1,721,149 research outputs found
Role of coronary microvascular dysfunction in heart failure with preserved ejection fraction
Full text linkHeart failure with preserved ejection fraction (HFpEF) is one of the greatest unmet needs in modern medicine. The lack of an appropriate therapy may reflect the lack of an accurate comprehension of its pathophysiology. Coronary microvascular rarefaction in HFpEF was first hypothesized in an autopsy study that showed how HFpEF patients had lower microvascular density and more myocardial fibrosis than control subjects. This was later confirmed in vivo when it was noted that HFpEF is associated with reduced myocardial flow reserve (MFR) at single photon emission computed tomography (SPECT) and that coronary microvascular dysfunction may play a role in HFpEF disease processes. HFpEF patients were found to have lower coronary flow reserve (CFR) and a higher index of microvascular resistance (IMR). What is the cause of microvascular dysfunction? In 2013, a new paradigm for the pathogenesis of HFpEF has been proposed. It has been postulated that the presence of a proinflammatory state leads to coronary microvascular endothelial inflammation and reduced nitric oxide bioavailability, which ultimately results in heart failure. Recently, it has also been noted that inflammation is the main driver of HFpEF, but via an increase in inducible nitric oxide synthase (iNOS) resulting in a decrease in unfolded protein response. This review summarizes the current evidence on the etiology of coronary microvascular dysfunction in HFpEF, focusing on the role of inflammation and its possible prevention and therapy
Accessory Renal Artery Stenosis and Hypertension: Are These Correlated? Evaluation Using Multidetector-Row Computed Tomographic Angiography
No full textBackground: Renal artery stenosis may produce hypertension, and this condition is referred to as renovascular hypertension (RVH).
Purpose: To evaluate, by using multidetector-row spiral computed tomographic angiography (MDCTA), whether a relationship between accessory renal artery stenosis and hypertension may be hypothesized.
Material and Methods: 214 patients (142 males, 72 females; mean age 66 years) who had previously undergone an MDCTA to study the abdominal vasculature were retrospectively studied. Patients with renal artery stenosis (RAS) were excluded from this analysis. The patients were studied by means of a four-detector-row CT, and scans were obtained after intravenous bolus administration of 110–140 ml of a nonionic contrast material with a 3–6 ml/s flow rate. As a second step, by means of statistical analysis, hypertension data were compared with findings of accessory artery stenosis. Two radiologists first independently reviewed the MDCTA images and then, in case of disagreement, in consensus. Interobserver agreement was calculated for all measurements.
Results: The overall number of detected accessory renal arteries was 74 in 56 of the 214 patients. Accessory renal artery stenosis was detected in 21 of the 56 patients. There was a difference in the prevalence of hypertension between patients with (n = 21) and without (n = 35) accessory renal artery stenosis (P = 0.0187). Interobserver agreement was good (kappa value 0.733).
Conclusion: Any statistical association between the presence of accessory renal artery stenosis and hypertension could not be disclosed. However, accessory renal artery stenosis, detected by MDCTA, is an important pathological sign that the radiologist has to assess in the light of its possible association with hypertension
Multidetector-row CT angiography diagnostic sensitivity in evaluation of renal artery stenosis: comparison between multiple reconstruction techniques
No full textPURPOSE: The aim of this study was to assess the image quality and interobserver agreement of various multidetector-row computed tomographic angiography postprocessing techniques in the diagnosis of renal artery stenosis (RAS).
MATERIALS AND METHODS: We studied 36 patients (21 men and 15 women; mean age, 49 years) who underwent computed tomography angiography to assess renal arteries for suspected RAS. Patients were analyzed by using a multidetector-row computed tomography. Computer tomographic scans were obtained after intravenous bolus administration of 110 to 140 mL of nonionic contrast material using a 4- to 6-mL/s flow rate. We assessed every patient by using axial scans, multiplanar reconstruction (MPR), maximum intensity projection (MIP), and volume rendering (VR) techniques. For each patient and for each reconstruction method, the image quality of the main renal artery was scored as 0 for bad-quality, 1 for poor-quality, 2 for good-quality, and 3 for excellent-quality images. Two radiologists reviewed computed tomographic images independently. We calculated interobserver agreement and kappa value. We correlated the stenosis degree observed by the 2 readers with the type of reconstruction used.
RESULTS: Overall number of renal arteries studied was 72, and we detected 24 RAS. Quality images obtained an overall (averaged between the 2 observers) value of 133 of 216, 163 of 216, and 145 of 216 for MPR, MIP, and VR, respectively. Our data underlined a statistical difference between MPR images and VR images (P < 0.001). Moreover, we noticed that the images classified as excellent were obtained from a vessel with 350 Hounsfield units or higher. Kappa value was good in MIP and VR methods evaluation but poor with the use of MPR.
CONCLUSIONS: Reformatting techniques usually provided a high visual impact, and in our study, MIP and VR showed the best diagnostic interobserver agreement in quality and reproducibility of stenosis degree
Effects of acute ischaemia on intramyocardial contraction heterogeneity. New technologies to study an old phenomenon.
No full textIF 5.15
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
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