Flexible tantalum stents for the treatment of renovascular hypertension: a 10-year experience

Abstract

The aim of this study was to determine long-term success of flexible tantalum stents for the treatment of ostial and truncal renal artery stenosis. Since 1989, flexible tantalum stents (type Strecker) were implanted in 34 patients (36 arteries, 25 ostial lesions, 11 truncal lesions) with uncontrollable renovascular hypertension, 9 of them in association with renal insufficiency. Stents were placed unilaterally in 32 patients, and bilaterally in 2 patients for the treatment of renal artery stenosis. Thirty-five of 36 lesions were atherosclerotic, including 5 recurrencies after previous percutaneous transluminal renal angioplasty (PTRA). One patient had Takayasu arteritis. Stents were implanted after unsuccessful PTRA of 11 truncal and 23 ostial lesions, and as a primary procedure in 2 ostial lesions. Follow-up examinations included blood pressure measurement, determination of serum creatinine level, color duplex sonography, or angiography. The technical success rate was 92%. Technical failure included incorrect stent placement (1 of 36 lesions, 2.8 % ), and stent dislocation (2 of 36 lesions, 5.6 %), and two stents were retrieved percutaneously. In one case of Takayasu arteritis, residual stenosis of 40% was observed. After technically successful stent placement, 77% of patients became normotensive with or without medication. In the remaining patients there was partial improvement with blood pressure between 140 and 180 mmHg. Renal function improved in 76% of patients (completely in 3 of 8, 38%; and partially in 3 of 8, 38%). Primary patency rate including all stented lesions and initial technical failures was 82.4% +/- 6.8 (1 year) and 82.4% +/- 9.2 (3 years). After technically successful stent placement, patency rates were 89.9 +/- 5.6% (1 year), and 89.9 +/- 7.6% (3 years). For ostial lesions, primary patency rate was 87.9 +/- 6.7% (1 year) and 87.9 +/- 9.2% (3 years). Placement of flexible tantalum stents in renal arteries is technically demanding, especially in ostial lesions. Once placed successfully stent patency rate is excellent.

A comprehensive review of biological and materials properties of Tantalum and its alloys

“…39 Upon moving to clinical studies, the use of the Strecker Ta stents was established in various arteries including coronary, 35 femoro-popliteal, 36 iliac, 37 and renal arteries. 38 Hausegger et al 37 The goal of this study was to assess whether the differences in stent material (316 L SS vs. Ta) and stent design influenced the clinical outcome. The results showed that both stents were equally effective in restoring the blood vessel patency and blood flow.…”

A clinical survey of vascular stents

“…12 mm Hg, or poor angiographic flow), stenoses near the ostium or heavily calcified lesions, dissections after PTA, or aortic dissection with involvement of the RA. Recent RA stent trials have shown satisfactory patencies: 65 and 79% at 6 months [30,31], 84% at 7 months [32], and 83.1% at 8 months [33], together with 1-year results of 75%, 85%, and 89.9%, respectively, in three different trials [34][35][36]. Long-term results are also good, with 79% patency at 16 months [37], 77% at 29 months [38], and even 79% being reported at 60 months follow-up [39] (see Table 2).…”

Tantalum

“…Flexible tantalum stents are used in a variety of surgical applications including intravascular procedures (Strecker et al 2000(Strecker et al , 2001, treatment of bronchial disease (Hautmann et al 2000) and biliary obstruction (Lee et al 1997). Flexible tantalum stents are used in a variety of surgical applications including intravascular procedures (Strecker et al 2000(Strecker et al , 2001, treatment of bronchial disease (Hautmann et al 2000) and biliary obstruction (Lee et al 1997).…”