Cardiac specific transcription factor Csx/Nkx2.5 regulates transient-outward K+ channel expression in pluripotent P19 cell-derived cardiomyocytes

We hypothesized that cerebral blood flow (CBF) regulation in the posterior circulation differs from that of the anterior circulation during a cold pressor test (CPT) and is accompanied by elevations in arterial blood pressure (ABP) and sympathetic nervous activity (SNA). To test this, dynamic cerebral autoregulation (dCA) in the middle and posterior cerebral arteries (MCA and PCA) were measured at three different conditions: control, early phase of the CPT, and the late phase of the CPT. The dCA was examined using a thigh cuff occlusion and release technique. The MCA and PCA blood velocities were unchanged at CPT compared with the control conditions despite an elevation in the ABP. The dCA in both the MCA and PCA remained unaltered at CPT. These findings suggest that CPT-induced elevations in the ABP and SNA did not cause changes in the CBF regulation in the posterior circulation compared with the anterior circulation.

     

Variability of the autoregulation index decreases after removing the effect of the very low frequency band

Dynamic cerebral autoregulation (dCA) estimates show large between and within subject variability. Sources of variability include low coherence and influence of CO2 in the very low frequency (VLF) band, where dCA is active. This may lead to unreliable transfer function and autoregulation index (ARI) estimates. We tested whether variability of the ARI could be decreased by suppressing the effect of the VLF band through filtering. We also evaluated whether filtering had any effect on mean group differences between healthy subjects and acute stroke patients.Data from a recent mobilization stroke study were re-analyzed. Middle cerebral artery cerebral blood flow velocity (MCA-CBFV), mean arterial blood pressure (MABP) and end tidal PCO2 (PetCO2) were obtained in 16 healthy subjects and 27 acute ischemic stroke patients in the supine position. The ARI index was calculated from the transfer function (TF) by using spontaneous BP fluctuations. Three different filtering strategies were compared; no filtering (NF), a high pass filter at 0.04 Hz (Time Domain Filtering: TDF) and a high pass Transfer Function Filter (TFF) at 0.04 Hz. In addition, a simulation study was done to obtain further insight into the effects of the applied filters.The variability of the ARI index decreased significantly only with TFF in healthy subjects (standard deviation (left vs. right) after NF 2.28 vs. 2.36, after TDF 2.13 vs. 2.31 after TFF 1.09 vs. 1.19, p < 0.001).Variability was not significantly reduced in stroke patients. The mean ARI was significantly lower in stroke patients compared to healthy subjects after TFF (affected hemisphere 5.85 ± 1.96 vs. 7.13 ± 1.09, non-affected hemisphere 5.96 ± 1.64 vs. 7.31 ± 1.19, p < 0.01 for both hemispheres), but not after NF or TDF. The simulation study showed that TFF results in an overestimation of the ARI index at low ARI levels (0–3), but in correct estimates at higher ARI levels.Removing the effect of the VLF band with TFF results in less ARI variability in healthy subjects, and in more pronounced group differences between stroke patients and healthy subjects. This will improve diagnostic properties when using TFA for ARI calculation.     

Reproducibility and variability of dynamic cerebral autoregulation during passive cyclic leg raising

Dynamic cerebral autoregulation (dCA) estimates require mean arterial blood pressure (MABP) fluctuations of sufficient amplitude. Current methods to induce fluctuations are not easily implemented or require patient cooperation. In search of an alternative method, we evaluated if MABP fluctuations could be increased by passive cyclic leg raising (LR) and tested if reproducibility and variability of dCA parameters could be improved.Middle cerebral artery cerebral blood flow velocity (CBFV), MABP and end tidal CO₂ (PetCO₂) were obtained at rest and during LR at 0.1 Hz in 16 healthy subjects. The MABP–CBFV phase difference and gain were determined at 0.1 Hz and in the low frequency (LF) range (0.06–0.14 Hz). In addition the autoregulation index (ARI) was calculated.The LR maneuver increased the power of MABP fluctuations at 0.1 Hz and across the LF range. Despite a clear correlation between both phase and gain reproducibility and MABP variability in the rest condition, only the reproducibility of gain increased significantly with the maneuver. During the maneuver patients were breathing faster and more irregularly, accompanied by increased PetCO₂ fluctuations and increased coherence between PetCO₂ and CBFV. Multiple regression analysis showed that these concomitant changes were negatively correlated with the MABP–CBFV phase difference at 0.1 Hz Variability was not reduced by LR for any of the dCA parameters.The clinical utility of cyclic passive leg raising is limited because of the concomitant changes in PetCO₂. This limits reproducibility of the most important dCA parameters. Future research on reproducibility and variability of dCA parameters should incorporate PetCO₂ variability or find methods to keep PetCO₂ levels constant.     

偏头痛患者脑动脉变异及脑血流动力学特征

目的:观察偏头痛患者脑动脉变异及脑血流动力学特征,探讨偏头痛的病因及可能的发病机制。方法:对68例偏头痛患者行全脑血管造影检查,观察其脑血管的发育、变异情况,并进行分类;经颅多谱勒检测双侧大脑前、中、后动脉血流速度。结果:大脑后动脉发育异常29例,大脑前动脉发育异常17例,颈内动脉发育异常2例;总变异率为70.59%。经颅多谱勒显示发育异常侧脑血流速度减慢。结论:脑动脉变异引起的脑血流动力学改变可能是导致偏头痛发生的主要机制。     

Evaluation of impaired dynamic cerebral autoregulation by the Mueller manoeuvre.

Arterial blood pressure (ABP) shows polyphasic changes during the Mueller manoeuvre (voluntary negative intrathoracic pressure). The aim of the present study was to investigate (1) whether these changes could be applied to detect impaired dynamic cerebral autoregulation (dCA) in carotid stenosis and (2) whether the degree of indicated impairment correlates with transfer function phase as another current measure for dCA (deep breathing method) and CO2-reactivity. We examined 13 patients with severe unilateral carotid artery stenosis and 16 age-matched controls during 15-s Mueller manoeuvres (MM) at -30 mmHg using bilateral transcranial Doppler sonography and non-invasive ABP recordings (Finapres, 2300, Ohmeda, Englewood, CO, USA). After an initial biphasic oscillation, cerebral blood flow velocity (CBFV) and ABP decreased to below baseline. CBFV reincreased in controls and on contralateral sides in patients 6.0 s (3.8-9.5 s, median and range) after the onset of the decrease, despite a further fall in ABP. CBFV over the affected side revealed a significantly delayed reincrease (8.0 (5.6-10.3) s; P<0.01) combined with a relatively flat and inertial amplitude behaviour. An applied autoregulation index derived from the MM (mROR), phase shift and CO2-reactivity were severely reduced on the affected side in patients (P<0.01). Reduction of the mROR correlated significantly with reduction of phase shift (r=0.69; P=0.002) and CO2-reactivity (r=0.78; P=0.002). In conclusion, the different cerebral haemodynamic pattern during the MM in patients is likely to reflect impaired dCA. The degree of indicated impairment correlates with that of transfer function phase and CO2-reactivity. Therefore, the MM represents a convenient method for grading of compromised cerebral haemodynamics in patients with carotid artery stenosis.     

Dynamic cerebral autoregulation: different signal processing methods without influence on results and reproducibility

Cerebral autoregulation controls cerebral blood flow under changing cerebral perfusion pressure. Standards for measurement and analysis of dynamic cerebral autoregulation (dCA) are lacking. In this study, dCA reproducibility, quantified by intraclass correlation coefficient, is evaluated for different methodological approaches of transfer function analysis (TFA) and compared with multimodal pressure flow analysis (MMPF). dCA parameters were determined in 19 healthy volunteers during three 15-min lasting epochs of spontaneous breathing. Every spontaneous breathing epoch was followed by 5 min of paced breathing at 6 cycles/min. These six measurements were performed in both a morning and an afternoon session. Analysis compared raw data pre-processing by mean subtraction versus smoothness priors detrending. The estimation of spectral density was either performed by averaging of subsequent time windows or by smoothing the spectrum of the whole recording. No significant influence of pre-processing and spectral estimation on dCA parameters was found. Therefore, there seems to be no need to prescribe a specific signal-processing regime. Poor reproducibility of gain and phase was found for TFA as well as for MMPF. Based on reproducibility, no preference can be made for morning versus afternoon measurements, neither for spontaneous versus paced breathing. Finally, reproducibility results are not in favour of TFA or MMPF.     

Nonstationarity of dynamic cerebral autoregulation

Dynamic cerebral autoregulation (dCA), the transient response of cerebral blood flow (CBF) to rapid changes in arterial blood pressure (BP), is usually quantified by parameters extracted from time- or frequency-domain analysis. Reproducibility studies of dCA parameters and consideration of the physiological determinants of the dynamic BP-CBF relationship provide strong indications that dCA is a nonstationary process. As a consequence, new analytical approaches are needed to estimate dCA parameters with greater temporal resolution thus allowing its longitudinal patterns of variability to be assessed in health and disease states. Techniques proposed for this task include ARMA models with moving windows, recursive least-squares, Laguerre–Volterra networks, wavelet phase synchronisation, and multimodal pressure-flow analysis. Initial results with these techniques have revealed the influence of some key determinants of dCA nonstationarity, such as PaCO₂, as well as their ability to reflect dCA impairment in different clinical conditions. One key priority for future work is the development and validation of multivariate time-varying techniques to minimise the influence to the many co-variates which contribute to dCA nonstationarity.     

2260米以上地区经颅多普勒超声脑血流正常值研究

目的：测定２２６０米地区健康人群ＴＣＤ正常参考值。方法：采用ＴＣＤ测定４６１例不同年龄性别世居或移居２２６０￣３８００米地区５年以上健康人颅底动脉血流速度。结果：各动脉血流速度以ＭＣＡ为最高，顺序ＭＣＡ〉ＡＣＡ〉ＢＡ〉ＶＡ〉ＰＣＡ。各动脉血流速度随年龄递减（Ｐ〈０．０１），其差率与国内外报告基本相同。脑血流速度ＭＣＡ的Ｖｄ，ＢＡ、ＶＡ的各期血流速度女性高于男性；ＰＩ偏低，ＰＩ、ＲＩ６０岁前男高于女     

脑中风患者彩色多普勒超声特征研究

目的 用彩色多普勒超声观察中老年人脑中风患者颅内及颈动脉形态、结构和血流动力学改变。方法 应用2．5MHz线阵探头分别观察155例不同类型脑中风患者和80例正常人颈动脉内中膜厚度、斑块情况及颅内与颈动脉血流动力学改变情况。结果 （1）各型脑中风组颈总动脉（CCA）内中膜厚度均较对照组明显增厚,斑块有109例出现（70．3％）,而对照组仅4例（5．0％）出现斑块;（2）各型脑中风组颈内动脉时间平均流速（TAVICA）较正常组减低、阻力指数（RI）、搏动指数（PI）较正常组明显升高;（3）脑梗死组大脑中动脉时间平均流速（TAVMCA）较正常组低,脑出血组TAVMCA较正常组明显升高,混合性中风组可出现TAVMCA升高或降低两种情况。结论 中老年人各型脑中风患者颈动脉粥样硬化程度加重,斑块出现率高及斑块所引起的颈动脉狭窄,对脑中风有直接的因果关系,联合检查颅内动脉和颈动脉血流动力学改变可协助诊断不同类型脑中风,对其疗效观察,预防复发有一定的指导作用。     

Quantitative assessment of cerebral autoregulation from transcranial Doppler pulsatility: a computer simulation study

Transcranial Doppler (TCD) ultrasonography is largely used today to achieve non-invasive assessment of cerebral autoregulation and cerebrovascular reactivity in neurosurgical patients. Recent experimental and clinical studies suggest that not only the pattern of mean velocity, but also velocity pulse amplitude alterations during changes in cerebral perfusion pressure (CPP) contain information on autoregulation status. The aim of this work is to investigate the relationship between cerebral autoregulation and TCD pulsatility by means of a comprehensive mathematical model of intracranial dynamics and cerebrovascular regulation. Simulation results, performed using different values of the most important clinical parameters of the model (autoregulation strength, cerebrospinal fluid (CSF) outflow resistance and intracranial elastance coefficient) show that velocity pulse amplitude increases with a reduction in CPP in patients with intact autoregulation, whereas changes in velocity pulsatility are modest in patients with weak autoregulation. Finally, velocity pulse amplitude decreases during a CPP reduction in patients with impaired autoregulation. Moreover, the relationship between the velocity pulse amplitude changes and autoregulation strength is almost linear in a wide range of CPP values, and is scarcely affected by changes in CSF circulation and intracranial elasticity. Starting from these results, we suggest a new quantitative index to assess autoregulation strength, i.e. G(aut)% = (s-b)/a, where G(aut)% is autoregulation strength (100% means intact autoregulation, 0% means impaired autoregulation), a approximately -0.03; b approximately 1.5 and s is the slope of the relationship ' percentage changes of velocity pulse amplitude to arterial pressure pulse amplitude vs. CPP changes'.     

Early morning impairment in cerebral autoregulation and cerebrovascular CO2 reactivity in healthy humans: relation to endothelial function

The reduction in cerebrovascular reactivity to CO(2) and/or endothelial function that occurs in the early hours after waking are potential causes for the increased risk for cardiovascular events at this time point. It is unknown whether cerebral autoregulation is reduced in the morning. We tested the hypothesis that early morning reduction in endothelium-dependent vascular reactivity would be linked to changes in cerebrovascular reactivity to CO(2) and cerebral autoregulation (CA). Overnight changes in a dynamic cerebral autoregulation index (ARI) were determined from continuous recordings of blood flow velocity in the middle cerebral artery (MCAv) and arterial blood pressure (BP) during transiently induced hypotension in 20 individuals. Frontal cortical oxygenation (near infrared spectroscopy) and cerebral haemodynamics were also monitored during hypercapnia and before and during 3 min of active standing. Brachial artery flow-mediated endothelium-dependent vasodilatation (FMD) and endothelium-independent dilatation (NFMD) were also monitored. From evening to morning, there was a significant lowering in ARI (5.3 +/- 0.5 versus 4.7 +/- 0.6 a.u.; P < 0.05), cerebrovascular reactivity to CO(2) (5.3 +/- 0.6 versus 4.6 +/- 1.1% mmHg(-1); P < 0.05) and FMD (7.6 +/- 0.9 versus 6.0 +/- 1.4%; P < 0.05). The lowered FMD was related to the decrease in cerebrovascular reactivity to CO(2) (r = 0.76; P < 0.05). Transient reductions in morning MCAv and cortical oxyhaemoglobin concentrations were observed upon resuming a supine-to-upright position (P < 0.05 versus evening). The early morning reduction in cerebral autoregulation may facilitate the onset of cerebrovascular accidents; this may be of particular relevance to at-risk groups, especially upon resuming the upright position.     

Structural MRI of carotid artery atherosclerotic lesion burden and characterization of hemispheric cerebral blood flow before and after carotid endarterectomy

Collateral circulation plays a major role in maintaining cerebral blood flow (CBF) in patients with internal carotid artery (ICA) stenosis. CBF can remain normal despite severe ICA stenosis, making the benefit of carotid endarterectomy (CEA) or stenting difficult to assess. Before and after surgery, we assessed CBF supplied through the ipsilateral (stenotic) or contralateral ICA individually with a novel hemisphere-selective arterial spin-labeling (ASL) perfusion MR technique. We further explored the relationship between CBF and ICA obstruction ratio (OR) acquired with a multislice black-blood imaging sequence. For patients with unilateral ICA stenosis (n = 19), conventional bilateral labeling did not reveal interhemispheric differences. With unilateral labeling, CBF in the middle cerebral artery (MCA) territory on the surgical side from the ipsilateral supply (53.7 +/- 3.3 ml/100 g/min) was lower than CBF in the contralateral MCA territory from the contralateral supply (58.5 +/- 2.7 ml/100 g/min), although not statistically significant (p = 0.09). The ipsilateral MCA territory received significant (p = 0.02) contralateral supply (7.0 +/- 2.7 ml/100 g/min), while ipsilateral supply to the contralateral side was not reciprocated. After surgery (n = 11), ipsilateral supply to the MCA territory increased from 57.3 +/- 5.7 to 67.3 +/- 5.4 ml/100 g/min (p = 0.03), and contralateral supply to the ipsilateral MCA territory decreased. The best predictor of increased CBF on the side of surgery was normalized presurgical ipsilateral supply (r(2) = 0.62, p = 0.004). OR was less predictive of change, although the change in normalized contralateral supply was negatively correlated with OR(excess) (=OR(ipsilateral) - OR(contralateral)) (r(2) = 0.58, p = 0.006). The results demonstrate the effect of carotid artery stenosis on blood supply to the cerebral hemispheres, as well as the relative role of collateral pathways before surgery and redistribution of blood flow through these pathways after surgery. Unilateral ASL may better predict hemodynamic surgical outcome (measured by improved perfusion) than ICA OR.     

Association between internal carotid artery morphometry and posterior communicating artery aneurysm

PURPOSE: The goal of this study was to directly measure the association between the internal carotid artery (ICA) morphometry and the presence of ICA-posterior communicating artery (PCOM) aneurysm. MATERIALS AND METHODS: The authors intraoperatively measured the length of the supraclinoid ICA because it is impossible to radiologically determine the exact location of the anterior clinoid process. We used an image analyzer with a CT angiogram to measure the angle between the skull midline and the terminal segment of the ICA (ICA angle), as well as the diameter of the ICA. The lengths and diameters of the supraclinoid ICA and the ICA angle were compared among PCOM aneurysms, anterior communicating artery (ACOM) aneurysms, and middle cerebral artery (MCA) bifurcation aneurysms (n=27 each). Additionally, the lengths and the diameters of M1 and A1 were compared for each aneurysm. RESULTS: The lengths of the supraclinoid ICA were 11.9+/-2.3 mm. The lengths of the supraclinoid ICA in patients with ICA-PCOM aneurysms (9.7+/-2.8 mm) were shorter than those of patients with ACOM aneurysms (13.8+/-2.2 mm, Student's t-test, p<0.001) and with MCA bifurcation aneurysms (12.2+/-1.9 mm, Student's t-test, p<0.001). The diameters of the supraclinoid ICA and A1 in patients with ACOM aneurysms were larger than those in patients with MCA bifurcation aneurysms (Student's t-test, p<0.05). There were no significant differences in the lengths of M1 and A1, ICA angle, or diameter of M1 for each aneurysm. CONCLUSION: These results suggest that the relatively shorter length of the supraclinoid ICA may be a novel risk factor for the development of ICA-PCOM aneurysm with higher hemodynamic stress.     

The effect of blood pressure calibrations and transcranial Doppler signal loss on transfer function estimates of cerebral autoregulation

There are methodological concerns with combined use of transcranial Doppler (TCD) and Finapres to measure dynamic cerebral autoregulation. The Finapres calibration mechanism ("physiocal") causes interruptions to blood pressure recordings. Also, TCD is subject to signal loss due to probe movement. We assessed the effects of "physiocals" and TCD signal loss on transfer function estimates in recordings of 45 healthy subjects. We added artificial "physiocals" and removed sections of TCD signal from 5 min Finapres and TCD recordings. We also compared transfer function results from 5 min time series with time series as short as 1 min. Accurate transfer function estimates can be achieved in the 0.03-0.07 Hz band using beat-by-beat data with linear interpolation, while data loss is less than 10s. At frequencies between 0.07 and 0.5 Hz, transfer function estimates become unreliable with 5s of data loss every 50s. 2s data loss only affects frequency bands above 0.15Hz. Finally, accurate transfer function assessment of autoregulatory function can be achieved from time series as short as 1min, although gain and coherence tend to be overestimated at higher frequencies.     

Development of methods to analyse transcranial Doppler ultrasound signals recorded in microgravity

During space flights, several clinical syndromes may be the result of changes in cerebral circulation. The purpose of the paper is to describe the development and initial evaluation of a system for recording, processing and displaying transcranial Doppler ultrasound (TCD) waveforms from the middle cerebral artery (MCA) in microgravity. Volunteers were repeatedly subjected to 15–20 s intervals of microgravity (‘near zero gravity’) during flights on the KC-135 military aircraft. Continuous TCD recordings from the MCA were stored on magnetic tape. The paper describes the system that was developed to digitise the Doppler ultrasound data and markers that corresponded to the various levels of microgravity, obtain the maximum and mean Doppler waveforms, identify the waveforms and quantify them. The results demonstrate the feasibility of making TCD recordings in a microgravity environment and illustrate excellent performance of the system and its ease of operation. Quantitative waveform analysis of the recordings from the first subject studied in the supine position showed statistically significant changes in MCA velocity waveforms during microgravity.     

新生儿缺氧缺血性脑病的经颅多普勒动态变化及临床意义

目的：研究新生儿缺氧缺血性脑病(HIE)的脑血流动力学的动态改变。方法：应用经颅多普勒(TCD)对89例HIE患儿及55例健康新生儿进行动态检查，并结合临床进行分析。结果：健康新生儿的大脑中动脉／颈内动脉流速比值(M／I)在0．9～1．2之间，轻度HIE的M／I在1．2～1．5之间；中重度HIE的M／I一般在1．8以上，其中M／I超过3．6以上者多死亡。结论：M／I与HIE临床有密切相关性，是HIE分度及预后估计的重要指标。     

实验性大鼠脑血管痉挛动物模型制备

目的探索实验性SD大鼠蛛网膜下隙出血（SAH）脑血管痉挛模型制备方法。方法尾动脉取血,立体定位仪下枕大池二次注血,印度墨水灌注测量大脑中动脉、颈内动脉和基底动脉直径,Morris水迷宫行为学测试,测定血中内皮素-1、一氧化氮合酶含量。结果 SAH组脑血管明显变细,Morris水迷宫显示有学习记忆能力减退,大脑中动脉、颈内动脉和基底动脉直径分别为（169.33±8.67）mm、（227.33±14.25）mm、（226.33±5.99）mm;内皮素-1和一氧化氮合酶分别为（214.36±10.49）g/L、（211.15±16.99）U/mL,与对照组比较有统计学差异。结论本实验方法能够制备蛛网膜下隙出血后脑血管痉挛模型。     

Real-time continuous neuromonitoring combines transcranial cerebral Doppler with near-infrared spectroscopy cerebral oxygen saturation during total aortic arch replacement procedure: a pilot study

The purpose of this investigation was to use combined transcranial cerebral Doppler (TCD) and near-infrared spectroscopy cerebral oxygen saturation (NIRS) during total aortic arch replacement (TAAR) to monitor middle cerebral artery blood flow velocity and regional cerebral oximetry (rSO(2)) changes to provide a clinical basis for protective measures that may decrease injury of the central nervous system. Consecutive 12 adult patients underwent deep hypothermic circulatory arrest (DHCA) and antegrade selective cerebral perfusion (ASCP) during TAAR. A TCD probe was placed at the temporal windows after induction of anesthesia and the NIRS probe placed on the forehead of patients to collect perioperative, intraoperative, and postoperative hemodynamic parameters, and cerebral blood flow (CBF) and rSO(2) during cardiopulmonary bypass (CPB). In this retrospective case series, all patients survived, and there were no postoperative neurologic complications. There was no significant correlation between the mean arterial pressure and rSO(2). The middle cerebral artery mean velocity (VmMCA) and rSO(2) were significantly correlated, and main pump flow significantly correlated with rSO(2). After ASCP, VmMCA, rSO(2), and venous oxygen saturation were significantly lower than before ASCP, but VmMCA and rSO(2) returned to pre-CPB levels postoperatively. After off pump, the flow of ASCP showed a significant positive correlation with VmMCA and rSO(2). During DHCA when ASCP flow was lower than 5 ml/kg/min, TCD could not detect the MCA blood flow signal. When the flow of ASCP was above keeping around 10 ml/kg/min, MCA CBF velocity was maintained and rSO(2) > 45%. The combination of TCD and NIRS can be effective in monitoring brain function during DHCA with ASCP and may provide a guide for decreasing brain injury during the TAAR procedure.     

TCD对行开颅去骨瓣减压术患者的诊疗指导价值

目的：采用经颅多普勒超声(trans-cranial Doppler,TCD)探究行开颅去骨瓣减压术的重度颅脑损伤患者围手术期血流动力学改变与其预后相关性。方法：选取100例于2012年9月至2015年9月入我院神经外科诊治的重度颅脑损伤[格拉斯哥昏迷评分(Glasgow coma scale,GCS)<8分]患者,采用TCD监测患者术前、术后双侧大脑中动脉(middle cerebral artery,MCA)和颈内动脉颅外段(extracranial internal carotid artery,ICAex)血流动力学参数,并比较差异是否具有统计学意义。结果：相比于术前,患者术后双侧MCA和ICAex平均流速(Vm)显著提高(P<0.01),其中手术侧Vm上升更明显。相比于术前,患者术后搏动指数(pulse index,PI)显著下降,且手术侧下降更为明显。患者术后频谱形态改变为高血流低阻力型。结论：应用TCD能很好地检测行开颅去骨瓣减压术重度颅脑损伤患者围手术期血流动力学改变,且患者颅内血流动力学改变对预后判断具有重要意义。     

Lacunar infarction in type 2 diabetes is associated with an elevated intracranial arterial pulsatility index

PURPOSE: The arterial pulsatility index (PI) is measured by transcranial Doppler ultrasonography (TCD) and is postulated to reflect the vascular resistance distal to the artery being examined. An increased PI of the intracranial artery is often reported with diabetes mellitus (DM), old age, hypertension, intracranial hypertension, vascular dementia, and small artery disease. Microvascular complication of DM, which may contribute to cerebral infarction, involves the small perforating artery and may influence the PI of the proximal artery. MATERIALS AND METHODS: We performed a TCD examination in patients with type 2 DM with acute lacunar infarction (DML, n=35), type 2 DM without cerebral infarction (DMO, n=69), and in control cases with no DM or cerebral infarction (control group, n=41). We then compared the TCD findings among these groups. RESULTS: The PI was significantly higher in the DML and DMO groups than in the control group (1.05, 0.93, 0.73. respectively, for the right middle cerebral artery; 1.04, 0.90, 0.73, respectively, for the left middle cerebral artery; 0.97, 0.89, 0.70, respectively, for the basilar artery). The PI was also significantly higher in the DML group than in the DMO group for both middle cerebral arteries. The flow velocity was comparable among the three groups. CONCLUSION: The elevated PI of the intracranial arteries may reflect diabetic cerebral microvascular complications. The PI measurement using TCD may be a useful predictor of lacunar infarction in type 2 DM patients.