Noboru Tanigawa

Reaction of the aortic wall to six metallic stent materials

RATIONALE AND OBJECTIVES We investigated the effects of various metallic stents on the aortic wall. METHODS The wires of Gianturco-type expandable metallic stents were plated with gold, silver, or copper or coated with Teflon or silicone. Stents were inserted into the aortas of 15 adult mongrel dogs. The time course of radiologic, macroscopic, and histologic changes in the aorta at the site of the stent was investigated at 1, 2, and 4 weeks after implantation. RESULTS The gold-plated stent appeared to produce fewer macroscopic and histopathologic changes in the aorta than the other types of stents. The neointima was thinnest with gold (83.9 +/- 40.3 microns), followed by stainless steel (103.6 +/- 57.0 microns), Teflon (115.0 +/- 30.2 microns), silicone (209.6 +/- 25.9 microns), silver (228.6 +/- 33.8 microns), and copper (unmeasurable). With the copper-plated stent, the aorta suffered severe erosion of the vessel wall, marked thrombus formation, and aortic rupture. CONCLUSION Gold is a useful intravascular material because it reacts only minimally with the vessel wall.

Treatment of Takayasu's aortitis with self-expanding metallic stents (Gianturco stents) in two patients

Gianturco self-expanding metallic stents were successfully placed to treat incomplete balloon dilatation of the abdominal aorta in 2 patients with Takayasus aortitis. In 1 case eleven 1-cm long, 1-cm diameter stents were inserted in tandem to bridge a long stenosis. In the other patient, four stents 1.5 cm long, 1.5 cm in diameter were inserted in tandem to bridge what had been a complete occlusion prior to balloon angioplasty. Clinical symptoms, as well as angiographic findings, improved significantly after placement of the stents. The patients underwent repeat aortography at 10 and 8 months, respectively, and were followed clinically for a total of 18 months and 15 months, respectively, without clinical evidence of deterioration. Our results show the usefulness of expandable metallic stents in the treatment of aortic stenosis due to Takayasus aortitis that remains unresponsive to balloon dilatation.

Water Jet Angioplasty — an Experimental Study

The usefulness and safety of water jet angioplasty was studied in vitro, using agar phantom and autopsied aorta, and in vivo in acute and chronic arterial occlusions in mongrel dogs. At an injection rate of 1.0 ml/s, the water jet produced erosion of the agar surface when the distance between the catheter and the agar was 1 mm. With an injection rate of 1.5 ml/s, erosion was produced at a distance of 15 mm from the catheter tip. When the water jet was directed at an arterial wall, intimal ablation and ruptured elastic fibers were found histopathologically. A smaller angle between the vascular wall and the catheter was associated with less vascular damage. In vivo, water jet angioplasty was effective against acute obstructions, but not against chronic obstructions. These results suggest that water jet angioplasty may be effective against arterial obstruction due to acute thrombus.

Endotracheal Expandable Metallic Stent Placement in Dogs

Various types of Gianturco zig-zag wire stent were implanted into the tracheas of 4 dogs to define the suitable characteristics of the endotracheal wire stent in these animals. The stents were constructed of 0.45, 0.40, and 0.33 mm stainless steel wire. The diameter of the fully expanded stents was 3 cm and their lengths were 2, 3, and 4 cm. The 2 cm stent constructed of 0.33 mm wire showed minimum pathologic changes of the trachea of the dog compared to the other stents, and at the same time had a complete covering of ciliated columnar epithelium over the stent surface.

Computed Tomographic Percutaneous Transsplenic Portography

The diagnosis of liver tumors should be utilized for determination of not only the number of lesions, but also their size, segmental location and extent, and the relationship of the mass or masses to the hepatic vasculature. CT during arterial portography (CTAP) is the most sensitive imaging modality for precise diagnosis of hepatocellular carcinoma (1–3, 5). CTAP is thus widely used as a diagnostic imaging technique, particularly for the detection of small hepatocellular carcinomas (4, 6, 8). Conventional splenic portography has been carried out for many years using a wide diameter needle, a large amount of contrast medium and a film-screen system (7). Since the development of arterial portography, fewer splenoportograms have been performed due to the high incidence of bleeding and other complications (7). In this study a 0.6-mm (23 gauge) thin needle was used for splenic puncture and CT was used as a detector instead of a film-screen system. With this technique CT during percutaneous transsplenic portography may be performed on an outpatient basis.

The potential use of I-123 IMP scintigraphy for pelvic bone metastases in hepatocellular carcinoma. A comparison with Ga-67 scintigraphy

Conventional bone scintigraphy is often inconclusive in detecting bone metastases of hepatocellular carcinoma, suggesting the necessity of alternative scintigraphic agents. In this study, the diagnostic value of I-123 IMP scintigraphy was evaluated in 8 patients with 12 pelvic bone metastases from hepatocellular carcinoma, then compared with Ga-67 scintigraphy. Eleven of 12 lesions (91.7%) were detected by I-123 IMP scintigraphy; Ga-67 scintigraphy visualized 8 lesions (66.7%) in the same patient population. I-123 IMP scintigraphy is useful for detecting pelvic bone metastases of hepatocellular carcinoma with less physiologic accumulation in the intestine as compared with Ga-67 scintigraphy.

Intraarterial Occlusion by Radiofrequency

Arterial occlusion using radiofrequency energy was performed. The length of the noninsulated part of the guidewire was 10 mm and the duration of radiofrequency supply was 20 s. Animal experiments were carried out in 17 canine arteries; 4 out of 6 arteries less than 2.3 mm in diameter were completely occluded during the 20 s radiofrequency supply. A clinical application was also successfully performed without any complications. Arterial occlusion with radiofrequency can be applied to vessels less than about 2 mm in diameter.

Percutaneous internal fistulization of a lung abscess after incomplete external drainage

Internal drainage was performed with expandable metallic stents in a 79-year-old male with lung abscess secondary to bronchogenic carcinoma. Initial external drainage was prolonged, and internalization of drainage allowed removal of the external drainage catheter. Connection of abscess cavity to obstructed bronchus was created after passing a steerable guidewire percutaneously through the abscess into the bronchus. This new type of internal drainage technique may be applicable to patients with prolonged standard percutaneous external drainage of lung abscesses.

Clinical Experience of 123I-IMP Scintigraphy in Detecting Vertebral Bone Metastases of Hepatocellular Carcinoma A Comparison with Bone Scintigraphy with 99mTc-MDP

Although bone scintigraphy with 99mTc-MDP is a sensitive diagnostic method to detect bone metastasis, it is not specific for malignancy. A radioactive substance which accumulates specifically into metastatic lesions should be of value. 123I-IMP and bone scintigraphy with 99mTc-MDP were consecutively performed in patients with vertebral bone metastases from hepatocellular carcinoma and lumbar spondylosis deformans in a 7-day interval or shorter. The intensity of uptake was compared. Eighteen of the 20 metastatic lesions (90%) were classified as increased uptake areas in 123I-IMP scintigraphy. MDP-scintigraphy disclosed 16 metastatic lesions (80%), 9 as “hot” lesions (56%) and 7 as “cold” lesions (44%). 123I-IMP scintigraphy was negative in all 12 lesions of lumbar spondylosis deformans. Compared to MDP-scintigraphy, 123I-IMP scintigraphy was more sensitive in detecting vertebral bone metastases of hepatocellular carcinoma with smaller rates of false-positive and false-negative findings.