PW Doppler Research Articles

Normal values of blood flow velocity in the terminal vein of preterm infants

Evaluation of blood flow velocity in terminal veins of both cerebral hemispheres by Doppler-sonographic measurement. The examinations were done in clinically stable, non-ventilated preterm infants between gestational weeks 29 and 36. Terminal veins were localised by colour duplex sonography, then the maximal blood flow velocity was measured by PW Doppler. Every measurement was repeated for accuracy. From the averaged data, percentiles were calculated for both cerebral hemispheres. A linear correlation between gestational age and maximal blood flow velocity in the terminal vein was seen. The maximal blood flow velocity increased from 3.2 cm/sec at 29 weeks to 4.6 cm/sec at 36 weeks. No difference could be seen between both cerebral hemispheres. Percentiles could be calculated for the blood flow velocity in the terminal vein of both cerebral hemispheres. Maximal blood flow velocity increases from 29 to 36 weeks of gestational age. Serial examination during the first days of life are a feasible tool for detecting preterm infants at risk for intracerebral haemorrhage or infarction.

ECHOCARDIOGRAPHIC QUANTIFICATION OF RIGHT VENTRICULAR FUNCTION IN THE LATE FOLLOW‐UP OF SENNING PROCEDURE

Background: Deteriorating ventricular function is a major concern after Senning operation. Echocardiographic assessment of right ventricular (RV) function is limited because of the complex geometry of this ventricle. A myocardial performance index (MPI) that is a Doppler‐derived nongeometric measurement has been reported in adults and children. Because this index is independent of geometry it may be particularly useful in the evaluation of the RV function. The aims of this study were: (1)‐ to prospectively determine normal values for RVMPI in patients in the late follow‐up of Senning procedure; (2)‐ to correlate the ejection fraction (EF) and dP/dt measured by echocardiography (ECHO) with the EF measured by magnetic resonance imaging (MRI). Methods: From August 1999 to March 2003, 44 patients submitted to Senning procedure were prospectively studied by echo and MRI. Mean age was 16.7 years (12–26 years). Mean postoperative period was 15.3 years (10–23.5 years). Forty‐one patients were in NYHA Class I, and 3. The RVMPI was calculated using PW Doppler from tricuspid inflow and aortic outflow, the EF by the modified Simpson's rule, and the dP/dt by CW Doppler tricuspid regurgitation signal. All patients underwent MRI and Echo within one month. The Echo results were compared to RV EF calculated by MRI. Results: RVMPI ranged from 0.16 to 1.42 (mean = 0.50). The EF calculated by echo ranged from 6% to 63% (mean = 39%). Th dP/dt was calculated in 29 raging from 457 to 3213 mmHg/s (mean = 1398 mmHg/s). By MRI the EF ranged from 16% to 85% (mean = 60%). A cut‐off value of 0.47 for the RVMPI was determined (ROC curve), with a sensitivity of 75% and a specificity of 62.5%. There was no correlation between the EF and dP/dt calculated by ECHO and the EF calculated by MRI (R2= 0.29 and 0.04 respectively). The NYHA functional classes of the patients did not correlate with RVMPI or MRI values (Kappa). Conclusion: (1)‐Patients with normal RV function had RVMPI values <0.47, and this index could be useful in the evaluation of Senning procedure; (2)‐ no correlation between the EF and dP/dt calculated by ECHO and the EF calculated by MRI was found.

Angiogenesis: CDI, PW Doppler, and B-flow in characterizing superficial masses

Objective: The aim of this study was to characterize superficial lymph nodes by their vessel morphology and architecture by using B-flow, CDI, and PW Doppler.Methods: Tumor vascularity of superficial lymph nodes (LN) in 27 patients with non-Hodgkin lymphoma (NHL), carcinomas (n=11) and inflamed LN (n=9) were examined using a digital gray scale flow detection subtraction method (B-flow, US device: LOGIQ 7, 10 L probe, GE, USA). CDI, PW Doppler, and cytology/histology were performed in all cases.Results: Vessels down to 0.2 mm could be imaged with B-flow without blooming artifacts. Tumor vessel characteristics were: vessel type, variety in regional vessel density, course of the arteries, diameter, sudden change of lumen and doubled or dual channel arteries. In 9/11 LN mets from carcinomas none or only few central arteries were detected. 7/11 showed tortuous course of arteries. The RI number varied largely. 2/11 with a rapid lymphatic metastatic spread had also venous flow in patients different to inflamed LN. In most malignant LN, venous flow was predominately detected around the LN (18/27). In contrast to low malignant NHL, high malignant NHL showed only arteries in the center and veins in the periphery. All NHL with low-grade malignancy showed parallel course of veins and arteries. In comparison to NHL, inflamed LN have similar vessel architecture and RI numbers, and thus cannot be differentiated from low NHL.Conclusions: B-flow can demonstrate typical morphology of tumor vessels in LN, which can be explained by tumor angiogenesis: Course of the arteries, their architecture, and lack of central veins are characteristic signs for malignancy. Dominating arteries and an intratumoral change of vessel density may reflect different intratumoral pressures and thus explain the wide range of RI measurements. Only in LN with suspected high lymphangiogentic activity, intratumoral pressure was low and thus showed also venous flow. Objective: The aim of this study was to characterize superficial lymph nodes by their vessel morphology and architecture by using B-flow, CDI, and PW Doppler. Methods: Tumor vascularity of superficial lymph nodes (LN) in 27 patients with non-Hodgkin lymphoma (NHL), carcinomas (n=11) and inflamed LN (n=9) were examined using a digital gray scale flow detection subtraction method (B-flow, US device: LOGIQ 7, 10 L probe, GE, USA). CDI, PW Doppler, and cytology/histology were performed in all cases. Results: Vessels down to 0.2 mm could be imaged with B-flow without blooming artifacts. Tumor vessel characteristics were: vessel type, variety in regional vessel density, course of the arteries, diameter, sudden change of lumen and doubled or dual channel arteries. In 9/11 LN mets from carcinomas none or only few central arteries were detected. 7/11 showed tortuous course of arteries. The RI number varied largely. 2/11 with a rapid lymphatic metastatic spread had also venous flow in patients different to inflamed LN. In most malignant LN, venous flow was predominately detected around the LN (18/27). In contrast to low malignant NHL, high malignant NHL showed only arteries in the center and veins in the periphery. All NHL with low-grade malignancy showed parallel course of veins and arteries. In comparison to NHL, inflamed LN have similar vessel architecture and RI numbers, and thus cannot be differentiated from low NHL. Conclusions: B-flow can demonstrate typical morphology of tumor vessels in LN, which can be explained by tumor angiogenesis: Course of the arteries, their architecture, and lack of central veins are characteristic signs for malignancy. Dominating arteries and an intratumoral change of vessel density may reflect different intratumoral pressures and thus explain the wide range of RI measurements. Only in LN with suspected high lymphangiogentic activity, intratumoral pressure was low and thus showed also venous flow.

B-flow technique provides morphological information about ICA plaque character in addition to B-mode and CDI

Objective: After a routine carotid examination (B-mode, CDI, and PW Doppler), a B-flow examination was performed to see if it provided additional information on the plaque morphology. Methods: We used the US device, LOGIQ 7, 10L Probe (GEMS, Europe, Solingen). Blood flow of 65 patients with ICA plaques and an ICA stenosis exceeding 50% were examined in CDI and B-flow technique. Plaque contour, ulceration, elasticity, and shape of the residual lumen were evaluated. Results: Due to calcifications, the plaque contour of 9/65 ICA stenoses could not be evaluated completely. B-flow showed that 28/56 had a smooth plaque surface, and 20/56 had an undulating surface. CDI could not demonstrate minor changes of the plaque surface. 9/56 had ulceration of a soft plaque, the smallest one measured 2 mm at the basis. 1/9 had a thombosed ulceration that could not be seen in CDI or B-mode. 2/9 ulcerations were seen behind a calcified plaque. Only the three largest ulcerations could be seen with CDI. To calculate the degree of stenosis correctly, the residual lumen area at the site of stenosis was imaged 90°. In 89%, the lumen of the stenotic segment was eccentric. 68% had an oval or sickle-like shape of the residual lumen. B-flow helped to demonstrate the plaque elasticity by evaluating the change of the lumen area but not of the vessel area over a cardiac cycle. 4% of the plaques were compressed during systole. Due to blooming, CDI could not image a plaque compression during systole. Conclusions: B-Flow technique is superior to CDI in demonstrating plaque contour, ulcerations, and elasticity. At 90°, the shape of the residual lumen can be displayed, which is mandatory for the correct calculation of the stenotic ICA area.

Noninvasive determination of coronary flow reserve with signal enhanced high resolution transthoracic Doppler color echocardiography

The feasibility of non-invasive assessment of coronary flow reserve (CFR) in the left anterior descending artery (LAD) using echo-enhanced high-resolution transthoracic color Doppler echocardiography (TTCD) was investigated. The results were compared with the degree of coronary diameter-stenosis obtained during cardiac catheterization. CFR has proven to be useful in the selection of patients undergoing invasive treatment of coronary artery disease and in estimating their prognosis. However, CFR could only be determined in everyday practice invasively during catheterization procedures. Recent development of high-resolution TTCD allows transthoracic visualization of distal LAD and supra-apical intramyocardial perforator branches, and non-invasive measurement of CFR. CFR was determined by measuring the ratio of pulsed-wave Doppler time velocity integral during adenosine-induced hyperemia (140 micrograms/kg/min i.v.) to baseline value. If Doppler signal of LAD flow was insufficiently at basal condition, an echo enhancer (Levovist) was used. 45 patients were examined by TTCD (7 MHz B-mode, 5 MHz color Doppler, 3.5 MHz PW Doppler) after coronary angiography had been performed. Group I consisted of 15 patients without heart disease, Group II of 15 patients with 40 to 70% isolated LAD diameter stenosis, and Group III of 15 patients with > 70% LAD diameter stenosis. Peripheral LAD coronary flow at baseline condition was assessed in 40 patients (88%) using TTCD. CFR could be quantified in 36/45 patients (80%), in 18 patients without echo enhancer, and in 18 patients with echo-enhancing agent. In 9/45 patients CFR could not be assessed. CFR in Group I was 3.13 +/- 0.57, in Group II 2.23 +/- 0.20 (vs Group I p < 0.01) and in Group III 1.64 +/- 0.30 (vs Group II p < 0.02). CFR of LAD can be determined in 80% of patients by the synergistic use of high-resolution TTCD combined with intravenous given ultrasound echo-enhancing agent.

In situ measurements of Doppler power vs. flow turbulence intensity in red cell suspensions

Whereas previous studies have shown that ultrasonic backscatter and Doppler power from blood are affected by flow turbulence, turbulence level has only been inferred from the flow Reynolds number and not directly measured. In this study, both ultrasonic Doppler power and flow turbulence intensity were measured in situ to quantify the relationship between Doppler power and flow turbulence. Three grid meshes of different geometries were used in a steady-flow mock loop to generate controlled levels of flow turbulence in porcine red blood cell saline suspensions. Doppler power was measured by a 10-MHz PW Doppler flowmeter, and the turbulence intensity by using constant-temperature hot film anemometry. We showed that Doppler power is affected by turbulence and hematocrit in a complex way. At a fixed hematocrit, Doppler power increases nonlinearly with turbulence intensity and, at fixed turbulence intensity, Doppler power peaks at an optimal hematocrit level that increases with turbulence level. The shape factor, introduced by Lucas and Twersky (1987) to take into account effects of shape and orientation of the scatterers in a dense distribution of small and tenuous scatterers, was estimated by fitting the experimental data to the theoretical model. The results indicate that shape factor decreases with increasing turbulence intensity.

Design parameters of pulsed wave ultrasonic Doppler blood flowmeter.

Pulse wave Doppler techniques promise the ability to make more effective measurements of dynamic cardiovascular functions. Quantitative measurement of blood flow can be achieved by using the pulse wave Doppler system. This paper discusses the design parameters of the pulse wave Doppler blood flowmeter (PW Doppler) with respect to the physiological system.

Analytical and experimental comparisons between the frequency-modulated–frequency-shift measurement and the pulsed-wave–time-shift measurement Doppler systems

In previous publications, a new echo-ranging Doppler system based on transmission of repetitive coherent frequency-modulated (FM) sinusoids in two different implementations was presented. One of these implementations, the frequency-modulated–frequency-shift measurement (FM–fsm) Doppler system is, in this paper, compared with its pulsed-wave counterpart, the pulsed-wave–time-shift measurement (PW–tsm) Doppler system. When using transmitted PW and FM signals with a Gaussian envelope, the parallelism between the two systems can be stated explicitly and comparison can be made between the main performance indices for the two Doppler systems. The performance of the FM and PW Doppler systems is evaluated by means of numerical simulation and measurements of actual flow profiles. The results indicate that the two Doppler systems have very similar levels of performance.

Angle dependence and transit time effect in Doppler flow measurement

Objective: In clinical practice, obvious differences exist between the Doppler theory which does not allow a frequency shift at right angles of insonation, and the fact that a frequency is generated. Possible technical and physical causes were evaluated in our study. Methods: A laminar, non-pulsatile flow model was insonated between 35° and 155° with pulsed wave (pw) Doppler sonography incorporated in a duplex scanner. Results: For all angles tested the maximum frequencies were higher than predicted by the Doppler formula. The frequency shift observed at perpendicular insonation cannot be explained by the Doppler theory. Conclusions: The results obtained can be explained by intrinsic spectral broadening (ISB) caused by the transit time effect or equivalently by the geometry of the ultrasonic beam. These effects have to be considered when the maximum frequency is employed to quantify flow volume or when spectral broadening is used as an indicator of disturbed flow.

Angle dependence and transit time effect in Doppler flow measurement

Objective: In clinical practice, obvious differences exist between the Doppler theory which does not allow a frequency shift at right angles of insonation, and the fact that a frequency is generated. Possible technical and physical causes were evaluated in our study. Methods: A laminar, non-pulsatile flow model was insonated between 35° and 155° with pulsed wave (pw) Doppler sonography incorporated in a duplex scanner. Results: For all angles tested the maximum frequencies were higher than predicted by the Doppler formula. The frequency shift observed at perpendicular insonation cannot be explained by the Doppler theory. Conclusions: The results obtained can be explained by intrinsic spectral broadening (ISB) caused by the transit time effect or equivalently by the geometry of the ultrasonic beam. These effects have to be considered when the maximum frequency is employed to quantify flow volume or when spectral broadening is used as an indicator of disturbed flow.

1024-81 Aortic Dilation in Young Males with Isolated Normally Functioning Bicuspid Aortic Valve

Bicuspid aortic valve (BAV) is a common congenital disorder frequently coexisting with abnormalities of the aortic arch including aortic coarctation, dissecting aneurysm and aortic root dilation: it has been suggested that these associations result from a common developmental defect. Moreover, aortic root dimensions are influenced by age and body size; thus, in order to test the hypothesis of a common congenital disorder underlying BAV and aortic dilation, we prospectively studied young males with isolated, normally functioning bicuspid aortic valve during the medical examinations for the military service, in comparison with a age-matched group with no cardiovascular abnormalities. Sixty-three patients (aged 17.8 ± 0.6 year, range 17-19) whose echocardiograms showed a normally functioning BAV were studied at the Military Hospital in Verona by 2D echocardiography with PW, CW and Color Doppler. Seventy subjects, comparable for age (17.82 ± 0.7, range 17-19) and body surface area (1.79 ± 0.09 vs 1.82 ± 0.08, respectively) without clinical and echocardiographic evidence of cardiac abnormalities, were used as control group. Aortic root dimensions were measured by 2D-echocardiography at four levels: 1) anulus, 2) sinuses on Valsalva, 3) supraaortic ridge and 4) proximal ascending aorta. Results (mean ± SD): Level BAV Normals p Anulus 2.36 ± 0.31 2.27 ± 0.29 NS Sinuses of Valsalva 3.16 ± 0.38 2.90 ± 0.32 &lt;0.01 Supraaortic ridge 2.64 ± 0.46 2.50 ± 0.28 0.03 Proximal Ascending Aorta 3.12 ± 0.48 2.71 ± 0.29 &lt;0.01 Aortic root dimensions are significantly greater in young men with normally functioning BAV than in control subjects comparable for gender, age and body size. Noticeably, the aortic root dimensions in patients with BAV are still within the range of normality. These data confirm the hypothesis that BAV and aortic dilation are expression of a common developmental defect.

Ultrasound FM doppler systems for flow profiling with comparison to PW Doppler systems

Ultrasound FM doppler systems for flow profiling with comparison to PW Doppler systems

Effects of Nebivolol on Left Ventricular Function in Patients with Essential Hypertension

30 patients (20 male and 10 female, mean age 53 years) with mild to moderate essential hypertension took part in a double-blind randomised study to evaluate the effects of nebivolol (5 mg/day) vs atenolol (100 mg/day). Systolic and diastolic blood pressure (BP) were recorded by 24-hour ambulatory BP monitoring after 4 weeks’ placebo and 8 weeks’ active treatment. Systolic and diastolic left ventricular function were measured using a 2-dimensional ECG and PW Doppler transmitral blood flow velocity recordings. The 2 drugs produced similar reductions in BP, whereas only atenolol significantly decreased heart rate. Cardiac index was unchanged with both drugs. An improvement was observed in different indices of diastolic left ventricular function with both treatments. However, only nebivolol enhanced the peak filling rate normalised to mitral stroke volume, from 5.4 to 6.5 sec−1 (p < 0.05).

Long-term follow-up of carotid disease: clinical and ultrasound aspects.

Various non-invasive techniques were used to study clinical and ultrasound aspects of extracranial arterial disease. cw Doppler was used prospectively to study the natural history of asymptomatic extracranial arterial disease (greater than 50% carotid stenosis, subclavian steal phenomena) in 401 patients. Whereas the cumulative death rate was high (44%) at 8 years, the stroke rate was low (6%). Progression of the vascular processes during follow-up correlated with later cerebrovascular events. Transcranial PW Doppler was used to study the intracranial collaterlisation in 151 asymptomatic patients with significant extracranial lesions. The majority of patients showed excellent collateralisation. The natural history of non-stenotic plaques (less than 30% carotid stenosis) was studied by means of high-resolution (10 MHz) duplex system analysis. Whilst most plaques remained constant during the subsequent follow-up period progression was seen in 24% and regression in 10%.

Different determinants of left ventricular filling in normotensive subjects and essential hypertensive patients.

The aim of the study was to evaluate the relationships between left ventricular (LV) filling and age, heart rate (HR), blood pressure (BP), and LV mass in three groups of subjects with different casual blood pressure. Twenty normotensive subjects (NT: age 39.2 +/- 7.2; BP 121.6 +/- 11.3/77.7 +/- 7.5 mm Hg), 16 borderline hypertensives (BH: age 38.6 +/- 9.2; BP 138.2 +/- 11.6/91.7 +/- 9.4 mm Hg), and 20 essential hypertensives (EH: age 44.5 +/- 8.3; BP 165.7 +/- 14.8/107.6 +/- 11.4 mm Hg) underwent 2D Echo evaluation and PW Doppler measurements of transmitral blood flow velocity. In NT, the Doppler indexes of LV filling showed significant correlations only with age and heart rate (age v E peak: r = .68 P less than .001; v A peak: r = .45, P less than .05; v A/E: r = .78, P less than .001. Heart rate v A peak: r = .78, P less than .001, v A/E: r = .74, P less than .001, respectively). Similar but weaker relationships were observed in BH. On the contrary, EH showed no significant correlations with age or heart rate, but with both systolic blood pressure (SBP), diastolic blood pressure (DBP), and LV mass (SBP v A peak: r = .49, P less than .05; v A/E: r = .68, P less than .001; DBP v E peak: r = 44, P less than .05; v A/E: r = .58, P less than .01. Left ventricular mass v E peak: r = .45, P less than .05; v A/E: r = .51, P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)