nitinol and Calcinosis

Deposition of dystrophic calcifications on the posterior surface of silicone intraocular lenses (IOLs) has been reported in patients with asteroid hyalosis. Accumulation of silicone oil droplets on the posterior surface of silicone IOLs in silicone-filled eyes has also been reported. Recently, a novel technique to manually remove dystrophic calcifications using a nickel titanium loop (Finesse Flex Loop; Alcon, Fort Worth, TX) was described, obviating the need for IOL exchange. Here, the authors report their outcomes with this technique in five eyes with IOL dystrophic calcifications as well as one eye with IOL silicone oil droplet accumulation. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:422-426.].

Topics: Aged; Aged, 80 and over; Alloys; Calcinosis; Equipment Design; Eye Diseases; Female; Follow-Up Studies; Humans; Lenses, Intraocular; Male; Middle Aged; Ophthalmologic Surgical Procedures; Postoperative Complications; Prosthesis Failure; Silicone Oils

Topics: Aged, 80 and over; Alloys; Calcinosis; Humans; Lenses, Intraocular; Male; Silicones; Treatment Outcome; Vision Disorders; Vitrectomy

An approach for extracting the radial force load on an implanted stent from medical images is proposed. To exemplify the approach, a system is presented which computes a radial force estimation from computer tomography images acquired from patients who underwent transcatheter aortic valve implantation (TAVI). The deformed shape of the implanted valve prosthesis' Nitinol frame is extracted from the images. A set of displacement vectors is computed that parameterizes the observed deformation. An iterative relaxation algorithm is employed to adapt the information extracted from the images to a finite-element model of the stent, and the radial components of the interaction forces between the stent and the tissue are extracted. For the evaluation of the method, tests were run using the clinical data from 21 patients. Stent modeling and extraction of the radial forces were successful in 18 cases. Synthetic test cases were generated, in addition, for assessing the sensitivity to the measurement errors. In a sensitivity analysis, the geometric error of the stent reconstruction was below 0.3 mm, which is below the image resolution. The distribution of the radial forces was qualitatively and quantitatively reasonable. An uncertainty remains in the quantitative evaluation of the radial forces due to the uncertainty in defining a radial direction on the deformed stent. With our approach, the mechanical situation of TAVI stents after the implantation can be studied in vivo, which may help to understand the mechanisms that lead to the complications and improve stent design.

Topics: Alloys; Aortic Valve; Biomechanical Phenomena; Calcinosis; Finite Element Analysis; Heart Valve Prosthesis; Heart Valve Prosthesis Implantation; Humans; Image Processing, Computer-Assisted; Prosthesis Design; Stents

Topics: Alloys; Angioplasty, Balloon; Arterial Occlusive Diseases; Calcinosis; Equipment Design; Femoral Artery; Humans; Male; Middle Aged; Prosthesis Design; Radiography, Interventional; Stents; Treatment Outcome

To compare quantitative and qualitative parameters obtained from digital subtraction angiography (DSA) with multislice computed tomographic angiography (MSCTA) in the follow-up of superficial femoral artery (SFA) stents.. Thirteen patients who had SMART stents implanted in the SFA were examined systematically with DSA and MSCTA (16-row scanner) at 6 months. Quantitative analysis and morphological assessment were performed on DSA images by an independent core laboratory, while the MSCTA images were analyzed by 2 radiologists in consensus. DSA measurements included stent length, minimal lumen diameter and reference diameter at mid stent and 5 mm either side of the stent, and percentage of stenosis. For MSCTA images, lumen area and the minimum, maximum, and mean diameters were also recorded. The images were analyzed qualitatively for diameter stenosis (<50%, 50% to 70%, 71% to 99%, and occlusion), bends, fractures, and calcifications.. There were no statistical differences between lengths of stented segments, diameter measurements, or percentages of stenosis from DSA and MSCTA images. The Bland-Altman method showed good agreement between the 2 methods of measurement. MSCTA detected in-stent proliferation with a diameter stenosis <50% in all 13 cases diagnosed on DSA (there was no stenosis >50%). There were no bends or stent fractures on either set of images. The agreement between DSA and MSCTA for the presence and grading of calcifications was moderate (kappa=0.5).. MSCTA provided quantitative and qualitative data comparable with DSA in the analysis of SFA nitinol stents.

Topics: Aged; Aged, 80 and over; Alloys; Angiography, Digital Subtraction; Atherosclerosis; Blood Vessel Prosthesis Implantation; Calcinosis; Female; Femoral Artery; Follow-Up Studies; Humans; Male; Middle Aged; Radiographic Image Interpretation, Computer-Assisted; Research Design; Severity of Illness Index; Stents; Tomography, X-Ray Computed; Treatment Outcome

Reducing the negative side effects associated with extracorporeal circulation is the major advantage of off-pump revascularization. However, side clamping of a calcified aorta for proximal anastomoses can cause emboli, resulting in neurologic damage. This problem has been addressed by introducing a mechanical anastomosis device (Symmetry, St Jude Medical) that allows vein-to-aorta anastomosis without manipulating the aorta. This report describes our experience with this device.. Between June 2001 and April 2002, 77 connectors (1.3 per patient) were deployed in 61 patients (51 men and 10 women; mean age, 68 +/- 8.6 years) undergoing off-pump coronary artery bypass grafting or beating-heart revascularization. Intraoperative quality assessment included transit-time flow measurement (Medistim) and indocyanine green-based angiography (Spy, Novadaq).. The surgeons were meticulously trained in loading of the device. No postoperative neurologic deficits were detected. Fifty-three patients had an uneventful course. However, 8 (13.1%) patients with 12 implanted connectors were symptomatic within 8 months (1 day to 8 months). Angiography revealed significant (95%) stenosis or even occlusion of the proximal vein-to-aorta anastomosis at the level of all connectors. Four patients underwent reoperation (2 dilated-stented and 2 treated with drugs).. On the basis of these observations, the routine use of the connector was halted at our institution. At the moment, the use of this therapy is reserved for patients with severely calcified aortas with no technical alternative. Further investigations appear necessary to evaluate the clinical patterns of this otherwise promising technology.

Topics: Aged; Alloys; Anastomosis, Surgical; Aorta; Aortic Diseases; Calcinosis; Coronary Angiography; Coronary Artery Bypass; Equipment Failure; Female; Graft Occlusion, Vascular; Humans; Male; Postoperative Complications; Veins