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Background: In idiopathic dilated cardiomyopathy (IDC), myocardial deformational parameters and their mutual relationships remain incompletely characterized., Methods: Thirty-seven patients with IDC underwent two-dimensional speckle-tracking echocardiography (2D-STE) to assess left ventricular rotation, torsion, and longitudinal, circumferential, and radial systolic and diastolic strains and strain rates. Additionally, 2D-STE was performed in 14 controls., Results: All deformational parameters on 2D-STE were significantly lower in patients with IDC compared with controls. Seven patients exhibited opposite basal (positive, counterclockwise) and 11 patients exhibited opposite apical (negative, clockwise) rotation at end-systole. Circumferential, radial, and longitudinal early diastolic strain rates were correlated most strongly with the corresponding spatial components of systolic deformation., Conclusion: In patients IDC, all torsional, systolic, and diastolic deformational parameters were decreased. Corresponding three-dimensional components of systolic and diastolic deformations were closely coupled. Considerable variation in the direction of basal and apical rotation exists in a subset of patients with IDC.

Background: Capitalizing on mechanoenergetic coupling, we investigated whether strain echocardiography can noninvasively estimate the ratio of adenosine triphosphate (ATP) to adenosine diphosphate (ADP), a marker of energetic status during acute myocardial ischemia and reperfusion., Methods: Twenty-eight pigs were divided into 7 groups (1 baseline, 4 ischemic, and 2 reperfusion). Ischemia was induced by left anterior descending coronary artery occlusion. Longitudinal systolic lengthening (SL) and postsystolic shortening (PSS) strain were measured by echocardiography. The ATP/ADP ratio was obtained from myocardial biopsies in the ischemic and control regions., Results: SL and PSS strain and the ATP/ADP ratio progressively decreased (P < .05) with increased duration (12, 40, 120, and 200 minutes) of ischemia. A mathematical formula (ATP/ADP = -0.97 + 0.25 x PSS strain + 0.20 x SL strain) estimated best the ATP/ADP ratio (r = 0.94, P < .05). Reperfusion after 12 but not after 120 minutes of ischemia significantly improved the ATP/ADP ratio and decreased SL and PSS strain., Conclusions: Strain echocardiography closely reflected changes and enabled the noninvasive estimation of the ATP/ADP ratio. A higher ATP/ADP ratio is associated with functional improvement after reperfusion.

Background: Sonomicrometry is a gold standard in experimental studies on myocardial motion. However, limited information exists regarding mechanical and biochemical changes produced by sonomicrometry crystal (SC) insertion into the myocardial wall., Methods: In 10 open-chest pigs, we implanted SCs into the inner half of apical anterior and midposterior regions. Longitudinal strains (systolic lengthening, end-systolic, peak shortening, and postsystolic shortening strains) and strain rate (SR) measurements (peak systolic ejection and early and late diastolic SRs) were obtained by Doppler SR echocardiography along with troponin I levels measured from peripheral blood before and after SC insertion., Results: SR and strain parameters did not change significantly after SC implantation. Troponin I levels increased significantly from less than 0.010 to 0.129 +/- 0.138 microg/L (P < .005) after SC implantation., Conclusions: Our study demonstrates that despite biochemical evidence of myocardial injury, carefully implanted SCs do not alter systolic or diastolic regional myocardial function assessed by Doppler echocardiography.

Doppler tissue imaging (DTI) and DTI-derived strain imaging are robust physiologic tools used for the noninvasive assessment of regional myocardial function. As a result of high temporal and spatial resolution, regional function can be assessed for each phase of the cardiac cycle and within the transmural layers of the myocardial wall. Newer techniques that measure myocardial motion by speckle tracking in gray-scale images have overcome the angle dependence of DTI strain, allowing for measurement of 2-dimensional strain and cardiac rotation. DTI, DTI strain, and speckle tracking may provide unique information that deciphers the deformation sequence of complexly oriented myofibers in the left ventricular wall. The data are, however, limited. This review examines the structure and function of the left ventricle relative to the potential clinical application of DTI and speckle tracking in assessing the global mechanical sequence of the left ventricle in vivo.

Background: We previously found that a 2-dimensional (2D) strain echocardiography method had some limitations in the assessment of low magnitudes and rates of deformation. Here, we study whether a recently introduced high spatial resolution speckle tracking (HRT) method improves accuracy of 2D strain measurements., Methods: A gelatin block was cyclically compressed by a hydraulic piston. Regional deformations measured by 2D-HRT were compared with reference strains obtained from an embedded pair of sonomicrometry crystals. Global deformations (along the gelatin block) were compared to strains calculated from tracings of piston motion. We tested a wide range of strains (5.4%-21.5%) and combined each measurement with simulated heart rates (24-196/min)., Results: Regional deformations measured by 2D-HRT demonstrated excellent correlation (r = 0.99, P < .0001) and agreement (bias +/- 2SD = -0.3 +/- 1.3%) with sonomicrometry. Close correlation (r = 0.99, P < .0001) and agreement (bias +/- 2SD = 0.5 +/- 1.2%) was observed also for global strains measured by 2D-HRT and compared with tracings of piston motion. There was good reproducibility of all tests: interobserver and intraobserver variabilities were 3.2% and 3.4% for regional strains and 3.1% and 3.5% for global strains, respectively., Conclusion: In our in vitro setting, the 2D-HRT method produced precise and accurate measurements of strains for clinically relevant ranges of deformation magnitudes and ranges.

Background: Myocardial function is transmurally heterogeneous. Postsystolic work may functionally reflect ischemic but viable myocardium. We calculated systolic and postsystolic regional myocardial work index (RMWi) in subendocardial and subepicardial layers of myocardium supplied by a slowly occluding coronary artery., Methods: Progressive stenosis of the left anterior descending coronary artery lasting 11 +/- 5 days (end point) was induced in 10 dogs, and pressure-strain loops were obtained from subendocardial and subepicardial layers of apical and middle anterior segments by intracardiac ultrasound., Results: At baseline, the RMWi was significantly higher (P < .05) in the subendocardial layer. At the end point, there was no significant change in the RMWi in ischemic myocardium; however, the postsystolic RMWi was higher (P < .05) in the subendocardial layer and accompanied a decrease in subendocardial myocardial blood flow, although viability was largely maintained., Conclusion: A significant subendocardial postsystolic RMWi at rest suggests an impending ischemic injury in coronary artery disease when segmental function is still preserved.

Introduction: Doppler tissue imaging is a new technology for quantitative evaluation of myocardial motion and contractility, and is available in several ultrasound systems. This study evaluates the comparability, accuracy, and reproducibility of measurements of velocity, strain rate, and strain by two high-end ultrasound systems., Methods: Accuracy was assessed by imaging a tissue-mimicking gelatin phantom, and the comparability of measurements in the right ventricular free wall and interventricular septum was assessed in 20 healthy participants. Reproducibility was evaluated by repeated recordings in vitro and in a random subset of patients., Results: In vitro, a high degree of accuracy was found in both systems, with one system measuring slightly lower values than the reference values (mean difference 0.35 +/- 0.18 cm/s, P < .001). Values higher than the reference values were measured by both systems for strain and strain rate. In vivo, no systematic differences in measured velocities, strain rate, and strain were found; however, wide limits of agreement were seen for strain and strain rate. Measurements of tissue velocity, strain, and strain rate were well reproducible, nevertheless wide variation was found in both systems (coefficient of variation = 9%-19%)., Conclusion: For clinical purposes, both systems have sufficient accuracy for measurements of tissue velocity. The variation in measurements of strain rate and strain by Doppler tissue imaging should be taken into account when designing studies using this new technology. Approaches to potentially reduce this variation should be addressed in future studies.

Background: A new 2-dimensional strain echocardiography (2DSE) method has been introduced that measures myocardial deformations by tracking localized acoustic markers. We compared strains measured in vitro and in vivo by 2DSE with those obtained by sonomicrometry., Methods: For the in vitro study, a tissue-mimicking gelatin block was cyclically compressed and longitudinal strains obtained by 2DSE and sonomicrometry crystals. For the in vivo study, arrays of crystals were implanted into the apical anteroseptal (test region) and midposterior (control region) in 16 open-chest pigs and strains measured by 2DSE and crystals at baseline and after acute ischemia., Results: In vitro, pooled data demonstrated good correlation (r = 0.99, P < .0001) and close agreement (bias +/- 2SD = 0.7 +/- 2.2%) of 2DSE and sonomicrometry. For a combination of low testing strains (5.4%) and strain rates (0.8 and 1.2 Hz), 2DSE overestimated strains by sonomicrometry. In vivo, linear regression analysis of pooled measurements demonstrated again a good correlation (r = 0.94, P < .0001) and agreement (1.1 +/- 7.5%) of 2DSE with sonomicrometry with a trend toward lower absolute values of strains by 2DSE., Conclusion: The 2DSE demonstrated good overall correlation and agreement with sonomicrometry for the tested in vitro and in vivo values. Some caution with 2DSE measurements is needed for combinations of low strains and strain rates.

Background: We aimed to assess whether myocardial postsystolic thickening (PST) can be induced by an acute increase in right ventricular (RV) afterload and, thus, demonstrate that PST may have a nonischemic cause., Methods: In 8 anesthetized open-chest pigs, radial strains of the interventricular septum (IVS) and left ventricular inferolateral wall were obtained by Doppler tissue echocardiography before and during constriction of the pulmonary artery., Results: After each constriction, RV peak systolic pressure increased from 30 +/- 5 to 57 +/- 8 mm Hg (P < .001). Peak systolic radial strain of the IVS decreased from 20.8% +/- 5.3% to 9.5% +/- 4.1% (P = .003), and PST of the IVS increased from 0.3% +/- 0.5% to 6.1% +/- 4.8% (P = .01). The onset of PST started 41 +/- 20 milliseconds after peak negative dP/dt of RV pressure. The inferolateral wall did not show PST., Conclusion: An acute increase in RV pressure causes a significant reduction in peak systolic strain of the IVS associated with the nonischemic appearance of PST.

Background: Ischemia is primarily a metabolic event. However, regional functional changes can be affected by structural alterations. We developed an experimental model of sole myocardial energy metabolism inhibition and characterized the resulting regional dysfunction., Methods: In 12 pigs, we regionally inhibited creatine kinase (CK) and, consequently, myocyte high-energy phosphate transfer by intracoronary administration of iodoacetamide. Myocardial biopsies for CK activity and structural analyses and strain rate (SR) echocardiography scans were obtained at baseline and 60 minutes after iodoacetamide administration. Plasma levels of the CK isoenzyme MB and troponin I were assessed to determine possible myocardial damage., Results: CK activity in the iodoacetamide-perfused myocardium decreased to 0.5% of the original value and was accompanied by a reduction in peak systolic SR ( P < .0001), end-systolic strain ( P < .0001), and peak SRs of myocardial early and late filling waves ( P < .0001). Microscopy showed contracture without sarcomere disruption. Plasma levels of CK isoenzyme MB and troponin I did not change., Conclusions: Regional inhibition of myocyte energetics leads to both systolic and diastolic dysfunction by SR echocardiography, but the presence of a residual phosphotransfer protects microstructural integrity.