Stent obstruction

Fig. 5.12a, b. A 71-year-old male patient with bronchogenic carcinoma invading the mediastinum and brain metastasis. Superior vena cava obstruction syndrome was treated by placement of a Wallstent endoprosthesis in the superior vena cava. At 3 weeks after endoluminal treatment, obstruction symptoms recurred, a Phlebography obtained by a femoral approach and catheterization of the stent lumen showed stent obstruction, and extensive filling of mediastinal veins, b After balloon dilatation at the junction of the stent with the internal jugular vein, a residual stenosis (arrow), due to insufficient stent covering of mediastinal tumor extent was evident... 

Cardiac catheterization and coronary angiography are used in patients with suspected CAD to document the presence and severity of disease as well as for prognostic purposes. Interventional catheterization is used for thrombolytic therapy in patients with acute MI and for managing patients with significant CAD to relieve obstruction through percutaneous transluminal coronary angioplasty, atherectomy, laser treatment, or stent placement. 

One of the most commonly used medical devices is the stent, (Fig. 21.1), small metallic structures that are expanded in blood vessels, functioning to maintain the patency (freedom from obstruction) of the vessel in which it is placed. Although the first use of stents was in vasculature (blood vessel systems), more recent applications include, for example, implantation between two vertebrae to increase the rigidity of the spine. A typical vascular stent is placed in its anatomical location and then either plastically deformed/expanded (stainless steel) or allowed to expand to a predetermined size, as a consequence of shape memory (nitinol). 

Sirolimus has also been used in the production of sirolimus-eluting stents. These stents are used to treat obstructive coronary arteries. The rationale for the use of sirolimus in these stents is due to its antiproliferative activity. It has also received attention for cancer treatment due to its antiproliferative effects. In animal studies, sirolimus has shown some potential in the treatment of cancer where in combination with doxorubicin, a remission for Akt-positive lymphomas has been observed. 

By IVUS, the neointimal hyperplasia volume amounted to 32,3 16.4 mm3 with the stent volume of 143.7 43.7 mm3, resulting in a mean neointimal volume obstruction of 23.5 12.5%. None of the patients had >50% volume obstruction by MJS (Fig. 6). There was no evidence of stent malapposrtion or echolucent images ( black hole ). 

Removal of balloon-occlusive EPDs is preceded by aspiration of 50-60 ml of blood using a dedicated catheter. Filter-based EPDs are removed using a dedicated retrieval catheter. Difficulties in advancing the retrieval catheter through the stent are at time eliminated by having the patient rotate his/her neck. Rarely, the filter can become obstructed by large amounts of embolic material and blood flow in the ICA is interrupted. Facile technique and optimal antiplatelet therapy prevent this complication in most cases. 

A 39-year-old patient, Mrs DS, known to urology (as had left ureteric obstruction which was stented), presents with back pain and lower left-sided abdominal pain with rigors and nausea. She has lost 2 stone (12.7 kg) in weight and cannot work. 

Xu, K., He, F.-X., Zhang, H.-G., Zhang, X.-T., Han, M.-J., Wang, C.-R., Kaneko, M., T ahashi, M., Okawada, T. Budd-Chiari syndrome caused by obstruction of the hepatic inferior vena cava immediate and 2-year treatment results of transluminal angioplasty and metalHc stent placement. Cardiovasc. Intervent. Radiol. 1996 19 32—36... 

Ursodeoxycholic acid 250 mg tds plus ofloxacin 200 mg bd has been compared with ursodeoxycholic acid alone in the prevention of occlusion of biliary stents in a randomized trial in 52 patients with inoperable obstructive jaundice (6). Combination treatment was not superior to ursodeoxycholic acid alone. There was no significant difference in the frequency of adverse events between the two groups. 

Treatment of sulfadiazine nephrotoxicity consists in stopping sulfadiazine or decreasing its dosage. The acute kidney injury, however, may resolve despite continuation of the treatment [41]. Hydration and especially alkalinization are the basis for the treatment. Urinary tract obstruction may require placement of ureteral stents [13] or nephrostomy [33]. This complication is essentially reversible and dialysis is rarely needed [27]. 

Lee BH, Choe DH, Lee JH, Kim KH and Chin SY (1997) Metallic stents in malignant biliary obstruction prospective long-term clinical results. Am J Roentgenol 168 741-745. 

Although coronary stents have been a breakthrough in the treatment of obstructive coronary disease, there have been adverse effects in patients, such as restenosis. Much research has gone into addressing this situation. Researchers have looked at coating stents for localized drug delivery and results have shown that delivery of a low dose of paclitaxel (PTx shown in Figure 12) has proved to be cytostatic but not cytotoxic [33]. 

Shah R, Sabanathan S, Lowe RA et al (1996) Stenting in malignant obstruction of superior vena cava. J Thorac Cardiovasc Surg 112 335-340... 

Oderich GS, Treiman GS, Schneider P et al (2000) Stent placement for treatment of central and peripheral venous obstruction A long-term multi-institutional experience. J Vase Surg 32 760-769... 

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