Biomedical subjects

J D Blankensteijn

Publications and source records attributed to J D Blankensteijn.

At least 19 recordsLinked to original sources

PubMed2003

[Treatment of abdominal aortic aneurysms].

Three treatment options are available for an asymptomatic abdominal aortic aneurysm (AAA): an expectant approach with ultrasonographic check-ups, reconstruction of the abdominal aorta via the conventional ('open') approach and endovascular repair. For aneurysms less than 5.5 cm in diameter the annual rupture risk is less than 1%. For these patients a better alternative to the expectant approach does not seem to exist. The risk of rupture needs to be weighed up against the risks of a conventional operation. The operation mortality of patients with a non-ruptured AAA is about 7% while other serious complications occur in about 10%. The short to medium-term results of endovascular aneurysm repair are characterized by high reintervention rates, material fatigue and device failure. The three treatment options described are currently being investigated in several large-scale randomised studies for AAAs greater than 5.5 cm in diameter.

Aorta, Abdominal↗

PubMed2003

Rapid, arteriovenous graft failure due to intimal hyperplasia: a porcine, bilateral, carotid arteriovenous graft model.

BACKGROUND: The loss of patency constitutes the major complication of arteriovenous (AV) polytetrafluoroethylene hemodialysis grafts. In most cases, this graft failure is due to intimal hyperplasia at the venous outflow tract, including proliferation of vascular, smooth muscle cells and fibroblasts with deposition of extracellular matrix proteins. Thus far, procedures developed for improving patency have proven unsuccessful, which can be partly explained by the lack of relevant animal models. For this purpose, we developed a porcine model for AV graft failure that will allow the assessment of promising therapeutic strategies in the near future. MATERIALS AND METHODS: In 14 pigs, AV grafts were created bilaterally between the carotid artery and the jugular vein using expanded polytetrafluoroethylene. Two, 4 or 8 weeks after AV shunting, the grafts and adjacent vessels were excised and underwent histologic analysis. RESULTS: From 2 weeks onwards, a thick neo-intima developed at the venous anastomosis, predominantly consisting of alpha-actin-positive vascular smooth muscle cells (VSMC). Intimal area increased over time, coinciding with a decreased graft flow. Grafts remained patent for at least 4 weeks. At 8 weeks, patency rates declined to less than 50% due to thrombus formation superimposed on progressive neo-intima formation. CONCLUSIONS: Implantation of an AV graft between the carotid artery and jugular vein in pigs causes a rapid neo-intimal response, accompanied by a loss of patency of 50% at 8 weeks after surgery. This model offers a suitable tool to study local interventions aimed at the improvement of AV graft patency rates.

Animals↗

PubMed2003

Screening for asymptomatic internal carotid artery stenosis and aneurysm of the abdominal aorta: comparing the yield between patients with manifest atherosclerosis and patients with risk factors for atherosclerosis only.

OBJECTIVE: The purpose of this study was to investigate whether screening for internal carotid artery stenosis (ICAS) and aneurysm of the abdominal aorta (AAA) is indicated in patients with either manifest atherosclerotic disease or with only risk factors for atherosclerosis. STUDY DESIGN: Data were obtained for 2274 patients enrolled in the SMART study, an ongoing single-center, prospective cohort study of patients referred to our vascular center with manifest atherosclerotic disease (peripheral atherosclerotic disease [PAD]; transient ischemic attack [TIA], stroke, or ICAS; AAA; angina pectoris; or myocardial infarction [MI]) or with only risk factors for atherosclerosis (diabetes mellitus, hypertension, hyperlipidemia). The presence of ICAS or AAA was determined with duplex scanning and ultrasonography. RESULTS: The prevalence of ICAS 70% or greater is low in patients with risk factors for atherosclerosis only (1.8%-2.3%), intermediate in patients with angina pectoris or MI (3.1%), and highest in patients with PAD (12.5%) or AAA (8.8%). The prevalence of AAA 3 cm or larger is low in patients with risk factors for atherosclerosis only (0.4-1.6%), intermediate in patients with angina pectoris or MI (2.6%), and highest in patients with PAD (6.5%) or TIA, stroke, or ICAS (6.5%). The prevalence of AAA larger than 5 cm is low in all of the considered patient groups. The yield of screening can be optimized through selection on the basis of simple patient characteristics. In patients with PAD, selecting those with advanced age (>54 years) increased the prevalence of ICAS to 21.8%. Selecting patients with lower diastolic blood pressure (<83 mm Hg) increased the prevalence of ICAS to 17.9%. In patients with both advanced age and lower diastolic blood pressure, the prevalence of ICAS increased to 34.7%. Selecting patients with advanced age increased the prevalence of AAA 3 cm or larger to 9.6%. In patients with TIA, stroke, or ICAS, selecting those with advanced age increased the prevalence of AAA 3 cm or larger to 8.2%. Selecting patients with taller stature (>169 cm) increased the prevalence of AAA 3 cm or larger to 9.3%. In patients with advanced age and taller stature, the prevalence of AAA 3 cm or larger increased to 13.1%. CONCLUSIONS: Screening for ICAS should be limited to patients referred with PAD or AAA, especially those with advanced age or with low diastolic blood pressure. Screening for AAA should be limited to patients referred with PAD or with TIA, stroke, or ICAS, particularly those with advanced age or tall stature. In patients referred with angina pectoris or MI and those referred with only risk factors for atherosclerosis, screening cannot be endorsed.

Adult↗

PubMed2003

Decision-making in follow-up after endovascular aneurysm repair based on diameter and volume measurements: a blinded comparison.

OBJECTIVE: to assess whether volume, in addition to diameter, measurements facilitate decision-making after endovascular aneurysm repair (EVAR). MATERIAL/METHODS: patients (n = 82) with an immediately post-EVAR, and at least one follow-up (3-60 months), computed tomographic angiogram (CTA) were studied. The actual and all preceding proportional sac size changes were recorded. The resulting 347 diameter and 347 volume data were placed in random order and reviewed by three blinded observers who then recommended one of three treatment policies: "good/wait", "uncertain/intensify follow-up" or "not good/further diagnostics (Dx) or intervention (Rx)". The observers were instructed to consider changes of 10% relevant. One observer reviewed the graphs twice. RESULTS: the interobserver agreements (kappa) for the diameter were 0.92, 0.81 and 0.76 and for volumes 0.91, 0.88 and 0.86. The intra-observer agreement was 0.93 for both diameter and volume. Volume data resulted in significantly more "good/wait" decisions out to 36 months. Diameter data resulted in more "not good/Dx or Rx"-decisions out to 36 months (all p < 50.005). CONCLUSION: post-EVAR aneurysm sac volume data appears to provide earlier reassurance, reduce unnecessary interventions and to be more sensitive to secondary problems than diameter data alone.

Aneurysm↗

PubMed2002

Contaminants from the transplant contribute to intimal hyperplasia associated with microvascular endothelial cell seeding.

OBJECTIVES: seeding prosthetic grafts with fat-derived microvascular endothelial cells (MVEC) results not only in a non-thrombogenic EC layer, but also in intimal hyperplasia. Here we investigated incidence, composition, progression, and cause of this intimal hyperplasia. DESIGN: EPTFE grafts with MVEC were implanted as carotid interpositions in six dogs with 1 month, and in three dogs with 4, 8 and 12 months follow-up. Grafts seeded without cells, implanted in the contralateral carotid, served as a control. In another three dogs labelled cells were seeded to investigate the contribution of the seeded cells (2-3 weeks). MATERIALS AND METHODS: MVEC were isolated from the falciform ligament. Cells were pressure seeded on ePTFE grafts. Labelling was performed using retroviral gene transduction. The grafts were analysed with immunohistochemical techniques. RESULTS: after 1 month, all patent non-seeded grafts (5/6) showed fibrin and platelet deposition, and all patent seeded grafts (5/6) were covered with a confluent endothelial monolayer on top of a multilayer of myofibroblasts, elastin and collagen. After long term follow-up, all non-seeded grafts were occluded, all patent seeded grafts (4 and 12 months) were covered with an EC-layer with intimal hyperplasia underneath. The thickness of the intima did not progress after 1 month. Transduced cells were found in the endothelial monolayer, hyperplastic intima and luminal part of the prosthesis. CONCLUSIONS: MVEC seeding in dogs results in intimal hyperplasia in all patent grafts, which contains myofibroblasts. Contaminants from the transplant contribute to this intimal hyperplasia.

Animals↗

PubMed2002

Reduction of non-endothelial cell contamination of microvascular endothelial cell seeded grafts decreases thrombogenicity and intimal hyperplasia.

INTRODUCTION: fat derived microvascular endothelial cells (MVEC) seeded on prosthetic vascular grafts, improve patency in animals. Results in humans were disappointing, due to thrombogenicity and progressive intimal hyperplasia. Also in animals intimal hyperplasia was found. We postulate that contaminating cells present in the transplant are involved in the intimal hyperplasia. We developed a method to further purify human MVEC from 40-90%. Here we tested the effects of enrichment upon thrombogenicity and seeding-related intimal hyperplasia. METHODS: liposuction fat was enzymatically digested and centrifuged. To enrich MVEC, contaminating macrophages and fibroblasts were removed with dynabeads coated with macrophage- and fibroblast-specific antibodies. Thrombogenicity was assessed by measuring tissue factor and thrombomodulin activity, presence of endothelial nitric oxide synthase and via perfusion of the cells with whole blood. To investigate seeding-related intimal hyperplasia, PTFE grafts were seeded with the cells and cultured for 3 weeks. RESULTS: tissue factor activity of purified cells was reduced compared to nonpurified cells. Purified cells showed thrombomodulin activity and eNOS expression. Fragment 1+2 and Fibrinopeptide A generation after perfusion of purified cells were significantly lower than after perfusion of nonpurified cells, and only nonpurified cells were covered with platelets and fibrin. Prostheses seeded with nonpurified cells showed an EC monolayer above a multilayer of myofibroblasts, prostheses seeded with purified cells only showed a single EC monolayer. Mixing experiments with human umbilical cord EC (HUVEC) and fibroblasts showed that when more than 25% HUVEC were present a confluent EC layer was formed. When the amount of fibroblasts was 25% or less, no development of a subendothelial multilayer of myofibroblasts was found within 3 weeks. CONCLUSION: reduction of non-endothelial cell contamination of microvascular endothelial cell seeded grafts decreases thrombogenicity and might prevent seeding-related intimal hyperplasia.

Cell Separation↗

PubMed2002

The sac shrinking process after EAR does not start immediately in most patients.

OBJECTIVE: the aim of this study was to determine the pattern of shrinkage after endovascular aneurysm repair (EAR) using logarithmic, exponential and linear models and to calculate a lag time is present. PATIENTS AND METHODS: patients with a complete CTA follow-up of 2 years and a primary shrinking aneurysm were included, resulting in a study group of 29 patients. Six functions, logarithmic, exponential and linear, all with and without lag time, were fitted to the thrombus volume obtained from measurements postoperative and after 6, 12 and 24 months. The correlation coefficient was used to determine the association between the calculated and measured values. A correlation coefficient >0.95 was considered a good fit. RESULTS: a logarithmic model produced the best fits. From the 29 patients, two patients could not be described by any model. The remaining 27 patients could be fitted using a logarithmic function with a correlation coefficient of >0.95 (median 0.99, range 0.95-1.00). Twenty-two of these patients had a lag time (median 63.4 days, range 5.8-252.3). Only five of the initial 44 patients (11%) showed immediate sac shrinkage. CONCLUSION: almost all shrinkage processes could be described by a logarithmic function. In over 75% of patients a lag time to shrinkage could be calculated. In only a small proportion did the shrinking process start immediately after EAR.

Aorta, Abdominal↗

PubMed2002

The Dutch Randomised Endovascular Aneurysm Management (DREAM) trial. Background, design and methods.

After the introduction of endovascular repair of abdominal aortic aneurysms (AAA), both benefits and drawbacks of this new technique have been reported. To assess whether the new technique is an adequate substitute of conventional AAA repair, a randomised study is due. The Dutch Randomised Endovascular Aneurysm Management (DREAM) trial is a randomised multicenter trial enrolling patients eligible for elective treatment of infrarenal AAAs. In this study, the cost-effectiveness of endovascular aneurysm repair (EAR) is compared with that of conventional transabdominal surgery, in patients that are considered suitable for both types of treatment. The primary endpoint is combined operative mortality and morbidity. Secondary endpoints and additional assessments include event free survival, quality of life, length of hospital stay and costs. It is expected that the DREAM-trial will lead to a safe and controlled introduction of a new technology. Also, the medical community will obtain valid scientific evidence of the merits of endovascular AAA repair. Finally, policy makers will be provided with accurate cost-effectiveness data for the Dutch healthcare system. The aim of the present paper is to describe the background, methods and design of the DREAM-trial.

Aortic Aneurysm, Abdominal↗

PubMed2001

[Spiral computed tomographic angiography as a substitute for intra-arterial angiography of aorta and its branches].

Until recently, intra-arterial angiography was the diagnostic method of first choice when pathology of the aorta or its branches was suspected. A disadvantage of this technique is that only the lumen of spaces with blood flow can be visualised and that the soft tissue surroundings remain (partly) invisible. Spiral computer tomographic angiography (CTA) has some major advantages compared with conventional angiography. The technique is less invasive and faster. Also, the soft tissue is imaged by CTA. In addition, computer reconstructions allow viewing from all directions without the limitations of overprojection. Spiral CTA is a suitable technique for imaging the thoracic part of the aorta: in case of dissection if transoesophageal echography is not available, in case of an aneurysm to determine the diameter and in case of rupture as a highly sensitive but not very specific examination technique. For imaging of the abdominal part of the aorta, spiral CTA may be considered. In case of an aneurysm or a possible rupture of this part of the aorta it is then possible to visualize the operation area and to choose the optimal approach. For the exclusion of stenoses in mesenteric arteries or in renal arteries, spiral CTA offers the advantage of non-invasivity. The technique is less suitable for demonstration of these stenoses and does not allow immediate intervention.

Adult↗

PubMed2001

Cerebral blood flow in relation to contralateral carotid disease, an MRA and TCD study.

OBJECTIVE: to describe redistribution of cerebral blood flow in patients with severe internal carotid artery (ICA) stenoses in relation to contralateral ICA disease. METHODS: sixty-six patients scheduled for carotid endarterectomy (CEA) were grouped according to severity of contralateral stenosis (<30% [group I]; 30-69% [group II]; 70-99% [group III]; occlusion [group IV]. Transcranial Doppler (TCD) and magnetic resonance angiography (MRA) investigations were performed preoperatively. RESULTS: TCD demonstrated a reversed flow in the contralateral anterior cerebral artery (A(1)segment) and ophthalmic artery in three-quarters of group IV patients (p <0.0001). Group IV patients also exhibited decreased blood flow velocity in the contralateral middle cerebral artery (p =0.001). MRA showed increased ipsilateral ICA and basilar artery (BA) blood flow volumes (Q-flows) in group IV patients when compared to the other groups (p <0.001). No changes in total Q-flow (ICAs+BA) were found. CONCLUSIONS: in patients considered for CEA, the severity of the contralateral ICA disease is an important determinant of the pattern of blood flow redistribution through the anterior communicating pathway and ophthalmic artery. Significant flow redistribution through the posterior communicating pathway occurs especially in patients with contralateral ICA occlusion.

Adult↗

PubMed2001

Concerns for the durability of the proximal abdominal aortic aneurysm endograft fixation from a 2-year and 3-year longitudinal computed tomography angiography study.

OBJECTIVE: To provide a long-term perspective on the durability of the proximal abdominal aortic aneurysm endograft fixation from a single device series with perpendicular neck measurements in two groups of patients with complete 2- and 3-year follow-up. DESIGN: This was a prospective study of postoperative, radiologic images. SETTING: The study used a referral center, institutional practice, and ambulatory patients. SUBJECTS: From January 1994 until May 1998, 37 endografts were implanted for abdominal aortic aneurysm. In the first postoperative year, there were four unrelated deaths and six conversions, leaving 27 patients with complete 24-month data and 13 with complete 36-month data. MAIN OUTCOME MEASURE: Computed tomography angiograms were processed on a work station to measure the neck perpendicular to the central lumen line of the aorta. The surface area at the proximal endovascular anastomosis was recorded at each follow-up interval and related to the postoperative size at the same level. RESULTS: Significant dilatation of the surface area was found: 20% (16% to 27%) at 24 months (c2 = 30; P < .001, Friedman) and 23% (18% to 28%) at 36 months (c2 = 27; P < .001, Friedman). This increase in neck size was continuous and linear, with a yearly rate of approximately 10% surface area; translated into diameter, this approximates 1 mm/y. CONCLUSION: A continuous aortic enlargement of approximately 1 mm/y at the level of the proximal endovascular anastomosis was found. Because of the practice of oversizing the endograft relative to the infrarenal aortic neck, a loss of the endovascular seal may not become apparent until several years after endovascular abdominal aortic aneurysm repair is performed.

Aged↗

PubMed2000

Early experience with intravascular ultrasound in evaluating the effect of statins on femoropopliteal arterial disease: hypothesis-generating observations in humans.

The purpose of this study was to compare the vascular response seen with intravascular ultrasound (IVUS) at 1-year follow-up between statin-treated and non-statin-treated patients. Patients (n = 10) undergoing percutaneous transluminal angioplasty (PTA) of the femoropopliteal artery were studied with IVUS immediately after PTA and at 1-year follow-up. In nondilated matched vascular segments, the change in lumen, vessel, and plaque volume was assessed. In balloon-dilated matched vascular segments, the change in lumen, vessel, and plaque area was assessed. A comparison was made between statintreated (n = 5) and non-statin-treated patients (n = 5) in lumen, vessel, and plaque changes. At follow-up, both statin-treated and non-statin-treated patients showed a similar increase in plaque volume at the nondilated segment (+4% and +2%, respectively). In statin-treated patients the plaque volume increase was compensated by an increase in vessel volume (+2%), resulting in an increase in lumen volume (+1%). In non-statin-treated patients, on the other hand, the increase in plaque volume was associated with a decrease in vessel volume (-2%), resulting in a decrease in lumen volume (-4%). At the balloon-dilated segment a similar trend in changes of lumen, vessel, and plaque was encountered. Differences between both groups of patients were not statistically significant. Despite the nonsignificant nature of the observation, this small retrospective IVUS study may generate the hypothesis that statin therapy may contribute to superior long-term lumen dimensions by inducing positive vascular remodeling both in nondilated and balloon-dilated vascular segments.

Adult↗

PubMed2000

Dilatation of the proximal neck of infrarenal aortic aneurysms after endovascular AAA repair.

OBJECTIVES: to assess size changes of the proximal aortic neck after endograft placement. METHODS: since 1994, 54 consecutive patients have undergone abdominal aortic aneurysm (AAA) repair with the Endovascular Technologies (EVT) endograft. The study group comprised the 33 patients who had completed at least six months of the prospective follow-up protocol. The pre-, postoperative and follow-up helical computed tomography (CT) angiograms (CTAs) were processed on a workstation. The proximal neck dimensions were measured perpendicular to the central lumen line of the aortic neck. The cross-sectional area was measured at the proximal attachment system and at 1 cm proximal to the renal arteries. RESULTS: while the dimensions of suprarenal aorta did not change, a significant dilatation of the proximal neck was found. The median increase was 10.3% at 6 months and 15.5% at 12 months. No correlation could be found between the amount of dilatation and pre- or postoperative neck-size, graft diameter and amount of graft-oversizing. CONCLUSION: the infrarenal aortic neck demonstrates continued dilatation during follow-up after endograft placement.

Aged↗

PubMed2000

Maximal aneurysm diameter follow-up is inadequate after endovascular abdominal aortic aneurysm repair.

BACKGROUND: follow-up after endovascular abdominal aortic aneurysm repair (EAR) generally consists of serial diameter measurements. A size change after EAR, however, is the consequence of alterations of the excluded aneurysm sac volume. OBJECTIVE: to assess the agreement between diameter measurements and volume measurements after endovascular aneurysm repair. PATIENTS AND METHODS: from 53 consecutive patients scheduled for EAR, follow-up of at least 6 months was available in 35 patients. CTA was performed on all patients at discharge, at 6 months and yearly thereafter. The resulting 113 datasets were processed on a workstation in a blinded and random order. Maximal aneurysm diameter (DMAX) was measured along the central lumen line. Total aneurysm volume was measured by manual segmentation. All measurements of an individual patient were compared with each other, resulting in 149 comparisons. The significance of individual size changes was classified based on the 95% confidence limits of the intra-observer variability, using difference-of-means analysis. DMAX changes were compared to volume changes. RESULTS: in 37% of the comparisons, discordance was found between DMAX and volume measurements. A decrease in aneurysm size was missed using DMAX in 14% of cases and an increase in 19% of cases. CONCLUSION: aneurysm size changes after EAR are not noticed using maximal diameter measurements in over one-third of cases.

Aftercare↗

PubMed2000

Preoperative MRA flow quantification in CEA patients: flow differences between patients who develop cerebral ischemia and patients who do not develop cerebral ischemia during cross-clamping of the carotid artery.

BACKGROUND AND PURPOSE: We sought to investigate whether preoperative volume flow in the internal carotid arteries (ICAs), the basilar artery (BA), and the middle cerebral arteries (MCAs) and collateral flow via the circle of Willis differ between patients who do and patients who do not develop cerebral ischemia during clamping of the carotid artery in carotid endarterectomy (CEA). METHODS: Quantitative volume flow in the ICAs, BA, and MCAs and directional flow in the circle of Willis were measured preoperatively with 2-dimensional phase-contrast MR angiography in 86 CEA patients. During the operation, electroencephalographic (EEG) recordings were obtained that were monitored by a clinical neurophysiologist. Reference volume flow values were assessed in 24 control subjects. RESULTS: In patients with an ICA stenosis without contralateral ICA occlusion (n=62), of whom 16% developed ischemic EEG changes during clamping, preoperative flow in the clamped ICA was significantly higher in patients with cerebral ischemia than in patients without (mean, 278 versus 160 mL/min; P:<0.05). Flow in the contralateral ICA (156 versus 273 mL/min; P:<0.01), flow in the BA (116 versus 165 mL/min; P:<0.05), and presence of collateral flow via the circle of Willis to the clamped ICA (0% versus 37%; P:<0.05) were significantly lower. MCA flow did not differ significantly between groups. Additionally, in patients with an ICA stenosis and a contralateral ICA occlusion (n=24), of whom 42% developed cerebral ischemia, preoperative flow in the clamped ICA was significantly higher in patients with cerebral ischemia than in patients without (309 versus 239 mL/min; P:<0.05). BA flow, MCA flow, and presence of willisian collateral flow (0% versus 14%) did not differ significantly between groups. CONCLUSIONS: Preoperative volume flow in the clamped ICA is significantly higher in CEA patients with ischemic EEG changes during clamping than in CEA patients without such changes. The latter patients probably have better developed collateral pathways preoperatively.

Aged↗

PubMed2000

Three-dimensional intravascular ultrasound assessment of abdominal aortic aneurysm necks.

PURPOSE: To document the accuracy of an automated analysis system for measuring lumen diameter and neck lengths of abdominal aortic aneurysms (AAAs) from intravascular ultrasound (IVUS) images and to describe additional features associated with 3-dimensional (3D) IVUS imaging. METHODS: Twenty-two aortic aneurysms were studied with IVUS. Lumen diameters obtained using the automated analysis system were compared with manual measurements from axial IVUS scans, as were neck lengths obtained using automated analysis versus those measured with the aid of a displacement sensing device. Automated analyses were repeated by a second observer. Agreement was expressed as the coefficient of variation (CV). RESULTS: Twenty proximal aortic, 6 distal aortic, and 3 iliac necks were available for analysis. Comparison between automated analysis and manual measurements for lumen diameter revealed a difference of 0.45 +/- 0.42 mm (mean +/- SD, Pearson's r = 0.99, p < 0.001, CV = 2.1%) and a difference of 0.05 +/- 0.12 cm (r = 0.99, p = 0.04, CV = 4.1%) for neck length. Interobserver difference for lumen diameter was 0.13 +/- 0.66 mm (r = 0.99, p < 0.001, CV = 3.4%) and 0.05 +/- 0.11 cm for length measurements (r = 0.99, p = 0.02, CV = 3.5%). The 3D IVUS imaging facilitated the identification of neck configuration. CONCLUSIONS: Automated analysis of IVUS images allows accurate measurement of the lumen diameter of proximal and distal AAA necks and gives length measurements comparable to those of manual analysis. Longitudinal display of IVUS images aids in the elucidation of neck anatomy.

Aged↗

PubMed2000

A simple technique to improve the accuracy of proximal AAA endograft deployment.

PURPOSE: To report a technique for overcoming the positioning errors caused by angulation and rotation of the proximal aortic neck when anteroposterior fluoroscopic imaging is used during endograft deployment. TECHNIQUE: Aortic neck angulation and rotation were measured preoperatively using spiral computed tomographic angiography in sagittal and axial projections. Before proximal graft deployment, the proximal end of the endograft was centered in the field of view, and the position of the C-arm was adjusted to the aortic neck angulation. Using this technique, optimal positioning of the endograft relative to the true position of the renal arteries can be achieved. CONCLUSIONS: C-arm angulation and rotation is helpful in facilitating perfect positioning for an optimal seal between the endograft and the infrarenal aortic neck.

Aortic Aneurysm, Abdominal↗

PubMed2000

Inter- and intraobserver variability of CT measurements obtained after endovascular repair of abdominal aortic aneurysms.

OBJECTIVE: Important decisions are made on the basis of CT angiographic measurements of aneurysm size obtained after endovascular abdominal aortic aneurysm repair; however, little is known about the variability of these measurements. We evaluated the variability of CT angiographic measurements of aneurysm size obtained after endovascular abdominal aortic aneurysm repair. MATERIALS AND METHODS: Thirty CT angiographic data sets were randomly chosen from 91 sets, including preoperative, postoperative, and follow-up CT images. All images were obtained according to a standardized acquisition protocol. On a workstation, three parameters were measured: maximum aneurysm diameter, maximum aneurysm cross-sectional area, and aneurysm volume. All data sets were measured twice by two investigators in a random order. The difference of each pair of measurements was plotted against the mean value. The mean difference and its standard deviation were calculated with a repeatability coefficient. RESULTS: The intraobserver repeatability coefficient for observer 1 was 3.8 mm for diameter, 201.7 mm(2) for cross-sectional area, and 5.6 mL for volume. For observer 2, these figures were 3.0 mm, 219.0 mm(2), and 8.1 mL, respectively. The interobserver repeatability coefficients were 3.9 mm, 236.2 mm(2), and 10.3 mL. CONCLUSION: Determination of the repeatability coefficient of aneurysm size measurements obtained after endovascular abdominal aortic aneurysm repair provides a good description of precision.

Aged↗