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Longitudinal Strain (longitudinal + strain)

Distribution by Scientific Domains

Medical Sciences	90%

Distribution within Medical Sciences

Cardiovascular Disease	55%
Radiology & Imaging	33%

Selected Abstracts

Effect of Preload on Left Ventricular Longitudinal Strain by 2D Speckle Tracking

ECHOCARDIOGRAPHY, Issue 8 2008
Jin-Oh Choi M.D.
Background: Peak systolic longitudinal strain (PSLS) obtained using the 2D speckle tracking method is a novel indicator of the long-axis function of the left ventricle (LV). We used the 2D strain profile to examine the effect of preload reduction by hemodialysis (HD) on LV PSLS in patients with end-stage renal disease (ESRD). Method and results: Twenty-nine pairs of echocardiographic evaluations were obtained before and after dialysis. Global LV PSLS was ,18.4 ± 2.9%, at baseline and decreased to ,16.9 ± 3.2% after HD (P < 0.001). Segmental analysis showed that the decrease in PSLS after dialysis was most prominent in mid-LV segments (,17.1 ± 3.5% vs. ,15.4 ± 3.4%, P < 0.001). Conclusion: PSLS obtained from the 2D strain profile is a reliable parameter that may be useful for evaluating LV systolic long-axis function. However, PSLS should be applied cautiously in ESRD patients because it could be affected by dialysis. [source]

Strain-encoded (SENC) magnetic resonance imaging to evaluate regional heterogeneity of myocardial strain in healthy volunteers: Comparison with conventional tagging

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2009
Mirja Neizel MD
Abstract Purpose To evaluate the ability of strain-encoded (SENC) magnetic resonance imaging (MRI) for regional systolic and diastolic strain analysis of the myocardium in healthy volunteers. Materials and Methods Circumferential and longitudinal peak systolic strain values of 75 healthy volunteers (35 women and 40 men, mean age 44 ± 12 years) were measured using SENC at 1.5T. MR tagging was used as the reference standard for measuring regional function. Diastolic function was assessed in the 10 youngest (24 ± 8 years) and 10 oldest (62 ± 5 years) subjects. Results Peak strain values assessed with SENC were comparable to those obtained by MR tagging, showing narrow limits of agreement (limits of agreement ,5.6% to 8.1%). Regional heterogeneity was observed between different segments of the left ventricle (LV) by both techniques (P < 0.001). Longitudinal strain obtained by SENC was also heterogenous (P < 0.001). Interestingly, no age- or gender-specific differences in peak systolic strain were observed, whereas the peak rate of relaxation of circumferential strain rate was decreased in the older group. Conclusion SENC is a reliable tool for accurate and objective quantification of regional myocardial systolic as well as diastolic function. In agreement with tagged MRI, SENC detected slightly heterogeneous myocardial strain within LV segments. J. Magn. Reson. Imaging 2009;29:99,105. © 2008 Wiley-Liss, Inc. [source]

Association of Left Atrial Strain and Strain Rate Assessed by Speckle Tracking Echocardiography with Paroxysmal Atrial Fibrillation

ECHOCARDIOGRAPHY, Issue 10 2009
Wei-Chuan Tsai M.D.
Background: We hypothesized that contraction of the LA wall could be documented by speckle tracking and could be applied for assessment of LA function. This study tried to identify the association between LA longitudinal strain (LAS) and strain rate (LASR) measured by speckle tracking with paroxysmal atrial fibrillation (PAF). Methods: Fifty-two patients (61 ± 17 years old, 23 men) with sinus rhythm at baseline referred for the evaluation of episodic palpitation were included. Standard four-chamber and two-chamber views were acquired and analyzed off-line. Peak LAS and LASR were carefully identified as the peak negative inflection of speckle tracking waves after P-wave gated by electrocardiography. Results: Ten patients (19%) had PAF. LAS, LASR, age, left ventricular end-diastolic dimension, left ventricular mass, LA volume, and mitral early filling-to-annulus early velocity ratio were different between patients with and without PAF. After multivariate analysis, LASR was significantly independently associated with PAF (OR 8.56, 95% CI 1.14,64.02, P = 0.036). Conclusion: Speckle tracking echocardiography could be used in measurements of LAS and LASR. Decreased negative LASR was independently associated with PAF. [source]

Effect of Preload on Left Ventricular Longitudinal Strain by 2D Speckle Tracking

Effect of Angular Error on Tissue Doppler Velocities and Strain

ECHOCARDIOGRAPHY, Issue 7 2003
Camilla Storaa M.S.
One of the major criticisms of ultrasound Doppler is its angle dependency, that is its ability to measure velocity components directly to or from the transducer only. The present article aims to investigate the impact of this angular error in a clinical setting. Apical two- and four-chamber views were recorded in 43 individuals, and the myocardium was marked by hand in each image. We assume that the main direction of the myocardial velocities is longitudinal and correct for the angular error by backprojecting measured velocities onto the longitudinal direction drawn. Strain was calculated from both corrected and uncorrected velocities in 12 segments for each individual. The results indicate that the difference between strain values calculated from corrected and uncorrected velocities is insignificant in 5 segments and within a decimal range in 11 segments. The biggest difference between measured and corrected strain values was found in the apical segments. Strain is also found to be more robust against angular error than velocities because the difference between corrected and uncorrected values is smaller for strain. Considering that there are multiple sources of noise in ultrasound Doppler measurements, the authors conclude that the angular error has so little impact on longitudinal strain that correction for this error can safely be omitted. (ECHOCARDIOGRAPHY, Volume 20, October 2003) [source]

Real-time single-heartbeat fast strain-encoded imaging of right ventricular regional function: Normal versus chronic pulmonary hypertension,

MAGNETIC RESONANCE IN MEDICINE, Issue 1 2010
Monda L. Shehata
Abstract Patients with pulmonary hypertension and suspected right ventricular (RV) dysfunction often have dyspnea at rest, making reliable assessment of RV function using traditional breath-holding methods difficult to perform. Using single-heartbeat fast strain encoding (Fast-SENC) imaging, peak systolic RV circumferential and longitudinal strains were measured in 11 healthy volunteers and 11 pulmonary hypertension patients. Fast-SENC RV longitudinal strain and circumferential strain measurements were compared to conventional SENC and MR tagging, respectively. Fast-SENC circumferential and longitudinal RV shortening correlated closely with SENC measurements (r = 0.86, r = 0.90, P < 0.001 for all). Circumferential strain, by conventional tagging, showed moderate correlation with Fast-SENC in pulmonary hypertension patients only (r = 0.5, P = 0.003). A nonuniform pattern of RV circumferential shortening was depicted in both groups. Peak systolic circumferential strain was significantly reduced at the basal RV in pulmonary hypertension patients (,18.06 ± 3.3 versus ,21.9 ± 1.9, P < 0.01) compared to normal individuals, while peak systolic longitudinal strain was significantly reduced at all levels (P < 0.01 for all). Fast-SENC is a feasible and reliable technique for rapid quantification of RV regional function in a single-heartbeat acquisition. Information derived from Fast-SENC allows characterization of RV regional function in normal individuals and in pulmonary hypertension patients. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc. [source]

Impact of Temporary Interruption of Right Ventricular Pacing for Heart Block on Left Ventricular Function and Dyssynchrony

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1 2010
WEN-JING HONG M.D.
Background:The increasing data suggest an association between chronic right ventricular (RV) and left ventricular (LV) dysfunction. We sought to determine the effect of temporary interruption of long-term RV pacing on LV function and mechanical dyssynchrony in children and young adults with complete heart block. Methods:Twelve patients aged 20.0 ± 7.4 years with congenital heart block (group I) and six patients aged 22.7 ± 11.0 years with surgically acquired heart block (group II) with RV pacing were studied. The pacing rate was reduced to less than patient's intrinsic heart rate and maintained for 5 minutes. The LV ejection fraction (EF), three-dimensional systolic dyssynchrony index (SDI), two-dimensional global longitudinal strain and strain rate, and Doppler-derived isovolumic acceleration before and after interruption of RV pacing were compared. Results:The LVEF and GLS increased while QRS duration decreased after the pacing interruption in both the groups (all P < 0.05). While SDI decreased in both groups I (6.8 ± 2.3%, 3.8 ± 0.8%, P = 0.001) and II (9.2 ± 4.1%,5.0 ± 1.6%, P = 0.032), it remained higher in group II than in group I (P = 0.046) after the pacing interruption. The prevalence of LV dyssynchrony (SDI > 4.7%) decreased in group I (83%,25%, P = 0.006) but not in group II (67%,50%, P = 0.50). The %increase in LVEF correlated positively with %reduction of LV SDI (r = 0.80, P = 0.001). Conclusions:Temporary interruption of chronic RV pacing acutely improves LV dyssynchrony and systolic function in children and young adults, the magnitude of which is greater in patients with congenital than those with surgically acquired heart block. (PACE 2010; 41,48) [source]

The effect of annealing on the nonlinear viscoelastic response of isotactic polypropylene

POLYMER ENGINEERING & SCIENCE, Issue 4 2003
Aleksey D. Drozdov
Three series of tensile relaxation tests are performed on isotactic polypropylene at room temperature in the vicinity of the yield point. In the first series of experiments, injection-molded samples are used without thermal pre-treatment. In the second and third series, the specimens are annealed at 130°C for 4 and 24 hours, respectively. Constitutive equations are derived for the time-dependent response of semicrystalline polymers at isothermal loading with small strains. A polymer is treated as an equivalent temporary network of macromolecules bridged by junctions (physical cross-links, entanglements and crystalline lamellae). Under loading, junctions slide with respect to their positions in the bulk material (which reflects the viscoplastic behavior), whereas active strands separate from their junctions and dangling strands merge with the network at random times (which reflects the viscoelastic response). The network is thought of as an ensemble of meso-regions (MRs) with various activation energies for detachment of chains from temporary nodes. Adjustable parameters in the stress-strain relations are found by fitting the observations. The experimental data demonstrate that the relaxation spectrum (characterized by the distribution of MRs with various potential energies) is independent of mechanical factors, but is altered at annealing. For specimens not subjected to thermal treatment, the growth of longitudinal strain does not affect the volume fraction of active MRs and the attempt rate for detachment of chains from their junctions. For annealed samples, the concentration of active MRs increases and the attempt rate decreases with strain. These changes in the time-dependent response are attributed to broadening of the distribution of strengths of lamellae at annealing. [source]

Adaptative or maladaptative hypertrophy, different spatial distribution of myocardial contraction

CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 1 2010
Francesco Cappelli
Summary Background:, Left ventricular hypertrophy (LVH) may be an adaptative remodelling process induced by physical training, or result from pathological stimuli. We hypothesized that different LVH aetiology could lead to dissimilar spatial distribution left ventricular (LV) contraction, and compared different components of LV contraction using 2-dimensional (2-D) speckle tracking derived strain in subjects with adaptative hypertrophy (endurance athletes), maladaptative hypertrophy (hypertensive patients) and healthy controls. Method:, We enrolled 22 patients with essential hypertension, 50 endurance athletes and 24 healthy controls. All subjects underwent traditional echocardiography and 2-D strain evaluation of LV longitudinal, circumferential and radial function. LV basal and apical rotation and their net difference, defined as LV torsion, were evaluated. Results:, LV wall thicknesses, LV mass and left atrium diameter were comparable between hypertensive group and athletes. LV longitudinal strain was reduced only in hypertensive patients (P < 0·05). LV apex circumferential strain was higher in hypertensive patients than in other groups (P < 0·001), LV basal circumferential strain, although slightly increased, did not reach significant difference. Hypertensive patients showed significantly increased rotation and torsion (P < 0·001), while no differences were observed between athletes and control. Conclusion:, In patients with pathological LVH, LV longitudinal strain was reduced, while circumferential deformation and torsion were increased. No differences were observed in LV contractile function between subjects with adaptative LVH and controls. In pathological LVH, increasing torsion could be considered a compensatory mechanism to counterbalance contraction and relaxation abnormalities to maintain a normal LV output. [source]