Nozomi Watanabe

Assessment of Coronary Arterial Thrombus by Optical Coherence Tomography

We analyzed optical coherence tomographic (OCT) characteristics of different types of coronary thrombi that had been confirmed at postmortem histologic examination. We examined 108 coronary arterial segments of 40 consecutive human cadavers. OCT images of red and white thrombi were obtained and the intensity property of these thrombi was analyzed. Red and white thrombi were found in 16 (17%) and 19 (18%) of the 108 arterial segments, respectively. Red thrombi were identified as high-backscattering protrusions inside the lumen of the artery, with signal-free shadowing in the OCT image. White thrombi were identified as low-backscattering projections in the OCT image. There were no significant differences in peak intensity of OCT signal between red and white thrombi (130+/-18 vs 145+/-34, p=0.12). However, the 1/2 attenuation width of the signal intensity curve, which was defined as the distance from peak intensity to its 1/2 intensity, was significantly different between red and white thrombi (324+/-50 vs 183+/- 42 microm, p<0.0001). A cut-off value of 250 microm in the 1/2 width of signal intensity attenuation can differentiate white from red thrombi with a sensitivity of 90% and specificity of 88%. We present the first detailed description of the characteristics of different types of coronary thrombi in OCT images. Optical coherence tomography may allow us not only to estimate plaque morphology but also to distinguish red from white thrombi.

Comprehensive Evaluation of Left Ventricular Strain Using Speckle Tracking Echocardiography in Normal Adults: Comparison of Three-Dimensional and Two-Dimensional Approaches

OBJECTIVE The two-dimensional speckle tracking (2DT) method is based on the measurements of strain on two-dimensional (2D) images, ignoring actual three-dimensional (3D) myocardial movements. We sought to investigate the feasibility of the newly developed three-dimensional speckle tracking (3DT) method to assess longitudinal, circumferential, and radial strain values, and then compared the data with those measured by 2DT. METHODS Echocardiographic examinations were performed in 46 volunteers. In the apical 3D volumetric images, 3 vectors of the strains were analyzed in 16 myocardial segments. 2D longitudinal strain was assessed in apical 4-, 3-, and 2-chamber views, and circumferential and radial strains were measured in parasternal short-axis view. RESULTS The average time for 3D image acquisition and 3D strain analysis by 3DT was significantly shorter than for 2DT. Longitudinal strain value by 3DT was significantly smaller than by 2DT (-17.4% +/- 5.0% vs -19.9% +/- 6.7%, P < .0001), and circumferential strain value by 3DT was significantly larger than by 2DT (-30.1% +/- 7.1% vs -26.3% +/- 6.9%, P < .0001). Intraobserver and interobserver variabilities were 10.1% and 10.9% in 3DT, and 9.9% and 11.1% in 2DT, respectively. CONCLUSION 3DT is a simple, feasible, and reproducible method to measure longitudinal, circumferential, and radial strains. The discordant results between 3DT and 2DT may be explained by the 3D cardiac motion that has been ignored in current 2DT.

Mitral annulus flattens in ischemic mitral regurgitation: geometric differences between inferior and anterior myocardial infarction: a real-time 3-dimensional echocardiographic study.

Background—New surgical strategies to restore the saddle shape of the mitral annulus are expected to increase annuloplasty effectiveness. Preoperative and postoperative configuration of the curved annulus, however, is difficult to quantify with 2-dimensional echocardiography. We sought to investigate the geometric deformity in the mitral annulus in ischemic mitral regurgitation (MR), comparing inferior and anterior myocardial infarction (MI) with the use of a custom quantitation software system with transthoracic 3-dimensional echocardiography. Methods and Results—We performed real-time 3-dimensional echocardiography in 23 patients with ischemic MR attributable to inferior MI or anterior MI and in 10 controls. Three-dimensional data were cropped into 18 radial planes, and we manually marked the annulus in mid systole. Three-dimensional annular images were reconstructed, and annular circumferences, areas, and heights were quantified. Annulus was significantly more dilated and flattened in ischemic MR than in controls and was further deformed in anterior MI as compared with inferior MI (control: circumference 9.9±0.7 cm, area 9.6±0.5 cm2, height 5.0±0.7 mm; inferior MI: circumference 11.5±1.2 cm [P<0.01 compared with control], area 11.4±2.0 cm2 [P<0.05 compared with control], height 3.5±1.6 mm [P<0.05 compared with control]; anterior MI: circumference 14.2±2.4 cm [P<0.0001 compared with control, P<0.05 compared with inferior MI], area 13.7±2.8 cm2 ]P<0.01 compared with control, P<0.05 compared with inferior MI], height 1.7±1.5 mm [P<0.0001 compared with control, P<0.05 compared with inferior MI]). Conclusions—Mitral annulus flattens in ischemic MR. Deformity of the mitral annulus was greater in anterior MI group than in the inferior MI group.

Assessment of the coronary calcification by optical coherence tomography

AIMS Optical coherence tomography (OCT) can delineate calcified plaque without artefacts. The aim of this study was to evaluate the ability of OCT to quantify calcified plaque in ex vivo human coronary arteries. METHODS AND RESULTS Ninety-one coronary segments from 33 consecutive human cadavers were examined. By intravascular ultrasound (IVUS), 32 superficial calcified plaques, defined as the leading edge of the acoustic shadowing appears within the most shallow 50% of the plaque plus media thickness, were selected and compared with corresponding OCT and histological examinations. The area of calcification was measured by planimetry. IVUS significantly underestimated the area of calcification compared with histological examination (y = 0.39x + 0.14, r = 0.78, p < 0.001). Although OCT slightly underestimated the area of calcification (y = 0.67x + 0.53, r = 0.84, p < 0.001), it showed a better correlation with histological examination than IVUS. CONCLUSIONS Both OCT and IVUS underestimated the area of calcification, but OCT estimates of the area of calcification were more accurate than those estimated by IVUS. Thus, OCT may be a more useful clinical tool to quantify calcified plaque.

Noninvasive detection of total occlusion of the left anterior descending coronary artery with transthoracic doppler echocardiography

OBJECTIVES The purpose of this study was to evaluate the value of transthoracic Doppler echocardiography (TTDE) for the noninvasive detection of total left anterior descending coronary artery (LAD) occlusion. BACKGROUND Total coronary occlusion is associated with an adverse long-term prognosis, and mechanical revascularization may be required for the patient with total coronary occlusion. However, a noninvasive diagnosis of total coronary occlusion before coronary angiography (CAG) has been difficult, especially in patients without clinical signs. METHODS We studied 103 consecutive patients who underwent CAG for the evaluation of coronary artery disease. The study group consisted of 16 patients with total LAD occlusion (group A) and 87 patients without total LAD occlusion (group B). Coronary flow velocity in the mid-portion of the LAD was recorded by TTDE. RESULTS Adequate spectral Doppler recordings of diastolic flow in the LAD were obtained in 98 study patients (95%; 15 patients in group A and 83 patients in group B). In group A, retrograde LAD flow was obtained in 14 (93%) of 15 patients. The mean diastolic velocity of the retrograde flow was 21.0 +/- 6.1 cm/s. In group B, antegrade LAD flow was obtained in all 83 patients (100%). The mean diastolic velocity of the antegrade flow was 21.5 +/- 7.1 cm/s. Retrograde LAD flow by TTDE had a sensitivity of 93% and a specificity of 100% for the detection of total LAD occlusion. CONCLUSIONS Retrograde flow in the LAD by TTDE is a highly sensitive and specific finding that can be used to noninvasively diagnose total LAD occlusion.

Age- and Gender-Dependency of Left Ventricular Geometry Assessed with Real-Time Three-Dimensional Transthoracic Echocardiography

BACKGROUND Aging and gender may affect left ventricular (LV) mechanics. The aim of this study was to determine the age and gender dependency of LV mechanical indices obtained from real-time three-dimensional echocardiography (RT3DE). METHODS RT3DE was performed in 280 healthy subjects (age range, 1-88 years; 137 men). From full-volume data sets, LV endocardial and epicardial borders were semiautomatically traced using quantitative software. LV volumes and corresponding long-axis diameter were measured throughout the cardiac cycle. Sphericity index was defined as the ratio of LV volume and spherical volume, calculated as 4/3 × π × (long-axis diameter/2)(3). LV mass was calculated as (LV epicardial volume - LV endocardial volume) × 1.05. The ratio of LV mass to LV volume was also calculated. RESULTS The mean value of LV ejection fraction did not change with age. However, LV volumes, mass, sphericity index, and LV mass/volume ratio were altered by age: (1) sphericity index was highest in the first decade of age and then declined until the fifth decade, (2) LV mass/volume ratio significantly increased in older age, and (3) LV mass/volume ratio was significantly higher in aged women compared with age-matched men. CONCLUSIONS Age has heterogeneous effects on LV shape and LV mass/volume ratio, potentially due to the growing process of myocardial fibers and the surrounding architecture in the younger population, as well as the aging process, with an increase in vascular stiffness and a loss of myocytes in older populations. Higher LV mass/volume ratios in older women might be a contributor to the preferential development of diastolic heart failure in this population.

Influence of chronic tethering of the mitral valve on mitral leaflet size and coaptation in functional mitral regurgitation.

OBJECTIVES The purposes of this study were to examine whether tethering of the mitral leaflets affects coaptation in patients with functional mitral regurgitation (FMR) and to assess the interaction between the mitral coaptation and mitral regurgitation severity. BACKGROUND Functional mitral regurgitation causes restriction of leaflet closure as a result of enhanced tethering of the mitral leaflets and papillary muscle (PM) displacement. METHODS Three-dimensional transesophageal echocardiography was performed in 44 patients with FMR related to the bilateral PM displacement and in 56 controls. The distance between the tip of the anterior or posterior PM and the intervalvular fibrosa were measured as the lateral or medial tethering length (TL) in midsystole. To evaluate the degree of coaptation, coaptation length (CL) at medial, middle, and lateral sites of mitral valve and an estimate of coaptation area (CA) were measured. RESULTS The FMR group showed the significantly decreased CA (1.3 ± 0.4 cm(2) vs. 1.6 ± 0.4 cm(2), p = 0.005) and CL (medial 3.2 ± 0.9 mm vs. 4.8 ± 0.6 mm, middle 3.8 ± 1.3 mm vs. 5.8 ± 0.7 mm, lateral 3.3 ± 0.9 mm vs. 4.8 ± 0.6 mm; all p < 0.0001) compared with the controls. Each CL correlated negatively and significantly with both medial and lateral TL (all p < 0.0001). Annular area (p = 0.004) was significantly smaller and leaflet-to-annular area ratio (p < 0.0001) was significantly larger in patients with nonsignificant FMR than in the patients with significant (moderate to severe) FMR. Significant correlations were found between effective regurgitant orifice area and CA or each CL (all p < 0.0001). CONCLUSIONS Coaptation decreased significantly in patients with FMR. The CL at each region was related to PM displacement and the indexes of coaptation were associated with mitral regurgitation severity.

Real-Time 3-Dimensional Echocardiographic Assessment of Left Ventricular Dyssynchrony Pitfalls in Patients With Dilated Cardiomyopathy

OBJECTIVES This study sought to establish normal values for real-time 3-dimensional echocardiography (RT3DE)-derived left ventricular (LV) dyssynchrony index (LVDI) and determine its age dependency, and to compare dyssynchrony in patients with normal LV function and patients with dilated cardiomyopathy (DCM), with and without left bundle branch block (LBBB). BACKGROUND Cardiac resynchronization therapy is known to be ineffective in one-third of patients with heart failure, highlighting the need for alternative techniques to assess LV dyssynchrony. METHODS Datasets from RT3DE were analyzed to calculate LVDI using 16- and 17-segment models. First, 135 normal subjects were studied to establish LVDI abnormality threshold (mean + 2 SD) and to study the relationship with age. Then, 3 groups of patients (N = 16 each: DCM with and without LBBB, normal LV function with LBBB) were compared with 50 age-matched normal control subjects. RESULTS In normal subjects, the 16-segment model resulted in a lower LVDI abnormality threshold than the 17-segment model (4.0% vs. 4.5%). In patients with normal LV function, LVDI was significantly lower than in those with DCM, irrespective of LBBB. Although LBBB resulted in a nearly 2-fold increase in LVDI in patients with normal LV function, its effects were nonsignificant in DCM. All patients with DCM and ejection fraction <35% had abnormally high LVDI, likely as a result of low signal-to-noise ratio in low-amplitude regional volume curves hampering accurate determination of regional ejection time. CONCLUSIONS Normal values established in this study resulted in indiscriminate diagnosis of abnormal dyssynchrony in all patients with reduced LV function. The value of RT3DE-derived LVDI in the evaluation of dyssynchrony in patients with reduced LV function needs to be critically reassessed because of the inability to accurately detect end-ejection in low-amplitude regional volume curves. Alternative indices of dyssynchrony need to be developed to address this limitation.

Prognosis of Retrograde Dissection From the Descending to the Ascending Aorta

Background—Natural history of aortic dissection (AD) with intimal tear in the descending or abdominal aorta and retrograde extension into the ascending aorta (retrograde AD) remains unknown. The purpose of this study was to elucidate medium-term prognosis of patients with retrograde AD. Methods and Results—Study population consisted of 109 patients with acute type A AD. There were 27 patients (25%) with retrograde AD and 82 patients (75%) with intimal tear in the ascending aorta (antegrade AD). In antegrade AD patients, 60 patients underwent surgery and 22 patients were treated medically. In retrograde AD patients, 14 patients showed localized crescentic high attenuation area along the ascending aortic wall without enhancement in computed tomography. Transesophageal echocardiography revealed complete thrombosis of false lumen (FL) in the ascending aorta (retrograde thrombosed). The remaining 13 patients showed incomplete or no thrombosis (retrograde nonthrombosed). All retrograde nonthrombosed AD patients underwent surgery except for 1 patient with stroke, whereas all retrograde thrombosed AD patients were treated medically. In-hospital mortality rate of retrograde AD patients was significantly lower than that of antegrade AD patients (15% versus 38%, P =0.027). The survival rates in retrograde AD patients were all 85% at 1, 2, and 5 years, which were significantly higher than those of antegrade AD patients (63%, 62%, and 57%, respectively)(P =0.009). Conclusions—Patients with type A retrograde AD have better medium-term prognosis than patients with antegrade AD. Retrograde AD patients with thrombosed FL in the ascending aorta could be treated medically with timed surgical repair.

Age and body surface area dependency of mitral valve and papillary apparatus parameters: assessment by real-time three-dimensional echocardiography

AIMS Real-time three-dimensional echocardiography (RT3DE) has been used to quantify mitral valve (MV) annular size and leaflet tenting parameters in small numbers of patients with different pathologies. We sought to establish normal values for RT3DE mitral annular, tenting, and papillary muscle parameters over a wide age range and to study their age and body surface area (BSA) dependency. METHODS AND RESULTS Transthoracic wide-angled RT3DE images of the MV were acquired in 120 subjects (52 females, 68 males, age: 37+/-20 years) with normal left ventricular (LV) function, no risk factors, and less than or equal to mild mitral regurgitation. Custom software (RealView) was used to trace the MV annulus, leaflets, and the papillary apparatus in mid-systole in 18 sequential cut planes obtained from the 3D data sets. Mitral valve annular area and height as well as tenting parameters (maximum and mean tenting height and mid-systolic tenting volume) were obtained and correlated with age and BSA. Wide inter-subject variability was noted in all parameters. Despite this variability, parameters directly affected by LV size were found to be BSA-dependent: MV annular area showed highest correlation with BSA (r=0.78), followed by inter-papillary distance (r=0.58) and postero-medial (PM) and antero-lateral (AL) papillary muscle annular distance (r=0.57 and r=0.46, respectively). Age did not correlate with either annular or tenting parameters, but showed moderate negative correlation with inter-papillary muscle angle (r= -0.52) and mild negative correlation with inter-papillary distance (r= -0.32), both normalized by BSA. CONCLUSIONS Real-time three-dimensional echocardiography-derived MV annular, tenting, and papillary muscle parameters vary widely in normal subjects. When used clinically, normal values of parameters that are age- and/or BSA-dependent need to be adjusted accordingly.