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Anterior thalamic nucleus stimulation: issues in study design
Published in Hans O Lüders, Deep Brain Stimulation and Epilepsy, 2020
Potential risks of an MRI in this setting are discussed in the consent forms. Theoretical problems with post-operative MRI include: heating of the implanted electrode if an inadvertent short circuit allows circulating current to be produced by the magnetic fieldrapid on-off cycling of the device due to toggling of the magnetic switch in the KinetraBreakage of the devicemovement of the wires due to interaction with the magnetic fieldother unknown risks.
Effects of Neuropeptides on Intestinal Ion Transport
Published in Edwin E. Daniel, Neuropeptide Function in the Gastrointestinal Tract, 2019
In vitro studies have been used to explore in greater detail the underlying mechanisms. Rabbit, guinea pig, rat, and pig intestines have been studied. In all four species, NPY/PYY caused decreases in short circuit current. In rabbit ileum, NPY produced dose-dependent decreases in Isc, with EC50s between 3 to 5 × 10−8M. PYY appeared to be more potent, with an EC50 of 2 × 10−9M. Hubel and Renquist92 noted that TTX did not inhibit effects of NPY, and Friel et al.90 showed that yohimbine had no significant inhibitory effects either. The logic underlying the use of the latter antagonist was the observation that α2-adrenoceptor effects on rabbit intestines were similar to those seen with NPY. Densensitization of responses were noted with NPY.92 However, interestingly, a desensitized tissue still responded to transmural field stimulation. These studies suggested that the effects of NPY were largely direct in keeping with the observed topographical location of NPY-immunoreactive nerves close to the epithelium. On the porcine jejunum,91 effects of NPY were inhibited by both TTX and the opiate antagonist naloxone, suggesting the possible involvement of opioid interneurons.
Quality assurance
Published in Peter R Hoskins, Kevin Martin, Abigail Thrush, Diagnostic Ultrasound, 2019
Nick Dudley, Tony Evans, Peter R Hoskins
The FirstCall (Unisyn, Golden, Colorado) electronic probe tester was developed to test the relevant acoustic and electrical parameters of ultrasound probes. Testing is performed by attaching the probe connector to a dedicated adapter and mounting the probe at the surface of a water bath parallel to a steel reflecting plate. Three plates are available: a flat plate for linear and phased arrays, a plate with a large radius of curvature matched to typical convex arrays for abdominal use and a more tightly curved plate matched to typical endocavity probes. The entire array is pulsed, one element at a time, and a sensitivity plot produced. The system then measures the capacitance of each element circuit and displays a capacitance plot; there are a number of probes where the FirstCall cannot measure capacitance. The capacitance results allow the user to determine whether low sensitivity is due to a short circuit, open circuit or damaged element. Additionally the system provides plots of pulse width, centre frequency and fractional bandwidth for each element and pulse shapes and frequency spectra for three user selected elements. A similar device, with some added features, is available (ProbeHunter: BBS Medical AB, Stockholm, Sweden).
Feasibility of distal transradial access for coronary angiography and percutaneous coronary intervention: an observational and prospective study in a Latin-American Centre
Published in Acta Cardiologica, 2023
Héctor Hugo Escutia-Cuevas, Marco Alcantara Melendez, Arnoldo Santos Jiménez-Valverde, Gregorio Zaragoza-Rodriguez, Antonio Vargas-Cruz, Juan Francisco Garcia-Garcia, Bayardo Antonio Ordonez-Salazar, Antonio Flores-Morgado, Guillermo Orozco Guerra, Diego Alvaro Renteria-Valencia
For the convenience of the operator, initial access was right distal transradial, in the case of not being able to achieve this access the first alternative was the left distal transradial access (ldTRA); the causes associated with the initial use of ldTRA were:Right radial artery occlusion.Underdeveloped right radial artery.Prior tortuosity of the right radial artery was observed. Sclerosis or calcifications.Lusoria artery.Previous failed attempt on the right radial artery.Presence of arteriovenous short circuit.Previous use or foreseen future use of right radial artery for bypass graft.Patients with surgical revascularization who require left internal mammary artery graft angiography.Patient preference.
Electrode migration after cochlear implantation
Published in Cochlear Implants International, 2021
Christian von Mitzlaff, Adrian Dalbert, Sebastian Winklhofer, Dorothe Veraguth, Alexander Huber, Christof Röösli
Electrode impedance measurements were performed after 4, 5, and 7 weeks postoperatively and later every 6–12 month depending on the patient’s follow up plan. Analysis was performed for every ear implanted using the software ‘Custom Sound EP’ (version 5.1.1.213). Changes in electrode impedance were further classified as short circuits (SC) and open circuits (OC). SC exist when two lead wires of the electrode array are in direct contact with one another and are thus always visible on two or more electrodes of the same electrode array. Definitions differ across manufacturers, but SC typically show a decrease in impedance i.e. 1 kOhm or less. OC are defined as increased resistance with impedance values >20–30 kOhm. Reasons for OC are air bubbles in direct proximity of the electrode as well as breaks of the electrode array (Goehring et al., 2013). In patients in whom basal electrodes (1, 2 or 3) were switched off, surgery report was consulted to check whether complete insertion was achieved intraoperatively. If a basal electrode was switched off and full insertion at the time of surgery was documented, electrode migration was suspected. These patients were subsequently contacted and, after consenting, a CT scan was performed.
Alternative Access for Mechanical Circulatory Support
Published in Structural Heart, 2020
Mir B. Basir, Marvin H. Eng, Pedro Villablanca, Mark B. Anderson, Mohammad Zaidan, Dee Dee Wang, Khaldoon Alaswad, William W. O’Neill, Mohammad Alqarqaz
Troubleshooting: Exercise caution with cases of difficult crossing. Firstly, avoid wire buckling as it leads to an uncontrolled, electrified guidewire to lacerate the aorta. Also, multiple attempts may inadvertently cause an aortic breach to go undetected. Otherwise, recheck the connections to the electrosurgical unit, confirm electrosurgical monopolar cutting is set to 50 W and a clean contact point between the coronary wire and electrosurgical pencil. Avoid crossing wire looping to prevent a short circuit. Several failed traversal attempts chars the wire tip preventing energy transmission. An alternate crossing point can be selected based on calcium distribution but angiography should confirm that no aortic puncture resulted from the failed attempts. Resistance to catheter crossing should prompt angioplasty with a 2.5–3.0 mm non-compliant coronary balloon. Ensure match dilation of both the aortic and caval sides of the tract to prevent venous obstruction and facilitate venous decompression.