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排序方式: 共有988条查询结果,搜索用时 15 毫秒
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Q. Timour JF Aupetit J. Loufoua-Moundanga I. Kiouch S. Omar G. Chevrel and G. Faucon 《Fundamental & clinical pharmacology》1992,6(4-5):159-167
Class Ic antiarrhythmic drugs, which are known to slow down conduction in the ventricular muscle, are likely to impair synchrony in activity of the ventricular fibres. Asynchronous activation was first investigated between an ischaemic and a normal area by the simultaneous recording in anaesthetized, open-chest pigs of two left ventricular monophasic action potentials (MAPs) under ventricular pacing at a high rate of 180 beats.min-1. Asynchronous activation was then investigated in the intact myocardium according to the distance separating the recording from the pacing electrode. Furthermore, mechanical effects of left ventricular systole were observed by recording dP/dt(max) and mean arterial blood pressure during the pacing periods. Ischaemia was produced by transient complete occlusion of the left anterior descending coronary artery near its origin; as a result, activation time reached 85 ms in the ischaemic area under flecainide administered iv in a 2.5 mg.kg-1 dose instead of approximately 60 ms in the normal area for fibres equi-distant from the pacing electrode. Similar delays in activation were observed in the intact myocardium, depending on whether the explored region was close to or far from the pacing electrode. In the latter case, the difference in activation time may become markedly greater if the distance or the dose of flecainide are increased. This difference, which possibly exceeds one-third of the MAP duration (practically unchanged by flecainide), may account for the occurrence of fibrillation or the sudden loss of systole mechanical efficacy. 相似文献
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J M Mountz W L Rogers M W Wilson N H Clinthorne M D Gross N N Speed J A Schwartz 《Clinical nuclear medicine》1991,16(8):562-567
We have performed initial clinical studies using the high resolution single photon ring tomograph (SPRINT) and Tc-99m HMPAO. To determine what additional anatomic detail can be depicted using this high resolution, dedicated head, multidetector SPECT device compared to conventional SPECT, six patients with stroke and one normal volunteer were imaged after the injection of 20 mCi Tc-99m HMPAO on a conventional rotating Anger gamma camera (GE-400AC), followed immediately by imaging on SPRINT. Imaging acquisition on the GE-400AC gamma camera was performed using 360 degrees rotation, 64 stops, at 30 sec/stop, yielding an average of 985,714 counts for a 10.0 mm thick slice. GE-400AC images were of good quality, having in-plane full width half maximum (FWHM) resolution of approximately 15 mm. SPRINT acquisition of image data was performed using both the high resolution and high sensitivity apertures, with data collection over 15 or 20 minutes of imaging time accumulating approximately 500,000 counts and 1,000,000 counts, respectively, from patients in a 10.0 mm thick slice, achieving an in-plane FWHM resolution of approximately 8 mm and 10 mm for the two apertures, respectively. Both image resolution and contrast for visualization of gray, white, and cerebral spinal fluid filled brain structures were improved using SPRINT compared with the GE-400AC. We conclude that SPRINT is well suited for brain imaging with Tc-99m HMPAO and is of particular value for applications demanding high resolution. 相似文献
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