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David S Wang

Publications and source records attributed to David S Wang.

14 recordsLinked to original sources
PubMed2006

Will stent-graft repair emerge as treatment of choice for acute type B dissection?

Endovascular stent grafts are now accepted globally and approved by the US Food and Drug Administration as an alternative to open surgical repair for patients with descending thoracic aortic aneurysm. However, as opposed to the abdominal aorta, application of this technology to manage thoracic aortic disease is not limited to degenerative aneurysms. In fact, international registries and surveys estimate that only 60% of the thoracic cases managed currently with stent-graft placement are aneurysms. The remainder of this experience includes acute dissection, chronic dissection, traumatic aortic injury, penetrating ulcer, intramural hematoma, aortic fistula, anastomotic pseudoaneurysm, and an embolizing lesion. In this regard, it is important to keep in mind that the present devices used in these nonaneurysmal applications are not designed to address the unique anatomical and pathological features that these lesions present. Consequently, in the future, it is possible that we will see stent-graft designs that focus specifically on the challenges of some of the nonaneurysmal thoracic aortic pathologies.

Aged↗
PubMed2006

Molecular imaging: a primer for interventionalists and imagers.

The characterization of human diseases by their underlying molecular and genomic aberrations has been the hallmark of molecular medicine. From this, molecular imaging has emerged as a potentially revolutionary discipline that aims to visually characterize normal and pathologic processes at the cellular and molecular levels within the milieu of living organisms. Molecular imaging holds promise to provide earlier and more precise disease diagnosis, improved disease characterization, and timely assessment of therapeutic response. This primer is intended to provide a broad overview of molecular imaging with specific focus on future clinical applications relevant to interventional radiology.

Animals↗
PubMed2005

Correlation of preoperative three-dimensional magnetic resonance angiography with intraoperative findings in laparoscopic renal surgery.

BACKGROUND AND PURPOSE: Contrast-enhanced three-dimensional magnetic resonance angiography (3D-MRA) with image reconstruction has important applications in laparoscopic urologic surgery. We now use 3D-MRA as part of our preoperative evaluation in selected patients undergoing laparoscopic donor nephrectomy, pyeloplasty, radical nephrectomy, and partial nephrectomy. PATIENTS AND METHODS: From June 2001 to December 2002, 50 patients underwent preoperative 3D-MRA at 1.5 T prior to laparoscopic renal surgery. In general, preoperative 3D-MRA was obtained for donor nephrectomies and pyeloplasties and for cases where prior imaging suggested a possible vascular anomaly. Patients who underwent preoperative imaging included those having donor nephrectomy (N = 28), pyeloplasty (N = 12), radical nephrectomy (N = 5), partial nephrectomy (N = 3), and other laparoscopic renal procedures (N = 2). The 3D-MRA studies were interpreted by one radiologist, and all laparoscopic cases were performed by one of two surgeons. The findings of 3D-MRA were correlated with the intraoperative findings with special attention to aberrant vasculature, including duplicated renal arteries or veins, accessory vessels, or crossing vessels. RESULTS: Among patients undergoing laparoscopic donor nephrectomy, 3D-MRA correctly predicted the number of renal vessels in 27 of 28 cases (96%), including all 3 cases of left retroaortic renal vein. Also, 3DMRA correctly predicted the presence or absence of a crossing vessel in 10 of 12 cases (83%) of laparoscopic pyeloplasty. The imaging study also correctly predicted the number of hilar vessels in all five cases of radical nephrectomy, all three cases of partial nephrectomy, and both cases of other renal operations. Overall, 3D-MRA correctly defined the renal hilar anatomy in 48 of 50 patients, for an overall accuracy of 96%. CONCLUSIONS: Three-dimensional MRA findings correlate well (96%) with intraoperative findings in laparoscopic renal surgery. The imaging study provides exquisite vascular detail and is highly accurate, making it sufficient imaging prior to laparoscopic donor nephrectomy and useful for pyeloplasty and other complex renal operations.

Chelating Agents↗
PubMed2005

Directed migration of smooth muscle cells to engineer plaque-resistant vein grafts.

PURPOSE: To test the hypothesis that controlled perivascular release of tissue plasminogen activator (tPA) can generate cleaved extracellular matrix (ECM) chemotactic gradients to guide the migration of vascular smooth muscle cells (SMCs) away from the lumen, thereby limiting neointima formation. METHODS: This hypothesis was tested in rabbit models in which the perivascular surface of vein bypass grafts was treated with microspheres releasing tPA (MS-tPA), microspheres containing no drug (MS-blank), or phosphate buffered saline (PBS). Vein graft segments harvested after 7 days were then evaluated for elastin content, proliferating SMCs, intima-to-media (I/M) ratio, and inflammation; late impact on neointima formation was also examined. RESULTS: The 7-day results demonstrated cleaved elastin gradients and proliferating SMCs that assumed a more peripheral distribution in the MS-tPA group than MS-blank and PBS controls (p<0.05). At 28 days, vein grafts treated with MS-tPA showed a mean I/M ratio (0.35+/-0.04) that was 63.5% lower than PBS controls (0.96+/-0.07, p<0.005) and 43.5% lower than MS-blank specimens (0.62+/-0.08, p<0.05). CONCLUSIONS: Perivascular release of tPA modifies ECM gradients, directionally guides SMC migration away from the lumen, and limits neointima formation.

Analysis of Variance↗
PubMed2004

Hand-assisted laparoscopic right donor nephrectomy: surgical technique.

Many centers have adopted laparoscopic and hand-assisted laparoscopic (HAL) techniques for live donor nephrectomy. Currently, the majority of laparoscopic living donor kidneys are procured from the left side because of the longer renal vein and improved transplantation. However, indications exist for right donor nephrectomy. We present our technique of HAL right-sided donor nephrectomy. A key feature of our dissection is wide mobilization of adjacent structures to achieve good exposure of the right kidney and inferior vena cava. In addition, the use of the hand permits optimal positioning of the kidney for division of the renal vessels with the vascular stapler. At the time of division of the renal vein, the stapler is placed on the wall of the inferior vena cava in order to gain maximal length. This technique has allowed HAL right-sided donor nephrectomy to be performed safely when indicated.

Humans↗
PubMed2004

Use of bipolar energy for transurethral resection of bladder tumors: pathologic considerations.

BACKGROUND AND PURPOSE: Bipolar electrocautery has recently been introduced as a modality for transurethral resection of bladder tumors (TURBT). The primary benefits of bipolar TURBT stem from the use of saline irrigant rather than glycine or water. TURBT should be conducted in a fashion such that the resected tissue can be used for proper grading and staging, so excessive cauterization of the tissue should be avoided. In this study, we compared the pathologic characteristics of bladder tumor specimens resected with bipolar versus standard monopolar energy to determine specimen quality. PATIENTS AND METHODS: Bipolar TURBT (Gyrus Medical Inc., Maple Grove, MN) was performed in 11 patients. Pathologic specimens were compared with the specimens from 11 patients who had previously undergone standard monopolar TURBT. Resected tissue was examined by a pathologist who recorded tumor size, grade, location, presence of muscularis propria, presence of muscle invasion, and final diagnosis. The pathologist also determined the degree of cautery artifact in each specimen. The pathologist was blinded to the form of electrocautery used and the clinical diagnosis. RESULTS: Transurethral resection with bipolar electrocautery was carried out without difficulty or complication in all cases. Similarly, there were no complications in resection by standard monopolar electrocautery. The bladder tumor chips obtained with bipolar TURBT were smaller because of the smaller size of the bipolar loop. However, this did not interfere with the pathologic assessment. There were no significant pathologic differences between specimens according to the type of cautery used. A large degree of cautery artifact was noted in the tissue of larger tumors resected using both monopolar and bipolar electrocautery. However, the incidence and degree of cautery artifact were similar in the two groups. No trends between tumor location and degree of cautery effect were noted. The pathologist had no difficulty reaching a full and proper diagnosis in all cases involving either form of electrocautery. CONCLUSIONS: Bipolar electrocautery is well suited for TURBT. Bladder tissue obtained from bipolar TURBT is of the same histologic quality as that obtained from standard monopolar TURBT and provides the urologist with a reliable and complete diagnosis.

Electrosurgery↗
PubMed2004

Survey of urological laparoscopic practice patterns in the midwest.

PURPOSE: Laparoscopic surgery is assuming a greater role in the management of many urological disorders. We performed a survey of urologists in the Midwest United States to define laparoscopic practice patterns regarding urological disease. MATERIALS AND METHODS: Surveys were mailed to 1,450 members of the North Central Section of the American Urological Association. Questions pertained to age, practice demographics, residency training and amount of laparoscopy performed. RESULTS: A response rate of 33% was obtained. A total of 49% of urologists perform no laparoscopy, 30% devote less than 5% of their practice and 21% devote 5% or more of their practice to laparoscopy. Of the responders 15% believed they were adequately trained during residency to perform laparoscopy. Among those who performed hand assisted laparoscopy (HAL), 52% used it to gain familiarity with laparoscopic techniques. There was an inverse correlation between time in practice and amount of laparoscopy performed (p <0.0001). Urologists in academia perform laparoscopy at a greater proportion versus those in private practice (p <0.01). Urologists who incorporated laparoscopy during fellowship performed the most laparoscopy (p = 0.003). Those who considered themselves adequately trained during residency were more likely to perform laparoscopy (p <0.0001). Urologists who perform HAL devote more of their operating time to laparoscopy than those who do not (p <0.0001). The number of laparoscopic cases performed correlated with decreased time in practice (p <0.0001), academic setting (p = 0.001) and use of HAL (p <0.0001). CONCLUSIONS: Urological laparoscopic surgery remains at an early stage of development in the Midwestern United States. Although HAL has widened the scope of laparoscopy among urologists, increased training for urologists and residents is necessary.

Adult↗
PubMed2004

Local resistance to oxidative stress by overexpression of copper-zinc superoxide dismutase limits neointimal formation after angioplasty.

PURPOSE: To examine the effects of oxidative stress on neointimal hyperplasia through local overexpression of human copper-zinc superoxide dismutase (Cu-Zn SOD). METHODS: The left common femoral arteries (CFA) of 18 New Zealand white rabbits were subjected to balloon overdilation injury. Each dilated CFA was then incubated with either a nonviral (buffer) or viral (adenovirus overexpressing beta-galactosidase) control or an adenovirus overexpressing Cu-Zn SOD. Animals were then sacrificed at 3, 7, or 28 days (3 arteries per group per time point) and the treated CFA segments were harvested for analysis of esterase-positive inflammatory cells and extracellular matrix elements. The intima-to-media ratio (I/M) was measured to assess the degree of neointimal formation. RESULTS: At 3 days, local SOD levels in the Cu-Zn SOD-treated group were significantly elevated relative to both controls (p<0.01). Significant reductions in lipid peroxidation byproducts were also seen in the SOD group relative to viral and nonviral controls (p<0.05). Mean I/M at 28 days was 0.582+/-0.088 for the nonviral control group versus 0.565+/-0.133 for the viral control group. The SOD-treated group had a significant reduction relative to both controls: 0.259+/-0.045 (p<0.05). Statistically significant reductions in I/M were also demonstrated in the SOD group relative to control groups at 7 days (p<0.05). The SOD-treated group demonstrated significant preservation of elastin relative to controls, as well as a significant reduction in esterase-positive granulocytes relative to controls (p<0.05). CONCLUSIONS: Direct buffering of oxidative stress in balloon-injured vessels can significantly alter postinjury response and limit neointimal hyperplasia.

Angioplasty, Balloon↗
PubMed2004

Laparoscopic upper pole heminephrectomy for ectopic ureter: initial experience.

OBJECTIVES: To determine the feasibility, clinical outcomes, and complications of laparoscopic upper pole heminephrectomy for ectopic ureter. The standard treatment for a duplex kidney with a poorly functioning upper pole moiety is an upper pole heminephrectomy. We review our technique and experience with laparoscopic upper pole heminephrectomy. A brief review of the literature is provided. METHODS: A retrospective review of clinical records from three patients who underwent laparoscopic upper pole heminephrectomy was performed. Two of the three patients presented with lifelong urinary incontinence and were diagnosed with an ectopic ureter associated with a poorly functioning upper pole moiety. The third patient presented with recurrent episodes of pyelonephritis and was found to have a duplex kidney with a poorly functioning upper pole segment draining into a ureterocele. RESULTS: All three patients underwent laparoscopic upper pole heminephrectomy through the transperitoneal approach. Mean operative time, including ureteral stent insertion, was 198 minutes. Two of the three patients were discharged within 24 hours of surgery. The third patient had a urinary leak secondary to a small amount of residual upper pole parenchyma which resolved with superselective renal arterial embolization. All three patients are well at 5.3 months follow-up. CONCLUSIONS: Laparoscopic upper pole heminephrectomy for ectopic ureter is safe and reproducible and offers the patient the typical postoperative benefits of laparoscopic surgery.

Adolescent↗
PubMed2003

In-stent restenosis limitation with stent-based controlled-release nitric oxide: initial results in rabbits.

PURPOSE: To evaluate effect of controlled stent-based release of an NO donor to limit in-stent restenosis in rabbits. MATERIALS AND METHODS: 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. RESULTS: 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 <.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 <.01; 1.34 +/- 0.05 vs 1.98 +/- 0.08 at 28 days, P <.01). CONCLUSION: Stent-based controlled release of NO donor significantly reduces in-stent restenosis and is associated with increase in vascular cGMP and suppression of proliferation.

Angiography, Digital Subtraction↗
PubMed2003

A novel technique to prevent inadvertent sheath migration.

Inadvertent trocar-sheath migration is annoying to the surgeon and may result in serious visceral injury. Herein is described a novel technique to prevent such migration. A 0.25-in. Penrose drain is wrapped around the trocar-sheath unit as a collar to prevent sheath migration.

Foreign-Body Migration↗
PubMed2003

Laparoscopic upper-pole heminephrectomy for ectopic ureter: surgical technique.

A duplex kidney associated with a poorly functioning upper-pole segment is commonly associated with incontinence, voiding dysfunction, and urinary tract infections. A standard treatment option for this condition is upper-pole heminephrectomy. With the continued development of minimally invasive urology, this technique can now be safely performed laparoscopically. This report details step by step our technique of laparoscopic upper-pole heminephrectomy. Key points include placement of a catheter in the normal ureter at the start of the case, full mobilization of the upper-pole ureter away from the renal hilum, and precise identification of the vasculature supplying the upper pole. Laparoscopic upper-pole heminephrectomy for ectopic ureter is safe and reproducible and offers the patient the typical postoperative benefits of laparoscopic surgery.

Humans↗
PubMedDate not supplied

Laparoscopic ureterolysis for benign and malignant conditions.

Ureteral obstruction secondary to extrinsic compression is uncommon. Extrinsic compression results from both benign and malignant conditions of the retroperitoneum. In certain patients, laparoscopic ureterolysis is a minimally invasive alternative to the open approach. To date, the largest numbers of patients have undergone this procedure for idiopathic retroperitoneal fibrosis. Select patients with ureteral obstruction following cancer chemotherapy or radiotherapy may also be candidates for laparoscopic ureterolysis, although experience is limited. This article reviews the current indications, technique, and results of laparoscopic ureterolysis for both benign and malignant conditions. Further long-term studies are required to define its role.

Female↗