Value of diffusion-weighted MRI during carotid angioplasty and stenting.

INTRODUCTION: The incidence of neurological injury following carotid angioplasty and stenting is of great interest to those advocating it as an alternative to endarterectomy in the management of critical carotid stenosis. A significant inter-observer variation exists in determining the presence or absence of a neurological deficit following the procedure objective imaging would be advantageous. In this study, we sought to assess diffusion weighted MRI as a diagnostic tool in evaluating the incidence of neurological injury following carotid angioplasty and stenting (CAS). PATIENTS AND METHODS: The first 110 cases of CAS in our unit were included in this series. The procedure was abandoned in three patients. Patients underwent intracranial and extracranial MR angiography, together with diffusion-weighted MRI (DWI) prior to and following CAS and had a formal neurological assessment in the intensive care unit after the procedure. RESULTS: One hundred and ten Procedures were attempted in 98 patients. Twenty-eight percent were asymptomatic. Following CAS, 7.2% of patients had a positive neurological exam (two major strokes with one fatality) and 21% had positive DWI scans, equating to a sensitivity of 86% and a specificity of 85% for DWI in detecting cerebral infarction following CAS. The positive predictive value of the test was 0.3 and negative predictive value 0.99. The major stroke and death rate was 1.8%. While the use of a cerebral protection device appeared to significantly reduce the incidence of cerebral infarction (5% vs. 25%, p = 0.031) this may be a reflection of the learning curve encountered during the study. CONCLUSION: The incidence of subclinical DWI detected neurological injury was significantly higher than clinical neurological deficit following CAS. Conventional methods of neurological assessment of patients undergoing CAS may be too crude to detect subtle changes and more sensitive tests of cerebral function are required to establish whether these subclinical lesions are relevant.

Use of the percutaneous vascular surgery device for closure of femoral access sites during endovascular aneurysm repair: lessons from our experience.

OBJECTIVES: to evaluate the results of our early experience with a percutaneous closure device for aortic aneurysm repair and to identify device related and patient related factors leading to procedure failure. METHODS: eighty-two percutaneous closures in forty-four patients was performed using the 10F Prostar XL Percutaneous Vascular Surgery device during the repair of 1 iliac, 1 thoracic and 42 abdominal aortic aneurysms. RESULTS: successful closure was achieved in 70 access sites (85%) with 12 sites requiring conversion to an open groin incision. The reasons for failure include difficult device introduction due to a tortuous iliac, deflection of needles due to previous scar, femoral artery occlusion and failure of the device to close the arteriotomy. There was one intraoperative death from retroperitoneal haemorrhage and another patient developed a pseudoaneurysm at the cannulation site. CONCLUSIONS: use of the percutaneous closure device requires very careful patient selection. Preoperative radiological assessment of the ilio-femoral vessels is vital to assess for cacification and tortuosity. High device failure rates can be expected from obese patients and those with scarred groins. When difficulty is encountered during the procedure, there should be a low threshold for conversion to an open groin incision. The device and the method of introduction can be further improved to address some of these issues.

Does the Mediterranean paradox extend to abdominal aortic aneurysm?

BACKGROUND: We sought to test, in men undergoing ultrasound screening for abdominal aortic aneurysms (AAA) in Western Australia, clinical impressions that the prevalence of AAA is high in Dutch migrants and low in migrants from Mediterranean countries. METHODS: In a population-based trial, men undergoing screening for AAA completed a questionnaire covering their place of birth, smoking habits and consumption of alcohol, meat, fish, salt and milk. We examined the variation by place of birth in the mean, median, 95th and 99th centiles of infrarenal aortic diameter and the prevalences of AAA defined by criteria of 30 mm, 50 mm and by the 95th and 99th centiles, in men born in Australia, of aortic diameter adjusted for height. FINDINGS: Overall, 12,203 (70.5%) of the 19 583 men took up the invitation to undergo ultrasound screening. The prevalence of AAA defined by absolute diameter was higher than average in men born in The Netherlands or Scotland (more of whom had ever smoked or smoked currently) and lower in men of Mediterranean origin (more of whom drank alcohol currently). There were no consistent relationships with simple dietary data. Correction of aortic diameter for height eliminated the significant heterogeneity in prevalence of large AAA, although a threefold variation in prevalence of AAA exceeding the 95th centile of height-adjusted diameter in Australian men persisted. INTERPRETATION: In our cohort of men, which is subject to both 'healthy migrant' and 'survivor' effects, if it exists at all, any 'Mediterranean paradox' for AAA is more modest than that for coronary disease.

Evaluation of patient selection guidelines for endoluminal AAA repair with the Zenith Stent-Graft: the Australasian experience.

PURPOSE: To review the patient selection guidelines for endovascular repair of abdominal aortic aneurysms (AAA) using the Zenith Endovascular Graft and establish an order of importance for each criterion. METHODS: The Zenith Endovascular Graft Research Database was interrogated for information on 238 patients (209 men; mean age 74.9 +/- 0.9 years, range 50-94) treated with a Zenith bifurcated graft from 1994 to 1998. The common complications of endoluminal AAA repair (endoleak, migration, graft occlusion, graft kinking, conversion, and deployment failure) were analyzed to determine any associations with selection criteria. RESULTS: By 1998, 69% of endograft patients did not meet the recommended guidelines; however, primary and secondary aneurysm exclusion rates were 87% and 94%, respectively. Over a median follow-up of 13.4 months (interquartile range 2.8-24.0), 38 (16%) patients developed 28 (74%) early and 10 (26%) late type-I endoleaks. The endoleak rate in necks < or = 10 mm long was 57% (8/14). Endoleak was associated with a neck contour change >3 mm (p = 0.003) and neck length <20 mm (p = 0.045). The risk of proximal endoleak was 4 times greater if at least one of the proximal neck guidelines was breached; combined guideline deviations of "contour change and large diameter" (p = 0.0004), "contour change and short length" (p = 0.006), "large diameter and short length" (p = 0.01), and "contour change and angle" (p = 0.03) also increased the risk of endoleak. Endograft migration was seen in 10 (4.2%) cases; only neck diameter >28 mm (p = 0.0024) was associated with this complication. CONCLUSIONS: Proximal neck contour, length, and diameter are the most important criteria in terms of endoleak development. Breaching the proximal neck length criterion resulted in a 4-fold increase in endoleak, and combined deviations from the guidelines multiplied the effect. Necks < or = 10 mm long are unsuitable for the standard Zenith graft.

Analytical modeling and numerical simulation of forces in an endoluminal graft.

PURPOSE: To utilize mathematical analysis and computational fluid dynamics (CFD) to investigate the forces acting within the pressurized aorta and upon a stent-graft and how these forces may affect the ongoing performance of the stent-graft. METHODS: Analytical force balance analysis and CFD simulations using the Fluent code were used to mimic blood flow through a bifurcated stent-graft in a person at rest. Steady-state blood flow was assumed in which the inlet pressure approximated the mean blood pressure (100 mm Hg) and the blood flow velocity was an approximation of the peak systolic flow rate (0.6 m/s). Two sizes of endoluminal grafts were analyzed: the larger graft had an inlet diameter of 3 cm and outlet diameters of 1 cm; the smaller graft diameters measured 2.4 cm proximally and 1.2 cm distally. The endografts were studied in 2 configurations: with the limbs straight and with one bent. RESULTS: For the larger graft model, the normal peak blood flow induced a downward force of 7 to 9 N on the bifurcated grafts. Bending one of the limbs of the graft produced a sideways force of 1.3 N. For the smaller endograft, the downward force was in the range of 3.1 to 5.1 N and the sideways force on a curved limb was approximately 1.5 N. The magnitude of the forces given by the analytical formulae and the CFD results agreed to within 2 significant figures. CONCLUSIONS: These results suggest that the downward force on a bifurcated stent-graft, which may exceed the force required to dislodge it when relying on radial attachment alone, is determined mostly by the proximal graft diameter. Curvature of the graft limbs creates an additional sideways force that works to displace the distal limbs of the graft from the iliac arteries.

Carotid arterial stent placement: results and follow-up in 53 patients.

PURPOSE: To describe the results, complications, and follow-up data after stent placement for occlusive internal carotid arterial disease and to compare the results with those in the literature. MATERIALS AND METHODS: Carotid arterial stent placement was attempted in 57 arteries in 53 patients. Thirty-six (68%) of 53 patients were symptomatic. Forty-two (79%) of 53 patients had one to three clinically important comorbidities and were considered at high risk. All patients underwent pre- and postprocedural independent neurologic examinations. Follow-up consisted of serial duplex ultrasonography and clinical assessment. RESULTS: The immediate technical success rate of stent deployment was 97%. Periprocedurally, three (three [5%] of 57 interventions) transient ischemic attacks and three (three [5%] of 57 interventions) minor strokes occurred. Two deaths occurred in the first 30 days (one myocardial infarction, one renal failure). One ipsilateral major stroke occurred 3 weeks after the procedure. The 30-day ipsilateral major stroke and death rate was 5% (three of 57 interventions). At 30 days, one of three patients with minor stroke had mild residual dysphasia. Treatment remained clinically successful in 48 (96%) of 50 patients. The restenosis rate was 4% (two patients). CONCLUSION: Carotid arterial stent placement in a high-risk population has morbidity and mortality rates comparable to those of carotid endarterectomy in a lower risk population. Carotid arterial stent placement can be performed with a low restenosis rate.

Long-term relative survival following surgery for abdominal aortic aneurysm: a review.

BACKGROUND: The literature reporting the long-term survival following surgery for abdominal aortic aneurysm (AAA) tends to be confusing. As a result, many clinicians looking after patients with AAA may be uncertain about the five-year survival of a given patient. This is in marked contrast to the situation for patients with malignant disease. With the current interest in population screening and endoluminal stenting for AAA, an understanding of long-term survival is increasingly important. METHODS: Thirty two publications in the English language over the last 20 years, containing data pertaining to five-year survival following routine elective surgery for AAA in unselected patients, were identified using Medline searches. RESULTS AND CONCLUSIONS: A range of important methodological differences were noted. The mean five-year crude survival was about 70% while the expected survival of a matched population was close to 80%. Survival was further reduced by about 10% in cases with significant coronary heart disease. Age alone is not a predictor of long-term relative survival with octogenarians who survive beyond 30 days surviving longer than an age-matched population.

Initial results of ultrasound screening for aneurysm of the abdominal aorta in Western Australia: relevance for endoluminal treatment of aneurysm disease.

BACKGROUND: Increased life expectancy in men during the last thirty years is largely due to the decrease in mortality from cardiovascular disease in the age group 29--69 yr. This change has resulted in a change in the disease profile of the population with conditions such as aneurysm of the abdominal aorta (AAA) becoming more prevalent. The advent of endoluminal treatment for AAA has encouraged prophylactic intervention and fueled the argument to screen for the disease. The feasibility of inserting an endoluminal graft is dependent on the morphology and growth characteristics of the aneurysm. This study used data from a randomized controlled trial of ultrasound screening for AAA in men aged 65--83 yr in Western Australia for the purpose of determining the norms of the living anatomy in the pressurized infrarenal aorta. AIMS: To examine (1) the diameters of the infra-renal aorta in aneurysmal and non-aneurysmal cases, (2) the implications for treatment modalities, with particular reference to endoluminal grafting, which is most dependent on normal and aneurysmal morphology, and (3) any evidence to support the notion that northern Europeans are predisposed to aneurysmal disease. METHODS: Using ultrasound, a randomized control trial was established in Western Australia to assess the value of a screening program in males aged 65--83 yr. The infra-renal aorta was defined as aneurysmal if the maximum diameter was 30 mm or more. Aortic diameter was modelled both as a continuous (in mm) and as a binary outcome variable, for those men who had an infra-renal diameter of 30 mm or more. ANOVA and linear regression were used for modelling aortic diameter as a continuum, while chi-square analysis and logistic regression were used in comparing men with and without the diagnosis of AAA. FINDINGS: By December 1998, of 19,583 men had been invited to undergo ultrasound screening for AAA, 12,203 accepted the invitation (corrected response fraction 70.8%). The prevalence of AAA increased with age from 4.8% at 65 yr to 10.8% at 80 yr (chi(2)=77.9, df=3, P<0.001). The median (IQR) diameter for the non-aneurysmal group was 21.4 mm (3.3 mm) and there was an increase (chi(2)=76.0, df=1, P<0.001) in the diameter of the infra-renal aorta with age. Since 27 mm is the 95th centile for the non-aneurysmal infra-renal aorta, a diameter of 30 mm or more is justified as defining an aneurysm. The risk of AAA was higher in men of Australian (OR=1.0) and northern European origin (OR=1.0, 95%CL: 0.9, 1.2) compared with those of Mediterranean origin (OR=0.5, 95%CL: 0.4, 0.7). CONCLUSION: Although screening has not yet been shown to reduce mortality from AAA, these population-based data assist the understanding of aneurysmal disease and the further development and use of endoluminal grafts for this condition.

Intramuscular haemangiomas: hookwire localization prior to surgical excision: report of four cases.

BACKGROUND: Haemangiomas of skeletal muscle are a rare entity, although they are still noted to be one of the most common deep tissue tumours of the lower limb. All such lesions are benign with no recorded evidence of metastasis; but they are associated with a 17-20% local recurrence rate which is thought to be related to inadequate primary surgical excision rather than histological subtype. METHODS: The present case series briefly discusses the pathophysiology, clinical manifestations, diagnostics, differential diagnosis and treatment modalities of intramuscular haemangiomas. The article then focuses on the recent introduction of ultrasound-guided hook-wire localization, which has enabled a great increase in complete surgical excision, resulting in much lower rates of local recurrence and a more pleasing functional and cosmetic result because unnecessary dissection is avoided. RESULTS: Preoperative ultrasound-guided hookwire localization of deep and often non-palpable intramuscular haemangiomas was very helpful in enabling a more complete surgical excision to be carried out. CONCLUSION: Hookwire localization using ultrasound guidance is an invaluable tool in directing the surgeon intraoperatively when excising deep intramuscular haemangiomas.

An update of the Zenith endovascular graft for abdominal aortic aneurysms: initial implantation and mid-term follow-up data.

PURPOSE: To evaluate the initial and mid-term results of the Zenith endovascular grafting system for infrarenal abdominal aortic aneurysms. METHODS: Prospective databases at seven centers were used to assess a cohort of patients that underwent treatment for aortic, aortoiliac, or iliac aneurysms since 1995. Data were analyzed to yield descriptive characteristics that pertained to the patients, the aortic morphologic features, the graft configuration, and the complications. Follow-up imaging data were used to determine size changes of the aneurysm sac, endoleak rates, and further complications. Finally survival data were expressed with a Kaplan-Meier analysis. RESULTS: A total of 528 patients were treated with the Zenith endograft. Most of the patients (66%) were considered to be at a high physiologic risk for open repair. Successful graft implantation was accomplished in all but four patients. An overall endoleak rate of 15% was noted, of which 4% was treated urgently because they were thought to represent attachment site faults. The mean follow-up period was 18 months. A total of eight endograft migrations were detected after 2 years of follow-up with an early version of the system. There were three late conversions; two ruptures occurred during the follow-up period. CONCLUSION: This early and mid-term data support the use of the Zenith endovascular graft for the treatment of aortic and aortoiliac aneurysms in properly selected patients. The risks of significant complications or aneurysm rupture are low.

Fenestration in endovascular grafts for aortic aneurysm repair: new horizons for preserving blood flow in branch vessels.

PURPOSE: To describe techniques for deploying fenestrated stent-grafts that use partial graft deployment and guided tracking of the fenestration to the arterial orifice. TECHNIQUE: Fenestrations have been added to custom-made tube grafts and commercially manufactured Zenith stent-graft systems to preserve perfusion of aortic side branches. Partial device deployment, orientation markers on the endograft, and intraoperative angiography enable maneuvering of the fenestration over the orifice of the target vessel with the aid of guiding catheters. Placement of a Palmaz stent overlapping the fenestration and vessel orifice secures the junction. Two variations of fenestration have preserved blood flow in renal arteries during endovascular repair of abdominal aortic aneurysms (AAAs); similar techniques have maintained flow to the celiac axis in a thoracic aortic aneurysm. CONCLUSIONS: Accurate placement of a fenestration over the orifice of a target vessel is feasible, but long-term maintenance of position is dependent on secure graft fixation. This capability brings us a step closer to overcoming the problem of inadequate necks in infra-renal AAAs, especially when the neck is foreshortened by asymmetry of the renal origins. It may also pave the way for the eventual replacement of the entire aorta with an endoluminal graft.

Screening for abdominal aortic aneurysm: lessons from a population-based study.

OBJECTIVES: To test the acceptability of screening and to identify modifiable risk factors for abdominal aortic aneurysm (AAA) in men. DESIGN: A trial of ultrasound screening for AAA in a population-based random sample of men aged 65-83 years, and a cross-sectional case-control comparison of men in the same sample. PARTICIPANTS: 12,203 men who had an ultrasound examination of their abdominal aorta, and completed a questionnaire covering demographic, behavioural and medical factors. MAIN OUTCOME MEASURES: Prevalence of AAA, and independent associations of AAA with demographic, medical and lifestyle factors. RESULTS: Invitations to screening produced a corrected response of 70.5%. The prevalence of AAAs (> 30 mm) rose from 4.8% in men aged 65-69 years to 10.8% in those aged 80-83 years. The overall prevalence of large (> 50 mm) aneurysms was 0.69%. In a multivariate logistic model Mediterranean-born men had a 40% lower risk of AAA (> 30 mm) compared with men born in Australia (odds ratio [OR], 0.6; 95% CI, 0.4-0.8), while ex-smokers had a significantly increased risk of AAA (OR, 2.3; 95% CI, 1.9-2.8), and current smokers had even higher risks. AAA was significantly associated with established coronary and peripheral arterial disease and a waist:hip ratio greater than 0.9; men who regularly undertook vigorous exercise had a lower risk (OR, 0.8; 95% CI, 0.7-1.0). CONCLUSION: Ultrasound screening for AAA is acceptable to men in the likely target population. AAA shares some but not all of the risk factors for occlusive vascular disease, but the scope for primary prevention of AAA in later life is limited.

The influence of gender on outcome following peripheral vascular surgery: a review.

There is considerable evidence that outcome following intervention for coronary artery disease in women may be worse than it is for men. The influence of gender on outcome following peripheral vascular surgery has received less attention and is the subject of this review. The incidence of most vascular procedures in women is 20-40% that of men. Women appear to have a greater risk of dying following surgery for abdominal aortic aneurysm, a higher risk of stroke and death following carotid endarterectomy, and poorer patency rates following infrainguinal bypass. The causes may include delayed diagnosis and referral, increased co-morbidity and possibly the effect of smaller arteries in women.

Influence of gender on outcome from ruptured abdominal aortic aneurysm.

BACKGROUND: The aim of the present study was to compare outcomes following ruptured abdominal aortic aneurysm (AAA) in men and women. METHODS: Overall mortality from ruptured AAA was compared in men and women using the Western Australia Health Services Research Database. The linked chains of de-identified hospital morbidity and death records were selected using the ICD-9-CM (International Classification of Diseases - Clinical Modification) diagnostic and procedure codes pertaining to AAA. Cases were divided into three groups for analysis: patients who died without admission to hospital, those admitted to hospital with a ruptured AAA but who did not undergo operation, and patients who underwent operation for ruptured AAA. RESULTS: Ruptured AAA occurred in 648 men and 225 women over the age of 55 years during the decade 1985-1994. Only 50 per cent of women, compared with 59 per cent of men, were admitted to hospital. Of those admitted to hospital only 37 per cent of women underwent operation, compared with 63 per cent of men. The overall mortality rate from ruptured AAA was 90 per cent in women and 76 per cent in men (chi2 = 50.34, 1 d.f., P < 0.0001). Although women were, on average, 6 years older than men, this unfavourable pattern occurred across all age groups. CONCLUSION: Women with a ruptured AAA are more likely to die than men. More research is required to identify the causes of this sex difference.

Hybrid open-endoluminal technique for repair of thoracoabdominal aneurysm involving the celiac axis.

PURPOSE: To describe a technique combining endoluminal and open approaches for the repair of thoracoabdominal aneurysms involving the celiac axis. CASE REPORT: Two patients with type I thoracoabdominal aneurysm and suboptimal cardiac reserve underwent transluminal stent-graft implantation. To achieve satisfactory distal seal, the caudal end of the endograft was circumscribed with a Dacron band that was sutured to the aorta and endograft through a midline incision. The patent celiac artery in both patients was ligated to stop retrograde filling of the aneurysm sac. The patients developed no problems perioperatively, and exclusion of the aneurysms was confirmed by follow-up imaging. Three years after endografting, both patients had excluded aneurysms without evidence of endoleak or device migration. CONCLUSIONS: This combined approach is another treatment option for thoracic aneurysms that have an anatomically suitable proximal attachment zone with a compromised distal neck.