C Gianturco

MECHANICAL DEVICES FOR ARTERIAL OCCLUSION

Two mechanical devices for the purpose of occluding vessels are presented.Cotton tails, small metallic segments with attached cotton threads, will effectively occlude small arteries of approximately 2 mm. in diameter.Wool coils, 5 cm. segments of the outer portion of steel guidewires with attached wool strands, obstructed major vessels just beyond the tip of the catheter.The use of these devices has been investigated in dogs and then applied clinically in the occlusion of renal arteries in patients with hypernephroma.

Transcatheter occlusion of abdominal tumors.

Radiological and clinical experience with transcatheter intravascular occlusion of abdominal and pelvic tumors in 55 patients is presented. Major indications include control of hemorrhage, palliation of local tumor symptoms, and preoperative management of facilitate surgery. Methods of occlusion included embolization (clot, subcutaneous tissue, and Gelfoam), introduction of a stainless steel coil into larger vessels, and balloon catheters. Hemorrhage was controlled in 8 of 12 patients with bleeding gastrointestinal and pelvic tumors. Experience in 36 patients with hypernephroma is discussed. Initial observations are presented, including occlusion of the hepatic artery for dearterialization of primary and secondary neoplasms and of the splenic artery for hypersplenism.

“Mini” Gianturco Stainless Steel Coils for Transcatheter Vascular Occlusion

Small stainless steel coils have been developed for transcatheter vascular occlusion procedures. The coils can be passed through a 5-French polyethylene catheter, extending the clinical applications of coil occlusion procedures for small and/or tortuous vessels. Two cases describing the use of these coils are reported.

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 the patients 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.

The Use of Prostaglandin E1 to Enhance the Angiographic Visualization of the Splanchnic Circulation

Superior mesenteric angiograms were obtained in a series of dogs before and again after the injection of a 1-ml bolus of prostaglandin E1 (0.1-1.0 mug/kg) through the angiographic catheter. The prostaglandin E1 produced, on the average, a 100% increase in the superior mesenteric arterial blood flow with only minimal changes in the heart rate, systemic arterial pressure, and portal venous pressure. Opacification of the portal venous system was consistently enhanced after the prostaglandin E1. The arterial phase was preserved by increasing the rate of contrast administration.

Experimental transcatheter intraarterial infusion-occlusion chemotherapy.

Dogs were used to develop transcatheter vascular techniques to improve local tissue accumulation of a radiolabeled chemotherapeutic agent. A double lumen balloon catheter was used for short term (10 minute) intraarterial infusions of 14C labeled Fluorouracil (5-FU) during temporary vascular occlusion with the balloon. Local tissue (hind limb musculature) as well as venous blood concentrations of 5-FU draining the area of infusion were compared to those obtained following intraarterial infusion alone or following intravenous administration of the drug. Combining intraarterial infusion with temporary vascular occlusion increased (7 to 9 times) the local tissue concentration of the 5-FU when compared to intraarterial infusion alone. The local tissue levels of the drug during intraarterial infusion and temporary vascular occlusion were 30 to 50 times greater than those obtained by intravenous administration. Levels of 5-FU were also significantly higher in the venous blood draining the infusion area when the combined intraarterial infusion-occlusion technique was employed.

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 polyurethane 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.

Treatment of experimentally induced atherosclerosis in swine iliac arteries: A comparison of self-expanding and balloon-expanded stents

Atherosclerosis was induced in 20 Hanford miniature swine. Subsequently, one iliac artery lesion in each of 16 pigs was stented with either a self-expanding (8 pigs) or a balloon-expanded (8 pigs) stent. Immediately after stent placement, 4 animals in each group were taken off the atherogenic diet and continued on normal chow for the remainder of the study. Four months after stents were placed, atherosclerosis and the mural changes associated with the stent were more clearly evident in the arteries of the pigs continued on the atherogenic diet. These pigs also exhibited significantly more neointimal proliferation. In addition, the arteries containing the balloon-expanded stents showed more extensive and complex intimal changes when compared with arteries with self-expanding stents. Although both stent designs were equally effective in maintaining vascular patency, the balloon-expanded stent was more traumatic to the vessel wall which resulted in a significantly greater neointimal thickness.

A Scanning Electron Microscopic Study of Angiographic Catheters and Guide Wires

The scanning electron microscope was used to study the surface characteristics of angiographic catheters and guide wires. All catheter surfaces examined exhibited manufacturing imperfections such as fissures, depressions, protrusions, and scratches. The external surfaces of stainless steel and Teflon-coated guide wires vary according to the manufacturing process. Guide wires cleaned after clinical use show retention of blood elements and debris. It is recommended that a new guide wire be employed for each patient.

Anticoagulation Techniques for Angiography An Experimental Study

Light and scanning electron microscopy were used to show thrombus formation on an experimental model, a guide wire-catheter assembly, after intravascular placement in a dog. The experimental model was tested prior to and following systemic heparinization and/or benzalkonium chloride-heparin coating. Clot deposition occurred within ten minutes of intravascular exposure without any form of anticoagulation. Employment of benzalkonium chloride-heparin-coated guide wires or systemic heparinization greatly decreased the formation of clot. It is recommended that an anticoagulant technique be employed during clinical angiography.