Simpson's Method Research Articles

Further Acceleration of the Simpson Method for Solving Nonlinear Equations

There are two aims of this paper, firstly, we present an improvement of the classical Simpson third-order method for finding zeros a nonlinear equation and secondly, we introduce a new formula for approximating second-order derivative. The new Simpson-type method is shown to converge of the order four. Per iteration the new method requires same amount of evaluations of the function and therefore the new method has an efficiency index better than the classical Simpson method. We examine the effectiveness of the new fourth-order Simpson-type method by approximating the simple root of a given nonlinear equation. Numerical comparisons is made with classical Simpson method to show the performance of the presented method.

A stable gravity downward continuation for structural delineation in Sulu Sea region

We have presented a discrete equivalent source method to perform a stable gravity downward continuation for structural delineation in the Sulu Sea region. Our method automatically selects an effective small amount of the discrete sources by using the modified Blakely and Simpson's method. It tests whether each observed gravity is minimum or maximum relative to the neighbouring eight points, then assigns the coordinates to one discrete source. This procedure reduces the coefficient matrix size. Moreover, the method assumes each source as a point source instead of rectangular prism to reduce model parameters. Then, it iteratively searches an optimum solution and the corresponding depth by simultaneously using both the CG and Golden Section Search algorithms. The optimum solution and the corresponding depth are then used to compute the downward continued gravity field. Testing on synthetic data confirmed the efficiency of our method in performing stable downward continuation. The method is also appropriate for computing gravity upward continuation, potential field on a plane or an uneven surface, and centroid depths of causative sources. A combination of both the downward continuation and an effective boundary detection technique delineated several faults and volcanic/intrusive rocks in the Sulu Sea region. These structure were formed by plate movement, subduction and collision. Finally, the reoriented structures along the dextral strike-slip fault that passes though the Sulu Sea and Sulu ridge was attributed to the increasing speed of the Philippine plate towards the north.

Assessment of left ventricular ejection fraction with late-systolic and mid-diastolic cardiac phases using multi-slice computed tomography

IntroductionMulti-slice computed tomography (MSCT) is an accurate tool for the assessment of left ventricular ejection fraction (LVEF). However, in order to reduce radiation dose, prospective acquisition protocols are currently used, in which the end-systole and end-diastole are not scanned. Our aim was to study the accuracy of the assessment of LVEF using fixed late-systolic and mid-diastolic cardiac phases compared with echocardiography. MethodsMSCT-derived LVEF was measured with off-line commercially available software packages, and compared with echocardiography-derived LVEF using the Simpson's method. LVEF was categorized as normal vs. abnormal (50% cut-off) and was also analyzed as a quantitative parameter. Bland-Altman plots and Pearson correlations were used for inter-technique comparisons. Results58 patients were included. The sensitivity and specificity of fixed-phase MSCT when compared with echocardiography for detection of LVEF ≤50% was 79% (95% CI = 65–89%) and 43% (10–82%). Misclassification was associated with older age (68 ± 12 vs. 54 ± 13 years, p < 0.01), faster heart rate (79 ± 14 vs. 68 ± 10 bpm, p = 0.01), and LV hypertrophy (86% vs. 52%, p = 0.03). The quantitative comparison revealed no correlation (r = 0.095, p = 0.478) and a significantly different LVEF (median[IQR], 57.0[50.5–63.1]% vs. 61.0[57.3–64.3]%, p = 0.03). The observed bias between the two methods was −3.7% with broad limits of agreement (±25.5%). ConclusionsFixed-phase MSCT assessment using late-systole and mid-diastole agreed in defining normal and abnormal LVEF in 76% of patients when compared with echocardiography. Quantitation of LVEF by this method yielded significantly lower values of LVEF and showed no correlation. Thus, accurate quantitation of LVEF by MSCT requires the acquisition of end-systolic and end-diastolic phases.

Echocardiographic Analysis of Cardiac Function after Infarction in Mice: Validation of Single-Plane Long-Axis View Measurements and the Bi-Plane Simpson Method

Although echocardiography is commonly used to analyze cardiac function in small animal models of cardiac remodeling after myocardial infarction, the different echocardiographic methods are validated poorly. End-diastolic volume, end-systolic volume and ejection fraction were analyzed using either standard single-plane analysis from parasternal long-axis B-mode views (PSLAX) or the bi-plane Simpson method (using PSLAX and three short-axis views) and validated using magnetic resonance imaging as standard. Ejection fraction measured by PSLAX was moderately correlated with a coefficient of R2 = 0.49. The standard deviation of residuals was 9.91. Simpson analysis revealed an improved correlation coefficient of R2 = 0.77 and a reduction in standard deviation of residuals by 45% (5.45 vs. 9.92, p = 0.014). Subgroup analysis revealed that the high variation in PSLAX is due to changes in ventricular geometry after myocardial infarction. Our results indicate that the bi-plane Simpson method is advantageous for the assessment of cardiac function after myocardial infarction.

Use of speckle tracking in the evaluation of late subclinical myocardial damage in survivors of childhood acute leukaemia.

Heart disease is the leading cause of non-cancer death in childhood cancer survivors. to determine the prevalence of subclinical cardiac dysfunction using speckle tracking and compare its results with those obtained by classical methods of assessing left ventricular function and its relationship with different factors to identify the population at higher risk. Echocardiographic assessment of left ventricular function included ejection fraction, tissue Doppler, longitudinal/circumferential strains and biochemical parameters (troponin-T and Pro-BNP) in a cohort of 57 survivors of childhood acute leukaemia with at least 10years since diagnosis. Ventricular dysfunction was found in 5.2% of patients in M-mode (ejection fraction-EF < 53% with a reduction in the EF ≥ 10%) and in 7% of patients with Simpson's method, compared with 21.05 and 8.8% with suboptimal global longitudinal strain (GLS) and global circumferential strain, respectively. The GLS alteration was significantly correlated with lower values of left ventricular systolic function and was associated with high tumour risk (odds ratio [OR] 13.8), cumulative doses of anthracyclines ≥ 250mg/m2 (OR 7.6) and radiotherapy (OR 7.19). Biomarkers were not useful for the diagnosis of subclinical cardiomyopathy. Good reproducibility was obtained, with an intraobserver correlation of 93.6% and an interobserver correlation of 89.2% in the GLS. The alteration of the GLS was more prevalent than the alteration in the EF and was associated with the treatment received and high tumour risk. strain imaging seems to be a powerful tool to identify an increased number of survivor with an early myocardial injury.

An analysis of MATLAB's software performance interfaced with high-level C language for expediting numerical integration technique

In this work custom functions are embedded in the MATLAB environment and performance is analyzed with respect to time and space. These functions fall into two categories: 1) those developed using MATLAB's scripting language; and 2) those implemented in C and compiled into functions executable in MATLAB. This work focuses exclusively on expediting three of the most common numerical integration techniques (the Trapezoidal Rule, Midpoint Rule, and Simpson's Method) as an initial step with hopes of gaining insight into the feasibility of implementing such an approach on ordinary differential equation (ODE) solvers.

Utility of 128-row multidetector CT in quantitative evaluation of global left ventricular function in patients with coronary artery disease

PurposeIs to compare the role of 128 MDCT in quantitative evaluation of left ventricle function in patients with coronary artery disease compared to 2D echocardiography. Patients and methodsFifty patients with suspected coronary artery disease underwent contrast enhanced MDCT using retrospective gating without dose modulation. Ten phases of cardiac cycle were processed to assess end-systolic and end-diastolic phase at LV short-axis view. 2DSE was performed in the same day. LVSV, LVDV, LFEF, LVSV were calculated using the Simpson's method in MDCT and modified Simpson's method in echocardiography. ResultsLVSV, LVDV, LVSV, LFEF were 74.30 ± 24.92, 185.46 ± 56.25, 84.15 ± 33.16, 48.88 ± 13.32 respectively on MSCT and 71.43 ± 21.93, 182.31 ± 56.49, 81.74 ± 32.88, 47.82 ± 13.64 respectively on echocardiography with excellent correlation between the modalities (P < 0.001) using linear regression analysis. A Bland-Altman analysis showed that MDCT had slightly higher LVSV, LVDV, and LVSV, LFEF values with mean value of differences of 2.9, 3, 2.4 and 1% respectively. ConclusionMDCT is an accurate method for quantitative evaluation of global left ventricular function compared to 2D echocardiography.

Tumour model with intrusive morphology, progressive phenotypical heterogeneity and memory

The model of a tumour, taking into account invasive morphology, progressive phenotypical heterogeneity and also memory, is developed and analyzed in this paper. Three models are investigated: first we consider the model describing the proliferation concentrates in proximity of tumour boundaries, in which the oxygen levels are pronounced. Then we consider the model where the oxygen around the tumour is considered to be unchanged by the vascular system. Finally, we investigate the model of growth of tumours using the concept of non-local operators with the Mittag-Leffler kernel. We provide the numerical solution using the extended 3/8 Simpson method for the new trends of fractional integration for the proliferation concentrates in the proximity of the tumour model. Then we provide the exact solutions of the Gompertz model with three different fractional differentiations involving power law, exponential decay law and the Mittag-Leffler law.

Comparation of Magnetic Flux Cases Solution in Around Electrified Wire between Analytical and Computational Methods

Have analyzed comparative analytical and numerical computation solutions in the case of magnetic flux to the circular loop of radius R as far apart as H around the current I in the wire. The aim is to know how the methods used have an accurate solutions calculated based on relative error value. The analytical method use taking concept of polar coordinates and the computational method using the function of analytic equations modified based on Simpson and Monte Carlo method. Both methods are aprroaches in numerical integration.After test with variation of combination of R=0.1 and 0.2 and H=0.1 and 0.2, the Simpson and Monte Carlo indicate the integration value corresponding to the exact or analytical solution value, the relative error value of the Simpson method range from 0,004% - 0,017% and the relatif error value for Monte Carlo method range from 0.056% - 3.4296%.&#x0D; Keywords: magnetic flux, analytical, simpson, monte carlo, relative error

Error analysis of time-domain methods for milling stability prediction

Stability prediction is an efficient way to avoid milling chatter which is one of the major limitations in increasing efficiency of milling operations. Since Insperger et al. [1] presented the semi-discretization methods (SDM) and demonstrated that the local discretization error is o(h3), in order to increase prediction accuracy, full-discretization methods (FDMs) [2,3], Simpson method [4] and spectral methods [5,6] etc. are proposed. These methods use polynomial interpolation to approximate the original system. The prediction errors are always analyzed based on Taylor expansions. Mathematically, the error analysis based on Taylor’s theorem requires that the original function has continuous derivatives of equivalent orders, that is, if a k-order polynomial interpolation is adopted, the original function must have continuous k-order derivatives [7]. However, milling operation is a highly interrupted cutting process, and the accelerations at the moments where cutter tooth enters and exits of the cut are obviously not continuous. Thus, even the order of local error at somewhere is rather high, the global error is not improved yet, and it may cause nonuniform convergence. In this paper, problems are revealed through simulations with specific milling parameters. It is concluded that the accuracy of the representative time-domain methods can hardly reach as high as o(h3). Moreover, the discretization scheme to overcome the problems and improve applicability of the existing methods is also discussed.

Early diagnosis of cardiac involvement in systemic lupus erythematosus via global longitudinal strain (GLS) by speckle tracking echocardiography.

Introduction: Systemic lupus erythematosus (SLE) myocarditis occurs in between 5% and 10% of patients with lupus. Global longitudinal strain (GLS) via speckle tracking echocardiography can detect cardiac involvement in patients suffering from SLE. We decided to determine the echocardiographic features and subsequent early diagnosis of cardiac involvement in patients with SLE utilizing the GLS index via speckle tracking echocardiography. Methods: In this cross-sectional study, we compared female patients with SLE of at least 2 years’ duration and healthy controls in terms of the left ventricular (LV) GLS via speckle tracking echocardiography. After data collection in both groups, the GLS index and the ejection fraction were evaluated. Results: We analyzed and compared the LV echocardiographic parameters of 33 patients with SLE (mean age=25.45±0.63 years) with those of 35 healthy controls (mean age=27±0.45 years). The apical 2-chamber view indicated a significant decrease in the LV GLS in the case group by comparison with the healthy controls (P=0.005). The LV GLS in the apical 3-chamber view was significantly lower in the case group than in the control group (P=0.006). The LV GLS in the apical 4-chamber view revealed no significant difference between the case and healthy control groups (P=0.2). While there was a significant difference between the case and control groups visà- vis the LV GLS (P=0.02), the LV ejection fraction measured with the Simpson method showed no significant difference between the 2 groups (P=0.96). Conclusion: GLS speckle tracking echocardiography is a noninvasive method with diagnostic and prognostic values; it may, therefore, be a sensitive marker for the diagnosis of myocarditis and other cardiac involvements in patients with SLE.

Feasibility and reproducibility of new 3D automatic software for left heart chamber quantification in children

New 3D automatic software (Heart model (HM), Philips Healthcare, Andover, Massachusetts) is now available to quantify left heart chamber size and function. Its feasibility and accuracy in children have not been reported. The aim of this study was to assess feasibility and reproducibility of HM in healthy children, and to compare LV indices obtained by this technique with classic 2D biplane method. Sixty consecutive healthy children aged more than 5 years were included (mean age 6.5 years, mean weight 20.8 kg). All infants underwent TTE (Epic 7, X5-1, Philips Healthcare, Andover, Massachusetts). Left ventricle (LV) end-systolic and end-diastolic volumes, LV ejection fraction (EF) and left atrium (LA) end-systolic volume were obtained by biplane Simpson method. 3D dataset was obtained from apical 4-chamber view and analyzed using HM software. LV indices obtained by the two methods were compared. Feasibility of HM was 80%, in 30 cases (62.5%) with contour adjustment and 18 cases (37.5%) without contour adjustment. Intraobserver variability was (0%, 4% and 8% for HM without contour adjustment, HM with contour adjustment, and biplane method respectively). Interobserver variability was (6% and 12% for HM with contour adjustment and biplane method respectively). Test- retest variability for HM was 6.5%. Correlation between HM and biplane measurements was strong ( r = 0.85 to 0.94). LVEF obtained by HM was lower than that obtained by biplane method (bias −8%). However, LV volumes and LA end-systolic volume were larger (bias +12 and +8 respectively) ( Fig. 1 ). HM is a promising software for assessment of left heart chamber volume and function. Its feasibility in infants aged more than 5 years is good with excellent reproducibility. Working is going on to validate this technique in children with congenital heart disease and to compare it with MRI measurement as the gold standard.

Assessment of the study of longitudinal systolic function by 2D strain in hypertensive patients with preserved LVEF

Hypertension is a risk factor for cardiovascular disease. It causes LV hypertrophy (LVH). LVH as well as patterns of abnormal geometry have been associated with adverse outcomes. Global longitudinal strain (GLS) has been used to detect early subclinical myocardial dysfunction in a broad spectrum of cardiac conditions and provides a novel approach for LV risk assessment in patients with hypertension. Assess the clinical and echocardiographic factors associated with and predictive for early impairment of left ventricular function as assessed using GLS evaluation in hypertensive patients. Cross-sectional descriptive study, with a number of 130 hypertensive and with the objective of evaluating the study of longitudinal function by 2D strain in patients with systemic hypertension with preserved LVEF and the determination of predictors factors of the decrease GLS in this population. A complete study echo cardiographic, including LVEF biplane Simpson method, calculation of left ventricular mass indexed and relative parietal thickness, analysis diastolic function and the study of longitudinal strain of the LV. The prevalence of (LVH) was 66%. 49% presented a concentric hypertrophy, 73% had a relative wall thickness (RWT) > 0.42.18% had severe diastolic dysfunction with elevation in filling pressure. The mean GLS was found to be −16.9 ± 3.2%, low GLS values (> −17%) were found in 45.5% of the general population. In particular, 34.4% of the patients had no LVH and 50.7% of them presented LVH. Statistical analysis revealed significant correlation between the decrease in GLS and diabetes, the values of blood pressure and elevated filling pressures. The evaluation of longitudinal systolic function by 2D strain provides new insight of myocardial function in hypertension that could improve the pathophysiological understanding and identify high-risk heart failure patients eligible for preventive strategies.

Variability of left ventricular volume and ejection fraction measurements using contrast echocardiography: The influence of the left ventricular length measurements in a large cohort of patients during monitoring cardiotoxic effects of chemotherapy.

To investigate the influence of length difference in left ventricular (LV) long axis between the apical four-chamber and two-chamber views on measurements of LV volumes and ejection fraction (EF). Seven hundred consecutive cancer patients underwent contrast echocardiography from July 2010 to May 2014. All patients received the echocardiographic contrast agent Definity. Recordings of apical views were analyzed by a sonographer and then by a cardiologist. The end-diastolic and end-systolic LV volumes (EDV and ESV), and LV lengths as well as EF, were measured using the biplane Simpson's method. Inter-observer variability was assessed using relative mean error (RME) and Bland-Altman analysis. Six hundred ninety-two patients had contrast echocardiograms with complete endocardial definition. The LV length difference of the long axis measured by the cardiologist was ≤1mm in 284 studies (41%), 2mm in 146 studies (21%), 3mm in 103 studies (15%), and ≥4mm in 159 studies (23%). The limits of agreement (LOA) and RME increase with the increasing length difference. Compared to the groups with length difference <4mm, the RME of the measurements of indexed EDV, indexed ESV, and EF was significantly greater in the group with length difference ≥4mm (P<.05). These results highlight the need for reviewing the LV long axis length measurements in order to provide reproducible LV volumes and EF measurements and may be used as benchmarks for quality control. A length difference of ≤3mm can be achieved in most of our patients and is associated with an excellent inter-observer agreement.

Left atrial function and mortality in the oldest old.

Previous studies demonstrated that left atrium (LA) size is associated with mortality in an elderly population. It remains unclear whether indices of LA function including reservoir, conduit, or booster elements of LA function provide incremental prognostic information. Echocardiographic measures of the various parameters of LA function would predict 5-year mortality in a community-dwelling population of 85 to 86 year olds independently of LA volume. Subjects ages 85 to 86 years old underwent home echocardiography. LA volumes were assessed by the biplane Simpson's method from apical views using measurements of phasic volumes and functions of the LA, including LA expansion index. LA passive and active emptying fractions were assessed. Survival status at 5-year follow-up was assessed. Two hundred eighty-two subjects were included, of whom 87 (31%) had died at follow-up. Survival of the subjects in the lowest quartile of the LA expansion index as well as LA active filling index was significantly lower. When measurements of LA volume index were added to the model, the relationship between survival and indices of LA function remained significant. This study demonstrated that elderly subjects aged 85 to 86 years with significantly impaired LA function had increased 5-year mortality independently of indices of LA volume.

Correlations between anterior wall motion velocity of ascending aorta measured by quantitative tissue velocity image and left ventricular geometry as well as left heart function in hypertension patients.

This study aimed to analyze the correlations between anterior wall motion velocity of ascending aorta measured by quantitative tissue velocity image (QTVI) technique and left ventricular geometry as well as left heart function to evaluate its value of clinical application. One hundred ten hypertension patients and 35 healthy controls were included, divided into left ventricular concentric remodeling group and left ventricular hypertrophy group. The QTVI technique was used to obtain the velocity curve of anterior wall of ascending aorta, the peak systolic velocity (Vs), peak velocity of early diastolic motion (Ve) and peak velocity of late diastolic motion (Va). The single-plane Simpson method was utilized to measure the left ventricular ejection fraction (EF). The QTVI method was used to obtain the index of left ventricular diastolic function (Em/Am). Compared to control group, both Vs and Ve values significantly reduced in hypertension group (P<0.05). Both Vs and Ve values were significantly negatively correlated with LVMI and RWT (P<0.01). The Va value was negatively correlated with LVMI (P<0.05). The Vs value was significantly positively correlated with EF value (P<0.01). The Ve value was significantly positively correlated with both EF and Em/Am (P<0.01). The Va value was positive correlated with Em/Am (P<0.05). The QTVI anterior wall velocity of ascending aorta could be indicator for the geometric patterns and function of left ventricle, which may provide a simple and comprehensive method for clinical assessment of hypertensive heart disease.

Validity of automated measurement of left ventricular ejection fraction and volume using the Philips EPIQ system.

To assess the efficiency and reproducibility of automated measurements of left ventricular (LV) volumes and LV ejection fraction (LVEF) in comparison to manually traced biplane Simpson's method. This is a single-center prospective study. Apical four- and two-chamber views were acquired in patients in sinus rhythm. Two operators independently measured LV volumes and LVEF using biplane Simpson's method. In addition, the image analysis software a2DQ on the Philips EPIQ system was applied to automatically assess the LV volumes and LVEF. Time spent on each analysis, using both methods, was documented. Concordance of echocardiographic measures was evaluated using intraclass correlation (ICC) and Bland-Altman analysis. Manual tracing and automated measurement of LV volumes and LVEF were performed in 184 patients with a mean age of 67.3±17.3years and BMI 28.0±6.8kg/m2 . ICC and Bland-Altman analysis showed good agreements between manual and automated methods measuring LVEF, end-systolic, and end-diastolic volumes. The average analysis time was significantly less using the automated method than manual tracing (116 vs 217seconds/patient, P<.0001). Automated measurement using the novel image analysis software a2DQ on the Philips EPIQ system produced accurate, efficient, and reproducible assessment of LV volumes and LVEF compared with manual measurement.

Predicting Cardiotoxic Effects of Carbon Monoxide Poisoning Using Speckle Tracking Echocardiography.

Carbon monoxide (CO) poisoning could cause significant cardiac injury. This study aimed to evaluate patients with CO poisoning by using speckle tracking echocardiography (STE), a potentially more sensitive technique, to identify left systolic ventricular dysfunction for the first time in the literature. Seventy-two patients who were exposed to CO poisoning were studied. Blood collection and echocardiography were performed at admission and after patients' discharge on days 10-15 (mean 12days). Global longitudinal strain (GLS) and global circumferential strain (GCS) were calculated using STE. In order to find the normal strain levels and to compare it to the patient with CO poisoning, 35 healthy subjects were included in the study. Left ventricular ejection fraction was analyzed according to Simpson's method. Patients were divided into two groups based on their LVEF values. LVEF<55%, Group 1 (n=24); LVEF≥55%, Group 2 (n=48). The reduction in Group 1 strain levels decreased in correlation with LVEF (p<0.001) while in Group 2, there were no significant changes in LVEF but strain levels were significantly reduced (p=0.091; p<0.001). Compared with the control group patients, admission GLS and GLC values of CO-poisoned patients were significantly low both in Group 1 and 2. On the contrary, no significant difference was observed when compared with follow-up GLS value. For prediction of CO cardiotoxicity, the cutoff value of GLS was ≥ -19.1 with a sensitivity of 70.3% and a specificity of 100% [(AUC) 0.840, 95% (CI) 0.735-0.916; p<0.001] in the ROC curve analyses. GLS was found as independent predictors of cardiotoxicity. Our study demonstrates the potential of using systolic strain values obtained using 2D-STE in determining cardiotoxicity due to CO poisoning. Speckle tracking echocardiography has the potential of demonstrating subtle LV systolic dysfunction even in CO poisoning patients with preserved EF.

Impact of stroke volume assessment by integrating multi-detector computed tomography and Doppler data on the classification of aortic stenosis

BackgroundThe prevalence of low flow low gradient (LFLG) severe aortic stenosis (AS) may be overrated due to underestimation of stroke volume in two-dimensional (2D) echocardiography. The implications of 3D imaging on stroke volume calculation for AS classification have not been elucidated. Integrating multi-detector computed tomography (MDCT) and Doppler data may improve diagnostic accuracy in patients with LFLG AS. MethodsA total of 186 patients with severe AS evaluated for transcatheter aortic valve replacement were classified according to indexed stroke volume (SVI, cut-off 35mL/m2) and mean transaortic pressure gradient (cut-off 40mmHg). SVI was calculated using a) the biplane Simpson's method, b) left ventricular outflow tract (LVOT) velocity time integral (VTI) and LVOT diameter determined by 2D echocardiography, or c) LVOT VTI and LVOT area planimetered by MDCT. ResultsSVI assessed by the biplane Simpson's method was smaller than that obtained from 2D echocardiography LVOT diameter (29.5±0.6 vs 34.9±0.8mL/m2, p<0.001). The latter was smaller than SVI calculated by integrating MDCT and Doppler data (47.5±1.4mL/m2, p<0.001). LFLG and paradoxical LFLG severe AS were diagnosed in 42.5% and 27.4% of patients using the biplane Simpson's method, in 30.1% and 16.7% using 2D echocardiography LVOT diameter, and in 17.2% and 8.1% when integrating MDCT and Doppler data. ConclusionsThe prevalence of LFLG and paradoxical LFLG severe AS was overestimated by 2.5- and 3.4-fold based on 2D echocardiography alone. Integration of MDCT and Doppler data should be considered for stroke volume assessment in the classification of severe AS.

PP.04.01] LEFT ATRIUM FUNCTION IN SYSTEMIC ARTERIAL HYPERTENSION

Objective: Assessment of left atrium (LA) mechanic by 2-Dimensional Speckle tracking Imaging (STI) recently has been discussed as useful method for LA function estimation. The purpose of this study was to assess the relationship between LA function (particularly reservoir function) and LA structural remodeling in patients with systemic arterial hypertension. LA evaluation was made using conventional echocardiography, tissue Doppler, and 2-Dimensional STI. Design and method: 48 hypertensive patients without left ventricular hypertrophy and 36 healthy controls (age and gender matched), underwent routine transthoracic echocardiography and speckle tracking echocardiography of the left atrium. LA volume was calculated by the biplane Simpson's method. Peak early diastolic transmitral flow velocity, peak early diastolic mitral annular motion velocity (E/E1) and peak systolic LA strain were messured. Results: LV Mass was 132.7 ± 16.5 grams in control and 180.2 ± 60.4 grams in the hypertensive patients. Left atrium volume indexed to body surface area was 19.4 ± 5.4 versus 29.4 ± 4.3 ml/m2 in controls and hypertensive subjects respectively (p < 0.001). There were also significant differences between the measurements of transmitral flow velocities (E, A), and E/E1 and E/A ratios in both groups. Left atrium anteroposterior diameter was higher in the hypertensive group 4.20 ± 0.58 versus 3.4 ± 0.28 cm in the contols (p < 0.001). Left atrial longitudinal strain was 24.05 ± 3.18 in hypertensive patients and 32.7 ± 2.8 among controls (p < 0.001). Conclusions: Speckle tracking imaging might be assumed as method for early detection of LA function impairment in arterial hypertension.