26
length and 8 to 20 mm in diameter (measured outer wall to outer wall)
is required . These sizing measurements are critical to the performance of
the endovascular repair .
• Key anatomical elements that may affect successful exclusion of the
aneurysm include severe proximal neck angulation (>60 degrees for
infrarenal neck to axis of AAA or >45 degrees for suprarenal neck relative
to the immediate infrarenal neck); short proximal aortic neck (<15 mm);
an inverted funnel shape (greater than 10% increase in diameter over
15 mm of proximal aortic neck length); and circumferential thrombus
and/or calcification at the arterial implantation sites, specifically the
proximal aortic neck and distal iliac artery interface . In the presence
of anatomical limitations, a longer neck may be required to obtain
adequate sealing and fixation . Irregular calcification and/or plaque may
compromise the attachment and sealing at the fixation sites . Necks
exhibiting these key anatomical elements may be more conducive to
graft migration or endoleak .
• Adequate iliac or femoral access is required to introduce the device into
the vasculature . Access vessel diameter (measured inner wall to inner
wall) and morphology (minimal tortuosity, occlusive disease and/or
calcification) should be compatible with vascular access techniques and
delivery systems of the profile of a 16 French (6 .0 mm OD) or 17 French
(6 .5 mm OD) vascular introducer sheath . Vessels that are significantly
calcified, occlusive, tortuous or thrombus-lined may preclude placement
of the endovascular graft and/or may increase the risk of embolization,
graft kinking, or thromboses . A vascular conduit technique may be
necessary to achieve success in some patients .
• Pre-existing regions of stenosis/narrowing (less than approximately 20
mm ID in the aorta or 7 to 8 mm ID in the iliacs) have been shown to
increase the risk of a thromboembolic event (e .g ., graft limb occlusion) .
The potential for this increased risk in these patients may preclude
placement of an endovascular graft . Dilatation of these regions with
a noncompliant balloon and/or stent placement may be necessary
to help assure maintained graft patency and to reduce the risk of a
thromboembolic event . Additionally, the completion angiogram (with
stiff wire guides removed) should be reviewed carefully to determine
if further treatment in these regions is necessary (e .g ., adjunctive
ballooning or stenting) . Failure to remove the stiff wire guide prior to the
angiogram could mask any limb kinking or narrowing that might occur
when the wire guide is removed .
• Follow-up imaging should be carefully reviewed for narrowing within the
graft leg . Patients with a graft leg lumen of less than approximately 5 mm
ID may be at increased risk of a thromboembolic event (e .g ., graft limb
occlusion) . Reintervention (e .g ., noncompliant ballooning or stenting
in these regions) should be considered to help assure maintained graft
patency and to reduce the risk of a thromboembolic event .
• Patients with poor outflow or a hypercoagulable state (e.g., cancer) may
be at an increased risk of a thromboembolic event .
• The Zenith Alpha Abdominal Endovascular Graft is not recommended in
patients who cannot tolerate contrast agents necessary for intraoperative
and postoperative follow-up imaging . All patients should be monitored
closely and checked periodically for a change in the condition of their
disease and the integrity of the endoprosthesis .
• The Zenith Alpha Abdominal Endovascular Graft is not recommended
in patients exceeding weight and/or size limits which compromise or
prevent the necessary imaging requirements .
• Inability to maintain patency of at least one internal iliac artery or
occlusion of an indispensable inferior mesenteric artery may increase the
risk of pelvic/bowel ischemia .
• Multiple large, patent lumbar arteries, mural thrombus and a patent
inferior mesenteric artery may all predispose a patient to Type II
endoleaks . Patients with uncorrectable coagulopathy may also have an
increased risk of Type II endoleak or bleeding complications .
• The Zenith AAA family of grafts has not been formally tested in the
following patient populations:
• traumatic aortic injury
• leaking, pending rupture or ruptured aneurysms
• mycotic aneurysms
• pseudoaneurysms resulting from previous graft placement
• revision of previously placed endovascular grafts
• uncorrectable coagulopathy
• indispensable mesenteric artery
• genetic connective tissue disease (e.g., Marfans or Ehlers-Danlos
Syndromes)
• concomitant thoracic aortic or thoracoabdominal aneurysms
• patients with active systemic infections
• pregnant or nursing females
• patients less than 18 years of age
• mordibly obese patients
• patients with less than 15 mm in length or greater than 60 degrees
angulation of the proximal aortic neck relative to the long axis of the
aneurysm
• patients with two occluded internal iliac arteries
• Successful patient selection requires specific imaging and accurate
measurements; please see
Section 4 .3 Pre-Procedure Measurement
Techniques and Imaging .
• All lengths and diameters of the devices necessary to complete the
procedure should be available to the physician, especially when
preoperative case planning measurements (treatment diameters/
lengths) are not certain . This approach allows for greater intraoperative
flexibility to achieve optimal procedural outcomes .
4.3 Pre-Procedure Measurement Techniques and Imaging
• Lack of non-contrast CT imaging may result in failure to appreciate iliac
or aortic calcification, which may preclude access or reliable device
fixation and seal .
• Pre-procedure imaging reconstruction thicknesses >3 mm may result in
suboptimal device sizing, or in failure to appreciate focal stenoses from CT .
• Clinical experience indicates that contrast-enhanced spiral computed
tomographic angiography (CTA) with 3-D reconstruction is the strongly
recommended imaging modality to accurately assess patient anatomy
prior to treatment with the Zenith Alpha Abdominal Endovascular Graft .
If contrast-enhanced spiral CTA with 3-D reconstruction is not available,
the patient should be referred to a facility with these capabilities .
• Clinicians recommend positioning the x-ray C-arm during procedural
angiography such that the origins of the renal arteries, and particularly
the lowest patent renal artery, are well demonstrated prior to
deployment of the proximal edge of the graft material (sealing stent) of
the main body . Additionally, angiography should demonstrate the iliac
artery bifurcations such that the distal common iliacs are well defined
relative to the origin of the internal iliac arteries bilaterally, prior to
deployment of the iliac leg components .
Diameters
Utilizing CT, diameter measurements should be determined from the outer
wall to outer wall vessel diameter (not lumen measurement) to help with
proper device sizing and device selection . The contrast-enhanced spiral CT
scan must start 1 cm superior to the celiac axis and continue through the
femoral heads at an axial thickness slice of 3 mm or less .
Lengths
Utilizing CT, length measurements should be determined to accurately
assess infrarenal proximal neck length as well as planning main body sizes
and leg components for the Zenith Alpha Abdominal Endovascular Graft .
These reconstructions should be performed in sagittal, coronal , and 3-D .
•
The long-term performance of this endovascular graft has not yet
been established . All patients should be advised that endovascular
treatment requires lifelong, regular follow-up to assess their health
and the performance of their endovascular graft .
Patients with
specific clinical findings (e .g ., endoleaks, enlarging aneurysm or changes
in the structure or position of the endovascular graft) should receive
enhanced follow-up . Specific follow-up guidelines are described in
Section 11, IMAGING GUIDELINES AND POSTOPERATIVE FOLLOW-UP .
• The Zenith Alpha Abdominal Endovascular Graft is not recommended
in patients unable to undergo, or who will not be compliant with, the
necessary preoperative and postoperative imaging and implantation
studies as described in
Section 11, IMAGING GUIDELINES AND
POSTOPERATIVE FOLLOW-UP .
• After endovascular graft placement, patients should be regularly
monitored for perigraft flow, aneurysm growth or changes in the
structure or position of the endovascular graft . At a minimum, annual
imaging is required, including: 1) abdominal radiographs to examine
device integrity (separation between components, stent fracture or barb
separation) and 2) contrast and non-contrast CT to examine aneurysm
changes, perigraft flow, patency, tortuosity and progressive disease . If
renal complications or other factors preclude the use of image contrast
media, abdominal radiographs and duplex ultrasound may provide
similar information .
4.4 Device Selection
Strict adherence to the Zenith Alpha Abdominal Endovascular Graft IFU
sizing guide is strongly recommended when selecting the appropriate
device size
(Tables 9 .5 .1
thru
9 .5 .4)
. Appropriate device oversizing has
been incorporated into the IFU sizing guide . Sizing outside of this range can
result in endoleak, fracture, migration, device infolding or compression .
4.5 Implant Procedure
(Refer to
Section 10, DIRECTIONS FOR USE
)
• Appropriate procedural imaging is required to successfully position
the Zenith Alpha Abdominal Endovascular Graft and assure accurate
apposition to the aortic wall .
• Do not bend or kink the delivery system. Doing so may cause damage to
the delivery system and the Zenith Alpha Abdominal Endovascular Graft .
• To avoid any twist in the endovascular graft, during any rotation of the
delivery system, be careful to rotate all of the components of the system
together (from outer sheath to inner cannula) .
• To avoid damage to the sheath, be careful to advance all components of
the system together (from outer sheath to inner cannula) .
• Do not continue advancing any portion of the delivery system if
resistance is felt during advancement of the wire guide or delivery
system. Stop and assess the cause of resistance; vessel, catheter or
graft damage may occur . Exercise particular care in areas of stenosis,
intravascular thrombosis or in calcified or tortuous vessels .
• Inadvertent partial deployment or migration of the endoprosthesis may
require surgical removal .
• Unless medically indicated, do not deploy the Zenith Alpha Abdominal
Endovascular Graft in a location that will occlude arteries necessary to
supply blood flow to organs or extremities . Do not cover significant renal
or mesenteric arteries (exception is the inferior mesenteric artery) with
the endoprosthesis . Vessel occlusion may occur .
• Do not attempt to re-sheath the graft after partial or complete
deployment .
• Repositioning the stent graft distally after partial deployment of the
covered proximal stent may result in damage to the stent graft and/or
vessel injury .
• Inaccurate placement and/or incomplete sealing of the Zenith Alpha
Abdominal Endovascular Graft within the vessel may result in increased
risk of endoleak, migration or inadvertent occlusion of the renal or
internal iliac arteries . Renal artery patency must be maintained to
prevent/reduce the risk of renal failure and subsequent complications .
• Inadequate fixation of the Zenith Alpha Abdominal Endovascular Graft
may result in increased risk of migration of the stent graft . Incorrect
deployment or migration of the endoprosthesis may require surgical
intervention .
• Inadequate overlap of the Zenith Alpha Spiral-Z Endovascular Leg may
result in increased risk of migration of the stent graft and subsequent
endoleak .
• Systemic anticoagulation should be used during the implantation
procedure based on hospital- and physician-preferred protocol . If
heparin is contraindicated, an alternative anticoagulant should be
considered .
• To activate the hydrophilic coating on the outside of the Flexor
introducer sheath, the surface must be wiped with sterile gauze pads
soaked in saline solution . Always keep the sheath hydrated for optimal
performance .
• Minimize handling of the constrained endoprosthesis during preparation
and insertion to decrease the risk of endoprosthesis contamination and
infection .
• Maintain wire guide position during delivery system insertion.
• Fluoroscopy should be used during introduction and deployment to
