For the last decade aortic intramural hematoma (AIH), a variant form of classic aortic dissection (AD), has emerged as an increasingly recognized and potentially fatal entity of acute aortic syndrome (AAS). The successful clinical introduction of noninvasive imaging modalities for aortic diseases, including transesophageal echocardiography (TEE), has contributed to early differential diagnosis of AIH and investigation of its natural course or remodeling process after the initial event. AIH, which is characterized by circular or crescentic aortic wall thickening without an intimal flap or tear, is easily differentiated from classic AD. Other findings suggestive of AIH are smooth contour of the aortic lumen, increased density of aortic wall thickening before contrast injection, and demonstration of an 'echo-lucent area' or 'echo-free space' within the thickened aortic wall. It is widely accepted that AIH is not just a precursor of AD but has diverse remodeling processes, and, compared to classic AD, has a more favorable clinical course including complete resorption with medical treatment, reported even in type A pathology. Further study has demonstrated that two important predictors for the development of AD or mortality are aortic diameter and hematoma thickness. Thus, noninvasive imaging modalities are useful not only for diagnosis but also for risk stratification and treatment strategy selection. Although a consensus regarding optimal management strategies, especially for type A AIH, has not been established, this is in part due to our incomplete understanding of AIH. With more information of this interesting disease entity, the role of TEE and other noninvasive imaging modalities is expected to be reestablished in the near future.
Background. Three-dimensional (3D) echocardiography (3DE) has demonstrated superior accuracy and reproducibility over conventional 2DE for measuring left ventricular (LV) volumes. This study evaluates the clinical feasibility of 3DE for assessing regional LV function by measuring segmental volumes and segmental ejection fraction (EF). Methods. Freehand 3DE was performed in 9 subjects using an electromagnetic tracking device. The image acquisition was obtained by manually rotating the probe into the apical position. After automated border detection and computation were performed, a reconstructed 4D (3D + time) image of LV with 16 divided LV segments was obtained. Global and segmental volume changes with time were plotted as a time-volume curve. Reference values of segmental wall motion parameter and segmental EF were calculated from 6 healthy subjects and were used for comparison with corresponding values of patients with wall-motion abnormalities. Z scores (the units of SD from the normal reference) converted from the segmental EF were also used for comparison. Results. In normal subjects, segmental end-diastolic volume (EDV) ranged from 2.2 to 8.8 mL (5.1±1.8 mL), and segmental end-systolic volume (ESV) ranged from 0.4 to 4.6 mL (1.7±0.8 mL); segmental stroke volume (SV) ranged from 1.4 to 7.1 mL (3.4±1.3 mL), and segmental EF ranged from 46 to 88 % (67±11 %). In a patient with anterior myocardial infarction (MI), the segmental EDV and ESV of the anterior wall are much larger than other segments (anterior basal segment: 17.7 and 17.5 mL, mid-segment: 16.6 and 15.6 mL, respectively). In a patient with inferior MI, segmental SV was <1.0 mL and EF was <40 % in the inferior and inferoseptal segments. In a patient with dilated cardiomyopathy, the segmental EF ranged from 13 to 34% (20.6±5.9%) and all Z scores were <-2. Conclusions. The present study introduces new parameters of regional LV function that might help to evaluate patients with LV wall motion abnormalities.
Background. Myocardial perfusion can be quantified using the replenishment curve of the myocardial opacification derived after transient high power ultrasound exposure (burst) in real-time myocardial contrast echocardiography (MCE). However, the effect of acoustic power of burst for bubble destruction may confound results. Thus, the goal of the present study was to examine the effect of burst intensity on the parameters of the replenishment curve. Methods. Myocardial opacification of the left ventricular short-axis view was observed using SIEMENS Sequoia 512 (mechanical index = 0.1) during infusion of Definity in eight open-chest dogs. The mechanical index (MI) of burst was set as high and low (0 and -11dB), and the regions of interest were placed on the anterior and lateral walls of the left ventricle. The temporal changes in video intensity of the end-diastolic phase after the burst procedure were fitted to an exponential function: y=a(1-e-βt)+c. The plateau video intensity was defined as the A-value which was calculated as the sum of the a and c values. Results. The A-value remained constant with changes in the burst MI. Although the video intensity after the high intensity (0dB) burst was similar to that of the baseline, the video intensity after the low intensity (-11dB) burst was significantly higher than that of the baseline (anterior: 5.5±2.2 dB at baseline vs. 7.4±2.4 dB at -11dB burst; lateral: 5.9±2.5 dB at baseline vs. 9.3±3.2 dB at -11dB burst), which suggests that low MI burst results in incomplete bubble destruction. Furthermore, the β-value increased as the burst MI decreased (anterior: 0.39±0.07 and 0.54±0.15; lateral: 0.27±0.05 and 0.39±0.12 in response to a burst MI of 0 and -11dB, respectively). Conclusions. The myocardial microbubble velocity (β-value) derived from the replenishment curve by using bubble destruction technique in real-time MCE is overestimated when bubble destruction is incomplete.
Background. A novel tissue-tracking system (TTS) that enables automatic assessment of two-dimensional (2-D) strain of left ventricle (LV) segments simultaneously from gray-scale digital echocardiography images has been validated in an animal study at our institution. We sought to define the application of TTS for automatic quantification of systolic wall thickening (WT) with a study in humans. Methods. We assessed 202 LV segments from 101 good and fair quality digital echo images acquired from 35 subjects. Radial strain was automatically derived from displacement between two points of interest placed at the epi- and endocardial borders of each segment. Peak radial strain at each segment was compared with manually measured systolic wall thickening. Results. There were good correlation and agreement between 2-D radial strain assessed by TTS and manually measured systolic WT in overall subjects (r = 0.89, p < 0.001). The correlation and agreements were better in good quality images (r = 0.94, p < 0.001) rather than that in fair quality images (r = 0.82, p < 0.001). Conclusion. The novel TTS provides a method for automatic quantification of human LV systolic wall thickening.
Background. The aim of this study was to discriminate ischemic cardiomyopathy (ICM) from dilated cardiomyopathy (DCM) based on inter-segmental and transmural differences in ultrasonic tissue characters. Methods. The study population consisted of 40 patients with DCM and 40 patients with ICM with ejection fraction of <40%. We recorded short-axis integrated backscatter (IBS) images in each patient. We measured the absolute differences in average IBS values between the anterior septum and posterior wall (|A-P|, dB). We also measured the difference of average IBS in the inner layer minus that in the outer layer in either anterior septum or posterior wall that was more dysfunctional (In-Out, dB). Results. |A-P| was significantly higher in ICM than DCM (5.3 ± 1.7 vs. 2.7 ± 1.4, p<0.001). Receiver-operating characteristic analysis demonstrated that we can differentiate ICM from DCM with sensitivity of 80 % and specificity of 73 % using |A-P| > 4 dB as a cut-off point. (In-Out) was also significantly higher in ICM than DCM (1.6 ± 1.4 vs. -0.9 ± 1.9, p<0.001). We can also differentiate ICM from DCM with sensitivity of 93 % and specificity of 70 % using (In-Out) >0 dB as a cut-off point. Additionally, all patients with |A-P| > 3 dB and (In-Out) >0 dB belonged to the ICM group except for one patient. Conclusions. Inter-segmental and transmural differences in myocardial IBS are significantly greater in the ICM than in DCM. Using these particular ultrasonic tissue characters, we can discriminate ICM from DCM with favorable sensitivity and specificity.
Isolated noncompaction of the left ventricular myocardium (INVM) is associated with a high incidence of heart failure. However, it is difficult to determine accurately left ventricular (LV) systolic function because of the trabeculated ventricles. The purpose of this study was to clarify whether strain imaging could detect regional myocardial systolic function in 2 patients with INVM. We recorded myocardial strain profiles at the basal, mid-, and apical portions of the LV free wall and ventricular septum (VS) in the apical LV long-axis view. Case 1 (15-year-old male) was referred to our hospital because of ECG abnormalities. Case 2 (83-year-old female) was admitted to our hospital for congestive heart failure. Two-dimensional echocardiography in both patients showed numerous prominent trabeculations and deep intertrabecular recesses at the apex of the LV wall. Because of the trabeculations, it was difficult to determine accurately LV ejection fraction by 2-dimensional echocardiography. The percent fractional shortening of the LV (%FS) in both cases was within a normal range. However, the peak systolic strains at the apical, mid-, and basal portions of the LV free wall were lower in Case 2 (-12, -12, and -11%, respectively) than in Case 1 (-33, -37, and -37%, respectively). The peak systolic strains at the apical, mid-, and basal portions of the VS were also lower in Case 2 (-11, -16, and -11%, respectively) than in Case 1 (-27, -27, and -29%, respectively). We conclude that strain measurements are useful for evaluating regional myocardial systolic function in patients with INVM.
We report a case with perforated mitral valve aneurysm in the anterior leaflet associated with lateral scallop prolapse. Transesophageal echocardiography (TEE) revealed an apparent prolapse of the lateral segment of the mitral leaflet with mitral regurgitation and a perforated aneurysm in the anterior leaflet of the mitral valve. In this patient, an eccentric regurgitant jet toward the anterior leaflet due to lateral scallop prolapse caused structural weakening and then the aneurysm in the anterior leaflet.
Discrete subaortic stenosis is a rare condition to cause left ventricular outflow obstruction. It is sometimes difficult to diagnose it because conventional transthoracic echocardiography may fail to show its 3-dimensional feature. We document the feasibility of on-line 3-dimensional transthoracic echocardiography, by which we can obtain the important 3-dimensional structural and dynamic information of discrete subaortic stenosis.
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