Maximum Peak Velocity Research Articles

Altered hepatic hemodynamics caused by temporary occlusion of the right hepatic vein: evaluation with Doppler US in 14 patients.

To evaluate with Doppler ultrasonography (US) the altered hepatic hemodynamics caused by temporary occlusion of the right hepatic vein. The study group consisted of 14 patients being considered for hepatic arterial infusion or transarterial embolization. In all patients, maximum peak velocity of the blood flow in the right portal vein was measured with Doppler US before and during the occlusion of the right hepatic vein. In 13 patients, color Doppler US was performed to evaluate Doppler signal in the portal venous branch in the occluded area before and during occlusion. Average peak velocity in the right hepatic artery in eight patients was measured by using a transducer-tipped guide wire before and during occlusion. Maximum peak velocity of the right portal vein significantly decreased with occlusion (P <.01). Hepatic venous occlusion changed the Doppler signal in the portal venous branch in the occluded area from hepatopetal to no signal in 10 patients; to weakened hepatopetal in two; and to hepatofugal in one. Average peak velocity of the right hepatic artery showed a decrease or plateau for 15-30 seconds after the start of occlusion and then a rapid increase to reach a plateau at around 75-90 seconds, with 1.5-2 times as much velocity as that before occlusion. Increase in hepatic arterial velocity is accompanied by a decrease in the portal velocity with temporary occlusion of the right hepatic vein; the expected increased drainage through the portal vein was almost undetectable.

3D Viscoelastic Wave Propagation in the Upper Borrego Valley, California, Constrained by Borehole and Surface Data

We have simulated 2-Hz-wave propagation in a three-dimensional model of the upper Borrego Valley, southern California, for a M 4.9 earthquake with epicenter 5 km north of the valley. A 4th-order staggered-grid finite-difference method was used to calculate viscoelastic ground motion in a basin model (9 km by 5 km by 0.4 km) consisting of heterogeneous sediments surrounded by bedrock. We simulated the earthquake as a double-couple point source and computed the ground motions in the valley separately for the parts of the source incident from below and from the North. The earthquake was recorded by a surface array as well as a deep downhole array (0–238 m depth) in the center of the valley, all equipped with digital three-component seismic instruments. The simulation reproduces the overall pattern of ground motions at basin and borehole sites and shows a good correlation of observed to synthetic waveforms. In particular, the 3D simulation reproduces the recorded peak motions, cumulative kinetic energies, and Fourier spectral amplitudes within a factor of 2 for most components at the individual sites. The correlation between data and simulation allows us to identify the secondary arrivals in the records as Love and Rayleigh waves generated at the edges of the valley and the troughs of the basin. The peak velocities for the waves incident into the valley from below are generally more than an order of magnitude larger than those for the waves incident from the North. The success of the prediction requires the inclusion of anelastic attenuation in the simulation with Q values for P and S waves in the alluvium of about 30. We also used a profile of the 3D model and the soil parameters at the deep borehole to examine the ability of 2.5D and 1D model approximations to predict the data. The maximum peak velocities and total cumulative kinetic energies are reproduced at the recording sites within a factor of 2 for both 2.5D and 1D model approximations, but are underpredicted by up to an order of magnitude at some depths for individual components. In particular, the 2.5D and 1D simulations tend to underpredict the duration.

Effect of distal stenosis of internal thoracic artery bypass grafts on longitudinal phasic blood flow velocity characteristics

Background Left internal thoracic artery (LITA) bypass conduits show gradual longitudinal transition in their phasic flow velocity patterns from the proximal to distal segments, but little is known about the influence of distal stenosis, particularly early after surgery, on that characteristic. The purpose of this study was to evaluate the influence of distal stenosis on these flow velocity patterns. Methods We examined 24 LITAs within 1 month (7 to 30 days) after surgery with a Doppler-tipped guide wire at the proximal, mid, and distal segments. Maximum peak velocities (MPV), time averaged peak velocities (APV), and velocity-time integrals (VTI) were measured. Results In LITAs without stenosis (n = 14, group A), the APV, MPV, and VTI values at the diastole were significantly greater than those for distal stenosis (minimal lumen diameter >75%, n = 10, group B). The values of the 3 indexes at the systole in each segment did not differ significantly between the 2 groups. Both groups showed gradual increases in the diastolic/systolic ratios of the 3 indexes from the proximal to distal portions, the ratios in group A being significantly larger than that in group B (APV, P < .001; MPV, P < .01; TVI, P < .01, respectively). For these indexes, sensitivity and specificity for predicting stenosis of LITA was higher in the proximal and mid portion than in the distal. Conclusions Anastomotic stenosis decreases the diastolic flow component but not the systolic one. By using diastolic/systolic ratios of the 3 indexes, it is possible to predict distal stenosis of LITA from the resting phasic flow velocity pattern. (Am Heart J 1999;138:468-76.)

Noninvasive Measurement of Left Coronary Blood Flow Reserve by Transthoracic Doppler Echocardiography: Comparison with Doppler Guidewire Ultrasonography.

The development of new ultrasound instrumentation has made epicardial coronary artery blood flow imaging easier with the use of transthoracic coronary Doppler echocardiography (TCDE). This study was performed to investigate the accuracy of coronary blood flow reserve (CFR) measurement by TCDE. In 15 patients with ischemic heart disease in the absence of valvular disease or atrial fibrillation, coronary flow at rest and flow with hyperemia induced by intravenous dipyridamole infusion were recorded by TCDE and Doppler guidewire ultrasonography. The CFR was determined as the ratio of the maximum hyperemic diastolic time-averaged peak velocity to the velocity at rest in the proximal or distal left anterior descending coronary artery. It was found that the CFR of the left anterior descending coronary artery measured by TCDE was comparable in accuracy with CFR measured by invasive methods (r = 0.87, P < 0.0001, n = 15).

Noninvasive assessment of the infarct-related coronary artery blood flow velocity using phase-contrast magnetic resonance imaging after coronary angioplasty

This study assesses infarct-related coronary artery blood flow velocity using phase-contrast magnetic resonance imaging (MRI) in patients with reperfused acute myocardial infarction (AMI) and compares these results with flow measurements obtained nonsimultaneously by intracoronary Doppler ultrasound. MRI examination was performed in 17 patients with AMI within 1 to 4 days (mean 2.5 days) after direct or rescue coronary angioplasty using a 0.014-in Doppler guidewire. MRI was performed on a 1.5-T clinical imager. The fast gradient echo segmented k-space phase-contrast pulse sequence was employed during breath-hold. The MRI and Doppler parameters of average peak velocity and maximum peak velocity were measured. Mean phase contrast MRI average peak velocity was 13.3 ± 10.7 cm/s, and mean phase-contrast MRI maximum peak velocity was 27 ± 16.6 cm/s. Mean Doppler average peak velocity was 17.1 ± 5.1 cm/s, and mean Doppler maximum peak velocity was 35.5 ± 10.1 cm/s. At the same anatomic levels, phase-contrast MRI average peak velocity correlated significantly to Doppler average peak velocity (r = 0.52; p <0.006) and Doppler maximum peak velocity (r = 0.42; p <0.03). Phase-contrast MRI velocity measurements were correlated with the same heterogeneity of Thrombolysis In Myocardial Infarction 3 flow velocity observed during Doppler examination. Thus, by comparing phase-contrast MRI with invasive intracoronary Doppler flow measurements, the measured MRI values showed significant correlation with Doppler data. Phase-contrast MRI has the potential to noninvasively quantify coronary flow velocity and to evaluate quality of reperfusion in patients with AMI after reperfused therapy.

Evaluation of the cushion setting on performance of a biodex II dynamometer

Objectives: To compare the effects of the soft cushion setting with those of the hard cushion setting of a Biodex II isokinetic dynamometer on peak velocity and peak torque with six loads at 23 preset speeds. Design: Mixed within- and between-groups, repeated-measures design. Setting: Research laboratory of a physical therapy education program. Interventions: Each load was strapped onto the right knee attachment of the dynamometer and was dropped through a 100° arc of motion five times at each preset speed using the soft and hard cushion settings. Main Outcome Measures: Peak velocity, peak torque, time to peak velocity, time to peak torque. Results: Peak velocity was significantly influenced by the cushion setting, the weight dropped, and the preset speed. Maximal peak velocity achieved was 400°/sec. Peak torque was influenced significantly by the cushion setting, the load, and the preset speed. Maximal peak torque measured was 34.99kg-m. Conclusion: The rotating shaft of Biodex II dynamometer moved at a slower speed through the entire arc of motion at the soft cushion setting and often failed to achieve a constant, preset speed. Peak torque measured using the soft cushion setting was more variable and therefore questionable.

Analysis of the velocity curve for height by the wavelet interpolation method in children classified by maturity rate.

The Wavelet Interpolation Method (WIM) developed by Meyer ([1992] Wavelets and Operators. Cambridge: Cambridge University Press) has been proposed as an analytical method for the accurate description of longitudinal growth velocity in height and identification of the age at maximum peak velocity (MPV) in the curve. The distance curve in height was determined by interpolating the longitudinal records of 98 boys and 88 girls, 6-17 years old, with the WIM. The distance curve was then differentiated to obtain a velocity curve. Age at MPV estimated from the velocity curve was utilized as a criterion of maturity rate (timing), and five maturity groups (early, little early, average, little late and late) were defined in both sexes. Four type models were derived from the occurrence of secondary peaks (mid-growth spurt and after-growth spurt): type model A, appearance of a mid-growth spurt and MPV; type model B, appearance of an after-growth spurt and MPV; type model C, appearance of a mid-growth spurt, an after-growth spurt and MPV; and type model D, appearance of MPV only. The individual growth data of boys and girls classified by maturity rate were sorted into the four type models. The frequency of occurrence of the four type models in groups classified by maturity rate was then analyzed, and the characteristics of height growth velocity was examined in boys and girls. Am. J. Hum. Biol. 11:13-30, 1999. Copyright 1999 Wiley-Liss, Inc.

Role of nitric oxide and cGMP in human septic serum-induced depression of cardiac myocyte contractility.

Previous studies have demonstrated the existence of a circulating myocardial depressant substance during human septic shock. We have recently identified this substance as a synergistic combination of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta). This study utilized an in vitro cardiac myocyte assay to evaluate the potential mechanistic role of nitric oxide (NO) and cGMP in depression of myocyte contractility induced by TNF-alpha, IL-1beta, TNF-alpha + IL-1beta (at low concentrations), and human septic shock serum (HSS). TNF-alpha, IL-1beta, TNF-alpha + IL-1beta, and each of 5 sera from patients with acute septic shock caused depression of both maximum extent and peak velocity of cardiac myocyte shortening and an increase in intracellular cGMP concentration during 30 min of exposure (minimum P < 0.01). NO synthetase (NOS) and guanylate cyclase inhibitors such as N-methyl-L-arginine (L-NMA) and methylene blue prevented these effects; an excess of L-arginine with L-NMA restored them (minimum P < 0.01). In contrast, D-arginine failed to reestablish cytokine-induced myocyte depression and cGMP accumulation prevented by L-NMA. Exposure of myocytes to TNF-alpha, IL-1beta, or TNF-alpha + IL-1beta produced a concentration-dependent increase in intracellular cGMP that paralleled the depression of cardiac myocyte contractility (minimum P < 0.001). In addition, TNF-alpha, IL-1beta, TNF-alpha + IL-1beta, or HSS application to cardiac myocytes resulted in increased NO gas generation, which was inhibited by L-NMA (minimum P < 0.01). Furthermore, unstimulated cardiac myocytes were shown to harbor constitutive but not inducible NOS activity. These data suggest that the sequential generation of NO by a constitutive NOS and cGMP by guanylate cyclase represents an important mechanism of cardiac myocyte depression by TNF-alpha, IL-1beta, TNF-alpha + IL-1beta, and the myocardial depressant substance(s) of septic shock.

An Investigation Regarding Sequence of Age at MPV in Physique Growth of Male Athletes

This paper is to discuss the sequence of age at MPV of height and weight in male athletes. In order to determine the age at MPV (Maximum Peak Velocity), the WIM (Wavelet Interpolation Method) was applied to longitudinal height and weight growth data of ages 6 to 17, and they were determined in fifteen male athletes (basketball: 6, track and field: 9). As control group, the ages at MPV of height and weight in 100 males who have standard stature (169-175cm) were determined by the WIM as well. The age at MPV of height in athletes group occurred earlier than in control group. It is suggested that the male athletes are of earlier matured type. On the sequence of age at MPV of height and weight, it is inferred that the case of same sequence appears more frequently than the case of regular sequence in the male athletes.

Transjugular intrahepatic portosystemic shunts: improved evaluation with echo-enhanced color Doppler sonography, power Doppler sonography, and spectral duplex sonography.

We assessed the feasibility of contrast-enhanced color Doppler, power Doppler, and spectral duplex sonography for visualization and quantification of flow through transjugular intrahepatic portosystemic shunts (TIPS) in patients in whom the baseline sonographic evaluation was unsatisfactory. Thirty-three patients underwent color Doppler, power Doppler, and spectral duplex sonography after TIPS insertion or before TIPS revision (mean time interval +/- SD, 1 +/- 1 day). All sonograms were obtained before and after patients received echo-enhancing contrast material. Sonography was evaluated with regard to presence or absence of flow in the mid portion, portal segment, and hepatic segment of the shunt. The maximal peak velocity was measured in the mid portion of the shunt. For identifying and quantifying stenoses, the percentage of luminal diameter reduction was calculated at the tightest part of the shunt. Shunt angiography and measurements of portosystemic pressure gradients were independently evaluated and compared with the sonographic findings. Flow visualization on unenhanced color Doppler sonography was significantly improved through the use of power Doppler sonography and contrast-enhanced color Doppler and power Doppler sonography (p < .01). Between contrast-enhanced power Doppler and contrast-enhanced color Doppler sonography, a significant difference was found in the portal and hepatic segments (p < .05). All shunt stenoses (n = 8) and occlusions (n = 3) were revealed by power Doppler sonography, whereas color Doppler sonography failed to reveal six of eight stenoses. Compared with unenhanced sonography, the quality of spectral duplex sonography was improved in eight patients after contrast enhancement (p < .05). Maximal peak velocity ranged from 54 to 252 cm/sec (mean +/- SD, 132.7 +/- 52.1 cm/sec) in normal shunts and from 24.5 to 70.0 cm/sec (mean +/- SD, 45.0 +/- 18.9 cm/sec) in stenosed shunts. No correlation was found between maximal peak velocity and portosystemic pressure gradients (r = .28). Unenhanced power Doppler and contrast-enhanced color and power Doppler sonography can be helpful in the assessment of TIPS status in patients who previously underwent unsatisfactory sonography. These techniques may allow anatomic evaluation and quantification of shunt stenosis in most patients. Contrast enhancement may also considerably improve the quality of spectral duplex sonography.

Which variable of stenosis severity best describes the significance of an isolated left anterior descending coronary artery lesion? Correlation between quantitative coronary angiography, intracoronary Doppler measurements and high dose dipyridamole echocardiography.

This study sought to investigate the angiographic or intracoronary Doppler variables of stenosis severity that best correlate with the results of dipyridamole echocardiography. Quantitative coronary angiography and intracoronary Doppler flow velocity assessments are the commonly used techniques for the objective identification of significant coronary artery stenosis. Thirty patients with an isolated lesion of the left anterior descending coronary artery (LAD) were studied by means of on-line quantitative coronary arteriography, intracoronary Doppler flow velocity measurements and dipyridamole echocardiography 6 months after percutaneous transluminal coronary angioplasty. The quantitative arteriographic analyses were performed on-line; post-stenotic Doppler flow velocities were measured at baseline and after adenosine infusion. Angiographic and Doppler measurements were compared with the corresponding dipyridamole echocardiographic data and analyzed by discriminant analysis. The dipyridamole echocardiographic response was positive in 11 patients (37%). The best cutoff values for predicting an abnormal echocardiographic response were 1) stenotic flow reserve of 2.8 (p = 0.0001); 2) 59% diameter stenosis (p = 0.0001); 3) minimal lumen diameter of 1.35 mm (p = 0.001); 4) coronary flow reserve of 2.0 (p = 0.0002); and 5) maximal peak velocity of 60 cm/s during hyperemia (p = 0.04). Multivariate analysis identified stenotic flow reserve as the only independent predictor of ischemia during dipyridamole echocardiography. Stenotic flow reserve is the variable that best describes the functional significance of an isolated LAD lesion, and a value of 2.8 is the best predictor of a positive dipyridamole echocardiographic response. Furthermore, angiographic variables of stenosis severity relate to echocardiographic test results better than intracoronary Doppler variables.

Do ultrasonic contrast agents artificially increase maximum Doppler shift? In vivo study of human common carotid arteries.

The aim of this study was to establish whether an increase of maximum Doppler shift occurs in the human common carotid artery after the administration of Levovist, an ultrasonographic echo enhancer. Twenty common carotid arteries of 10 patients were examined. Spectral Doppler waveform examinations were performed before and after administration of Levovist using an Acuson 128 XP 10 and a 7.0 MHz transducer probe. Time averaged mean velocity, peak velocity, maximum Doppler shift, and spectral Doppler indices (pulsatility index, resistive index, systolic-diastolic ratio) were assessed. No significant changes in any of the measured parameters, including maximum Doppler shifts, peak velocity (P = 0.35, Wilcoxon rank sum test), pulsatility indices (P = 0.70), resistive indices (P = 0.98), or other spectral indices, were found. We conclude that an increase in Doppler shift does not inevitably occur after the administration of a signal enhancer when examining the human common carotid artery.

Analysis of coronary flow reserve using Doppler guide wire in patients with chronic renal replacement therapy

To investigate the coronary blood flow dynamics in dialysis patients, we measured the coronary blood flow velocity and coronary flow reserve using Doppler guide wire. We studied 7 dialysis patients who had no significant coronary artery stenosis, but were suspected of ischemic heart disease due to their clinical symptoms and electrocardiographic findings. Mean age was 58 years old and mean duration of dialysis was 94 months. Eight non-uremic sujects who had no significant coronary artery stenosis served as controls.Using Doppler guide wire in the proximal left anterior descending artery, we analyzed the average peak velocity (APV), maximum peak velocity (MPV), and diastolic/systolic velocity ratio (DSVR) at baseline and a hyperemic stage. Coronary flow reserve was assessed by the ratio of flow velocity change induced by papaverine hydroclorie (10mg).The APV and MPV at the baseline of dialysis patients were significantly higher than those of the control patients. The coronary flow reserve of dialysis patients (2.3±0.7) was lower than that of the control patients (3.9±0.6).In conclusion, coronary flow reserve of dialysis patients was lower than that of the control patients due to high APV.

Stellenwert von Doppler-Blutflußgeschwindigkeitsmessungen bei peripheren perkutanen laserassistierten Angioplastien

The aim of the study was to establish the prognostic value and clinical implications of blood flow velocity measurements by Doppler guide wires during peripheral laser-assisted percutaneous transluminal angioplasty (PTLA). 39 patients presenting with symptomatic peripheral arterial obstructive disease underwent angiography and blood flow velocity assessment by Doppler guide wire (0.018") prior to and following PTLA. Both quantitative angiography (QCA) for measurement of luminal diameters and Doppler assessment of maximum peak velocities (MPV) were performed 2 cm proximal, over and 2 cm distal to stenoses. The results were compared with the following clinical endpoints: 1. Short-term clinical improvement by AHA-criteria during first follow-up examination and 2. criteria for patency suggested by Rutherford [12] within 1 year (1-22 months). Angiography demonstrated initial success of PTLA in all patients. Relative diameter stenosis decreased from 70 +/- 0.04% to 17 +/- 0.05%. Mean clinically category improved from 2.7 +/- 0.1 to 1.2 +/- 0.1 following intervention. Mean grade of clinical improvement was 2.8 +/- 0.1. 22/39 patients demonstrated event-free follow-up examinations. Doppler measurements of MPV post PTLA in the proximal reference segment correlated with clinical outcome. MPV > or = 90 cm/s was associated with good primary success, unlimited walking capacity and event-free follow-up. MPV > or = 70 cm/s predicted an improvement of short-term clinical outcome by 2 grades (predictive value 80%). MPV < 70 cm/s was associated with both minor primary clinical improvement (+/- 0, +1) and increased incidence of restenosis during follow-up. Following PTLA, MPV adds information to angiographic success. MPV > or = 90 cm/s in a proximal reference segment following PTLA predicts good clinical outcome, whereas MPV < 70 cm/s is associated with minor primary clinical success and increased rates of restenosis.

Tumor necrosis factor alpha and interleukin 1beta are responsible for in vitro myocardial cell depression induced by human septic shock serum

Previous studies have demonstrated the presence of myocardial depression in clinical and experimental septic shock. This depression is associated with the presence of a circulating myocardial depressant substance with physical characteristics consistent with cytokines. The present study utilized an in vitro myocardial cell assay to examine the role of various human recombinant cytokines, including tumor necrosis factor (TNF)alpha and interleukin (IL)1beta, in depression of cardiac myocyte contractile function induced by serum from humans with septic shock. The extent and velocity of electrically paced rat cardiac myocytes in tissue culture was quantified by a closed loop video tracking system. Individually, TNF-alpha and IL-1beta each caused significant concentration-dependent depression of maximum extent and peak velocity of myocyte shortening in vitro. In combination, TNF-alpha and IL-1beta induced depression of myocardial cell contractility at substantially lower concentrations consistent with a synergistic effect. Using immunoabsorption, removal of both TNF-alpha and IL-1beta (but not either alone) from the serum of five patients with acute septic shock and marked reversible myocardial depression resulted in elimination of serum myocardial depressant activity. IL-2, -4, -6, -8, -10, and interferon gamma failed to cause significant cardiac myocyte depression over a wide range of concentrations. These data demonstrate that TNF-alpha and IL-1beta cause depression of myocardial cell contraction in vitro and suggest that these two cytokines act synergistically to cause sepsis-associated myocardial depression in humans.

Transvaginal color Doppler determination of the ovarian and uterine blood flow characteristics in polycystic ovary disease

To determine blood flow characteristics of ovarian and uterine arteries in patients with endocrinologically and clinically confirmed polycystic ovary disease (PCOD) in comparison with blood flow parameters observed in patients with spontaneous ovulatory cycles. Controlled clinical study. Patients from Infertility Service in a tertiary care institution. Forty patients with confirmed PCOD and 50 control patients in various phases of spontaneous menstrual cycles. Using transvaginal color Doppler sonography to determine ovarian morphology, ovarian blood vessel visualization rates, and ovarian and uterine arteries blood flow parameters (resistance index, pulsatility index, and maximal peak velocity). These parameters were correlated with serum hormone levels. Polycystic ovaries showed typical vascular pattern: increased stromal vascularity, a positive correlation between increased blood velocities and serum LH levels, and a trend toward lower resistance index and pulsatility index values, whereas uterine arteries revealed significantly increased resistance index and pulsatility index values. The observed specific intraovarian and uterine vascular pattern in PCOD patients may provide additional data for conventional endocrinologic and ultrasonic diagnostic methods for PCOD.

男子体格の平均発育曲線から導き出される速度曲線の解析

This study is designed to determine Maximum Peak Velocity age (MPV) and examine the relationship between the MPV ages of height and other physique (body mass, chest girth, sitting height and leg length) in the growth velocity curve which differentiated the mean growth distance curve approximated by the Wavelet Interpolation Method (WIM) in physique. Furthermore analyzed the mid-growth spurt and the after-growth spurt. Ninety-eight longitudinal data of male students aged 6 to 17 years in physique (height, weight, chest girth, sitting height, leg length) were obtained retrospectively from health examination records in 1983. Specifically, the growth curve constracted theoretically based upon the Multiresolution phenomenon (Self-similar phenomenon in the terminology of Fractal) was abstracted as human growth phenomena, and the abstracted growth curve was approximately described as the true growth curve by the WIM. The MPV ages of physique by identified by judging from the growth velocity curve simulated by the WIM, and the sequence in the MPV ages of physique was leg length (11.78), height (12.21), sitting height (12.57), weight (12.60), and chest girth (12.81) in early order of MPV age. Significant (P &lt 0.01) correlations were obtained between the MPV ages of height and other physical measurements. It was shown that differences between the MPV ages of height and physique except height had fixed tendency respectively. The mid-growth spurt was confirmed in the growth velocity curve of weight and chest girth, and the after-growth spurt was confirmed in those of height and leg length. Consequently, it was considered that the after-growth spurt of height was determined by that of leg length.

Assessment of the Hemodynamic Result of PTA with a Doppler Guide Wire: Initial Experience

To determine the usefulness of a Doppler guide wire for assessing the hemodynamic results of balloon dilation of atherosclerotic arterial obstruction. A 0.018-inch 12-MHz Doppler guide wire was used to measure the maximum peak velocity and the time-averaged peak velocity (APV) proximal to, inside, and distal to lesions in 10 consecutively seen patients (six men, four women; mean age, 68 years +/- 11 [standard deviation]). Measurements were made before and after percutaneous transluminal angioplasty (PTA). The proximal-to-intrastenotic APV ratio was the best predictor of the grade of residual stenosis and correlated well with angiographic measurements (r = .8). Balloon dilation resulted in a significant increase in mean APV distal to the obstruction (12.5 cm/sec before versus 27.6 cm/sec after PTA; P < .05). The mean proximal-to-distal APV ratio also decreased significantly (3.7 before versus 1.0 after PTA; P < .005). The Doppler guide wire can be used for direct intravascular evaluation of the result of balloon dilation in atherosclerotic obstructions.

Coronary Arterial Flow-Velocity Dynamics in Children With Angiographically Normal Coronary Arteries

There have been few reports about coronary hemodynamics in children during the process of growth. In the present study, to assess the characteristics of coronary flow dynamics in children, we examined the phasic coronary flow-velocity (CFV) patterns at rest and during peak hyperemic responses in children with angiographically normal coronary arteries. Spectral Doppler phasic coronary flow velocity was recorded with a 0.018-in intracoronary Doppler guidewire at rest and during peak responses after intracoronary bolus injection of ATP in 30 patients with Kawasaki's disease (age, 8.2 +/- 5.1 years; 24 boys and 6 girls) without angiographic coronary lesions. Average peak velocity (APV), maximum peak velocity (MPV), and diastolic-to-systolic velocity ratio (DSVR) were evaluated in the left anterior descending coronary artery (LAD), left circumflex artery (LCx), and right coronary artery (RCA). Coronary vasodilator reserve (coronary flow reserve [CFR]) was calculated as the ratio of ATP-induced hyperemic to baseline APV. Flow-velocity parameters in RCA were significantly lower than those in the LAD and LCx in both proximal and distal portions. Although the distal LCx had significantly lower values of APV and MPV than did the proximal LCx, there was no significant difference between the proximal and distal portions of the LAD and RCA for APV and MPV. All three coronary vessels showed a diastolic dominant flow pattern in each segment. This coronary flow pattern was less marked in the RCA than in the LCA. All three coronary vessels showed a significant increase in APV and a significantly decrease in DSVR after ATP administration. CFR was significantly lower in the LCx than in the LAD or RCA (P < .01: 1.93 +/- 0.34 in LCx versus 2.32 +/- 0.42 in LAD and 2.37 +/- 0.44 in RCA). From the view of aging, it was revealed that APV values in three vessels were higher in the younger group than in the older group. CFR values in the LAD and LCx were significantly lower in the younger group than in the older group (P < .001 in LAD: 2.01 +/- 0.28 in the younger versus 2.53 +/- 0.37 in the older; P < .01 in LCx: 1.61 +/- 0.15 in the younger versus 2.06 +/- 0.31 in the older). In addition, intracoronary injection of ATP did not increase the absolute angiographic coronary luminal diameter. With the use of an intracoronary Doppler guidewire, we demonstrated that there are some characteristic findings in CFV dynamics in childhood. These physiological characteristics in CFV dynamics that occur with aging and occur in each vessel must be taken into consideration in the study of the coronary circulation in children.

Transesophageal color Doppler evaluation of obstructive lesions using the new “Quasar” technology

Due to the unavoidable problem of aliasing, color flow signals from high blood flow velocities cannot be measured directly by conventional color Doppler. A new technology termed Quantitative Un-Aliased Speed Algorithm Recognition (Quasar) has been developed to overcome this limitation. Employing this technology, we used transesophageal color Doppler echocardiography to investigate whether the velocities detected by the Quasar would correlate with those obtained by continuous-wave Doppler both in vitro and in vivo. In the in vitro study, a 5.0 MHz transesophageal transducer of a Kontron Sigma 44 color Doppler flow system was used. Fourteen different peak velocities calculated and recorded by color Doppler-guided continuous-wave Doppler were randomly selected. In the clinical study, intraoperative transesophageal echocardiography was performed using the same transducer 18 adults (13 aortic valve stenosis, 2 aortic and 2 mitral stenosis, 2 hypertrophic obstructive cardiomyopathy and 1 mitral valve stenosis). Following each continuous-wave Doppler measurement, the Quasar was activated, and a small Quasar marker was placed in the brightest area of the color flow jet to obtain the maximum mean velocity readout. The maximum mean velocities measured by Quasar closely correlated with maximum peak velocities obtained by color flow guided continuous-wave Doppler in both in vitro (0.53 to 1.65 m/s, r = 0.99) and in vivo studies (1.50 to 6.01 m/s, r = 0.97). We conclude that the new Quasar technology can accurately measure high blood flow velocities during transesophageal color Doppler echocardiography. This technique has the potential of obviating the need for continuous-wave Doppler.