Myocardial Deformation (myocardial + deformation)

Distribution by Scientific Domains

Selected Abstracts

Relationship between Strain Rate Imaging and Coronary Flow Reserve in Assessing Myocardial Viability after Acute Myocardial Infarction

Ph.D., Seong-Mi Park M.D.
Objectives: To evaluate the relationship between strain rate (SR) imaging and coronary flow reserve (CFR) in assessing viability of akinetic myocardium after acute myocardial infarction (MI). Methods: Forty patients with acute first ST-elevation MI were analyzed. SR imaging and CFR by intracoronary flow measurement were obtained on the same day, 3,5 days after primary percutaneous coronary intervention. Viability of the akinetic myocardium was determined on 6-week echocardiography. Results: Systolic SR (SRs, ,0.42 0.10 vs. ,0.35 0.11 per second, P = 0.03), early diastolic SR (SRe, 0.68 0.31 vs. 0.41 0.22 per second, P = 0.003), and systolic strain (Ss, ,5.9 3.4 vs. ,2.5 4.0%, P = 0.04) were greater in akinetic, but viable myocardium of 21 patients than in akinetic and nonviable myocardium of 19 patients. CFR was also higher in patients with akinetic, but viable myocardium (2.0 0.5 vs. 1.5 0.5, P < 0.001). SRs, SRe, and Ss were significantly related to CFR (r =,0.50, r = 0.58, r =,0.56, respectively, all P , 0.001) and SRe was most related to CFR (P < 0.001). The sensitivity and specificity to predict myocardial viability were 85.7% and 68.4% for CFR (cutoff = 1.75), and 90.5% and 57.9% for SRe (cutoff = 0.37 per second), respectively. Conclusions: The degree of myocardial deformation determined by SR imaging was related to the degree of microvascular integrity determined by CFR, and can be used as a noninvasive method to predict myocardial viability after acute MI. (Echocardiography 2010;27:977-984) [source]

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

F.A.S.E., Nikolaos J. Skubas M.D.
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. [source]

Altered T Wave Dynamics in a Contracting Cardiac Model

Introduction: The implications of mechanical deformation on calculated body surface potentials are investigated using a coupled biophysically based model. Methods and Results: A cellular model of cardiac excitation-contraction is embedded in an anatomically accurate two-dimensional transverse cross-section of the cardiac ventricles and human torso. Waves of activation and contraction are induced by the application of physiologically realistic boundary conditions and solving the bidomain and finite deformation equations. Body surface potentials are calculated from these activation profiles by solving Laplace's equation in the passive surrounding tissues. The effect of cardiac deformation on electrical activity, induced by contraction, is demonstrated in both single-cell and tissue models. Action potential duration is reduced by 7 msec when the single cell model is subjected to a 10% contraction ramp applied over 400 msec. In the coupled electromechanical tissue model, the T wave of the ECG is shown to occur 18 msec earlier compared to an uncoupled excitation model. To assess the relative effects of myocardial deformation on the ECG, the activation sequence and tissue deformation are separated. The coupled and uncoupled activation sequences are mapped onto the undeforming and deforming meshes, respectively. ECGs are calculated for both mappings. Conclusion: Adding mechanical contraction to a mathematical model of the heart has been shown to shift the T wave on the ECG to the left. Although deformation of the myocardium resulting from contraction reduces the T wave amplitude, cell stretch producing altered cell membrane kinetics is the major component of this temporal shift. (J Cardiovasc Electrophysiol, Vol. 14, pp. S203-S209, October 2003, Suppl.) [source]

Magnitude image CSPAMM reconstruction (MICSR)

Moriel NessAiver
Abstract Image reconstruction of tagged cardiac MR images using complementary spatial modulation of magnetization (CSPAMM) requires the subtraction of two complex datasets to remove the untagged signal. Although the resultant images typically have sharper and more persistent tags than images formed without complementary tagging pulses, handling the complex data is problematic and tag contrast still degrades significantly during diastole. This article presents a magnitude image CSPAMM reconstruction (MICSR) method that is simple to implement and produces images with improved contrast and tag persistence. The MICSR method uses only magnitude images , i.e., no complex data , but yields tags with zero mean, sinusoidal profiles. A trinary display of MICSR images emphasizes their long tag persistence and demonstrates a novel way to visualize myocardial deformation. MICSR contrast and contrast-to-noise ratios (CNR) were evaluated using simulations, a phantom, and two normal volunteers. Tag contrast 1000 msec after the R wave trigger was 3.0 times better with MICSR than with traditional CSPAMM reconstruction techniques, while CNRs were 2.0 times better. Magn Reson Med 50:331,342, 2003. 2003 Wiley-Liss, Inc. [source]