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Biomedical subjects

S Wallace

Publications and source records attributed to S Wallace.

At least 505 records · Page 28Linked to original sources

A large lumen microcatheter for oncologic intervention.

A newly available Tracker-325 catheter (Target Therapeutics, Fremont, CA, USA), modified from the Tracker-18 catheter, has the same outer diameter but a larger lumen. This catheter was used in 15 patients during a 7-month period for superselective arterial catheterization when conventional catheters could not be placed successfully. Arterial embolization (n = 7), chemoembolization (n = 5), and chemoinfusion (n = 3), were performed. The increased luminal diameter of the Tracker-325 allowed an increased flow rate for diagnostic arteriography, accommodated larger embolic particles, and improved the ability to achieve a super-selective position.

Angiography↗

Hepatic artery infusion and chemoembolization in the management of liver metastases.

Hepatic metastases rather than the primary neoplasm usually dictate the course of the disease and patient's survival. For unresectable disease, intraarterial infusion of chemotherapy, embolization, and chemoembolization are viable alternatives. Intraarterial therapy for hepatic metastases is based on the dual blood supply of the normal liver (portal vein, 75%, and hepatic artery, 25%) and that of the tumors (hepatic artery, 90%). Intraarterial infusion delivers a higher concentration of chemotherapy, whereas chemoembolization adds ischemia and increased contact time with the tumor. Selective vascular occlusion for infusion, redistribution of the blood supply and pulsatile flow enhance the delivery of therapeutic agents to the liver.

Antineoplastic Agents↗

Experimental evaluation of ethanol-ethiodol for transcatheter renal embolization.

Adult mongrel dogs were used to evaluate and compare the use of ethanol and ethanol-Ethiodol for transcatheter renal arterial embolization. Each agent was administered into a main renal artery in five dogs and evaluated with regard to ease of use, radiopacity, arterial occlusion, parenchymal damage, and toxicity. Both agents were easy to inject, and no complications were encountered in any of the animals. Ethiodol added the ability to fluoroscopically monitor the infusate for reflux and distribution, yielded a more homogeneous distribution of the ethanol within the renal vasculature, and increased the embolic effects of the ethanol. Adding Ethiodol to ethanol should decrease the latter's complications since administration can be monitored fluoroscopically and a smaller volume of ethanol could perhaps be used to achieve the desired result. Additional research is needed to determine the safety of administering larger volumes of Ethiodol into the renal artery.

Animals↗

Occlusive effect of metallic stents on canine ureters.

A three-part study, with successive modifications based on preceding results, was conducted to evaluate ureteral placement of metallic stents. Gianturco self-expanding (10 mm and 4 mm diameter) and balloon-expanded (4 mm diameter) metallic stents were placed in normal and stenotic canine ureters. No migration or ureteral perforation occurred during the follow-up of 10 mm stents. Varying degrees of hydronephrosis and hydroureter were found on all 1-week pyelograms. At 4 weeks, complete occlusion of the stented ureter was noted in all cases because of mucosal hyperplasia around the stent wires. To prevent this reaction, 4 mm self-expanding stents constructed of smaller wire that was uncoated or coated with either Teflon or poly-urethane were tested in five dogs. In all cases, results were similar to those obtained with the larger prostheses. Finally, 4 mm balloon-expanded stents were placed in a normal ureter of three dogs. In one dog, the stent migrated out of the ureter. No migration or ureteral perforation occurred in the two remaining dogs. In these animals, mucosal hyperplasia and complete ureteral occlusion occurred 6 and 8 weeks after placement. Therefore, ureteral placement of Gianturco self-expanding as well as balloon-expanded metallic stents leads to occlusion of the ureter instead of maintaining its patency. Stents, therefore, may be useful as ureteral occlusion devices.

Animals↗

Monodisk: device for percutaneous transcatheter closure of cardiac septal defects.

The Monodisk, a device to facilitate percutaneous closure of cardiac septal defects, was developed and tested in vitro and in vivo. Atrial septal defects (8-10 mm) were created in five dogs using transcatheter techniques. The defects were then closed with the Monodisk. The device was easily and successfully fixed in place in all dogs. The efficacy of the device was determined radiographically. No shunting of contrast medium was observed in any case. Animals were followed for 6 months. Results showed good biocompatibility and several advantages of the device: it requires only a simple one-step placement procedure; it utilizes a small delivery system; it is easy to place and detach; it is self-centering and stable; and it can be repositioned or retrieved prior to detachment. Its possible clinical applications include correction of atrial septal defects, ventricular septal defects, patent ductus arteriosus, as well as creating an aortopulmonary window.

Animals↗

Percutaneous biopsy.

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Biopsy, Needle↗

Percutaneous lymph node biopsy.

Advances in imaging modalities for detecting lymphadenopathy, the ease, safety, and accuracy of the tools and techniques, and the addition of refined ancillary studies for cytologic analysis will continue to increase the acceptance and use of percutaneous lymph node biopsy (PLNB) by fine-needle aspiration (FNA), especially in lymphomas.

Biopsy, Needle↗

Percutaneous skeletal biopsy.

Percutaneous bone biopsy has become an accepted means for tissue diagnosis in indeterminate metastatic disease, whereas needle biopsy for the evaluation of primary skeletal neoplasms is controversial. Needle biopsies are also of value in the diagnosis of inflammatory lesions and eosinophilic granuloma. The diagnostic accuracy of this procedure ranges from 50 to 94% in malignant disease, but is less favorable in benign disease. The low complication rate of about 0.2% makes the percutaneous approach an attractive alternative to surgical biopsy.

Biopsy, Needle↗