Michael Dake - Academia.edu (original) (raw)

Papers by Michael Dake

Research paper thumbnail of Prognosis of Aortic Intramural Hematoma With and Without Penetrating Atherosclerotic Ulcer A Clinical and Radiological Analysis

Background—Advances in imaging techniques have increased the recognition of aortic intramural hem... more Background—Advances in imaging techniques have increased the recognition of aortic intramural hematomas (IMHs) and penetrating atherosclerotic ulcers (PAUs); however, distinction between IMH and PAU remains unclear. We intended to clarify differences between IMH coexisting with PAU and IMH not associated with PAU by comparisons of clinical features, imaging findings, and patient outcome to derive the optimal therapeutic approach. Methods and

Research paper thumbnail of Inhibition of vascular endothelial growth factor-mediated neointima progression with angiostatin or paclitaxel

Journal of vascular and interventional radiology : JVIR, 2002

Therapeutic angiogenesis represents a new paradigm for treatment of ischemic vascular syndromes. ... more Therapeutic angiogenesis represents a new paradigm for treatment of ischemic vascular syndromes. However, vascular endothelial growth factor (VEGF) enhances the rate and degree of plaque formation. This study evaluates the potential to block these effects nonspecifically with paclitaxel or specifically with angiostatin. Recombinant human VEGF(165) (rhVEGF) was administrated intramuscularly (2-microg/kg single injection) in combination with adventitial delivery of paclitaxel, angiostatin, or vehicle alone at the site of femoral arterial balloon overdilation injury in New Zealand White rabbits (n = 5 per treatment). Five additional animals with no rhVEGF and no adventitial delivery served as procedural controls. All rabbits were fed according to a 0.25% cholesterol diet beginning 28 days before angioplasty. Treated arteries were harvested after 7 days and evaluated to determine intima-to-media (I/M) ratios, macrophage infiltrate, and endothelial cell density. On histologic analysis, t...

Research paper thumbnail of Vascular endothelial growth factor enhances atherosclerotic plaque progression

Nature medicine, 2001

Vascular endothelial growth factor (VEGF) can promote angiogenesis but may also exert certain eff... more Vascular endothelial growth factor (VEGF) can promote angiogenesis but may also exert certain effects to alter the rate of atherosclerotic plaque development. To evaluate this potential impact on plaque progression, we treated cholesterol-fed mice doubly deficient in apolipoprotein E/apolipoprotein B100 with low doses of VEGF (2 microg/kg) or albumin. VEGF significantly increased macrophage levels in bone marrow and peripheral blood and increased plaque area 5-, 14- and 4-fold compared with controls at weeks 1, 2 and 3, respectively. Plaque macrophage and endothelial cell content also increased disproportionately over controls. In order to confirm that the VEGF-mediated plaque progression was not species-specific, the experiment was repeated in cholesterol-fed rabbits at the three-week timepoint, which showed comparable increases in plaque progression.

Research paper thumbnail of Recommendations for multimodal noninvasive and invasive screening for detection of extracranial venous abnormalities indicative of chronic cerebrospinal venous insufficiency: a position statement of the International Society for Neurovascular Disease

Journal of vascular and interventional radiology : JVIR, 2014

Under the auspices of the International Society for Neurovascular Disease (ISNVD), four expert pa... more Under the auspices of the International Society for Neurovascular Disease (ISNVD), four expert panel committees were created from the ISNVD membership between 2011 and 2012 to determine and standardize noninvasive and invasive imaging protocols for detection of extracranial venous abnormalities indicative of chronic cerebrospinal venous insufficiency (CCSVI). The committees created working groups on color Doppler ultrasound (US), magnetic resonance (MR) imaging, catheter venography (CV), and intravascular US. Each group organized a workshop focused on its assigned imaging modality. Non-ISNVD members from other societies were invited to contribute to the various workshops. More than 60 neurology, radiology, vascular surgery, and interventional radiology experts participated in these workshops and contributed to the development of standardized noninvasive and invasive imaging protocols for the detection of extracranial venous abnormalities indicative of CCSVI. This ISNVD position stat...

Research paper thumbnail of Superior vena cava syndrome after heart transplantation: percutaneous treatment of a complication of bicaval anastomoses

Journal of Thoracic and Cardiovascular Surgery, 1998

Objectives: Our objectives were (1) to investigate the incidence and cause of symptomatic superio... more Objectives: Our objectives were (1) to investigate the incidence and cause of symptomatic superior vena caval anastomotic stenosis and central venous thrombosis in patients receiving heart or heart-lung transplantation and (2) to explore percutaneous methods of thrombolysis and endoluminal intervention to treat these complications. Methods: Review of 1016 cases revealed three cases of superior vena cava syndrome. Anatomy, surgical technique,

Research paper thumbnail of Factors portending endoleak formation after thoracic aortic stent-graft repair of complicated aortic dissection

Circulation. Cardiovascular interventions, 2009

Endoleaks after stent-graft repair of aortic dissections are poorly understood but seem substanti... more Endoleaks after stent-graft repair of aortic dissections are poorly understood but seem substantially different from those seen after aneurysm repair. We studied anatomic and clinical factors associated with endoleaks in patients who underwent stent-graft repair of complicated type B aortic dissections. From 2000 to 2007, 37 patients underwent stent-graft repair of acute (< or =14 days; n=23), subacute (15 to 90 days; n=10) or chronic (>90 days; n=4) complicated type B aortic dissections using the Gore Thoracic Excluder (n=17) or TAG stent-grafts (n=20) under an investigator-sponsored protocol. Endoleaks were classified as imperfect proximal seal, flow through fenestrations or branches, or complex (both). Variables studied included coverage of the left subclavian artery, aortic curvature, completeness of proximal apposition, dissection chronicity, and device used. Endoleaks were found during follow-up (mean, 22 months) in 59% of patients, and they were associated with coverage...

Research paper thumbnail of A novel, catheter-based approach to left ventricular assist device deactivation after myocardial recovery

The Annals of thoracic surgery, 2014

We describe a case of catheter-based embolization and deactivation of a left ventricular assist d... more We describe a case of catheter-based embolization and deactivation of a left ventricular assist device using an Amplatzer plug for a patient demonstrating myocardial recovery after diagnosis of nonischemic cardiomyopathy. This procedure can provide a minimally invasive, low morbidity solution for patients wishing to be separated from left ventricular assist device support who want to avoid invasive surgery for device removal.

Research paper thumbnail of Stent-Graft Therapy for Subclavian Artery Aneurysms and Fistulas: Single-Center Midterm Results

Journal of Vascular and Interventional Radiology, 2000

All devices were deployed successfully with exclusion of the aneurysms and fistulas. There were t... more All devices were deployed successfully with exclusion of the aneurysms and fistulas. There were two procedure-related complications (22%), consisting of groin pseudoaneurysms requiring surgical repair 3 and 9 days after the procedure. One of those patients required additional ...

Research paper thumbnail of Applications of Spiral CT in Endovascular Aortic Interventions

Seminars in Interventional Radiology, 1998

ABSTRACT Spiral computed tomography (CT) and three dimensional (3D) CT angiography have rapidly e... more ABSTRACT Spiral computed tomography (CT) and three dimensional (3D) CT angiography have rapidly emerged as essential imaging studies in the evaluation of patients undergoing endovascular interventions for aortic aneurysms and dissections. Its major advantages are the ability to provide excellent spatial resolution of the aorta and major branch vessels prior to intervention, detection of subtle perigraft leaks following stent-graft treatment of aortic aneurysms, and providing detailed assessment of intimal flap anatomy in acute aortic dissections. The purpose of this article is to describe the technique and application of spiral CT before and after endovascular repair of aortic aneurysms and dissections based upon the 5-year clinical experience at Stanford University.

Research paper thumbnail of Cheese wire fenestration of a chronic juxtarenal dissection flap to facilitate proximal neck fixation during EVAR

Annals of vascular surgery, 2015

To describe successful endovascular repair of a complex chronic aortoiliac dissection facilitated... more To describe successful endovascular repair of a complex chronic aortoiliac dissection facilitated by a unique endovascular fenestration technique at the proximal neck. A 57-year-old man presented with disabling lower extremity claudication and a remote history of medically treated type B aortic dissection. Computed tomographic angiography demonstrated a complex dissection with 7.1-cm false lumen aneurysmal dilatation and significant true lumen compression within bilateral iliac aneurysms and no suitable proximal infrarenal neck free of dissection. Using intravascular ultrasound, guidewires were introduced into true and false lumens. A 9F sheath was placed on the right side, and a 20-ga Chiba needle was positioned at the level of the celiac artery and oriented toward the dissection flap. The needle was advanced to puncture the flap, and a 0.014-in wire was then snared from the true to the false lumen. Shearing of the dissection flap in the juxtarenal segment was performed using a &qu...

Research paper thumbnail of Percutaneous bypass: subintimal recanalization of peripheral occlusive disease with IVUS guided luminal re-entry

Techniques in Vascular and Interventional Radiology, 2004

Angioplasty of chronic total occlusions (CTOs) has lower technical success rates with longer proc... more Angioplasty of chronic total occlusions (CTOs) has lower technical success rates with longer procedure times and poorer outcomes. Subintimal recanalization remains limited by the lack of controlled re-entry into the true lumen of the target vessel. We report our experience using a commercially available catheter-based system equipped with an intravascular ultrasound scanner to achieve controlled true lumen re-entry in patients with peripheral CTOs. In a 4-month period, 6 patients with lower extremity (LE) ischemia from CTOs were treated. Occluded segments were crossed subintimally, and controlled re-entry was secured using the CrossPoint TransAccess catheter. This 6.2 F dual-lumen catheter contains an integrated 64-element phased array intravascular ultrasound scanner enabling targeting of structures. Intravascular ultrasound-guided luminal re-entry was achieved by advancing a 24-gauge needle to a desired length and delivering a 0.014&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; guide wire into the target lumen. The occluded segments were balloon dilated and stented using self-expanding nitinol stents. Effective luminal re-entry and re-establishment of antegrade flow occurred in all 6 patients. Time to recanalization ranged from 5 to 10 minutes. All patients were free of ischemic symptoms at 1 to 5 month follow-up. There were no procedure-related complications. Our preliminary results demonstrate the feasibility of using this catheter system for subintimal recanalization with controlled re-entry in CTOs. This approach can improve the technical success rate, reduce the time of the procedure, and minimize potential complications.

Research paper thumbnail of Stent-Graft Treatment in Diseases of the Thoracic Aorta

Seminars in Interventional Radiology, 1998

ABSTRACT This article offers an historical perspective and overview for treatment of thoracic aor... more ABSTRACT This article offers an historical perspective and overview for treatment of thoracic aortic aneurysms. The classic technique, design, and delivery system are detailed. It outlines patient selection, the endovascular procedure, and interaction with the vascular surgeon. The authors describe their results as well as complications, and give an overview of this new and highly specialized treatment.

Research paper thumbnail of ENDOVASCULAR TREATMENT OF HEPATIC VENOUS OUTFLOW OBSTRUCTION AFTER PIGGYBACK TECHNIQUE LIVER TRANSPLANTATION

Transplantation, 1999

Background. The piggyback technique of orthotopic liver transplantation is an attractive alternat... more Background. The piggyback technique of orthotopic liver transplantation is an attractive alternative that preserves the recipient inferior vena cava and allows uninterrupted venous blood return during the anhepatic phase. As with other transplantation techniques, the vascular anastomoses required by the piggyback technique can develop strictures.

Research paper thumbnail of Development of a Platform to Evaluate and Limit in-Stent Restenosis

Tissue Engineering, 2002

The objective of this work was to develop a platform to evaluate and deliver putative therapeutic... more The objective of this work was to develop a platform to evaluate and deliver putative therapeutic agents for in-stent restenosis. Arterial stenting is applied in more than 60% of balloon angioplasties for treating cardiovascular disease. However, stented arteries encounter accelerated rates of restenosis. No prior platform has allowed evaluation or local management of in-stent restenosis without perturbing the very system being examined. A stainless steel, balloon-expandable stent was modified to serve as an ablumenal drug delivery platform. Several combinations of bioerodible polymer microspheres and gels were evaluated for channel retention under in vitro flow and in vivo conditions. A stent-anchored hybrid system prevented material embolization under all conditions. Unlike prior platforms, these stents do not alter local inflammation or in-stent plaque formation relative to conventional Palmaz-Schatz stents after in vivo deployment. The system also proved sensitive enough to detect plaque reduction with an antirestenotic agent. We conclude that a platform to evaluate and deliver therapeutic agents for in-stent restenosis has been achieved.

Research paper thumbnail of Occurrence of Secondary Ischemic Events Among Persons With Atherosclerotic Vascular Disease

Research paper thumbnail of Endovascular Thrombolytic Therapy for Deep Venous Thrombosis

Seminars in Respiratory and Critical Care Medicine, 1996

Research paper thumbnail of In-Stent Restenosis Limitation with Stent-based Controlled-Release Nitric Oxide: Initial Results in Rabbits1

Radiology, 2004

To evaluate effect of controlled stent-based release of an NO donor to limit in-stent restenosis ... more To evaluate effect of controlled stent-based release of an NO donor to limit in-stent restenosis in rabbits. Bioerodable microspheres containing NO donor or biodegradable polymer (polylactide-co-glycolide-polyethylene glycol) were prepared and loaded in channeled stents. Daily concentrations of NO release from NO-containing microspheres were assayed in vitro. NO- and polymer-containing (control) microsphere-loaded stents were deployed in aortas of New Zealand white rabbits (n = 8). Aortas with stents were harvested at 7 (n = 5) and 28 days (n = 3) and evaluated for cyclic guanosine monophosphate (cGMP) levels (7 days), number of proliferating cell nuclear antigen-positive cells (7 days), and intima-to-media ratio (7 and 28 days), with statistical significance evaluated by using one-way analysis of variance. NO-containing microspheres released NO with an initial bolus in the 1st week, followed by sustained release for the remaining 3 weeks. Significant increase in cGMP levels and decrease in proliferating cell nuclear antigen-positive cells were found at 7 days for the NO-treated group relative to controls (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.05). Intima-to-media ratio in the NO-treated group was reduced by 46% and 32% relative to controls at 7 and 28 days, respectively (mean, 0.14 +/- 0.01 [standard error] vs 0.26 +/- 0.02 at 7 days, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.01; 1.34 +/- 0.05 vs 1.98 +/- 0.08 at 28 days, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.01). Stent-based controlled release of NO donor significantly reduces in-stent restenosis and is associated with increase in vascular cGMP and suppression of proliferation.

Research paper thumbnail of Angiographic Classification of Ovarian Artery–to–Uterine Artery Anastomoses: Initial Observations in Uterine Fibroid Embolization1

Radiology, 2002

To prospectively study and classify the anastomoses between the ovarian and uterine arteries in w... more To prospectively study and classify the anastomoses between the ovarian and uterine arteries in women undergoing uterine fibroid embolization, and to compare the presence of such with procedural failures and premature menopause. Angiographic ovarian artery-to-uterine artery anastomoses were studied in 76 consecutive patients undergoing uterine fibroid embolization. Mean patient age was 44.7 years (range, 29-56 years). Clinical follow-up consisted of a standard questionnaire. Procedural failure and complications were compared with the presence of various types of ovarian artery-to-uterine artery connections. Three types of anastomoses were identified. In type I (33 [21.7%] of 152 arteries), flow from the ovarian artery to the uterus was through anastomoses with the main uterine artery. In type II (six arteries [3.9%]), the ovarian artery supplied the fibroids directly. In type III (10 arteries [6.6%]), the major blood supply to the ovary was from the uterine artery. Seven patients (9%) were considered to have clinical failure, with three of the six women with type II anastomoses being in this group. Three of the five women who experienced menopause after fibroid embolization had bilateral ovarian artery-to-uterine artery anastomoses that were classified as high risk. Delineation of ovarian artery-to-uterine artery anastomosis is of practical relevance in avoiding nontarget ovarian embolization, in identification of those who would be at risk of uterine artery embolization or ovarian failure, and in those in whom the ovarian artery can be embolized safely.

Research paper thumbnail of Endovascular Stent–Graft Placement for the Treatment of Acute Aortic Dissection

New England Journal of Medicine, 1999

The standard treatment for acute aortic dissection is either surgical or medical therapy, dependi... more The standard treatment for acute aortic dissection is either surgical or medical therapy, depending on the morphologic features of the lesion and any associated complications. Irrespective of the form of treatment, the associated mortality and morbidity are considerable. We studied the placement of endovascular stent-grafts across the primary entry tear for the management of acute aortic dissection originating in the descending thoracic aorta. We evaluated the feasibility, safety, and effectiveness of transluminal stent-graft placement over the entry tear in 4 patients with acute type A aortic dissections (which involve the ascending aorta) and 15 patients with acute type B aortic dissections (which are confined to the descending aorta). Dissections involved aortic branches in 14 of the 19 patients (74 percent), and symptomatic compromise of multiple branch vessels was observed in 7 patients (37 percent). The stent-grafts were made of self-expanding stainless-steel covered with woven polyester or polytetrafluoroethylene material. Placement of endovascular stent-grafts across the primary entry tears was technically successful in all 19 patients. Complete thrombosis of the thoracic aortic false lumen was achieved in 15 patients (79 percent), and partial thrombosis was achieved in 4 (21 percent). Revascularization of ischemic branch vessels, with subsequent relief of corresponding symptoms, occurred in 76 percent of the obstructed branches. Three of the 19 patients died within 30 days, for an early mortality rate of 16 percent (95 percent confidence interval, 0 to 32 percent). There were no deaths and no instances of aneurysm or aortic rupture during the subsequent average follow-up period of 13 months. These initial results suggest that stent-graft coverage of the primary entry tear may be a promising new treatment for selected patients with acute aortic dissection. This technique requires further evaluation, however, to assess its therapeutic potential fully.

Research paper thumbnail of Transluminal Placement of Endovascular Stent-Grafts for the Treatment of Descending Thoracic Aortic Aneurysms

New England Journal of Medicine, 1994

The usual treatment for thoracic aortic aneurysms is surgical replacement with a prosthetic graft... more The usual treatment for thoracic aortic aneurysms is surgical replacement with a prosthetic graft, but the associated morbidity and mortality are considerable. We studied the use of transluminally placed endovascular stent-graft devices as an alternative to surgical repair. We evaluated the feasibility, safety, and effectiveness of transluminally placed stent-graft to treat descending thoracic aortic aneurysms in 13 patients over a 24-month period. Atherosclerotic, anastomotic, and post-traumatic true or false aneurysms and aortic dissections were treated. The mean diameter of the aneurysms was 6.1 cm (range, 5 to 8). The endovascular stent-grafts were custom-designed for each patient and were constructed of self-expanding stainless-steel stents covered with woven Dacron grafts. Endovascular placement of the stent-graft prosthesis was successful in all patients. There was complete thrombosis of the thoracic aortic aneurysm surrounding the stent-graft in 12 patients, and partial thrombosis in 1. Two patients initially had small, residual patent proximal tracts into the aneurysm sac, but both tracts thrombosed within two months after the procedure. In four patients, two prostheses were required to bridge the aneurysm adequately. There have been no deaths or instances of paraplegia, stroke, distal embolization, or infection during an average follow-up of 11.6 months. One patient with an extensive chronic aortic dissection required open surgical graft replacement four months later because of progressive dilatation of the arch. These preliminary results demonstrate that endovascular stent-graft repair is safe in highly selected patients with descending thoracic aortic aneurysms. This new method of treatment will, however, require careful long-term evaluation.

Research paper thumbnail of Prognosis of Aortic Intramural Hematoma With and Without Penetrating Atherosclerotic Ulcer A Clinical and Radiological Analysis

Background—Advances in imaging techniques have increased the recognition of aortic intramural hem... more Background—Advances in imaging techniques have increased the recognition of aortic intramural hematomas (IMHs) and penetrating atherosclerotic ulcers (PAUs); however, distinction between IMH and PAU remains unclear. We intended to clarify differences between IMH coexisting with PAU and IMH not associated with PAU by comparisons of clinical features, imaging findings, and patient outcome to derive the optimal therapeutic approach. Methods and

Research paper thumbnail of Inhibition of vascular endothelial growth factor-mediated neointima progression with angiostatin or paclitaxel

Journal of vascular and interventional radiology : JVIR, 2002

Therapeutic angiogenesis represents a new paradigm for treatment of ischemic vascular syndromes. ... more Therapeutic angiogenesis represents a new paradigm for treatment of ischemic vascular syndromes. However, vascular endothelial growth factor (VEGF) enhances the rate and degree of plaque formation. This study evaluates the potential to block these effects nonspecifically with paclitaxel or specifically with angiostatin. Recombinant human VEGF(165) (rhVEGF) was administrated intramuscularly (2-microg/kg single injection) in combination with adventitial delivery of paclitaxel, angiostatin, or vehicle alone at the site of femoral arterial balloon overdilation injury in New Zealand White rabbits (n = 5 per treatment). Five additional animals with no rhVEGF and no adventitial delivery served as procedural controls. All rabbits were fed according to a 0.25% cholesterol diet beginning 28 days before angioplasty. Treated arteries were harvested after 7 days and evaluated to determine intima-to-media (I/M) ratios, macrophage infiltrate, and endothelial cell density. On histologic analysis, t...

Research paper thumbnail of Vascular endothelial growth factor enhances atherosclerotic plaque progression

Nature medicine, 2001

Vascular endothelial growth factor (VEGF) can promote angiogenesis but may also exert certain eff... more Vascular endothelial growth factor (VEGF) can promote angiogenesis but may also exert certain effects to alter the rate of atherosclerotic plaque development. To evaluate this potential impact on plaque progression, we treated cholesterol-fed mice doubly deficient in apolipoprotein E/apolipoprotein B100 with low doses of VEGF (2 microg/kg) or albumin. VEGF significantly increased macrophage levels in bone marrow and peripheral blood and increased plaque area 5-, 14- and 4-fold compared with controls at weeks 1, 2 and 3, respectively. Plaque macrophage and endothelial cell content also increased disproportionately over controls. In order to confirm that the VEGF-mediated plaque progression was not species-specific, the experiment was repeated in cholesterol-fed rabbits at the three-week timepoint, which showed comparable increases in plaque progression.

Research paper thumbnail of Recommendations for multimodal noninvasive and invasive screening for detection of extracranial venous abnormalities indicative of chronic cerebrospinal venous insufficiency: a position statement of the International Society for Neurovascular Disease

Journal of vascular and interventional radiology : JVIR, 2014

Under the auspices of the International Society for Neurovascular Disease (ISNVD), four expert pa... more Under the auspices of the International Society for Neurovascular Disease (ISNVD), four expert panel committees were created from the ISNVD membership between 2011 and 2012 to determine and standardize noninvasive and invasive imaging protocols for detection of extracranial venous abnormalities indicative of chronic cerebrospinal venous insufficiency (CCSVI). The committees created working groups on color Doppler ultrasound (US), magnetic resonance (MR) imaging, catheter venography (CV), and intravascular US. Each group organized a workshop focused on its assigned imaging modality. Non-ISNVD members from other societies were invited to contribute to the various workshops. More than 60 neurology, radiology, vascular surgery, and interventional radiology experts participated in these workshops and contributed to the development of standardized noninvasive and invasive imaging protocols for the detection of extracranial venous abnormalities indicative of CCSVI. This ISNVD position stat...

Research paper thumbnail of Superior vena cava syndrome after heart transplantation: percutaneous treatment of a complication of bicaval anastomoses

Journal of Thoracic and Cardiovascular Surgery, 1998

Objectives: Our objectives were (1) to investigate the incidence and cause of symptomatic superio... more Objectives: Our objectives were (1) to investigate the incidence and cause of symptomatic superior vena caval anastomotic stenosis and central venous thrombosis in patients receiving heart or heart-lung transplantation and (2) to explore percutaneous methods of thrombolysis and endoluminal intervention to treat these complications. Methods: Review of 1016 cases revealed three cases of superior vena cava syndrome. Anatomy, surgical technique,

Research paper thumbnail of Factors portending endoleak formation after thoracic aortic stent-graft repair of complicated aortic dissection

Circulation. Cardiovascular interventions, 2009

Endoleaks after stent-graft repair of aortic dissections are poorly understood but seem substanti... more Endoleaks after stent-graft repair of aortic dissections are poorly understood but seem substantially different from those seen after aneurysm repair. We studied anatomic and clinical factors associated with endoleaks in patients who underwent stent-graft repair of complicated type B aortic dissections. From 2000 to 2007, 37 patients underwent stent-graft repair of acute (< or =14 days; n=23), subacute (15 to 90 days; n=10) or chronic (>90 days; n=4) complicated type B aortic dissections using the Gore Thoracic Excluder (n=17) or TAG stent-grafts (n=20) under an investigator-sponsored protocol. Endoleaks were classified as imperfect proximal seal, flow through fenestrations or branches, or complex (both). Variables studied included coverage of the left subclavian artery, aortic curvature, completeness of proximal apposition, dissection chronicity, and device used. Endoleaks were found during follow-up (mean, 22 months) in 59% of patients, and they were associated with coverage...

Research paper thumbnail of A novel, catheter-based approach to left ventricular assist device deactivation after myocardial recovery

The Annals of thoracic surgery, 2014

We describe a case of catheter-based embolization and deactivation of a left ventricular assist d... more We describe a case of catheter-based embolization and deactivation of a left ventricular assist device using an Amplatzer plug for a patient demonstrating myocardial recovery after diagnosis of nonischemic cardiomyopathy. This procedure can provide a minimally invasive, low morbidity solution for patients wishing to be separated from left ventricular assist device support who want to avoid invasive surgery for device removal.

Research paper thumbnail of Stent-Graft Therapy for Subclavian Artery Aneurysms and Fistulas: Single-Center Midterm Results

Journal of Vascular and Interventional Radiology, 2000

All devices were deployed successfully with exclusion of the aneurysms and fistulas. There were t... more All devices were deployed successfully with exclusion of the aneurysms and fistulas. There were two procedure-related complications (22%), consisting of groin pseudoaneurysms requiring surgical repair 3 and 9 days after the procedure. One of those patients required additional ...

Research paper thumbnail of Applications of Spiral CT in Endovascular Aortic Interventions

Seminars in Interventional Radiology, 1998

ABSTRACT Spiral computed tomography (CT) and three dimensional (3D) CT angiography have rapidly e... more ABSTRACT Spiral computed tomography (CT) and three dimensional (3D) CT angiography have rapidly emerged as essential imaging studies in the evaluation of patients undergoing endovascular interventions for aortic aneurysms and dissections. Its major advantages are the ability to provide excellent spatial resolution of the aorta and major branch vessels prior to intervention, detection of subtle perigraft leaks following stent-graft treatment of aortic aneurysms, and providing detailed assessment of intimal flap anatomy in acute aortic dissections. The purpose of this article is to describe the technique and application of spiral CT before and after endovascular repair of aortic aneurysms and dissections based upon the 5-year clinical experience at Stanford University.

Research paper thumbnail of Cheese wire fenestration of a chronic juxtarenal dissection flap to facilitate proximal neck fixation during EVAR

Annals of vascular surgery, 2015

To describe successful endovascular repair of a complex chronic aortoiliac dissection facilitated... more To describe successful endovascular repair of a complex chronic aortoiliac dissection facilitated by a unique endovascular fenestration technique at the proximal neck. A 57-year-old man presented with disabling lower extremity claudication and a remote history of medically treated type B aortic dissection. Computed tomographic angiography demonstrated a complex dissection with 7.1-cm false lumen aneurysmal dilatation and significant true lumen compression within bilateral iliac aneurysms and no suitable proximal infrarenal neck free of dissection. Using intravascular ultrasound, guidewires were introduced into true and false lumens. A 9F sheath was placed on the right side, and a 20-ga Chiba needle was positioned at the level of the celiac artery and oriented toward the dissection flap. The needle was advanced to puncture the flap, and a 0.014-in wire was then snared from the true to the false lumen. Shearing of the dissection flap in the juxtarenal segment was performed using a &qu...

Research paper thumbnail of Percutaneous bypass: subintimal recanalization of peripheral occlusive disease with IVUS guided luminal re-entry

Techniques in Vascular and Interventional Radiology, 2004

Angioplasty of chronic total occlusions (CTOs) has lower technical success rates with longer proc... more Angioplasty of chronic total occlusions (CTOs) has lower technical success rates with longer procedure times and poorer outcomes. Subintimal recanalization remains limited by the lack of controlled re-entry into the true lumen of the target vessel. We report our experience using a commercially available catheter-based system equipped with an intravascular ultrasound scanner to achieve controlled true lumen re-entry in patients with peripheral CTOs. In a 4-month period, 6 patients with lower extremity (LE) ischemia from CTOs were treated. Occluded segments were crossed subintimally, and controlled re-entry was secured using the CrossPoint TransAccess catheter. This 6.2 F dual-lumen catheter contains an integrated 64-element phased array intravascular ultrasound scanner enabling targeting of structures. Intravascular ultrasound-guided luminal re-entry was achieved by advancing a 24-gauge needle to a desired length and delivering a 0.014&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; guide wire into the target lumen. The occluded segments were balloon dilated and stented using self-expanding nitinol stents. Effective luminal re-entry and re-establishment of antegrade flow occurred in all 6 patients. Time to recanalization ranged from 5 to 10 minutes. All patients were free of ischemic symptoms at 1 to 5 month follow-up. There were no procedure-related complications. Our preliminary results demonstrate the feasibility of using this catheter system for subintimal recanalization with controlled re-entry in CTOs. This approach can improve the technical success rate, reduce the time of the procedure, and minimize potential complications.

Research paper thumbnail of Stent-Graft Treatment in Diseases of the Thoracic Aorta

Seminars in Interventional Radiology, 1998

ABSTRACT This article offers an historical perspective and overview for treatment of thoracic aor... more ABSTRACT This article offers an historical perspective and overview for treatment of thoracic aortic aneurysms. The classic technique, design, and delivery system are detailed. It outlines patient selection, the endovascular procedure, and interaction with the vascular surgeon. The authors describe their results as well as complications, and give an overview of this new and highly specialized treatment.

Research paper thumbnail of ENDOVASCULAR TREATMENT OF HEPATIC VENOUS OUTFLOW OBSTRUCTION AFTER PIGGYBACK TECHNIQUE LIVER TRANSPLANTATION

Transplantation, 1999

Background. The piggyback technique of orthotopic liver transplantation is an attractive alternat... more Background. The piggyback technique of orthotopic liver transplantation is an attractive alternative that preserves the recipient inferior vena cava and allows uninterrupted venous blood return during the anhepatic phase. As with other transplantation techniques, the vascular anastomoses required by the piggyback technique can develop strictures.

Research paper thumbnail of Development of a Platform to Evaluate and Limit in-Stent Restenosis

Tissue Engineering, 2002

The objective of this work was to develop a platform to evaluate and deliver putative therapeutic... more The objective of this work was to develop a platform to evaluate and deliver putative therapeutic agents for in-stent restenosis. Arterial stenting is applied in more than 60% of balloon angioplasties for treating cardiovascular disease. However, stented arteries encounter accelerated rates of restenosis. No prior platform has allowed evaluation or local management of in-stent restenosis without perturbing the very system being examined. A stainless steel, balloon-expandable stent was modified to serve as an ablumenal drug delivery platform. Several combinations of bioerodible polymer microspheres and gels were evaluated for channel retention under in vitro flow and in vivo conditions. A stent-anchored hybrid system prevented material embolization under all conditions. Unlike prior platforms, these stents do not alter local inflammation or in-stent plaque formation relative to conventional Palmaz-Schatz stents after in vivo deployment. The system also proved sensitive enough to detect plaque reduction with an antirestenotic agent. We conclude that a platform to evaluate and deliver therapeutic agents for in-stent restenosis has been achieved.

Research paper thumbnail of Occurrence of Secondary Ischemic Events Among Persons With Atherosclerotic Vascular Disease

Research paper thumbnail of Endovascular Thrombolytic Therapy for Deep Venous Thrombosis

Seminars in Respiratory and Critical Care Medicine, 1996

Research paper thumbnail of In-Stent Restenosis Limitation with Stent-based Controlled-Release Nitric Oxide: Initial Results in Rabbits1

Radiology, 2004

To evaluate effect of controlled stent-based release of an NO donor to limit in-stent restenosis ... more To evaluate effect of controlled stent-based release of an NO donor to limit in-stent restenosis in rabbits. Bioerodable microspheres containing NO donor or biodegradable polymer (polylactide-co-glycolide-polyethylene glycol) were prepared and loaded in channeled stents. Daily concentrations of NO release from NO-containing microspheres were assayed in vitro. NO- and polymer-containing (control) microsphere-loaded stents were deployed in aortas of New Zealand white rabbits (n = 8). Aortas with stents were harvested at 7 (n = 5) and 28 days (n = 3) and evaluated for cyclic guanosine monophosphate (cGMP) levels (7 days), number of proliferating cell nuclear antigen-positive cells (7 days), and intima-to-media ratio (7 and 28 days), with statistical significance evaluated by using one-way analysis of variance. NO-containing microspheres released NO with an initial bolus in the 1st week, followed by sustained release for the remaining 3 weeks. Significant increase in cGMP levels and decrease in proliferating cell nuclear antigen-positive cells were found at 7 days for the NO-treated group relative to controls (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.05). Intima-to-media ratio in the NO-treated group was reduced by 46% and 32% relative to controls at 7 and 28 days, respectively (mean, 0.14 +/- 0.01 [standard error] vs 0.26 +/- 0.02 at 7 days, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.01; 1.34 +/- 0.05 vs 1.98 +/- 0.08 at 28 days, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.01). Stent-based controlled release of NO donor significantly reduces in-stent restenosis and is associated with increase in vascular cGMP and suppression of proliferation.

Research paper thumbnail of Angiographic Classification of Ovarian Artery–to–Uterine Artery Anastomoses: Initial Observations in Uterine Fibroid Embolization1

Radiology, 2002

To prospectively study and classify the anastomoses between the ovarian and uterine arteries in w... more To prospectively study and classify the anastomoses between the ovarian and uterine arteries in women undergoing uterine fibroid embolization, and to compare the presence of such with procedural failures and premature menopause. Angiographic ovarian artery-to-uterine artery anastomoses were studied in 76 consecutive patients undergoing uterine fibroid embolization. Mean patient age was 44.7 years (range, 29-56 years). Clinical follow-up consisted of a standard questionnaire. Procedural failure and complications were compared with the presence of various types of ovarian artery-to-uterine artery connections. Three types of anastomoses were identified. In type I (33 [21.7%] of 152 arteries), flow from the ovarian artery to the uterus was through anastomoses with the main uterine artery. In type II (six arteries [3.9%]), the ovarian artery supplied the fibroids directly. In type III (10 arteries [6.6%]), the major blood supply to the ovary was from the uterine artery. Seven patients (9%) were considered to have clinical failure, with three of the six women with type II anastomoses being in this group. Three of the five women who experienced menopause after fibroid embolization had bilateral ovarian artery-to-uterine artery anastomoses that were classified as high risk. Delineation of ovarian artery-to-uterine artery anastomosis is of practical relevance in avoiding nontarget ovarian embolization, in identification of those who would be at risk of uterine artery embolization or ovarian failure, and in those in whom the ovarian artery can be embolized safely.

Research paper thumbnail of Endovascular Stent–Graft Placement for the Treatment of Acute Aortic Dissection

New England Journal of Medicine, 1999

The standard treatment for acute aortic dissection is either surgical or medical therapy, dependi... more The standard treatment for acute aortic dissection is either surgical or medical therapy, depending on the morphologic features of the lesion and any associated complications. Irrespective of the form of treatment, the associated mortality and morbidity are considerable. We studied the placement of endovascular stent-grafts across the primary entry tear for the management of acute aortic dissection originating in the descending thoracic aorta. We evaluated the feasibility, safety, and effectiveness of transluminal stent-graft placement over the entry tear in 4 patients with acute type A aortic dissections (which involve the ascending aorta) and 15 patients with acute type B aortic dissections (which are confined to the descending aorta). Dissections involved aortic branches in 14 of the 19 patients (74 percent), and symptomatic compromise of multiple branch vessels was observed in 7 patients (37 percent). The stent-grafts were made of self-expanding stainless-steel covered with woven polyester or polytetrafluoroethylene material. Placement of endovascular stent-grafts across the primary entry tears was technically successful in all 19 patients. Complete thrombosis of the thoracic aortic false lumen was achieved in 15 patients (79 percent), and partial thrombosis was achieved in 4 (21 percent). Revascularization of ischemic branch vessels, with subsequent relief of corresponding symptoms, occurred in 76 percent of the obstructed branches. Three of the 19 patients died within 30 days, for an early mortality rate of 16 percent (95 percent confidence interval, 0 to 32 percent). There were no deaths and no instances of aneurysm or aortic rupture during the subsequent average follow-up period of 13 months. These initial results suggest that stent-graft coverage of the primary entry tear may be a promising new treatment for selected patients with acute aortic dissection. This technique requires further evaluation, however, to assess its therapeutic potential fully.

Research paper thumbnail of Transluminal Placement of Endovascular Stent-Grafts for the Treatment of Descending Thoracic Aortic Aneurysms

New England Journal of Medicine, 1994

The usual treatment for thoracic aortic aneurysms is surgical replacement with a prosthetic graft... more The usual treatment for thoracic aortic aneurysms is surgical replacement with a prosthetic graft, but the associated morbidity and mortality are considerable. We studied the use of transluminally placed endovascular stent-graft devices as an alternative to surgical repair. We evaluated the feasibility, safety, and effectiveness of transluminally placed stent-graft to treat descending thoracic aortic aneurysms in 13 patients over a 24-month period. Atherosclerotic, anastomotic, and post-traumatic true or false aneurysms and aortic dissections were treated. The mean diameter of the aneurysms was 6.1 cm (range, 5 to 8). The endovascular stent-grafts were custom-designed for each patient and were constructed of self-expanding stainless-steel stents covered with woven Dacron grafts. Endovascular placement of the stent-graft prosthesis was successful in all patients. There was complete thrombosis of the thoracic aortic aneurysm surrounding the stent-graft in 12 patients, and partial thrombosis in 1. Two patients initially had small, residual patent proximal tracts into the aneurysm sac, but both tracts thrombosed within two months after the procedure. In four patients, two prostheses were required to bridge the aneurysm adequately. There have been no deaths or instances of paraplegia, stroke, distal embolization, or infection during an average follow-up of 11.6 months. One patient with an extensive chronic aortic dissection required open surgical graft replacement four months later because of progressive dilatation of the arch. These preliminary results demonstrate that endovascular stent-graft repair is safe in highly selected patients with descending thoracic aortic aneurysms. This new method of treatment will, however, require careful long-term evaluation.