Transcatheter aortic valve implantation of the direct flow medical aortic valve with minimal or no contrast.

The 18F Direct Flow Medical (DFM) THV has conformable sealing rings, which minimizes aortic regurgitation and permits full hemodynamic assessment of valve performance prior to permanent implantation. During the DISCOVER trial, three patients who were at risk for receiving contrast media, two due to severe CKD and one due to a recent hyperthyroid reaction to contrast, underwent DFM implantation under fluoroscopic and transesophageal guidance without aortography during either positioning or to confirm the final position. Valve positioning was based on the optimal angiographic projection as calculated by the pre-procedural multislice CT scan. Precise optimization of valve position was performed to minimize transvalve gradient and aortic regurgitation. Prior to final implantation, transvalve hemodynamics were assessed invasively and by TEE. The post-procedure mean gradients were 7, 10, 11mm Hg. The final AVA by echo was 1.70, 1.40 and 1.68cm(2). Total aortic regurgitation post-procedure was none or trace in all three patients. Total positioning and assessment of valve performance time was 4, 6, and 12minutes. Contrast was only used to confirm successful percutaneous closure of the femoral access site. The total contrast dose was 5, 8, 12cc. Baseline eGFR and creatinine was 28, 22, 74mL/min/1.73m(2) and 2.35, 2.98, and 1.03mg/dL, respectively. Renal function was unchanged post-procedure: eGFR=25, 35, and 96mL/min/1.73m(2) and creatinine=2.58, 1.99, and 1.03mg/dL, respectively. In conclusion, the DFM THV provides the ability to perform TAVI with minimal or no contrast. The precise and predictable implantation technique can be performed with fluoro and echo guidance.

Midterm stability and hemodynamic performance of a transfemorally implantable nonmetallic, retrievable, and repositionable aortic valve in patients with severe aortic stenosis. Up to 2-year follow-up of the direct-flow medical valve: a pilot study.

BACKGROUND: Misplacement during percutaneous aortic valve implantation can be associated with severe complications. The direct flow medical (DFM) valve is repositionable and retrievable; however, the nonmetallic inflatable and conformable design of the valve results in less radial force, which may have an impact on stability and valve function over time. We, therefore, analyzed the midterm stability of the position, shape, and hemodynamic performance of the DFM percutaneous aortic valve. METHODS AND RESULTS: Sixteen symptomatic high-risk for surgery patients with aortic stenosis and a logistic EuroSCORE >20 underwent implantation and were the subject of this analysis. Clinical, echocardiographic, and dual-source multislice computed tomography data were obtained during 2-year follow-up. The 1- and 2-year survival rates were 81% and 69%, respectively. The dual-source multislice computed tomography follow-up indicated no changes in position, diameter, and orifice area of the DFM valve over time. Echocardiography revealed a significant decrease of the mean gradient from baseline (50.1±11.3 mm Hg) to 30 days (19.6±5.7 mm Hg, P<0.001), which remained stable over 2 years. The aortic valve area increased from 0.57±0.15 cm(2) at baseline to 1.47±0.35 cm(2) at 30 days (P<0.001) and did not significantly change during 2-year follow-up. Of the patients, 73% had no aortic regurgitation (AR) and 27% had minimal AR. CONCLUSIONS: In this preliminary series, the 2-year follow-up data of patients, in whom the nonmetallic, repositionable, and retrievable DFM valve was successfully implanted, show stability of the position, shape, and hemodynamic performance, with no AR in most patients.

Melanin and Glycera jaws: emerging dark side of a robust biocomposite structure.

Defining the design principles guiding the fabrication of superior biocomposite structures from an assemblage of ordinary molecules is a key goal of biomimetics. Considering their low degree of mineralization, Glycera jaws have been shown to be extraordinarily resistant to abrasion based on the metric hardness3/Young's modulus2. The jaws also exhibit an impressive chemical inertness withstanding boiling concentrated hydrochloric acid as well as boiling concentrated sodium hydroxide. A major organic component largely responsible for the chemical inertness of the jaws has been characterized using a spectrophotometric assay for melanin content, 13C solid state nuclear magnetic resonance, IR spectroscopy, and laser desorption ionization-time of flight mass spectrometry and is identified here as a melanin-like network. Although melanin is widely distributed as a pigment in tissues and other structural biomaterials, to our knowledge, Glycera jaws represent the first known integument to exploit melanin as a cohesive load- and shape-bearing material.