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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3955_Библиотеки_им_академика_М_И_Перельмана.pdf
Stent-Grafting of the Thoracic Aorta 221
Dissection and Acute Aortic Syndrome
• For acute type B dissections, the results of TEVR are better than surgery.
• Most series report mortality rates below 10% with paraplegia rates of less
than 3%.
• Most vascular centers would now regard endovascular therapy to be the first-line
treatment for acute complicated type B dissections.
• Indications for repair of chronic dissections have usually been limited to the onset
of complications and an aortic diameter exceeding 5.5–6.0 cm.
• The availability of data regarding the outcomes of EVR for chronic dissections is
very poor. In the series to date, the mortality rates have been acceptable but the
long-term success in preventing aortic expansion is unclear.
Traumatic Aortic Injury
• Although TEVR seems to have become the gold standard for TAI, there are rel-
atively limited data on outcomes. However, the procedural mortality is less than
10% throughout and the reported risk of paraplegia is negligible
• However, there remain concerns with the poor suitability and durability of the
available devices for this predominantly young population.
Complications
Stent Related
Maldeployment
• Failure to land the endograft in the correct location usually requires placement of
an additional device, either an additional endograft or a cuff. A supply of these
should be available for use if required to prevent procedural failure.
• Maldeployment is avoided by
b
Avoid hurrying during deployment
b
Perform check angiograms during deployment
b
Perform check angiograms in the appropriate obliquity
Endoleak
Similar to abdominal EVAR, these may be type 1, 2, or 3. Type 1 is the most frequent
followed by type 3 and finally type 2.
• Endoleaks are avoided by
b
Accurate pre-procedural planning and correct device selection
b
Accurate deployment of the endografts
222 J.-P. Beregi and M. Midulla
• Type 1 and type 3 endoleaks generally require treatment.
• Treatment of endoleaks may involve repeat balloon dilatation. However, insertion
of additional endografts is usually required.
• Type 2 leaks may be due to retrograde filling from the left subclavian artery if this
artery has been covered without bypass, or bypassed but not tied off at its origin.
Embolization of type 2 leaks from the left subclavian artery is usually performed,
if necessary, using Amplatz plugs or coils.
Related to Vascular Access
This may consist of iliac artery rupture because of trauma caused by the large
endograft delivery system.
• This is best treated by insertion of a covered stent. A supply of these should
always be kept in stock.
General Complications
• Stroke
b
Increased by excessive manipulations in the aortic arch
b
Increased by covering the left subclavian artery without bypass
b
Increased in the presence of atheroma in the aortic arch
• Paraplegia
b
Increased by endografting long lengths of aorta
b
Increased by previous abdominal aortic repair
b
Treat by spinal drainage
• Fever: It may occur as a result of thrombosis of aneurysmal sac or the false
lumen.
Key Points
• TEVAR should be considered for the treatment of aortic pathology involv-
ing the descending thoracic aorta.
• The diameter threshold for intervention on the descending aorta is 5.5 cm.
• In most cases, insertion of these devices is straightforward and does not
involve a long procedure time.
• A femoral arteriotomy is usually required, although percutaneous insertion
using closure devices is feasible.
• The technical success rates are very high and approach 100% in most series.
• The conversion rate to open surgery is negligible.
Stent-Grafting of the Thoracic Aorta 223
• The paraplegia rate is around 2% and the stroke rate is approximately 4%
in most series.
• The most common complication is a type 1 endoleak. This requires
reintervention and usually involves the insertion of additional endografts.
• The technique is relatively new and follow-up by imaging should be
lifelong.
Suggested Reading
1. Rousseau H, Verhoye JP, Heautot JF eds. Thoracic Aortic Diseases. Springer-Verlag,
Heidelberg, Berlin, 2006.
A recent comprehensive text book collecting the experiences of the worldwide best known
people who devoted their activity to thoracic aortic issues
2. Vilacosta I, Román JA. Acute aortic syndrome. Heart. 2001 Apr; 85(4):365–8. No abstract
available.
The introduction of the term “Acute Aortic Syndromes” with the description of the relative
anatomo-pathological entities
3. Gaxotte V, Thony F, Rousseau H, Lions C, Otal P, Willoteaux S, Rodiere M, Negaiwi Z, Joffre
F, Beregi JP. Midterm results of aortic diameter outcomes after thoracic stent-graft implantation
for aortic dissection: a multicenter study. J Endovasc Ther 2006 Apr; 13(2):127–38.
4. www.ctsnet.org
A thematic e-site dedicated to the cardiothoracic surgery with on-line books available for
consultations
Elective Endovascular Aneurysm Repair
(EVAR) of Abdominal Aortic Aneurysms (AAA)
Johannes Lammer and Maria Schoder
Clinical Features
• The incidence of AAA is 4% in the adult population and 11% in males older than
65 years.
• Men are 4–8 times more affected by AAA than women.
• Between 1993 and 2003 the overall rates of treated unruptured and rup-
tured AAAs in the US remained stable (unruptured 12–15/100,000; ruptured
1–3/100,000).
• Aneurysms should be treated when they are 5.5 cm or larger, symptomatic or
increase in size by 5 mm per year.
Diagnostic Evaluation
Clinical
• May present with a palpable non-tender abdominal mass.
• May present with a palpable tender abdominal mass.
• May present with abdominal or back pain.
• May present with symptoms related to distal embolization.
• May present with pain and hypotension because of rupture.
Ultrasound
• Ultrasonography is the basic tool for the diagnosis of AAA.
• Ultrasound is used for the screening of patients at risk for AAA.
CT Angiography (CTA)
• The main method used for the assessment of patients with a known AAA.
• CTA protocol (e.g., 64 row multislice CT).
225
R.A. Morgan, E. Walser (eds.), Handbook of Angioplasty and Stenting Procedures,
Techniques in Interventional Radiology, DOI 10.1007/978-1-84800-399-6_18,
C
Springer-Verlag London Limited 2010
226 J. Lammer and M. Schoder
b
Coverage from the superior mesenteric artery to the groin.
b
80–100 cc contrast medium (300–400 mg J/mL).
b
160–300 mAs, 120 kV, 64 × 0.625 mm, 0.75 sec rotation, pitch 1.2, trigger
level 150 HU, 8-sec delay post trigger.
b
Cross-sectional image reconstruction – 3 mm slice, reconstruction index (RI)
2 mm, soft kernel, W 900/C 250.
b
3D reconstruction − 1 mm slice, RI 0.5 mm, soft kernel (B-filter), W 900/ C
250, thin maximum intensity projection (MIP), MIP every 15
◦
in z-axis.
Contrast-Enhanced Magnetic Resonance Angiography (MRA)
• Less commonly used than CT.
• Useful for patients with abnormal renal function or allergy to iodinated contrast
medium.
• Protocol: Localizer, T1 weighted FFE axial, T2 weighted GRE axial, bolus
tracking.
• Contrast medium: 0.2 mmol/kg body weight, Gd-chelate (Omniscan, Dotarem,
Gadovist, MultiHance), saline solution flush, contrast-enhanced 3D-GRE (TFE,
FLASH) coronal, short TR (<3 ms), small flip angle (<30
◦
).
• 3D reconstruction – MIP every 15
◦
in z-axis.
Catheter Angiography
• Has largely been replaced by CTA and MRA.
• Used mainly as a problem solver:
b
To assess borderline neck.
b
To assess borderline iliac arteries.
• Method:
b
Performed with a calibrated flush catheter (pigtail, straight) with 1-cm lead
markers.
b
20–35cc contrast medium (300 mg J/mL).
b
Injected at 10–15 cc/sec.
b
Image abdominal aorta and pelvic arteries, oblique views if required.
Information Required from Imaging Studies
• Superior mesenteric artery (SMA) – this must be patent because the inferior
mesenteric artery (IMA) will be occluded after endograft placement.
• Renal arteries and accessory renal arteries.
EVAR of Abdominal Aortic Aneurysms 227
• Length, diameter, kinking, thrombus, and calcification of the aneurysm neck
(aorta between the renal arteries and the AAA), which forms the proximal landing
zone for the endograft.
• Length, diameter, kinking, thrombus, and calcification of the iliac arteries (which
form the distal landing zone and the access arteries).
• Diameter and calcification of the common femoral artery.
Indications for EVAR
• AAA with a diameter of 5.5 cm or larger.
• Symptomatic aneurysms (pain, tenderness, distal embolization). These should be
treated even if they are smaller than 5.5 cm diameter.
• Documented growth of more than 0.5 cm per year.
Contraindications
Because EVAR can be performed under local and spinal anesthesia, anatomic
factors are the dominant contraindications:
• Short infrarenal neck <10–15 mm.
• Wide infrarenal neck – >33 mm.
• Excessive neck angulation >65
◦
.
• Excessive thrombus or calcification in the neck is relative contraindication.
• A very conical neck.
• Small access vessels – <7 mm.
• Excessive iliac artery tortuosity and calcification.
Patient Preparation
• Chest X-ray.
• ECG.
• In symptomatic patients, exercise ECG, Thallium scanning, coronary CTA, or
cardiac MRI may be required.
• Laboratory parameters:
b
Coagulation tests.
b
Renal and liver function tests.
b
Blood cell count, hematocrit.
b
Cross-match four units of blood.
• Informed consent.
• Urinary catheter.
228 J. Lammer and M. Schoder
Relevant Anatomy
• There should be proximal and distal landing (or sealing) zones of adequate
dimension.
• With increasing experience, the absolute values of diameter, length, and angula-
tion may change.
• Standard inclusion criteria for EVAR:
b
Neck diameter 33 mm or less.
b
Neck length 15 mm or longer.
b
Angulation of <65
◦
.
b
Thrombus and severe calcification <50% circumference of neck.
b
CIA diameter 22 mm or less.
b
CIA length >35 mm.
b
Absence of excessive tortuosity and calcification.
b
The access vessels, i.e., femoral and external iliac arteries should be of
adequate caliber to accept the endograft delivery system, i.e., >7 mm diameter.
Equipment Required for EVAR
Stent-Grafts
• Types – Bifurcated, Aortouniiliac, or fenestrated:
b
Bifurcated – the most common type used for the majority of patients with
standard anatomy.
b
Aortouniiliac devices – used in patients with unilateral iliac artery disease or
in emergency aneurysm repair.
b
Fenestrated – used in patients with aneurysms unsuitable for conventional
stent-grafts (usually short and/or angulated necks).
• Examples of devices – Zenith (W. Cook, Europe), Endurant, Talent (Medtronic,
Santa Rosa, CA), Excluder (W. Gore, Flagstaff, AZ).
• Stent structure – stainless steel or nitinol.
• Graft fabric – polyester or ePTFE.
• Proximal fixation – infrarenal with hooks, suprarenal with or without hooks.
• Bifurcated design – modular or unibody.
• Delivery system 18–22F.
Catheters
• Pigtail catheter for aortography.
• A selection of selective catheters for manipulations in the iliac arteries and aorta,
and for cannulation of the contralateral limb:
EVAR of Abdominal Aortic Aneurysms 229
b
Cobra.
b
Multipurpose.
b
Vertebral or Berenstein.
b
Simmons 1 or Sos Omni catheters.
• Balloon catheters:
b
Compliant balloon up to 36 mm in diameter for balloon molding the attach-
ment sites, and anastomoses between the components.
b
Angioplasty balloon for dilating iliac stenoses.
Guidewires
• Standard guidewires.
• Exchange length very stiff guidewires to support the endograft delivery system:
b
Lunderquist (W. Cook).
b
Meier (Boston Scientific Corp.).
• Hydrophilic guidewires.
Additional Tools
• Introducer sheaths of different sizes − 6–18F.
• Palmaz stent – in case of a proximal type Ia endoleak.
• Self-expanding stents – in case of stenosis or kinking of stentgraft limbs.
• Wire loop snare – to aid retrograde cannulation of the contralateral limb if the
ipsilateral route is unsuccessful.
• Closure device if a surgical femoral arteriotomy is not used.
Technique of EVAR
Anesthesia
• The procedure is usually performed under general anesthesia.
• Spinal and local anesthesia are also options.
Arterial Access
Femoral access:
• Unilateral or bilateral surgical femoral arteriotomy
• Percutaneous femoral artery access using closure devices
230 J. Lammer and M. Schoder
• Conduit to the common iliac artery:
b
Used if the patient has small, narrowed, or even occluded external iliac
arteries, which are unsuitable for passage of the large stent-graft delivery
system.
b
A vascular surgeon sutures a bypass graft to the common iliac artery.
b
The stent-graft can be inserted through the bypass graft. At the end of the
procedure, either the bypass can be closed or it can be used as an iliofemoral
graft.
Intra-procedural Medications
These are administered before insertion of the stent-graft:
• Heparin 5000 IU.
• Broad spectrum antibiotics.
Procedure
Before Stent-Graft Deployment
• The contralateral femoral artery is catheterized and a 6F sheath is inserted.
• A diagnostic pigtail catheter is inserted via this access into the aorta to the level
of T12/L1.
• The ipsilateral femoral artery is catheterized.
• A standard guidewire and selective catheter (e.g., cobra) are advanced into the
upper thoracic aorta.
• The standard guidewire is exchanged for a very stiff guidewire (260-cm long
Lunderquist), which is placed with the tip in the ascending aorta.
• The stent-graft is inserted under fluoroscopic guidance.
• Care should be taken if there is resistance during passage of the stent-graft
through the iliac arteries to avoid dissections or rupture.
• The stent-graft should be advanced to the level of L1.
Deployment of the Stent-Graft
• Catheter angiography is performed to define the level of the renal arteries
(Fig. 1a):
• The stent-graft is deployed so that the graft material is located immediately below
the renal arteries.
• After deployment of the main body of the device, the pigtail catheter is withdrawn
over a standard guidewire.
• The contralateral limb is cannulated from the contralateral groin with a selective
catheter and a hydrophilic guidewire.
EVAR of Abdominal Aortic Aneurysms 231
a
b
Fig. 1 (a) Angiogram of
AAA before EVAR.
(b) Angiogram after
stentgraft placement
• After cannulation of the contralateral limb opening, the position of the guidewire
within, rather than without, the body of the graft should be confirmed either by
the i njection of contrast through a catheter, or by the rotation of a pigtail catheter.
• If retrograde cannulation of the limb is difficult, contralateral limb cannulation
can be achieved using a cross-over technique:
b
A sidewinder (Simmons 1) or Sos Omni catheter is placed across the flow
divider of the stent-graft main body.
b
A hydrophilic guidewire (curved, 260 cm) is advanced to the contralateral iliac
artery and snared.
• After inserting a second Lunderquist guidewire through the contralateral limb
opening into the aorta above the stent-graft, the contralateral limb is inserted.
• Balloon angioplasty should be performed at the proximal landing zone, the distal
landing zone and at the device connections to enhance the seal.
• If there is an aneurysmal common iliac artery (>23 mm diameter) as well as an
aortic aneurysm, it will be necessary to land the endograft limb in the external
iliac artery.
• Before this is performed, it is necessary to embolize the internal iliac artery
before insertion of the stent-graft to prevent retrograde flow into the aneurysmal
common iliac artery and aortic aneurysm sac.
• This is achieved by coils or an Amplatzer plug usually before the procedure.
Endpoint
• This is decided by good quality catheter angiography.
• The procedure is completed when angiography shows a patent stent-graft, patent
endograft limbs, and absence of flow into the aneurysm sac (endoleak) (Fig. 1b).