Kenneth C. Wright

Use of the Gianturco self-expanding stent in stenoses of the superior and inferior venae cavae.

Twenty-eight patients with severe superior and inferior vena cava syndromes were treated with self-expandable Gianturco stents. Nineteen patients responded, seven did not respond, and two were unevaluable. Fourteen of the 19 who responded had complete or near complete resolution of their syndrome, and five had a partial remission. Five of the responders did not derive any benefit from stent placement because of additional problems that led to their death within 3 weeks of the stent placement procedure. The main cause for failure was the relatively weak expansile force of the stent. Complications included stent migrations without untoward effects in one patient, stent misplacement in one patient, fracture of the stent wire in two patients, and hemorrhage that could be attributed to the stent in one patient. This uncontrolled study suggests that caval obstruction syndromes in some patients may be effectively palliated with Gianturco stents.

Role of Kupffer cells in iodized oil embolization.

RATIONALE AND OBJECTIVES.Iodized oil is a common oily embolic agent used in chemoembolization for treating hepatic tumors. However, how the iodized oil is cleared from the liver has been an unsettled and controversial issue. In this study, the authors attempt to clarify whether Kupffer cells are involved in the clearance of iodized oil and to evaluate the effect of hepatic arterial injection of iodized oil on the functional status of Kupffer cells. METHODS.Iodized oil was injected into the proper hepatic artery in 42 Fischer 344 rats. In vivo microscopy was performed immediately after and 1,3,7,15,30, and 60 days after injection. Electron microscopy was performed after in vivo microscopy. RESULTS.Kupffer cells actively captured and phagocytosed iodized oil droplets in the hepatic circulation. The number and functional status of Kupffer cells in the liver were significantly increased after the injection of the iodized oil and returned to normal when the liver was cleared of the oil. CONCLUSIONS.Kupffer cells play an important role in clearing iodized oil from the liver. Iodized oil activates the immune defense system in the liver, which may have a synergistic effect in tumor treatment.

Experimental evaluation of cellulose acetate NF and ethylene-vinyl alcohol copolymer for selective arterial embolization.

PURPOSEnStudies were conducted in rabbits to evaluate two new liquid polymeric compounds developed for selective arterial embolization.nnnMATERIALS AND METHODSnThe compounds consisted of cellulose acetate NF (Embolyx C) or ethylene-vinyl alcohol copolymer (Embolyx E) dissolved in anhydrous dimethyl sulfoxide (DMSO) containing 30% tantalum powder. Acute renal embolization was performed to determine an optimal method of administration and level of embolization. Kidneys were embolized with and without flow around the catheter. DMSO was also injected in the same manner. Tissue sections were examined radiographically and microscopically. Tumor embolization was performed to evaluate the efficacy of the polymers and compare their embolic effects with polyvinyl alcohol (PVA) particles and gelatin sponge (Gelfoam) powder. An embolic agent, saline, or DMSO was injected into the deep femoral artery feeding an intramuscular VX2 carcinoma. Animals were followed up for 3 weeks.nnnRESULTSnViscosity and administration technique affected polymer distribution and depth of penetration. Embolization with the test polymers was quicker and more easily achieved than with PVA or Gelfoam, and no recanalization occurred. Both polymers were as effective as PVA particles for tumor ablation, but DMSO caused some vascular damage.nnnCONCLUSIONnAlthough use of DMSO has some drawbacks, the results of this study warrant further investigation of the Embolyx polymers for tumor embolization.

Placement of Covered Self-Expanding Metallic Stents in the Common Bile Duct: A Feasibility Study

PURPOSEnGianturco self-expanding metallic stents have been useful in cases of benign biliary stenoses; however, the stents have not worked well in the presence of intraluminal tumor because of tumor growth between the wire struts. Stents were covered with polymeric membranes, which may prevent tumor ingrowth, and the feasibility of using these covered stents in the common bile duct was studied in healthy adult dogs.nnnMATERIALS AND METHODSnInitially, stents (10 x 6 mm) covered with polycaprolactone (PCL), segmented polyether polyurethane (SPP), and silicone were placed in the common bile duct of dogs and were followed up for 3-12 months. Subsequently, four types of modified silicone-covered stents were evaluated. Rough-surface, small-diameter (3-mm), half-covered, and tapered stents were placed and followed up for 3 months.nnnRESULTSnIn the initial study, the SPP and silicone membranes remained intact, but the PCL covering broke in all dogs. In all but two dogs, luminal narrowing caused by varying degrees of papillary mucosal hyperplasia at both ends of the stent was observed. In the subsequent study, mucosal hyperplasia was considerably reduced by using half-covered stents and was virtually eliminated with tapered stents. All small-diameter stents migrated into the bowel.nnnCONCLUSIONnThese studies suggest that tapered Gianturco self-expanding stents covered with silicone may be useful in the biliary tract in cases of intraluminal tumor.

Pulsed arterial infusions. Chemotherapeutic implications.

To simulate the intra‐arterial infusion of chemotherapy, ink was infused at a steady rate through a vascular catheter inserted in a transparent tube carrying water at a rate similar to that of arterial blood. The ink ran in one or two discrete streams for 10 to 15 cm before mixing with the water, and there were substantial differences in the concentrations of ink in the water collected from side holes made at various distances from the catheter tip. If the ink was delivered in short pulses, however, it mixed with the water 2 to 3 cm beyond the catheter tip, and the samples collected from the side holes showed similar concentrations of ink. A similar situation may be encountered when chemotherapeutic agents are infused into patients. Therefore, pulsation may produce a more homogeneous drug distribution in the infused tissue. The in vitro data was substantiated in patients by the following: (1) the intra‐arterial administration of technetium 99m(99MTc)labeled macroaggregated albumin (MAA) by both steady and pulsed infusions; and (2) changes in the severity of inflammatory skin reactions frequently associated with intra‐arterial chemotherapy of the extremities. Improved isotope distribution was noted in 19.3% of the liver and 40% of the extremity studies. Reduced skin reactions were observed in approximately 90% of the extremities receiving pulsed chemotherapeutic infusions.

A New Device for Transcatheter Closure of the Patent Ductus Arteriosus: A Feasibility Study in Dogs

A new device for transcatheter closure of the patent ductus arteriosus was developed and initially evaluated in the vasculature of adult mongrel dogs. The device consists of a nylon sack that can be made in various sizes and shapes. A small flexible crossbar attached to the distal end maintains the position of the sack while it is filled with a segment of modified guide wire. The device is delivered coaxially through a 10-Fr Teflon catheter and is easily repositioned or retrieved before release. The expansile force of the sack against the vessel wall can be varied, and its stability is easily checked prior to detachment. The device produced immediate and permanent vascular occlusion without inflammation or erosion. Over time, the entire unit became incorporated into the vessel wall by neointimal encasement. Nylon sacks offer a simple, unique method of closing virtually any ductus arteriosus without general anesthesia and major surgery.

Microcapsules for arterial chemoembolization: appearance and in vitro drug release characteristics

Microcapsules made of eight different capsular materials and containing floxuridine (FUDR) were formulated and evaluated with regard to physical properties (size and structure) and in vitro drug release characteristics. Capsules averaged 100, 150 and 200 micron in diameter and appeared as either round or crystalline particles. The degree and pattern of drug release was dependent on the capsular material used. Alteration in the molecular architecture of a specific material produced changes in the percentage of total encapsulated drug released per unit of time, but not in the pattern of release. Changing capsular size or amount of drug contained within the capsules failed to alter either the pattern of drug release or the percentage of encapsulated drug released per unit of time. However, changes in either parameter did affect the total amount of drug released per unit of time.

Anchoring Coil Embolization in a High-Flow Arterial Model: A Pilot Study☆

PURPOSEnTo devise and test an occluding coil anchoring system to improve the safety of coil embolization.nnnMATERIALS AND METHODSnThe anchoring system was attached to Gianturco embolization coils and investigated in 15 pigs. In the short-term studies, one 0.035-inch anchored coil (15-18 cm in length and 7-10 mm in diameter) was placed in the infrarenal portion of the abdominal aorta in each of 12 pigs with use of an 8-F catheter from the carotid approach. Aortography was performed before and up to 4 hours after coil placement. In the long-term studies, 0.028-inch anchored coils (8 cm in length and 5 mm in diameter) were placed in the left femoral and the right carotid arteries in each of three pigs with use of a 6-F catheter positioned from the right femoral approach. One week later, the animals were evaluated angiographically for coil migration and vascular occlusion.nnnRESULTSnRadiographically, the coils created a compact conglomerate on placement in all but one of the animals. No coil migration was noted during follow-up. Necropsy confirmed compact arrangement of the coils within the vessels and revealed effective anchoring of the device in all cases.nnnCONCLUSIONSnThe anchoring coil has proved effective in making coil embolization safer, especially in a high-flow arterial model.

Preliminary Results with a New Vascular Basket Occluder in Swine

PURPOSEnTo experimentally evaluate a new self-anchoring vascular occlusion device suitable for use in large, high-flow vessels.nnnMATERIALS AND METHODSnA basket-shaped occluding device consisting of a nitinol frame (with or without polyester threads) covered with Dacron was evaluated in the common iliac arteries and abdominal aortae of normal pigs. One occluder was placed in each recipient vessel. Angiography was performed before and after placement of each occluder.nnnRESULTSnPrecise placement of the device was achieved in all cases. Mechanically, all but one occluder worked dependably. Angiographically, devices without polyester threads produced only partial occlusion. Devices with threads produced complete occlusion in all but one abdominal aorta, in which partial occlusion occurred because the occluder opened asymmetrically. Complete iliac arterial occlusion occurred within 2-8 minutes of placement and aortic occlusion was achieved within 8-20 minutes. At necropsy, all devices were found to be securely anchored against the vascular wall.nnnCONCLUSIONnPreliminary results indicate that this vascular basket occluder containing polyester threads is easy to place precisely, produces rapid embolization, and demonstrates good self-anchoring ability in a high-flow arterial model.

Percutaneous intratumoral injection of cisplatin microspheres in tumor-bearing rats to diminish acute nephrotoxicity.

Poly(o,L-lactlde) microspheres loaded with cisplatin (PLA-CDDP MS) were prepared by a solvent evaporation technique for direct Intratumoral ln|ectlon. The microspheres, 50-100 |im, containing 40.04% of cisplatin produce sustained release In vitro. PLA-CDDP MS (6 mg/kg body weight of cisplatin) suspensions were Injected Intratumorally Into mammary tumors In rats. Cisplatin solution (6 mg/kg body weight) was Injected either Intratumorally or Intraperltoneally In two groups. After treatments, the tumor size decreased In each of the groups as a function of time. Sixteen days post-Injection, the tumors had either disappeared or significantly shrunk. PLA-CDDP MS had a similar antltumor effect compared with cisplatin aqueous solution. Blood urea nitrogen, serum creatlnlne and hlstopathology examinations revealed that the renal toxlclty In the PLA-CDDP MS group was significantly less than In the control groups. These results indicate that intratumoral injection of PLACDDP MS maintains antlcancer potency and reduces acute renal toxlclty.