Mats Lindh

Changing aneurysmal morphology after endovascular grafting: relation to leakage or persistent perfusion

PURPOSE To relate changing abdominal aortic aneurysm (AAA) morphology after endovascular grafting to the presence of leakage, collateral perfusion, and other factors. METHODS Thirty-five patients who underwent successful AAA endovascular grafting were evaluated. Self-expanding Z-stents and Dacron grafts were applied in bifurcated and aortomonoiliac systems. Postoperative diameter changes were calculated from repeated spiral computed tomographic scans, angiograms, and ultrasonic phase-locked echo-tracking scans during a median 6-month follow-up (interquartile range [IQR] 3 to 12). RESULTS At 12 months, the diameters of completely excluded aneurysms had decreased 6 mm (IQR 2 to 11; p = 0.006). The proximal graft-anchoring stents had dilated 2 mm (IQR 0.5 to 3.3; p = 0.01). The aortic diameters immediately below the renal arteries but above the stents had not changed. Endoleakage and collateral perfusion (n = 13) were each associated with preserved aneurysm size and a 12 times higher risk of aneurysm dilation. After the leakage or the collateral perfusion had been treated, the aneurysm size decreased. Aneurysms with extensive intraluminal thrombi presented a reduced risk of leakage or perfusion. CONCLUSIONS The diameters of endovascularly excluded AAAs decrease, except in cases of leakage or perfusion. Careful follow-up of patients with aortic endografts is necessary.

Endovascular AAA Exclusion: Will Stents with Hooks and Barbs Prevent Stent-Graft Migration?

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.

Persistent collateral perfusion of abdominal aortic aneurysm after endovascular repair does not lead to progressive change in aneurysm diameter

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.

Dilatation of the infrarenal aneurysm neck after endovascular exclusion of abdominal aortic aneurysm

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.

Abdominal aortic aneurysms: experience with the Ivancev-Malmo endovascular system for aortomonoiliac stent-grafts

PURPOSE To describe a component-based aortomonoiliac stent-graft system and the first clinical results achieved with this device in endovascular abdominal aortic aneurysm (AAA) repair. METHODS From November 1993 to October 1996, 45 patients aged 60 to 86 years underwent endoluminal exclusion of true AAAs (median diameter 60 mm) involving the common iliac arteries (median diameter 16 mm right and 15 mm left) using unilimb stent-grafts deployed with the Iancev-Malmö system. RESULTS Six immediate conversions occurred in the beginning of the series due to endografts that were too short. Complications, including 2 inadvertent renal artery occlusions, 7 kinked grafts, 6 iliac artery dissections, and 3 perioccluder leaks, were prominent features in the first 15 patients. Five patients died in the postoperative period, four of whom were nonsurgical candidates. There were five significant stent-graft migrations: one 3 weeks after surgery due to mechanical injury of the proximal stent and four after 1 year owing to continuous dilation of a wide proximal neck, stent-graft placement in a conical, thrombus-lined proximal neck, and two instances of proximal extension separation from the main graft. Translumbar aneurysm perfusion required embolization in 3 patients. CONCLUSIONS Despite early complications associated with a learning curve, exclusion of large AAAs using unilimb stent-grafts is feasible. Strict inclusion criteria are necessary in order to improve mortality among nonsurgical candidates and minimize the risk for late migration.

Endovascular treatment of chronic mesenteric ischemia: report of five cases

AbstractPurpose: To evaluate the midterm results of percutaneous transluminal angioplasty (PTA) and stent placement in stenotic and occluded mesenteric arteries in five consecutive patients with chronic mesenteric ischemia. Methods: Five patients with 70%–100% obliterations of all mesenteric vessels resulting in chronic mesenteric ischemia (n= 4) and as a prophylactic measure prior to abdominal aortic aneurysm repair (n= 1) underwent PTA of celiac and/or superior mesenteric artery (SMA) stenoses (n= 2), primary stenting of ostial celiac occlusions (n= 2), and secondary stenting of a SMA occlusion (n= 1; recoil after initial PTA). All patients underwent duplex ultrasonography (US) (n= 3) and/or angiography (n= 5) during a median follow-up of 21 months (range 8–42 months). Results: Clinical success was obtained in all five patients. Asymptomatic significant late restenoses (n= 3) were successfully treated with repeat PTA (n= 2) and stenting of an SMA occlusion (n= 1; celiac stent restenosis). Recurrent pain in one patient was interpreted as secondary to postsurgical abdominal adhesions. Two puncture-site complications occurred requiring local surgical treatment. Conclusions: Endovascular techniques may be attempted prior to surgery in cases of stenotic or short occlusive lesions in patients with chronic mesenteric ischemia. Surgery may still be preferred in patients with long occlusions and a low operative risk.

Renal arteries covered by aortic stents: clinical experience from endovascular grafting of aortic aneurysms

OBJECTIVES During the endovascular repair of abdominal aortic aneurysms (AAAs), effective anchoring of the stent-graft is difficult in the presence of a short infrarenal aneurysm neck. The aim of this study was to investigate renal artery patency and renal function after deployment of graft anchoring stents across the renal arteries. DESIGN Retrospective open study. PATIENTS Twenty-five renal arteries, in 18 patients treated by endovascular exclusion of an AAA, were intentionally covered with the Gianturco Z-stent to ensure stent graft attachment. METHODS Renal artery patency was assessed by repeated spiral computed tomography (CT) scans and angiography. Creatinine levels, blood pressure and antihypertensive medication were recorded. Follow-up was a median 6 months (2-9). RESULTS All 25 stent-covered renal arteries remained patent. CT showed a small infarct in one kidney. Creatinine was 108 mumol/l (89-133) before intervention and 98 mumol/l (87-127) at follow-up. Blood pressure was 150/80 mmHg on both occasions. Antihypertensive therapy was intensified in one patient whose creatinine level remained stable and whose separate renin sampling was normal. CONCLUSIONS Covering the renal arteries with the Gianturco Z-stent does not seem to affect renal function within 6 months. Further follow-up is needed before suprarenal stent deployment can be advocated.

Long-term results of stenting for chronic iliac artery occlusion.

PURPOSE To evaluate the long-term results of stent placement for chronic occlusions of the iliac arteries. METHODS Between October 1992 and December 1997, 73 patients (40 men; median age 64 years, range 42-89) with 76 occluded iliac arteries (33 common, 34 external, and 9 both vessels) were treated with percutaneous recanalization and stenting using a variety of self-expanding and balloon-expandable devices. Median occlusion length was 7 cm (range 1-14). Follow-up consisted of clinical assessment, ankle-brachial index measurement, and arteriography or duplex ultrasound when indicated. RESULTS Anatomical success was achieved in 74 (97%) limbs. Seven (10%) patients experienced major complications: 2 distal embolizations, 2 arterial ruptures, 1 myocardial infarction, 1 groin hematoma requiring surgery, and 1 contrast-induced nephropathy. There was no 30-day mortality. Over a median follow-up of 27 months (range 1-75), there was 1 early occlusion (< or = 30 days) and 16 late recurrent lesions (11 occlusions and 5 stenoses) at a median 6.2 months (range 1.4-30). The recurrent lesions were treated with endovascular techniques in 8 limbs and surgery in 7 limbs (5 after failed endovascular procedures); 1 patient died before retreatment, and 1 patient refrained from further intervention. Primary and secondary patencies were 79% and 87% at 1 year and 69% and 81% at 3 years, respectively. CONCLUSIONS Stenting of chronic iliac occlusions is a safe and durable alternative to surgical treatment.

Chronic iliac vein occlusion: midterm results of endovascular recanalization.

Purpose: To evaluate patency and clinical outcome in patients treated with endovascular recanalization and stent placement for chronic iliac vein occlusions. Methods: During a 14-year period (1994–2008), 59 (38 women; median age 39 years) of 62 patients with chronic occlusion of the iliac vein segment in 66 limbs were successfully treated with endovascular recanalization and stent placement. A prospectively maintained database was analyzed retrospectively to obtain information on clinical details, endovascular techniques, and outcome. Results: Three (5%) procedures failed for technical reasons. Three (5%) complications occurred, 2 (3%) of which were perforations requiring transfusion and procedure termination. Initial clinical success after 6 months was achieved in 49 (83%) of the 59 patients successfully treated initially. Primary patency after a median imaging follow-up of 25 months was 67% (44/66), assisted primary patency was 75% (49/66), and secondary patency was 79% (52/66). Fifteen (23%) of 66 limbs were asymptomatic after a median clinical follow-up of 32 months, 34 (52%) limbs were improved, 13 (20%) were unchanged, and 4 (6%) were worse compared to before intervention. Actuarial primary, assisted primary, and secondary patency rates using Kaplan-Meier survival analysis were 70%, 73%, and 80%, respectively, at 5 years. Conclusion: Endovascular recanalization and stent placement is a safe and effective treatment for occluded iliac veins and adjacent segments. Clinical midterm results are encouraging. Recanalized and stented segments remain patent in the majority of patients after 2 years. Endovascular treatment can ease symptoms and prevent further deterioration of patients with post-thrombotic syndrome.

The effect of endovascular aortic stents placed across the renal arteries

OBJECTIVES To investigate renal artery patency and renal function after deployment of aortic stents covering the orifices of renal arteries. DESIGN Prospective open animal study. SETTING Department of Experimental Surgery at a university hospital. MATERIALS Twenty-three pigs were used. METHODS Ten pigs were observed for 1 h after graft-anchoring aortic stents, Gianturco (5) and Palmaz (5), were placed so that the stents covered the renal arterial orifices. In 13 pigs, Gianturco (6) and Palmaz (7) stents without grafts were placed over the renal arteries and left in situ for 7 days. Renal function and blood flow were measured by renograms, iohexol clearance and ultrasonic blood flow meter and patency was verified by angiograms. The kidneys were microscopically examined for signs of ischaemia and microemboli. RESULTS One renal artery covered by a graft-anchoring Gianturco stent occluded. The remaining renal arteries remained patent without any significant decrease in renal blood flow after stent deployment. Normal renal function and histology was maintained. CONCLUSIONS Aortic stents placed at the level of the renal arteries do not affect renal blood flow within 1 week in this experimental model. This may prove valuable in endovascular treatment of aortic aneurysms and in other procedures involving stents.