Pararenal aortic aneurysm repair using fenestrated endografts.

OBJECTIVE: We performed a systematic review of the current literature to analyze the immediate and follow-up results of fenestrated endovascular aortic aneurysm repair (F-EVAR) in patients with pararenal abdominal aortic aneurysms (AAAs). METHODS: The Medline, Embase, and Cochrane databases were searched to identify all studies reporting F-EVAR of pararenal AAAs published between January 2000 and May 2011. Two independent observers selected studies for inclusion, assessed the quality of the included studies, and performed the data extraction. Studies were selected based on specific predefined criteria. Outcomes were technical success (successfully completed procedure with endograft patency, preservation of target vessels, and no evidence of type I or III endoleak at postprocedural imaging), 30-day mortality, all-cause mortality, branch vessel patency, renal impairment, and secondary interventions. Between-study heterogeneity was calculated using I(2) statistics. Pooled estimates were calculated using a fixed-effects (I(2) <25%) or a random-effects (I(2) >25% to <50%) model. RESULTS: Nine studies were included reporting 629 patients who underwent F-EVAR for a pararenal AAA, of which 1622 target vessels were incorporated in an endograft design. Between-study heterogeneity was ≤ 41% for all outcomes. The pooled estimate (95% confidence interval [CI] was 90.4% (87.7%-92.5%) for technical success, 2.1% (1.2%-3.7%) for 30-day mortality, and 16% (12.5%-20.4%) for all-cause mortality. Follow-up was 15 to 25 months. The pooled estimate (95% CI) during follow-up was 93.2% (90.4%-95.3%) for branch vessel patency, 22.2% (16%-30.1%) for renal impairment, and 17.8% (13.5%-22.6%) for secondary interventions. CONCLUSIONS: Promising immediate and midterm results (up to 2 years) support F-EVAR as a feasible, safe, and effective treatment in a relatively high-risk cohort of patients with pararenal AAAs.

Direct videoscopic approach to the thoracic aorta for aortic endograft delivery: evaluation in a human cadaver circulation model.

PURPOSE: To examine the feasibility of a direct videoscopic approach to the descending thoracic aorta for branched endograft delivery to the aortic arch and abdominal aorta. METHODS: Aneurysms were created in the aortic arch and pararenal aorta of 3 human cadavers, and pulsatile flow was established using a roller pump. Thoracoscopically, 2 double-felted purse-string sutures were placed on the thoracic aorta. Via the most distal trocar, an endoscopic needle was used to insert a stiff guidewire into the aorta through the center of the purse-string suture. Under direct videoscopic control, a 20-F sheath was advanced over the wire into the aorta. Switching to fluoroscopic control, a fenestrated endograft was deployed in the aortic arch followed by placement of a branch graft into the left subclavian artery. The delivery sheath was withdrawn from the aorta while simultaneously tightening the purse-string sutures. A similar procedure was performed in the same cadaver for antegrade branched endograft delivery to the pararenal aorta. Correct deployment of the branched endografts was evaluated by post implant angiography and autopsy. RESULTS: The procedure was successfully completed in all cadavers. "Hemostasis" was obtained in all cadavers without aortic cross clamping. Median fluid loss was 165 mL. Autopsy proved all purse-string sutures to be adequately placed and all branched endografts to be deployed in the correct position. CONCLUSION: A direct videoscopic approach to the descending thoracic aorta proved a feasible technique for branched endograft delivery to the aortic arch and abdominal aorta in a human cadaver model.

Modular branched endograft system for aortic aneurysm repair: evaluation in a human cadaver circulation model.

A circulation model was created in 6 nonaneurysmal human cadavers to evaluate the deliverability, deployment, and acute performance of a modular branched endograft system for treatment of aortic aneurysms containing essential branch vessels. Two fenestrations were created in an appropriately sized aortic main endograft. Under fluoroscopic guidance, the main endograft was advanced to the target site and the fenestrations were aligned with the ostia of the renal arteries. Branch grafts were placed through the fenestrations into the renal arteries. The outcome was evaluated by post implant angiography and autopsy. Eleven branch grafts were deployed at the target site. All targeted renal arteries showed good patency. At autopsy, all main endografts were adequately deployed, and 10 of 11 branch grafts were locked in place. In this model, deliverability and deployment of the modular branch graft system is feasible in a reliable, predictable, and timely fashion.

Endoscopic type 2 endoleak repair following endovascular aortic aneurysm repair: acute results and follow-up experience.

The purpose of this study was to evaluate immediate and long-term results of endoscopic type 2 endoleak repair (EER) following endovascular abdominal aortic aneurysm repair. The basic methods include a retrospective review of electronic and paper medical records of patients admitted or referred to our institution for EER. Between July 1999 and October 2007, eight consecutive patients underwent EER. Mean operative time was 190 (104-355) min. One patient died preoperatively, due to profuse venous bleeding . One procedure was redone due to a missed pair of lumbar arteries. Mean hospital stay was five days (2-10). During mean follow-up, 50 months (29-91), one patient required additional coil embolization for a persistent type 2 endoleak. Four patients were diagnosed with a type 1 and one with a type 3 endoleak; three of these patients required an additional procedure. In conclusion, in this small series EER proved not to be beneficial.

Carotid artery dynamics after carotid angioplasty and stenting.

Carotid angioplasty and stenting (CAS) has emerged as an alternative treatment for carotid artery occlusive disease. As initial results in patients with an increased surgical risk appeared promising, the popularity of CAS has increased substantially over the last years and CAS has more often been advocated as an alternative to the gold standard, carotid endarterectomy (CEA). Several controlled trials comparing CAS with CEA are currently being conducted. However, long-term results of CAS are still sparse and several issues regarding the inherent differences between treatment modalities have not yet been elucidated. Interestingly, to date, very little attention has been directed towards the mobile features of the carotid artery and the implications of stent placement on carotid artery dynamics.

Direct videoscopic approach to the descending thoracic aorta for aortic arch endograft delivery: evaluation in a porcine model.

PURPOSE: To examine the feasibility of a direct videoscopic approach to the descending thoracic aorta for endograft delivery to the aortic arch. METHODS: A double purse-string suture was placed on the aorta of 3 pigs via a thoracoscopic approach. Subsequently, the aorta was cannulated in the center of the purse-string. A 22-F delivery catheter was advanced under fluoroscopic control over a guidewire via a trocar into the proximal aorta. After deployment of a tubular endograft, the catheter was withdrawn from the aorta while simultaneously tightening the purse-string suture, without aortic cross clamping. The outcome was evaluated by post implant angiography and autopsy results. RESULTS: The procedure was successfully completed in all animals, with a mean total procedure time of 126 minutes (range 118-137). Mean endograft implantation time from needle puncture to catheter extraction was 27 minutes (range 21-37). Hemostasis was obtained in all animals after withdrawal of the delivery catheter and tightening the purse-string suture. The mean blood loss was 143 mL (range 80-220). Autopsy proved all purse-string sutures to be adequately placed and all endografts deployed in the correct position. CONCLUSION: A direct videoscopic approach to the descending thoracic aorta proved a feasible technique for endograft delivery to the aortic arch in a porcine model.

Fenestrated and branched endografts: assessment of proximal aortic neck fixation.

PURPOSE: To investigate proximal fixation characteristics of different aortic endograft designs: a suprarenally placed fenestrated endograft, a modular branched endograft, an infrarenal endograft with suprarenal bare stent fixation, and the gold standard, a conventional hand-sewn anastomosis. METHODS: Ten human cadaveric aortas were obtained at autopsy and transected 20 mm below the renal arteries to mimic an infrarenal aneurysm neck. In random order, the infrarenal, fenestrated, and branched endografts were deployed into the aorta. Using a hydraulic material testing machine, longitudinal load was applied to the distal end of each endograft until migration occurred, thus defining the displacement force (DF). Subsequently, a hand-sewn infrarenal anastomosis was tested in a similar manner. RESULTS: The median DF was 4.67 N (3.82-6.37) for the infrarenal endograft, 9.17 N (8.03- 10.81) for the fenestrated endograft, and 16.95 N (14.78-19.67) for the branched endograft. The differences in DF between the infrarenal and fenestrated endografts and between the fenestrated and branched designs were statistically significant (both p=0.005). The median force to dislodge the graft from the conventional anastomosis was 89.16 N (71.24-105.23). CONCLUSIONS: Suprarenally placed endografts, especially with additional branch grafts, provide improved proximal fixation compared to an infrarenal endograft with suprarenal bare stent fixation. However, none of the tested endografts approached the optimal, time-proven fixation, the hand-sewn anastomosis.

A temporary hemostatic valve in the short limb of a bifurcated stent-graft to facilitate endovascular repair of ruptured aortic aneurysm: experimental findings.

PURPOSE: To evaluate a homemade tricuspid valve placed in the short limb of a bifurcated aortic stent-graft to facilitate endovascular treatment of ruptured abdominal aortic aneurysms (AAA). METHODS: A valve consisting of 3 polytetrafluoroethylene cusps was constructed in the short limb of a bifurcated stent-graft. The endoprosthesis was placed into an in vitro circulation model with pulsatile flow. Angiography was performed before and after insertion of the second graft limb. RESULTS: Angiographically, there was complete occlusion of the short limb before and normal patency after deployment of the second graft limb. Cannulation of the short limb with a guidewire was performed without technical difficulty. CONCLUSIONS: Addition of a temporary hemostatic valve in the short limb of a bifurcated stent-graft can potentially reduce blood loss during endovascular treatment of ruptured AAAs.

Impact of head movements on morphology and flow in the internal carotid artery after carotid angioplasty and stenting versus endarterectomy.

OBJECTIVE: Because stents can cause vessel angulation during movement, we hypothesized that internal carotid artery (ICA) stents might lead to alterations of cerebropetal blood flow. This study assessed three-dimensional anatomy and volumetric flow rate (VFR) in the ICA in various head positions by comparing patients treated with carotid angioplasty and stenting (CAS) with patients treated with carotid endarterectomy (CEA). METHODS: Three-dimensional time-of-flight magnetic resonance angiography and magnetic resonance flow quantification were performed on six subjects after CAS (median age, 70 years) and on six subjects after CEA (median age, 67 years). All investigations were performed in five head positions: neutral, bent forward, bent backward, and turned to the treated, ipsilateral side and to the contralateral side. Maximum-intensity projection reconstructions were obtained to measure maximal angulation of the ICA in the forward, backward, ipsilateral, and contralateral positions compared with neutral. Subsequently, the plane perpendicular to the ICA, 1 cm distal to the stent or 4 cm distal to the carotid bifurcation (CEA patients), was established. The VFR through this plane was measured for each position, and the forward, backward, ipsilateral, and contralateral positions were compared with neutral. RESULTS: In CAS patients, there was a median change in ICA angulation of +10.2 degrees (interquartile range, +7.3 degrees to +17.9 degrees ) in the forward position, compared with +0.2 degrees (-1.0 degrees to +2.4 degrees ) in CEA patients ( P = .016). In all other head positions, there was no statistically significant difference in angulation change. There was no statistically significant difference in VFR change between groups in any of the head positions tested. CONCLUSIONS: There was a significant increase in ICA angulation in CAS patients if the head was bent forward; this was not observed in CEA patients. This angulation change did not lead to significant acute changes in cerebropetal blood flow, but it might have chronic effects not yet tested.

False lumen thrombectomy of the superior mesenteric artery followed by iliomesenteric bypass after Stanford type B aortic dissection.

A 55-year-old man with an acute Stanford type B aortic dissection presented with clinical signs of mesenteric ischemia. Computed tomography (CT) revealed a thrombosed false lumen in the superior mesenteric artery. At laparotomy, the dissection was found to be extending into the jejunal branches and medial colic artery. Thrombus was removed from the false lumen, and perfusion was restored with an iliomesenteric bypass, with the dissected layers tacked together in the suture line. A postoperative CT scan showed a stable diameter of the thoracoabdominal aorta and a patent iliomesenteric bypass.

Carotid stent mobility with regard to head movements: in vitro analysis.

Given that considerable motion of the carotid artery is present during head movements, we hypothesized that a flexible stent with low torsion might be favorable to avoid stress imparted to the stent and carotid artery. Therefore, we evaluated the flexibility of different expanded carotid stents before and after deployment in a carotid artery in vitro. Subsequently, we evaluated torsion of the bare expanded stents. Five stents (Wallstent [Boston Scientific Corp., Natick, MA], Acculink [Guidant Corp., Indianapolis, IN], Precise [Cordis Corp., Johnson & Johnson Company, Warren, NJ], Carotid SE [Medtronic AVE, Santa Rosa, CA], and Protégé [EV3, Plymouth, MN]) were tested. Flexibility was determined using a three-point bend test recording the bending load (BL) in grams required to flex the stent 25 degrees. Increased BL implies decreased flexibility. Torsion was measured by recording the rotation load (RL) in grams required to rotate the stents 30 degrees along its axis. Increased RL implies increased torsion. In the bare expanded state, the median BL was 6 g (range 1-22 g). The BL increased to 38 g (range 20-41 g) after deployment in a carotid artery, with the Carotid SE (21 g) and Wallstent (36 g) showing significantly lower BL (p < .0001 and p = .0016, respectively). Overall, the RL was 11 g (range 1-76 g). Significantly higher RL was required to rotate the Wallstent (73 g) and Precise (20 g) stents (p < .0001). The flexibility of the currently used stents decreases after deployment in a carotid artery irrespective of its flexibility in the bare state. Two stents showed increased torsion compared with the other stents. Limitations in both flexibility and torsion might influence the long-term performance of carotid angioplasty stenting.

Carotid artery dynamics during head movements: a reason for concern with regard to carotid stenting?

PURPOSE: To evaluate carotid artery mobility patterns during head movements following carotid angioplasty/stenting (CAS). METHODS: In 7 patients (all men; mean age 69 years, range 65-76) who had undergone unilateral CAS, 3D time-of-flight magnetic resonance angiography was performed, visualizing both carotid arteries in 5 different head positions (neutral, turned left and right, and bent forward and backward). Maximum intensity projection reconstructions were obtained to measure angulation at the proximal and distal stent junction. Configuration changes of the stented section of the carotid artery and the unstented contralateral artery were judged. Secondly, transverse sections at the level of the carotid bifurcation and at the skull base were used to calculate torsion shear in the common and internal carotid arteries (CCA, ICA) during left and right head position. Results were expressed as median (range). RESULTS: In neutral head position, maximal angulation at the distal stent junction was 34.3 degrees (32.3 degrees-55.6 degrees). With the head bent forward, this angulation changed to 47.6 degrees (42.6 degrees-85.2 degrees, p=0.028) and when bent backward to 26.5 degrees (25.0 degrees-48.7 degrees, p=0.027). In all patients, configuration changes of the stented sections were absent. The contralateral unstented side showed diffuse configuration changes without specific angulation at one location. With the head turned left and right, the CCA on the stented side was subjected to 28.6 degrees (13.6 degrees-53.7 degrees) and 24.9 degrees (2.0 degrees-50.6 degrees) of torsion shear, respectively. Torsion of the ICA was subsequently 18.1 degrees (12.7 degrees-40.5 degrees) and 15.2 degrees (2.9 degrees-69.4 degrees). CONCLUSIONS: Following carotid stenting, sharp ICA angulation that are aggravated by forward bending of the head occur at the distal stent junction. The stented section of the carotid artery shows complete lack of flexibility despite highly flexible features of hte stents ex vivo. Both the CCA and ICA are subjected to considerable torsion shear with the head turned left and right. This shear is not accommodated by the current stent designs.