Hiroaki Maeda

Prevalence of carotid atherosclerosis in diabetic patients. Ultrasound high-resolution B-mode imaging on carotid arteries.

OBJECTIVE To quantitatively assess atherosclerosis of the carotid artery in subjects with and without diabetes. RESEARCH DESIGN AND METHODS Ultrasound high resolution B-mode imaging of carotid arteries was conducted on 71 nondiabetic subjects without hyperlipidemia or hypertension and 295 diabetic patients to determine IMT of the arterial wall. RESULTS IMT was linearly related with age in nondiabetic (IMT = [0.0087 × age] + 0.3318) and diabetic subjects (IMT = [0.0155 × age] + 0.32450). The regression coefficient for age was significantly greater in diabetic than nondiabetic subjects. IMT (mean ± SD) of diabetic subjects aged 20–29 was significantly > that of nondiabetic subjects aged 20–29 (0.73 ± 0.27 vs. 0.52 ± 0.07 mm, P < 0.01). Multivariate regression analysis of 275 NIDDM patients indicated smoking, hyperlipidemia, duration of diabetes, hypertension, and age were factors determining thickness of the carotid arterial wall. CONCLUSIONS Diabetes, along with age, hyperlipidemia, smoking, and hypertension, aggravates carotid atherosclerosis.

Ischemic stroke events and carotid atherosclerosis : results of the Osaka follow-up study for ultrasonographic assessment of carotid atherosclerosis (the OSACA study)

BACKGROUND AND PURPOSE To clarify the clinical significance of carotid atherosclerosis for ischemic stroke events, a follow-up study was performed in Japanese patients. METHODS Two hundred fourteen patients were registered from nine hospitals in the Osaka community. All patients were checked for a prior history of stroke, and the risk factors for stroke and atherosclerosis were evaluated. Carotid atherosclerosis was assessed by 7.5-MHz duplex ultrasonography. We studied the relationship between the ischemic stroke event rate and the severity and appearance of the carotid atherosclerosis. We also studied the relationship between stroke events and various risk factors. RESULTS The average duration of follow-up was 16 months. Ten patients suffered new ischemic stroke episodes during this follow-up period. At the initial ultrasonographic study, 16 patients had high-grade stenosis and 21 had ulcerated plaque. Proportional hazard regression analysis showed that grade of stenosis and plaque ulceration were positively related to the event rate. Patients with ulcerated plaque had a sevenfold higher hazard ratio for stroke in comparison to those without (P < .01). The ipsilateral stroke recurrence rate was 11 times higher in patients with ulcerated high-grade stenotic carotid lesions. CONCLUSIONS The present findings demonstrate that the severity of carotid atherosclerosis as evaluated by ultrasonography is a useful indicator of the risk of ischemic stroke in symptomatic patients.

Carotid lesions detected by b mode ultrasonography in takayasu's arteritis macaroni sign as an indicator of the disease

Twenty-three patients were studied to evaluate the clinical usefulness of high resolution B-mode ultrasonography in the detection of carotid lesions in patients with Takayasus arteritis. In each patient the carotid arteries were examined using both B-mode ultrasonography (midfrequency of 7.5 MHz) and contrast angiography. In 19 of 23 patients, B-mode ultrasonography clearly demonstrated the characteristic circumferential arterial wall thickening of either one or both sides of the common carotid arteries as a macaroni-like, diffusely thickened intima-media complex. Conversely, contrast angiography demonstrated carotid lesions in only 13 of 23 patients. These results clearly show that B-mode ultrasonography is quite sensitive and superior in the detection of the characteristic thick intima-media complex of the common carotid artery in patients with Takayasus arteritis, when compared with contrast angiography that is usually used for the definitive diagnosis of this disease.

A validation study on the reproducibility of transcranial doppler velocimetry

The transcranial Doppler method for the measurement of intracranial arterial blood flow velocity is a useful noninvasive technique with a number of applications. The present study validated the reproducibility of this method for repeated measurements of flow velocity in the middle cerebral and basilar arteries. Fifteen healthy volunteers were studied. Measurements were made twice by one examiner and once by another in a single day and again by the first examiner on another day. The reproducibility was evaluated by calculating the correlation coefficient (r) and the coefficient of variation (CV) of the difference between the values obtained from each pair of measurements. Although depending on the examiner, the time interval between the examinations and the vessels studied some differences were noted in the reproducibility, both the r (0.69-0.95) and CV (6.7%-19.5%) values in the whole study were good enough to warrant the applicability of this method for the repeated measurements of the intracranial arterial blood flow velocity in future studies.

Reactivity of cerebral blood flow to carbon dioxide in hypertensive patients: evaluation by the transcranial Doppler method.

OBJECTIVE To evaluate hypertensive cerebral involvement before cerebrovascular accidents. DESIGN Cerebral microvascular responses to changes in the arterial partial pressure of CO2 (pCO2; the CO2 reactivity) were compared among patients with different stages and severity of hypertensive disease. PATIENTS Fifty-eight patients with hypertension, 11 with borderline hypertension, 15 hypertensives with cerebral infarction and 58 normotensive controls were studied. METHODS The cerebrovascular CO2 reactivity was determined by measuring simultaneously the end-tidal pCO2 and the blood flow velocity in the middle cerebral artery using transcranial Doppler sonography under hypocapnic, normocapnic and hypercapnic conditions. RESULTS CO2 reactivity was impaired in the hypertensive patients compared with in the normotensive controls, but less so than in the symptomatic hemisphere of the hypertensive patients with cerebral infarction. The CO2 reactivity in the borderline hypertensive patients was greater than that in both the symptomatic and asymptomatic hemispheres of the hypertensive patients with cerebral infarction. In the subjects without cerebral infarction, two risk factors for cerebral atherosclerosis (age and hypertension) were negatively correlated with cerebrovascular CO2 reactivity. In the hypertensive patients age and the estimated duration of hypertension were negatively correlated with cerebrovascular CO2 reactivity. CO2 reactivity in the patients with hypertensive or arteriosclerotic retinopathy or ST-T changes on their electrocardiogram was impaired compared with that in the patients without such changes. CONCLUSIONS Hypertension affected the microvascular reactivity of the brain before the development of cerebrovascular accidents, and its effect varied dependently on the extent of involvement of other target organs.

Silent cerebral infarction as a form of hypertensive target organ damage in the brain.

The incidence, number, size, and location of silent cerebral infarction on 0.1 T magnetic resonance imaging was investigated in 66 hypertensive patients (63 +/- 9 years old; mean +/- SD) and 42 age-matched normotensive subjects (61 +/- 9 years old) to determine the clinical significance of hypertension in silent cerebral infarction. Cerebrovascular risk factors and the severity of hypertensive changes in other major target organs were also investigated. The incidence of silent infarction in hypertensive patients (47%) tended to be higher than that of normotensive subjects (33%) and increased significantly with advancing age. In hypertensive patients, a significantly higher incidence of silent lesions was noted in patients with hypertensive changes in major target organs (72-73% in patients with organ involvement versus 33-39% in those without). The average number of lesions in hypertensive patients was significantly higher than that in normotensive subjects (6.0 versus 2.1), and the lesions in the hypertensive patients were more frequently detected in the brain areas supplied by perforating arteries than those in normotensive subjects (47% versus 24%). These results clearly demonstrate that silent cerebral infarction is frequently seen in older hypertensive patients, especially when moderate hypertensive changes are noted in major target organs, and suggest that hypertensive arterial changes play a crucial role in the occurrence of silent infarction.

Extracranial carotid atherosclerosis as an important predictor for silent brain infarction.

無症候性脳梗塞患者における頸部頸動脈病変の臨床的意義を明らかにする為, 脳卒中危険因子 (高血圧, 耐糖能異常, 高脂血症, 虚血性心疾患) を有するも神経学的に異常の無い外来患者117例に頸部超音波断層法とMRIを施行し, 頸動脈硬化度, 狭窄度, 潰瘍形成の有無と無症候性脳梗塞合併率, 個数, 大きさ, 局在との関係を検討した.頸動脈硬化度が重症な例ほど, また, 高度狭窄や潰瘍合併例では非合併例に比し, 無症候性脳梗塞合併率は高値を呈し, この傾向は各年台別の検討でも認められた.梗塞の特徴は, 皮質下や基底核の多発小梗塞であったが, 特に, 高度狭窄例や潰瘍形成例では比較的大きい梗塞を頸動脈病変側の脳半球に高率に認めた.他の危険因子では, 高血圧のみが梗塞発現に有意に関与した.以上, 頸動脈病変の存在が無症候性脳梗塞発現に密接に関与することが示され, 脳卒中危険因子を有する例における頸部超音波断層法の有用性が明らかとなった.