Publications
252 results found
Xu XY, Kandail H, Hamady M, 2016, Effect of a Flared Renal Stent on the Performance of Fenestrated Stent-Grafts at Rest and Exercise Conditions, Journal of Endovascular Therapy, Vol: 23, Pages: 809-820, ISSN: 1526-6028
Purpose: To quantify the hemodynamic impact of a flared renal stent on the performance of fenestrated stent-grafts (FSGs) by analyzing flow patterns and wall shear stress–derived parameters in flared and nonflared FSGs in different physiologic scenarios. Methods: Hypothetical models of FSGs were created with and without flaring of the proximal portion of the renal stent. Flared FSGs with different dilation angles and protrusion lengths were examined, as well as a nonplanar flared FSG to account for lumbar curvature. Laminar and pulsatile blood flow was simulated by numerically solving Navier-Stokes equations. A physiologically realistic flow rate waveform was prescribed at the inlet, while downstream vasculature was modeled using a lumped parameter 3-element windkessel model. No slip boundary conditions were imposed at the FSG walls, which were assumed to be rigid. While resting simulations were performed on all the FSGs, exercise simulations were also performed on a flared FSG to quantify the effect of flaring in different physiologic scenarios. Results: For cycle-averaged inflow of 2.94 L/min (rest) and 4.63 L/min (exercise), 27% of blood flow was channeled into each renal branch at rest and 21% under exercise for all the flared FSGs examined. Although the renal flow waveform was not affected by flaring, flow within the flared FSGs was disturbed. This flow disturbance led to high endothelial cell activation potential (ECAP) values at the renal ostia for all the flared geometries. Reducing the dilation angle or protrusion length and exercise lowered the ECAP values for flared FSGs. Conclusion: Flaring of renal stents has a negligible effect on the time dependence of renal flow rate waveforms and can maintain sufficient renal perfusion at rest and exercise. Local flow patterns are, however, strongly dependent on renal flaring, which creates a local flow disturbance and may increase the thrombogenicity at the renal ostia. Smaller dilation angles, shorter protr
Norman E, Harling M, Skervin AL, et al., 2016, Modified use of thoracic and iliac branch endografts to treat an abdominal aortic aneurysm with an unusually narrow neck, BJR Case Reports, Vol: 2, ISSN: 2055-7159
Abdominal aortic aneurysms with hostile anatomy are a recognized hindrance to the continuing application of endovascular aortic interventions. Narrowed aneurysm necks pose technical difficulties, particularly in the absence of customized endografts. There are multiple suggested approaches to overcome shortened and angulated necks endovascularly; however, none of these address narrowed necks. We present a case where an endograft was used outside of its “instruction for use” by combining the thoracic and iliac branch technologies to overcome this problem. Expanding the use of commercially available endografts for aortic aneurysms with hostile anatomy could have significant practical and financial benefits.
Grover G, Petera A, Rudarakanchana M, et al., 2016, Role of cerebral embolic protection to in thoracic endovascular aortic repair (TEVAR) - a pilot study, CEREBROVASCULAR DISEASES, Vol: 41, Pages: 46-46, ISSN: 1015-9770
Ngo AT, Markar SR, De Lijster MS, et al., 2015, A Systematic Review of Outcomes Following Percutaneous Transluminal Angioplasty and Stenting in the Treatment of Transplant Renal Artery Stenosis, CARDIOVASCULAR AND INTERVENTIONAL RADIOLOGY, Vol: 38, Pages: 1573-1588, ISSN: 0174-1551
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- Citations: 43
Hamady MS, 2015, Medical Errors inIR: Where Are We? A Systematic Review., Journal of Vascular and Interventional Radiology, Vol: 26, Pages: 1741-1743, ISSN: 1535-7732
We conducted a comprehensive literature search on medical errors in Interventional Radiology (IR).Our search only retrieved three studies, which quantitatively assessed the incidence of errors in IR. A total number of 503 patients were included in the studies. All studies instituted a change in practice in order to reduce the incidence of errors. They have all demonstrated a significant reduction in IR errors following implementation of their proposed intervention. Our search highlights the paucity of studies quantitatively assessing medical errors in IR. We urge further research into the field in order to enhance patient safety.
Alsafi A, Hamady M, 2015, Management of endoleaks after thoracic endografts, Challenging Concepts in Interventional Radiology, Editors: Krokidis, Ahmed, Sabharwal, Publisher: Oxford University Press, USA, ISBN: 9780199664382
Thic case-based guide covers a wealth of challenging concepts in interventional radiology and endovascular procedures.
Rafii-Tari H, Riga C, Payne C, et al., 2015, Reducing contact forces in the arch and supra-aortic vessels using the Magellan robot, Journal of Vascular Surgery, ISSN: 1097-6809
Kandail H, Hamady M, Xu XY, 2015, Comparison of blood flow in branched and fenestrated stent-grafts for endovascular repair of abdominal aortic aneurysms., Journal of Endovascular Therapy, Vol: 22, Pages: 578-590, ISSN: 1545-1550
PURPOSE: To report a computational study assessing the hemodynamic outcomes of branched stent-grafts (BSGs) for different anatomic variations. METHODS: Idealized models of BSGs and fenestrated stent-grafts (FSGs) were constructed with different visceral takeoff angles (ToA) and lateral aortic neck angles. ToA was defined as the angle between the centerlines of the main stent-graft and side branch, with 90° representing normal alignment, and 30° and 120° representing angulated side branches. Computational simulations were performed by solving the conservation equations governing the blood flow under physiologically realistic conditions. RESULTS: The largest renal flow recirculation zones (FRZs) were observed in FSGs at a ToA of 30°, and the smallest FRZ was also found in FSGs (at a ToA of 120°). For straight-neck stent-grafts with a ToA of 90°, mean flow in each renal artery was 0.54, 0.46, and 0.62 L/min in antegrade BSGs, retrograde BSGs, and FSGs, respectively. For angulated stent-grafts, the corresponding values were 0.53, 0.48, and 0.63 L/min. All straight-neck stent-grafts experienced equal cycle-averaged displacement forces of 1.25, 1.69, and 1.95 N at ToAs of 30°, 90°, and 120°, respectively. Angulated main stent-grafts experienced an equal cycle-averaged displacement force of 3.6 N. CONCLUSION: The blood flow rate in renal arteries depends on the configuration of the stent-graft, with an FSG giving maximum renal flow and a retrograde BSG resulting in minimum renal flow. Nevertheless, the difference was small, up to 0.09 L/min. Displacement forces exerted on stent-grafts are very sensitive to lateral neck angle but not on the configuration of the stent-graft.
Hodgkinson JD, Cheshire N, Bicknell C, et al., 2015, A novel endovascular treatment for long-standing high-flow arteriovenous fistula, JOURNAL OF VASCULAR SURGERY, Vol: 61, Pages: 1321-1323, ISSN: 0741-5214
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- Citations: 2
Athanasopoulos LV, Bicknell CD, Anderson JR, et al., 2015, Leiomyosarcoma of the Thoracic Aorta in a Patient with Hypertrophic Cardiomyopathy, ANNALS OF VASCULAR SURGERY, Vol: 29, ISSN: 0890-5096
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- Citations: 1
Perera AH, Rudarakanchana N, Bicknell CD, et al., 2015, Silent cerebral infarction and neurocognitive decline following Thoracic Endovascular Aortic Repair, BRITISH JOURNAL OF SURGERY, Vol: 102, Pages: 5-5, ISSN: 0007-1323
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- Citations: 4
Li M, Riga C, Cheung S, et al., 2015, Occupational Radiation Exposure during FEVAR: A Stage-By-Stage Analysis, BRITISH JOURNAL OF SURGERY, Vol: 102, Pages: 23-23, ISSN: 0007-1323
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- Citations: 1
Hamady M, Mortada H, Zissis G, 2015, The photometric properties of microwave high intensity discharge (HID) lamps, Journal of Light and Visual Environment, Vol: 39, Pages: 26-34, ISSN: 0387-8805
This paper calculates the visible radiations of discharges sustained by a microwave (mw) electromagnetic field of a high intensity discharge (HID) lamp. A microwave Mercury (Hg) lamp is considered to be excited by microwave electromagnetic fields in a cylindrical TM010 mode. A 2.45 GHz microwave generator is going to be used to sustain a stable plasma column with discharge gases. A numerical model is used to obtain the power balance in the discharge based on a solution to the Elenbaas-Heller equation for the gas temperature, and a simple "skin depth" model to describe the penetration of the maintenance electric field in the discharge. The obtained plasma for the discharge is assumed to be at local thermodynamic equilibrium (LTE) with no diffusion. Classical spectral line broadening theory is used to provide information on the visible spectrum. However, this theory is inadequate to describe the UV and IR portion of the spectrum, so self-consistent modeling of these discharges is not possible at present and only visible radiations are considered. We show in this work that an increase in electric power does not necessarily lead to an increase in the visible radiation of mw HID lamp. The photometric curve of a pure Hg mw lamp is also calculated. The lamp volume is subdivided into meshes and a local absorption and emission coefficients is assigned to each mesh. A model based on ray tracing method is employed to simulate the radiation transport in these lamps. The line profile is obtained by the convolution of the Lorentzian and Quasi-static profiles. The output flux, luminous flux, luminous efficacy, the Correlated Color Temperature (CCT) and photometric curves of the lamp are therefore obtained.
Cuschieri SA, Hanna GB, 2015, Preface, Essential Surgical Practice: Higher Surgical Training in General Surgery, Fifth Edition, Pages: ix-615, ISBN: 9781444137613
The stomach has an irregular pyriform shape tapering towards the duodenum and curved anteriorly so that its proximal (cardiac) orifice at the junction with the oesophagus and the distal end (pyloric sphincter) are at a more posterior plane near the retroperitoneum than the middle section (body) of the organ. It is anatomically divisible into three parts: the fundus, body and pyloric regions (antrum and pyloric canal). The fundus is the globular proximal portion to the left of the oesophagus separated from it by the cardiac notch and attached by fascia to the left crus and adjacent diaphragm and the gastrophrenic peritoneal fold. The pyloric region extends from the angular notch on the lesser curvature to the pyloric sphincter and consists of the antrum (proximal tapering portion) and the pyloric canal (tubular distal part just proximal to the pyloric sphincter), which is made up of a thickening of the circular muscle coat discontinuous with the equivalent muscle layer of the duodenum. The site of the pylorus is marked by a shallow superficial serosal notch and by the two veins of Mayo (superior and inferior) that cross its anterior surface. The anterior wall of the stomach is more voluminous that the posterior wall and this is important in antireflux surgery.
Choong AMTL, Das S, Mulrenan N, et al., 2014, Don't get in a flap!: A case report of progression through the spectrum of an acute aortic syndrome, VASCULAR, Vol: 22, Pages: 454-457, ISSN: 1708-5381
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- Citations: 1
Rolls AE, Riga CV, Bicknell CD, et al., 2014, Robot-Assisted Uterine Artery Embolization: A First-in-Woman Safety Evaluation of the Magellan System, JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY, Vol: 25, Pages: 1841-1848, ISSN: 1051-0443
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- Citations: 23
Alsafi A, Bicknell CD, Rudarakanchana N, et al., 2014, Endovascular treatment of thoracic aortic aneurysms with a short proximal landing zone using scalloped endografts, JOURNAL OF VASCULAR SURGERY, Vol: 60, Pages: 1499-1506, ISSN: 0741-5214
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- Citations: 30
Kandail H, Hamady M, Xu XY, 2014, Patient-specific analysis of displacement forces acting on fenestrated stent grafts for endovascular aneurysm repair, JOURNAL OF BIOMECHANICS, Vol: 47, Pages: 3546-3554, ISSN: 0021-9290
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- Citations: 29
Banerjee S, Bentley P, Hamady M, et al., 2014, Intra-Arterial Immunoselected CD34+ Stem Cells for Acute Ischemic Stroke, Stem Cells Transl Med, Vol: pii: sctm.2013-0178. [Epub ahead of print]
Perera AH, Rudarakanchana N, Hamady M, et al., 2014, New-generation stent grafts for endovascular management of thoracic pseudoaneurysms after aortic coarctation repair, JOURNAL OF VASCULAR SURGERY, Vol: 60, Pages: 330-336, ISSN: 0741-5214
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- Citations: 13
Rudarakanchana N, Van Herzeele I, Bicknell CD, et al., 2014, Endovascular Repair of Ruptured Abdominal Aortic Aneurysm: Technical and Team Training in an Immersive Virtual Reality Environment, CARDIOVASCULAR AND INTERVENTIONAL RADIOLOGY, Vol: 37, Pages: 920-927, ISSN: 0174-1551
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- Citations: 23
Cundy TP, Di Marco AN, Hamady M, et al., 2014, Giant left paraduodenal hernia., BMJ Case Rep, Vol: 2014
Left paraduodenal hernia (LPDH) is a retrocolic internal hernia of congenital origin that develops through the fossa of Landzert, and extends into the descending mesocolon and left portion of the transverse mesocolon. It carries significant overall risk of mortality, yet delay in diagnosis is not unusual due to subtle and elusive features. Familiarisation with the embryological and anatomical features of this rare hernia is essential for surgical management. This is especially important with respect to vascular anatomy as major mesenteric vessels form intimate relationships with the ventral rim and anterior portion of the hernia. As an illustrative case, we describe our experience with a striking example of LPDH, particularly focusing on the inherent diagnostic challenges and associated critical vascular anatomy. We advocate the role of diagnostic laparoscopy; however caution that decision to safely proceed with laparoscopic repair must occur only with confident identification of the vascular anatomy involved.
Perera AH, Rudarakanchana N, Bicknell CD, et al., 2014, The risk of cerebral microembolisation and silent cerebral infarction with thoracic endovascular aortic repair, Annual Meeting of the Society-of-Academic-and-Research-Surgery, Publisher: WILEY-BLACKWELL, Pages: 7-7, ISSN: 0007-1323
Rippel RA, Rolls AE, Riga CV, et al., 2014, The use of robotic endovascular catheters in the facilitation of transcatheter aortic valve implantation, EUROPEAN JOURNAL OF CARDIO-THORACIC SURGERY, Vol: 45, Pages: 836-841, ISSN: 1010-7940
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- Citations: 16
Rolls AE, Jenkins M, Bicknell CD, et al., 2014, Experience with a novel custom-made fenestrated stent graft in the repair of juxtarenal and type IV thoracoabdominal aneurysms, JOURNAL OF VASCULAR SURGERY, Vol: 59, Pages: 615-U403, ISSN: 0741-5214
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- Citations: 24
Rolls AE, Riga CV, Rudarakanchana N, et al., 2014, Planning for EVAR: the role of modern software., J Cardiovasc Surg (Torino), Vol: 1, Pages: 1-7
Rolls AE, Riga CV, Rudarakanchana N, et al., 2014, Planning for EVAR: the role of modern software, JOURNAL OF CARDIOVASCULAR SURGERY, Vol: 55, Pages: 1-7, ISSN: 0021-9509
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- Citations: 6
Rolls A, Riga C, Bicknell C, et al., 2014, Robotic-guided intervention, Endovascular Interventions: A Case-Based Approach, Pages: 1183-1189, ISBN: 9781461473114
Endovascular intervention is rapidly evolving, allowing more complex pathologies to be managed in a minimally invasive fashion. Although clearly preferable than open surgery for patients with age- or disease-related comorbidities, patient-specific anatomical factors often present a technical challenge even for experienced interventionalists. The use of endovascular robotic technology is a comparatively new field of work considering existing applications in cardiac intervention including atrial fibrillation, mapping, and coronary stent implantation. Several commercially available devices have been designed specifically for use within the vascular tree and utilize a variety of engineering principles to facilitate control of the catheter tip. The Niobe Navigation System (Stereotaxis, USA) was designed for cardiac intervention and consists of two permanent magnets mounted on either side of the fluoroscopy table creating a spherical uniform magnetic field. The computer workstation allows the operator to select the desired field vectors by changing the orientation of the outer magnets relative to each other. The catheter tip has small magnetic implants, which are navigated by the magnetic field.
Banerjee S, Bentley P, Hamady M, et al., 2014, Intra-arterial immunoselected CD34+ stem cells for acute ischemic stroke, Stem Cells Translational Medicine, Vol: 3, Pages: 1322-1331, ISSN: 2157-6564
Treatment with CD34+ hematopoietic stem/progenitor cells has been shown to improve functional recovery in nonhuman models of ischemic stroke via promotion of angiogenesis and neurogenesis. We aimed to determine the safety and feasibility of treatment with CD34+ cells delivered intraarterially in patients with acute ischemic stroke. This was the first study in human subjects. We performed a prospective, nonrandomized, open-label, phase I study of autologous, immunoselected CD34+ stem/progenitor cell therapy in patients presenting within 7 days of onset with severe anterior circulation ischemic stroke (National Institutes of Health Stroke Scale [NIHSS] score ‡8). CD34+ cells were collected from the bone marrow of the subjects before being delivered by catheter angiography into the ipsilesional middle cerebral artery. Eighty-two patients with severe anterior circulation ischemic stroke were screened, of whom five proceeded to treatment. The common reasons for exclusion were age >80 years (n = 19); medical instability (n = 17), and significant carotid stenosis (n = 13). The procedure was well tolerated in all patients, and no significant treatment-related adverse effects occurred. All patients showed improvements in clinical functional scores (Modified Rankin Score and NIHSS score) and reductions in lesion volume during a 6-month follow-up period. Autologous CD34+ selected stem/progenitor cell therapy delivered intra-arterially into the infarct territory can be achieved safely in patients with acute ischemic stroke. Future studies that address eligibility criteria, dosage, delivery site, and timing and that use surrogate imaging markers of outcome are desirable before larger scale clinical trials.
Willicombe M, Sandhu B, Brookes P, et al., 2014, Postanastomotic Transplant Renal Artery Stenosis: Association With <i>De Novo</i> Class II Donor-Specific Antibodies, AMERICAN JOURNAL OF TRANSPLANTATION, Vol: 14, Pages: 133-143, ISSN: 1600-6135
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- Citations: 41
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