Jafar Golzarian

Long-Term Outcome following Stent Reconstruction of the Aortic Bifurcation and the Role of Geometric Determinants

We assessed the long-term patency of kissing stent reconstruction of the aortoiliac bifurcation and identified variables that may influence it. We retrospectively reviewed our experience with stent-reconstruction procedures of the aortoiliac bifurcation from January 1998 through June 2005. The impact of demographic variables, vascular risk factors, disease location and characteristics, stent material and design, and stenting configuration on stent patency was assessed using univariate and multivariate analysis. In particular, we evaluated the effect of geometric mismatch between the protruding segment of the stents and the distal aortic lumen. Sixty-six patients underwent aortobi-iliac stent reconstruction. Indications were bifurcation or bilateral proximal iliac disease in 52 patients and unilateral ostial disease requiring contralateral protection in 14 patients. Limited disease (TASC A and B) was present in 40 limbs in 19 patients; extensive/diffuse disease (TASC C and D) was present in 78 limbs in 47 patients. Complete occlusions were present in 37 limbs in 28 patients (bilateral in nine patients). Self-expanding stents were used in 56 procedures and balloon-expandable stents in 10. Crossing configuration was used in 43 procedures, while abutting configuration was used in 23 procedures. Technical success was achieved in 62 patients (94%), with all four failures due to inability to cross a chronically occluded limb. Three of these patients underwent aortomono-iliac stenting with a crossover femoral-femoral bypass graft, with the remaining one opting for no further interventions. Median combined follow-up was 37 +/- 27 months (range 0-102). Hemodynamically significant restenosis developed in nine patients (14%). The management of restenosis was endovascular in eight patients and was successful in all (balloon dilation in four, restenting in three, thrombolysis and stenting in one) and operative in one patient who developed aortic occlusion and underwent aortobifemoral grafting. Survival table analysis showed primary and assisted patency rates at 4 years of 81% and 94%, respectively. The mortality rate during follow-up was 19 (cardiac cause in eight, pulmonary cause in three, and malignancy in five). Univariate analysis showed radial mismatch (aortic lumen dead space around the protruding segment of the stents), female gender, prior occlusion, and residual stenosis to be significant predictors of restenosis. Multivariate logistic regression analysis showed radial mismatch to be the only significant determinant of restenosis, although the statistical power of the model was limited by the small number of restenoses. Stent reconstruction of the aortoiliac bifurcation for occlusive disease is effective and durable, even with complex aortoiliac disease and long segment occlusions. Most restenoses are amenable to endovascular treatment, with excellent long-term assisted patency. Geometric variables related to individual aortic anatomy and disease pattern (patient-dependent) and stenting configuration (operator-dependent) may have an impact on long-term patency.

Endoleakage after endovascular treatment of abdominal aortic aneurysms: diagnosis, significance and treatment

Endoleak, also called leakage, leak and Perigraft leak, is a major complication and its persistence represents a failure of endovascular aortic aneurysm repair. Its detection and treatment is therefore of primary importance, since endoleak can be associated with pressurization (increase in pressure) of the sac, resulting in expansion and rupture of the aneurysm. The aim of this paper is to discuss the definition, significance, diagnosis and different options to treat endoleak.

Nonvariceal upper gastrointestinal bleeding

Nonvariceal upper gastrointestinal bleeding (NUGB) remains a major medical problem even after advances in medical therapy with gastric acid suppression and cyclooxygenase (COX-2) inhibitors. Although the incidence of upper gastrointestinal bleeding presenting to the emergency room has slightly decreased, similar decreases in overall mortality and rebleeding rate have not been experienced over the last few decades. Many causes of upper gastrointestinal bleeding have been identified and will be reviewed. Endoscopic, radiographic and angiographic modalities continue to form the basis of the diagnosis of upper gastrointestinal bleeding with new research in the field of CT angiography to diagnose gastrointestinal bleeding. Endoscopic and angiographic treatment modalities will be highlighted, emphasizing a multi-modality treatment plan for upper gastrointestinal bleeding.

Higher Rate of Partial Devascularization and Clinical Failure After Uterine Artery Embolization for Fibroids with Spherical Polyvinyl Alcohol

Jafar Golzarian, Elvira Lang, David Hovsepian, Thomas Kroncke, Leo Lampmann, Paul Lohle, Jean-Pierre Pelage, Richard Shlansky-Goldberg, David Valenti, Dierk Vorwerk, James Spies Department of Radiology, 200 Hawkins Drive, 3957 JPP, University of Iowa, Iowa City, Iowa 52242, USA Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA Mallinckrodt Institute, St. Louis, MO 63110, USA Department of Radiology, University Clinic Charit/, Berlin 10117, Germany Department of Radiology, St. Elisabeth Hospital, AN Tilburg 5032, The Netherlands Department of Radiology, Hopital Ambroise Pare, Boulogne 92104 cedex, France University of Pennsylvania Medical Center, Philadelphia, PA 19104, USA Royal Victoria Hospital, McGill University, Montreal, H3A 1A1 Quebec, Canada Department of Diagnosis and Imaging, Klinikum Ingolstadt, Ingolstadt 85049, Germany Georgetown University Medical Center, Washington, DC 20007, USA

Role of graft oversizing in the fixation strength of barbed endovascular grafts

PURPOSEnThe role of endovascular graft oversizing on risk of distal graft migration following endovascular aneurysm repair for abdominal aortic aneurysm is poorly understood. A controlled in vitro investigation of the role of oversizing in graft-aorta attachment strength for endovascular grafts (EVGs) with barbs was performed.nnnMETHODSnBarbed stent grafts (N = 20) with controlled graft oversizing varying from 4-45% were fabricated while maintaining other design variables unchanged. A flow loop with physiological flow characteristics and a biosynthetic aortic aneurysm phantom (synthetic aneurysm model with a bovine aortic neck) were developed. The stent grafts were deployed into the aortic neck of the bio-synthetic aortic aneurysm phantom under realistic flow conditions. Computed tomography imaging of the graft-aorta complex was used to document attachment characteristics such as graft apposition, number of barbs penetrated, and penetration depth and angle. The strength of graft attachment to the aortic neck was assessed using mechanical pullout testing. Stent grafts were categorized into four groups based on oversizing: 4-10%; 11-20%; 21-30%; and greater than 30% oversizing.nnnRESULTSnPullout force, a measure of post-deployment fixation strength was not different between 4-10% (6.23 +/- 1.90 N), 11-20% (6.25 +/- 1.84 N) and 20-30% (5.85 +/- 1.89 N) groups, but significantly lower for the group with greater than 30% oversizing (3.67 +/- 1.41 N). Increasing oversizing caused a proportional decrease in the number of barbs penetrating the aortic wall (correlation = -0.83). Of the 14 barbs available in the stent graft, 89% of the barbs (12.5 of 14 on average) penetrated the aortic wall in the 4-10% oversizing group while only 38% (5.25 of 14) did for the greater than 30% group (P < .001). Also, the stent grafts with greater than 30% oversizing showed significantly poorer apposition characteristics such as eccentric compression or folding of the graft perimeter. The number and depth of barb penetration were found to be positively correlated to pullout force.nnnCONCLUSIONnGreater than 30% graft oversizing affects both barb penetration and graft apposition adversely resulting in a low pullout force in this in vitro model. Barbed stent grafts with excessive oversizing are likely to result in poor fixation and increased risk of migration.

Bolus characteristics based on Magnetic Resonance Angiography

BackgroundA detailed contrast bolus propagation model is essential for optimizing bolus-chasing Computed Tomography Angiography (CTA). Bolus characteristics were studied using bolus-timing datasets from Magnetic Resonance Angiography (MRA) for adaptive controller design and validation.MethodsMRA bolus-timing datasets of the aorta in thirty patients were analyzed by a program developed with MATLAB. Bolus characteristics, such as peak position, dispersion and bolus velocity, were studied. The bolus profile was fit to a convolution function, which would serve as a mathematical model of bolus propagation in future controller design.ResultsThe maximum speed of the bolus in the aorta ranged from 5–13 cm/s and the dwell time ranged from 7–13 seconds. Bolus characteristics were well described by the proposed propagation model, which included the exact functional relationships between the parameters and aortic location.ConclusionThe convolution function describes bolus dynamics reasonably well and could be used to implement the adaptive controller design.

Interventional Management of Postpartum Hemorrhage

The selective transcatheter technique for embolization of uterine and/or internal iliac arteries in the management of intractable bleeding after delivery is safe and effective. In order to create the best hemodynamic and clinical conditions for this therapy, a strong multidisciplinary collaboration is essential to optimize clinical outcomes.

Projection-based bolus detection for computed tomographic angiography

Abstract: Computed tomographic (CT) angiography is important for imaging studies on cardiovascular structures, peripheral vessels, and solid organs. In practice, a CT angiography scan is triggered by the bolus arrival at a prespecified anatomical location, which is determined using CT fluoroscopy. In this article, we propose a projection-based method adapted from the Grangeat formula to detect the bolus arrival. Then, we evaluate our new method in numerical and animal studies. Our results indicate that this method allows significantly better temporal resolution and is computationally more efficient, as compared with the image-based methods.

The Effect of Aortic Endovascular Graft Oversizing on Barb Penetration and Fixation Strength

Endovascular repair of abdominal aortic aneurysm (AAA), where an endovascular graft (EVG) — a stented vascular graft — is implanted intraluminally into the AAA has shown excellent short term outcome. However, long term outcome of implanted EVGs is fraught with new complications, the most severe of which is endoleak from graft migration, which can lead to re-pressurization of the AAA and potentially rupture. Graft migration is defined as the distal drift of an implanted EVG of 5mm or more from its initial anchor site (Figure 1). There have been many design changes to help decrease the rate of EVG migration including the addition of proximal attachment barbs to grafts to help secure them to the aortic wall. However, studies show that freedom from migration rates have not significantly increased for those grafts containing barbs compared to grafts without barbs [1]. We believe that controlled studies of endovascular graft parameters can lead to improvements in its design that increase graft attachment strength and hence decrease the risk of migration. The aim of the current study was to assess a key design variable in barbed grafts namely, graft oversizing (GO), defined as the ratio of expanded graft dia to aorta dia. We sought to assess the relationship between GO and attachment strength in barbed EVGs. Specifically, we hypothesized that a high GO will impede the ability of the EVG barbs to effectively penetrate the aortic wall.© 2008 ASME

Endoleak: Definition, Diagnosis, and Management

It seems certain that EVAR will continue to be a primary treatment for many years. Endoleak is an ongoing problem associated with EVAR. Imaging plays a critical role in detecting endoleak. CTA is the first line diagnostic modality. Optimal CTA protocol needs to include a delayed acquisition. There are many endovascular options available for treatment of persistent endoleaks. The optimal treatment depends on the type of the endoleak.