Role of Echocardiography in Assessment of Cardioembolic Sources: a Strong Diagnostic Resource in Patients with Ischemic Stroke.

PURPOSE OF REVIEW: This review will discuss the most frequent sources of cardiac embolism and the role of echocardiography in these different clinical settings, and, in addition, provide suggestions about the choice between transthoracic (TTE) and transesophageal echocardiography (TEE). RECENT FINDINGS: Stroke is the third leading cause of death in industrial countries, and 15-40% of all ischemic strokes are due to cardioembolism. TTE and TEE are cornerstones in the detection of cardioembolic sources and provide fundamental information about the embolic risk and most suitable treatment of these patients, improving long-term outcomes. Echocardiography is a widely available, inexpensive, and safe diagnostic tool that is almost free from contraindication, and these elements allow the common use of this technique in almost all the patients with ischemic stroke. The most common cardioembolic sources include left atrial appendage thrombosis during atrial fibrillation; vegetations in infective endocarditis; cardiac masses including left ventricular thrombosis, cardiac tumors, etc.; atherosclerotic plaques; and passageways within the heart serving as conduits for paradoxical embolization, e.g., patent foramen ovale.

Role of Echocardiography in the Intensive Care Unit: Overview of the Most Common Clinical Scenarios.

The intensive care unit (ICU) is among the more important settings in which echocardiography plays a pivotal role. The ease of use, speed of execution, and completeness of information on heart anatomy and function that echocardiography is able to provide makes this tool the perfect diagnostic technique in patients for whom exhaustive information must be quickly obtained by physicians who sometimes lack specific skills in cardiovascular imaging. However, the clinical entities encountered by ICU clinicians are often difficult to distinguish and patient symptoms may not be obvious. This brief review describes three common clinical scenarios that benefit from echocardiography in the ICU, based on symptoms frequently claimed by patients admitted to the ICU. For each symptom we describe the most likely clinical possibilities, underlining the fundamental role that echocardiography plays in the differential diagnosis, and the echocardiographic elements most relevant to obtain the correct diagnosis and to guide treatment.

Left ventricular rotational mechanics before and after exercise in children.

BACKGROUND: In children, there is limited information regarding the relative contribution of left ventricular (LV) apical and basal rotation to increase LV pump function with exercise. The aim of this study was to test the hypothesis that a progressive increase in LV pump function with exercise is related to increased LV apical and basal rotation. METHODS: Forty-two subjects 12 to 18 years of age with normal cardiac structure and function were recruited prospectively and imaged at rest, and in 20 subjects, imaging was repeated after moderate exercise. Conventional measures of LV systolic and diastolic performance were evaluated. Left ventricular rotation, LV twist, rotational rate, and recoil and untwist rates were measured using two-dimensional speckle-tracking echocardiography. Torsion was calculated by normalizing LV twist to LV diastolic length. Twist displacement loops were constructed from data obtained at rest and after exercise. RESULTS: Apical rotation increased significantly after exercise (7.33 ± 2.8° vs 11.6 ± 4.7°, P = .0004), but basal rotation did not (-4.85 ± 1.9 vs -6.46 ± 4.81, P = .21). Similarly, peak twist, torsion, and twist rate also increased significantly after exercise. In diastole, apical recoil rate and LV untwist rate also increased significantly with exercise. The slope of the systolic limb of the twist displacement loop and the area enclosed by the loop also increased significantly with exercise. CONCLUSIONS: Increases in global LV pump function during exercise in children are associated with enhanced LV apical rotation but not LV basal rotation. In addition, unique changes were seen in twist displacement loops in children before and after exercise. These data may serve as a foundation for understanding future applications of LV rotational mechanics in disease states.

Three-dimensional principal strain analysis for characterizing subclinical changes in left ventricular function.

BACKGROUND: Subendocardial strain analysis is currently feasible in two-dimensional and three-dimensional (3D) echocardiography; however, there is a lack of clarity regarding the most useful strain component for subclinical disease detection. The aim of this study was to test the hypothesis that strain analysis along the direction of strongest and weakest systolic compression (referred to as principal and secondary strain, respectively) circumvents the need for multidirectional strains and provides a more simplified assessment of left ventricular subendocardial function. METHODS: Strain analyses were performed by using two-dimensional and 3D echocardiography in 41 consecutive subjects with normal results on electron-beam computed tomography, including 15 controls and 26 patients with systemic hypertension. The direction of principal strain referenced the myofiber geometry obtained from diffusion tensor magnetic resonance imaging of a normal autopsied human heart. The incremental value of principal strain over multidirectional two-dimensional and 3D strain was analyzed. RESULTS: In healthy subjects, 50 ± 3% of the subendocardial shortening occurred in the cross-fiber direction (left-handed helical); this balance was significantly altered in patients with hypertension (P = .01). The magnitude of longitudinal and circumferential strain was similar in patients with hypertension and controls. However, the alteration of the directional contraction pattern resulted in reduced secondary strain magnitude in patients with hypertension (P = .01), and the differences were further exaggerated when the secondary strain was normalized by the principal strain magnitude (P = .004). CONCLUSIONS: Two-component principal and secondary strain analysis can be related to left ventricular myofiber geometry and may simplify the assessment of 3D left ventricular deformation by circumventing the need to assess multiple shortening and shear strain components.

Assessment of longitudinal myocardial mechanics in patients with degenerative mitral valve regurgitation predicts postoperative worsening of left ventricular systolic function.

BACKGROUND: The optimal timing of mitral valve repair (MVr) in patients with chronic severe degenerative mitral regurgitation (MR) remains controversial and is broadly based on either measurable loss of systolic function, as determined by left ventricular (LV) ejection fraction (LVEF) and/or LV chamber remodeling. The aim of this study was to test the hypothesis that the assessment of LV deformation by speckle-tracking echocardiography might uncover subclinical changes for predicting reduction of LVEF after MVr. METHODS: One hundred thirty patients (mean age, 57 ± 14 years; 85 men) who underwent MVr for chronic severe degenerative MR were retrospectively identified. Baseline and immediate postoperative transthoracic echocardiography was used to assess global longitudinal strain (GLS), global radial strain, and global circumferential strain before and after MVr. RESULTS: In comparison with baseline, MVr resulted in significant reductions in LVEF (P < .0001) and in GLS (P < .0001). Postoperative change in LVEF was related to the changes in GLS (r = -0.71, P < .0001) and global circumferential strain (r = -0.22, P = .01) but not global radial strain. For the entire group, the presence of a high preoperative GLS magnitude predicted a postoperative reduction in LVEF of >10% (odds ratio, 0.80; P < .001). Furthermore, GLS showed diagnostic value in predicting a reduction in LVEF of >10% with a resulting postoperative LVEF of <50% (area under the curve, 0.93; P < .001). CONCLUSIONS: In chronic severe degenerative MR, disproportionately higher LV global longitudinal strain signifies a maladaptive preload-related change that is associated with substantial loss of LVEF immediately after MVr. Preoperative assessment of longitudinal strain may be potentially useful for optimizing the timing of MVr for degenerative MR.

Effect of head-up tilt-table testing on left ventricular longitudinal strain in patients with neurocardiogenic syncope.

Recent studies have shown conflicting data regarding left ventricular (LV) function in patients with neurocardiogenic syncope, with some investigators reporting a marked decrease in LV end-systolic wall stress and stress-corrected fractional shortening. We sought to determine the characteristics of resting LV deformation in patients with neurocardiogenic syncope by selective motion tracking of subendocardial and subepicardial regions using speckle tracking echocardiography. We assessed resting LV function in 82 patients undergoing head-up tilt-table (HUTT) testing. Patients were divided into 3 groups based on a positive HUTT test with associated co-morbid conditions (n = 30), no associated co-morbid conditions (n = 30), or negative HUTT results (n = 22). LV longitudinal, circumferential, and radial strains were obtained by speckle tracking echocardiography of subendocardial and subepicardial regions in each group and compared with resting LV deformation in 20 healthy control subjects. Compared with endocardial longitudinal strain in control subjects, that in patients with positive HUTT results was attenuated, irrespective of co-morbid conditions (p <0.05). Circumferential and radial strains did not differ among groups. On multivariate logistic regression analysis, endocardial longitudinal strain was an independent predictor (odds ratio, 1.16; p = 0.01) of positive HUTT test results. In conclusion, resting LV longitudinal strain is attenuated in patients with positive HUTT test results. Overall, these results may suggest that an increase in resting LV contractility is not a prerequisite for development of neurocardiogenic syncope.

Myocardial stretch in early systole is a key determinant of the synchrony of left ventricular mechanical activity in vivo.

BACKGROUND: Recent in-vitro observations suggest that left ventricular (LV) contraction is powered by 'stretch activation', an intrinsic mechanism by which the stretching of an activated cardiomyocyte causes delayed force redevelopment. We hypothesized that mechanical dyssynchrony is related to prolonged early systolic stretch that delays the timing of peak segmental shortening. METHODS AND RESULTS: The time intervals from R wave to segmental longitudinal stretch in early systole (Tstretch) and peak shortening (Tpeak) and the respective standard deviations (σTstretch and σTpeak) were measured by speckle-tracking echocardiography in 57 patients undergoing cardiac resynchronization therapy (CRT). The percentage of time spent in shortening, normalized to Tpeak duration [corrected ΔT=(Tpeak-Tstretch)/Tpeak] correlated with LV reverse remodeling (reduction in end-systolic volume ≥ 15%). Of the 57 patients, 40 (70.2%) demonstrated LV reverse remodeling at an average follow-up of 263 ± 125 days after CRT. At baseline, Tstretch and σTstretch correlated with Tpeak and σTpeak, respectively. Though there was no difference in Tstretch, Tpeak, σTstretch and σTpeak between responders and non-responders, corrected ΔT in the mid-lateral and mid-septal segments was shorter in the responders (P<0.05 for both) and the average of the 2 independently predicted LV reverse remodeling (area under the curve: 0.77, P=0.001). CONCLUSIONS: Mapping LV segmental shortening in relation to early systolic stretch may aid dyssynchrony assessment in patients undergoing CRT.

CRT improves LV filling dynamics: insights from echocardiographic particle imaging velocimetry.

Echocardiographic particle imaging velocimetry allows blood flow visualization and characterization of diastolic vortex formation that may play a key role in filling efficiency. We hypothesized that abrupt withdrawal of cardiac resynchronization therapy (CRT) would alter the timing of left ventricular diastolic vortex formation and modify cardiac time intervals. In patients with heart failure (HF) who had chronically implanted CRT devices, the timing of the onset of the diastolic vortex (TDV) from mitral valve opening, transmitral flow, and cardiac time intervals was measured at baseline and after deactivation and reactivation of CRT. Compared with control patients with cardiovascular risk factors but structurally normal hearts, TDV was significantly delayed in patients with HF. Deactivation of CRT resulted in striking delay in TDV due to disorganized flow and reduced flow acceleration, and reactivation reversed these characteristics instantly. In addition, CRT deactivation also prolonged the isovolumic contraction interval, which closely correlated with the changes in the TDV. These data suggest that CRT plays an important role in optimization of left ventricular diastolic filling.

Contrast echocardiography for assessing left ventricular vortex strength in heart failure: a prospective cohort study.

AIMS: This study investigated the incremental role of echocardiographic-contrast particle image velocimetry (Echo-PIV) in patients with heart failure (HF) for measuring changes in left ventricular (LV) vortex strength (VS) during phases of a cardiac cycle. METHODS AND RESULTS: Echo-PIV was performed in 42 patients, including 23 HF patients and 19 controls. VS was measured as a fluid-dynamic parameter that integrates blood flow rotation over a given area and correlated with non-invasively derived indices of LV mechanical performance. In comparison with early and late diastole, the VS was higher during isovolumic contraction (IC) for control and HF patients with the preserved ejection fraction (P = 0.002 and P = 0.01, respectively), but not for HF patients with the reduced ejection fraction (P = 0.41). On multivariable regression analysis, the VS during IC (VSIC) was independently related to late-diastolic VS and LV longitudinal strain (R(2)= 0.63, P < 0.001 and P = 0.003, respectively). Patients in whom diastolic VS was augmented during IC showed a higher LV stroke volume (P = 0.01), stroke work (P = 0.02), and mechanical efficiency (P = 0.008). Over a median follow-up period of 2.9 years, eight (34%) HF patients were hospitalized for decompensated HF. In comparison with the rest, these eight patients showed markedly reduced longitudinal strain (P = 0.002), and lower change in VS (P = 0.004). CONCLUSION: Our preliminary data suggest that the persistence of vortex from late diastole into IC is a haemodynamic measure of coupling between diastole and systole. The change in VS is correlated with LV mechanical performance and shows association with adverse clinical outcomes seen in HF patients.

Early impairment of left ventricular function in patients with systemic hypertension: new insights with 2-dimensional speckle tracking echocardiography.

BACKGROUND: Two-dimensional strain imaging allows rapid and accurate analysis of regional left ventricular (LV) principal strains in the longitudinal, radial, and circumferential directions. The aim of this study was to assess the ability of subtle differences in LV principal strains to characterize features of subclinical LV dysfunction in patients with systemic hypertension and apparently preserved LV systolic function. METHODS: 2-dimensional echocardiographic (2DE) images of the LV were acquired in apical 4-chamber and parasternal short-axis at the basal, mid, and apical levels in 59 subjects, including 25 healthy controls (33 ± 4 yrs, 14 male) and 34 patients with systemic hypertension (36 ± 3 yrs, 24 male). Longitudinal (LS), circumferential (CS) and radial strains (RS) were quantified in an 18-segment model using a novel speckle tracking system (2D Cardiac Performance Analysis, TomTec Imaging System, Munich, Germany). RESULTS: In comparison with normal controls, peak LS was markedly attenuated in the subendocardial and subepicardial regions in patients with systemic hypertension. However, circumferential strain was reduced only in subepicardial region; radial strain was not significantly different in the two groups. The subendocardial-to-subepicardial gradient of circumferential deformation correlated with the radial strains in both controls and hypertensive patients (R = 0.87, p < 0.001). CONCLUSIONS: Despite reduced longitudinal shortening, LV wall thickening in patients with systemic hypertension remains unaltered due to relatively preserved circumferential shortening. Characterizing the disparities in LV principal strains reveals the presence of subclinical LV dysfunction and provides unique insights into functional adaptations that maintain global LV ejection fraction in patients with systemic hypertension.

Left ventricular myocardial performance assessed by 2-dimensional speckle tracking echocardiography in patients with sickle cell crisis.

BACKGROUND: The status of left ventricle in sickle cell anemia presenting in sickle crisis and follow up has been minimally studied in past. To determine the left ventricular (LV) myocardial performance in these patients, we performed the study to assess two dimensional strains imaging which allowed a rapid and an accurate analysis of global and regional LV myocardial performance in longitudinal, radial, and circumferential directions. METHODS: In this prospective study, 2-dimensional echocardiography (2DE) images of the LV were obtained in 52 subjects which included 32 patients (23 ± 8yrs, 16 male) with homozygous sickle cell anemia (SCA) in sickle cell crisis and 20 healthy controls (23 ± 5 yrs, 11 male) using apical 4-chamber and parasternal short-axis at the basal, mid, and apical levels. Of these 32 patients, 2DE was performed again in 18 patients in follow up (8 months ± 5 days). Longitudinal, circumferential and radial strains (LS, CS and RS respectively) were quantified and compared in an 18-segment model using a novel speckle tracking system (2D Cardiac Performance Analysis, TomTec Imaging System, Munich, Germany). RESULTS: There was no significant difference in LV ejection fraction between both the groups (59.32 ± 12.6 vs. 52.3 ± 7.9; p-value > 0.05). In comparison with normal controls and follow up of sickle cell patients, peak LS was significantly attenuated in the subendocardial and subepicardial regions during sickle cell crisis (p < 0.05). However, a significant reduction in circumferential strain was evident only in subepicardial region (p < 0.001). Also patients in sickle cell crisis showed significantly higher radial strain parameters than controls (p < 0.001). CONCLUSION: Patients with SCA presenting in sickle cell crisis have reduced longitudinal shortening. LV myocardial performance remains unaltered due to relatively preserved circumferential shortening and increased radial thickening.

Functional strain-line pattern in the human left ventricle.

Analysis of deformations in terms of principal directions appears well suited for biological tissues that present an underlying anatomical structure of fiber arrangement. We applied this concept here to study deformation of the beating heart in vivo analyzing 30 subjects that underwent accurate three-dimensional echocardiographic recording of the left ventricle. Results show that strain develops predominantly along the principal direction with a much smaller transversal strain, indicating an underlying anisotropic, one-dimensional contractile activity. The strain-line pattern closely resembles the helical anatomical structure of the heart muscle. These findings demonstrate that cardiac contraction occurs along spatially variable paths and suggest a potential clinical significance of the principal strain concept for the assessment of mechanical cardiac function. The same concept can help in characterizing the relation between functional and anatomical properties of biological tissues, as well as fiber-reinforced engineered materials.

Pacing polarity and left ventricular mechanical activation sequence in cardiac resynchronization therapy.

OBJECTIVE: The aim of this study is to evaluate the relationship between polarity of left ventricular (LV) pacing and the resultant regional, global, and transmural mechanical sequence of contraction. BACKGROUND: Cardiac resynchronization therapy (CRT) is widely utilized in patients with drug refractory congestive heart failure with systolic dysfunction (EF <35 %) and intraventricular conduction delay (QRS duration >120 ms). However, little is known about polarity of pacing stimulation and the resultant differences in LV mechanics. METHODS: The polarity of pacing was altered sequentially in 20 patients (73 ± 13, 16 males) with preexisting biventricular devices with potential choice of multiple vectors for pacing stimulation. Initial unipolar or extended bipolar configurations were switched to bipolar configuration or vice versa, and echocardiographic images were acquired for off-line analysis. Regional and global LV longitudinal and radial mechanics were assessed selectively from the subendocardial and subepicardial regions with 2D speckle-tracking echocardiography. Left ventricular capture by each vector configuration was confirmed by local lead capture and appropriate QRS alteration. RESULTS: Unipolar pacing resulted in increased dispersion of LV regional endocardial strains with a higher base-to-apex gradients of longitudinal shortening strains (P < 0.05). LV longitudinal shortening strain magnitude was higher at LV base with bipolar stimulation in comparison with unipolar stimulation (-10.5 ± 10.5 vs. -4.2 ± 6.3, P = 0.02). CONCLUSION: There is a difference in the mechanical activation sequence of the LV between unipolar vs. bipolar pacing stimulation. This may have important implications for CRT.

Relationship of contrast-enhanced magnetic resonance imaging-derived intramural scar distribution and speckle tracking echocardiography-derived left ventricular two-dimensional strains.

AIMS: Information is limited regarding the functional correlates of intramural scar burden in myopathic hearts. We aimed to explore the use of speckle tracking echocardiography selectively at three intramural locations, to investigate the variance in cardiac strains and their relationship to contrast-enhanced magnetic resonance imaging-derived scar distribution and global left ventricular systolic function. METHODS AND RESULTS: Fifty-nine patients with evidence of myocardial fibrosis on contrast-enhanced magnetic resonance imaging and 18 healthy subjects underwent speckle tracking echocardiography for measuring subendocardial, midmyocardial, and subepicardial strains in longitudinal, circumferential, and radial directions. Patients were divided into three categories of scar distribution: Group A, endocardial and midmyocardial; Group B, midmyocardial and epicardial; and Group C, transmural. When these patients were compared with 18 healthy control subjects, longitudinal left ventricular deformation was attenuated equally for all three groups, whereas circumferential strain was relatively well preserved. On multivariate analysis, circumferential strain and scar burden were independent determinants of left ventricular ejection fraction (R(2) = 0.57; P = 0.003 for strain burden and P = 0.01 for scar burden). CONCLUSION: Longitudinal strains are attenuated independent of myocardial scar location. This alteration in left ventricular deformation is associated with circumferential mechanics becoming a key determinant of global left ventricular pump function in myopathic hearts.

Myocardial deformation and rotational mechanics in revascularized single vessel disease patients 2 years after ST-elevation myocardial infarction.

OBJECTIVE: We sought to characterize the left ventricular strains and rotational mechanics in the infarct-related and remote regions of dilated heart following an ST-elevation myocardial infarction (STEMI) to understand the adaptive changes in global left ventricular function that develop several months after percutaneous coronary revascularization. METHODS: Forty-six patients with STEMI (66.6 ± 11 years, 29 men) 2 years after coronary revascularization were enrolled. Longitudinal, circumferential, radial and rotational mechanics of the left ventricle were evaluated by speckle tracking echocardiography in 39 (84.8%) of them, after excluding seven patients with multivessel coronary disease. Forty-one asymptomatic volunteers without a history of coronary artery disease (65 ± 9 years, 23 men) served as controls. RESULTS: There was no difference, between groups, regarding the prevalence of cardiovascular risk factors, whereas patients had significantly reduced left ventricular strains (P<0.001), rotations (P<0.001), twist (P<0.001), torsion (P<0.001) and untwisting rates (P<0001) in comparison with controls. Furthermore, reduction in regional strains was observed both in infarct and remote regions of the left ventricle and correlated with the changes in ejection fraction. On logistic regression analysis, only global circumferential strain was independently related (odds ratio 4.28; 95% confidence interval 1.11-16.4; P=0.034) with left ventricular dilation, defined as an indexed end-diastolic left ventricular volume more than 75 ml/m. CONCLUSION: Reduction in regional strains and rotational mechanics are detectable in both the infarct-related and remote regions of dilated left ventricle. Attenuation of global circumferential strain, rather than isolated changes in the mechanics of the infarct region might contribute to determine the extent of left ventricular dilation, independent of the presence of multiple risk factors for left ventricular dysfunction. These findings might have important clinical implications regarding novel therapeutic approaches for counteracting left ventricular remodeling.

Global left atrial strain correlates with CHADS2 risk score in patients with atrial fibrillation.

BACKGROUND: The aim of this cross-sectional study was to explore the association between echocardiographic parameters and CHADS2 score in patients with nonvalvular atrial fibrillation (AF). METHODS: Seventy-seven subjects (36 patients with AF, 41 control subjects) underwent standard two-dimensional, Doppler, and speckle-tracking echocardiography to compute regional and global left atrial (LA) strain. RESULTS: Global longitudinal LA strain was reduced in patients with AF compared with controls (P < .001) and was a predictor of high risk for thromboembolism (CHADS2 score ≥ 2; odds ratio, 0.86; P = .02). LA strain indexes showed good interobserver and intraobserver variability. In sequential Cox models, the prediction of hospitalization and/or death was improved by addition of global LA strain and indexed LA volume to CHADS2 score (P = .003). CONCLUSIONS: LA strain is a reproducible marker of dynamic LA function and a predictor of stroke risk and cardiovascular outcomes in patients with AF.

Left atrial reservoir function predicts atrial fibrillation recurrence after catheter ablation: a two-dimensional speckle strain study.

BACKGROUND: Predictors of atrial fibrillation (AF) recurrence after catheter ablation (CA) are not fully defined. We hypothesized that 2D left atrial (LA) regional strain maps would help identify abnormal atrial substrate that increases susceptibility to AF recurrence post-CA. METHODS AND RESULTS: Sixty-three patients (63 ± 10 years, 60% male) underwent CA for symptomatic paroxysmal (75%) or persistent (25%) AF. Baseline LA mechanical function determined using speckle tracking echocardiography was compared between those with AF recurrence (AFR) and no recurrence post-CA. Bi-dimensional global and regional maps of LA wall velocity, strain, and strain rate (SR) were obtained during end ejection and early diastole. After 18 ± 12 months of follow-up, 34 patients were free of AFR post-CA. There were no differences in clinical characteristics, LA and LV volumes, and Doppler estimates of LV diastolic function and filling pressures at baseline between patients with recurrent AF and those that maintained sinus rhythm. However, the LA emptying fraction (55 ± 17% vs. 64 ± 14%, p = 0.04), global and regional systolic and diastolic strains, SR, and velocities were reduced in patients with recurrent AF. There was marked attenuation of peak LA lateral wall longitudinal strain (LS; 11 ± 7% vs. 20 ± 14%, p = 0.007) and SR (0.9 ± 0.4 vs.1.3 ± 0.6 s(-1), p = 0.01). Multivariate analysis revealed lateral wall LS (odds ratio = 1.15, 95% CI = 1.02-1.28, p = 0.01) as an independent predictor of AFR. CONCLUSIONS: Regional LA lateral wall LS is a pre-procedural determinant of AFR in patients undergoing CA, independent of LA enlargement. Characterization of atrial myocardial tissue properties by speckle tracking echo may aid the appropriate selection of adjunctive strategies and prognostication of patients undergoing CA.

Natural history of left ventricular mechanics in transplanted hearts: relationships with clinical variables and genetic expression profiles of allograft rejection.

OBJECTIVES: The aim of this study was to explore the temporal evolution of left ventricular (LV) mechanics in relation to clinical variables and genetic expression profiles implicated in cardiac allograft function. BACKGROUND: Considerable uncertainty exists regarding the range and determinants of variability in LV systolic performance in transplanted hearts (TXH). METHODS: Fifty-one patients (mean age 53 ± 12 years; 37 men) underwent serial assessment of echocardiograms, cardiac catheterization, gene expression profiles, and endomyocardial biopsy data within 2 weeks and at 3, 6, 12, and 24 months after transplantation. Two-dimensional speckle-tracking data were compared between patients with TXH and 37 controls (including 12 post-coronary artery bypass patients). Post-transplantation mortality and hospitalizations were recorded with a median follow-up period of 944 days. RESULTS: Global longitudinal strain (LS) and radial strain remained attenuated in patients with TXH at all time points (p < 0.001 and p = 0.005), independent of clinical rejection episodes. Failure to improve global LS at 3 months (≥ 1 SD) was associated with higher incidence of death and cardiac events (hazard ratio: 5.92; 95% confidence interval: 1.96 to 17.91; p = 0.049). Multivariate analysis revealed gene expression score as the only independent predictor of global LS (R(2) = 0.53, p = 0.005), with SEMA7A gene expression having the highest correlation with global LS (r = -0.84, p < 0.001). CONCLUSIONS: Speckle tracking-derived LV strains are helpful in estimating the burden of LV dysfunction in patients with TXH that evolves independent of biopsy-detected cellular rejection. Failure to improve global LS at 3 months after transplantation is associated with a higher incidence of death and cardiac events. Serial changes in LV mechanics correlate with peripheral blood gene expression profiles and may affect the clinical assessment of long-term prognosis in patients with TXH.

Non-uniform recovery of left ventricular transmural mechanics in ST-segment elevation myocardial infarction.

BACKGROUND: After a transient ischemic episode, the subendocardial region is more severely injured than outer subepicardial layers and may regain a proportionately greater degree of mechanical function in the longitudinal direction. We sought to explore left ventricular (LV) transmural mechanics in patients with ST-segment elevation myocardial infarction (STEMI) for determining the mechanism underlying recovery of global LV function after primary percutaneous coronary intervention (PCI). METHODS: A total of 42 patients (62 +/- 11 years old, 71% male) with a first STEMI underwent serial assessments of LV longitudinal, circumferential and radial strains (LS, CS and RS) by selective tracking of subendocardial and subepicardial regions within 48 hours and a median of 5 months after PCI. LV mechanical parameters were compared with sixteen age and gender matched normal controls. RESULTS: In comparison with controls, endocardial and epicardial LS were markedly attenuated at 48 hours following PCI (P < 0.001). An improvement in LV ejection fraction (EF > 5%) following PCI was seen in 24 (57%) patients and was associated with improvement in endocardial and epicardial LS (P < 0.001 and P = 0.003, respectively) and endocardial CS (P = 0.01). Radial strain and wall motion score index, however, remained persistently abnormal. The change in endocardial LS (OR 1.2, 95% CI 1.03 to 1.42, P = 0.01) and the change in epicardial LS (OR 1.2, 95% 1.03 to 1.46, P = 0.02) were significantly associated with the improvement in LVEF, independent of the location of STEMI and the presence of underlying multivessel disease. CONCLUSIONS: In patients with STEMI treated by PCI, the recovery of LV subendocardial shortening strain seen in the longitudinal direction underlies the improvement in LV global function despite persistent abnormalities in radial mechanics and wall motion score index.

Assessment of myocardial mechanics using speckle tracking echocardiography: fundamentals and clinical applications.

The authors summarize the recent developments in speckle-tracking echocardiography (STE), a relatively new technique that can be used in conjunction with two-dimensional or three-dimensional echocardiography for resolving the multidirectional components of left ventricular (LV) deformation. The tracking system is based on grayscale B-mode images and is obtained by automatic measurement of the distance between 2 pixels of an LV segment during the cardiac cycle, independent of the angle of insonation. The integration of STE with real-time cardiac ultrasound imaging overcomes some of the limitations of previous work in the field and has the potential to provide a unified framework to more accurately quantify the regional and global function of the left ventricle. STE holds promise to reduce interobserver and intraobserver variability in assessing regional LV function and to improve patient care while reducing health care costs through the early identification of subclinical disease. Following a brief overview of the approach, the authors pool the initial observations from clinical studies on the development, validation, merits, and limitations of STE.