Significance of an absent or reversed end diastolic flow in Doppler umbilical artery waveforms

The outcome of nine fetuses in whom Doppler umbilical arterial velocity-time waveforms showed absence or reversal of flow in end diastole was presented. Eight of the nine resulted in either intrauterine or neonatal death. Progressive deleterious changes in the waveforms were evident in three fetuses who had serial evaluation. The remaining infant survived when delivery was expected 2 days later. Our data have indicated that the demonstration of an absent or reversed flow in end diastole in the umbilical arteries carries with it a very specific indication of serious fetal compromise and the need for immediate delivery, although the prognosis of a normal neonatal survival remains guarded.     

First-trimester reversed end-diastolic flow in the umbilical artery is not always an ominous sign.

We report five cases of first-trimester reversed end-diastolic flow in the umbilical artery. Diagnoses were performed between 8 and 12 gestational weeks. All but one case appeared as a transient early finding. Second-trimester fetal demise occurred in two cases. One case delivered at 32 weeks with severe growth restriction but recovered well. The other two cases had a good pregnancy outcome. Our experience suggests that this early Doppler finding is not always an ominous sign.     

Biofeedback-assisted relaxation in migraine headache: relationship to cerebral blood flow velocity in the middle cerebral artery

OBJECTIVE: To determine if migraineurs with aura respond differently to biofeedback/relaxation than those without aura and, if so, whether the variability in outcome can be explained by blood flow velocity. Background.-The relationship between cerebral blood flow velocity and treatment response to biofeedback/relaxation in migraine with and without aura is uncertain. METHOD: Twenty migraineurs underwent 12 sessions of biofeedback/relaxation therapy, while 20 controls simply were told to relax on their own. Cerebral blood flow velocity was measured bilaterally in the middle cerebral artery with transcranial Doppler. RESULTS: The biofeedback group showed significant (P <.05) reductions in pain, depression, and anxiety compared to the control group. Patients with and without aura did equally well. There were significant (P <.05) left to right blood flow velocity differences only in the migraine with aura group. Maximum blood flow velocities were significantly higher (P <.05) in the migraine with aura group than in the cohort without aura. There was an inverse correlation between indicators of anxiety and blood flow velocity, perhaps related to hyperventilation-induced constriction in the small vessels distal to the middle cerebral artery. CONCLUSION: The positive treatment response to biofeedback/relaxation in migraine headache is not related to presence of aura, nor to changes in blood flow velocity, but may be associated with reduction in anxiety and depression.     

Increased middle cerebral artery blood flow impedance in fetal subdural hematoma.

This case describes the prenatal diagnosis at 30 weeks' gestation of a posterior fossa subdural hematoma. Doppler velocimetry studies of the middle cerebral artery at that time showed an abnormally high resistance pattern with reverse end-diastolic flow. Ultrasonic assessment of the fetus indicated that there was associated quadriplegia. No cause for the lesion was demonstrated. A fetal blood sample, obtained by cordocentesis, revealed a normal karyotype. Fetal blood gas analysis was also normal. The pregnancy was terminated at the parents' request.     

大鼠大脑中动脉局灶性脑缺血局部脑血流动态观察

目的:动态观察了鼠须栓塞大鼠大脑中动脉局灶性脑缺血模型局部脑血流(regionalcerebralbloodflow,rCBF)变化与时间的关系。方法:雄性Wistar大鼠12只,体重250～350g。根据缺血时间分为缺血0.5,1.0,1.5,2.0,3.0,6.0,9.0,12.0h。采用鼠须栓塞法制做大鼠大脑中动脉局灶性脑缺血模型,氢清除法测定大鼠大脑中动脉供血中心区缺血各时点大脑皮层rCBF变化。结果:12h组2只动物因吸入氢气过量致窒息死亡,其他全部动物均在规定时间内完成rCBF测定。缺血前rCBF为(149.77±6.76)ml/(100g·min),缺血30min下降至(106.94±7.21)ml/(100g·min),缺血6h降至(12.73±1.66)ml/(100g·min)。除缺血90min和2h点rCBF无统计学显著差异外,其它各时间点rCBF均存在显著差异(P<0.01)。rCBF随时间渐趋下降,回归分析示与时间呈显著相关(r=-0.77,P=0.024)。至缺血12hrCBF不能测出。结论:该研究为扩大治疗时间窗的保护性治疗提供了脑血流变化的理论依据。     

全心舒张末容量作为判定心脏前负荷指标在犬失血性休克模型中的研究

目的 评估通过热稀释法测量全心舒张末容量作为心脏前负荷指标的准确性和实用性。方法 通过右心漂浮导管和脉搏诱导持续心输出量测量法（PICCO）在20只犬失血性休克模型制作前后，分别给予生理盐水（NS）、贺斯溶液（HES）、高渗盐溶液（HS）以及高渗高张溶液（HSS）对失血性休克模型进行容量复苏，测量容量复苏前后血液动力学，比较全心舒张末容量（GEDV）、中心静脉压（CVP）、肺动脉楔压（PAWP）在判定前负荷中的作用。结果 容量复苏前后血液动力学指标有显著变化（P〈0．05），全心舒张末容量指数（GEDVI）变化与每搏输出指数（SVI）和心输出量指数（CI）的变化呈正相关。中心静脉压和肺动脉楔压的变化与每搏输出指数（SVI）无关。结论 在失血性休克犬模型中，与压力指标（中心静脉压、肺动脉楔压）相比较，全心舒张末容量（GEDV）能够更好地反映心脏前负荷。     

胎儿三尖瓣反流与脐动脉及大脑中动脉超声血流频谱的相关性分析

目的观察胎儿三尖瓣反流时脐动脉和大脑中动脉（MCA）血流频谱的变化,探讨不同程度胎儿三尖瓣反流对脐动脉和MCA血流频谱的影响。方法测量三尖瓣反流时胎儿脐动脉和MCA的血流频谱,分析胎儿不同程度三尖瓣反流时脐动脉和MCA频谱的变化情况,并与对照组比较分析。结果三尖瓣I、Ⅱ级反流时,胎儿脐动脉和MCA血流频谱与对照组比较差异无统计学意义。三尖瓣Ⅲ、Ⅳ级反流时,脐动脉阻力指数、搏动指数及收缩期峰值血流速度与舒张期血流速度比值（s／D）均增高,MCA阻力指数、搏动指数及s／D均降低,与对照组比较差异有统计学意义（P〈0．05）。结论三尖瓣I、Ⅱ级反流对胎盘功能影响不大,宫内缺氧不明显;中重度三尖瓣关闭不全则会影响胎盘功能,进而引起胎儿官内缺氧,产生脑保护效应。     

Comparison of different reference values of fetal blood flow velocity in the middle cerebral artery for predicting fetal anemia.

OBJECTIVES: To compare different normal reference ranges of fetal blood flow velocity in the middle cerebral artery for predicting fetal anemia. METHODS: Eight reference ranges of either middle cerebral artery peak or time-averaged mean velocities were compared using the area under the receiver-operating characteristics (ROC) curve for 113 fetal blood samples from 60 women at risk of fetal red blood cell alloimmunization. RESULTS: The areas under the ROC curves of the different ranges were not significantly different but there were marked differences in sensitivity (range, 7.14-91.78%) and specificity (range, 31.25-96.88%) with the currently used cut-offs. Except for Mari's range, the best theoretical cut-offs, defined as those having the best sensitivity with the best specificity, differed from those in current use, especially when using time-averaged mean velocity. CONCLUSIONS: Any of the previously reported reference ranges perform well in the non-invasive prediction of fetal anemia. However, with the exception of Mari's curve, the currently employed cut-offs for predicting fetal anemia should be changed, some of them markedly, in order to provide reliable support for clinical decisions.     

Modulation of middle cerebral artery flow velocity waveforms by breathing movements in the normal term fetus

Breathing dependency of fetal middle cerebral artery flow velocities was studied in 10 normal pregnancies at term. Peak systolic, end-diastolic and time-averaged flow velocities and pulsatility index during fetal breathing were not significantly different from those observed during apnoea. However, the standard deviation for each flow velocity parameter was significantly increased during fetal breathing activity, indicating marked modulation of middle cerebral artery velocities.     

高血压患者冠状动脉血流储备下降对左室舒张功能减退的影响

目的 探讨血压控制达标的高血压患者冠状动脉血流储备（Coronary flow reserve, CFR）对左室舒张功能的影响。 方法 86例血压控制达标且经冠脉造影或冠脉CT检查证实冠脉狭窄<50%的高血压患者,行经胸多普勒超声心动图ATP负荷试验检测冠状动脉左前降支的CFR;测定ATP负荷前后左室舒张功能参数,包括舒张早期、舒张晚期二尖瓣血流速度（E、A）和左心室侧壁及间隔二尖瓣环舒张早期、舒张晚期运动速度（Em、Am）,分析CFR与左室舒张功能参数的关系。 结果 入组患者总体CFR为2.85±0.67,其中CFR<3者47人（54.65%）,CFR为2.35±0.40,CFR≥3者39人（45.35%）,CFR为3.45±0.36;CFR<3的患者CFR与ATP负荷后侧壁Em呈正相关（r=0.42,P=0.003）,多元线性回归分析显示CFR为ATP负荷后侧壁Em的独立影响因素（P=0.015）。 结论 血压控制达标且排除冠心病的高血压患者约50%存在冠脉微循环障碍;有微循环障碍的高血压患者CFR下降是左室舒张功能减退的独立影响因素。     

肝动脉舒张期血流在预测肝移植术后肝动脉血栓形成中的意义

目的 回顾性分析肝动脉舒张期异常血流状况在预测肝移植术后肝动脉血栓形成中是否有意义。方法 对2000年8月至2003年6月间，在我院接受原位肝移植术的54例术后可测及肝动脉信号患者的多普勒超声检查结果及其临床资料行回顾性分析。根据肝动脉舒张期的血流状况将探测结果分为3类：舒张期正向血流，舒张期反向血流和舒张期无血流信号。同时对所有病例的门静脉血流状况进行多普勒分析。结果 54例中12例出现舒张期异常血流，其中4例表现为舒张期反向血流，8例表现为舒张期无血流信号。12例中1例有肝动脉吻合口狭窄，无出现肝动脉血栓形成者。所有病例的门静脉血流未见异常。结论 肝移植术后早期肝动脉舒张期无血流或反向血流与肝动脉血栓形成之间没有相关性，肝动脉舒张期无血流或反向血流不能作为预测肝动脉血栓形成的判定指标。     

异丙酚复合瑞芬太尼全凭静脉麻醉对脑血流速率影响的分析

目的 观察异丙酚复合瑞芬太尼全凭静脉麻醉对脑血流速率的影响。方法 选择40例择期手术患者，麻醉诱导采用瑞芬太尼1μg/kg，异丙酚2．0mg／kg，司可林1．5mg／kg，气管插管成功后机械通气。微泵持续输注异丙酚4．0—6．0mg／kg·h，瑞芬太尼0．1～0．2μg/kg·min维持麻醉。采用经颅多普勒脑血流监测仪，分别于麻醉诱导前、静注瑞芬太尼后、静注异丙酚后、气管插管后、手术维持中，测定一侧大脑中动脉平均流速（Vm—MCA），同时监测记录MAP、HR的变化。结果 麻醉诱导后，MAP、Vm—MCA均低于诱导前水平（P〈0．05），气管插管后二者与诱导前水平无显著性差异（P〉0．05），术中Vm—MCA也低于诱导前水平（P〈0．05）。结论 异丙酚复合瑞芬太尼可降低脑血流量，适用于神经外科麻醉。     

Delayed onset of tricuspid valve flow in repaired tetralogy of Fallot: an additional mechanism of diastolic dysfunction and interventricular dyssynchrony

Background

Diastolic dysfunction of the right ventricle (RV) is common after repair of tetralogy of Fallot. While restrictive physiology in late diastole has been well known, dysfunction in early diastole has not been described. The present study sought to assess the prevalence and mechanism of early diastolic dysfunction of the RV defined as delayed onset of the tricuspid valve (TV) flow after TOF repair.

Methods

The study population consisted of 31 children with repaired TOF (mean age ± SD, 12.3 ± 4.1 years) who underwent postoperative cardiovascular magnetic resonance (CMR). The CMR protocol included simultaneous phase-contrast velocity mapping of the atrioventricular valves, which enabled direct comparison of the timing and patterns of tricuspid (TV) and mitral (MV) valve flow. The TV flow was defined to have delayed onset when its onset was > 20 ms later than the onset of the MV flow. The TV and MV flow from 14 normal children was used for comparison. The CMR results were correlated with the findings on echocardiography and electrocardiography.

Result

Delayed onset of the TV flow was observed in 16/31 patients and in none of the controls. The mean delay time was 64.81 ± 27.07 ms (8.7 ± 3.2% of R-R interval). The delay time correlated with the differences in duration of the TV and MV flow (55.94 ± 32.88 ms) (r = 0.90, p < 0.001). Delayed onset was associated with prolongation of the RV ejection time in 9 and delayed onset and cessation of the pulmonary arterial flow in 4. Delayed onset was not associated with timing changes in the pulmonary artery in 3. The patients with delayed onset showed reduced RV ejection fraction (p = 0.01). However, the two groups did not show significant differences in TV E/A ratio, ventricular end-diastolic volumes, left ventricular ejection fraction, pulmonary regurgitant fraction, heart rate, PR interval and QRS duration.

Conclusions

Early diastolic dysfunction with delayed onset of TV flow is common after TOF repair, and is associated with reduced RV ejection fraction. It is a further manifestation of interventricular dyssynchrony and represent an additional mechanism of ventricular diastolic dysfunction.     

Acceleration time in the fetal middle cerebral artery during the second half of pregnancy

We made a longitudinal ultrasonographic study of 33 healthy fetuses from 22 to 38 weeks of gestation to determine the acceleration time in the middle cerebral artery (ATMCA) and its relationship with fetal cardiac output. Doppler ultrasound (US) was performed by a single observer always using the same apparatus. The Doppler tracing was obtained with a sample volume of 1 mm; placement was on the anterior middle cerebral artery, as close as possible to the skullcap. The insonation angle was kept between 5 degrees and 19 degrees and the wall filter was adjusted to a frequency of 50 to 100 Hz. The ATMCA was 40 ms at 22 and 26 weeks, 50 ms at 30 and 34 weeks and 60 ms at the 38th week. There was a significant positive correlation between gestational age and ATMCA values (r=0.45, p<0.001). The ATMCA values became significantly higher than the initial values at the 30th week of gestation (p<0.05). The ATMCA values for normal fetuses could be compared with those obtained during high-risk pregnancies; this would be useful for the detection of fetal cardiac anomalies.     

Reversed diastolic flow in the uterine artery - a new Doppler finding related to placental insufficiency?

Increased uterine artery pulsatility and resistance indices with or without notching of the waveform have been associated with an increased risk of pre-eclampsia and fetal growth restriction. However, reversed diastolic flow in the uterine artery has not previously been reported. We present two high-risk obstetric cases complicated by severe placental insufficiency: pre-eclampsia followed by eclampsia in one case and intrauterine growth restriction with abnormal cardiotocography in the other. Doppler studies of the uterine arteries revealed reversed diastolic flow in both cases. The pathophysiology and potential implications are discussed.     

Color duplex sonography of occlusion of the common carotid artery with reversed flow in the extracranial internal carotid artery

In a small percentage of cases with an occluded common carotid artery (CCA), the patency of the arteries beyond the carotid bulb is preserved. Color duplex sonography is useful for assessing blood flow in these vessels. We present a case of retrograde flow in an internal carotid artery (ICA) with an occluded ipsilateral CCA identified using color duplex sonography in a 70-year-old man with diabetes and known atherosclerotic disease. Color duplex sonography revealed that the right CCA was totally occluded near its origin and that flow was re-established at the bulb. Flow in the right ICA was directed cephalad, with a low-frequency, damped waveform; flow in the right external carotid artery (ECA) was bidirectional, with increased reversed diastolic flow. Extensive atherosclerotic lesions were also found in the left side. Endarterectomy of the left carotid bifurcation was performed. Follow-up color duplex sonography 3 months later revealed a small increase of stenosis in the left CCA and mild stenosis in the left ICA. The right CCA remained occluded, but reversed flow with a high-resistance flow pattern was seen in the ipsilateral ICA that supplied the ECA, which had cephalad-directed flow.     

Variability of middle cerebral artery blood flow with hypercapnia in women

We examined the effect of euoxic hypercapnia on middle cerebral artery (MCA) blood flow velocity waveform parameters in pre- and postmenopausal women by exposing 24 healthy women (12 pre-, 12 postmenopausal) to hypercapnia for 20 min. MCA blood flow velocity was measured continuously by transcranial Doppler ultrasound. The data were run through an algorithm that detected the feature points of the waveforms and then analyzed for statistically significant group differences. The changes in mean blood flow velocity with euoxic hypercapnia were not significant between the two groups. However, certain feature points, particularly the velocity of the reflected shoulder (V_REFLEC), increased (89.4 ± 14.6 to 110.0 ± 20.5 cm/s and 102.3 ± 14.1 to 125.1 ± 14.9 cm/s from euoxic eucapnia to euoxic hypercapnia in pre- and postmenopausal women, respectively), as did the augmentation index (79.9 ± 10.4 to 85.9 ± 12.6% and 114.7 ± 12.8 to 119.0 ± 12.6%) and pulsatility index (0.86 ± 0.18 to 0.74 ± 0.15 and 0.71 ± 0.11 to 0.66 ± 0.11). Furthermore, while systolic peak velocity (V_SYS) was the highest point of the waveform in premenopausal women, V_REFLEC was the highest point for the postmenopausal cohort. The implications of this finding become obvious when calculating pulsatility index (PI), the values of which varied significantly for the postmenopausal women, depending on whether V_SYS or the absolute maximum was used. These findings suggest that hypercapnia increases blood flow velocity waveform reflections, and that PI calculations, particularly for older age groups, may need to be considered more carefully, since these reflections often exceed the systolic peak velocity. (E-mail: poulin@ucalgary.ca)     

数字减影血管造影对双侧大脑中动脉峰值流速的影响

目的 通过对数字减影血管造影(DSA)患者造影前后双侧大脑中动脉峰值流速改变的观察,探讨DSA对其的影响.方法 应用经颅多普勒超声(TCD)扫描仪动态监测DSA患者在各个时间点的双侧大脑中动脉峰值流速的改变.结果 注药侧、非注药侧两组之间的大脑中动脉峰值流速差异无统计学意义(P＞0.05);双侧大脑中动脉各个时点峰值流速存在波动,差异有统计学意义(P＜0.01),注药侧大脑中动脉峰值流速在注完药后迅速下降,从穿刺前30 s的(98.1±32.4) cm/s到(90.5±32.2) cm/s,随之上升,达到最高值(112.2±37.8) cm/s,随之逐渐下降,于拔鞘后恢复到注药前水平;非注药侧大脑中动脉峰值流速在注药前各时点无明显变化,但在注完药后峰值流速明显上升(110.9±42.0)cm/s,趋于平稳后开始下降,于拔鞘后恢复注药前水平;组间和不同时点的交互作用差异有统计学意义(P＜0.01),两者的变化趋势明显不同.结论 虽然DSA可能影响大脑中动脉峰值流速的变化,但其仍有较高的安全性.     

不同孕周脐带绕颈胎儿脐动脉及大脑中动脉血流参数的变化研究

目的：观察及探讨不同孕周脐带绕颈胎儿脐动脉及大脑中动脉血流参数的变化情况。方法：选取2010年10月—2013年5月于本院进行诊治的58例脐带绕颈胎儿为观察组,并以58例正常胎儿为对照组,将两组胎儿的脐动脉及大脑中动脉血流参数进行比较,并比较观察组中不同孕周胎儿的检测结果。结果：观察组胎儿的脐动脉及大脑中动脉PI、RI及S/D水平均高于对照组胎儿,而观察组中孕周37周以上者检测结果则高于28-36周的胎儿,P均〈0.05,均有显著性差异,同时分析检测指标与脐带绕颈的相关性。结论：脐带绕颈胎儿与正常胎儿脐动脉及大脑中动脉血流参数存在明显差异,且不同孕周脐带绕颈胎儿之间也存在显著差异,其与脐带绕颈有密切的关系,对于胎儿预后的价值较高。