Echocardiographic Strain Imaging Research Articles

Quantifying the Role of Regional Dyssynchrony on Global Left Ventricular Performance

We hypothesize that left ventricular (LV) segmental dyssynchrony, quantified by paradoxical systolic wall thinning, determines changes in global LV performance in a model of canine right ventricular (RV) pacing-induced dyssynchrony and the response to cardiac resynchronization therapy (CRT). Quantification of LV dyssynchrony is important to assess the impact of CRT. Seven pentobarbital-anesthetized open-chest dogs had LV pressure-volume relations and mid-LV short-axis echocardiographic speckle tracking radial strain imaging during right atrial (RA) pacing, RV pacing to simulate left bundle branch block, and CRT using RV pacing plus either LV free-wall (CRTfw) and apical (CRTa) pacing. The area under the segmental LV time-radial strain positive and negative curves defined global thickening and thinning, respectively. Dyssynchrony was defined as the maximum time difference between earliest and latest peak segmental positive strain among 6 radial sites. RA pacing had minimal dyssynchrony (58 + or - 40 ms). RV pacing induced both dyssynchrony (213 + or - 67 ms, p < 0.05) and reduced LV stroke work (SW) (67 + or - 51 mJ, p < 0.05). CRTfw and CRTa decreased dyssynchrony (116 + or - 47 ms and 50 + or - 34 ms, respectively, p < 0.05 vs. RV pacing), but only CRTa restored LV SW to RA pacing levels. RV pacing decreased global thickening (129 + or - 87%.ms) compared with RA pacing (258 + or - 133%.ms, p < 0.05), whereas CRTfw and CRTa restored regional thickening to RA pacing levels (194 + or - 83%.ms and 230 + or - 76%.ms, respectively). The sum of thickening and thinning during RV (230 + or - 88%.ms vs. 258 + or - 133%.ms, p < 0.05) correlated (r = 0.98) with RA thickening, suggesting that all the loss of LV function was due to thinning. Dyssynchrony causes proportional changes in regional LV wall thinning and global LV SW that were reversed by CRT, suggesting that dyssynchrony impairs LV systolic function by causing paradoxical regional wall thinning and that CRT effectiveness can be monitored by its reversal. Thus, monitoring paradoxical regional thinning reversal may be used to define CRT effectiveness.

Echocardiographic Tissue Deformation Imaging Quantifies Abnormal Regional Right Ventricular Function in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy

The aim of this study was to determine the accuracy of new quantitative echocardiographic strain and strain-rate imaging parameters to identify abnormal regional right ventricular (RV) deformation associated with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). A total of 34 patients with ARVD/C (confirmed by Task Force criteria) and 34 healthy controls were prospectively enrolled. Conventional echocardiography, including Doppler tissue imaging (DTI), was performed. Doppler and two-dimensional strain-derived velocity, strain, and strain rate were calculated in the apical, mid, and basal segments of the RV free wall. RV dimensions were significantly increased in patients with ARVD/C (RV outflow tract 19.3+/-5.2 mm/m2 vs 14.1+/-2.2 mm/m2, P<.001; RV inflow tract 23.4+/-4.8 mm/m2 vs 18.8+/-2.4 mm/m2, P<.001), whereas left ventricular dimensions were not significantly different compared with controls. Strain and strain rate values were significantly lower in patients with ARVD/C in all 3 segments. All deformation parameters showed a higher accuracy to detect functional abnormalities compared with conventional echocardiographic criteria of dimensions or global systolic function. The lowest DTI strain value in any of the 3 analyzed segments showed the best receiver operating characteristics (area under the curve 0.97) with an optimal cutoff value of -18.2%. DTI and two-dimensional strain-derived parameters are superior to conventional echocardiographic parameters in identifying ARVD/C. This novel technique may have additional value in the diagnostic workup of patients with suspected ARVD/C.

Echocardiographic Strain Imaging to Assess Early and Late Consequences of Sarcomere Mutations in Hypertrophic Cardiomyopathy

Genetic testing identifies sarcomere mutation carriers (G+) before clinical diagnosis of hypertrophic cardiomyopathy (HCM), allowing characterization of initial disease manifestations. Previous studies demonstrated that impaired relaxation develops before left ventricular hypertrophy (LVH). The precise impact of sarcomere mutations on systolic function in early and late disease is unclear. Comprehensive echocardiography with strain imaging was performed on 146 genotyped individuals with mutations in 5 sarcomere genes. Contractile parameters were compared in 68 preclinical (G+/LVH-), 40 overt (G+/LVH+) subjects with HCM, and 38 mutation (-) normal control relatives. All subjects had normal left ventricular ejection fraction. In preclinical HCM, global and regional peak systolic strain (epsilon(sys)) and longitudinal systolic strain rate were not significantly different from controls, but early diastolic mitral annular velocity (Ea) was reduced by 13%. In overt HCM, there was a significant 27% and 14% decrease in global longitudinal epsilon(sys) and systolic strain rate, respectively, compared with both preclinical HCM and controls (P<0.013 for all comparisons), and a 33% reduction in Ea. Sarcomere mutations have disparate initial effects on diastolic and systolic functions. Preclinical HCM is characterized by impaired relaxation but preserved systolic strain. In contrast, both diastolic and longitudinal systolic abnormalities are present in overt disease despite normal ejection fraction. We propose that diastolic dysfunction is an early consequence of sarcomere mutations, whereas systolic dysfunction results from mutations combined with subsequent pathological remodeling. Identifying mechanistic pathways triggered by these mutations may begin to reshape the clinical paradigm for treatment, based on early diagnosis and disease prevention.

Validation of Echocardiographic Two-Dimensional Speckle Tracking Longitudinal Strain Imaging for Viability Assessment in Patients With Chronic Ischemic Left Ventricular Dysfunction and Comparison With Contrast-Enhanced Magnetic Resonance Imaging

The purpose of the present study was to compare longitudinal strain assessed by two-dimensional speckle tracking with scar tissue on contrast-enhanced magnetic resonance imaging (MRI) in patients with chronic ischemic left ventricular (LV) dysfunction. The aim was also to define a cutoff value for regional strain to discriminate between viable myocardium and transmural scar. Ninety patients with chronic ischemic LV dysfunction underwent transthoracic echocardiography to measure global and segmental (regional) longitudinal LV strain using two-dimensional speckle tracking and cine MRI followed by contrast-enhanced MRI to assess segmental LV function and the segmental/global (transmural) extent of scar tissue. The optimal cutoff value for regional strain to discriminate between segments with viable myocardium and segments with transmural scar was also determined. A good correlation was found between global LV strain and the global extent of scar tissue on contrast-enhanced MRI (R = 0.62, p <0.001). The mean segmental strain in segments without scar tissue was -10.4% +/- 5.2% compared with 0.6% +/- 4.9% in segments with transmural scar tissue (p <0.001). A strain value of -4.5% discriminated between segments with viable myocardium and segments with transmural scar tissue on contrast-enhanced MRI with a sensitivity of 81.2% and specificity of 81.6%. In conclusion, global and regional longitudinal strain measured with two-dimensional speckle tracking is associated with the global and regional (transmural) extent of scar tissue on contrast-enhanced MRI. A cutoff value of -4.5% for regional strain discriminated between segments with viable myocardium and those with transmural scar tissue on contrast-enhanced MRI with a sensitivity of 81.2% and specificity of 81.6%.

Strain and Strain Rate Imaging by Echocardiography - Basic Concepts and Clinical Applicability

Echocardiographic strain and strain-rate imaging (deformation imaging) is a new non-invasive method for assessment of myocardial function. Due to its ability to differentiate between active and passive movement of myocardial segments, to quantify intraventricular dyssynchrony and to evaluate components of myocardial function, such as longitudinal myocardial shortening, that are not visually assessable, it allows comprehensive assessment of myocardial function and the spectrum of potential clinical applications is very wide. The high sensitivity of both tissue Doppler imaging (TDI) derived and two dimensional (2D) speckle tracking derived myocardial deformation (strain and strain rate) data for the early detection of myocardial dysfunction recommend these new non-invasive diagnostic methods for extensive clinical use. In addition to early detection and quantification of myocardial dysfunction of different etiologies, assessment of myocardial viability, detection of acute allograft rejection and early detection of allograft vasculopathy after heart transplantation, strain and strain rate data are helpful for therapeutic decisions and also useful for follow-up evaluations of therapeutic results in cardiology and cardiac surgery. Strain and strain rate data also provide valuable prognostic information, especially prediction of future reverse remodelling after left ventricular restoration surgery or after cardiac resynchronization therapy and prediction of short and median-term outcome without transplantation or ventricular assist device implantation of patients referred for heart transplantation.The Review explains the fundamental concepts of deformation imaging, describes in a comparative manner the two major deformation imaging methods (TDI-derived and speckle tracking 2D-strain derived) and discusses the clinical applicability of these new echocardiographic tools, which recently have become a subject of great interest for clinicians.

Two‐dimensional, Non‐Doppler Strain Imaging during Anesthesia and Cardiac Surgery

Transesophageal echochardiography (TEE) has become an essential intraoperative monitor during general anesthesia for cardiac surgical procedures. In clinical practice, ventricular function is visually evaluated using gray scale and Doppler modes, despite the fact that subjective interpretation is influenced by level of experience and training. Echocardiographic strain imaging measures cardiac deformation and provides objective quantification of regional myocardial function. Non-Doppler strain, which is derived by tracking speckles from two-dimensional (2D) images, bypasses the limitations of Doppler-based strain measurements and evaluates the complex myocardial deformation along three dimensions. As a result, longitudinal shortening, circumferential thinning and radial thickening can be quantified using standard midesophageal and transgastric views, being acquired during a comprehensive TEE examination. Once non-Doppler strain becomes available on "real time," it will have the potential to become a valuable tool for detection of ischemia on the regional level and objective quantification of global ventricular function.

Echocardiographic Speckle Tracking Radial Strain Imaging to Assess Ventricular Dyssynchrony in a Pacing Model of Resynchronization Therapy

Speckle tracking imaging is a promising new echocardiographic method to assess left ventricular (LV) mechanical dyssynchrony. Our aim was to assess a new speckle tracking regional strain algorithm by comparison with angle-corrected tissue Doppler (TD) in an animal model of left bundle branch block and cardiac resynchronization therapy. Ten open-chest dogs had routine gray-scale and TD images of the mid-LV short-axis plane. Electrical activation was altered by pacing from right ventricular, LV free wall, and biventricular sites to create various degrees of mechanical dyssynchrony and alter regional function. Segmental time to peak strain, peak strain, and frame-by-frame strain were measured by angle-corrected TD, TD M-mode, and speckle tracking on the same digital cineloop. Of 240 possible paired TD and speckle tracking segments, data were available for 222 segments (93%); images with catheter artifacts were prospectively excluded. Comparative overall time to peak strain by each method correlated well: r = 0.96, bias = -6 +/- 20 ms. Of 80 possible paired M-mode TD and speckle tracking segments, strain data were available for 76 segments (95%). Comparative overall time to peak strain, peak strain, and frame-by-frame strain analysis in 1012 frames by each method correlated well: r = 0.98, bias of 1 +/- 14 ms; r = 0.82, bias of 3% +/- 7%; and r = 0.91, bias of 0% +/- 6%, respectively. Regional strain analysis using echocardiographic speckle tracking radial strain strongly correlated with strain by angle-corrected TD imaging in an animal model of dyssynchrony. Speckle tracking radial strain has potential for clinical applications.

Differentiation of Hypertrophic Cardiomyopathy and Cardiac Amyloidosis from Other Causes of Ventricular Wall Thickening by Two-Dimensional Strain Imaging Echocardiography

Hypertension is the most common cause of left ventricular (LV) hypertrophy. However, multiple causes can lead to LV hypertrophy, each of which has different histological and mechanical properties. To assess the value of a novel speckle-tracking echocardiographic measurement of myocardial strain and strain rate in defining the mechanical properties of LV hypertrophy, 20 patients with asymmetric hypertrophic cardiomyopathy, 24 patients with secondary LV hypertrophy, 12 patients with biopsy-proved confirmed cardiac amyloidosis, and 22 age-matched healthy asymptomatic volunteers were studied. Patients with amyloidosis had severe diastolic dysfunction, and myocardial deformation was significantly decreased. The new technique allowed cardiac amyloid to be easily differentiated from the other categories. In patients with hypertrophic cardiomyopathy, there was segmental myocardium dysfunction as assessed by strain imaging. LV global systolic velocity and radial displacement were higher, and abnormal relaxation was more frequent, in the group with secondary LV hypertrophy than in normal controls. In conclusion, the observations from strain parameters derived from speckle tracking were consistent with the known underlying pathology of each condition, which speaks to the value of strain imaging. Cardiac amyloid profoundly alters all strain parameters, and analysis of these parameters could aid in the diagnosis.

Velocity and deformation imaging for the assessment of myocardial dysfunction

Recent developments in echocardiographic imaging technology and processing enabled the quantification of myocardial motion and deformation in a clinical setting. Echocardiographic strain (-rate) imaging provides a relatively easy way to study myocardial deformation. However, although (local) deformation is clearly linked to cardiac (dys-) function, it is important to understand how this information can be used in clinical practice and how specific deformation patterns should be interpreted. This review paper first discusses which issues are important to address when assessing cardiac function and how (regional) deformation and myocardial contractility are related. The use and interpretation of deformation profiles is further illustrated for some typical cardiac pathologies. The observed deformation patterns are discussed in light of the changes in regional contractility (ischemia), timing of contractile force development (LBBB and heart failure), pressure/volume overload, and assessing diastolic function.

Left Atrial Dyssynchrony in Patients With Nonobstructive Hypertrophic Cardiomyopathy Evaluated by Myocardial Strain Imaging

Background. The present study was conducted to examine left atrial (LA) dyssynchrony, determined by echocardiographic myocardial strain imaging, in patients with hypertrophic cardiomyopathy (HCM). Methods. We studied 26 patients with HCM (20 men and 6 women, age, 66±7 years) and 25 normal subjects (controls). Tissue Doppler-based strain images were recorded in the apical 2-, 4-chamber, and long-axis views. The LA strain curve was obtained with the region of interest placed at the 5 LA segments, namely, the atrial septum, lateral wall, inferior wall, anterior wall, and posterior wall. We measured standard deviation (SD) of the time-periods between aortic valve opening and maximal strain (reservoir dyssynchrony index) and SD of the time-periods between mitral valve opening and minimal strain (emptying dyssynchrony index).Results. Compared with controls, patients with HCM had greater indexes of reservoir (40±23 ms vs. 23±8 ms, p=0.001) and emptying (37±17 ms vs. 28±11 ms, p=0.02) dyssynchrony. Reservoir dyssynchrony (index >39 ms) was detectable in 11 patients, and emptying dyssynchrony (index >50 ms) was detectable in 5 patients. Patients with reservoir dyssynchrony had a greater LV mass index than those without (182±45 g/m2 vs. 142±32 g/m2, p=0.01), whereas patients with emptying dyssynchrony had greater LA minimal volume (39±12 ml/m2 vs. 26±10 ml/m2 p=0.02) and lower LA emptying fraction than those without (27±3% vs. 39±11%, p=0.02).Conclusions. LA dyssynchrony can be present throughout the cardiac cycle in patients with HCM. LA dyssynchrony is more common in the reservoir phase and may be attributed to significant myocardial involvement.

Detection of Subclinical Cardiac Involvement in Systemic Sclerosis by Echocardiographic Strain Imaging

Cardiac involvement is one of the major problems in systemic sclerosis (SSc). Subclinical cardiac involvement has a higher frequency than thought previously. In this study we investigated whether subclinical cardiac involvement can be detected by using echocardiographic strain imaging in SSc patients without pulmonary hypertension. Echocardiographic examinations were performed to 27 SSc patients and 26 healthy controls. Left ventricular strain parameters were obtained from apical views and average strain value was calculated from these measurements. There were no significant differences between patients and controls regarding two-dimensional (2D), conventional Doppler and tissue Doppler velocity measurements. Strain was reduced in 6 of 12 segments of the left ventricle (LV) and in 1 of 2 segments of the right ventricle (RV). Strain rate (SR) was reduced in 2 of 12 segments of the LV and 1 of 2 segments of the RV in SSc patients as compared to controls (P < 0.05 for all). These involvements did not match any particular coronary artery distribution. More important differences were detected by average strain and SR values of the LV between patients and controls (19.78 +/- 3.00% vs 23.41 +/- 2.73%, P < 0.001; 2.01 +/- 0.41 vs 2.23 +/- 0.27/sec, P = 0.026, respectively). Furthermore, carbon monoxide diffusion capacity (DLCO) in scleroderma patients significantly correlated with LV average strain (r = 0.59; P = 0.001). Evaluation of ventricular function by using echocardiographic strain imaging appears to be useful to detect subclinical cardiac involvement in SSc patients with normal standard echocardiographic and tissue Doppler velocity findings.

Alterations of Regional Myocardial Function in a Swine Model of Myocardial Infarction Assessed by Echocardiographic 2-Dimensional Strain Imaging

Tissue Doppler strain and strain rate imaging have been introduced for quantitative assessment of regional myocardial function. These techniques are largely limited to the evaluation of overall longitudinal myocardial function. This study attempted to apply radial strain, circumferential strain, radial displacement, and strain-based torsion analysis to differentiating the infarct, adjacent, and remote zones in a swine model of myocardial infarction. Seven pigs, body weight 24 to 26 kg, were subjected to myocardial infarction by occlusion of the left anterior descending coronary artery (LAD) and followed up for 8 weeks. Regional radial and circumferential deformations were quantified noninvasively by ultrasonic strain rate imaging before LAD occlusion, LAD occlusion immediately, and 4, 6, and 8 weeks after LAD occlusion. Strain-based left ventricular torsion was assessed at the same time points. Both radial and circumferential strains, and torsion, were decreased significantly in the LAD territory areas as a result of myocardial ischemia and infarction. There were no significant changes in radial and circumferential strains, or torsion, in the areas of adjacent and remote zones over time. These findings demonstrate that speckle-tracking strain imaging may be suitable for noninvasive quantification of left ventricular segmental function of ischemic heart disease.

Effect of Medical Therapy for Heart Failure on Segmental Myocardial Function in Patients With Ischemic Cardiomyopathy

The adjustment of medications and dosages to the needs of individual patients with heart failure is mostly intuitive, but even when their effect on global myocardial function is measured by classic indexes, their effect on segmental function is overlooked. This study was conducted to assess the feasibility of using echocardiographic myocardial strain imaging to evaluate the effect of medication on global and segmental function in 21 ambulatory patients with heart failure (mean age 65+/-11 years) who had echocardiographic studies performed before and 2 hours after ingesting their regular morning medications. The ejection fraction, global and regional strain, and time to regional peak strain were compared between the 2 examinations. Medication induced no significant changes in mean ejection fraction (28.6+/-7.8% to 27.5+/-9.9%) and mean global strain (-9.5+/-3.6% to -9.8+/-3.2%). Changes in segmental strain depended on baseline function: normal segments (peak strain more negative than -12%) deteriorated (-15.5+/-2.7% to -13.7+/-4.6%, p<0.0001), but dysfunctional segments (peak strain less negative than -8%) improved (-5.3+/-2.0% to -7.4+/-4.3%, p<0.0001). Medication also improved segmental synchronization: average time to peak strain of segments in which peak strain was attained before aortic valve closure increased (325+/-69 to 375+/-100 ms, p<0.0001), but that of segments with postsystolic shortening at baseline decreased (451+/-93 to 435+/-93 ms, p<0.006). Thus, the time interval between time to peak strain of segments with systolic and post-systolic shortening at baseline was halved after medication. In conclusion, medications for heart failure induced an increase in the echocardiographically determined peak strain of myocardial segments with impaired function at baseline but decreased the peak strain of normally contracting segments. Medications also improved the synchronization of myocardial contraction. Neither the global ejection fraction nor global strain reflected these changes. Thus, medication tended to improve the homogeneity of left ventricular contraction.

Improvement of left ventricular mechanical dyssynchrony associated with restoration of left ventricular function in a patient with fulminant myocarditis and complete left bundle branch block

A 52-year-old woman with fulminant myocarditis had completed left bundle branch block (LBBB) and severely impaired left ventricular (LV) function. Marked mechanical dyssynchrony with septal-to-posterior delay of 389 ms was observed by echocardiographic speckle tracking radial strain imaging on admission, which was dramatically improved to 106 ms after total recovery from acute myocarditis with restoration of LV ejection fraction whereas her electrocardiogram still showed complete LBBB.

Right Ventricular Tissue Doppler and Strain Imaging: Ready for Clinical Use?

Although tissue Doppler (TD) imaging of the left ventricle is now commonly used in clinical settings, TD imaging of the right ventricle (RV) is not routinely practiced. Yet, there are significant data on clinical uses of RV TD imaging, including established normal values using both color and spectral TD. In acute left ventricular (LV) inferior wall myocardial infarction, depressed RV TD velocities have been shown to correlate with the presence of RV impairment, and with patient outcome. In patients with LV heart failure, TD imaging has been correlated to RV ejection fraction by radionuclide angiography, and is an independent predictor of outcome. In patients with congenital heart disease, RV TD has been especially valuable for assessing RV function, and has been correlated to invasive hemodynamic indices, and RV ejection fraction by magnetic resonance imaging. The RV performance (Tei) index has been calculated and validated using TD-derived, rather than conventional pulsed Doppler time intervals. RV TD indices have been shown to be useful in the detection of subclinical and clinical disease in morbid obesity, chronic pulmonary, and systemic disease. TD-derived RV strain imaging can detect segmental myocardial dysfunction, overcoming limitations to conventional TD imaging resulting from tethering. For both TD velocity and strain imaging, however, appreciation of the limitations of these techniques is necessary for their appropriate use. Given its rapid acquisition times, reproducibility, and ease of addition to standard transthoracic echocardiographic protocols, RV TD and strain imaging are important additional modalities in the comprehensive echo-Doppler assessment of RV function.

Effects of Dual-Chamber Pacing on Regional Myocardial Deformation in Patients With Hypertrophic Obstructive Cardiomyopathy

This study examined the effects of dual-chamber pacing (DDD) on regional myocardial deformation, as determined by echocardiographic strain and strain rate (SR) imaging, in patients with hypertrophic obstructive cardiomyopathy (HOCM). Fourteen patients (11 men, 3 women; mean age 55 +/-16 years) who had been on long-term DDD (mean period 7.4 +/- 2.1 years) underwent strain and SR imaging. Before and after DDD, the peak strain (%) and SR (s(-1)) during systole were assessed in 8 segments in 4 left ventricular (LV) walls. With DDD turned on, peak strain and SR were significantly increased in the basal anteroseptal (strain -10.2 +/- 6.8 to -1.0 +/- 6.4, p<0.005; SR -0.76 +/- 0.46 to 0.05 +/- 0.58, p<0.001) and septal segments (strain -11.2 +/- 8.9 to -2.2 +/- 7.7, p<0.005; SR -0.85 +/- 0.54 to -0.19 +/- 0.75, p<0.05), but not in the basal posterior (strain -15.0 +/- 13.0 to -13.4 +/- 9.2, p=NS; SR -1.37 +/- 0.57 to -1.93 +/- 0.65, p=NS) and lateral segments (strain -18.1 +/- 10.2 to -15.7 +/- 5.6, p=NS; SR -1.33 +/- 0.68 to -0.84 +/- 0.88, p=NS). These findings were associated with a modest, but significant, change in the LV pressure gradient (24 +/- 12 mmHg to 14 +/- 7 mmHg, p<0.001). In patients with HOCM, DDD appeared to produce myocardial lengthening in the basal septum during systole, which may have implications for the mechanism of reducing LV outflow obstruction during DDD.

Echocardiographic Strain Imaging for Myocardial Viability

Echocardiographic strain imaging was introduced by Heimdal et al in 19981 as a means to calculate myocardial regional function from tissue Doppler velocity data.2,3 Strain imaging is a variation of the previous concept of tissue Doppler myocardial velocity gradient, which calculates regional thickening independent of passive whole heart motion.4,5 Because routine clinical evaluation of regional function is usually by visual wall-motion assessment, strain imaging has great promise to improve objective quantification of regional function. Strain imaging calculates deformation, which translates clinically to percent shortening in the longitudinal dimension (assessed from apical views) or percent thickening in the radial dimension (assessed from parasternal views).1,6,7 Theoretically, it has the important advantage of differentiating active myocardial motion from passive translational or tethering movements that other echocardiographic-Doppler approaches cannot differentiate. Indeed, there have been literally hundreds of publications over the last 10 years detailing a wide range of experimental and potential clinical applications of strain imaging; however, currently, few centers have adopted strain imaging in their routine clinical practice, preferring visual “eyeball” assessment, even though this is inherently subjective and requires a high level of experience and training.8 An important question remains: Is it now time for strain imaging to be adopted in a widespread clinical sense? Articles pp 3892 and 3901 Two important articles are contained in this issue of Circulation that address the application of strain imaging as a tool to assess myocardial viability: an animal study of experimental ischemia and infarction by Lyseggen et al9 and a clinical study using dobutamine echocardiography with outcome data after revascularization by Hanekom et al.10 The article by Lyseggen et al illustrates the additive value of strain imaging in an elegant open-chest animal model of coronary occlusion and reperfusion. Echocardiographic strain imaging was performed along with simultaneous dimensional …

Assessment of left ventricular longitudinal regional myocardial systolic function by strain imaging echocardiography in patients with hypertrophic cardiomyopathy.

To assess the left ventricular longitudinal regional myocardial systolic function by strain imaging (SI) echocardiography and to study the relationship between regional myocardial systolic function and left ventricular structure in patients with hypertrophic cardiomyopathy (HCM). SI echocardiography were performed in 18 patients with HCM and 17 healthy subjects. For each wall, regional myocardial systolic strain was analyzed at the basal, mid, and apical level respectively. And the peak systolic strain was measured. Our results showed that the patients with HCM had reduced peak systolic strain at almost each segment of different walls when compared with healthy subjects. There was significant correlation between the mid-septum peak systolic strain and the thickness of IVS, so was the correlation between the mid-septum peak systolic strain and the IVS to LVPW thickness ratio. This study demonstrated that the left ventricular longitudinal regional myocardial systolic function was abnormal in HCM, and this kind of abnormalities existed extensively in hypertrophic and non-hypertrophic cardiac segments. The degrees of left ventricle hypertrophy and asymmetry are related to the myocardial regional systolic function in HCM.

Utility of Echocardiographic Radial Strain Imaging to Quantify Left Ventricular Dyssynchrony and Predict Acute Response to Cardiac Resynchronization Therapy

Echocardiographic strain imaging was used to quantify radial mechanical dyssynchrony in 38 patients who underwent cardiac resynchronization therapy. Dyssynchrony, defined as the time difference of peak radial strain in the septum versus the posterior wall, was significantly greater in patients with acute hemodynamic responses, and changes in radial dyssynchrony correlated with changes in stroke volume. A > or =130-ms difference in septal versus posterior wall peak strain when combined with a favorable left ventricular lead position was strongly predictive of immediate improvement in stroke volume with resynchronization therapy (95% sensitivity, 88% specificity), regardless of electrocardiographic QRS duration.

A mechanism for immediate reduction in mitral regurgitation after cardiac resynchronization therapy: Insights from mechanical activation strain mapping

We tested the hypothesis that an immediate reduction in mitral regurgitation (MR) after cardiac resynchronization therapy (CRT) results from improved coordinated timing of the papillary muscle insertion sites, using the novel approach of mechanical activation strain mapping. Heart failure patients with left bundle branch block often benefit acutely from CRT; however, the role and mechanism of reduction of MR are unclear. Twenty-six consecutive patients undergoing CRT with at least mild MR were studied (ejection fraction 24 +/- 6%; QRS duration 168 +/- 30 ms). Echocardiographic Doppler and strain imaging was performed immediately before and the day after CRT, as well as in 10 normal control subjects. Mechanical activation sequence maps were constructed using longitudinal strain from 12 basal and mid-LV sites, with color coding of time-to-peak strain. Mitral regurgitation by the volumetric method consistently decreased after CRT: regurgitant volume from 40 +/- 20 ml to 24 +/- 17 ml and regurgitant fraction from 40 +/- 12% to 25 +/- 14% (both: p < 0.001 vs. baseline). Normal controls had uniform segmental time-to-peak strain, with a difference of only 12 +/- 8 ms between all segments. In contrast, CRT patients at baseline had a 106 +/- 74 ms time delay between papillary muscle insertion sites (p < 0.001 vs. normal). This interpapillary muscle time delay shortened after CRT to 39 +/- 43 ms (p < 0.001 vs. baseline) and was significantly correlated with reductions in mitral regurgitant fraction (r = 0.77, p < 0.001). Cardiac resynchronization therapy significantly and immediately reduced MR. Improved coordinated timing of mechanical activation of papillary muscle insertion sites appears to be a mechanistic contributor to immediate MR reduction by CRT.