lesion followed by exchange of the hydrophilic guidewire for a stiffer guidewire
(0.035 or 0.018 inch). The Amplatz superstiff or Rosen guidewires are popular
guidewires for this purpose.
Deploying the Balloon or Stent
• Most interventionalists perform primary stenting.
b
For tight stenoses, predilation prior to stent insertion may be helpful to enable
the stent on its delivery catheter to be advanced across the lesion (e.g., 4 mm
balloon).
b
Either over the wire or rapid exchange (monorail) balloons may be used.
b
Predilation is advisable for very narrow, calcified stenoses.
• If PTA is the planned definitive therapy, the diameter of the balloon should be
chosen based on the size of the vessel to be stented.
b
This measurement can be obtained from previous CT images or using the
measuring facility on the angiographic equipment.
b
Although the diameters of the vessels vary widely from patient to patient,
suggested balloon diameters are as follows: Celiac trunk and SMA 6–7 mm;
IMA 4 mm.
• Inflation of the balloon using a manometer to limit excessive inflation pressures
may prevent the rare complication of vessel rupture.
• Self-expanding or balloon-expandable stents may be used. Short balloon-
expandable stents are most commonly used for ostial lesions, because of their
improved deployment accuracy in this type of location compared with self-
expanding stents.
• In general, balloon-expandable stents are used for ostial lesions. Self-expanding
stents are usually reserved more distal lesions, if PTA fails for these latter lesions.
Angioplasty/Stenting of Mesenteric Arteries 159
Self-expanding stents are also used occasionally for the treatment of dissection
involving the splanchnic vessels.
• Once the stent is in place, angiography is performed to confirm that the stent is
in the correct location prior to deployment. For ostial lesions, the stent should
protrude by 2–3 mm into the aorta.
• All PTA and stenting procedures should be performed in the appropriate projec-
tion at 90
◦
to the lesion, usually the full lateral position. If the proximal end of the
stent protrudes into the aorta, the proximal end may be flared by a larger balloon
after deployment.
Endpoint
• Completion angiography should indicate a fully expanded stent in the correct
location across the lesion.
• A widely patent vessel at completion angiography indicated success.
Examples of three cases are provided in Figs. 2, 3, and 4.
Immediate Post-procedure Care
• If possible, a closure device should be used.
• The arterial puncture site should be monitored in the standard manner.
Follow-Up and Post-procedure Medications
• There is no standard follow-up protocol.
• Color duplex sonography to confirm patency may be performed before discharge.
• Some operators administer intravenous heparin for 24 h or low-molecular heparin
until discharge.
• Low-dose aspirin is usually prescribed to be continued indefinitely.
• Most operators would also administer Clopidogrel 75 mg daily for 6 weeks
(Fig. 5).
Results
• The outcomes of endovascular therapy are very respectable and compare favor-
ably with surgery with mean primary patency rates of 76% at 15 months,
160 S. Müller-Hülsbeck
a
c
d
b
Fig. 2 (a) This angiogram, obtained in a lateral 90
◦
projection, shows a high-grade ostial
stenosis of the celiac trunk and a moderate stenosis of the SMA main trunk. (b) This image
shows a 6×18-mm stent deployed in celiac trunk, a 0.014-inch guidewire is still in place, and a
6F sheath is placed below the origin. (c) Shows a second stent, 6×18 mm, implanted in the SMA
during the same procedure. (d) Final angiography after completing the intervention shows a widely
patent celiac trunk and SMA with no residual stenosis