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Unstable angina and non Q-wave myocardial infarction. Early risk stratification: Role of silent ischemia and coronary morphology
No full textNo abstract availabl
Myocardial infarct with normal coronary vessels: an association with dysfunction of the coronary microcirculation
No full textThe association of acute myocardial infarction (AMI) with normal coronary arteries was analyzed prospectively. A series of 128 consecutive patients underwent coronary angiography within 1 week from AMI. Seven patients, all females, had no coronary artery lesions and were considered eligible for the study. All 7 patients underwent atrial pacing (10 g/min increments every 2 min), ergonovine testing (E; total dose 0.650 mg i.v.). Great cardiac vein flow (GCVF; thermodilution technique), mean aortic pressure (MAP), anterior coronary resistance (ACR) and myocardial lactate extraction [(Lac art-Lac gcv)/Lac art] were measured at baseline and during testing. Pacing-induced typical chest pain occurred in 5 patients: 4 of them showed concurrent significant (> or = 0.15 mV) ST downsloping. At peak pacing, GCVF increased only by < 50%, or even decreased, in all patients. Baseline lactate extraction (0.13 +/- 0.11) changed to lactate production (-0.15 +/- 0.10) in 7/7 patients. None of the patients showed focal epicardial coronary artery spasm following E. During testing, however, all 7 patients showed decrease in GCVF (110 +/- 47 versus 74 +/- 21; p < 0.005), increase in ACR (0.92 +/- 0.29 versus 1.43 +/- 0.20; p < 0.001), and significant coronary lactate production (-0.18 +/- 0.12). Six patients referred slight to moderate chest pain, which was accompanied by ST downsloping in 4.(ABSTRACT TRUNCATED AT 250 WORDS
The noninvasive identification of patients with angina and normal coronary arteries [Riconoscimento non invasivo dei pazienti con angina a coronarie normali.]
No full textBACKGROUND. Although patients with syndrome X (angina and normal coronary arteries, in absence of coronary spasm, cardiomyopathy or valvulopathy) and those with stable angina as well as documented coronary artery disease share a similar clinical presentation (effort related symptoms, positive exercise stress testing and reversible perfusion defects), their prognosis is markedly different. Coronary atherosclerosis is usually progressive relative to morbidity and mortality. Conversely prognosis both in terms of persistence of pain and mortality appears to be benign in syndrome X. Most cardiologists favor proceeding with coronary angiography in all patients presenting with exercise induced ST depression and reversible perfusion defects. However, it should not be assumed that this strategy will remain the preferred one. The aim of this study was to assess whether non invasive testing could identify underlying coronary artery anatomy, thus prognosis in the above subset of patients. The approach was selected on a clearly stated objective of how isosorbide dinitrate and verapamil may influence coronary flow reserve, thus exercise stress testing in syndrome X. Nitrates have been shown to reduce coronary flow reserve during stress tachycardia. The opposite occurs with calcium blockers. METHODS. We studied 48 patients with effort angina referred to our laboratory for diagnostic evaluation. All patients underwent two separate sessions at one-day interval. Each session consisted of exercise stress testing before and after isosorbide dinitrate (s.l.; 5-10 mg) or verapamil (i.v.; 10 mg), given in a randomized crossover fashion. Angiography was performed within 3 months from testing. Efficacy of drugs in terms of exercise capacity was assessed by using the following criteria: 1) prevention of significant (> or = 0.1 mV) ST depression while reaching same workload levels attained during baseline testing; 2) improvement in the ischemic thresholds, that is an increase in: time to 0.1 mV ST depression > or = 120 sec., with heart rate (> or = 10 bpm) and rate pressure product (> or = 2 U x 1000) greater than those attained during baseline testing; 3) increase in time to peak exercise (> or = 120 sec). RESULTS. In syndrome X, both drugs resulted ineffective in one patient, one patient showed a favourable response to isosorbide dinitrate whereas the remaining 13/15 patients improved exercise capacity following verapamil, but not isosorbide dinitrate. The opposite occurred in coronary artery disease patients: both isosorbide dinitrate and verapamil were effective in 21/33 patients, and ineffective in 8/33 patients. The remaining 4 patients responded to isosorbide dinitrate but not to verapamil. CONCLUSIONS. 1) Verapamil, but not isosorbide dinitrate, improves exercise capacity in syndrome X; 2) this does not apply to patients with stable angina; 3) a favourable response to verapamil but not to isosorbide dinitrate is both a sensitive (86%) and specific (100%) method for identifying patients with angina and normal coronary arteries; 4) non invasive testing may select those effort angina patients who have to proceed directly to coronary angiography; 5) some patients with effort related angina may not require further investigation
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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