8 research outputs found
Pacemaker twiddler's syndrome
No full textAbstract
A 76-yr-old man with unipolar ventricular pacemaker, previously
implanted in the right ventricular apex, presented with
syncopal attack and twitching of the right pectoralis muscle.
He finally was diagnosed as having Twiddler's syndrome. The
patient had a pulse rate of 36/min and cannon waves in the
neck veins. Chest radiography showed a dislodged pacing lead
completely wrapped around the pulse generator. After uncoiling
the lead it was positioned in the right ventricular apex and
the pulse generator implanted and sewed tightly in a smaller
pocket. After six months follow-up there was no further twiddling
or pacemaker dysfunction
A novel approach for multiple mobile objects path planning: Parametrization method and conflict resolution strategy
No full text
A novel algorithm based on parameterization method for calculation of curvature of the free surface flows
No full textAbstractIn this paper, a new approach based on parameterization method is presented for calculation of curvature on the free surface flows. In some phenomena such as droplet and bubble, surface tension is prominent. Therefore in these cases, accurate estimation of the curvature is vital. Volume of fluid (VOF) is a surface capturing method for free surface modeling. In this method, free surface curvature is calculated based on gradient of scalar transport parameter which is regarded as original method in this paper. However, calculation of curvature for a circle and other known geometries based on this method is not accurate. For instance, in practice curvature of a circle in interface cells is constant, while this method predicts different curvatures for it. In this research a novel algorithm based on parameterization method for improvement of the curvature calculation is presented. To show the application of parameterization method, two methods are employed. In the first approach denoted by, three line method, a curve is fitted to the free surface so that the distance between curve and linear interface approximation is minimized. In the second approach namely four point method, a curve is fitted to intersect points with grid lines for central and two neighboring cells. These approaches are treated as calculus of variation problems. Then, using the parameterization method, these cases are converted into the sequences of time-varying nonlinear programming problems. With some treatments a conventional equivalent model is obtained. It is finally proved that the solution of these sequences in the models tends to the solution of the calculus of variation problems. For verification of the presented methods, curvature of some geometrical shapes such as circle, elliptic and sinusoidal profile is calculated and compared with original method used in VOF process and analytical solutions. Finally, as a more practical problem, spurious currents are studied. The results showed that more accurate curve prediction is obtained by these approaches than the original method in VOF approach
A Fast and Robust Technique for Accurate Measurement of the Organic-Rich Shales Characteristics under Steady-State Conditions
No full textComparison of the cost-effectiveness of transesophgeal and transthoracic echocardiographies to detect cardioembolic causes of stroke in non-selected patients
No full textBackground: Both Transthoracic Echocardiography (TTE) and Transesophgeal Echocardiography (TEE) are effective investigation tools to detect cardioaortic sources of embolism in ischemic stroke. Nevertheless, there are still uncertainties about the cost-effectiveness of these methods in non-selected patients with acute stroke. Objectives: This study aimed to investigate the cost-effectiveness of TTE and TEE using a decision analytic model in non-selected patients with acute ischemic stroke with or without clinical and radiological signs of embolic pattern. Patients and Methods: This cross-sectional cost-effectiveness study was performed in Nemazee hospital affiliated to Shiraz University of Medical Sciences from January 2014 to April 2014. TTE and TEE were performed for all 65 consecutive patients with ischemic stroke (51.3 male, mean age of 69.7 ± 17.9 years). The required data were direct costs related to performance of TTE and TEE, which were obtained from the patients� bills in their charts. A decision analytic model was implemented to assess the cost-effectiveness of these two methods, which demonstrated an Incremental Cost-Ef-fectiveness Ratio (ICER). Effectiveness was determined based on the number of disorders diagnosed using each of the two echoes confirmed by two cardiologists. All analyses were done using Tree Age Pro 2011. Results: The results showed that TEE was more expensive than TTE in non-selected patients. Performing TEE increased the cost by 1494 USD and the effectiveness by 7. As per ICER equation, for each increment unit in the effectiveness, performing TEE would increase the cost by 213.4 USD compared to TTE. TEE was cost-effective in comparison to TTE regardless of age factor considering the cutoff of Gross Domestic Product (GDP) by three for ICER. Moreover, TTE was cost-effective in 41-60-and 61-80-year-old age groups, while TEE was cost-effective in the 41-60-year-old age group. However, none of the techniques was cost-effective in patients above 81 years old. Conclusions: The results of this study can help reduce the unnecessary use of echocardiography by considering the age group and their corresponding risk factors for developing ischemic stroke. © 2018, Iranian Cardiovascular Research Journal. All rights reserved
