| 1. |
- Malina, Martin, et al.
(författare)
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Endovascular AAA exclusion: will stents with hooks and barbs prevent stent-graft migration?
- 1998
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Ingår i: Journal of Endovascular Surgery. - 1074-6218. ; 5:4, s. 310-317
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate if stents with hooks and barbs will improve stent-graft fixation in the abdominal aorta. METHODS: Sixteen- to 24-mm-diameter Dacron grafts were deployed inside cadaveric aortas. The grafts were anchored by stents as in endovascular abdominal aortic aneurysm repair. One hundred thirty-seven stent-graft deployments were carried out with modified self-expanding Z-stents with (A) no hooks and barbs (n = 75), (B) 4 5-mm-long hooks and barbs (n = 39), (C) 8 10-mm-long, strengthened hooks and barbs (n = 19), or (D) hooks only (n = 4). Increasing longitudinal traction was applied to determine the displacement force needed to extract the stent-grafts. The radial force of the stents was measured and correlated to the displacement force. RESULTS: The median (interquartile range) displacement force needed to extract grafts anchored by stent A was 2.5 N (2.0 to 3.4), stent B 7.8 N (7.4 to 10.8), and stent C 22.5 N (17.1 to 27.9), p < 0.001. Both hooks and barbs added anchoring strength. During traction, the weaker barbs were distorted or caused intimal tears. The stronger barbs engaged the entire aortic wall. The radial force of the stents had no impact on fixation, while aortic calcification and graft oversizing had marginal effects. CONCLUSIONS: Stent barbs and hooks increased the fixation of stent-grafts tenfold, while the radial force of stents had no impact. These data may prove important in future endograft development to prevent stent-graft migration after aneurysm exclusion.
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| 2. |
- Malina, Martin, et al.
(författare)
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Late aortic arch perforation by graft-anchoring stent: complication of endovascular thoracic aneurysm exclusion
- 1998
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Ingår i: Journal of Endovascular Surgery. - 1074-6218. ; 5:3, s. 274-277
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To describe a fatal case of late aortic perforation by an endograft-anchoring stent. METHODS AND RESULTS: A 69-year-old woman presented 2 years after thoracoabdominal aneurysm repair with a 9-cm dilatation of the descending thoracic aorta proximal to the conventional aortic graft. A 38-mm Dacron graft with multiple Gianturco Z-stents sutured inside was placed transluminally across the aortic arch such that part of the uncovered portion of the proximal stent was partially across the left subclavian orifice. Four months later, the patient died from massive hemorrhage. Autopsy showed that the uncovered portion of the proximal stent had perforated the aortic arch. CONCLUSIONS: This case stresses the need for low-profile stent-grafts and smaller, more flexible introducer systems. Anchoring stents must be flexible, less traumatic, and strong enough to create a watertight seal even in tortuous vessels. To avoid aortic arch damage by thoracic stent-grafts, the proximal stent should be fully covered by the fabric.
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| 3. |
- Sonesson, Björn, et al.
(författare)
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Dilatation of the infrarenal aneurysm neck after endovascular exclusion of abdominal aortic aneurysm
- 1998
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Ingår i: Journal of Endovascular Surgery. - 1074-6218. ; 5:3, s. 195-200
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To determine the fate of the infrarenal aneurysm neck and suprarenal aorta after endovascular exclusion of abdominal aortic aneurysms (AAAs). METHODS: Thirty-four patients underwent endovascular AAA repair between January 1994 and December 1995 using custom-made stent-grafts constructed from polyester graft material and modified self-expanding Gianturco Z-stents sutured to the graft orifices. Thirty-one patients were available for follow-up. Pre- and postimplantation diameters were measured using spiral computed tomography in the infrarenal aneurysm neck and the suprarenal aorta at the level of the superior mesenteric artery (SMA). RESULTS: The mean follow-up time was 25 months. There was a significant increase of the diameter of the infrarenal aneurysm neck (+ 1.65 mm, p = 0.002), but not in the aorta at the level of the SMA (+0.52 mm, p = 0.100). There was no difference in the change in diameter in the infrarenal neck in the group with a stent adjacent to the level of measurement (n = 20) compared with the group without an adjacent stent (n = 11, p = 0.790). There was no correlation between preimplantation size of the infrarenal neck and its diameter change (r = 0.14, p = 0.488). There was no correlation (r = 0.10, p = 0.603) or association (chi-square test, p = 0.211) between aortic diameter change at the level of the SMA and the infrarenal neck. CONCLUSIONS: This investigation shows a significant dilatation of the infrarenal aneurysm neck, but not in the suprarenal aorta, after endovascular AAA repair with this device. The clinical significance of these findings is unclear. Whether such a dilatation in the infrarenal aneurysm neck may affect the long-term attachment of stent-grafts remains to be shown in the future.
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| 4. |
- Malina, Martin
(författare)
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Endovascular Repair of Abdominal Aortic Aneurysms. Aspects on a Novel Technique
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A new concept of treating abdominal aortic aneurysms was studied during a three-year period. Instead of open repair, graft insertion was accomplished endovascularly from the groins. The graft was attached by expandable stents to the non-dilated infrarenal aorta, i.e. the aneurysmal neck, and to the iliac artery/ies. Pre- and postoperative work-up included CT-scanning, angiography and ultrasonography on a regular basis. Six papers are included focusing on the fate of the excluded aneurysmal sac and on proximal stentgraft fixation. The median pulsatile wall motion of the sac was postoperatively reduced from 1 mm (I.Q.R 0.8 mm - 1.3 mm) to 0.3 mm (0.2 mm - 0.4 mm) and then remained stable. During the first year, the diameter of the sac was reduced by a median of 6 mm (2 mm 11 mm) but the neck dilated by 2 mm (0.5 - 3.5). Aneurysms with contrast accumulation in the sac (endoleak) were not reduced in size and the wall motion was ~50 % higher than expected. Rigid balloon-expanded stents detached in dilating porcine aortae. Self-expandable stents, on the other hand, complied with the pulsatile motion of the arterial walls and maintained apposition. In animal experiments, aortic stents placed over the renal arteries did not affect renal function and blood flow within one week. In a clinical trial, the proximal, graft anchoring stents, placed across the renal arteries, were not dislodged within six months. The renal function, as assessed by creatinine, CT-scanning, angiography and blood pressure was unaffected. Stents with hooks and barbs penetrating the aortic wall, improved stentgraft fixation tenfold in a cadaveric model.
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| 5. |
- Malina, Martin, et al.
(författare)
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Reduced pulsatile wall motion of abdominal aortic aneurysms after endovascular repair
- 1998
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Ingår i: Journal of Vascular Surgery. - 1097-6809. ; 27:4, s. 624-631
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The reduced size of abdominal aortic aneurysms (AAAs) after endovascular repair suggests lowered intraaneurysmal pressure. In the presence of endoleaks, the size is not decreased. Although postoperative intraaneurysmal pressure is difficult to record, the pulsatile wall motion (PWM) of aneurysms can be measured noninvasively. The aim of this study was to assess the PWM of AAAs before and after endovascular repair and to relate the change in the PWM to aneurysmal size and presence of endoleaks. METHODS: Forty-seven patients underwent endovascular repair of an AAA. The aneurysm diameter and PWM were measured with the use of ultrasonic echo-tracking scans preoperatively; at 1, 3, and 6 months; and thereafter biannually. Fifteen aneurysms developed endoleaks, whereas 32 were completely excluded. The leaks were characterized with the use of computed tomographic scanning and angiography. Median follow-up was 12 months (interquartile range, 5 to 24 months). RESULTS: The preoperative PWM of the aneurysms was 1.0 mm (range, 0.8 to 1.3 mm). After complete endovascular exclusion, the PWM was 25% (range, 16% to 37%) of the preoperative value (p < 0.001), and aneurysm diameter decreased by 8 mm (range, 6 to 14 mm) (p < 0.001). After 18 months, no further diameter reduction occurred. In three patients without endoleaks but with enlarging aneurysms, the postoperative PWM showed less reduction (p < 0.05). Aneurysms with endoleaks showed no diameter decrease, and the postoperative PWM was 50% higher than that in the totally excluded cases (p < 0.01). In five patients with transient endoleaks, the PWM was reduced after leakage ceased (p < 0.05). Leaks of various sources displayed similar PWM. CONCLUSION: The size and PWM of aneurysms are reduced after endovascular repair. The diameter reduction may cease after 1.5 years. Endoleaks are associated with higher PWM than expected. Pressure may be transmitted without evidence of leaks.
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| 6. |
- Resch, Tim, et al.
(författare)
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Persistent collateral perfusion of abdominal aortic aneurysm after endovascular repair does not lead to progressive change in aneurysm diameter
- 1998
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Ingår i: Journal of Vascular Surgery. - 1097-6809. ; 28:2, s. 242-249
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To differentiate between the phenomenon of collateral perfusion from a side branch versus graft-related endoleaks after endovascular repair of abdominal aortic aneurysms (AAA), with respect to aneurysm size and prognosis. METHODS: We successfully treated 64 AAA patients with endovascular grafting. We followed all the patients postoperatively with spiral computed tomography at one, three, six and 12 months, and biannually thereafter. We measured aneurysm diameters preoperatively and postoperatively. We calculated preoperatively the relation of maximum aortic diameter (D) to the thrombus-free lumen diameter (L) expressed as an L/D ratio. Median follow-up was 15 months. RESULTS: Sixteen patients had collateral perfusion during follow-up. We successfully treated two patients with embolization. One patient showed resolution of collateral perfusion after we stopped warfarin treatment. Two patients died of unrelated causes during follow-up. One patient was converted to surgical treatment, and two patients showed spontaneous resolution of their collateral perfusion. The group of patients with perfusion showed no statistically significant change of their aortic diameter on follow-up. The group of patients without perfusion showed a median decrease in aortic diameter of 8mm (p < 0.0001) at 18 months postoperatively. The group of patients with perfusion had significantly less thrombus in their aneurysm sac preoperatively than the group without perfusion, as expressed by the L/D ratio (mean L/D 0,61 versus 0,78, respectively; p=0.0021.) CONCLUSION: There was no significant increase in aortic diameter on an average 18 months postoperatively despite persistent collateral perfusion. This may indicate a halted disease progression in the short term. Embolization of collateral vessels is associated with risk of paraplegia. We recommend a conservative approach with close observation if aneurysm diameter is stable.
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