Scott Mitchell - Academia.edu (original) (raw)
Papers by Scott Mitchell
Computer graphics forum : journal of the European Association for Computer Graphics, 2016
We introduce an algorithmic framework for tuning the spatial density of disks in a maximal random... more We introduce an algorithmic framework for tuning the spatial density of disks in a maximal random packing, without changing the sizing function or radii of disks. Starting from any maximal random packing such as a Maximal Poisson-disk Sampling (MPS), we iteratively relocate, inject (add), or eject (remove) disks, using a set of three successively more-aggressive local operations. We may achieve a user-defined density, either more dense or more sparse, almost up to the theoretical structured limits. The tuned samples are conflict-free, retain coverage maximality, and, except in the extremes, retain the blue noise randomness properties of the input. We change the density of the packing one disk at a time, maintaining the minimum disk separation distance and the maximum domain coverage distance required of any maximal packing. These properties are local, and we can handle spatially-varying sizing functions. Using fewer points to satisfy a sizing function improves the efficiency of some...
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The Annals of Thoracic Surgery, Aug 1, 2010
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Proceedings of Spie the International Society For Optical Engineering, Feb 9, 2006
We are developing an all fiber laser system optimized for providing input pulses for short pulse ... more We are developing an all fiber laser system optimized for providing input pulses for short pulse (1-10ps), high energy (~1kJ) glass laser systems. Fiber lasers are ideal solutions for these systems as they are highly reliable and enable long term stable operation. The design requirements for this application are very different than those commonly seen in fiber lasers. High-energy lasers often have low repetition rates (as low as one pulse every few hours), and thus high average power and efficiency are of little practical value. What is of high value is pulse energy, high signal to noise ratio (expressed as pre-pulse contrast), good beam quality, consistent output parameters and timing. Our system focuses on optimizing these parameters. Our prototype system consists of a mode-locked fiber laser, a compressed pulse fiber amplifier, a "pulse cleaner", a chirped fiber Bragg grating, pulse selectors, a transport fiber system and a large mode area fiber amplifier. We will review the system and present theoretical and experimental studies of critical aspects, in particular the requirement for high pre-pulse contrast.
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Semin Vasc Surg, 2000
Diseases of the thoracic aorta pose a significant challenge to the surgeon because of the complex... more Diseases of the thoracic aorta pose a significant challenge to the surgeon because of the complexity of the disease and the characteristics of the patient population. Frequent comorbidities and increasing age account for mortality rates between 5% and 20% for surgical repair of descending thoracic aortic aneurysms and in excess of 50% for Stanford type B aortic dissections, when complicated by preoperative end-organ ischemia. Endovascular techniques of fenestration, stenting, and stent-grafting have emerged as viable alternatives to conventional surgery in these patients. The authors review their experience using endovascular stent-grafts in the treatment of 103 patients with descending thoracic aortic aneurysms and 19 patients with acute aortic dissections. Fenestration and stenting are also addressed as adjuvant therapies in the treatment of complicated aortic dissections. Actuarial survival for aneurysms was 81% +/- 5% at 1 year and 73% +/- 5% at 2 years. Stent-grafting for acute aortic dissections achieved instant relief of symptoms in 71% of cases with an early procedural mortality of 16%, and endovascular revascularization of ischemic beds was achieved in 93% +/- 4% of cases of peripheral or visceral ischemia. The authors' experience supports the use of endovascular techniques in the treatment of thoracic aortic pathologic conditions. Longer follow-up and results of ongoing trials that use newer devices will help define the indications for their future use.
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Journal of Cardiothoracic and Vascular Anesthesia, Sep 1, 2007
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Journal of Global Buddhism, 2012
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The Journal of Physical Chemistry, 1994
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The Journal of Thoracic and Cardiovascular Surgery, 2007
The RIFLE criteria are new international consensus definitions for acute kidney injury introduced... more The RIFLE criteria are new international consensus definitions for acute kidney injury introduced to facilitate research across disciplines. We identified risk factors for acute kidney injury, renal replacement therapy, and mortality using the RIFLE criteria (RIFLE = risk, injury, failure, loss, end stage) in patients undergoing deep hypothermic circulatory arrest for aortic arch reconstruction. A single-center retrospective cohort study of 267 patients undergoing aortic arch surgery with deep hypothermic circulatory arrest was conducted between July 2001 and October 2005. Known predictors (age, chronic kidney disease, surgery status, redo, diabetes, hypertension, blood transfusion, bypass, and deep hypothermic circulatory arrest time) were used in multivariate logistic regression models for acute kidney injury, renal replacement therapy, and mortality. Mean age was 64 years (range 23-89 years) with 166 men (62%). Seventy-five (28%) had RIFLE scores of I or F, and 22 (8%) required dialysis. Risk factors for acute kidney injury were hypertension (odds ratio [OR] = 2.17; 95% confidence intervals [CI], 1.14-4.15), chronic kidney disease (OR = 9.04; 95% CI, 1.97-41.59), packed red blood cells greater than 5 units (OR = 2.37; 95% CI, 1.20-4.69), and admission creatinine/Modification of Diet in Renal Disease predicted creatinine ratio greater than 1 (OR = 3.54; 95% CI, 1.95-6.45). Risk factors for mortality were age (per 10 years) (OR = 2.35; 95% CI, 1.35-4.06), AKI (RIFLE class R, I, or F) (OR = 4.60; 95% CI, 1.34-15.77), and cerebrovascular accident (OR = 19.1; 95% CI, 4.96-73.58). Mortality increased with each RIFLE stratification (RIFLE class 0 = 3%, R = 9%, I = 12%, and F = 38%). Acute kidney injury as defined according to the RIFLE classification is a risk factor for mortality and will be useful in future studies of renal dysfunction in thoracic aortic surgery.
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The Annals of Thoracic Surgery, 2004
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The Journal of Thoracic and Cardiovascular Surgery, Aug 31, 2009
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Plastic and Reconstructive Surgery, Jun 1, 2007
Current theory on normal cranial suture fusion entrusts the dura with the regulatory role. Studie... more Current theory on normal cranial suture fusion entrusts the dura with the regulatory role. Studies suggest that the dura responds to stress with changes in gene expression. Noggin (bone morphogenetic protein inhibitor) expression is decreased in normal (rat and mouse) cranial suture fusion, but its role in craniosynostosis and the response to stress has not been studied. Posterior frontal (fusing) and sagittal (patent) rat cranial sutures were held static, oscillated, or distracted for 10 days in an organ culture microdistraction device beginning at 5 days of age (n = 30 sutures, or 10 sutures per group). The percentage of fusion equaled the score received for bony closure. Noggin, Runx2, and alkaline phosphatase expression was localized by immunohistochemistry for all groups. Both the posterior frontal and sagittal sutures demonstrated a significant (p < 0.05) increase in fusion percentage with oscillation relative to the static control. Noggin was not expressed in the fusing posterior frontal suture but was expressed in the normally patent sagittal suture. Conversely, Runx2 was expressed in the posterior frontal suture but not in the sagittal suture. However, when a mechanical stress was applied, both the posterior frontal and sagittal sutures expressed Runx2 but not Noggin, as in the static fusing suture. The application of mechanical stress to cranial sutures results in fusion of both the posterior frontal suture and the normally patent sagittal suture. Runx2 is expressed but Noggin is not expressed. Thus, mechanical stress influences sutural fusion and may play a role in craniosynostosis.
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The Journal of Physical Chemistry B, Sep 1, 2003
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Cardiol Clin, 1999
ABSTRACT Technology is proceeding at a very brisk pace. Harnessing that technology for clinical u... more ABSTRACT Technology is proceeding at a very brisk pace. Harnessing that technology for clinical use is both a challenge and an opportunity. This combination of surgical and interventional methods has allowed for improved clinical outcomes in certain complex aortic problems. This article explores and discusses new techniques used in detection and treatment of diseases of the thoracic aorta.
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Journal of Vascular Surgery, Feb 1, 1997
Purpose: Patients with aneurysmal disease involving both the descending thoracic and abdominal ao... more Purpose: Patients with aneurysmal disease involving both the descending thoracic and abdominal aorta have historically required simultaneous or sequential conventional operations, but the morbidity rate is high with either approach in these patients, who often exhibit coexisting cardiopulmonary disease. Transluminally placed endovascular grafts have recently been developed for repair of aortic aneurysms, and we have implemented these techniques to eliminate the need for a thoracotomy in patients with multilevel aortic disease.Methods: Since January 1994, 18 patients have undergone conventional abdominal aortic replacement with endovascular stent-graft placement into the descending thoracic aorta under fluoroscopic guidance through a 10 mm Dacron side limb off the abdominal graft. Abdominal aortic replacement required a tube graft in eight patients and bifurcated grafts in 10 patients. Thoracic stent-grafts (custom fabricated, woven Dacron covered, self-expandable stents) averaged 12.2 ± 4.2 cm (mean ± SD) in length.Results: One patient died, resulting in a hospital mortality rate of 6%. No patients required further surgical intervention to treat their aortic disease. Seventeen patients (94%) are currently well 14 ± 8 months after surgery (range, 3 to 29 months) with completely excluded thoracic aortic disease, no stent migration, and no change in stent configuration documented by serial radiologic examinations.Conclusions: Simultaneous abdominal aortic replacement and deployment of a thoracic stent-graft can safely exclude multilevel aortic aneurysmal disease and may be a valuable treatment option for these otherwise high-risk patients. (J Vasc Surg 1997;25:332-40.)
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The Annals of Thoracic Surgery, Jun 1, 1999
Objective. The feasibility and efficacy trial of an endovascular stent-grafting system for the tr... more Objective. The feasibility and efficacy trial of an endovascular stent-grafting system for the treatment of aneurysms of the descending thoracic aorta was investigated.Methods. After Institutional Review Board approval, 103 patients (mean age 69 years) underwent stent graft repair of a descending thoracic aortic aneurysm between July 1992 and November 1997. The stent graft was fabricated using self-expanding “Z” stents covered by a woven Dacron tube graft. Follow-up, which averaged 22 months, was 100% complete. Simultaneous open abdominal aortic aneurysm repair was performed in 19 patients.Results. Complete aneurysm thrombosis was achieved in 86 patients (83%). Early mortality, defined as a death during the same hospitalization or in less than 30 days, was 9 ± 3%, and was significantly associated with preoperative cerebrovascular accident (CVA) or myocardial infarction. Major perioperative morbidity occurred in 31 patients, and included paraplegia in 3, CVA in 7, and respiratory insufficiency in 12 patients each. Actuarial survival was 81 ± 4% at 1 year, and 73 ± 5% at 2 years. Treatment failure (including all late, sudden, unexplained deaths) occurred in 38 patients, and only 53 ± 10% of patients were free of treatment failure at 3.7 years. Five patients required late operative therapy for endoleaks associated with aneurysm enlargement.Conclusions. Satisfactory results were achieved using this “first-generation” homemade stent graft device. Mortality and morbidity occurred frequently, but may have been associated with the high-risk character of this patient population. Medium-term results were acceptable, but continued aortic enlargement, with the late development of endoleaks, is a significant concern. Second-generation devices with commercial development, coupled with this initial experience, should allow improved clinical results in the future. Longer term follow-up is still necessary to fully define the efficacy of this endovascular approach.
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J Vasc Surg, 1993
Intravascular ultrasonography, balloon angioplasty, stent placement, and endovascular septal fene... more Intravascular ultrasonography, balloon angioplasty, stent placement, and endovascular septal fenestration have been used in the evaluation and treatment of vascular complications of acute and chronic aortic dissection in five patients. There were three men and two women with an average age of 52 years (range 39 to 64 years). There were three chronic type A dissections, one acute type B, and one subacute type B dissection. Intravascular ultrasonography was used in all five cases. The three patients with chronic type A dissections underwent unilateral renal artery angioplasty (RA PTA) and stent placement; one patient with an acute type B dissection and associated fibromuscular dysplasia underwent bilateral RA PTA without stent placement. These procedures were performed to ameliorate severe hypertension. The final patient, with a subacute type B dissection, underwent iliac artery stenting to correct severe lower extremity ischemia. During a second intervention, this patient, who also had bowel ischemia and nonresolving acute renal failure, underwent balloon dilatation of a preexisting septal fenestration to augment visceral blood supply and bilateral RA PTA and stent placement in an effort to improve renal function. This patient eventually died of gut ischemia. After RA PTA and stent placement, one patient had a major intrarenal hemorrhage that required coil embolization and transfusion. In the four survivors, RA PTA and stent placement resulted in immediate improvement in blood pressure control. This response has been sustained during follow-up intervals ranging from 8 to 18 months (average 10 months). Intravascular ultrasonography can clearly demonstrate the pathologic anatomy associated with aortic dissection (even when angiography is ambiguous) and is essential for guiding therapeutic endovascular interventions. Further exploration of the efficacy of these endovascular techniques is warranted in this high-risk group of patients with aortic dissection who have appropriate clinical indications.
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Computer graphics forum : journal of the European Association for Computer Graphics, 2016
We introduce an algorithmic framework for tuning the spatial density of disks in a maximal random... more We introduce an algorithmic framework for tuning the spatial density of disks in a maximal random packing, without changing the sizing function or radii of disks. Starting from any maximal random packing such as a Maximal Poisson-disk Sampling (MPS), we iteratively relocate, inject (add), or eject (remove) disks, using a set of three successively more-aggressive local operations. We may achieve a user-defined density, either more dense or more sparse, almost up to the theoretical structured limits. The tuned samples are conflict-free, retain coverage maximality, and, except in the extremes, retain the blue noise randomness properties of the input. We change the density of the packing one disk at a time, maintaining the minimum disk separation distance and the maximum domain coverage distance required of any maximal packing. These properties are local, and we can handle spatially-varying sizing functions. Using fewer points to satisfy a sizing function improves the efficiency of some...
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The Annals of Thoracic Surgery, Aug 1, 2010
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Proceedings of Spie the International Society For Optical Engineering, Feb 9, 2006
We are developing an all fiber laser system optimized for providing input pulses for short pulse ... more We are developing an all fiber laser system optimized for providing input pulses for short pulse (1-10ps), high energy (~1kJ) glass laser systems. Fiber lasers are ideal solutions for these systems as they are highly reliable and enable long term stable operation. The design requirements for this application are very different than those commonly seen in fiber lasers. High-energy lasers often have low repetition rates (as low as one pulse every few hours), and thus high average power and efficiency are of little practical value. What is of high value is pulse energy, high signal to noise ratio (expressed as pre-pulse contrast), good beam quality, consistent output parameters and timing. Our system focuses on optimizing these parameters. Our prototype system consists of a mode-locked fiber laser, a compressed pulse fiber amplifier, a "pulse cleaner", a chirped fiber Bragg grating, pulse selectors, a transport fiber system and a large mode area fiber amplifier. We will review the system and present theoretical and experimental studies of critical aspects, in particular the requirement for high pre-pulse contrast.
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Semin Vasc Surg, 2000
Diseases of the thoracic aorta pose a significant challenge to the surgeon because of the complex... more Diseases of the thoracic aorta pose a significant challenge to the surgeon because of the complexity of the disease and the characteristics of the patient population. Frequent comorbidities and increasing age account for mortality rates between 5% and 20% for surgical repair of descending thoracic aortic aneurysms and in excess of 50% for Stanford type B aortic dissections, when complicated by preoperative end-organ ischemia. Endovascular techniques of fenestration, stenting, and stent-grafting have emerged as viable alternatives to conventional surgery in these patients. The authors review their experience using endovascular stent-grafts in the treatment of 103 patients with descending thoracic aortic aneurysms and 19 patients with acute aortic dissections. Fenestration and stenting are also addressed as adjuvant therapies in the treatment of complicated aortic dissections. Actuarial survival for aneurysms was 81% +/- 5% at 1 year and 73% +/- 5% at 2 years. Stent-grafting for acute aortic dissections achieved instant relief of symptoms in 71% of cases with an early procedural mortality of 16%, and endovascular revascularization of ischemic beds was achieved in 93% +/- 4% of cases of peripheral or visceral ischemia. The authors' experience supports the use of endovascular techniques in the treatment of thoracic aortic pathologic conditions. Longer follow-up and results of ongoing trials that use newer devices will help define the indications for their future use.
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Journal of Cardiothoracic and Vascular Anesthesia, Sep 1, 2007
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Journal of Global Buddhism, 2012
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The Journal of Physical Chemistry, 1994
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The Journal of Thoracic and Cardiovascular Surgery, 2007
The RIFLE criteria are new international consensus definitions for acute kidney injury introduced... more The RIFLE criteria are new international consensus definitions for acute kidney injury introduced to facilitate research across disciplines. We identified risk factors for acute kidney injury, renal replacement therapy, and mortality using the RIFLE criteria (RIFLE = risk, injury, failure, loss, end stage) in patients undergoing deep hypothermic circulatory arrest for aortic arch reconstruction. A single-center retrospective cohort study of 267 patients undergoing aortic arch surgery with deep hypothermic circulatory arrest was conducted between July 2001 and October 2005. Known predictors (age, chronic kidney disease, surgery status, redo, diabetes, hypertension, blood transfusion, bypass, and deep hypothermic circulatory arrest time) were used in multivariate logistic regression models for acute kidney injury, renal replacement therapy, and mortality. Mean age was 64 years (range 23-89 years) with 166 men (62%). Seventy-five (28%) had RIFLE scores of I or F, and 22 (8%) required dialysis. Risk factors for acute kidney injury were hypertension (odds ratio [OR] = 2.17; 95% confidence intervals [CI], 1.14-4.15), chronic kidney disease (OR = 9.04; 95% CI, 1.97-41.59), packed red blood cells greater than 5 units (OR = 2.37; 95% CI, 1.20-4.69), and admission creatinine/Modification of Diet in Renal Disease predicted creatinine ratio greater than 1 (OR = 3.54; 95% CI, 1.95-6.45). Risk factors for mortality were age (per 10 years) (OR = 2.35; 95% CI, 1.35-4.06), AKI (RIFLE class R, I, or F) (OR = 4.60; 95% CI, 1.34-15.77), and cerebrovascular accident (OR = 19.1; 95% CI, 4.96-73.58). Mortality increased with each RIFLE stratification (RIFLE class 0 = 3%, R = 9%, I = 12%, and F = 38%). Acute kidney injury as defined according to the RIFLE classification is a risk factor for mortality and will be useful in future studies of renal dysfunction in thoracic aortic surgery.
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The Annals of Thoracic Surgery, 2004
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The Journal of Thoracic and Cardiovascular Surgery, Aug 31, 2009
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Plastic and Reconstructive Surgery, Jun 1, 2007
Current theory on normal cranial suture fusion entrusts the dura with the regulatory role. Studie... more Current theory on normal cranial suture fusion entrusts the dura with the regulatory role. Studies suggest that the dura responds to stress with changes in gene expression. Noggin (bone morphogenetic protein inhibitor) expression is decreased in normal (rat and mouse) cranial suture fusion, but its role in craniosynostosis and the response to stress has not been studied. Posterior frontal (fusing) and sagittal (patent) rat cranial sutures were held static, oscillated, or distracted for 10 days in an organ culture microdistraction device beginning at 5 days of age (n = 30 sutures, or 10 sutures per group). The percentage of fusion equaled the score received for bony closure. Noggin, Runx2, and alkaline phosphatase expression was localized by immunohistochemistry for all groups. Both the posterior frontal and sagittal sutures demonstrated a significant (p < 0.05) increase in fusion percentage with oscillation relative to the static control. Noggin was not expressed in the fusing posterior frontal suture but was expressed in the normally patent sagittal suture. Conversely, Runx2 was expressed in the posterior frontal suture but not in the sagittal suture. However, when a mechanical stress was applied, both the posterior frontal and sagittal sutures expressed Runx2 but not Noggin, as in the static fusing suture. The application of mechanical stress to cranial sutures results in fusion of both the posterior frontal suture and the normally patent sagittal suture. Runx2 is expressed but Noggin is not expressed. Thus, mechanical stress influences sutural fusion and may play a role in craniosynostosis.
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The Journal of Physical Chemistry B, Sep 1, 2003
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Cardiol Clin, 1999
ABSTRACT Technology is proceeding at a very brisk pace. Harnessing that technology for clinical u... more ABSTRACT Technology is proceeding at a very brisk pace. Harnessing that technology for clinical use is both a challenge and an opportunity. This combination of surgical and interventional methods has allowed for improved clinical outcomes in certain complex aortic problems. This article explores and discusses new techniques used in detection and treatment of diseases of the thoracic aorta.
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Journal of Vascular Surgery, Feb 1, 1997
Purpose: Patients with aneurysmal disease involving both the descending thoracic and abdominal ao... more Purpose: Patients with aneurysmal disease involving both the descending thoracic and abdominal aorta have historically required simultaneous or sequential conventional operations, but the morbidity rate is high with either approach in these patients, who often exhibit coexisting cardiopulmonary disease. Transluminally placed endovascular grafts have recently been developed for repair of aortic aneurysms, and we have implemented these techniques to eliminate the need for a thoracotomy in patients with multilevel aortic disease.Methods: Since January 1994, 18 patients have undergone conventional abdominal aortic replacement with endovascular stent-graft placement into the descending thoracic aorta under fluoroscopic guidance through a 10 mm Dacron side limb off the abdominal graft. Abdominal aortic replacement required a tube graft in eight patients and bifurcated grafts in 10 patients. Thoracic stent-grafts (custom fabricated, woven Dacron covered, self-expandable stents) averaged 12.2 ± 4.2 cm (mean ± SD) in length.Results: One patient died, resulting in a hospital mortality rate of 6%. No patients required further surgical intervention to treat their aortic disease. Seventeen patients (94%) are currently well 14 ± 8 months after surgery (range, 3 to 29 months) with completely excluded thoracic aortic disease, no stent migration, and no change in stent configuration documented by serial radiologic examinations.Conclusions: Simultaneous abdominal aortic replacement and deployment of a thoracic stent-graft can safely exclude multilevel aortic aneurysmal disease and may be a valuable treatment option for these otherwise high-risk patients. (J Vasc Surg 1997;25:332-40.)
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The Annals of Thoracic Surgery, Jun 1, 1999
Objective. The feasibility and efficacy trial of an endovascular stent-grafting system for the tr... more Objective. The feasibility and efficacy trial of an endovascular stent-grafting system for the treatment of aneurysms of the descending thoracic aorta was investigated.Methods. After Institutional Review Board approval, 103 patients (mean age 69 years) underwent stent graft repair of a descending thoracic aortic aneurysm between July 1992 and November 1997. The stent graft was fabricated using self-expanding “Z” stents covered by a woven Dacron tube graft. Follow-up, which averaged 22 months, was 100% complete. Simultaneous open abdominal aortic aneurysm repair was performed in 19 patients.Results. Complete aneurysm thrombosis was achieved in 86 patients (83%). Early mortality, defined as a death during the same hospitalization or in less than 30 days, was 9 ± 3%, and was significantly associated with preoperative cerebrovascular accident (CVA) or myocardial infarction. Major perioperative morbidity occurred in 31 patients, and included paraplegia in 3, CVA in 7, and respiratory insufficiency in 12 patients each. Actuarial survival was 81 ± 4% at 1 year, and 73 ± 5% at 2 years. Treatment failure (including all late, sudden, unexplained deaths) occurred in 38 patients, and only 53 ± 10% of patients were free of treatment failure at 3.7 years. Five patients required late operative therapy for endoleaks associated with aneurysm enlargement.Conclusions. Satisfactory results were achieved using this “first-generation” homemade stent graft device. Mortality and morbidity occurred frequently, but may have been associated with the high-risk character of this patient population. Medium-term results were acceptable, but continued aortic enlargement, with the late development of endoleaks, is a significant concern. Second-generation devices with commercial development, coupled with this initial experience, should allow improved clinical results in the future. Longer term follow-up is still necessary to fully define the efficacy of this endovascular approach.
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J Vasc Surg, 1993
Intravascular ultrasonography, balloon angioplasty, stent placement, and endovascular septal fene... more Intravascular ultrasonography, balloon angioplasty, stent placement, and endovascular septal fenestration have been used in the evaluation and treatment of vascular complications of acute and chronic aortic dissection in five patients. There were three men and two women with an average age of 52 years (range 39 to 64 years). There were three chronic type A dissections, one acute type B, and one subacute type B dissection. Intravascular ultrasonography was used in all five cases. The three patients with chronic type A dissections underwent unilateral renal artery angioplasty (RA PTA) and stent placement; one patient with an acute type B dissection and associated fibromuscular dysplasia underwent bilateral RA PTA without stent placement. These procedures were performed to ameliorate severe hypertension. The final patient, with a subacute type B dissection, underwent iliac artery stenting to correct severe lower extremity ischemia. During a second intervention, this patient, who also had bowel ischemia and nonresolving acute renal failure, underwent balloon dilatation of a preexisting septal fenestration to augment visceral blood supply and bilateral RA PTA and stent placement in an effort to improve renal function. This patient eventually died of gut ischemia. After RA PTA and stent placement, one patient had a major intrarenal hemorrhage that required coil embolization and transfusion. In the four survivors, RA PTA and stent placement resulted in immediate improvement in blood pressure control. This response has been sustained during follow-up intervals ranging from 8 to 18 months (average 10 months). Intravascular ultrasonography can clearly demonstrate the pathologic anatomy associated with aortic dissection (even when angiography is ambiguous) and is essential for guiding therapeutic endovascular interventions. Further exploration of the efficacy of these endovascular techniques is warranted in this high-risk group of patients with aortic dissection who have appropriate clinical indications.
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