Nearly automated analysis of coronary Doppler flow velocity from transthoracic ultrasound images: validation with manual tracings

Coronary flow velocity reserve is obtained by manual tracings of transthoracic coronary Doppler flow velocity profiles as the ratio of stress versus baseline diastolic peak velocities. This approach introduces subjectivity in the measurements and limits the information which could be exploited from the Doppler velocity profile. Accordingly, our goals were to develop a technique for nearly automated detection of Doppler coronary flow velocity profile, and automatically compute both conventional and additional amplitude, derivative and temporal parameters, and validate it with manual tracings. A total of 100 patients (17 normals, 15 patients with severe coronary stenosis, 41 with connective tissue disease and 27 with diabetes mellitus) were studied. Linear correlation and Bland–Altman analyses showed that the proposed method was highly accurate and repeatable compared to the manual measurements. Comparison between groups evidenced significant differences in some of the automated parameters, thus representing potentially additional indices useful for the noninvasive diagnosis of microcirculatory or coronary artery disease.     

Blood flow measurement during exercise in sheep using Doppler ultrasonic method

Continuous recording of blood flow to the coronary, renal and hindlimb vascular beds of sheep has been carried out using flow probes implanted around the major vessels supplying these regions. Blood flow has been recorded at rest, with the sheep running at speeds of 1–16 kmh⁻¹ on a treadmill, and during the recovery period. A Doppler flowmeter has been developed to facilitate compatibility with existing equipment, to enable reliable reproduction of the unit and to keep costs to a minimum. To minimize interference accompanying the violent movements of exercise great care must be taken with the electrical connections and flow probes require streamlining to facilitate implantation. Blood flow to both hindlimb and coronary vascular beds increased during exercise while that to the renal vascular bed did not change. Thus continuous recording with the Doppler ultrasonic flowmeter can be utilised during all phases of exercise, unlike other methods such as the use of radioactive microspheres which provides only point estimations and has limited application for repeated measurement.     

Doppler colour flow analysis of uterine and ovarian arteries prior to and after surgery for tubal sterilization: a prospective study

Female sterilization by tubal ligation is a very common methodof birth control. A relationship between tubal sterilizationand subsequent development of menstrual disorders has been describedin the literature but a biological mechanism explaining suchan association has not yet been demonstrated. The aim of thisstudy was to evaluate the influence of tubal ligation by thePomeroy technique on ovarian and uterine artery blood flow usingpre- and post-surgical Doppler assessments. We studied prospectively20 patients undergoing laparotomy for tubal ligation. All patientshad a Doppler blood flow assessment before and after surgery,conducted in the mid-foUicular phase of their cycle. The pulsatilityindex (PI) of the right uterine artery ranged from 1.44 to 3.86(mean 2.23) when measured prior to surgery and from 136 to 2.85(mean 2.13) when measured after surgery. In the left uterineartery, the PI ranged from 1.67 to 3.17 (mean 2.17) and from1.69 to 2.88 (mean 2.22) before and after surgery respectively.The difference was not statistically significant The PI of theright ovarian artery ranged from 138 to 3.48 (mean 2.41) priorto surgery and from 1.48 to 3.23 (mean 2.29) after surgery.In the left ovarian artery, the PI ranged from 1.36 to 3.62(mean 234) and from 1.85 to 4.00 (mean 2.61) before and aftersurgery respectively. Again, the difference was not statisticallysignificant Our results suggest that tubal sterilization performedby Pomeroy‘s technique does not induce immediate alterationsin the vascular flow of either ovarian or uterine arteries.     

Design of a continuous-wave Doppler ultrasonic flowmeter for perivascular application

The paper details the specification of an ultrasonic Doppler flowmeter intended for perivascular application and describes the elements of the design of an ultrasonic blood flow transducer. An optimised design is outlined for probes to be used on vessels in the range 5–12 mm. The design is based on the use of continuous-wave Doppler techniques and incorporates a novel polymer ultrasonic couplant. A constrained jet technique is used to test the performance of the probe in vitro and the results indicate that in use velocity profile effects are likely to lead to sensitivity changes of only 3 per cent. A companion paper details the design and performance of the electronic processing system needed for the complete flowmeter.     

Brachial arterial blood flow during static handgrip exercise of short duration at varying intensities studied by a Doppler ultrasound method

The purpose of this study was to determine forearm blood flow changes during static handgrip exercise at different intensities in relation to heart rate and blood pressure. Seven active women performed static handgrip exercise at intensities of 10, 30, 50 and 70% maximum voluntary contraction (MVC) in a supine position for 1 min. During exercise at different intensities, the brachial arterial blood flow (Doppler ultrasound method), calculated from vessel diameter, flow velocity and heart rate (measured by ECG), increased to a similar level (137.3 ± 20.2 – 160.9 ± 26.1 mL min^?1) from pre-exercise control value (87.5 ± 14.1 mL min^?1). These increases at the lower intensities were attributable to increased in-flow during one cardiac cycle, whereas at the higher intensities, they were due to increased heart rate. Both systolic and diastolic blood pressure (Finapres) changes increased from 10% MVC (16.1 ± 3.4, 9.0 ± 1.7 mmHg) up to 50% MVC (33.8 ± 6.7, 25.0 ± 4.9 mmHg), but were disproportionately more elevated at 70% MVC (46.1 ± 7.9, 42.9 ± 8.9 mmHg), suggesting neural vasoconstriction had occurred. Immediate post-exercise hyperaemia, used as an indicator of poor blood supply, became greater as the exercise intensity increased. These results suggest that the brachial arterial blood flow was maintained at a similar level during 60-s static handgrip exercise at different intensities by elevating the blood pressure and heart rate, which probably counteracted the increased intramuscular pressure and neural vasoconstriction occurring at the higher exercise intensity. The magnitude of the post-exercise hyperemic response increased as exercise level increased despite increased blood flow to the arm during exercise. This suggests a worsening imbalance in oxygen delivery in forearm muscles at higher levels of exercise.     

Feature discovery and classification of Doppler umbilical artery blood flow velocity waveforms

Doppler umbilical artery blood flow velocity waveform measurements are used in perinatal surveillance for the evaluation of fetal condition. There is an ongoing debate on the predictive value of Doppler measurements concerning the critical effect of the selection of parameters for the interpretation of Doppler waveforms. In this paper, we describe how neural network methods can be used both to discover relevant classification features and subsequently to classify Doppler umbilical artery blood flow velocity waveforms. Results obtained from 199 normal and high risk patients' umbilical artery waveforms highlighted a classification concordance varying from 90 to 98% accuracy.     

Uterine artery Doppler velocimetry and the outcome of pregnancies resulting from ICSI.

BACKGROUND: An increased incidence of pregnancy complications following assisted reproduction has been reported. The use of uterine artery Doppler ultrasound may aid the prediction of such complications. METHODS: Doppler was performed at 18-24 weeks gestation in 114 singleton and 32 twin pregnancies after intracytoplasmic sperm injection (ICSI) and compared with a control group matched for age, parity and plurality. Outcome variables included gestational age at delivery, prematurity, preterm premature rupture of membrane (PPROM), birth weight, birth weight discordance of >20% in twins, small for gestational age (SGA), mode of delivery, development of pre-eclampsia and placental abruption. RESULTS: Compared with the controls, there were no significant differences concerning uterine Doppler parameters, pregnancy complications and the neonatal outcome, either in singleton or in twin pregnancies. According to Doppler results and/or risk factors by medical history, 42% of singleton ICSI and 39% of spontaneous singleton pregnancies were considered as high risk. In singletons, abnormal Doppler findings were associated with pre-eclampsia in 22% and SGA in 26% of ICSI patients, compared with 33 and 21% in controls; in contrast, 0 and 10% in ICSI and 3 and 6% in controls showed these complications but no risk factors respectively. No correlation was found between PPROM, prematurity, the rate of Caesarean section and pathological Doppler results. CONCLUSIONS: Uterine Doppler examination holds the potential to identify patients with an increased risk for developing pregnancy complications. According to our results, this risk is not elevated after ICSI treatment, therefore the decision of offering an intensified antenatal care should be based on the results of Doppler examination or risks by medical history rather than the mode of conception.     

Design of a continuous-wave Doppler ultrasonic flowmeter for perivascular application

The paper details the design of the signal processing system of an ultrasonic Doppler flowmeter intended for perivascular application. The system is designed to work in conjunction with a transducer system described in an earlier paper, in a range of vessels varying from 5 mm to 12 mm. The system incorporates conventional quadrature processing for directional discrimination and uses phaselocked loop technology to extract signals corresponding to the instantaneous mean frequency (velocity equivalent). The use of a PLL also permits the extraction of a quasi-spectral analysis signal. The baseline stability of the Doppler system is enhanced by the use of an auto-zeroing system which enables the system to resolve Doppler shifts down to 20Hz. Testing of the complete transducer/signal processor system in a hydraulic rig demonstrates the ability of the flowmeter to accurately measure both steady and pulsatile flow.     

The local progestational effect of the levonorgestrel-releasing intrauterine system: a sonographic and Doppler flow study

BACKGROUND: We aimed to evaluate the effect of the levonorgestrel-releasing intrauterine system (LNG-IUS) on the uterine vasculature and the endometrium. METHODS: The study was a prospective controlled study evaluating the local effects of LNG-IUS compared with the copper intrauterine device (IUD). Forty-seven women carrying LNG-IUS (group A) were compared with 35 women carrying copper IUD in a control group (group B). Clinical measures of menstrual bleeding, endometrial thickness and Doppler flow of the cervical branch of the uterine artery and spiral artery were evaluated and compared between the two groups. RESULTS: Doppler flow in the cervical branch of the uterine artery did not reveal any changes between the groups (resistance index = 0.6 +/- 0.01 in both groups). Endometrial width was significantly thinner in group A (4.1 +/- 0.2 mm) compared with group B (7.3 +/- 0.2 mm) (P < 0.0001). Subendometrial flow in the spiral artery was significantly reduced in 35 women of group A (75%) and in none of group B (P < 0.0001). CONCLUSIONS: The present study offers an explanation for the oligomenorrhoea in LNG-IUS users, i.e. a local progestational effect on the endometrium with no change in the blood flow in the uterine artery. This should be presented to the women in the pre-contraceptive counselling in order to lessen the discontinuation rate.     

Visually evoked blood flow responses and interaction with dynamic cerebral autoregulation: Correction for blood pressure variation

Visually evoked flow responses recorded using transcranial Doppler ultrasonography are often quantified using a dynamic model of neurovascular coupling. The evoked flow response is seen as the model's response to a visual step input stimulus. However, the continuously active process of dynamic cerebral autoregulation (dCA) compensating cerebral blood flow for blood pressure fluctuations may induce changes of cerebral blood flow velocity (CBFV) as well. The effect of blood pressure variability on the flow response is evaluated by separately modeling the dCA-induced effects of beat-to-beat measured blood pressure related CBFV changes.Parameters of 71 subjects are estimated using an existing, well-known second order dynamic neurovascular coupling model proposed by Rosengarten et al. [1], and a new model extending the existing model with a CBFV contributing component as the output of a dCA model driven by blood pressure as input.Both models were evaluated for mean and systolic CBFV responses. The model-to-data fit errors of mean and systolic blood pressure for the new model were significantly lower compared to the existing model: mean: 0.8% ± 0.6 vs. 2.4% ± 2.8, p < 0.001; systolic: 1.5% ± 1.2 vs. 2.2% ± 2.6, p < 0.001. The confidence bounds of all estimated neurovascular coupling model parameters were significantly (p < 0.005) narrowed for the new model.In conclusion, blood pressure correction of visual evoked flow responses by including cerebral autoregulation in model fitting of averaged responses results in significantly lower fit errors and by that in more reliable model parameter estimation. Blood pressure correction is more effective when mean instead of systolic CBFV responses are used. Measurement and quantification of neurovascular coupling should include beat-to-beat blood pressure measurement.     

Influence of posture on middle cerebral artery mean flow velocity in humans

We determined middle cerebral artery, common carotid artery and temporal superficial artery Doppler derived flow velocities in ten subjects for 10 min after change in posture. Maximal changes were observed after about 3 min. The 10° head-down tilt position increased blood velocities in the common carotid artery by 13% (SD 4)% (P < 0.001), in the middle cerebral artery by,6% (SD 3)% (P < 0.001) and in the superficial temporal artery by 70% (SD 26)% (P < 0.001). In the standing position, there was an 18% (SD 9)% (P < 0.001) decrease in the common carotid blood velocities, with 14% (SD 6)% (P < 0.001) and 53% (SD 23)% (P < 0.001) reductions in the middle cerebral and superficial temporal artery velocities, respectively. At 9 min after the changes in posture, velocities in the middle cerebral artery were at the value of supine rest, whereas the common carotid blood velocity was not completely restored and deviations in the temporal artery velocity persisted. The data would suggest that cerebral blood flow is regulated with some delay and that such regulation is partially reflected in the common artery blood flow, since changes in a branch of the external carotid artery flow velocity remained.     

川崎病患儿冠状动脉血流储备测定与影像形态学诊断的对照研究

目的评价持续冠状动脉病变对川崎病（KD）患儿冠状动脉血液动力学的影响,探讨冠状动脉血流储备（CFR）检测在KD患儿冠状动脉病变远期随访中的应用价值。方法选择因胸痛、心悸以及各类偶发早搏的患儿为对照组,KD并发持续左冠状动脉病变患儿为KD组,均予以ATP160μg·kg^-1·min^-1持续静脉注射,共6min。运用经胸多普勒超声心动图（TTDE）检测冠状动脉左前降支（LAD）在ATP注射前后的舒张期峰值流速（PDV）及平均流速（MDV）,并通过计算比值得出相应CFR（PDV）和CFR（MDV）值。结果对照组纳入25例,CFR（PDV）和CFR（MDV）值均与年龄呈显著正相关（r=0.596,0.591,P=0.002,0.002）;〈2岁、-8岁和〉8岁组的CFR（PDV）95%参考值范围分别为≥1.22、≥1.94和≥2.22。KD组纳入8例,静息状态下PDV和MDV值分别为（50.0±15.07）cm.s^-1和（35.16±11.52）cm.s^-1,显著高于对照组（P=0.004,0.015）;而CFR（PDV）和CFR（MDV）值明显降低,分别为（1.67±0.38）cm.s^-1和（1.69±0.47）cm.s^-1（P=0.002,0.018）。与对照组比较,KD组7/8例（87.5%）患儿CFR（PDV）值显著降低。结论持续冠状动脉病变可导致KD患儿CFR值显著降低,TTDE检测患儿CFR具无创、安全和便捷的优点,对于KD冠状动脉病变的长期随访与临床诊断治疗策略的选择具有指导意义。     

Colour Doppler indices of follicular blood flow as predictors of pregnancy after in-vitro fertilization and embryo transfer.

Peak systolic velocity (PSV) of individual follicles has been correlated with oocyte recovery, fertilization rate and embryo quality [in women undergoing in-vitro fertilization (IVF) and embryo transfer]. The present study assessed the role of quantitative and qualitative indices of follicular vascularity in predicting pregnancy after IVF and embryo transfer. A total of 106 women undergoing IVF treatment for infertility who were considered to be at risk of failure (>37 years of age, history of low response to gonadotrophin stimulation, or multiple failed IVF cycles) constituted the study group. PSV was measured from the three largest follicles on both the right and left ovaries on the day of human chorionic gonadotrophin (HCG) administration using an Acuson Sequoia with a 4-8 MHz transvaginal probe. The quality of follicular flow was graded from 1 to 4 according to the amount of visible colour flow around the follicle (grade 1 when one-quarter of the follicle, grade 2 when one-half, grade 3 when three-quarters, and grade 4 when the entire follicle was surrounded by colour). Clinical pregnancies resulted in 11 (10%) of the 106 high-risk women. Women who had PSV >/= 10 cm/s in at least one follicle on the day of HCG administration more often became pregnant than those with PSV <10 cm/s (P = 0.05). All pregnancies occurred in women with grade 3 or 4 follicular blood flow. Qualitative as well as quantitative measurements of follicular flow predict pregnancy after IVF and embryo transfer.     

多普勒超声在全动脉化冠状动脉旁路移植术前桥血管筛查中的应用价值

目的:探讨多普勒超声在全动脉化冠状动脉旁路移植(CABG)术前评估桡动脉及左侧乳内动脉的临床应用价值。方法:回顾性研究。纳入2018年1月—2020年1月蚌埠医学院第一附属医院收治的60例冠心病患者,其中男34例、女26例,年龄44～76岁。患者术前均使用多普勒超声检查左侧乳内动脉及双侧桡动脉。(1)分别采用超声和Al...     

多普勒超声观察创伤性寰枢椎不稳手术前后椎动脉血流的变化

目的探讨创伤性寰枢椎不稳患者内固定手术前后椎动脉血流的变化。方法32例创伤性寰枢椎不稳患者,其中男性22例,女性10例;年龄22～57岁,平均年龄38岁。手术前及内固定术后,均应用彩色多普勒超声测量颈椎1、2间和颈椎5、6间椎动脉血流速度、阻力指数。并对检查结果进行对比分析。结果32例创伤性寰枢椎不稳患者术前椎动脉血流39侧异常,25侧正常。内固定术后39侧异常者中35侧恢复正常,4侧无变化,3侧术前正常变为术后异常。结论创伤性寰枢椎不稳可导致椎动脉血流变化,手术复位内固定后增加了寰枢椎稳定性,可改善椎动脉血液供应。     

The effect of distension of the stomach on coronary blood flow in anaesthetized pigs

The present study was undertaken in anaesthetized pigs to determine whether distension of the stomach reflexly affects coronary blood flow. Experiments were performed on 17 pigs anaesthetized with ketamine and sodium pentobarbitone and artificially ventilated. Coronary blood flow was measured with an electromagnetic flowmeter positioned around the origin of the left circumflex coronary artery. The stomach was distended by injecting 0.81 warm Ringer solution into a balloon positioned within the stomach (mean gastric transmural pressure of about 13 mm Hg). Changes in aortic blood pressure and heart rate were prevented by a pressurized reservoir connected to the left femoral artery and by atrial pacing respectively. Distension of the stomach always caused a decrease in mean coronary blood flow. In five pigs, the magnitude of the decrease in coronary blood flow was graded by step increments in the gastric distending volume from 0.6 l to 1 l. The response of coronary blood flow was not affected by the administration of atropine (12 pigs), while it was abolished by the administration of bretylium tosylate (eight pigs) and by bilateral vagotomy (eight pigs; four cervical, four subdiaphragmatic vagotomy). These results show that innocuous distension of the stomach in anaesthetized pigs reflexly decreases coronary blood flow. This reflex response is mediated by sympathetic effects and its afferent limb involves the vagal nerves.     

Doppler ultrasound investigation of uterine and ovarian blood flow in infertility and early pregnancy

This review describes the current use of Doppler ultrasoundto examine blood flow in the uterus and ovaries in infertilepatients and during early pregnancy. The basics of Doppler ultrasoundand the different methods of measuring blood flow are discussedfrom the viewpoint of the clinician who may be unfamiliar withDoppler physics and terminology. Normal values in the menstrualcycle and the relationship of uterine and ovarian blood flowto infertility and to implantation following in-vitro fertilizationare presented. Normal values for uterine blood flow in the first16 weeks of pregnancy and the effect of sex steroids and ovulationinduction on their values are described. The possible relationshipof defective uterine blood flow, and the effect of drugs areexplored. The findings of this review indicate that Dopplerblood flow studies may provide significant information aboutpossible causes of some disorders of infertility and early pregnancyand methods of treatment for the same.     

PET tracers and techniques for measuring myocardial blood flow in patients with coronary artery disease

Assessment of the relative distribution of myocardial flow with myocardial perfusion imaging （MPI） is meth- odologically limited to predict the presence or absence of flow-limited coronary artery disease （CAD）. This limi- tation may often occur, when obstructive lesions involve multiple epicardial coronary arteries or disease-related disturbances of the coronary circulation coexist at the microvascular level. Non-invasive assessment of myocar- dial blood flow in absolute units with position emission tomography （PET） has been positioned as the solution to improve CAD diagnosis and prediction of patient outcomes associated with risks for cardiac events. This article reviews technical and clinical aspects of myocardial blood flow quantitation with PET and discusses the practical consideration of this approach toward worldwide clinical utilization.