Quantitative Assessment of Left Ventricular and Left Atrial Functions by Strain Rate Imaging in Diabetic Patients with and without Hypertension
ABSTRACT Background: Impaired left ventricular (LV) function is shown by strain rate (SR) imaging in patients with diabetes mellitus (DM). Left atrium (LA) function in patients with DM, however, has not been assessed by this method and the effect of hypertension (HT) on LV and LA functions in diabetic patients has not been fully studied. The aim of this study was to quantitatively assess LA function in diabetic patients with and without HT in combination with LV function. Methods: Conventional echocardiographic and SR imaging studies were performed in 55 subjects with normal systolic LV function (LV ejection fraction of 55% or more) and no evidence of coronary artery disease: 17 with DM (DM group), 22 who have both DM and HT (DM+HT group), and 16 age-matched controls. SR imaging was performed from three apical views, and peak SR was measured at 12 LV segments and 5 LA segments. Mean peak systolic SR (LVs and LAs, respectively), early diastolic SR (LVe and LAe, respectively) and late diastolic SR (LVa and LAa, respectively) were calculated by averaging data in each LV and LA segment. Results: Despite no significant differences in age, LV ejection fraction and E/A ratio among the three groups, systolic blood pressure, LA dimension and LV mass index in the DM+HT group were significantly larger than those in the controls. The DM group had reduced systolic and diastolic LV functions and impaired LA reservoir and conduit functions compared with those in the controls, as shown by lower LVs (P < 0.05), LVe (P < 0.01), LAs (P < 0.01), and LAe (P < 0.05). The DM+HT group had reduced LVs (P < 0.01), LVe (P < 0.01), LAs (P < 0.01) and LAe (P < 0.01) compared with those in the controls. The DM+HT group had significantly lower LVe (P < 0.05) and LAe (P < 0.05) than did the DM group. Conclusions: SR imaging can detect impairment of LA reservoir and conduit functions as well as LV systolic and diastolic dysfunctions in patients with DM, even in the absence of LV hypertrophy and LA dilatation. Coexisting HT augments the impairment of LV diastolic and LA conduit functions in diabetic patients.
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ABSTRACT: The left atrium modulates left ventricular filling with its reservoir, conduit, and contractile functions. There is growing literature on the importance of a detailed assessment of left atrial function. This review article discusses the echocardiographic assessment of left atrial function by conventional parameters such as atrial size measurements, transmitral and pulmonary Doppler flow, mitral annular tissue velocities, as well as newer techniques such as regional strain and strain rate imaging by color tissue Doppler imaging and two-dimensional speckle tracking techniques. The clinical applications of these techniques in various conditions are discussed. KeywordsSpeckle tracking-Color tissue Doppler-Atrial fibrillation-Left atrial function-Left atrial volume-Doppler echocardiographyCurrent Cardiovascular Imaging Reports 3(5):276-285. DOI:10.1007/s12410-010-9041-9
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ABSTRACT: The authors present research on alternative basic elements for neural network modeling. A principle that has emerged from this research, which may have important implications for understanding natural and perhaps artificial intelligence, is examined. A paradigm that deals with what and when may be essential for modeling natural intelligence. The authors call such a paradigm a spatio-temporal neural network paradigm. Such a paradigm, which emphasizes real-time, closed-loop interactions between a learning system and its environment, is emerging from research on alternative models of single neuron function. In particular, it is found that neuronal models of classical conditioning phenomena and neural network models of instrumental conditioning phenomena suggest that, as a general principle, real-time considerations may be fundamental to natural intelligence. More specifically, the authors are investigating the hypothesis that learning in biological systems consists of acquired positive and negative real-time feedback loops built on a foundation of innate positive and negative real-time feedback loopsNeural Networks, 1989. IJCNN., International Joint Conference on; 07/1989
Conference Paper: Integrated services digital network voice data manager[Show abstract] [Hide abstract]
ABSTRACT: A discussion is presented of the integrated services digital network (ISDN) voice-data manager (IVDM) application being researched by the PC division of the National Cash Register (NCR) Corporation, Dayton, Ohio. This application is geared toward taking full advantage of the basic and supplementary voice services and basic data services (file transfer, screen transfer, etc.). The various implementation level issues of IVDM which runs under the multitasking environment offered by OS/2, are examinedTENCON '89. Fourth IEEE Region 10 International Conference; 12/1989