Doppler assessment of pulmonary artery pressure in neonates at risk of chronic lung disease

AIM—To evaluate the pulmonary artery pressure (PAP) change in very low birthweight (VLBW) infants at risk of chronic lung disease (CLD).
METHODS—The time to peak velocity:right ventricular ejection time (TPV:RVET) ratio calculated from the pulmonary artery Doppler waveform, which is inversely related to PAP, was used. The TPV:RVET ratio was corrected for different heart rate (TPV:RVET(c)). Seventy three VLBW infants studied on days 1, 2, 3, 7, 14, 21 and 28 were enrolled for the analysis.
RESULTS—Twenty two infants developed CLD with a characteristic chest radiograph at day 28. Fifty one did not, of whom 17 were oxygen dependent on account of apnoea rather than respiratory disease, and 34 were non-oxygen dependent. The TPV:RVET(c) ratio rose progressively in all three groups over the first three days of life, suggesting a fall in PAP. In the oxygen and non-oxygen dependent groups, the mean (SD) ratio rose to 0.53 (0.09) and 0.57 (0.09), respectively, on day 7, then remained relatively constant thereafter. The CLD group rose more slowly after day 3 and had a significantly lower mean ratio from day 7 onwards compared with the other two groups (day 7: P<0.001, days 14-28: P<0.0001), and fell significantly from 0.47 (0.11) on day 7 to 0.41 (0.07) on day 28 (P=0.01), suggesting a progressive rise in PAP. The mean (SD) ratios at day 28 of all infants were: CLD group 0.41 (0.07); oxygen dependent group 0.66 (0.15); and the non-oxygen group 0.67 (0.11). The CLD group had a significantly lower ratio than the oxygen dependent group and the non-oxygen group (P<0.0001). Using the TPV:RVET(c) ratio of <0.46, infants at risk of developing CLD could be predicted on day 7 (predictive value 82.8%, sensitivity 54.5%, specificity 94.1%).
CONCLUSION—The non-invasive assessment of PAP using the TPV:RVET(c) ratio may be useful in the longitudinal monitoring of PAP change in VLBW infants, and for prediction of chronic lung disease.

     

Estimation of pulmonary artery pressure by ultrasound

Summary To determine the most reliable echocardiographic criteria of the pulmonary valve echo in predicting pulmonary artery (PA) pressures or PA resistance, 48 children, aged 6 months to 16 years with congenital (CHD) or rheumatic heart disease (RHD), were studied During routine heart catheterization, simultaneously recorded PA pressures and one-dimensional PA valve echograms were obtained. Echocardiographic measurements of the e–f and b–c slopes, the “a” dip, right ventricular (RV) and left ventricular (LV) systolic time intervals (STI; PEP = pre-ejection period; ET = ejection time), and their ratios were compared with PA systolic, diastolic, and mean pressures as well as with pulmonary arteriolar resistance (PAR) and the ratio PAR to systemic resistance (SR). The e–f slope and b–c slope correlated poorly with PA pressures and PAR. RVPEP/RVET ratio gave a good second-degree polynomial correlation with PA diastolic pressure, PAR and PAR/SR in CHD (r=.78, .79, .87). The correlation was better for children with CHD than for those with RHD. This correlation was also more significant than RVPEP/LVPEP, and RVET/LVET. The “a” dip correlated well with the diastolic PA pressure in CHD and RHD (r=.73). A multivariant analysis of the “a” dip and RVSTI ratios slightly improves the correlation coefficient and the prediction rate for PA diastolic pressures, PAR, and resistance ratios in CHD and CHD + RHD. Supported by the Swiss National Science Foundation grant 3563.0.75, and the Emil Barrel Fund     

Estimation of pulmonary artery pressure by contrast-enhanced Doppler signals and comparison with catheter-measured pressures.

Determination of pulmonary artery systolic pressure (PASP) is essential for the diagnosis, and the timing and type of management of patients with congenital heart disease (CHD). Usually cardiac catheterization, an expensive and invasive technique, is required for accurate measurement. A number of noninvasive methods for the assessment of PASP have been developed, one of which is estimation of PASP using contrast-enhanced tricuspid regurgitation Doppler signals (TRDS). In this study, right ventricular systolic pressures (RVSP) and PASP of 36 patients (19 girls, 17 boys; aged 5 months to 15 years) with CHD were estimated by TRDS before and after galactose solution (GS) and were compared with catheterization measurements. Significant TRDS (> 1 m sec.) were obtained in nine of 36 (25%), patients before GS and in 23 of 36 patients (64%) after GS. TRDS were increased significantly by contrast agent. Estimated RVSP and PASP were significantly different from the measured pressures before and after GS. There were significant correlations between the estimated RVSP and PASP and measured RVSP after GS. Estimated pressures were underestimated. We conclude that it is better to use the estimated PASP on patients with significant TRDS for the classification of PASP.     

Noninvasive assessment of surgical systemic to pulmonary artery shunts by range-gated pulsed Doppler echocardiography.

Suprasternal range-gated pulsed Doppler echocardiography was used to evaluate surgical shunt patency in children with cyanotic congenital heart disease and right ventricular outflow obstruction following systemic artery to pulmonary artery anastomoses. Normal patients had laminar Doppler auditory signals and time interval histogram flow patterns because right pulmonary artery turbulence was not present during systole or diastole. Patients with pulmonary valvar stenosis had turbulence during systole only. In all nine postoperative patients with surgical shunts, turbulent systolic and diastolic time interval histograms and abnormal auditory signals were present. A typical shunt murmur was not audible to auscultation in six of the postsurgical patients at the time of the study. Suprasternal range-gated pulsed Doppler echocardiography affords an accurate, safe and simple noninvasive bedside means for confirming shunt patency in patients who have undergone surgical systemic artery to pulmonary artery anastomoses.     

Prediction of peak pulmonary artery pressure by continuous-wave Doppler echocardiography in infants and children

Summary Continuous-wave Doppler echocardiography was used to estimate peak pulmonary artery (PA) pressure in 104 infants and children, aged 4 days to 16 years, with normal hearts (control group) and 43, aged 29 days to 13 years, with various kinds of heart disease (patient group). The Doppler transducer was directed toward the right ventricular outflow tract and angled until the maximal velocity signal was reached. Doppler velocity time intervals were measured as follows: acceleration time (AT), from the onset to the peak of the velocity curve; and ejection time (ET), from the onset to the termination of the velocity curve. In the control group, AT corrected through dividing by the RR interval of the electrocardiogram (ATc), and AT/ET by dividing by the square root of the RR interval (AT/ETc), were independent of body surface area. In the patient group, peak PA pressure had a significant inverse correlation with both ATc (r=-0.78) and AT/ETc (r=-0.87). Thus, AT/ETc derived from continuous-wave Doppler echocardiography is a good quantitative predictor of peak PA pressure in infants and children.     

Suprasternal Doppler ultrasound for assessment of stroke distance

An assessment of a non-invasive technique for measurement of stroke distance was made using a portable Doppler ultrasound machine. The aim was to determine the measurement error of repeated stroke distance measurements (Within-observer variability) and to assess measurement agreement between two operators (between-observer variability). The measurement error (within-observer variability) for both operators was similar at approximately 2 cm. However, the measurements of the two operators (between-observer variability) did not agree well. Using the mean (SD) of three readings by each operator, the mean difference between the operators was -0.21 cm (1.96) giving a 95% confidence interval for the differences of -4.0 to +3.6 cm. There were significant positive and negative correlations between stroke distance and a variety of variables (age, height, weight, heart rate), but the relations were weak. The results indicate that the Doppler ultrasound technique for measurement of stroke distance would best be used to study trend changes in an individual patient, or subject, by a single operator.     

Intraobserver and interobserver reliability in assessment of neonatal cranial ultrasounds.

Intraobserver and interobserver reliability in assessing neonatal cranial ultrasounds for periventricular-intraventricular hemorrhage (PVH-IVH) is not well studied; therefore, studies were designed to address this. For intraobserver reliability 180 cranial ultrasounds (360 hemispheres) were randomly selected from greater than 2000 ultrasounds and read twice by one radiologist in a blinded fashion. Ninety-eight percent were interpreted identically; of the 2% reinterpreted differently, all were initially abnormal but normal on the second reading. The least agreement occurred when interpreting ventricular size. Only four infants (1.1%) were placed in an unfavorable prognostic category (grades III and IV) on the first reading and a favorable prognostic category on the second interpretation (no bleed, grades I and II). To determine interobserver reliability, 20 sonograms were interpreted by eight independent observers representing five institutions. Using the multiple rater kappa kappa statistic, we determined interobserver agreement on overall impression (normal vs. abnormal), presence and extent of PVH-IVH (i.e. grade), presence of residual cyst, and ventricular dilatation. Greatest degree of agreement occurred when determining normal vs. abnormal, residual cyst, no bleed, and grades III and IV PVH-IVH. Poorest agreement occurred when reading grades I and II PVH-IVH and ventricular dilatation. After condensing interpretations of cranial ultrasounds into two prognostic categories, i.e. favorable (no bleed, grades I and II) and unfavorable (grades III and IV), there was excellent agreement among the observers.     

First trimester ultrasound screening for fetal aneuploidy and middle cerebral artery Doppler assessment for fetal alloimmunization

PURPOSE OF REVIEW: Traditional methods of fetal evaluation require invasive procedures (e.g. amniocentesis) with an inherent, albeit low, risk of complications and pregnancy loss. As medical knowledge and ultrasound technology have advanced, noninvasive modes of fetal evaluation have become increasingly used. Two disorders in which this has been most applied are fetal aneuploidy and alloimmunization to red blood cell antigens. RECENT FINDINGS: First-trimester screening protocols for fetal aneuploidy combine ultrasound measurement of the fetal nuchal translucency with the measurement of two maternal serum hormones, free beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A. This combination detects approximately 85% of women pregnant with fetuses with trisomy 21. An increase in the velocity of fetal middle cerebral artery blood flow occurs in the setting of moderate to severe fetal anemia and can be measured with Doppler ultrasound. Middle cerebral artery evaluation is equally sensitive in the prediction of anemia as amniocentesis for bilirubin breakdown products and has less associated risk. It has an additional benefit because it can also be applied to causes of anemia other than hemolysis. SUMMARY: Noninvasive methods of fetal assessment are becoming increasingly commonplace. There has been a dramatic decrease in the use of prenatal diagnostic services as screening strategies have become available. Doppler assessment of the velocity of blood flow through the fetal middle cerebral artery will allow for more judicious application of invasive procedures to pregnancies at significant risk for anemia.     

小儿扩张型心肌病肺动脉压的多普勒超声估测及其临床意义

目的估测扩张型心肌病肺动脉压并探讨其临床意义。方法用多普勒超声检查２６例扩张型心肌病患儿及２６名配对健康儿。肺动脉压用测三尖瓣最大返流速度及肺动脉血流加速时间（ＡＴ）两种方法估测。结果２６例患儿中２１例有三尖瓣返流，肺动脉收缩压（ＰＡＳＰ）３．２～１０．４ｋＰａ（６．０±１．９ｋＰａ）（２４～７５ｍｍＨｇ，１ｋＰａ＝７．５ｍｍＨｇ）。其中１８例（８６％）＞４ｋＰａ；对照组１４例有可测三尖瓣返流，ＰＡＳＰ均＜４ｋＰａ。患儿组ＡＴ缩短，ＡＴ与右室射血时间比值降低，也提示肺动脉压增高。ＰＡＳＰ与患儿左室短轴缩短分数、心功能低下持续时间及有无心内超声自发显影有关。随诊显示心功能好转者的ＰＡＳＰ较死亡或病情无改善者低，且后者肺动脉压继续增高。结论扩张型心肌病患儿多存在肺动脉高压，用多普勒超声估测的肺动脉压与患儿的病情及临床预后可能有一定的关系。     

Controlled hypercapnia and neonatal cerebral artery Doppler ultrasound waveforms

Eleven normal term infants undergoing respiratory assessment involving rebreathing to produce progressive hypercapnia were studied by Doppler ultrasound examination of an anterior cerebral artery during the procedure. A linear increase in end tidal carbon dioxide concentration from 4.5% to a maximum of 8.5% was documented during a period of 4-5 min rebreathing. A corresponding elevation of transcutaneous carbon dioxide tension was shown in the two infants monitored in this way. In all cases the Pourcelot index fell with rising end tidal carbon dioxide concentration. This fall in Pourcelot index was due to an increase in the diastolic frequency of the Doppler waveform. These results are consistent with the view that Pourcelot index correlates with cerebral vascular resistance distal to the site of recording.     

Doppler echocardiographic assessment of pulmonary blood flow in healthy newborns

The aim of this study was to determine interobserver variation in Doppler assessment of mean left pulmonary arterial flow velocity, and its normal values during the first 24 h of life. The interobserver variation was determined by a Bland and Altman analysis of the values of mean velocity measured in 21 newborns by 2 observers. Then, normal values of mean velocity were measured in 15 newborns at 5,10 and 15 min of life in the delivery room, and in 14 other newborns at 1, 2, 6, 12 and 24 h of life in the nursery unit. The interobserver variation was found to be acceptable. Mean velocity had a few variations within the first 24 h, but remained consistently above 20 cm s^-1. In conclusion, mean velocity values below 20 cm^-1 suggest low pulmonary blood flow.     

新生儿窒息肺动脉压力变化的无创性动态监测

目的　研究新生儿窒息后肺动脉压力的变化特点及临床意义 ,提供简便无创的检测方法。方法　应用彩色脉冲多谱勒超声于生后 2 4h内、3、7及 12～ 14d分别检测了 30例窒息新生儿及 2 5例正常新生儿左 /右心室射血前期、左 /右心室射血时间及其比值的变化 ,并依此推算肺动脉压力。结果　窒息与正常新生儿肺动脉压力在 2 4h内分别为肺动脉舒张压 (5 5 1± 17 3)mmHg对 (15 0± 3 0 )mmHg ,肺动脉阻力 (14 2± 3 9)mmHg/(L·min·m2 )对 (5 3± 1 3)mmHg/(L·min·m2 ) ,肺循环阻力 /体循环阻力比值 (0 84± 0 4 7)对 (0 2 7± 0 2 0 ) ,差异极显著 ,P <0 0 1。至生后 1周末 ,两组婴儿上述各指标间均无明显差异。结论　肺动脉高压是新生儿窒息的重要病理生理变化 ,在生后 1周内应重视对窒息新生儿肺动脉压力的检测。多谱勒超声心动图简便、无创 ,适于观察新生儿肺动脉压力的变化     

多普勒超声估测肺动脉平均压、肺血流量及全肺阻力的研究

目的 探索应用多普勒超声技术估测肺动脉平均压（PAMP）、肺血流量（QP）及全肺阻力（TPR）的新方法。方法 对28例左向右分流的先天性心脏病患儿,应用多普勒超声技术,根据改良肺动脉/主动脉血流时间间期比法（FPA/FAO）和容积血流测量技术估测PAMP及QP,按Poiseuille公式计算TPR,并与心导管实测值对比。结果 多普勒超声技术估测的PAMP、QP、TPR与心导管实测值高度相关（r=0.83、0.70、0.72 P<0.01）。结论 多普勒超声技术可以准确地估测PAMP、QP、TPR。     

CT assessment of tracheobronchial anomaly in left pulmonary artery sling

Background  

The left pulmonary artery sling (LPAS) is a rare vascular anomaly where the left pulmonary artery arises from the right pulmonary artery, passes over the right bronchus, and goes posteriorly between the trachea and esophagus. The LPAS is frequently associated with cardiac and non-cardiac defects including tracheobronchial abnormalities.     

Two-dimensional echocardiographic assessment of adequacy of pulmonary artery banding

The goal of banding the pulmonary artery (PA) in children with complex heart disease is to reduce PA pressure and blood flow, relieve symptoms of circulatory congestion, and insure low pulmonary vascular resistance for future repair. To assess the hypothesis that two-dimensional echocardiography (E) measurements could be used to predict noninvasively the tightness of the PA band by measuring its diameter, we examined 15 patients with PA band. Of the 12 patients who underwent cardiac catheterization, nine with no symptoms of circulatory congestion had distal systolic PA pressure less than 0.5 systemic, and three symptomatic patients had distal PA pressure of more than 0.5 systemic. None had left ventricular outflow tract obstruction or pulmonary vascular disease. The E measurements were the internal diameter of the PA band (d), and PA annulus (D) in diastole. The d/D ratios correlated significantly with the ratios of measured distal to proximal PA systolic pressure (r = 0.98, P less than 0.001). Of the three patients not catheterized, one had a d/D ratio of less than or equal to 0.4 and two greater than 0.4. The former one had an excellent clinical improvement after banding, while the latter two remained in circulatory congestion. Doppler echocardiographic evaluation in five patients did not improve upon the data from the d/D ratios.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pulsed Doppler ultrasound blood flow measurements in the superior mesenteric artery of the newborn

In 25 healthy newborns transcutaneous Doppler ultrasound measurements (Duplex-Scan) of flow velocities in the superior mesenteric artery were performed to define normal values and to investigate the response of intestinal blood flow to feeding. The diameter of the vessel was measured from real-time and M-mode imaging: mean value 3.2 mm. The analysis of the flow patterns before and after feeding revealed a significant change of the blood flow with increase of the peak velocity (Vp) (from 57±3.1 cm/sec to 97±11.5 cm/s) and the mean velocity (Vm) (from 22±1.6 cm/s to 41±4.1 cm/s). The pulsatility index decreased from 0.85 in the fasting baby to 0.73 45 min after feeding. The Vm was correlated with the post natal age and depended upon the quantity and quality of the meals. Neonates when fed only with tea/glucose 5% or small amounts of milk in the first 24h, showed a fasting Vm of about 17–18 cm/s. Neonates older than two days who were fed with increasing amounts of milk showed a mean pre feeding Vm of 30±3.8 cm/s.     

肺动脉压的无创性检测方法进展

正常肺动脉收缩压小于30mm Hg(1mm Hg=0.133kPa),平均压小于20mm Hg,舒张压小于15mm Hg;新生儿2周内的肺动脉收缩压可稍高,约为40mm Hg[1].当肺动脉压超过上述范围时,表示有肺动脉高压,通常继发于心肺疾病,也可由肺血管病变本身或其他疾病引起.肺动脉压的检测手段可分为有创性方法和无创性方法.有创性检测主要是右心导管检查,是诊断肺动脉高压的"金标准",可以直接测量肺动脉压并评价右心功能状态,其缺点是病情危重的新生儿无法承受.无创性检测手段众多,以超声心动图、胸部CT及MRI应用较多,这些无创性检查操作相对简单,风险较低,可重复进行,近几年得到迅速发展.