Non-transmural infarction results in greater functional impairment of the endocardial than of the epicardial myocardial layer. In transmural infarction both layers are affected similarly compared with controls. A layer-specific analysis of myocardial deformation allows accurate discrimination between different transmurality categories of myocardial infarction.
Background: Definition of the optimal left ventricular (LV) lead position in cardiac resynchronisation therapy (CRT) is desirable. Objective: To define the optimal LV lead position in CRT and assess the effectiveness of CRT depending on the LV lead position using new myocardial deformation imaging. Methods: Myocardial deformation imaging based on tracking of acoustic tissue pixels in two-dimensional echocardiographic images (EchoPAC, GE ultrasound) was performed in 47 patients with heart failure at baseline and during CRT. In a 36-segment LV model the segment with the latest peak systolic circumferential strain before CRT was determined. The segment with maximal temporal difference in peak systolic circumferential strain on CRT compared with before CRT was assumed to be the LV lead position. The optimal LV lead position was defined as concurrence or immediate neighbouring of the segment with the latest contraction before CRT and those with assumed LV lead location. Results: 25 patients had optimal and 22 non-optimal LV lead positions. Before CRT, the LV ejection fraction (EF) and peak oxygen consumption (VO 2 max) were similar in patients with optimal and non-optimal LV lead positions (mean (SD) EF = 31.4 (6.1)% vs 30.3 (6.5)% and VO 2 max = 14.2 (1.8) vs 14.0 (2.1) ml/min/kg, respectively). At 3 months on CRT, EF increased by 9 (2)% vs 5 (3)% and VO 2 max by 2.0 (0.8) vs 1.1 (0.5) ml/min/kg in the optimal vs non-optimal LV lead position groups, respectively (both p,0.001). Conclusions: Concordance of the LV lead site and location of the latest systolic contraction before CRT results in greater improvement in EF and cardiopulmonary workload than the non-optimal LV lead position.
Myocardial deformation imaging based on frame-to-frame tracking of acoustic markers in 2-dimensional echocardiographic images is a powerful novel modality to identify reversible myocardial dysfunction.
Background-Strain-encoded imaging (SENC) is a new technique for myocardial deformation analysis in cardiac MRI.The aim of the study was, therefore, to evaluate whether myocardial deformation imaging performed by SENC allows for quantification of regional left ventricular function and is related to transmurality states of infarcted tissue in patients with acute myocardial infarction. Methods and Results-Cardiac MRI was performed in 38 patients with acute myocardial infarction 3Ϯ1 days after successful reperfusion using a clinical 1.5-T MRI scanner. Ten healthy volunteers served as controls. SENC is a technique that directly measures peak circumferential strain from long-axis views and peak longitudinal strain from short-axis views. Measurements were obtained for each segment in a modified 17-segment model. Wall motion and infarcted tissue were evaluated semiquantitatively from steady-state free-precession cine sequences and contrastenhanced MR images and were then related to myocardial strain. Comparison of peak circumferential strain assessed by SENC and MR tagging was performed. In total, 456 segments were analyzed. Peak circumferential and longitudinal strain calculated from SENC images was significantly different in regions defined as normokinetic, hypokinetic, or akinetic (PϽ0.001). A cutoff peak systolic circumferential strain value of Ϫ10% differentiated nontransmural from transmural infarcted myocardium, with a sensitivity of 97% and a specificity of 94%. Strain analysis of SENC and MR tagging correlated well (rϭ0.76) with narrow limits of agreement (Ϫ9.9% to 8.5%).
Conclusions-SENC
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