Editor's choice - A shaggy aorta is associated with mesenteric embolisation in patients undergoing fenestrated endografts to treat paravisceral aortic aneurysms.

OBJECTIVES: Bowel ischaemia is a life-threatening complication of endovascular aneurysm repair. This study aims to evaluate the factors associated with mesenteric ischaemia in patients undergoing fenestrated aortic endografts to treat paravisceral aneurysms. METHODS: Consecutive patients undergoing double or triple fenestrated stent graft insertion were retrospectively analysed. No patients were declined surgery based on anatomic complexity. Preoperative demographics, procedure-related variables, and anatomical factors were examined. Using 3D software, the aortic thrombus volume from the coeliac axis to the lowest renal, aortoiliac tortuosity, and aortic irregularity index (as graded by 3 independent assessors, graded 0-3 based on severity) were compared. Univariate analysis was performed to identify risk factors for the development of bowel ischaemia. RESULTS: Ninety-nine patients underwent elective aneurysm repair (64 triple fenestrations and 35 double fenestrations), 5% of which developed bowel ischaemia, and of these 80% (4/5) died. Mesenteric ischaemia was significantly associated with increased aortic irregularity (median [range], 2 [1-3] vs. 1 [0-2], p = .005, ischaemia vs. no ischaemia) and increased thrombus volume (37 ± 8 vs. 21 ± 12, p = .007) but not aortoiliac tortuosity (1.4 [1.2-1.5] vs. 1.30 [1.2-1.7], p = .3), inferior mesenteric or internal iliac artery patency. Mesenteric ischaemia was also associated with a significantly higher preoperative creatinine (mean ± SD: 183 ± 74 vs. 111 ± 43, p = .007). CONCLUSIONS: The presence of aortic irregularity and increased thrombus volume in the paravisceral segment predicts the occurrence of mesenteric and renal ischaemia in patients treated with fenestrated endografts. This is likely to be related to graft manipulation and catheterisation of visceral vessels.

Fenestrated endovascular aneurysm repair.

BACKGROUND: Fenestrated endovascular aneurysm repair (FEVAR) is a technically challenging operation. The duration, blood loss, and risk of limb ischaemia, contrast-induced nephropathy and reperfusion injury are likely to be higher than after standard endovascular aneurysm repair (EVAR). Benefits of FEVAR over open repair may be less than those seen with standard infrarenal EVAR. This paper is a meta-analysis of observational studies of all published data for FEVAR, with the aim to highlight current issues around the evidence for the potential benefit of FEVAR. METHODS: A search was performed for studies describing FEVAR for juxtarenal abdominal aortic aneurysms. Small series of fewer than ten procedures and studies describing predominantly branched endografts or FEVAR for aortic dissection were excluded. Authors of included papers were contacted to eliminate patient duplication. RESULTS: Eleven studies were identified describing a total of 660 procedures. Definitions of aneurysm morphology were variable, and clear inclusion and exclusion criteria were not always documented. Double fenestrations were more common than triple or quadruple fenestrations. Target vessel perfusion rates ranged from 90·5 to 100 per cent. Eleven deaths occurred within 30 days, giving a 30-day proportional mortality rate of 2·0 per cent. Morbidity was poorly reported. CONCLUSION: FEVAR for repair of suprarenal and juxtarenal aneurysms is a viable alternative to open repair. However, there is no level 1 evidence for FEVAR, and current evidence is weak with many unanswered questions.

Mid-term outcome of endovascular revascularization for chronic mesenteric ischaemia.

BACKGROUND: : This study aimed to assess mid-term outcome after endovascular revascularization of chronic occlusive mesenteric ischaemia (CMI) and to identify possible predictors of mortality. METHODS: : Consecutive patients undergoing primary elective stenting for CMI between 1995 and 2007 were registered prospectively in a database. Patients with acute ischaemia were excluded. Retrospective case-note review and data analysis were performed. RESULTS: : Forty-three patients (10 men) were treated for stable (n = 30) or exacerbated (n = 13) CMI. Their median (interquartile range (i.q.r.)) age was 70 (60-79) years. Revascularization was successful in 47 of 49 vessels. The superior mesenteric artery (SMA), either alone (n = 34) or in combination with the coeliac trunk (n = 6), was the predominant target vessel. No patient died within 30 days. Median follow-up was 43 (i.q.r. 25-63) months and the estimated (s.e.) 3-year overall survival rate was 76(7) per cent. Two patients died from distal SMA occlusive disease and intestinal infarction after 6 and 18 months respectively. Previous stroke (P = 0.016), male sex (P = 0.057) and age (P = 0.066) were associated with mid-term mortality on univariable, but not multivariable analysis. Reintervention was needed in 14 patients, achieving a 3-year cumulative rate of freedom from recurrent symptoms of 88(5) per cent. CONCLUSION: : Endovascular treatment provided high early and mid-term survival rates in this series of patients with CMI, with low complication rates.

Intra-aneurysm sac pressure in patients with unchanged AAA diameter after EVAR.

OBJECTIVE: To study intra-aneurysm sac pressure and subsequent abdominal aortic aneurysm (AAA) diameter changes in patients without endoleaks that remain unchanged in AAA diameter more than 1 year after endovascular aneurysm repair (EVAR). METHODS: A total of 23 patients underwent direct intra-aneurysm sac pressure (DISP) measurements 16 months (IQR: 14-35 months) after EVAR. Tip-pressure sensors were used through translumbar AAA puncture. Mean pressure index (MPI) was calculated as the percentage of mean intra-aneurysm pressure relative to the simultaneous mean intra-aortic pressure. Aneurysm expansion or shrinkage was assumed whenever the diameter change was > or =5mm. Values are presented as median and interquartile range. RESULTS: In 18 patients, no fluid was obtained upon AAA puncture (group A). In five patients, fluid was obtained (group B). In group A, follow-up continued for 29 months (IQR: 15-35 months) after DISP; five AAAs shrank, 10 remained unchanged and three expanded (MPIs of 26% (IQR: 18-42%), 28% (IQR: 20-48%) and 63% (IQR: 47-83%) and intra-sac pulse pressures of 3 mmHg (IQR: 0-5 mmHg), 4 mmHg (IQR: 2-8mm Hg) and 12 mmHg (IQR: 6-20 mmHg), respectively, for the three subgroups). MPI and intra-sac pulse pressures were higher in AAAs that subsequently expanded (P=0.073 and 0.017, respectively). MPI and pulse pressure correlated with total diameter change (r=0.49, P=0.039 and r =0.39, P=0.109, respectively). Pulse pressure had a greater influence than MPI on diameter change (R(2)=0.346, P=0.041, beta standardised coefficient of 0.121 for MPI and 0.502 for pulse pressure). Similar results with stronger, and significant correlation to pulse pressure were obtained when relative diameter changes were used (r=0.55, P=0.017). In group B, MPI and AAA pulse pressure were 32% (IQR: 18-37%) and 1 mmHg (IQR: 0-6 mmHg), respectively. After 36 months (IQR: 21-38 months), one AAA shrank, three continued unchanged while one expanded. CONCLUSIONS: AAAs without endoleak and unchanged diameter more than 1 year after EVAR will often continue unchanged. Expansion can eventually occur in the absence of intra-sac fluid accumulation and is associated with higher and more pulsatile intra-sac pressure. However, in patients with intra-sac fluid, expansion can occur with low intra-sac pressures.

Ready-to-fenestrate stent grafts in the treatment of juxtarenal aortic aneurysms: proposal for an off-the-shelf device.

OBJECTIVE: A prototype ready-to-fenestrate stent graft (RFSG) was designed with a fixed scallop, and eight potential fenestrations allowing for variation in the position of each renal artery (RA) relative to the superior mesenteric artery (SMA). We aimed to determine the proportion of juxtarenal aneurysms treatable using this potentially 'off-the-shelf' device. METHODS: A total of 439 consecutive orders for custom-made devices were analysed, and positions for potential fenestrations in the RFSG were determined, based on the most frequent anatomical target vessel variations: a fixed SMA scallop 12 mm deep at 12:00, RA fenestrations at 9:15, 10:15 (target within the range 8:45-10:45), 2:15 and 3:15 (target within the range 1:45-3:45), each either 19 or 28 mm from the graft edge (GE); (within the range 15-32 mm), and 6 x 8 mm in diameter. Proximal diameters of 24, 26, 28, 30, 32 and 36 mm were chosen. RESULTS: Of the 439 plans, 372 standard juxtarenal (SJR) cases, defined by the inclusion of a scallop and 0, 1 or 2 small fenestrations (12%, 13% and 75% of the cases, respectively) were identified and used to test the applicability of the model. Mean CP (clock position) for right RA was 9:30, for the left RA 3:00, being a mean of 21 +/- 5 and 22 +/- 5 mm, respectively from the GE. RA CP was within the RFSG range in 86% (right) and 88% (left) of the cases, with 96% and 98%, respectively, within the allowable distance from the GE. A total of 81% of all SJR cases were potentially treatable using the RFSG model. CONCLUSIONS: An RFSG device would allow for the treatment of the majority of juxtarenal aortic aneurysms, which currently require custom-made devices.

Techniques for supra-aortic trunk preservation in thoracic endovascular aneurysm repair.

Stent graft placement for aneurysmal disease of the aortic arch and proximal descending aorta is limited by the need to preserve flow to the supra-aortic trunks. Whilst extra-anatomical bypass and procedures combining open and endovascular arch repair are currently used in this setting, less invasive totally endovascular solutions have been described. These include in-situ fenestration of a thoracic stent graft using a retrograde approach from the target vessel to the lumen of the main device, to which it is connected by a smaller covered stent. Alternatively, so-called 'chimney' stents have been used, placing a parallel stent alongside the main device, connecting the aortic branch vessel with the native aortic lumen proximal to the seal zone of the main thoracic device. We review these techniques and discuss the merits and potential disadvantages of each procedure.

Is there a benefit of frequent CT follow-up after EVAR?

OBJECTIVE: Imaging follow-up (FU) after endovascular aneurysm repair (EVAR) is usually performed by periodic contrast-enhanced computed tomography (CT) scans. This study aims to evaluate the effectiveness of CT-FU after EVAR. METHODS: In this study, 279 of 304 consecutive patients (261 male, aged 74 years (interquartile range (IQR): 70-79 years) with a median abdominal aortic aneurysm (AAA) diameter of 58 mm (IQR: 53-67 mm)) underwent at least one of the yearly CT scans and plain abdominal films after EVAR. All patients received Zenith stent-grafts for non-ruptured AAAs at a single institution. Patients were considered asymptomatic when a re-intervention was done solely due to an imaging FU finding. The data were prospectively entered in a computer database and retrospectively analysed. RESULTS: As a follow-up, 1167 CT scans were performed at a median of 54 months (IQR: 34-74 months) after EVAR. Twenty-seven patients exhibited postoperative AAA expansion (a 5-year expansion-free rate of 88+/-2%), and 57 patients underwent 78 postoperative re-interventions with a 5-year secondary success rate of 91+/-2%. Of the 279 patients, 26 (9.3%) undergoing imaging FU benefitted from the yearly CT scans, since they had re-interventions based on asymptomatic imaging findings: AAA diameter expansion with or without endoleaks (n=18), kink in the stent-graft limbs (n=4), endoleak type III due to stent-graft limb separation without simultaneous AAA expansion (n=2), isolated common iliac artery expansion (n=1) and superior mesenteric artery malperfusion due to partial coverage by the stent-graft fabric (n=1). CONCLUSIONS: Less than 10% of the patients benefit from the yearly CT-FU after EVAR. Only one re-intervention due to partial coverage of a branch by the stent-graft would have been delayed if routine FU had been based on simple diameter measurements and plain abdominal radiograph. This suggests that less-frequent CT is sufficient in the majority of patients, which may simplify the FU protocol, reduce radiation exposure and the total costs of EVAR. Contrast-enhanced CT scans continue, nevertheless, to be critical when re-interventions are planned.

Early and intermediate outcome of emergency endovascular aneurysm repair of ruptured infrarenal aortic aneurysm: a single-centre experience of 90 consecutive patients.

OBJECTIVE: To evaluate the early and intermediate outcome of a consecutive series of emergency endovascular aneurysm repairs (eEVAR) of computed tomography (CT)-verified infrarenal ruptured abdominal aortic aneurysm (rAAA) at a single tertiary referral centre. METHODS: Prospectively collected data of patients operated between April 2000 and October 2007 were retrospectively reviewed and all their pre-, intra- and postoperative imaging were re-evaluated. Patient and procedural data were analysed using a Cox multiregression model. RESULTS: Ninety patients (86% men, aged 76 (+/-7) years), were identified and included in the analysis. Symptom duration was <3h in 22% of patients, 3-24h in 39% and >24h in 39%. Mean aneurysmal diameter was 73 (+/-14)mm. All patients were treated with the COOK Zenith stent-graft (56% bi-iliac and 44% uni-iliac). Sixty-one percent were haemodynamically unstable on presentation, and 26% required an intra-operative aortic occlusion balloon to maintain haemodynamic stability. The 30-day and 1-year mortality rates were 27% and 37%, respectively. One-year aneurysm-related mortality was 33%. Twenty-eight percent of patients required re-interventions during the follow-up. The use of an aortic occlusion balloon and the presence of cerebrovascular disease or obstructive lung disorder correlated significantly with 30-day mortality in the multivariate analysis. CONCLUSION: EVAR is a valid treatment option for rAAA when used as a first-line method for all patients.

Predictors of long-term beneficial effects on blood pressure after percutaneous transluminal renal angioplasty in atherosclerotic renal artery stenosis.

AIM: This retrospective study evaluated long-term effects of percutaneous transluminal renal angioplasty (PTRA) in atherosclerotic renal artery stenosis (ARAS), and predictors of benefit on blood pressure (BP). METHODS: During 1997-2003, 234 patients (age 69+/-11 years, 138 [59%] males) underwent PTRA for ARAS at Malmö Vascular Centre. Cure was defined as diastolic (D)BP<90 mmHg and systolic (S)BP <140 mmHg off antihypertensive medication. Improvement was defined as DBP <90 mmHg and/or SBP <140 mmHg on the same or reduced number of medications, or reduction in DBP of >or=15 mmHg with the same or reduced number of medications. Benefit was defined as cure or improvement. RESULTS: After PTRA, SBP and DBP decreased (P<0.001), and remained lower (P<0.001) until last follow-up after 4.1+/-3.3 years. Antihypertensive medication decreased (P<0.001), and remained lower at one month (P<0.001), one year (P<0.01), and last follow-up (P<0.05). Renal function was unchanged until last follow-up, when it deteriorated (P<0.001). Patients showing benefit of PTRA on BP at last follow-up (N.=150 [64%]) used more antihypertensive drugs before PTRA (P=0.012), especially angiotensin converting enzyme inhibitors (ACEi) or angiotensin II receptor blockers (ARBs) (P=0.010), and diuretics (P=0.015). In logistic regression, use of ACEi or ARBs failed to reach significancy (P=0.054). Patients dying during follow up (N.=100 [43%]) showed higher age (P<0.0001) and s-creatinine (P<0.0001), lower glomerular filtration rate (P<0.0001), and higher frequency of diabetes mellitus (P<0.005). In logistic regression only age (P=0.009) and diabetes mellitus (P=0.014) predicted mortality. CONCLUSIONS: We confirmed beneficial effects on BP with PTRA in ARAS. ACEi, ARB and diuretic treatment before PTRA predict favourable long-term BP-response in univariate analysis.

EVAR of aortoiliac aneurysms with branched stent-grafts.

INTRODUCTION: Branched iliac stent-grafts (bSG) have recently been developed in order to preserve internal iliac artery (IIA) flow in patients with aneurysmal or short common iliac arteries. The aim of this study is to evaluate a single-center experience with bSG for the IIA. METHODS: Twenty-two male patients (70 (IQR 65-79) years old) underwent EVAR with 23 bSG (1 bilateral repair) between September 2002 and August 2007. Median AAA diameter was 52 (37-60) mm while common iliac diameter on the side of the bSG was 34 (27-41) mm. Two in-house modified Zenith SG and subsequently 21 commercially available bSG (18 Zenith Iliac Side and 3 Helical Branches) were used. Follow-up (FU) included CT at one month and yearly thereafter. Data was prospectively entered in a database. RESULTS: Primary technical success was 91% (21 bSG). Median FU duration was 20 (8-31) months. One patient (5 %) died after discharge from acute myocardial infarction on day 13. Another patient died 30 months after EVAR of an unrelated cause. The overall bSG patency was 74% due to 6 branch occlusions (2 intraoperative and 4 late). All patients with patent bSG were asymptomatic. Three occlusions were asymptomatic findings on CT, while the other three developed claudication (two patients with contralateral IIA occlusion and one with simultaneous occlusion of the external iliac). One patient (5%) developed an asymptomatic type III endoleak at 1 month and was successfully treated with a bridging SG. Overall, four patients (18%) required reinterventions (1 bilateral stenting of the external iliac arteries, 1 external and 1 internal SG extensions and 1 femoro-femoral cross-over bypass). Nine out of 16 patients (56%) with CT-FU>/=1 year had shrinking aneurysms. There were no postoperative aneurysm expansions. CONCLUSIONS: EVAR of aortoiliac aneurysms with IIA bSG is a good alternative to occlusion of the IIA in patients with challenging distal anatomy.

Kissing stents in the aortic bifurcation--a valid reconstruction for aorto-iliac occlusive disease.

OBJECTIVE: To evaluate outcome and patency predicting factors of kissingstent treatment for aorto iliac occlusive disease (AIOD). METHODS: Patients treated with kissingstents for AOID between 1995 and 2004 at a tertiary referral center were identified through local databases. Chart review and preoperative images were used for TASC and Fontaine classification. Follow-up consisted of clinical exams, ABI and/or duplex. Patency rates were estimated by Kaplan-Meier analysis, and Cox multivariate regression was used to determine factors associated with patency. RESULTS: 173 consecutive patients (46% male, mean 64 years) were identified. TASC distribution was: A 15%, B 34%, C 10%, D 41%. Mean follow-up was 36 months (range: 1-144). 30-day mortality was 1% (2 patients), and 1-year survival was 91% (157 patients). 2 patients underwent late, open conversion and 13 patients suffered minor puncture site complications. Primary, assisted primary and secondary patency was: 97%, 99% and 100%, and 83%, 90% and 95% at twelve and 36 months respectively. There was no significant difference in patency between the TASC groups. Patency was significantly worse for patients in Fontaine class III. CONCLUSIONS: Aortoiliac kissing stents is a valid alternative to open repair for TASC A-D lesions. The procedure has low mortality and morbidity and good patency at 3 years.

What to do when evidence is lacking--implications on treatment of aortic ulcers, pseudoaneurysms and aorto-enteric fistulae.

UNLABELLED: Present knowledge on natural history and how to treat penetrating aortic ulcers or different forms of pseudoaneurysms with or without infection is limited as there are only case reports and small series of unusual aortic pathology and its treatment available. MATERIAL: From our centre we collected 65 patients treated with open (n = 15) or endovascular reconstruction (n= 50) during a 20-year period in the abdominal aorta. These patients are presented including a review of contemporary treatment. RESULTS: Endovascular reconstructions seem to reduce morbidity and mortality compared to otherwise extensive open surgery. Even for patients with infectious etiology (mycotic aneurysms, aorto-enteric fistula) endovascular treatment may be a first-hand option bridging to a more elective open repair. However, a large proportion of patients being unfit for further open surgery were solely treated endovascularly and had no major infectious complications in the follow-up. Registers of cases with unusual aortic pathology, not only of those treated but also of those managed conservatively, are needed to define who to treat and if endovascular or open repair should be recommended. CONCLUSION: Endovascular technique is a promising technique for treatment of aortic pseudoaneurysms of different etiologies. We firmly recommend, despite the lack of evidence, that the work up of patients with penetrating aortic ulcers, mycotic or other types of pseudoanerysms as well as aorto-enteric fistulae should enclose both endovascular and open (or combined) treatment modalities. However, our knowledge of the natural history is limited. Therefore, registers of cases with unusual aortic pathology, not only of those treated but also of those managed conservatively, are needed to define who to treat and if endovascular or open repair should be recommended.

Remodeling of the thoracic aorta after stent grafting of type B dissection: a Swedish multicenter study.

AIM: Endovascular repair of complicated type B dissections has evolved as a promising alternative to open repair. Previous studies have indicated that continued false lumen flow is a predictor of continued aortic dilatation and risk of rupture during follow-up. This multicenter study was conducted to analyze the postoperative changes of the false lumen after endografting of complicated type B dissections. METHODS: All patients treated with endovascular stent grafts for thoracic type B dissections at 5 major Vascular Centers in Sweden were identified through local databases. Review of charts and all available pre- and postoperative CT scans were performed to identify demographics, indications for repair as well as postoperative changes of the aorta and false lumen. RESULTS: A total of 129 patients treated for type B dissections between 1994 and December 2005 were identified. Median radiological follow-up was 14 months. Fourteen patients died perioperatively leaving 115 patients available for analysis. Seventy-four of these had CT imaging of sufficient quality for morphological analysis. The vast majority of acute patients were treated for rupture or end-organ ischemia whereas most chronic patients were treated for asymptomatic aneurysms. In 80% of patients, the false lumen thrombosed along the stent graft but it remained perfused distal to the stent graft fixation in 50% of patients. Only 5% of patients presented with aortic enlargement of the stent grafted area when adequate proximal sealing was achieved. The distal, uncovered aorta displayed expansion in 16% of patients. CONCLUSIONS: The stent grafted thoracic aorta after type B dissection appears to be stabilized by covering the primary entry site with a stent graft in the majority of both acute and chronic dissections. The uncovered portion of the aorta distal to the stent graft, however, remains at risk of continuous dilatation. Stent grafting for complicated type B thoracic dissections seems to be a treatment option with reasonable morbidity and mortality even though the incidence of severe complications is still significant.

Revascularisation of renal artery stenosis caused by fibromuscular dysplasia: effects on blood pressure during 7-year follow-up are influenced by duration of hypertension and branch artery stenosis.

Fibromuscular dysplasia (FMD) mainly affects renal arteries. Percutaneous transluminal renal angioplasty (PTRA) and surgery are effective treatments, but long-time follow-up is lacking. Retrospective follow-up for 7.0+/-4.7 years of 69 consecutive patients (age 44+/-13 years) treated for hypertension due to FMD, 59 patients underwent PTRA and eight patients surgery. In two patients no PTRA was performed. Technical success was achieved in 56 (95%) patients undergoing PTRA and all eight undergoing surgery. After successful PTRA, both systolic and diastolic blood pressures (SBP and DBP) had decreased at discharge (from 174+/-33/100+/-13 to 138+/-19/80+/-15 mmHg; P<0.0001), and remained lower at 1 month, 1 year, and last follow-up after 7.0+/-4.7 years (140+/-25/83+/-12 mmHg; P<0.0001). Serum-creatinine had decreased both at 1 year (from 84+/-28 to 75+/-13 micromol/l; P=0.0030) and last follow-up (75+/-16 micromol/l; P=0.0017). The number of antihypertensive drugs decreased (from 2.3+/-1.2 before PTRA to 1.4+/-1.3 at discharge and at 1 month; P<0.0001, and 1.6+/-1.5 at last follow-up; P=0.0011). SBP decreased more after PTRA among patients with FMD only in the main renal artery than in those with branch artery involvement (43+/-29 vs 20+/-41 mmHg; P=0.0198). Beneficial effects on BP, creatinine and antihypertensive drugs also occurred after surgery. Patients on antihypertensive drugs at last follow-up had longer hypertension duration before PTRA than those without (5.9+/-7.7 vs 1.8+/-4.1 years; P=0.0349). Cure was achieved in 16 (24%), improvement in another 26(39%), and benefit in 42(63%). In conclusion, renal artery FMD, PTRA and surgery have beneficial long-term effects, negatively affected by hypertension duration and branch artery involvement.

Endografting of thoracic aortic aneurysms and dissections.

3D imaging and endovascular repair have greatly increased the number of interventions in the thoracic aorta. Excellent early results of endovascular repair compensate unproven long term durability. Challenging anatomy is associated with increased risk for late failure of the stent graft (SG) but the option of open repair usually remains and complications from open surgery are also more frequent in these cases. The indications for endovascular repair of the descending aorta include aneurysms larger than 5-6 cm in diameter, pseudoaneurysms and type B dissection complicated by rupture, aortic dilation or distal hypoperfusion. Traumatic transections and certain types of coarctation are also treated endovascularly. Aortic rupture is associated with a high mortality and treatment is attempted liberally. Logistics remain a limitting factor for urgent stent grafting in many centers. Adequate pre and intraoperative imaging is mandatory for correct SG implantation. The mechanical forces of aortic blood flow jeopardize durable fixation of the device. Extended fixation zones of at least 5 cm, generous overlap between SG components and SG positioning along the outer curvature of the sac improve durability. Primary complications include stroke and paraplegia in about 5% of the cases. Late complications are mainly associated with SG dislodgement and inadequate seal. Surveillance is required. Future development focuses on treatment of leasions in the aortic arch. Debranching of the arch and branched SGs are currently being investigated.

Changes in aneurysm morphology and stent-graft configuration after endovascular repair of aneurysms of the descending thoracic aorta.

OBJECTIVE: We sought to study changes in morphology and stent-graft configuration of descending thoracic aortic aneurysms after endovascular repair. METHODS: Twenty-three patients treated with custom-made stent-grafts were studied. The stent-graft consisted of continuous, stainless-steel Z stents mounted within a polyester graft. In the last 11 cases the stents were interconnected with 3 longitudinal wires. Contrast-enhanced spiral computed tomography was performed preoperatively and at 1, 3, and every 6 months postoperatively. Angiography was used preoperatively and at 1-year follow-up. Proximal and distal necks were assessed for diameter and length. Aneurysm diameter, endoleaks, stent-graft migration, and changes in stent-graft configuration were evaluated. RESULTS: During follow-up (median, 18 months; range, 1-48 months), excluded aneurysms decreased in diameter by 4 mm (0.5-10 mm, P =.0018). Endoleaks prevented size decrease. Five patients displayed neck dilatation, 4 at both the proximal and distal fixation sites and 1 only distally. In 7 (30%) patients there was proximal migration of the distal end of the stent-graft. Three (13%) patients displayed both distal migration of the proximal end of the stent-graft and proximal migration of the distal end of the stent-graft. There was a significant correlation between stent-graft kinking and appearance of proximal or distal stent-graft migration (P =.05 and P =.0007, respectively). In no case did the migration lead to appearance of an endoleak before intervention was performed. CONCLUSION: Excluded descending thoracic aortic aneurysms decrease in size on midterm follow-up. A subgroup of patients prone to neck dilatation might exist. A combination of neck dilatation and vector forces acting on stent-grafts in the tortuous thoracic aorta might lead to stent-graft migration.

Peribiliary plexa--important pathways for shunting of iodized oil and silicon rubber solution from the hepatic artery to the portal vein. An experimental study in rats.

OBJECTIVES: Iodized oil is commonly used in chemoembolization of hepatic tumors, and silicon rubber solution is used for casting studies of hepatic tumor vasculature. Understanding the distribution patterns of iodized oil and silicon rubber solution is of significance in the refinement of iodized oil techniques and proper interpretation of hepatic tumor vascular studies. In this study, the location for iodized oil and silicon rubber solution shunting from the hepatic artery to the portal vein was identified. METHODS: Iodized oil and silicone rubber solution were injected into the hepatic artery in rats. The porta hepatis and the liver periphery were examined using in vivo microscopy. RESULTS: Iodized oil and silicone rubber solution had identical distribution patterns in the hepatic circulation. Both were shunted in large quantities from the hepatic artery into the portal vein through the peribiliary plexa. Other potential shunting sites did not contribute to the shunting. CONCLUSIONS: Though of different chemical natures, iodized oil and silicon rubber solution share similar distribution patterns in the liver. Hepatic arterioportal shunting of these substances occurs via the peribiliary plexa.

Angiographic studies of the totally arterialized rat liver.

Twenty-three angiographies were performed in 20 rats with a totally arterialized liver. The arterialization was obtained by the construction of an end-to-side portacaval shunt (PCS) and an arteriovenous (AV) fistula between the left gastric artery and the portal stump. Microsurgical technique was necessary because of the small diameter of the AV fistula (0.5 mm). The angiographic examinations showed an AV fistula patency rate of 70% and a PCS rate of 100%. A successively increasing diameter of the fistula with dilation of the intrahepatic portal vessels was demonstrated in the rats with a patent arterioportal fistula. Tortuous and irregular vessels were also observed. All these signs suggest an overarterialization which developed despite the use of a very small AV fistula. None of the three rats examined histologically had cirrhosis of the liver. Further research is needed to attempt to avoid or minimize the deleterious effects of overarterialization of the portal tree, while utilizing the advantages of a dual liver blood supply in patients with decompressive PCS.

Interventional radiology of the biliary tract. Metallic stents.

Biliary metallic stents were placed in 18 patients with bile duct obstruction. Six patients received Gianturco stents and 14 Wall-stents. Results of these tests are discussed.