Quantitative Assessment of Left Ventricular and Left Atrial Functions by Strain Rate Imaging in Diabetic Patients with and without Hypertension
(Impact Factor: 1.25).
11/2008; 26(3):262 - 271. DOI: 10.1111/j.1540-8175.2008.00805.x
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.
Available from: PubMed Central
- "The finding indicated diastolic strain rate might be more sensitive to impaired left ventricular diastolic function. Muranaka et al
 demonstrated that early diastolic circumferential strain rates were reduced in diabetic patients using strain rate imaging. Wei Z et al
[8,9] reported that 12 weeks after STZ induction, circumferential diastolic strain rates of the mid-level wall decreased mildly from 3.53-1 to 2.47-1. "
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To clarify the time-course changes in left ventricular myocardial deformation using velocity vector imaging and to provide insights into our understanding of the cardiac pathophysiology in diabetes mellitus.
Thirty New Zealand white rabbits were randomly divided into either the control group (n = 10) or the diabetes mellitus (DM) group (induced with STZ, n = 20). For the myocardial deformation studies, echocardiography and syngo-vector velocity imaging (VVI) were performed at baseline and after 2, 4, 8, and 12 weeks in all of the rabbits. The left ventricular (LV) global longitudinal and circumferential strain and strain rate were measured. For histomorphological study of the heart structure, 2 of the STZ-induced rabbits were killed at 2, 4, 8, and 12 weeks. Routine hematoxylin and eosin staining was performed.
At 2 weeks, the global longitudinal strain (GLS), systolic strain rate (GLSRs), and diastolic strain rate (GLSRd) were significantly lower in the DM group compared with the control group (-18.16% versus -24.00%, -1.86 s-1 versus -2.49 s-1, 1.93 s-1 versus 2.42 s-1, respectively, P < 0.05), while, compared with the control group, the global circumferential strain (GCS), systolic strain rate (GCSRs), and diastolic strain rate (GCSRd) in the DM group were significantly decreased (-12.77% versus -23.31%, -1.31 s-1 versus -2.20 s-1, 1.41 s-1 versus 2.15 s-1, respectively, P < 0.05) at 8 weeks. With the progression of untreated diabetes, the histoanatomical alterations intensified gradually beginning at 2 weeks.
The progressive impairments in LV myocardial deformation and structure occurred early in diabetic rabbits with normal LV ejection fraction (EF), FS, and E/A. VVI could be used to evaluate subtle cardiac dysfunction in the early phase of DM.
Available from: Sang-Hyun Ihm
- "Thus, both the utility and reproducibility of this method were validated. Second, many clinical conditions, such as hypertension, diabetes mellitus and atrial fibrillation, were studied using this technique and the clinical implications developed from previous studies.13-15)22) Third, all the parameters representing various functions of the LA can be measured from one imaging. "
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ABSTRACT: Non-dippers were reported as showing different left atrial function, compared to dippers, but no study to date investigated the changes in the left atrial function according to the diurnal blood pressure pattern, using tissue Doppler and strain imaging.
Forty never treated hypertensive patients between 30 and 80 years of age were enrolled in this study. Patients were classified as non-dippers when, during night time, they had a blood pressure decrease of less than 10%. Strain of the left atrium was measured during late systole, and peak strain rates of the left atrium were measured during systole, early and late diastolic periods.
The left atrial expansion index, left atrial active emptying volume and left atrial active emptying fraction were all significantly increased in non-dippers. They also had increased values of mean peak left atrial strain (dippers = 21.26 ± 4.23% vs. non-dippers = 24.91 ± 5.20%, p = 0.02), strain rate during reservoir (dippers = 1.29 ± 0.23 s(-1) vs. non-dippers =1.52 ± 0.27 s(-1), p = 0.01) and contractile period (dippers = -1.38 ± 0.24 s(-1) vs. non-dippers = -1.68 ± 0.32 s(-1), p < 0.01).
Strain and strain rate acquired from color Doppler tissue imaging demonstrate exaggerated reservoir and booster pump function in never-treated, non-dipper hypertensive patients. These methods are simple and sensitive for the early detection of subtle changes in the left atrial function.
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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 loops
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