Akihiro Hayashida

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.

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.

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.

Plaque Characteristics of Thin-Cap Fibroatheroma Evaluated by OCT and IVUS

OBJECTIVES The purpose of this study was to assess plaque characteristics of optical coherence tomography (OCT)-derived thin-cap fibroatheroma (TCFA) by integrated backscatter intravascular ultrasound (IB-IVUS). BACKGROUND Radiofrequency signal-derived IVUS tissue characterization technology has become clinically available and provided objective and quantitative plaque characteristics of the coronary vessel wall. Integrated backscatter IVUS is one of the tissue characterization methods that can possibly provide quantitative plaque characteristics of the OCT-derived TCFA. METHODS Eighty-one coronary lesions with plaque burden >40% were selected and analyzed with both IB-IVUS and OCT. The OCT-derived TCFA was defined as a presence of thin fibrous cap (<65 μm) overlying a signal-poor lesion with diffuse border representing a lipid-rich plaque. By conventional gray-scale IVUS, external elastic membrane (EEM) cross-sectional area (CSA), lumen CSA, plaque plus media (P+M) CSA, plaque burden and remodeling index were measured. By IB-IVUS, plaque characteristics were further classified as fibrosis, dense fibrosis, calcification, or lipid pool. RESULTS Optical coherence tomography identified 40 TCFAs (49%) and 41 non-TCFAs. The EEM CSA, P+M CSA, plaque burden, and remodeling index were significantly larger in OCT-derived TCFA than non-TCFA. By IB-IVUS, percentage lipid pool area (= lipid pool area/P+M CSA × 100) was significantly higher (62.4 ± 12.8% vs. 38.4 ± 13.1%, p<0.0001) and percentage fibrosis area (= fibrosis area/P+M CSA × 100) was significantly lower (34.6 ± 11.4% vs. 50.5 ± 8.7%, p<0.0001) in OCT-derived TCFA than non-TCFA. By receiver-operator characteristic curve analysis, percentage lipid pool area ≥55%, percentage fibrosis area ≤41%, and remodeling index ≥1.0 were predictors of OCT-derived TCFA. CONCLUSIONS The OCT-derived TCFA had larger plaque burden and positive remodeling with predominant lipid component and less fibrous plaque assessed by IB-IVUS.

Usefulness of CHADS2 Score to Predict C-Reactive Protein, Left Atrial Blood Stasis, and Prognosis in Patients With Nonrheumatic Atrial Fibrillation

The CHADS2 score (congestive heart failure, hypertension, age >75 years, diabetes, and previous stroke/transient ischemic attack) is used for embolic risk stratification in patients with atrial fibrillation (AF). Although systemic inflammation is a known predictor of left atrial thrombus formation in patients with nonrheumatic AF, the relation between the CHADS2 score and systemic inflammation is unknown. A total of 165 patients with nonrheumatic AF were enrolled and analyzed. According to the CHADS2 score, the study patients were grouped into low- (score 0 to 1), intermediate- (score 2 to 3), or high- (score 4 to 6) risk categories. The plasma C-reactive protein levels, transesophageal echocardiographic findings, and cardiovascular events (death, stroke, and heart failure) were compared. Patients in the high-risk group had significantly greater C-reactive protein levels than those in the intermediate- and low-risk groups (0.80 mg/dl, range 0.21 to 1.50, vs 0.16 mg/dl, range 0.06 to 0.50, vs 0.08 mg/dl, range 0.04 to 0.21, p <0.01). Using transesophageal echocardiography, the incidence of left atrial spontaneous echo contrast and left atrial thrombus increased with an increasing CHADS2 score. During the follow-up period, the cardiovascular event-free survival was significantly lower in the high-risk group than in the intermediate- or low-risk groups. In conclusion, in patients with nonrheumatic AF, CHADS2 score is related to systemic inflammation, left atrial thrombus formation, and prognosis.

Guidelines from the Japanese Society of Echocardiography: Guidance for the management and maintenance of echocardiography equipment

Echocardiography plays a pivotal role as an imaging modality in modern cardiology practice. Information derived from echocardiography is definitely helpful for patient care. The Japanese Society of Echocardiography has promoted echocardiography in routine clinical and research use. One of the missions of the Society is to provide information that is useful for high-quality examinations. To ensure this, we believe that equipment in good condition and a comfortable environment are important for both patient and examiner. Here, the Guideline Preparation Committee of the Japanese Society of Echocardiography has established brief guidance for the routine use of echocardiography equipment.

Systemic inflammation and left atrial thrombus in patients with non-rheumatic atrial fibrillation

BACKGROUND There is an apparent link between thrombogenesis and inflammation. We hypothesized that systemic inflammation [as indicated by C-reactive protein (CRP)] would be related to the presence of left atrial (LA) thrombus in patients with atrial fibrillation (AF). To test this hypothesis, we evaluated the relationship between CRP and LA thrombus in patients with non-rheumatic AF. METHODS AND RESULTS Between October 2004 and December 2008, 190 patients with non-rheumatic AF (122 males, age 71+/-10 years) who underwent transesophageal echocardiography (TEE) were enrolled and analyzed. All patients were examined for presence or absence of LA thrombus by TEE. CRP was measured within 1 week before the TEE examination. LA thrombus was detected in 19 patients (10%). Hypertension, hypertensive heart disease (HHD), valvular heart disease, ticlopidine, and CRP were univariate correlates of LA thrombus. By multivariate analysis, HHD (p<0.01), ticlopidine (p=0.01), and CRP (p=0.03) were independently associated with LA thrombus. A cut-off CRP value for identifying LA thrombus was 0.21mg/dl (sensitivity: 84%, specificity: 60%, positive predictive value: 19%, and negative predictive value: 97%). CONCLUSION A high CRP is related to LA thrombus in patients with non-rheumatic AF.

Impact of right ventricular involvement on the prognosis of takotsubo cardiomyopathy

BACKGROUND Previous studies showed that patients with takotsubo cardiomyopathy had a higher long-term mortality rate than the general population and the incidence of in-hospital complications was higher in takotsubo cardiomyopathy with than without right ventricular (RV) involvement. This study was performed to investigate the long-term prognostic impact of RV involvement in takotsubo cardiomyopathy. METHODS AND RESULTS The clinical data of 113 patients (72.7 ± 11.4 years old, 84 females) with takotsubo cardiomyopathy were studied retrospectively. The patients were divided into two groups according to the presence (biventricular group, n = 21, 18.6%) or absence (classical group, n = 92, 81.4%) of RV involvement assessed by initial echocardiography. The end point was a composite of all-cause death, re-hospitalization due to heart failure, and recurrence of takotsubo cardiomyopathy. The in-hospital mortality rate was significantly higher in the biventricular group than the classical group (14.3 vs. 1.1%, respectively, P = 0.02). Kaplan-Meier analysis indicated a significantly lower event-free survival rate in the biventricular group than the classical group (log-rank, P < 0.001). On multivariate analysis, RV involvement was the only independent predictor of the end point (HR: 2.73, P = 0.026). CONCLUSION The rates of in-hospital and long-term events were significantly higher in takotsubo cardiomyopathy with than without RV involvement, and RV involvement was the independent predictor of the poor prognosis.

A comparison between 40 MHz intravascular ultrasound iMap imaging system and integrated backscatter intravascular ultrasound.

BACKGROUND iMap is a newly developed intravascular ultrasound (IVUS) tissue characterization system based on pattern recognition of the radio frequency (RF) signals. PURPOSE The purpose of this study was to compare tissue characterization between iMap and another previously validated tissue characterization system, integrated backscatter (IB)-IVUS in vivo and to clarify similarities and differences between these two methods. METHODS A total of 31 lesions from 16 patients with ischemic heart disease were studied. IVUS imaging was performed using 40 MHz IVUS catheter. RF signals from each lesion were then exported to analyze tissue characterization using both iMap and IB-IVUS. By iMap, coronary plaque was classified into four categories, fibrotic, lipidic, necrotic, or calcified. By IB-IVUS, coronary plaque was classified into four categories, fibrosis, lipid pool, dense fibrosis, or calcification. After the images were acquired, IB-IVUS and iMap images were compared at exactly the same cross-sections. Because severe calcification is a perfect reflector, dense calcification lesions (>20%) were excluded. RESULTS Both fibrotic and calcified by iMap correlated well with fibrosis and calcification by IB-IVUS (fibrotic vs. fibrosis: r(2)=0.522, p<0.001, calcified vs. calcification: r(2)=0.560, p<0.001). Although lipidic by iMap did not correlate with lipid pool by IB-IVUS, necrotic by iMap correlated well with lipid pool by IB-IVUS (r(2)=0.480, p<0.001). CONCLUSION Although tissue types classified by iMap correlated well with corresponding tissue type by IB-IVUS, some discrepancy presented between the two systems. These results may call for careful interpretation of the tissue types obtained by the different IVUS tissue characterization systems.

Quantitative measurement of mitral valve coaptation in functional mitral regurgitation: In vivo experimental study by real-time three-dimensional echocardiography

BACKGROUND The degree of mitral valve (MV) coaptation should be an important parameter in the assessment of functional mitral regurgitation (MR). This study aimed to quantify the degree of MV coaptation in experimental models of functional MR caused by acute left ventricular (LV) pressure overload, using real-time three-dimensional (3D) echocardiography. METHODS AND RESULTS Using canine models, LV pressure overload was induced by staged ascending aortic banding. Echocardiographic examinations were performed before and during the aortic banding. By using a novel software system for 3D quantification (REALVIEW®), the annulus and leaflet were traced manually both at the onset of MV closure and at the maximum MV closure. The coaptation index was calculated by the following formula: [(3D tenting surface area at the onset of MV closure-3D tenting surface area at the maximum MV closure)/3D tenting surface area at the onset of MV closure] x 100. MR area gradually increased with the decrease in coaptation index during progressively exacerbated aortic banding. MR area was significantly correlated with the coaptation index. A coaptation index < 12 had a high sensitivity and specificity in the presence of significant MR. CONCLUSIONS The degree of MV coaptation can be quantified using 3D echocardiography. The coaptation index should be a useful parameter in the assessment of functional MR.