Hisao Hara

Ultrasound attenuation behind coronary atheroma without calcification: Mechanism revealed by autopsy

When performing intravascular ultrasound studies, the backward echo image can show marked attenuation, although there are no calcified deposits and it may be impossible to detect the intraplaque architecture. The pathology underlying this phenomenon was investigated in autopsy specimens. We hypothesize that the mechanism responsible for the attenuation involves micro‐calcification and lipid in unstable plaques causing ultrasonic wave reflection and dispersion.

Intravascular ultrasonic comparisons of mechanisms of vasodilatation of cutting balloon angioplasty versus conventional balloon angioplasty

Intimal hyperplasia after balloon dilatation may be related to the severity of vascular injury, and cutting balloon angioplasty (CBA) may reduce vascular injury. The present study investigated the mechanism of vasodilation by CBA. Intravascular ultrasound examination was performed before and after intervention in 40 lesions treated with CBA and in 25 lesions treated with conventional balloon angioplasty. Intravascular ultrasound measurements included the vessel area, luminal area, and plaque area. Vessel expansion was evaluated as the ratio of the postprocedural vessel area to that before intervention. The vessel area was 13.9 +/- 3.2 and 14.8 +/- 3.2 mm(2) after CBA versus conventional angioplasty, respectively, whereas the luminal area was 5.5 +/- 1.2 versus 5.7 +/- 1.2 mm(2) and the plaque area was 8.5 +/- 2.7 versus 9.1 +/- 2.2 mm(2), respectively. The vessel area was smaller and the plaque area significantly smaller after CBA. Vessel expansion accounted for 45% of luminal enlargement, and plaque compression or shift accounted for 55% after CBA. After conventional angioplasty, vessel expansion accounted for 67%, and plaque compression or shift for 33% of luminal enlargement. The vessel expansion ratio was significantly smaller after CBA than after conventional angioplasty (1.05 vs 1.22, p <0.05). These findings suggest that the predominant mechanism of dilatation after CBA is plaque compression or shift rather than vessel expansion, unlike conventional angioplasty.

Relationship between tissue characterization with 40 MHz intravascular ultrasound imaging and 64-slice computed tomography

BACKGROUND Identification of coronary plaque composition is important for selecting the treatment strategy, and 64-slice computed tomography (CT) is a noninvasive method of characterizing atherosclerotic plaques. However, the correlation between plaque characteristics detected by CT and intravascular ultrasound (IVUS) is not clear. A 40 MHz IVUS imaging system (iMap-IVUS) has recently been developed to evaluate plaque composition. The aim of this study was to compare iMap-IVUS with 64-slice CT angiography for the characterization of non-calcified coronary plaques. METHODS AND RESULTS Both 64-slice CT angiography and iMap-IVUS were performed in 19 patients (38 plaques). CT values were measured as Hounsfield units (HU) in circular regions of interest (ROI) drawn on the plaques. The iMap-IVUS system analyzed coronary plaques as fibrotic, lipidic, necrotic, or calcified tissue based on the radiofrequency spectrum. A positive correlation was found between CT values and the percentage of fibrotic plaque (r=0.34, p=0.036) or calcified plaque (r=0.40, p=0.011). Conversely, a negative correlation was found between CT values and the percentage of lipidic plaque (r=-0.41, p=0.01), or necrotic plaque (r=-0.41, p=0.01). CONCLUSIONS Good correlations were observed between the characteristics of non-calcified plaque determined by iMap-IVUS and the CT values of plaque detected by 64-slice CT scanning.

Relationship between tissue characterisations with 40 MHz intravascular ultrasound imaging and slow flow during coronary intervention.

AIMS To evaluate the plaque characteristics that predispose to the slow flow phenomenon during percutaneous coronary intervention (PCI). The slow flow phenomenon is a serious complication of PCI and is associated with poor prognosis. It is difficult to predict this phenomenon from greyscale intravascular ultrasound (IVUS) data obtained before PCI. iMap™ is a new software package for assessing plaque composition from data obtained by 40 MHz IVUS imaging. METHODS AND RESULTS Ninety-five consecutive patients underwent 40 MHz IVUS, including 33 with acute coronary syndrome. Plaque volume was calculated by IVUS and plaque components were detected by iMap software. Plaques were characterised as fibrotic, lipidic, necrotic, or calcified. Correlations among plaque characteristics and the slow flow phenomenon were analysed. Slow flow during PCI was observed in 11 patients (11.6%). Both the absolute volume and percentage of necrotic plaque were significantly higher in the slow flow group than the normal flow group (43.3±33.5 mm3 vs. 20.1±17.2 mm3, p=0.0004, 19.7±5.1% vs. 14.6±8.3%, p=0.047). Receiver-operating characteristic analysis showed that the necrotic plaque volume and necrotic plaque ratio were significantly better predictors of slow flow during PCI compared with total plaque volume. The cut-off value of necrotic plaque volume for predicting slow flow was 21.6 mm3 (sensitivity of 81.8% and specificity of 61.9%). CONCLUSIONS Characterisation of plaque by IVUS with iMap analysis may predict slow flow during PCI.

Comparison of characteristics and healing course of diabetic foot ulcers by etiological classification: Neuropathic, ischemic, and neuro-ischemic type

AIMS To identify differences in the characteristics of patients with diabetic foot ulcers (DFUs) according to their etiological classification and to compare their healing time. METHODS Over a 4.5-year period, 73 patients with DFUs were recruited. DFUs were etiologically classified as being of neuropathic, ischemic, or neuro-ischemic origin. Descriptive analyses were performed to characterize study subjects, foot-related factors, and healing outcome and time. Duration of healing was assessed using the Kaplan-Meier method. Healing time among the three types was compared using the log rank test. RESULTS The number of patients manifesting neuropathic, ischemic, and neuro-ischemic ulcers was 30, 20, and 14, respectively. Differences were identified for age, diabetes duration, body mass index, hypertension, and estimated glomerular filtration rate. Patients with neuro-ischemic ulcers had better ankle-brachial index, skin perfusion pressure (SPP), and transcutaneous oxygen pressure values compared to those with ischemic ulcers. The average time in which 50% of patients had healed wounds was 70, 113, and 233 days for neuropathic, neuro-ischemic, and ischemic ulcers, respectively. Main factors associated with healing were age and SPP values. CONCLUSIONS Based on the etiological ulcer type, DFU healing course and several patient factors differed. Failure to consider the differences in DFU etiology may have led to heterogeneity of results in previous studies on DFUs.

Aggressive statin therapy in multicenter and effectiveness for the reduction of intra-myocardial damage caused by non-ST elevation acute coronary syndrome: AMERICA study

Background: While preprocedural statin treatment for acute coronary syndrome (ACS) is widely regarded as beneficial, there has been no prospective randomized multicenter trial of patients with non-ST elevation ACS in the Japanese population to examine the efficacy of preprocedural aggressive statin use. The aim of this study was to confirm this effect by prospective randomized multicenter design. Methods: Fifty patients who presented with non-ST elevation ACS were enrolled, and randomly assigned to aggressive statin administration before percutaneous coronary intervention (PCI). Troponin-T (TnT), creatine phosphokinase (CK), CK-myocardial band (CK-MB), high-sense C-reactive protein (hs-CRP), and brain natriuretic peptide (BNP) were measured at baseline and/ or after procedure. Results: Three days after PCI, the statin group had significantly less CK elevation compared with the nonstatin group (84±17 IU/l versus 180±68 IU/l, respectively, p = 0.02). CK-MB elevation also tended to be lower in the statin group than in the nonstatin group (3.2±1.9 versus. 7.0±3.0, respectively, p = 0.07), as was BNP level (3.2±1.9 versus 7.0±3.0 pg/ml, respectively, p = 0.07). The change of serum LDL cholesterol was significantly correlated with CK (p = 0.01) and TnT (p = 0.02) at 1 day after PCI. Conclusions: Aggressive statin usage before PCI to Japanese patients with non-ST elevation ACS appears to reduce myocardial damage after procedure. The degree of serum lipid level reduction may reflect the vulnerability of atheromatous plaques that could cause cardiac damage after PCI.

Stent deformation: an experimental study of coronary ostial stenting☆

OBJECTIVES To investigate stent deformation by torsional stress after implantation at the ostium of a model coronary artery. BACKGROUND Little is known about coronary stent deformation, especially the association between stent design and deformation at the coronary ostium. Recent reports have suggested that mechanical factors are important for stent restenosis. METHODS A coronary ostium model was constructed and three different stents (Express(2), Cypher, and Tsunami, n=5 each) were implanted at the aorto-ostial junction. Differences of stent deformation were assessed after exposure to torsional stress. Intravascular ultrasound was used to measure the luminal area along each stent. Then the extent and pattern of plastic deformation were compared between the three stent types. RESULTS The Express(2) stents and Cypher stents both showed significant deformation (P<.0001 and P=.045, respectively) adjacent to the ostium, whereas only a minimal decrease of luminal area was observed with the Tsunami stent. In the central and distal parts of each stent, the decrease of luminal area was minimal and no differences were noted among the three types. Sudden fracture of a Cypher stent strut occurred during the experiment. CONCLUSION Differences of structural characteristics influence permanent plastic deformation at sites where continuous stress occurs, such as the coronary ostium. A more elastic design may show better resistance to such stress.

1,5-Anhydro-D-glucitol predicts coronary artery disease prevalence and complexity.

BACKGROUND The relationship between hemoglobin A1c (HbA1c) levels and coronary artery disease (CAD) has previously been confirmed. Serum 1,5-anhydro-D-glucitol (1,5-AG) levels are a useful clinical marker for short-term glycemic status that reflect glycemic excursions with greater sensitivity compared with HbA1c, specifically in the postprandial state. Postprandial hyperglycemia is an important CAD risk factor. Thus, the aim of this study was to compare HbA1c with 1,5-AG as a CAD predictor. METHODS The subjects consisted of 336 consecutive patients who underwent their first coronary angiography between July 2011 and March 2013. The relationship between CAD prevalence and HbA1c as well as CAD prevalence and 1,5-AG levels was evaluated. The correlation between CAD complexity and HbA1c or 1,5-AG was also assessed. CAD complexity was evaluated by the SYNTAX score. RESULTS CAD patients presented with significantly lower 1,5-AG and higher HbA1c values than patients without CAD (11.6 μg/ml [6.1, 19.1] vs. 17.6 μg/ml [11.9, 25.0], p<0.001, and 6.0% [5.6, 7.1] vs. 5.7% [5.4, 6.2], p<0.001, respectively) (median [25th, 75th percentiles]). According to logistic regression analysis, 1,5-AG was a predictor of CAD prevalence (odds ratio 0.94, 95% confidence interval 0.90-0.97). However, HbA1c levels did not present a predictive value for CAD. Levels of 1,5-AG and HbA1c were significantly correlated with SYNTAX scores (ρ=-0.27, p<0.001; and ρ=0.23, p<0.001, respectively). CONCLUSIONS The use of 1,5-AG, may be superior to HbA1c in predicting CAD prevalence. Both 1,5-AG and HbA1c correlate with CAD complexity.

Coronary artery fistula with an associated aneurysm detected by 16-slice multidetector row computed tomographic angiography

We describe a case of a 60-year-old man with effort-induced angina pectoris. Coronary angiography showed an aneurysm in the proximal left anterior descending coronary artery. It was unclear whether it was a coronary artery aneurysm or a coronary fistula with an associated aneurysm. Three-dimensional reconstruction images from 16-slice multidetector row computed tomographic (MDCT) angiography showed an aneurysm that drained into the pulmonary artery. Images from 16-slice MDCT coronary angiography can be helpful in understanding complex coronary artery anatomy.

Distribution of ultrasonic radiofrequency signal amplitude detects lipids in atherosclerotic plaque of coronary arteries: an ex-vivo study

BackgroundAccumulation of lipids within coronary plaques is an important process in disease progression. However, gray-scale intravascular ultrasound images cannot detect plaque lipids effectively. Radiofrequency signal analysis could provide more accurate information on preclinical coronary plaques.MethodsWe analyzed 29 zones of mild atheroma in human coronary arteries acquired at autopsy. Two histologic groups, i.e., plaques with a lipid core (group L) and plaques without a lipid core (group N), were analyzed by automatic calculation of integrated backscatter. One hundred regions of interest were set on the target zone. Radiofrequency signals from a 50 MHz transducer were digitized at 240 MHz with 12-bit resolution. The intensity of integrated backscatter and its distribution within each plaque were compared between the two groups.ResultsAlthough the mean backscatter was similar between the groups, intraplaque variation of backscatter and backscatter in the axial direction were larger in group L than in group N (p = 0.02). Conventional intravascular ultrasound showed extremely low sensitivity for lipid detection, despite a high specificity. In contrast, a cut-off value>32 for the total variance of integrated backscatter identified lipid-containing plaque with a high sensitivity (85%) and specificity (75%).ConclusionCompared with conventional imaging, assessment of the intraplaque distribution of integrated backscatter is more effective for detecting lipid. As coronary atheroma progresses, its composition becomes heterogeneous and multi-layered. This radiofrequency technique can portray complex plaque histology and can detect the early stage of plaque progression.