颈动脉系统短暂性脑缺血发作患者侧支循环的分析

目的探讨颈动脉系统病变引起的短暂性脑缺血发作（TIA）患者的侧支循环开放情况。方法回顾性分析135例TIA患者的临床资料,根据DSA显示的血管影像,将颈动脉系统TIA患者分为3组：颅内动脉病变组（A组）60例、颅外动脉病变组（B组）52例、颅内外动脉均有病变组（C组）23例。分析3组侧支循环开放情况及脑动脉狭窄程度与侧支循环开放的关系。结果①3组侧支循环的总开放发生率为70.4%（95/135）,A组侧支循环开放发生率为56.7%（34/60）,B组为84.6%（44/52）,C组为73.9%（17/23）。组间开放发生率比较差异有统计学意义（χ2=10.584,P〈0.01）。②3组患者侧支循环的开放以Willis环吻合形式的开放发生率最高（51.9%）,Willis环吻合开放发生率组间比较,以B组最高（67.3%）,A组最低（38.3%）,P〈0.01;颅内外吻合和脑膜支吻合开放发生率接近,分别为21.5%和20.0%;颅内外吻合以B组最高（42.3%）,A组仅1.7%,P〈0.01;软脑膜支吻合各组接近,P〉0.05。③A、B两组闭塞的患者分别为9例和13例,均有侧支开放。单侧狭窄者B组侧支循环开放发生率（78.6%）高于A组（48.8%）,χ2=6.291,P〈0.05。结论侧支循环开放发生率为颅内动脉病变低于颅外动脉病变。动脉狭窄越严重,侧支循环开放发生率越高。Willis环吻合为主要的侧支循环开放形式。     

Brain circulation in cerebral transient ischemic attacks.

Cranial blood flow, mean cranial transit time and cranial blood volume were measured by the intravenous RISA technique in 10 patients with cerebral transient ischemic attacks (TIA) at the various time intervals from the onset of last attack. Cranial blood flow was subnormal in 5 out of 11 determinations and mean transit time trended to be prolonged in the diseased hemisphere in cases suggestive of the unilateral hemispheric lesion. A decrease in cranial blood flow was observed in TIA with lowering of heart rate below 60/min, or with atrial fibrillation, whereas no obvious correlation was present between heart rate and cranial blood flow either in 94 patients with, or with 62 patients without cerebrovascular diseases. Cardiac dysrhythmias including bradycardia, leading to reduce perfusion to the brain was discussed as a possible factor for producing TIA.     

Intravascular electric impedance spectroscopy of atherosclerotic lesions using a new impedance catheter system

Newer techniques are required to identify atherosclerotic lesions that are prone to rupture. Electric impedance spectroscopy (EIS) can characterize biological tissues by measuring the electrical impedance over a frequency range. We tested a newly designed intravascular impedance catheter (IC) by measuring the impedance of different stages of atherosclerosis induced in an animal rabbit model. Six female New Zealand White rabbits were fed for 17 weeks with a 5% cholesterol–enriched diet to induce early forms of atherosclerotic plaques. All aortas were prepared from the aortic arch to the renal arteries and segments of 5–10 mm were marked by ink spots. A balloon catheter system with an integrated polyimide–based microelectrode structure was introduced into the aorta and the impedance was measured at each spot by using an impedance analyzer. The impedance was measured at frequencies of 1 kHz and 10 kHz and compared with the corresponding histomorphometric data of each aortic segment.Forty–four aortic segments without plaques and 48 segments with evolving atherosclerotic lesions could be exactly matched by the histomorphometric analysis. In normal aortic segments (P0) the change of the magnitude of impedance at 1 kHz and at 10 kHz (|Z|_{1 kHz} – |Z|_{10 kHz}, = ICF) was 208.5 ± 357.6 Ω. In the area of aortic segments with a plaque smaller than that of the aortic wall diameter (PI), the ICF was 137.7 ± 192.8 Ω. (P 0 vs. P I; p = 0.52), whereas in aortic segments with plaque formations larger than the aortic wall (PII) the ICF was significantly lower –22.2 ± 259.9 Ω. (P0 vs. PII; p = 0.002). Intravascular EIS could be successfully performed by using a newly designed microelectrode integrated onto a conventional coronary balloon catheter. In this experimental animal model atherosclerotic aortic lesions showed significantly higher ICF in comparison to the normal aortic tissue.     

Arterial wall stiffness is associated with peripheral circulation in patients with type 2 diabetes

The prevalence of peripheral vascular disease (PVD) in diabetic patients is manyfold higher than that of age- and sex-matched nondiabetic subjects. This study was designed to evaluate the relationship between quantitatively determined peripheral circulation in the lower extremities and arterial wall thickness or stiffness in 68 patients with type 2 diabetes. Peripheral circulation during treadmill-exercise was monitored by transcutaneous oxygen tension (TcPO2) and was expressed as percentage of post-exercise TcPO2 adjusted by that of pre-exercise (TcPO2 index). Arterial wall thickness (intima-media thickness; IMT) and stiffness (stiffness beta) were measured by ultrasonography. TcPO2 index was negatively (r=-0.350, P=0.0007) correlated with stiffness beta, not with IMT, of the femoral artery. In patients without insulin therapy (n=52), both fasting plasma insulin concentration (r=-0.323, P=0.0023) and HOMA IR, an insulin resistance index, (r=-0.281, P=0.0084) were negatively correlated with TcPO2 index. Multiple regression analyses showed that association of stiffness beta of the femoral artery or HOMA IR with the TcPO2 index was independent of other factors including age, smoking index, ankle brachial pressure index and IMT of femoral artery. Thus, arterial wall stiffness of femoral artery appears to be a major determinant of peripheral circulation in patients with type 2 diabetes.