1,721,305 research outputs found
The role of sestamibi scintigraphy in the radioisotopic assessment of myocardial viability
No full textLeft Ventricular Dimensions and Perfusion in Hypertensive Patients with Positive Exercise Test and Angiographically Normal Coronary Arteries
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The clinical usefulness of electrocardiogram-gated Tc-99m methoxy-isobutyl-isonitrile images in the detection of basal wall motion abnormalities and reversibility of stress induced perfusion defects.
No full textComparative Study of myocardial ischaemia during angina at rest and on exertion using Thallium-201 scintigraphy
No full textRegional myocardial blood flow during pacing tachycardia in patients with arterial hypertension: The effect of therapy
No full textBackground. Patients with essential arterial hypertension (EH) demonstrated abnormal vasodilator capacity either during increase in cardiac metabolic demand or during pharmacological vasodilatation. Morpho-functional damage to coronary microcirculation has been advocated as one of the major causes of impaired coronary flow reserve in this disease. Methods and results. To evaluate the role of microvascular impairment on regional myocardial blood flow (MBF) distribution, 16 patients with EH were evaluated by dynamic positron emission tomography (PET) and 13N-ammonia at rest and during atrial pacing (AP); their findings were compared with 8 normal subjects. In a subgroup of 10 patients the study was repeated after 6 months of antihypertensive therapy with calcium-channel blockers or angiotensin-converting enzyme inhibitors as part of a randomized, single blind pharmacological trial. The PET evaluation was performed after that therapy was discontinued for a week, to allow recovery of blood pressure at levels comparable with the pre-treatment study. All patients had normal coronary arteries, 10 had left ventricular hypertrophy by echocardiographic criteria, while 6 did not. Baseline mean MBF in patients with EH was not significantly different from control group (0.97 ± 2.7 ml/min/g and 0.94 ± 1, respectively, ns), significantly increased to 1.69 ± 42 during AP (p < .01); however, mean flow during AP was significantly lower than in controls (2.15 ± 73 ml/min/g; p < .01). MBF response to AP was similarly depressed in both hypertrophic and non-hypertrophic patients. Antihypertensive therapy in 10 patients significantly improved the MBF response to pacing tachycardia (1.6 ± 39 ml/min/g pre-treatment vs 2.06 ± 65 ml/min/g post treatment, p < .05), in absence of changes in left ventricular mass or in metabolic demand. Conclusions. An obvious impairment of MBF during pacing tachycardia was observed in EH patients with normal coronary arteries, apparently unrelated to the presence of myocardial hypertrophy. Antihypertensive therapy with calcium-channel blockers or angiotensin-converting enzyme inhibitors was able to normalize MBF values during tachycardia. PET allowed identification of early abnormalities in coronary microvascular function
Myocardial blood flow and perfusion reserve in infarcted patients with stress-induced normalization of previously negative T waves: a positron emission tomography study.
No full textQuantitation of regional myocardial blood flow and coronary reserve in hypertensive patients by positron emission tomography
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