Yoji Neishi

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.

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.

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.

C-Reactive protein predicts severity, progression, and prognosis of asymptomatic aortic valve stenosis

BACKGROUND C-Reactive protein (CRP) has been shown to play a pivotal role in the pathogenesis of atherosclerosis progression. The aim of this study was to assess whether CRP predicts severity, progression, and prognosis of aortic valve stenosis (AS). METHODS One hundred and thirty-five patients with asymptomatic AS were studied. Patients were diagnosed as mild (n = 18, aortic valve area [AVA] > or =1.5 cm(2)), moderate (n = 57, AVA 1.0-1.49 cm(2)), or severe AS (n = 60, AVA <1.0 cm(2)) by Doppler echocardiography. Patients with serial (baseline and at 1 year) echocardiographic examination (n = 47) were grouped as either slow (n = 22, DeltaAVA <-0.15 cm(2)/y) or rapid progression group (n = 25, DeltaAVA > or =-0.15 cm(2)/y). In addition, long-term prognosis was compared between patients with low CRP (n = 68, CRP <0.15 mg/dL) and those with high CRP (n = 67, CRP > or =0.15 mg/dL). RESULTS Baseline CRP was significantly higher in patients with severe AS than in those with mild or moderate AS (mild AS 0.17 +/- 0.43, moderate AS 0.22 +/- 0.28, severe AS 0.53 +/- 0.66 mg/dL, P = .001). By multivariate logistic regression analysis, CRP was an independent predictor of severe AS (odds ratio 3.51, P = .015). Similarly, CRP was significantly higher in the rapid progression group than in the slow progression group (0.56 +/- 0.76 vs 0.19 +/- 0.25 mg/dL, P = .004). Furthermore, long-term survival was significantly lower in the high CRP group than in the low CRP group (log rank: P < .001). CONCLUSION C-Reactive protein predicts severity, progression, and prognosis in patients with asymptomatic AS.

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.

Measurement of acetylcholine-induced endothelium-derived nitric oxide in aorta using a newly developed catheter-type nitric oxide sensor.

Intra-aortic measurement of nitric oxide (NO) would provide valuable insights into NO bioavailability in systemic circulation and vascular endothelial function. In the present study, we thus developed a catheter-type NO sensor to measure intra-aortic NO concentration in vivo. An NO sensor was encased and fixed in a 4-Fr catheter. The sensor was then located in the thoracic aorta via the femoral artery through a 7-Fr catheter to measure intra-aortic plasma NO concentration in vivo in anesthetized dogs. Infusion of acetylcholine (10 microg/kg) increased base-to-peak plasma NO level in the aorta by 2.4+/-0.4 nM (n=7). After 20-min infusion of N(G)-methyl-L-arginine (NO synthase inhibitor), changes in plasma NO concentration in response to acetylcholine were attenuated significantly (1.8+/-0.4 nM, P<0.003, n=7). In conclusion, the newly developed catheter-type NO sensor successfully measured acetylcholine-induced changes in intra-aortic plasma concentration of endothelium-derived NO in vivo and demonstrated applicability to direct evaluation of intravascular NO bioavailability.

Fibrin Clot Visualized by Optical Coherence Tomography

Optical coherence tomography (OCT) is a recently developed optical imaging technique that provides high-resolution (≈10 to 20 μm) cross-sectional images of vessels.1 It has been reported that OCT images of white and red thrombus were characterized as backscattering protrusions in the coronary lumen.2 However, OCT characteristics of fibrin clot composed of fibrin material and few blood cells have not been described. The coronary arteries of a 75-year-old man …