http://dqsendovascular.blogspot.kr/2012/10/evar-devices-summary.html
Endovascular aortic repair requires that specific anatomic criteria are fulfilled, and, for those with appropriate anatomy, this technique has become a preferred approach and allows the treatment of patients who might not otherwise be candidates for surgical aortic repair due to medical comorbidities. So It is still warrant sthat this procedurest is always an alternative way to manage AAA, not replacing the gold standart of open repair due to rate of complication which going to discussed elsewhere
Endovascular repair with abdominal stent-graft devices is primarily used to treat infrarenal abdominal aortic aneurysm with or without associated iliac artery aneurysm. Although not yet approved for clinical use in the United States, branched and fenestrated endovascular aortic devices have been developed to allow perfusion into specific aortic branches depending upon the level of repair (eg, renal artery, internal iliac artery). These advanced devices allow endovascular management of juxtarenal and potentially suprarenal aneurysms, and preservation of hypogastric flow when an adequate landing zone in the common iliac artery is not present.
The placement of aortic endovascular grafts is associated with device-related complications, which can include component disconnection, stent-graft buckling and migration over time. Secondary intervention is frequently needed [1-3]. As such, these devices require lifelong surveillance; the long-term outcomes for these devices continue to be studied.
The specific devices available for endovascular repair of the abdominal aorta will be reviewed here. The indications for, placement of, and complications of these devices are discussed elsewhere.
The aorta is the major arterial conduit conveying blood from the heart to the systemic circulation. It originates immediately beyond the aortic valve ascending initially, then curving to form the aortic arch, and finally descending caudally adjacent the spine. The descending thoracic aorta continues through the hiatus of the diaphragm to become the abdominal aorta which extends retroperitoneally to its bifurcation into the common iliac arteries at the level of the fourth lumbar vertebra. The abdominal aorta lies slightly left of the midline to accommodate the inferior vena cava which is in close apposition. The branches of the abdominal aorta (superior to inferior) include the left and right inferior phrenic arteries, left and right middle suprarenal arteries, the celiac axis, superior mesenteric artery, left and right renal arteries in addition to occasional accessory renal arteries, left and right gonadal arteries, inferior mesenteric artery, the paired lumbar arteries (L1-L4) and middle sacral artery. The abdominal aorta bifurcates into the left and right common iliac arteries, which most often arise at the level of the 4th lumbar vertebra. The common iliac artery bifurcates into the external iliac and internal iliac arteries at the pelvic inlet. The internal iliac artery has superior and inferior divisions that supply the pelvic viscera and muscles. The external iliac artery passes beneath the inguinal ligament to become the common femoral artery.
Endovascular aneurysm repair refers to the insertion of endovascular graft components ), usually via a femoral approach. The endovascular graft is constructed by the in vivo delivery and deployment of the device components in an established order determined by the specific anatomy of the patient. Upon deployment, the endograft expands, contacting the aortic wall proximally and aorta or iliac vessels distally, excluding the aneurysmal aortic wall from blood flow and pressure.
Although there are significant variations in endovascular graft design, three types of components are common to all: a delivery system, main body device, and device (limb) extensions.
Delivery system — The various endograft components are typically delivered through the femoral artery, either by direct surgical cutdown or percutaneously. If the femoral artery is too small to accommodate the delivery system, access can be obtained by suturing a synthetic graft of appropriate diameter (often 10 mm) to the common iliac artery to create an iliac conduit through a retroperitoneal incision. The size of the delivery system varies depending upon the device diameter required to provide proper endograft fixation.
Main device — The main body device for the abdominal aorta is usually bifurcated. Endovascular grafts rely primarily upon outward tension in the proximal graft to maintain the positioning of the graft. Fixation systems may also include barbs or a suprarenal uncovered extension. Bifurcated abdominal aortic grafts require adjunctive placement of iliac artery limbs to complete the graft. The iliac limbs on the main body device vary in length depending upon whether the graft is a two- or three-component graft. Two-component grafts have one short and one long iliac limb. Three-component devices have two short limbs.
Endovascular grafts for the abdominal aorta are generally bifurcated; however, some situations require the use of a unibody (ie, not bifurcated) graft, also known as an aorta-uni-iliac (AUI) device. These grafts are used in patients with severe unilateral iliac artery stenosis or occlusion. AUI devices can also be used for the treatment of some ruptured aneurysms. A bifurcated-to-unilateral graft conversion kit can be used in the situation when contralateral iliac artery access or contralateral gate cannulation is difficult or impossible. This kit effectively turns a bifurcated main body graft into a unilateral graft by covering one of the iliac limbs proximally. After deployment of an AUI device, a plug may be inserted into the contralateral iliac artery to prevent retrograde flow of blood into the aneurysm sac, if needed. The contralateral extremity typically requires a femoro-femoral crossover bypass for perfusion.
Extensions — One or more extension devices may be needed to provide a complete proximal or distal seal. Following the deployment of the main device and any necessary contralateral limbs or extensions, an aortogram is performed to assure that the endograft has completely excluded the aneurysm from the circulation. The term “endoleak” was coined to describe the persistence of blood flow into the aneurysm. If additional ballooning of the device does not firmly appose the graft to the aortic wall and eliminate a type I endoleak, placement of additional proximal aortic or iliac extensions may be needed.
Abdominal endovascular devices are increasingly being used as a minimally-invasive alternative to open surgical repair of the aorta. The main indication for these devices is treatment of abdominal aortic aneurysm. Endovascular repair of the abdominal aorta has also been used to treat isolated infrarenal aortic dissection, traumatic aortic injuries, and aortic atheroembolism . Endovascular grafts for the abdominal aorta are generally modular, bifurcated devices; however, an aorta-uni-iliac (AUI) device or bifurcated-to-unilateral graft conversion kit may be needed.Controlled comparisons of abdominal aortic stent-grafts have not been performed. Devices available to treat the abdominal aorta include the AneuRx®, Zenith®, Excluder®, AFX and Powerlink®, Talent®, and Endurant® grafts
Endovascular aortic repair requires that specific anatomic criteria are fulfilled, and, for those with appropriate anatomy, this technique has become a preferred approach and allows the treatment of patients who might not otherwise be candidates for surgical aortic repair due to medical comorbidities. So It is still warrant sthat this procedurest is always an alternative way to manage AAA, not replacing the gold standart of open repair due to rate of complication which going to discussed elsewhere
Endovascular repair with abdominal stent-graft devices is primarily used to treat infrarenal abdominal aortic aneurysm with or without associated iliac artery aneurysm. Although not yet approved for clinical use in the United States, branched and fenestrated endovascular aortic devices have been developed to allow perfusion into specific aortic branches depending upon the level of repair (eg, renal artery, internal iliac artery). These advanced devices allow endovascular management of juxtarenal and potentially suprarenal aneurysms, and preservation of hypogastric flow when an adequate landing zone in the common iliac artery is not present.
The placement of aortic endovascular grafts is associated with device-related complications, which can include component disconnection, stent-graft buckling and migration over time. Secondary intervention is frequently needed [1-3]. As such, these devices require lifelong surveillance; the long-term outcomes for these devices continue to be studied.
The specific devices available for endovascular repair of the abdominal aorta will be reviewed here. The indications for, placement of, and complications of these devices are discussed elsewhere.
The aorta is the major arterial conduit conveying blood from the heart to the systemic circulation. It originates immediately beyond the aortic valve ascending initially, then curving to form the aortic arch, and finally descending caudally adjacent the spine. The descending thoracic aorta continues through the hiatus of the diaphragm to become the abdominal aorta which extends retroperitoneally to its bifurcation into the common iliac arteries at the level of the fourth lumbar vertebra. The abdominal aorta lies slightly left of the midline to accommodate the inferior vena cava which is in close apposition. The branches of the abdominal aorta (superior to inferior) include the left and right inferior phrenic arteries, left and right middle suprarenal arteries, the celiac axis, superior mesenteric artery, left and right renal arteries in addition to occasional accessory renal arteries, left and right gonadal arteries, inferior mesenteric artery, the paired lumbar arteries (L1-L4) and middle sacral artery. The abdominal aorta bifurcates into the left and right common iliac arteries, which most often arise at the level of the 4th lumbar vertebra. The common iliac artery bifurcates into the external iliac and internal iliac arteries at the pelvic inlet. The internal iliac artery has superior and inferior divisions that supply the pelvic viscera and muscles. The external iliac artery passes beneath the inguinal ligament to become the common femoral artery.
Endovascular aneurysm repair refers to the insertion of endovascular graft components ), usually via a femoral approach. The endovascular graft is constructed by the in vivo delivery and deployment of the device components in an established order determined by the specific anatomy of the patient. Upon deployment, the endograft expands, contacting the aortic wall proximally and aorta or iliac vessels distally, excluding the aneurysmal aortic wall from blood flow and pressure.
Although there are significant variations in endovascular graft design, three types of components are common to all: a delivery system, main body device, and device (limb) extensions.
Delivery system — The various endograft components are typically delivered through the femoral artery, either by direct surgical cutdown or percutaneously. If the femoral artery is too small to accommodate the delivery system, access can be obtained by suturing a synthetic graft of appropriate diameter (often 10 mm) to the common iliac artery to create an iliac conduit through a retroperitoneal incision. The size of the delivery system varies depending upon the device diameter required to provide proper endograft fixation.
Main device — The main body device for the abdominal aorta is usually bifurcated. Endovascular grafts rely primarily upon outward tension in the proximal graft to maintain the positioning of the graft. Fixation systems may also include barbs or a suprarenal uncovered extension. Bifurcated abdominal aortic grafts require adjunctive placement of iliac artery limbs to complete the graft. The iliac limbs on the main body device vary in length depending upon whether the graft is a two- or three-component graft. Two-component grafts have one short and one long iliac limb. Three-component devices have two short limbs.
Endovascular grafts for the abdominal aorta are generally bifurcated; however, some situations require the use of a unibody (ie, not bifurcated) graft, also known as an aorta-uni-iliac (AUI) device. These grafts are used in patients with severe unilateral iliac artery stenosis or occlusion. AUI devices can also be used for the treatment of some ruptured aneurysms. A bifurcated-to-unilateral graft conversion kit can be used in the situation when contralateral iliac artery access or contralateral gate cannulation is difficult or impossible. This kit effectively turns a bifurcated main body graft into a unilateral graft by covering one of the iliac limbs proximally. After deployment of an AUI device, a plug may be inserted into the contralateral iliac artery to prevent retrograde flow of blood into the aneurysm sac, if needed. The contralateral extremity typically requires a femoro-femoral crossover bypass for perfusion.
Extensions — One or more extension devices may be needed to provide a complete proximal or distal seal. Following the deployment of the main device and any necessary contralateral limbs or extensions, an aortogram is performed to assure that the endograft has completely excluded the aneurysm from the circulation. The term “endoleak” was coined to describe the persistence of blood flow into the aneurysm. If additional ballooning of the device does not firmly appose the graft to the aortic wall and eliminate a type I endoleak, placement of additional proximal aortic or iliac extensions may be needed.
Abdominal endovascular devices are increasingly being used as a minimally-invasive alternative to open surgical repair of the aorta. The main indication for these devices is treatment of abdominal aortic aneurysm. Endovascular repair of the abdominal aorta has also been used to treat isolated infrarenal aortic dissection, traumatic aortic injuries, and aortic atheroembolism . Endovascular grafts for the abdominal aorta are generally modular, bifurcated devices; however, an aorta-uni-iliac (AUI) device or bifurcated-to-unilateral graft conversion kit may be needed.Controlled comparisons of abdominal aortic stent-grafts have not been performed. Devices available to treat the abdominal aorta include the AneuRx®, Zenith®, Excluder®, AFX and Powerlink®, Talent®, and Endurant® grafts
Characteristics of abdominal endovascular devices
| Endograft | Materials graft/support | Suprarenal fixation | Active proximal fixation/hooks | Native aortic neck diameter (range in mm) | Native iliac diameter (range in mm) | Maximum bifurcated main body device/introducer sheath diameter (French, OD*) | Potential advantages |
| AneuRx® (Medtronic) | Polyester/nitinol | No | No | 20 to 26 | 8 to 22 | 21 | Hydrophilic delivery system |
| Endurant® (Medtronic) | Polyester/ electropolished nitinol | Yes | Yes | 19 to 32 | 8 to 25 | 20 | Indications include short (10 mm) aortic neck, angulated neck |
| Powerlink® (Endologix) | PTFE/cobalt chromium alloy | Yes | No | 18 to 32 | 10 to 23 | 17 | Anatomic fixation at iliac bifurcation, low profile |
| Excluder® (Gore) | PTFE/nitinol | No | Yes | 19 to 29 | 10 to 18.5 | 20 | C3 delivery system, ability to recapture and reposition body, delivery sheath with hemostatic seal |
| Talent® (Medtronic) | Polyester/nitinol | Yes | No | 18 to 32 | 8 to 22 | 24 | Indication for short (10 mm) aortic neck, angulated necks |
| Zenith® (Cook Medical) | Polyester/stainless steel | Yes | Yes | 18 to 32 | 8 to 20 | 26 | Spiral Z flexible limbs |
PTFE: polytetrafluoroethylene.
* OD: outer diameter.
* OD: outer diameter.
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