Taiji Itoh

Rate of successful recording of blood flow signals in the middle cerebral artery using transcranial Doppler sonography.

Background and Purpose To assess the usefulness of transcranial Doppler sonography, we investigated the rate of blood flow signal recording failure in the middle cerebral artery in Japanese subjects. Furthermore, we studied the effect of increased emitted power on the rate of successful recording in some of the patients in whom recording failure had been detected at the standard transducer power of 100 mW/cm2. Methods To evaluate the rate of successful recording, we measured blood flow signals in 597 patients (age range, 16 to 89 years) for screening of cerebrovascular disease by using a 2-MHz range-gated, pulsed-wave Doppler instrument at the standard transducer power. In 18 elderly patients with recording failure at the standard power, we assessed the effect of increased emitted power of 400 mW/cm2 on flow signal recording. Results Blood flow signals were recorded in 920 (77.1%) of the 1194 middle cerebral arteries of the 597 patients studied. The rate of successful recording of bilateral middle cerebral artery flow signals (70.9%; 423 of 597 patients) decreased with age, especially in females (17.0% in women aged 70 years or older). In 12 of 18 elderly patients with recording failure at the standard power, blood flow signals could be detected at the increased emitted power of 400 mW/cm2. Conclusions The rate of successful recording of blood flow signals in Japanese subjects decreases with advancing age, especially in females. Increasing the emitted power markedly improves the successful recording rate.

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.

Asymptomatic carotid lesions and silent cerebral infarction

Background and Purpose Few studies have investigated the relationships between asymptomatic carotid lesions and silent infarcts confirmed on magnetic resonance imaging. Methods A consecutive series of 117 subjects (average age, 62±9.4 years) who were free from neurological deficit but had at least one established risk factor for stroke were investigated by B-mode carotid ultrasonography and magnetic resonance imaging of the brain. Carotid lesions were evaluated by plaque score, maximum percent stenosis, and the existence of ulcerated lesions. The relations between the carotid lesions and the incidence, size, or localization of the brain lesions were investigated. Results The incidence of silent infarcts was 42% in all subjects and significantly increased with advancing age (P<.05). Most lesions were smaller than 1 cm in diameter and were usually localized in the subcortical white matter or the basal ganglia. The percentage of subjects with infarcts in- creased significantly as the plaque score increased (P<.05) or when subjects had high-grade stenosis (P<.05) or ulcerated lesions (P<.01). These relationships were also noted in each decade of age. A higher incidence of larger lesions (>1 cm) was found in the brain hemisphere ipsilateral to the carotid lesion, particularly in subjects with high-grade stenosis or ulcerated lesions (P<.01). Multivariate analysis indicated significant correlations with silent infarcts for age, hypertension, and plaque score. Conclusions Both the severity and characteristics of asymptomatic carotid lesions estimated by B-mode ultrasonography were closely related to the appearance of silent infarcts. These results demonstrate that noninvasive assessment of carotid lesions can be useful in predicting the existence of silent cerebral infarction even in patients free from neurological deficits.

Reactivity of cerebral blood flow to carbon dioxide in various types of ischemic cerebrovascular disease: evaluation by the transcranial Doppler method.

Background and Purpose The response of cerebral blood flow to changes in the arterial carbon dioxide partial pressure (i.e., carbon dioxide reactivity) has been evaluated as a parameter of cerebral perfusion reserve in patients with cerebrovascular disease. In this study, variations in this reactivity in various ischemic cerebrovascular diseases were evaluated by a newly established method, a transcranial Doppler technique. Methods Thirty-three patients with symptomatic cerebrovascular disease, 13 patients with asymptomatic cerebral infarction, and 25 age-matched normal control subjects were investigated. The symptomatic patients were divided into three groups; those with unilateral carotid artery obstruction, those with cortical infarction, and those with lacunar infarction. The carbon dioxide reactivity of each subject was determined by simultaneously measuring the mean spatial Doppler frequency in the middle cerebral artery and the end-tidal carbon dioxide partial pressure under normocapnia hypercapnic, and hypocapnic conditions. Results In the patients with carotid obstruction, the carbon dioxide reactivity of the hemisphere ipsilateral to the obstruction was more impaired than the reactivity of the symptomatic hemispheres in any other group, and was significantly less than in the contralateral asymptomatic hemisphere (p<0.01). In patients with cortical infarction, the carbon dioxide reactivity of the symptomatic hemisphere was significantly less than in normal control subjects (p<0.05) and was also less than that of the contralateral asymptomatic hemisphere (p<0.05). In patients with lacunar infarction, the carbon dioxide reactivity of both hemispheres was significantly less than that in normal controls (p<0.01), although there was no difference between the symptomatic and asymptomatic hemispheres. In patients with asymptomatic infarction, the carbon dioxide reactivity was also less than that in normal controls (p<0.01). Conclusions The carbon dioxide reactivity of cerebral blood flow measured by this transcranial Doppler technique may be useful for characterizing the hemodynamic changes that occur in various types of ischemic cerebrovascular disease.

Carotid Intima-Media Thickness and Risk of Cardiovascular Events in High-Risk Patients

Background and Purpose: There is epidemiological evidence that increased carotid intima-media thickness (IMT) is a predictor of cardiovascular disease (CVD) events. However, the significance of carotid IMT in high-risk patients in whom risk factors are managed clinically has not been adequately investigated. The purpose of this study was to determine the usefulness of carotid IMT measurement in such patients. Methods: The study comprised 900 outpatients with cardiovascular risk factors or established atherosclerosis. Carotid IMT was calculated as the mean bilateral IMT of the common carotid artery, bifurcation, and internal carotid artery. Baseline vascular risk factors, medications, and history of CVD were recorded at the time of enrollment. The incidence of CVD events was determined prospectively. Results: During a mean follow-up period of 2.6 years, there were 64 CVD events. The relative risk (RR) of a CVD event increased with increased IMT. Association between CVD events and carotid IMT was significant after adjustment for risk factors and history of CVD, showing an increased risk per IMT tertile from the middle tertile (RR, 2.5; 95% confidence interval [CI]: 1.0–6.3) to the highest (RR, 3.6; 95% CI: 1.4–9.0). When patients with a history of CVD were excluded (n = 574), the predictive value of IMT was significant even after adjustment for risk factors (hazard ratio per 1 SD IMT increase was 1.57 [95% CI: 1.11–2.20]). Conclusions: Carotid IMT is an independent predictor of vascular events in high-risk patients in whom risk factors are managed clinically.

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.

Effects of daily alcohol intake on the blood pressure differ depending on an individual's sensitivity to alcohol : oriental flushing as a sign to stop drinking for health reasons

Objective To determine whether flushing of the facial skin in response to alcohol consumption (alcohol flushing) is a warning sign of hypertension. We also sought the relationship between alcohol flushing and other risk factors that may contribute to the development of hypertension. Methods We first investigated the relationship of the aldehyde dehydrogenase 2 (ALDH2) genotype to alcohol flushing for 53 normal volunteers. We evaluated the relationships among hypertension, alcohol consumption, and facial flushing for 1011 middle-aged Japanese men (aged 40–68 years; mean 51.6 ± 5.5 years), on the basis of their responses to questionnaires and health records. Results The first examination of 53 normal volunteers showed that there were differences in the degree of alcohol flushing between the ALDH2 genotypes (P < 0.01). Hypertension was observed in 27.4% of the study population (277 of 1011), and was correlated positively to alcohol consumption (P < 0.01). The prevalence of hypertension differed significantly among these four groups: there was a 22.4% prevalence (70 of 312) among subjects with no flushing, a 33.8% prevalence (113 of 334) among those with slight flushing, a 27% prevalence (84 of 311) among those with visible flushing, and an 18.5% prevalence (10 of 54) among subjects who were almost completely intolerant to alcohol (P < 0.05). In particular, heavy drinkers who consumed ≥ 1.5 Go (a traditional Japanese unit equivalent to 27 g ethanol) a day had a high prevalence of hypertension with slight and visible skin flushing [42% (63 of 150) and 40.7% (24 of 59), respectively]. That a family history of hypertension, greater age, heavy alcohol consumption, obesity, and symptoms of intoxication including flushing were correlated significantly to the prevalence of hypertension for all groups was demonstrated by multiple logistic regression analysis (P < 0.05). Conclusions A repeated heavy alcohol intake could increase the risk of hypertension for Japanese subjects who exhibit skin flushing in response to alcohol consumption. Chronic alcohol intake by subjects with alcohol flushing might bring about a significant increase in blood acetaldehyde levels and cause an additional rise in the blood pressure.

Paradoxical embolism as a cause of ischemic stroke of uncertain etiology. A transcranial Doppler sonographic study.

Background and Purpose This study was designed to test the hypothesis that paradoxical embolization would be a cause of embolic strokes and transient ischemic attacks in patients with stroke of uncertain etiology in all age groups. Methods Thirty patients who had stroke of uncertain etiology were studied. They were divided into the following three groups: 13 patients with sudden onset (group A), 11 patients with subacute onset (group B), and 6 asymptomatic stroke patients (group C). Eleven patients with stroke of obvious etiology (group D) and 11 normal healthy volunteers (group E) were also studied as controls. In all patients transcranial Doppler sonography and contrast echocardiography were recorded simultaneously after intravenous injection of the contrast medium. Findings of positive patent foramen ovale in contrast echocardiography or “chirp” sounds in transcranial Doppler sonography were defined as positive for paradoxical contrast embolization. Radioisotope phlebography of the lower extremities and pulmonary scintigraphy, using technetium‐99 macroaggregated albumin, were performed in all 17 patients who had positive findings of paradoxical contrast embolization and in 12 patients whose findings were negative. Results Positive findings of paradoxical contrast embolization were found in 17 subjects by transcranial Doppler sonography but in only 8 on contrast echocardiography. These positive findings were detected more frequently in group A (77%) than in groups B, D, and E (9%, 18%, and 9%, respectively) (P<.05). In group C, 4 of 6 patients (67%) had positive findings. There were positive findings on both phlebography and pulmonary scintigraphy only in 6 group A patients, with positive findings of paradoxical contrast embolization. Conclusions Transcranial Doppler sonography is a sensitive detector of right‐to‐left shunts. Paradoxical cerebral embolization might be frequent in patients with stroke of unknown etiology, especially when the stroke is of sudden onset. (Stroke. 1994;25:771‐775.)

Effect of transcranial Doppler intensity on successful recording in Japanese patients

The major limitation of transcranial Doppler sonography (TCD) is the failure to obtain data for all patients. The purpose of this study was to determine in detail the effect of increasing ultrasonic acoustic intensity on the rate of successful recording of intracranial blood velocity signals. The study was performed in 239 Japanese patients using a 2-MHz range-gated, pulsed-wave TCD. The middle cerebral artery flow signals were recorded at 76, 152, 228, 304, 380, 456 and 532 mW/cm2 and the results analyzed by age, gender and intensity. The rate of successful recording showed significant increase with the ultrasonic intensity in both genders (45.7% at 76 mW/cm2 vs. 81.1% at 532 mW/cm2 in males and 29.5% vs. 60.7% in females). However, recording was only successful in 54% of aged (50-89 gamma) female patients at the highest ultrasonic intensity used. It should be possible to significantly increase TCD usefulness in an aging Japanese population by further increasing TCD acoustic intensity within safety limitation.