Abdominal wall hernia repair: use of the Gianturco-Helfrich-Eberbach hernia mesh.

A new polyester hernia mesh (Gianturco-Helfrich-Eberbach) is introduced for laparoscopic repair of the abdominal wall and groin hernias. The device incorporates the optional use of an internal wire to form a circular shape. A detachable carrier is used, permitting easy, accurate preperitoneal placement. Thirty-four patients with groin hernias and five with ventral hernias were repaired without significant complication. This innovative device greatly facilitates mesh placement during transabdominal or extraperitoneal laparoscopic repair, reducing technical difficulty and operative time. It further broadens the use of laparoscopy to repair ventral hernias.

New Gianturco-Grifka vascular occlusion device. Initial studies in a canine model.

BACKGROUND: Transcatheter closure of cardiovascular defects remains a challenge. Several occlusion devices are available, but each device has limitations. The purpose of this study was to evaluate the new Gianturco-Grifka vascular occlusion device (GGVOD) in a canine model. METHODS AND RESULTS: A total of 26 GGVODs were implanted as part of short- and long-term studies. In the short-term study, 1 GGVOD was implanted in each of 11 systemic arteries from 3.2 to 9.0 mm in diameter. All 11 arteries were occluded immediately. In the long-term study, an aortopulmonary shunt was placed in 10 dogs (9, Gore-tex graft; 1, subclavian artery) followed by GGVOD implantation; additionally, a GGVOD was implanted in 5 subclavian arteries. The dogs were boarded for 3 to 6 months, then recatheterized and euthanatized. Immediately after implantation, the 5 subclavian arteries and 9 Gore-tex shunts were occluded completely; the 1 subclavian artery shunt had a small residual leak. At recatheterization, all 10 shunts and 5 subclavian arteries were occluded completely. Necropsy revealed all shunts to be occluded, with the aortic and pulmonic orifices covered with a neointimal layer. The mean fluoroscopic time needed for GGVOD implantation was 9 minutes (range, 3 to 22 minutes). CONCLUSIONS: (1) In a canine model, the GGVOD is effective for transcatheter occlusion of arteries and aortopulmonary shunts from 3 to 9 mm in diameter. Possible indications in children include aortopulmonary collateral vessels, long patent ductus arteriosus, systemic-pulmonary shunts, AV malformations, and arteries supplying tumors. (2) GGVOD implantation requires a short fluoroscopic time.

Placement of covered self-expanding metallic stents in the common bile duct: a feasibility study.

PURPOSE: Gianturco 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. MATERIALS AND METHODS: Initially, 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. RESULTS: In 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. CONCLUSION: These studies suggest that tapered Gianturco self-expanding stents covered with silicone may be useful in the biliary tract in cases of intraluminal tumor.

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.

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.

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.

Prostatic urethra dilatation with the Gianturco self-expanding metallic stent: a feasibility study in cadaver specimens and dogs.

In an effort to develop a transcatheter technique for dilatation of the prostatic urethra without the use of balloons, the feasibility of using Gianturco self-expanding stents was evaluated. Initially, eight human cadaveric prostatic urethras were stented to evaluate the ability of the stent to dilate the lumen. In all cases, the device attained its unconstrained diameter immediately on placement. Subsequently, stents were placed in the prostatic urethra of 12 dogs and followed up for 1 month (four dogs), 3 months (one dog), and 6 months (seven dogs). Five bare straight-end prostheses, one nylon-covered straight-end device, and six flared-end stents were used. Three of the bare straight-end stents migrated during the follow-up, whereas the nylon-covered and flared-end stents did not. Stent diameters greater than 1.3 times the urethral diameter caused moderate to marked edema and inflammation. After 6 months, white deposits were found on the solder points, presumably from electrolysis. Our experience suggests that placement of Gianturco self-expanding stents may be a useful method of dilating and maintaining the luminal diameter of the prostatic urethra, although care must be taken to select the proper stent size.

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.

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.

Percutaneously placed endovascular grafts for aortic aneurysms: feasibility study.

This limited study addressed the feasibility of treating aneurysms with a new transcatheter endoprosthesis. Aortic aneurysms were experimentally created in six dogs and subsequently bridged with nylon-covered, self-expanding metallic stents. The dogs were followed up for as long as 7 months (median, 22 weeks). In each dog, the graft effectively reconstituted the aortic lumen, excluding the aneurysm. One dog exhibited minimal (less than 1-mm) residual dilatation at the site of the aneurysm 7 months after graft placement. The nylon material acted as a support and template for neointimal encasement, enabling the formation of a new vascular lumen. It also remained porous at the origin of aortic side branches, preserving the visceral blood supply. One of the endovascular grafts failed to expand completely at its distal end, which promoted thrombus formation within the graft and resulted in the occlusion of both renal arteries. The dog was found comatose 48 hours after graft placement and was killed at that time.

Self-expanding endovascular graft: an experimental study in dogs.

An arterial endovascular graft was constructed by wrapping an expandable nylon mesh around a framework of Gianturco self-expanding metallic stents. The devices were passed through a 12-French Teflon catheter and positioned in the normal abdominal aorta of five dogs, two of which also had a device placed in an external iliac artery. At follow-up (1-6 months), all grafts remained patent, even though slight luminal narrowing due to neointimal encasement was noted. Histologically, all grafts were covered by neointimal proliferation at the time of removal. The graft material expanded with the stents, resulting in a tight fit between the graft and the vessel wall. Side branches narrowed but remained open because of the size of the nylon mesh. No migration of the grafts equipped with a barbed lead stent was noted. Expandable nylon mesh can be used as an endovascular graft material when wrapped around a framework of self-expanding stents. The resulting device can be easily delivered via transcatheter techniques, and once placed in a vessel, the nylon acts as a support for neointimal encasement, which forms a new vascular lumen.

The bird's nest inferior vena cava filter: progress report.

The bird's nest inferior vena cava filter, in clinical trial since 1982, has been placed in 568 patients at risk for pulmonary embolism. Of the 481 patients in whom the filter had been in place for 6 months or more, 440 were followed up clinically. The prevalence of clinically suspected recurrent pulmonary thromboembolism was 2.7% (12 patients) and that of inferior vena cava filter occlusion was 2.9% (13 patients). With the initial filter design, filter migration occurred in five patients. No migrations have occurred in the 147 patients treated with the filter after its modification to improve the anchoring system for greater stability. The bird's nest filter has proved safe and effective in the prevention of pulmonary embolism.

Elastic characteristics of the self-expanding metallic stents.

We measured elastic properties of the self-expanding metallic (Gianturco) stent using Hooke's law to characterize the stent with respect to its caliber, length, and radius by a coefficient of stiffness. Although this coefficient was independent of the radius of the stent, we found that it was directly dependent on caliber. For a stent of a particular caliber and length, the fractional change in radius determined the force exerted by the stent. For small radial displacements of the stent, the force required to compress it was directly proportional to the radial displacements; for large displacements, the force depended on a power series of the fractional radial displacement. A hyperbolic function was empirically introduced to approximate this type of relationship between force and radial displacement. We calculated tension and pressure exerted by the stent and suggest the use of our findings with normal vessels.

Early and late results of intracoronary arterial stenting after coronary angioplasty in dogs.

Intimal dissection with acute closure represents the major complication associated with percutaneous transluminal coronary angioplasty (PTCA). Intracoronary stent devices offer the possibility of treatment for this sequela. We developed a balloon catheter-mounted, flexible coil stent for use in such cases. To determine the utility of this device and its immediate and long-term influence on arterial patency, 39 mongrel dogs had the stent placed after PTCA of the left circumflex or left anterior descending coronary arteries. Thirteen animals were treated before and after the procedure with warfarin. In this group there were three early deaths associated with stent thrombosis. Twenty-six animals were subsequently treated before and after with aspirin and dipyridamole. There were no early thrombotic events associated with stent placement in these animals. Late arteriographic examination revealed patent vessels in all dogs. Diameter stenosis for warfarin-treated dogs was 8 +/- 5% (mean +/- SD) at 2 months (n = 9), 6 +/- 4% at 6 months (n = 5), and 11 +/- 7% at 12 months (n = 3). Diameter stenosis for aspirin/dipyridamole-treated dogs was 9 +/- 3% at 2 months (n = 8), 8 +/- 5% at 6 months (n = 12), and 5% at 12 months (n = 1). Light and scanning electron microscopic analyses of stented arteries demonstrated incorporation of the stent wires into the arterial wall. Early findings included mild thrombosis localized to areas of wire entrenchment followed by rapid regrowth of endothelial and/or pseudoendothelial cells over trenches, exposed wires, and elastica.(ABSTRACT TRUNCATED AT 250 WORDS)

Self-expanding metallic stents: preliminary evaluation in an atherosclerotic model.

The performance of the self-expanding stainless steel (Gianturco) stent in atherosclerotic arteries was examined in a rabbit model. Atherosclerosis was induced by supplementing rabbit chow with 6% peanut oil and 2% cholesterol followed by endothelial disruption of the abdominal aorta with a balloon catheter and continuation on the atherogenic diet for the remainder of the study. Eighteen stents, 1 cm in length and 4 or 5 mm in diameter when fully expanded, were placed in atherosclerotic stenotic lesions in six rabbits. Luminal distention was consistently achieved. At 8 weeks follow-up, no luminal narrowing, stent migration, thrombus formation or branch vessel occlusion had occurred. Atherosclerotic neointimal proliferation occurred around the stent wires following placement, but did not cause significant luminal narrowing.

Percutaneous endovascular graft: experimental evaluation.

An arterial endovascular graft was constructed by wrapping a Dacron cylinder around the Gianturco expandable metallic stent. The device was passed through an 11-F Teflon catheter into the normal abdominal or thoracic aortas of nine dogs. At follow-up of 7-35 weeks, all but one graft remained patent. At necropsy, the grafts were almost completely covered by neo-intimal proliferation. Similar proliferation was observed between the graft and the wall of the vessel.

Self-expanding metallic stents for small vessels: an experimental evaluation.

Thirty-three self-expanding metallic stents were placed in 24 arterial segments of the hind legs and nine arteries of the abdominal viscera in seven dogs. Twelve 5-mm stents, eight 4-mm stents, and 13 3-mm stents were inserted. Follow-up ranged from 4 to 30 weeks. All 4-mm and 5-mm stents were patent at follow-up. Seven (54%) of the 3-mm stents remained patent. Stent wires were completely covered by a proliferation of the intima. No stent migration, occlusion of side branches, or vessel wall perforation was observed. A stent/artery ratio (SAR) was computed using stent and recipient vessel diameters. Good vascular patency was observed when the SAR was less than or equal to 1.2. An SAR greater than 1.2 was associated with immediate spasm, immediate or delayed thrombosis, or excessive intimal proliferation. Selection of correct stent size is a major determinant of patency in small arteries.

Flexible balloon-expanded stent for small vessels. Work in progress.

A new type of flexible, balloon-expanded, stainless steel stent was designed for introduction into small vessels subject to motion. Four stents placed in four dogs were patent at follow-up (4-8 weeks). A fibrocellular proliferation involving the intima and media was responsible for a 20%-25% luminal narrowing observed in all vessels with stents. The stent has longitudinal flexibility, which should permit its insertion into small peripheral, visceral, and coronary arteries.

Stenosis of the vena cava: preliminary assessment of treatment with expandable metallic stents.

To test the ability of Gianturco expandable metallic stents to dilate and maintain patency in stenotic venae cavae, stenosis of the inferior vena cava was created in seven mongrel dogs by the percutaneous injection of absolute ethanol into the paravascular retroperitoneal space. Gianturco stents, placed across the stenotic segment, resulted in successful dilatation with improved hemodynamics in four dogs. The stents failed to dilate an occluded vena cava in one dog; in the remaining dogs, stent placement was complicated by early migration and occlusion. Gianturco stents were placed in two patients, one with superior vena cava syndrome and one with retroperitoneal fibrosis that obstructed the inferior vena cava, and resulted in immediate relief of presenting symptoms. These results should be viewed cautiously, but further investigation into the clinical use of the stents is indicated, especially for patients for whom other treatments are difficult.

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.