doi: 10.1161/CIRCULATIONAHA.104.531558
(Circulation. 2005;112:3149-3156.)
© 2005 American Heart Association, Inc.
Imaging |
New Noninvasive Method for Assessment of Left Ventricular Rotation
Speckle Tracking Echocardiography
From the Department of Cardiology (T.H.-V., T.E., E.L., H.I., O.A.S.), Rikshospitalet University Hospital; the Department of Circulation and Medical Imaging (J.C., B.H.A., H.T.), Norwegian University of Science and Technology, Trondheim; and the Department of Radiology (H.-J.S.), Rikshospitalet University Hospital, Oslo, Norway; and the Department of Cardiology (B.D.R., J.A.C.L.), Johns Hopkins University, Baltimore, Md.
Correspondence to Otto A. Smiseth, Department of Cardiology, Rikshospitalet University Hospital, N-0027 Oslo, Norway. E-mail Otto.Smiseth{at}rikshospitalet.no
Received February 23, 2004; revision received August 9, 2005; accepted August 10, 2005.
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionConclusionsReferences |
|---|
Background— Left ventricular (LV) torsion is due to oppositely directed apical and basal rotation and has been proposed as a sensitive marker of LV function. In the present study, we introduce and validate speckle tracking echocardiography (STE) as a method for assessment of LV rotation and torsion.
Methods and Results— Apical and basal rotation by STE was measured from short-axis images by automatic frame-to-frame tracking of gray-scale speckle patterns. Rotation was calculated as the average angular displacement of 9 regions relative to the center of a best-fit circle through the same regions. As reference methods we used sonomicrometry in anesthetized dogs during baseline, dobutamine infusion, and apical ischemia, and magnetic resonance imaging (MRI) tagging in healthy humans. In dogs, the mean peak apical rotation was –3.7±1.2° (±SD) and –4.1±1.2°, and basal rotation was 1.9±1.5° and 2.0±1.2° by sonomicrometry and STE, respectively. Rotations by both methods increased (P<0.001) during dobutamine infusion. Apical rotation by both methods decreased during left anterior descending coronary artery occlusion (P<0.007), whereas basal rotation was unchanged. In healthy humans, apical rotation was –11.6±3.8° and –10.9±3.3°, and basal rotation was 4.8±1.7° and 4.6±1.3° by MRI tagging and STE, respectively. Torsion measurement by STE showed good correlation and agreement with sonomicrometry (r=0.94, P<0.001) and MRI (r=0.85, P<0.001).
Conclusions— The present study demonstrates that regional LV rotation and torsion can be measured accurately by STE, suggesting a new echocardiographic approach for quantification of LV systolic function.
Key Words: echocardiography • ventricles • torsion • magnetic resonance imaging • rotation
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionsReferences |
|---|
Left ventricular (LV) torsion (or twist) plays an important role with respect to LV ejection and filling.1–4 During the cardiac cycle, there is a systolic twist and an early diastolic untwist of the LV about its long axis because of oppositely directed apical and basal rotations. As viewed from the LV apex, systolic apical rotation is counterclockwise and basal rotation, clockwise. The magnitude and characteristics of this torsional deformation have been described in different clinical and experimental studies, and it is well established that LV rotation is sensitive to changes in both regional and global LV function.5–17 Therefore, assessment of LV rotation represents an interesting approach for quantifying LV function. However, so far, magnetic resonance imaging (MRI) tagging has been the only clinically available method,7,13–16,18–21 and implementation has therefore been limited by complexity and cost.
In the present study, we introduce and evaluate echocardiographic speckle tracking (STE) as a new, noninvasive method for assessment of LV rotation and torsion. Because of scattering, reflection, and interference of the ultrasound beams in myocardial tissue, speckle formations in gray-scale echocardiographic images represent tissue markers that can be tracked from frame to frame throughout the cardiac cycle. We hypothesized that STE could be an accurate and clinically applicable noninvasive method for estimating the magnitude and dynamics of LV rotation. In this study, torsion was estimated as the difference in apical and basal rotation, and the STE method was validated by comparison with sonomicrometry in a dog model and with MRI tagging in humans.
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionsReferences |
|---|
Experimental Study
Thirteen mongrel dogs of either sex and an average body weight of 23.2 kg were anesthetized with a bolus of thiopental 25 mg/kg, followed by continuous infusion of morphine (3.5 mg · kg–1 · h–1) and pentobarbital (2 mg · kg–1 · h–1), the latter reduced to half the dose after 4 hours of infusion. The animals were artificially ventilated through a cuffed endotracheal tube with room air and 20% to 50% O2. The ECG was monitored from limb leads. One femoral vein and 2 jugular arteries were cannulated. After a median sternotomy, the pericardium was split from apex to base and the edges of the pericardial incision were loosely resutured after instrumentation. Inflatable vascular occluders were placed around the proximal third of the left anterior descending coronary artery (LAD). Aortic, left atrial, and LV pressures were measured by micromanometers (MPC-500, Millar Instruments Inc). Data were digitized at 200 Hz. The dogs were placed in the supine position during recordings. The study was approved by the National Animal Experimentation Board. The laboratory animals were supplied by the Center for Comparative Medicine, Rikshospitalet University Hospital, Oslo, Norway.
Sonomicrometry
For estimation of LV torsion and apical and basal rotation, 1 sonomicrometric crystal was implanted at the tip of the apex, and 11 crystals were implanted along the LV circumference at basal (n=3), equatorial (n=4), and apical (n=4) short-axis levels (Figure 1A). Anatomy allowed only 3 crystals at the basal level. To minimize myocardial damage and to achieve reproducible and parallel planes, the crystals at each level were placed subepicardially and at distances 
20, 40, and 60 mm from the LV apex. With signals obtained from the 3D grid of crystals, the coordinates of each crystal were automatically determined in space as a function of time (200 Hz). Parallel apical, equatorial, and basal LV planes were constructed by interpolation of the corresponding crystal coordinates, and the in-plane positions were approximated by cubic Hermite interpolation (standard interpolation used in Matlab [The MathWorks Inc]). The center of rotation for each LV plane was determined as the center of a best-fit circle through the interpolated coordinates. For each plane, the angular movements of the interpolated coordinates were averaged, and LV torsion was estimated as the difference in angular movement between apical and basal planes at isochronal points. Apical and basal rotation was calculated by measuring the difference in angular movement between the equatorial level, where rotation is known to be minimal,14,15,19,22–25 and the apical and basal levels, respectively.
|
Echocardiographic Recordings and Analysis
LV short-axis recordings were obtained by conventional 2D gray-scale echocardiography (Vivid 7 scanner, GE Vingmed). Transducer frequencies (1.7 to 2.0 MHz), sampling rates (70 to 110 frames per second), and sector width (as narrow as possible) were adjusted for optimal speckle quality of the recordings. Short-axis echocardiograms were recorded in the same plane as used for sonomicrometry with the anatomic crystals as a reference. Echocardiographic recordings were done immediately before the sonomicrometric recordings and analyzed with a Matlab-based program that uses the speckle patterns in the gray-scale images. The speckle tracking method, with minimum sums of absolute differences of the B-mode pixel data,26 was used to track the position of a kernel region (a selected region of interest [ROI] with a unique speckle pattern) frame by frame throughout the cardiac cycle. To avoid drift, the tracking algorithm was applied both forward and backward, and the results were averaged. The size of the ROI was 3x5 mm, and the limit for maximum displacement velocity was set to 12 cm/s for vertical and 7 cm/s for lateral velocities. Nine ROIs were automatically superimposed on the echocardiographic image at end diastole and positioned to fit the circle-shaped LV. In our experimental study, this superimposed circle was aligned with the subepicardial LV circumference. Rarely was >1 crystal visible in the echocardiographic image. Therefore, it was not a major problem that nonphysiological speckle patterns would falsely improve tracking quality. Figure 1B shows representative recordings. The starting position of the ROIs could be adjusted manually when the tracking appeared to be poor. ROIs were excluded in regions of insufficient speckle quality because of dropouts of ultrasound data or severe reverberations. ROIs that drifted outside the wall layer being studied were also rejected. In our analyses, 93% of the ROIs remained within the LV layer of interest. Rotation was estimated as the average angular displacement of all 9 ROIs relative to the center of a best-fit circle through the same ROIs, frame by frame. Torsion was estimated as the difference between apical and basal rotation at isochronal points.
Experimental Protocol
After baseline recordings (2 to 3 hours after thoracotomy) were obtained, dobutamine was infused at a rate of 5 µg · kg–1 · min–1, and recordings were repeated. After the return of dP/dt to baseline values, the LAD was occluded for 10 minutes and recordings were obtained. Baseline data were obtained from 13 dogs, whereas dobutamine intervention was not performed in the first 4 experiments. In 5 dogs, recordings during ischemia could not be obtained because of sustained ventricular fibrillation shortly after LAD occlusion. In 6 dogs, short-axis recordings from multiple levels were obtained 5 minutes before and 5 minutes after pericardiotomy. This was done to explore the importance of an intact pericardium for LV rotation.
Clinical Study
Twenty-nine healthy volunteers (15 men and 14 women; mean age, 33±6 years) were included. The study protocol was approved by the National Committee for Medical Research Ethics of Norway. All participants gave written, informed consent.
MRI Tagging
Images were obtained with a 1.5 T scanner (Magnetom Vision Plus, Siemens). To standardize short-axis image planes between individuals, the basal cine image was defined just distal to the fibrous mitral ring, and the apical level, just proximal to the level with luminal closure at end systole. Striped tags were prescribed separately in 2 orthogonal orientations (45° and 135°) with spatial modulation of magnetization in a grid pattern with an 8-mm distance between tags and a time resolution of 35 ms. Images were acquired during 12- to 18-second breath-holds and triggered by ECG. Consistent with STE measurements, rotation by MRI tagging was calculated as the average of measurements obtained in the midendocardial and subendocardial layers. Recordings were analyzed by Harmonic Phase Imaging (HARP version 1.0, Diagnosoft Inc)27 at an experienced MRI reading center (Johns Hopkins University).
Echocardiographic Recordings and Analysis
Short-axis echocardiographic recordings were obtained with the volunteers in a supine left lateral position. The same scanner and acquisition settings were used as for the experimental recordings. Short-axis recordings at the basal level were obtained from a standard parasternal probe position, and recordings at the apical level, from a more distal anterior or anterolateral position. Short-axis images were acquired at approximately the same levels as the MRI cine images. Echocardiographic recordings were taken within 5 to 10 minutes before or after MRI examinations during breath-holds, and an effort was made to make the LV cross section as circular as possible. The quality of the speckles improved progressively from the epicardium to the endocardium, and in many cases, the subepicardial speckle quality was suboptimal. Therefore, we limited the study to assessment of rotation of the midendocardial and subendocardial layers. Criteria for adjustments or rejections of ROIs were the same as for the experimental study.
Reproducibility of the STE Method
All echocardiographic analyses were done without knowledge of the results from the reference methods. To assess interobserver variability, 6 experimental and 6 clinical echocardiographic recordings were randomly selected and then independently analyzed by 2 different observers (including selection of the cardiac cycle, placement of the ROIs, and deriving the results).
Statistical Analysis
Data are presented as mean±SD unless otherwise stated. The rotation and torsion measurements obtained by STE and reference methods were compared by a least-squares linear-regression method and by the Bland-Altman method.28 In the experimental study, we used a 1-way repeated-measures ANOVA followed by the Bonferroni correction for predefined comparisons of baseline versus dobutamine and baseline versus ischemia (SPSS version 12). Statistical differences were considered significant at P<0.05. Interobserver variability was assessed by the intraclass correlation coefficient and the Bland-Altman method.
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionsReferences |
|---|
LV Rotation and Torsion by STE Versus Sonomicrometry: Experimental Study
Figure 2 shows representative traces of LV apical and basal rotation and torsion by STE and sonomicrometry at baseline, during dobutamine infusion, and during acute LAD occlusion (apical ischemia; Table 1). By convention, the direction of rotation was referenced to apical views as clockwise (positive values) or counterclockwise (negative values). By both methods, an early systolic clockwise followed by a counterclockwise rotation during ejection was seen at the apical level, with corresponding counterclockwise-clockwise rotations at the basal level. At baseline, peak apical rotation increased with dobutamine, from –4.1±1.2° to –6.7±0.9° (P<0.001) and from –3.7±1.2° to –6.2±0.9° (P=0.001) as measured by STE and sonomicrometry, respectively. Peak basal rotation increased from 2.0±1.2° to 4.5±1.2° (P<0.001) and from 1.9±1.5° to 4.8±2.0° (P<0.001). Apical rotation decreased during LAD occlusion, to –1.8±1.3° (P<0.001) and –2.0±1.9° (P=0.007) by STE and sonomicrometry, respectively, whereas basal rotation was unchanged with either method. Correspondingly, LV torsion increased during dobutamine infusion (P<0.001) and decreased during LAD occlusion (P=0.003 by STE and P=0.055 by sonomicrometry).
|
|
Figures 3 and 4
are scatterplots, with correlation and agreement data, for peak rotation and torsion by STE and sonomicrometry. Separate regression analyzes of pooled data for apical and basal rotation by STE and sonomicrometry demonstrated good correlation (r=0.92, P<0.001, and r=0.76, P<0.001, respectively), and as shown by Bland-Altman analyses, there were no systematic differences between the methods. There was also good correlation and agreement between STE and sonomicrometry for the time to peak rotation at the apex (y=0.79x+46, r=0.58, P=0.006, and mean difference –10±49 ms) and at the base (y=0.96x+23, r=0.9, P<0.001, and mean difference –13±23 ms). For LV torsion, the results were equally good for magnitude and timing (y=0.92x–0.83, r=0.94, P<0.0001 and mean difference 0.3±1.2°, and y=0.90x+23, r=0.90, P<0.0001 and mean difference 2±26 ms, respectively).
|
|
There was no significant change in heart rate or time to peak rotation from baseline to interventions. However, there was a tendency toward increased heart rate during both ischemia and dobutamine infusion, and a reduced time to peak rotation during dobutamine infusion. Short-axis recordings from the time of crystal implantation confirmed minimal rotation at the equatorial level (–0.2±0.3°).
LV Rotation and Torsion by STE Versus MRI Tagging: Healthy Humans
Figure 5 shows representative examples of rotation and torsion by STE and MRI tagging in healthy subjects, and Table 2 summarizes the findings. Consistent with the experimental study, LV apical rotation during ejection was counterclockwise by STE and MRI, and basal rotation was clockwise. Early systolic basal rotation was counterclockwise by both methods, whereas early systolic apical clockwise rotation was confirmed only by STE.
|
|
Figure 6 displays correlation and Bland-Altman plots for STE and sonomicrometry data. The correlation and agreement between the 2 methods were good for both peak apical rotation (r=0.91, P<0.001) and peak basal rotation (r=0.67, P<0.001). There were also good correlations and agreements for time to peak apical rotation (y=0.62x+132, r=0.47, P<0.012, and mean difference –14±46 ms) and for the time to peak basal rotation (y=0.82x+62, r=0.61, P<0.001, and mean difference 0±33 ms). For the magnitude of peak torsion and time to peak torsion, correlation and agreement were also good (y=0.85x–1.6, r=0.85, P<0.001, and mean difference –1.4±2.0°, and y=0.56x+154, r=0.49, P<0.008, and mean difference –10±30 ms, respectively).
|
In our clinical study, ROIs were rejected in only 10% of the recordings (1 ROI in 6% and 2 ROIs in 4% of the recordings). In the experimental study, ROIs were rejected in 18% of the recordings (1 ROI in 10% and 2 ROIs in 8% of the recordings).
Effect of Pericardiotomy on LV Rotation and Torsion
Pericardiotomy caused no change in LV apical or basal rotation (–5.7±0.5 and –5.5±0.4° [P=NS], and 3.1±0.6 and 3.0±1.2° [P=NS], respectively). During the 2- to 3-hour period before the baseline recording, however, apical and basal rotation decreased (to –4.2±0.6, P<0.05, and 1.8±0.7°, P=NS, respectively). Furthermore, LV dP/dtmax and LV pressure, which were unaffected by pericardiotomy (2138±485 and 2134±453 mm Hg/s, P=NS, and 120±7 and 120±6 mm Hg, P=NS, respectively), decreased to 1644±319 (P=NS) and 104±5 (P=0.040), respectively, at the time of baseline recordings. Similarly, torsion was unaffected by pericardiotomy (–8.7±1.8° before versus –8.6±2.0° after) and was reduced at the time of baseline recordings (–6.0±1.5°, P<0.002).
Interobserver Variability
Measurements by STE of peak rotation by 2 independent observers showed a mean difference between the 2 analyses of 0.4±1.6°. The intraclass correlation coefficient between the 2 observers was 0.99. The typical time spent for data analysis was <1 minute.
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionsReferences |
|---|
Echocardiography is one of the cornerstones for diagnosing and monitoring cardiac diseases. However, angle-independent assessment of LV deformation and rotation has only been possible by MRI tagging. The present study demonstrates that STE can measure LV torsional deformation noninvasively by automated tracking of speckles from apical and basal short-axis recordings. The validity of our approach was tested with sonomicrometry as a reference method in an animal model and MRI tagging in humans. With sonomicrometry, the implanted myocardial crystals served as anatomic landmarks that ensured that the LV cross-sectional planes studied by the 2 methods were the same, and measurements could be performed only a few seconds apart. Furthermore, in the animal model, comparison between the methods could be completed under a wide range of experimental settings known to alter LV rotation. The STE method showed dynamics, magnitudes, and timing of peak basal and apical rotation and torsion that were closely related to measurements by sonomicrometry. The same relation was found when STE was compared with MRI in healthy volunteers.
Apical Rotation
In the present study, counterclockwise rotation during LV ejection was demonstrated at the apical level in healthy individuals and was found in the dog model. During dobutamine infusion, there was an increase in apical rotation and a tendency toward a decrease in the time to peak rotation, whereas during LAD occlusion, apical rotation was reduced. These changes in apical rotation by dobutamine and apical ischemia are concordant with the findings from previous studies that have used other methods.2,8,10,11,29
Although systolic apical rotation was predominantly counterclockwise, there was a small, clockwise rotation during isovolumic contraction. The oppositely directed rotation was demonstrated by both sonomicrometry and STE but not by MRI (see Figures 3 and 5
). This phenomenon has been described previously and might be attributed to earlier activation of subendocardial fibers (right-handed helix) than subepicardial fibers.1,6,30,31 The reason why this motion was not recognized by MRI tagging is probably the relatively low temporal resolution of the method (35 ms).
Basal Rotation
Consistent with previous studies, 14–16,19–21,23–25 LV rotation at the base was predominantly clockwise. During early systole, however, there was a counterclockwise rotation that gradually changed into a more substantial clockwise rotation during ejection. Dobutamine infusion caused a significant increase in basal clockwise rotation, with no change in the time to peak rotation. To our knowledge, no previous studies exist of basal rotation during dobutamine infusion. Apical ischemia caused no significant change in basal rotation,14 reflecting the fact that there was no impairment of LV function between equator and base.
Some studies have indicated that basal LV rotation is minimal.3,12 However, in patients with aortic stenosis, a reduced magnitude of basal rotation compared with normal hearts has been observed.20 Furthermore, in patients with chronic heart failure, 6 months of treatment was associated with an increase in basal rotation, whereas apical rotation was unchanged,16 indicating that measurement of basal rotation may be clinically relevant. However, compared with the reference methods, assessment of rotation by STE was less accurate for the basal level than for the apical level. Therefore, deviations in basal rotation could be difficult to assess by STE, and larger clinical studies will need to be performed to answer this question.
Comparison With Previous Studies
The magnitudes of LV apical and basal rotation and torsion, as reported in previous experimental and clinical studies, differ substantially,2–6,8,9,12–18,20,22–25,29,32–39 and a number of factors may explain this variance. As demonstrated by Henson et al,22 apparent differences in torsion between mice and humans are due to the different sizes of their ventricles. When systolic torsion angle was normalized for LV length, torsion was essentially similar in the 2 species. Furthermore, because torsion angle is a nonlinear function of ventricular length, its magnitude depends critically on the measurement level relative to the LV base or other reference point. The relatively high values of apical rotation measured by Gibbons Kroeker et al3 are most likely explained by their measurement technique, which recorded rotation at the distal part of the LV apex. Another factor that may explain some of the variance in torsion magnitude in different studies is the existence of a marked transmural gradient, with subendocardial values almost twice those of subepicardial values.18 In the dog model, we measured subepicardial rotation, and during baseline conditions, torsion was 6°. These values are in the same range as reported by Buchalter et al,8 who measured both subepicardial and subendocardial torsion in anesthetized dogs by MRI tagging. Furthermore, the hemodynamic and contractile status of the heart in different animal models may vary and give rise to differences in torsion. A significant reduction in rotation at the apical level and a trend toward a reduction at the base was found at the time of baseline recordings. This was associated with reductions in LV pressure and LV dP/dtmax, indicating that there was some reduction in LV systolic function. Most likely the decrease in rotation reflects impairment of LV function owing to the extensive surgical instrumentation.
Limitations
Several important factors may influence the accuracy of STE. The quality of the recordings must be high to achieve correct tracking, and it requires proper adjustment of frame rate, probe frequency, and focus. In the present study, tracking quality was evaluated visually, and ROIs of poor tracking were either manually moved to areas of better speckle quality or deleted. Because rotational displacement is relatively homogenously distributed around the LV circumference in healthy myocardium, deletion of 1 or a maximum of 2 ROIs will have a minimal effect on average rotation.8,18,33
A fundamental problem with STE in LV short-axis images is that longitudinal motion of the LV causes the myocardium to move in and out of the image plane. As a consequence, speckles generated from the ultrasound beam (2 to 3 mm of thickness) will represent the myocardium from different cross-sectional levels during the cardiac cycle. This problem is most pronounced at the LV base, where the longitudinal displacement, according to our results, was 4 mm from end diastole to end systole, whereas the LV apex was essentially stationary. In our study, the relation between STE and the reference methods was best at the apical level, probably because of the aforementioned phenomenon.
A limitation in the clinical study was that speckle quality in some cases was suboptimal in the subepicardial layer of the LV. Therefore, for validation against MRI, we compared measurements from the middle and inner wall layers. Hopefully, technical developments in ultrasound technology will resolve this problem. In the dog study, we had direct access to the heart via sternotomy, and by using ultrasound gel as a standoff, we obtained satisfactory tracking quality in all layers of the LV wall.
One limitation of clinical routine use of STE is the selection of reproducible anatomic landmarks for measuring apical rotation. One approach was to move the cross-sectional image plane as far distally as possible. Another approach could be to measure at the most distal level that does not have luminal closure during systole. At the basal level, reproducible image planes were easier to obtain with the fibrous mitral ring for orientation. Selection of imaging plane is a challenge, and clinical testing of STE in patients is needed to determine whether reproducible measurements can be obtained from ventricles that may change in size and geometry over time.
In contrast to STE, which provides a measure relative to a stationary reference point outside the heart (the echocardiographic transducer), sonomicrometry provides no direct measure of rotation. Because apical and basal rotations are in opposite directions, somewhere between them there exists a level where rotation changes from one direction to the other. A number of studies in dogs, mice, and humans have confirmed that the short-axis level approximately one third from the base to apex (LV equator) shows minimal rotation.14,15,19,22–25 In our study, we measured rotation at the equatorial level by the time of crystal implantation, and the results confirmed minimal rotation (–0.2±2.3°). Taking into account the good relation between STE and sonomicrometry, this finding indicates that our methodological approach was adequate. Furthermore, for strict methodological comparison of STE with sonomicrometry, assessment of LV torsion was sufficient, and the correlation and agreement between torsion by the 2 methods were very good.
|
Conclusions |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionsReferences |
|---|
This study demonstrates that the magnitude, timing, and dynamics of regional LV rotation and torsion can be measured accurately by STE. When MRI and sonomicrometry were used as reference methods, STE showed good correlation and agreement, suggesting that STE has the potential to become a fast and accurate noninvasive clinical tool.
|
Acknowledgments |
|---|
Thomas Helle-Valle and Erik Lyseggen were recipients of clinical research fellowships from the Norwegian Council of Cardiovascular Diseases. Jonas Crosby and Brage H. Amundsen received clinical research fellowships from the Norwegian Research Council. We thank Drs Trond Vartdal, Eirik Pettersen, and Anders Opdahl for beneficial collaboration in the laboratory, and MSc Eldrid Winther-Larssen and engineer Roger Odegaard for technical assistance.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionsReferences |
|---|
1. McDonald IG. The shape and movements of the human left ventricle during systole: a study by cineangiography and by cineradiography of epicardial markers. Am J Cardiol. 1970; 26: 221–230.[CrossRef][Medline] [Order article via Infotrieve]
2. Rademakers FE, Buchalter MB, Rogers WJ, Zerhouni EA, Weisfeldt ML, Weiss JL, Shapiro EP. Dissociation between left ventricular untwisting and filling: accentuation by catecholamines. Circulation. 1992; 85: 1572–1581.
3. Gibbons Kroeker CA, Ter Keurs HE, Knudtson ML, Tyberg JV, Beyar R. An optical device to measure the dynamics of apex rotation of the left ventricle. Am J Physiol Heart Circ Physiol. 1993; 265: H1444–H1449.
4. Moon MR, Ingels NB Jr, Daughters GT, Stinson EB, Hansen DE, Miller DC. Alterations in left ventricular twist mechanics with inotropic stimulation and volume loading in human subjects. Circulation. 1994; 89: 142–150.
5. Hansen DE, Daughters GT, Alderman EL, Ingels NB, Stinson EB, Miller DC. Effect of volume loading, pressure loading, and inotropic stimulation on left ventricular torsion in humans. Circulation. 1991; 83: 1315–1326.
6. Yun KL, Niczyporuk MA, Daughters GT, Ingels NB Jr, Stinson EB, Alderman EL, Hansen DE, Miller DC. Alterations in left ventricular diastolic twist mechanics during acute human cardiac allograft rejection. Circulation. 1991; 83: 962–973.
7. Maier SE, Fischer SE, McKinnon GC, Hess OM, Krayenbuehl HP, Boesiger P. Evaluation of left ventricular segmental wall motion in hypertrophic cardiomyopathy with myocardial tagging. Circulation. 1992; 86: 1919–1928.
8. Buchalter MB, Rademakers FE, Weiss JL, Rogers WJ, Weisfeldt ML, Shapiro EP. Rotational deformation of the canine left ventricle measured by magnetic resonance tagging: effects of catecholamines, ischaemia, and pacing. Cardiovasc Res. 1994; 28: 629–635.
9. DeAnda A Jr, Komeda M, Nikolic SD, Daughters GT II, Ingels NB, Miller DC. Left ventricular function, twist, and recoil after mitral valve replacement. Circulation. 1995; 92: 458–466.
10. Gibbons Kroeker CA, Tyberg JV, Beyar R. Effects of load manipulations, heart rate, and contractility on left ventricular apical rotation: an experimental study in anesthetized dogs. Circulation. 1995; 92: 130–141.
11. Gibbons Kroeker CA, Tyberg JV, Beyar R. Effects of ischemia on left ventricular apex rotation: an experimental study in anesthetized dogs. Circulation. 1995; 92: 3539–3548.
12. Knudtson ML, Galbraith PD, Hildebrand KL, Tyberg JV, Beyar R. Dynamics of left ventricular apex rotation during angioplasty: a sensitive index of ischemic dysfunction. Circulation. 1997; 96: 801–808.
13. Stuber M, Scheidegger MB, Fischer SE, Nagel E, Steinemann F, Hess OM, Boesiger P. Alterations in the local myocardial motion pattern in patients suffering from pressure overload due to aortic stenosis. Circulation. 1999; 100: 361–368.
14. Nagel E, Stuber M, Lakatos M, Scheidegger MB, Boesiger P, Hess OM. Cardiac rotation and relaxation after anterolateral myocardial infarction. Coron Artery Dis. 2000; 11: 261–267.[CrossRef][Medline] [Order article via Infotrieve]
15. Sandstede JJW, Johnson T, Harre K, Beer M, Hofmann S, Pabst T, Kenn W, Voelker W, Neubauer S, Hahn D. Cardiac systolic rotation and contraction before and after valve replacement for aortic stenosis: a myocardial tagging study using MR imaging. Am J Roentgenol. 2002; 178: 953–958.
16. Fuchs E, Muller MF, Oswald H, Thony H, Mohacsi P, Hess OM. Cardiac rotation and relaxation in patients with chronic heart failure. Eur J Heart Failure. 2004; 6: 715–722.
17. Tibayan FA, Rodriguez F, Langer F, Zasio MK, Bailey L, Liang D, Daughters GT, Ingels NB Jr, Miller DC. Alterations in left ventricular torsion and diastolic recoil after myocardial infarction with and without chronic ischemic mitral regurgitation. Circulation. 2004; 110 (suppl II): II-109–II-114.Abstract.[Medline] [Order article via Infotrieve]
18. Buchalter MB, Weiss JL, Rogers WJ, Zerhouni EA, Weisfeldt ML, Beyar R, Shapiro EP. Noninvasive quantification of left ventricular rotational deformation in normal humans using magnetic resonance imaging myocardial tagging. Circulation. 1990; 81: 1236–1244.
19. Fogel MA, Weinberg PM, Hubbard A, Haselgrove J. Diastolic biomechanics in normal infants utilizing MRI tissue tagging. Circulation. 2000; 102: 218–224.
20. Nagel E, Stuber M, Burkhard B, Fischer SE, Scheidegger MB, Boesiger P, Hess OM. Cardiac rotation and relaxation in patients with aortic valve stenosis. Eur Heart J. 2000; 21: 582–589.
21. Setser RM, Kasper JM, Lieber ML, Starling RC, McCarthy PM, White RD. Persistent abnormal left ventricular systolic torsion in dilated cardiomyopathy after partial left ventriculectomy. J Thorac Cardiovasc Surg. 2003; 126: 48–55.
22. Henson RE, Song SK, Pastorek JS, Ackerman JJH, Lorenz CH. Left ventricular torsion is equal in mice and humans. Am J Physiol Heart Circ Physiol. 2000; 278: H1117–H1123.
23. Lorenz CH, Pastorek JS, Bundy JM. Delineation of normal human left ventricular twist throughout systole by tagged cine magnetic resonance imaging. J Cardiovasc Magn Reson. 2000; 2: 97–108.[Medline] [Order article via Infotrieve]
24. Moore CC, Lugo-Olivieri CH, McVeigh ER, Zerhouni EA. Three-dimensional systolic strain patterns in the normal human left ventricle: characterization with tagged MR imaging. Radiology. 2000; 214: 453–466.
25. Nichols K, Kamran M, Cooke CD, Faber TL, Garcia EV, Bergmann SR, Depuey EG. Feasibility of detecting cardiac torsion in myocardial perfusion gated SPECT data. J Nucl Cardiol. 2003; 9: 500–507.[CrossRef]
26. Bohs LN, Trahey GE. A novel method for angle independent ultrasonic imaging of blood flow and tissue motion. IEEE Trans Biomed Eng. 1991; 38: 280–286.[CrossRef][Medline] [Order article via Infotrieve]
27. Garot J, Bluemke DA, Osman NF, Rochitte CE, McVeigh ER, Zerhouni EA, Prince JL, Lima JAC. Fast determination of regional myocardial strain fields from tagged cardiac images using harmonic phase MRI. Circulation. 2000; 101: 981–988.
28. Martin Bland J, Altman D. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet. 1986; 327: 307–310.[CrossRef]
29. Dong SJ, Hees PS, Huang WM, Buffer SA Jr, Weiss JL, Shapiro EP. Independent effects of preload, afterload, and contractility on left ventricular torsion. Am J Physiol Heart Circ Physiol. 1999; 277: H1053–H1060.
30. Durrer D, Van Dam RT, Freud GE, Janse MJ, Meijler FL, Arzbaecher RC. Total excitation of isolated human heart. Circulation. 1970; 41: 899–912.
31. Azhari H, Buchalter M, Sideman S, Shapiro E, Beyar R. A conical model to describe the nonuniformity of the left-ventricular twisting motion. Ann Biomed Eng. 1992; 20: 149–165.[CrossRef][Medline] [Order article via Infotrieve]
32. Mirro MJ, Rogers EW, Weyman AE, Feigenbaum H. Angular displacement of the papillary muscles during the cardiac cycle. Circulation. 1979; 60: 327–333.
33. Hansen DE, Daughters GT, Alderman EL, Ingels NB Jr, Miller DC. Torsional deformation of the left ventricular midwall in human hearts with intramyocardial markers: regional heterogeneity and sensitivity to the inotropic effects of abrupt rate changes. Circ Res. 1988; 62: 941–952.
34. MacGowan GA, Burkhoff D, Rogers WJ, Salvador D, Azhari H, Hees PS, Zweier JL, Halperin HR, Siu CO, Lima JAC. Effects of afterload on regional left ventricular torsion. Cardiovasc Res. 1996; 31: 917–925.[CrossRef][Medline] [Order article via Infotrieve]
35. Rothfeld JM, LeWinter MM, Tischler MD. Left ventricular systolic torsion and early diastolic filling by echocardiography in normal humans. Am J Cardiol. 1998; 81: 1465–1469.[CrossRef][Medline] [Order article via Infotrieve]
36. Stuber M, Nagel E, Fischer SE, Spiegel MA, Scheidegger MB, Boesiger P. Quantification of the local heartwall motion by magnetic resonance myocardial tagging. Comput Med Imaging Graph. 1998; 22: 217–228.[CrossRef][Medline] [Order article via Infotrieve]
37. Bell SP, Nyland L, Tischler MD, McNabb M, Granzier H, LeWinter MM. Alterations in the determinants of diastolic suction during pacing tachycardia. Circ Res. 2000; 87: 235–240.
38. Tibayan FA, Yun KL, Fann JI, Lai DT, Timek TA, Daughters GT, Ingels NB, Miller DC. Torsion dynamics in the evolution from acute to chronic mitral regurgitation [erratum appears in J Heart Valve Dis. 2002;11:477]. J Heart Valve Dis. 2002; 11: 39–46.[Medline] [Order article via Infotrieve]
39. Sorger JM, Wyman BT, Faris OP, Hunter WC, McVeigh ER. Torsion of the left ventricle during pacing with MRI tagging. J Cardiovasc Magn Reson. 2003; 5: 521–530.[CrossRef][Medline] [Order article via Infotrieve]
This article has been cited by other articles:
 |
|
 |
|
  E. Donal, C. Bergerot, H. Thibault, L. Ernande, J. Loufoua, L. Augeul, M. Ovize, and G. Derumeaux Influence of afterload on left ventricular radial and longitudinal systolic functions: a two-dimensional strain imaging study Eur J Echocardiogr, December 1, 2009; 10(8): 914 - 921. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. A. Popescu, C. C. Beladan, A. Calin, D. Muraru, D. Deleanu, M. Rosca, and C. Ginghina Left ventricular remodelling and torsional dynamics in dilated cardiomyopathy: reversed apical rotation as a marker of disease severity Eur J Heart Fail, October 1, 2009; 11(10): 945 - 951. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Bertini, N. A. Marsan, V. Delgado, R. J. van Bommel, G. Nucifora, C. J. W. Borleffs, G. Boriani, M. Biffi, E. R. Holman, E. E. van der Wall, et al. Effects of cardiac resynchronization therapy on left ventricular twist. J. Am. Coll. Cardiol., September 29, 2009; 54(14): 1317 - 1325. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. N. Shivu, K. Abozguia, T. T. Phan, I. Ahmed, R. Weaver, P. Narendran, M. Stevens, and M. Frenneaux Increased Left Ventricular Torsion in Uncomplicated Type 1 Diabetic Patients: The role of coronary microvascular function Diabetes Care, September 1, 2009; 32(9): 1710 - 1712. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H.-J. Nesser, V. Mor-Avi, W. Gorissen, L. Weinert, R. Steringer-Mascherbauer, J. Niel, L. Sugeng, and R. M. Lang Quantification of left ventricular volumes using three-dimensional echocardiographic speckle tracking: comparison with MRI Eur. Heart J., July 1, 2009; 30(13): 1565 - 1573. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. Ferferieva, P. Claus, K. Vermeulen, C. Missant, M. Szulik, F. Rademakers, and J. D'hooge Echocardiographic assessment of left ventricular untwist rate: comparison of tissue Doppler and speckle tracking methodologies Eur J Echocardiogr, July 1, 2009; 10(5): 683 - 690. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. M. van Dalen, O. I.I. Soliman, W. B. Vletter, F. Kauer, H. B. van der Zwaan, F. J. ten Cate, and M. L. Geleijnse Feasibility and reproducibility of left ventricular rotation parameters measured by speckle tracking echocardiography Eur J Echocardiogr, July 1, 2009; 10(5): 669 - 676. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Helle-Valle, E. W. Remme, E. Lyseggen, E. Pettersen, T. Vartdal, A. Opdahl, H.-J. Smith, N. F. Osman, H. Ihlen, T. Edvardsen, et al. Clinical assessment of left ventricular rotation and strain: a novel approach for quantification of function in infarcted myocardium and its border zones Am J Physiol Heart Circ Physiol, July 1, 2009; 297(1): H257 - H267. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. T. Tan, F. Wenzelburger, E. Lee, G. Heatlie, F. Leyva, K. Patel, M. Frenneaux, and J. E. Sanderson The pathophysiology of heart failure with normal ejection fraction exercise echocardiography reveals complex abnormalities of both systolic and diastolic ventricular function involving torsion, untwist, and longitudinal motion. J. Am. Coll. Cardiol., June 30, 2009; 54(1): 36 - 46. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. T. Burns, A. La Gerche, D. L. Prior, and A. I. MacIsaac Left Ventricular Untwisting Is an Important Determinant of Early Diastolic Function J. Am. Coll. Cardiol. Img., June 1, 2009; 2(6): 709 - 716. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Opdahl, E. W. Remme, T. Helle-Valle, E. Lyseggen, T. Vartdal, E. Pettersen, T. Edvardsen, and O. A. Smiseth Determinants of Left Ventricular Early-Diastolic Lengthening Velocity: Independent Contributions From Left Ventricular Relaxation, Restoring Forces, and Lengthening Load Circulation, May 19, 2009; 119(19): 2578 - 2586. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. K. Russel, M. J.W. Gotte, J. G. Bronzwaer, P. Knaapen, W. J. Paulus, and A. C. van Rossum Left ventricular torsion an expanding role in the analysis of myocardial dysfunction. J. Am. Coll. Cardiol. Img., May 1, 2009; 2(5): 648 - 655. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. Delgado, L. F. Tops, S. A. Trines, K. Zeppenfeld, N. Ajmone Marsan, M. Bertini, E. R. Holman, M. J. Schalij, and J. J. Bax Acute Effects of Right Ventricular Apical Pacing on Left Ventricular Synchrony and Mechanics Circ Arrhythm Electrophysiol, April 1, 2009; 2(2): 135 - 145. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B M van Dalen, F Kauer, O I I Soliman, W B Vletter, M Michels, F J t. Cate, and M L Geleijnse Influence of the pattern of hypertrophy on left ventricular twist in hypertrophic cardiomyopathy Heart, April 1, 2009; 95(8): 657 - 661. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Wang and S. F. Nagueh Current Perspectives on Cardiac Function in Patients With Diastolic Heart Failure Circulation, March 3, 2009; 119(8): 1146 - 1157. [Full Text] [PDF]
|
|
|
|
|
|
C. Goffinet, F. Chenot, A. Robert, A.-C. Pouleur, J.-B. l. P. de Waroux, D. Vancrayenest, O. Gerard, A. Pasquet, B. L. Gerber, and J.-L. Vanoverschelde Assessment of subendocardial vs. subepicardial left ventricular rotation and twist using two-dimensional speckle tracking echocardiography: comparison with tagged cardiac magnetic resonance Eur. Heart J., March 1, 2009; 30(5): 608 - 617. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. B. Ennis, T. C. Nguyen, A. Itoh, W. Bothe, D. H. Liang, N. B. Ingels, and D. C. Miller Reduced Systolic Torsion in Chronic "Pure" Mitral Regurgitation Circ Cardiovasc Imaging, March 1, 2009; 2(2): 85 - 92. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W.-J. Kim, B. H. Lee, Y. J. Kim, J. H. Kang, Y. J. Jung, J.-M. Song, D.-H. Kang, and J.-K. Song Apical Rotation Assessed by Speckle-Tracking Echocardiography as an Index of Global Left Ventricular Contractility Circ Cardiovasc Imaging, March 1, 2009; 2(2): 123 - 131. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. H. Bijnens, M. Cikes, P. Claus, and G. R. Sutherland Velocity and deformation imaging for the assessment of myocardial dysfunction Eur J Echocardiogr, March 1, 2009; 10(2): 216 - 226. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. F. Nagueh, C. P. Appleton, T. C. Gillebert, P. N. Marino, J. K. Oh, O. A. Smiseth, A. D. Waggoner, F. A. Flachskampf, P. A. Pellikka, and A. Evangelisa Recommendations for the Evaluation of Left Ventricular Diastolic Function by Echocardiography Eur J Echocardiogr, March 1, 2009; 10(2): 165 - 193. [Full Text] [PDF]
|
|
|
|
|
|
T. P. Abraham and H.-Y. Liang Stress echocardiography diastole to the rescue. J. Am. Coll. Cardiol., February 24, 2009; 53(8): 706 - 708. [Full Text] [PDF]
|
|
|
|
 |
|
 B. T. Esch and D. E. R. Warburton Left ventricular torsion and recoil: implications for exercise performance and cardiovascular disease J Appl Physiol, February 1, 2009; 106(2): 362 - 369. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M Saito, H Okayama, K Nishimura, A Ogimoto, T Ohtsuka, K Inoue, G Hiasa, T Sumimoto, J Funada, Y Shigematsu, et al. Determinants of left ventricular untwisting behaviour in patients with dilated cardiomyopathy: analysis by two-dimensional speckle tracking Heart, February 1, 2009; 95(4): 290 - 296. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
U. Gustafsson, P. Lindqvist, S. Morner, and A. Waldenstrom Assessment of regional rotation patterns improves the understanding of the systolic and diastolic left ventricular function: an echocardiographic speckle-tracking study in healthy individuals Eur J Echocardiogr, January 1, 2009; 10(1): 56 - 61. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Nishikage, H. Nakai, V. Mor-Avi, R. M. Lang, I. S. Salgo, S. H. Settlemier, S. Husson, and M. Takeuchi Quantitative assessment of left ventricular volume and ejection fraction using two-dimensional speckle tracking echocardiography Eur J Echocardiogr, January 1, 2009; 10(1): 82 - 88. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. S. Halvorsen, A. Espinoza, L. A. Fleischer, O. J. Elle, L. Hoff, R. Lundblad, H. Skulstad, T. Edvardsen, H. Ihlen, and E. Fosse Feasibility of a three-axis epicardial accelerometer in detecting myocardial ischemia in cardiac surgical patients. J. Thorac. Cardiovasc. Surg., December 1, 2008; 136(6): 1496 - 1502. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Marcucci, R. Lauer, and A. Mahajan New Echocardiographic Techniques for Evaluating Left Ventricular Myocardial Function Seminars in Cardiothoracic and Vascular Anesthesia, December 1, 2008; 12(4): 228 - 247. [Abstract] [PDF]
|
|
|
|
|
|
L. C. Afonso, J. Bernal, J. J. Bax, and T. P. Abraham Echocardiography in hypertrophic cardiomyopathy: the role of conventional and emerging technologies. J. Am. Coll. Cardiol. Img., November 1, 2008; 1(6): 787 - 800. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O. Gjesdal, T. Helle-Valle, E. Hopp, K. Lunde, T. Vartdal, S. Aakhus, H.-J. Smith, H. Ihlen, and T. Edvardsen Noninvasive Separation of Large, Medium, and Small Myocardial Infarcts in Survivors of Reperfused ST-Elevation Myocardial Infarction: A Comprehensive Tissue Doppler and Speckle-Tracking Echocardiography Study Circ Cardiovasc Imaging, November 1, 2008; 1(3): 189 - 196. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. M. van Dalen, K. Caliskan, O. I.I. Soliman, A. Nemes, W. B. Vletter, F. J. ten Cate, and M. L. Geleijnse Left ventricular solid body rotation in non-compaction cardiomyopathy: A potential new objective and quantitative functional diagnostic criterion? Eur J Heart Fail, November 1, 2008; 10(11): 1088 - 1093. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Perry, C. G. De Pasquale, D. P. Chew, and M. X. Joseph Assessment of early diastolic left ventricular function by two-dimensional echocardiographic speckle tracking Eur J Echocardiogr, November 1, 2008; 9(6): 791 - 795. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Q Zhang, J W-H Fung, G W K Yip, J Y-S Chan, A P-W Lee, Y-Y Lam, L-W Wu, E B Wu, and C-M Yu Improvement of left ventricular myocardial short-axis, but not long-axis function or torsion after cardiac resynchronisation therapy: an assessment by two-dimensional speckle tracking Heart, November 1, 2008; 94(11): 1464 - 1471. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Nottin, G. Doucende, I. Schuster-Beck, M. Dauzat, and P. Obert Alteration in left ventricular normal and shear strains evaluated by 2D-strain echocardiography in the athlete's heart J. Physiol., October 1, 2008; 586(19): 4721 - 4733. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. M. van Dalen, O. I. I. Soliman, W. B. Vletter, F. J. ten Cate, and M. L. Geleijnse Age-related changes in the biomechanics of left ventricular twist measured by speckle tracking echocardiography Am J Physiol Heart Circ Physiol, October 1, 2008; 295(4): H1705 - H1711. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A T Burns, I G McDonald, J D Thomas, A MacIsaac, and D Prior Doin' the twist: new tools for an old concept of myocardial function Heart, August 1, 2008; 94(8): 978 - 983. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N R Van de Veire, J De Sutter, J J Bax, and J R T C Roelandt Technological advances in tissue Doppler imaging echocardiography Heart, August 1, 2008; 94(8): 1065 - 1074. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. A. Aase, H. Torp, and A. Stoylen Aortic valve closure: relation to tissue velocities by Doppler and speckle tracking in normal subjects Eur J Echocardiogr, July 1, 2008; 9(4): 555 - 559. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Wang, D. S. Khoury, Y. Yue, G. Torre-Amione, and S. F. Nagueh Preserved left ventricular twist and circumferential deformation, but depressed longitudinal and radial deformation in patients with diastolic heart failure Eur. Heart J., May 2, 2008; 29(10): 1283 - 1289. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. C. Gillebert and N. R. Van de Veire About left ventricular torsion, sex differences, shear strain, and diastolic heart failure Eur. Heart J., May 2, 2008; 29(10): 1215 - 1217. [Full Text] [PDF]
|
|
|
|
|
|
P. P. Sengupta, A. J. Tajik, K. Chandrasekaran, and B. K. Khandheria Twist mechanics of the left ventricle principles and application. J. Am. Coll. Cardiol. Img., May 1, 2008; 1(3): 366 - 376. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A N Borg, J L Harrison, R A Argyle, and S G Ray Left ventricular torsion in primary chronic mitral regurgitation Heart, May 1, 2008; 94(5): 597 - 603. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Becker, A. Lenzen, C. Ocklenburg, K. Stempel, H. Kuhl, M. Neizel, M. Katoh, R. Kramann, J. Wildberger, M. Kelm, et al. Myocardial Deformation Imaging Based on Ultrasonic Pixel Tracking to Identify Reversible Myocardial Dysfunction J. Am. Coll. Cardiol., April 15, 2008; 51(15): 1473 - 1481. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. A. Dorfman, B. D. Rosen, M. A. Perhonen, T. Tillery, R. McColl, R. M. Peshock, and B. D. Levine Diastolic suction is impaired by bed rest: MRI tagging studies of diastolic untwisting J Appl Physiol, April 1, 2008; 104(4): 1037 - 1044. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Z B Popovic, R A Grimm, A Ahmad, D Agler, M Favia, G Dan, P Lim, F Casas, N L Greenberg, and J D Thomas Longitudinal rotation: an unrecognised motion pattern in patients with dilated cardiomyopathy Heart, March 1, 2008; 94(3): e11 - e11. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Lindqvist, A. Calcutteea, and M. Henein Echocardiography in the assessment of right heart function Eur J Echocardiogr, March 1, 2008; 9(2): 225 - 234. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. P. Abraham and A. C. Pinheiro Speckle-Derived Strain: A Better Tool for Quantification of Stress Echocardiography? J. Am. Coll. Cardiol., January 15, 2008; 51(2): 158 - 160. [Full Text] [PDF]
|
|
|
|
|
|
P. P. Sengupta, V. K. Krishnamoorthy, W. P. Abhayaratna, J. Korinek, M. Belohlavek, T. M. Sundt III, K. Chandrasekaran, F. Mookadam, J. B. Seward, A. J. Tajik, et al. Disparate patterns of left ventricular mechanics differentiate constrictive pericarditis from restrictive cardiomyopathy. J. Am. Coll. Cardiol. Img., January 1, 2008; 1(1): 29 - 38. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. J. Penny, J. P. Mynard, and J. J. Smolich Aortic wave intensity analysis of ventricular-vascular interaction during incremental dobutamine infusion in adult sheep Am J Physiol Heart Circ Physiol, January 1, 2008; 294(1): H481 - H489. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Rakowski and S. Carasso Quantifying Diastolic Function in Hypertrophic Cardiomyopathy: The Ongoing Search for the Holy Grail Circulation, December 4, 2007; 116(23): 2662 - 2665. [Full Text] [PDF]
|
|
|
|
|
|
J. Wang, D. S. Khoury, Y. Yue, G. Torre-Amione, and S. F. Nagueh Left Ventricular Untwisting Rate by Speckle Tracking Echocardiography Circulation, November 27, 2007; 116(22): 2580 - 2586. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Takeuchi, W. B. Borden, H. Nakai, T. Nishikage, M. Kokumai, T. Nagakura, S. Otani, and R. M Lang Reduced and delayed untwisting of the left ventricle in patients with hypertension and left ventricular hypertrophy: a study using two-dimensional speckle tracking imaging Eur. Heart J., November 2, 2007; 28(22): 2756 - 2762. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. N. Kirkpatrick, M. A. Vannan, J. Narula, and R. M. Lang Echocardiography in Heart Failure: Applications, Utility, and New Horizons J. Am. Coll. Cardiol., July 31, 2007; 50(5): 381 - 396. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Pettersen, T. Helle-Valle, T. Edvardsen, H. Lindberg, H.-J. Smith, B. Smevik, O. A. Smiseth, and K. Andersen Contraction Pattern of the Systemic Right Ventricle: Shift From Longitudinal to Circumferential Shortening and Absent Global Ventricular Torsion J. Am. Coll. Cardiol., June 26, 2007; 49(25): 2450 - 2456. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Z. B. Popovic, C. Benejam, J. Bian, N. Mal, J. Drinko, K. Lee, F. Forudi, R. Reeg, N. L. Greenberg, J. D. Thomas, et al. Speckle-tracking echocardiography correctly identifies segmental left ventricular dysfunction induced by scarring in a rat model of myocardial infarction Am J Physiol Heart Circ Physiol, June 1, 2007; 292(6): H2809 - H2816. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. E. Weyman The Year in Echocardiography J. Am. Coll. Cardiol., March 20, 2007; 49(11): 1212 - 1219. [Full Text] [PDF]
|
|
|
|
|
|
J. D. Thomas and Z. B. Popovic Assessment of Left Ventricular Function by Cardiac Ultrasound J. Am. Coll. Cardiol., November 21, 2006; 48(10): 2012 - 2025. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Foster and K. E. Lease New Untwist on Diastole: What Goes Around Comes Back Circulation, May 30, 2006; 113(21): 2477 - 2479. [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||