Corrosion testing of stents: a novel fixture to hold entire device in deployed form and finish

Stainless steel and nickel-titanium alloy stents for cardiac, biliary, and prostatic clinical applications may be susceptible to loss of mechanical integrity/failure due to their small size and unique geometry. Because their corrosion behavior is a critical aspect of their biocompatibility, it is necessary to test such devices for corrosion behavior using a final deployed form and finish condition. Welding wire leads or holding with metallic clips can result in surface variability or damage to the stents. A novel fixture to hold stents for corrosion testing was designed and evaluated in this study. This fixture design minimally influenced the properties of stents, and also facilitated easy removal post-testing for other types of characterization.     

Antiphospholipid syndrome presenting as dilated cardiomyopathy in an 11-year-old boy

We report on an 11-year-old Omani boy who presented with acute heart failure due to dilated cardiomyopathy. Examination revealed the presence of left ventricular thrombi on echocardiography and a marked elevation of anticardiolipin antibodies. Subsequently the boy exhibited features of antiphospholipid syndrome including multiple thrombotic episodes involving the brain, and renal and iliac veins. We could not document any underlying cause of the antiphospholipid syndrome. His cardiac status subsequently deteriorated and he expired from multiorgan failure. Resistant heart failure from dilated cardiomyopathy secondary to primary antiphospholipid syndrome is uncommon and has not been reported in children.     

One-Year Follow-up of Duodenal Ulcers after 1-Wk Triple Therapy for Helicobacter pylori

Objective : to study the ulcer recurrence rate of Helicobacter pylori-positive duodenal ulcers at 1 yr after eradication of the bacteria by triple therapy. Method : Patients with H. pylori-positive duodenal ulcers were randomized to receive either triple therapy for 1 wk plus omeprazole for 4 wk (THple+OMP) (n = 78), or omeprazole alone (OMP) for 4 wk (N = 77). Patients were followed up every 3 months for symptom enquiry. At 1 yr, all asymptomatic patients were invited to attend for gastroscopy. Results : At 8 wk, 16 patients in the OMP group and four in the Triple+OMP group had an ulcer. During the 1-yr period, 12 patients in the OMP group and no patient in the Triple+OMP group developed symptomatic ulcers. At follow-up endoscopy at 1 yr, another 10 ulcers were detected in the OMP group and two in the Triple+OMP group. Fifteen patients in the OMP group and 13 in the Triple+OMP group were lost to follow-up. In total, ulcers were de-tected in 39 of 61 (64%) assessahle patients in the OMP group, and in six of 65 (97o) assessahle patients in the Triple+OMP group after I yr (χ² test: p < 0.001). Of the patients whose H, pytori were successfully eradicated hy Triple+OMP at 8 wk, 90% remained H. pylori negative at 1 yr. Conclusion : Triple therapy for 1 wk eradicates H, pylori infection and significantly reduces duodenal ulcer relapses.     

Evaluation of in-stent stenosis by magnetic resonance phase-velocity mapping in nickel-titanium stents

PURPOSE: To evaluate different grades of in-stent stenosis in a nickel-titanium stent with MRI. MATERIALS AND METHODS: Magnetic resonance phase velocity mapping (MR-PVM) was used to measure flow velocity through a 9-mm NiTi stent with three different degrees of stenosis in a phantom study. The tested stenotic geometries were 1) axisymmetric 75%, 2) axisymmetric 90%, and 3) asymmetric 50%. The MR-PVM data were subsequently compared with the velocities from computational fluid dynamic (CFD) simulations of identical conditions. RESULTS: Good quantitative agreement in velocity distribution for the 50% and 75% stenoses was observed. The agreement was poor for the 90% stenosis, most likely due to turbulence and the high-velocity gradients found in the small luminal area relative to the pixel resolution in our imaging settings. CONCLUSION: The accuracy of the MRI velocities inside the stented area renders MRI a modality that may be used to assess moderate to severe in-stent restenosis (ISR) in medium-sized vascular stents in peripheral vessels, such as the iliac, carotid, and femoral arteries. Advances in MR instrumentation may provide sufficient resolution to obtain adequate velocity information from smaller vessels, such as the coronary arteries, and allow MRI to substitute for invasive and expensive catheterization procedures currently in clinical use.