Left ventricular function in children with the Marfan syndrome

Aortic dilatation and heart valve lesions are common in the Marfan syndrome but whether primary alterations occur in left ventricular (LV) function has not been studied hitherto. LV size, mass and systolic as well as diastolic function were studied by M-mode and Doppler echocardiography and cine magnetic resonance imaging in 22 Marfan children aged 3.0-15.4 years and in 22 age-matched healthy children. No child had significant valve disease. Heart rate and systolic blood pressure were comparable in the groups but diastolic blood pressure was higher in the controls (67 +/- 7 mmHg vs 62 +/- 8 mmHg, P = 0.030). No statistically significant differences were found in LV size, mass or systolic function. The Marfan children had slower LV peak diameter lengthening rates (106 +/- 27 mm.s-1 vs 132 +/- 29 mm.s-1, P = 0.004), prolonged relaxation times (155 +/- 22 ms vs 140 +/- 19 ms, P = 0.023), slower deceleration of the early transmitral velocity (580 +/- 144 cm.s-1 vs 720 +/- 160 cm.s-2, P = 0.006), and smaller early-to-late peak velocity ratios (1.99 +/- 0.40 vs 2.29 +/- 0.46, P = 0.031). These data indicate that LV early diastolic function (relaxation) is impaired in the Marfan syndrome. Weakened elastic recoil due to the underlying connective tissue abnormality may best explain this novel observation.     

New nortriterpenoid isolated from anti-rheumatoid arthritic plant, Tripterygium wilfordii, modulates tumor growth and neovascularization

Noninvasive measurement of blood flow velocity through the cardiac valves has important clinical applications. A wide variety of MR methods are available for flow measurement. The aim of this study was to investigate the ability of cine MR Fourier velocimetry to measure flow through healthy cardiac valves and to compare MR and Doppler peak velocity measurements. Ten healthy volunteers (age mean +/- SD, 24 +/- 4 years) without history of valvular disease were studied. Four of the subjects were females. In each subject, aortic, pulmonary, mitral, and tricuspid valves were evaluated with MR and Doppler imaging. A whole-body mobile MR machine was used, operating at .5-T with actively shielded magnetic field gradient coils on all three axes capable of 20 mT/m at a slew rate of 60 mT/ m/msec. The heart rate during MR and Doppler studies was not significantly different. The mean difference between the two studies was 2 beats/min, with a 95% confidence interval of -22 beats/min, +25 beats/ min. Peak systolic flow velocity in the aortic and pulmonary valves and peak diastolic flow velocity in the mitral and tricuspid valves measured with MRI and Doppler echocardiography correlated well. The mean difference between the two measurements (MR-Doppler) was 63 mm/sec, with a 95% confidence interval of -180 mm/sec, +310 mm/sec. The agreement between two observers interpreting the same MR velocity maps was close. The mean difference between their two measurements was 23 mm/sec, with a 95% confidence interval of -20 mm/sec, +60 mm/sec. There was no significant difference between MR and Doppler imaging or between the two MR observers. MR Fourier velocimetry has the necessary ease, reliability, and speed to measure blood flow through the cardiac valves, although measurement of late diastolic flow in the atrioventricular valves is limited. Measurement of peak blood velocity through the cardiac valves by this method showed satisfactory agreement with Doppler, but its clinical application for assessing diseased cardiac valves must be established.     

Study of the coronary flow with high resolution transthoracic echocardiography and nondirectional Doppler

Two-dimensional echocardiography allows to evaluate the effect of myocardial ischemia on left ventricular wall motion, but a direct measure of coronary flow by this method is still lacking. The aim of the present study was to evaluate the efficacy of a new, high-resolution echocardiographic equipment designed to image the epicardial and intramural coronary vessels by non directional Doppler. We studied 33 consecutive patients by transthoracic echocardiography in apical projections, to detect one or more segments of the left anterior descending coronary artery by non directional Doppler. Once the coronary artery has been imaged, pulsed Doppler was used to measure coronary blood flow velocity at rest. Peak and mean flow velocities were measured on the diastolic phase of the Doppler spectrum. In 25/33 patients (75.7%) the middle-distal tract of the left anterior descending coronary artery was imaged by non directional Doppler. In 15/33 patients (45.5%) the periapical tract of the left anterior descending coronary artery was imaged along with its perforating branches. In 2 out of 4 patients operated of coronary artery bypass grafting, the anastomosis between the left internal mammary artery and the left anterior descending coronary artery was imaged. In all 25 patients it was possible to measure by pulsed Doppler the coronary velocity flow pattern, characterized by a typical prevalent diastolic component. Peak diastolic flow velocity was 49.98 +/- 17.30 cm/s and mean diastolic flow velocity was 36.52 +/- 11.91 cm/s. The Doppler pattern of the grafted mammary artery was different from the native mammary flow. This new non invasive imaging technique of the coronary arteries promises to expand the field of diagnostic and experimental echocardiography and brings new insight into the pathophysiology of ischemic heart disease.     

An investigation of ethnic and gender differences in the pharmacodynamics of haloperidol

To observe pulmonary venous flow in dogs, the echocardiographic imaging planes and the techniques for examination, and the validations of anatomic location were investigated. Then, the velocity pattern of pulmonary venous flow was recorded in normal conscious dogs. Six imaging planes were available for observing the right or left caudal lobe pulmonary venous flow with two-dimensional or pulsed Doppler echocardiography. Of these, the left lateral apical 4-chamber view can be applied as standard view, because the pulmonary venous flow and transmitral flow could be recorded in this view simultaneously with small sampling angle. The velocity pattern of pulmonary venous flow demonstrated two forward waves in 19 of 20 dogs examined, with one peak occurring during ventricular systole and another during ventricular diastole. A reversed flow during atrial contraction was also seen in 11 dogs. In the two forward waves, the mean peak velocity and velocity-time integral of ventricular diastolic forward flow were significantly higher than those of systolic forward flow (46.49 +/- 6.79 vs. 31.13 +/- 4.92 cm/s, p < 0.0001 and 8.18 +/- 1.84 vs. 5.14 +/- 0.82 cm, p < 0.0001, respectively). The deceleration time of diastolic forward flow shortened with the increase of heart rate (r = -0.87, p < 0.0001). Pulmonary venous flow in dogs can be observed under transthoracic two-dimensional or pulsed Doppler echocardiography.     

Anatomic variability of rejection in intestinal allografts after pediatric intestinal transplantation

The internal mammary artery is routinely used for coronary artery bypass grafting because of its optimal long-term patency profile. This vessel can be imaged by angiography, but only the proximal tract at the origin from the succlavian artery can be imaged by conventional echography. The aim of our study was to visualize the intrathoracic course of the native and grafted internal mammary arteries by a new ultrasound equipment which allows high-resolution transthoracic color Doppler imaging of the chest wall vessels and coronary arteries. We studied 35 patients, 16 non operated and 19 operated of coronary surgery with the internal mammary artery grafted to the left anterior descending coronary artery. We used a multifrequency 3.5-7 MHz transducer with a small insonating surface, placed at the second-fifth intercostal space at the left and right sternal border, to image the native mammary arteries. The grafted mammary artery was detected at the fourth-fifth left intercostal space 2-4 cm lateral to the sternal border. The native left internal mammary artery was visualized in all 16 non operated patients, and the right internal mammary artery in 14/16 (87%). The native left internal mammary artery peak flow velocity was 41-160 cm/s (mean 81 +/- 34 cm/s), and the mean flow velocity was 28-89 cm/s (mean 45 +/- 17 cm/s). The right internal mammary artery peak flow velocity was 35-153 cm/s (mean 82 +/- 36 cm/s), and mean flow velocity was 21-82 cm/s (mean 46 +/- 22 cm/s). The grafted left internal mammary artery was visualized in 16/19 patients (84%), evaluated at 6 days to 36 months after surgery. Peak diastolic flow velocity ranged from 24 to 80 cm/s (mean 48 +/- 17 cm/s), and mean diastolic flow velocity ranged from 13 to 57 cm/s (mean 33 +/- 11 cm/s). The left anterior descending peak flow velocity distal to the anastomosis was 22-62 cm/s (mean 37 +/- 15 cm/s) and mean flow velocity was 18-53 cm/s (mean 29 +/- 12 cm/s). We conclude that transthoracic color Doppler echocardiography allows to image the native and grafted mammary arteries, with potential clinical applications in the management of patients with coronary artery disease.     

Effect of systemic corticoid and antihistamine alone or in combination on elements of the response to a two dose nasal allergen challenge

Adenosine, an endogenous vasodilator, induces a cerebral vasodilation at hypotensive infusion rates in anaesthetized humans. At lower doses (< 100 micrograms kg-1 min-1), adenosine has shown to have an analgesic effect. This study was undertaken to investigate whether a low dose, causing tolerable symptoms of peripheral vasodilation affects the global cerebral blood flow (CBF). In nine healthy volunteers CBF measurements were made using axial magnetic resonance (MR) phase images of the internal carotid and vertebral arteries at the level of C2-3. Quantitative assessment of CBF was also obtained with positron emission tomography (PET) technique, using intravenous bolus [15O]butanol as tracer in four of the subject at another occasion. During normoventilation (5.4 +/- 0.2 kPa, mean +/- s.e.m.), the cerebral blood flow measured by magnetic resonance imaging technique, as the sum of the flows in both carotid and vertebral arteries, was 863 +/- 66 mL min-1, equivalent to about 64 +/- 5 mL 100 g-1 min-1. The cerebral blood flow measured by positron emission tomography technique, was 59 +/- 4 mL 100 g-1 min-1. All subjects had a normal CO2 reactivity. When adenosine was infused (84 +/- 7 micrograms kg-1 min-1.) the cerebral blood flow, measured by magnetic resonance imaging was 60 +/- 5 mL 100 g-1 min-1. The end tidal CO2 level was slightly lower (0.2 +/- 0.1 kPa) during adenosine infusion than during normoventilation. In the subgroup there was no difference in cerebral blood flow as measured by magnetic resonance imaging or positron emission tomography. In conclusion, adenosine infusion at tolerable doses in healthy volunteers does not affect global cerebral blood flow in unanaesthetized humans.     

Left ventricular diastolic filling alterations in subjects with mitral valve prolapse: a Doppler echocardiographic study

To assess left ventricular diastolic filling in mitral valve prolapse (MVP), we studied 22 patients with idiopathic MVP and 22 healthy controls matched for sex, age, body surface area and heart rate. A two-dimensional, M-mode and Doppler echocardiographic examination was performed to exclude any cardiac abnormalities. The two groups had similar diastolic and systolic left ventricular volumes, left ventricle mass and ejection fraction. Doppler measurements of mitral inflow were: E and A areas (the components of the total flow velocity-time integral in the early passive period of ventricular filling, E; and the late active period of atrial emptying, A), the peak E and A velocities (cm.s-1), acceleration and deceleration half-times (ms) of early diastolic rapid inflow, acceleration time of early diastolic flow (AT), total diastolic filling time (DFT) (ms), and the deceleration of early diastolic flow (cm.s-2). From these measurements were calculate: peak A/E ratio (A/E), E area/A area, the early filling fraction, the atrial filling fraction, AT/DFT ratio. All the Doppler measurements reported are the average of three cardiac cycles selected at end expiration. The mean peak A velocity, A/E velocity ratio, deceleration half time and atrial filling fraction were each significantly higher for subjects presenting a MVP (60 +/- 12 cm.s-1 vs 49 +/- 14, P < 0.008; 98 +/- 13% vs 64 +/- 12%, P < 0.0001; 120 +/- 36 ms vs 92 +/- 11, P < 0.002; 0.45 +/- 0.14 vs 0.36 +/- 0.08, P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of blood flow distal to coronary artery stenoses. Correlations between myocardial positron emission tomography and poststenotic intracoronary Doppler flow reserve

BACKGROUND: Previous studies have correlated quantitative coronary angiographic stenosis severity with positron emission tomography (PET) myocardial perfusion and proximal measurements of intracoronary flow velocities in normal and diseased coronary arteries. The aim of this study was to correlate regional myocardial blood flow (RMBF) derived from [15O]H2O PET with directly measured poststenotic intracoronary Doppler flow velocity data acquired under basal conditions and dipyridamole-induced hyperemia. METHODS AND RESULTS: Eleven consecutive patients 53 +/- 13 years old with ischemic chest pain and isolated proximal left coronary artery stenoses (left anterior descending, 9; left circumflex, 2; mean, 59 +/- 23% diameter stenosis) underwent [15O]H2O myocardial PET and intracoronary Doppler flow velocity studies within 1 week. PET RMBF (mL.g-1.min-1) and myocardial perfusion reserve (MPR) were calculated in poststenotic and normal reference vascular beds. Poststenotic Doppler average peak flow velocities (APV; cm/s) and coronary flow velocity reserve (CFR) were compared with corresponding PET data and quantitative angiographic lesional parameters. PET RMBF and Doppler APV were linearly correlated (r = .60; P < .001), as were poststenotic PET MPR and Doppler CFR (r = .76; P < .0002). Relative coronary flow velocity and MPR ratios between poststenotic and angiographically normal vascular beds were comparably reduced (0.83 +/- 0.25 versus 0.86 +/- 0.21, respectively; P = NS). CONCLUSIONS: Intracoronary Doppler flow velocities acquired distal to isolated left coronary artery stenoses correlated with [15O]H2O PET regional myocardial perfusion and are useful for assessment of the physiological significance of coronary stenoses in humans.     

Comparison of echocardiography with magnetic resonance imaging in the assessment of the athlete's heart

AIM: The purpose of the study was to compare the accuracy of M-mode echocardiography and two different two-dimensional echocardiographic approaches in the assessment of left ventricular mass and volumes in endurance-trained and strength-trained athletes, using magnetic resonance imaging as reference standard. METHODS AND RESULTS: We studied 19 athletes and 10 untrained control subjects, M-mode and two-dimensional echocardiography were compared to magnetic resonance imaging. M-mode echocardiographic left ventricular mass was calculated using the Penn cube convention. Two-dimensional echocardiographic left ventricular mass was calculated using (1) the area-length method as proposed by the American Society of Echocardiography (ASE) and (2) as proposed by Reichek. The best correlation between magnetic resonance imaging and echocardiographic left ventricular mass and volumes was observed with the ASE two-dimensional echocardiographic method. The agreement between them (-3.4 +/- 7.6 g and 18.5 +/- 19.5 ml) was better than between Reichek two-dimensional echocardiography and magnetic resonance imaging (-39.4 +/- 15.4-g and 52.8 +/- 21.7 ml), and demonstrated less random difference than M-mode echocardiography and magnetic resonance imaging (3.2 +/- 21.1 g resp. 15.1 +/- 30.0 ml). CONCLUSION: We conclude that the ASE two-dimensional echocardiographic approach, when using magnetic resonance imaging as a reference standard, was the most accurate estimator of left ventricular mass and volumes in both controls and athletes.     

Flow reversal in the descending aorta: a guide to intraoperative assessment of aortic regurgitation with transesophageal echocardiography

This study assessed the value of biplane transesophageal echocardiographic assessment of diastolic flow reversal in the descending aorta as an alternative to Doppler color flow imaging in determining severity of aortic regurgitation. In 45 patients undergoing cardiac operations, the severity of aortic regurgitation was assessed by semiquantitative grading of the width of the Doppler color flow regurgitant jet relative to the left ventricular outflow tract, and the presence of diastolic flow reversal was assessed with pulsed-wave Doppler measurements at three sites in the descending aorta. In four patients, the diastolic flow reversal method was the only available form of assessment because of inadequate visualization of the left ventricular outflow tract beneath a mitral valve prosthesis. Diastolic flow reversal in the descending aorta was not observed in patients without aortic regurgitation and was always present in patients with severe aortic regurgitation. Aortic valve replacement successfully eliminated descending aortic flow reversal in all 19 patients in whom it was present before valve replacement. Identification of diastolic flow reversal at multiple sites in the descending aorta with biplane transesophageal echocardiography helps to confirm the presence of severe aortic regurgitation and can serve as an alternative method of assessment when visualization of the left ventricular outflow tract is impaired.     

Effect of prosthesis type and size on the hemodynamic response of mitral valve prostheses to exertion

BACKGROUND: Doppler echocardiography is current tool for hemodynamic evaluation of mitral prosthetic heart valves. It's accepted that the area and the gradients by Doppler echocardiography are not influenced at rest by valvular type and valvular size. We evaluated the influence of valvular type, mechanical-biological, and size on exercise hemodynamic of normally-functioning mitral prosthesis. Thirty-seven patients with mitral prosthesis, mean age 56 +/- 10 years, underwent exercise Doppler echocardiography. Peak and mean prosthetic gradient were obtained at rest, during and at maximal exercise with a nonimaging transducer. Mechanical prosthesis were 23 and biological valves 14. Valvular size was less than 26 mm in 7 patients and more than 28 mm in 20 patients. Exercise increased the heart rate from 80 +/- 14 to 143 +/- 22 (p < 0.001), peak gradient from 11.4 +/- 4 to 26.1 +/- 7 mm Hg (p < 0.001) and mean gradient from 4.8 +/- 1 to 13.7 +/- 5 mm Hg (p < 0.001). We found similar peak (11.4 +/- 3 & 11.3 +/- 4) and mean gradient (3.4 +/- 1 & 2.9 +/- 0.7) at rest between mechanical and biological valves; at maximum exercise, peak (26 +/- 7 & 26 +/- 6) and mean gradient (13.9 +/- 6 & 13.2 +/- 4) were also similar. Prosthesis with > 28-mm-size compared with prosthesis < 26-mm-size showed minor peak gradient at second step (21.3 +/- 4 & 26.4 +/- 6, p < 0.05) and at peak exercise (25.4 +/- 7 & 29.8 +/- 8, ns). Hemodynamics on exercise using Doppler echocardiography was not influenced by valvular type (mechanical-biological) in normal mitral prosthesis. However, mitral prosthesis of small size showed worse on hemodynamics exercise than bigger ones.     

Left ventricular diastolic properties of hypertensive patients measured by pulsed tissue Doppler imaging

Examination of left ventricular (LV) diastolic dysfunction in hypertensive patients has been based on parameters obtained from the transmitral flow velocity during pulsed Doppler echocardiography. However, these parameters are affected by loading conditions. We evaluated LV diastolic function along the longitudinal and transverse axes by pulsed tissue Doppler imaging (TDI) in 50 hypertensive (HT) patients and 36 age-matched healthy volunteers (N). Transmitral flow velocity was recorded by pulsed Doppler echocardiography. LV posterior wall motion velocity along the longitudinal and transverse axes also was recorded by pulsed TDI. In both groups, peak early diastolic velocity of the LV posterior wall (Ew) along the transverse axis (N: 15.8+/-5.2 cm/s, HT: 12.2+/-4.4 cm/s) was higher than that along the longitudinal axis (N: 12.7+/-3.1 cm/s, HT: 9.5+/-3.3 cm/s). Peak atrial systolic velocity of the LV posterior wall (Aw) along the longitudinal axis (N: 9.1+/-1.8 cm/s, HT: 9.7 +/-2.6 cm/s) significantly exceeded that along the transverse axis (N: 8.0+/-2.2 cm/s, HT: 8.4+/-2.4 cm/s) in both groups. The Ews were lower and the Aws were higher along both axes in the patient group than in the control group. The time intervals from the aortic component of the second heart sound to the peak of the early diastolic wave (IIA-Ews) along both the transverse (N: 142+/-18 ms, HT: 154+/-19 ms) and longitudinal (N: 151 16 ms, HT: 162+/-20 ms) axes were longer in the patient group. In 29 patients, Ews along both axes correlated negatively (transverse: r = -0.80, P < .0001; longitudinal: r = -0.71, P < .0001) and IIA-Ews correlated positively (transverse: r = 0.81, P < .0001; longitudinal: r = 0.74, P < .001) with the time constant of the LV pressure decay during isovolumic diastole. The Aws along both axes in the 24 patients without pseudonormalization in transmitral flow velocity correlated positively (transverse: r = 0.60, P < .001; longitudinal: r = 0.74, P < .0001) with the LV end-diastolic pressure. In conclusion, LV relaxation and filling along the longitudinal and transverse axes were impaired in many patients with hypertension. Pulsed TDI was useful for evaluating LV diastolic dynamics in this disease.     

Cardiac responses to maximal upright cycle exercise in healthy boys and men

Previous investigations have indicated that children demonstrate a lower cardiac output at a given oxygen uptake during exercise compared with adults. This study compared cardiac responses with maximal upright cycle exercise in 15 boys (mean age 10.9 yr) and 16 men (mean age 30.7 yr) to determine whether this observation reflects differences in size or age-related influences on myocardial function. Stroke volume, aortic peak velocity, and systolic ejection time were measured to peak exercise in all subjects using Doppler ultrasound techniques. No significant differences were observed in resting, submaximal, or peak mean values for these variables relative to body size between the boys and men. Average values for peak stroke index, cardiac index, and peak aortic velocity were 59 (+/-11) mL.m-2, 11.33 (+/-2.32) L.min-1.m-2, and 152 (+/-30) cm.s-1, respectively, for the boys. Respective values for the men were 61 (+/-14) mL.m-2, 11.08 (+/-2.52) L.min-1.m-2, and 144 (+/-24) cm.s-1 (P > 0.05). This study failed to demonstrate evidence of impaired cardiac responses to maximal exercise in prepubertal boys compared with that in adult males.     

Noninvasive assessment of significant left anterior descending coronary artery stenosis by coronary flow velocity reserve with transthoracic color Doppler echocardiography

BACKGROUND: Coronary flow reserve has been considered an important diagnostic index of the functional significance of coronary artery stenosis. With Doppler technique, it has been assessed as the ratio of hyperemic to basal coronary flow velocity (coronary flow velocity reserve [CFVR]) by invasive or semiinvasive methods with a Doppler catheter, a Doppler guide wire, and a transesophageal Doppler echocardiographic probe. Recent technological advancement in transthoracic Doppler echocardiography (TTDE) provides measurement of coronary flow velocity in the distal portion of the left anterior descending coronary artery (LAD) and may be useful in the noninvasive CFVR measurement. The purpose of this study was to evaluate the value of CFVR determined by TTDE for the assessment of significant LAD stenosis. METHODS AND RESULTS: We studied 36 patients who underwent coronary angiography for the assessment of coronary artery disease. The study population consisted of 12 patients with significant LAD stenosis (group A) and 24 patients without significant LAD stenosis (group B). With TTDE, coronary flow velocities in the distal LAD were recorded at rest and during hyperemia induced by intravenous infusion of adenosine (0.14 mg x kg(-1) x min(-1)) under the guidance of color Doppler flow mapping. Adequate spectral Doppler recordings of coronary flow in the distal LAD for the assessment of CFVR were obtained in 34 of 36 study patients (94%). The peak and mean diastolic coronary flow velocities at baseline did not differ between groups A and B (23.6+/-10.3 versus 22.9+/-6.6 cm/s and 16.4+/-8.6 versus 14.5+/-4.0 cm/s, respectively). However, the peak and mean coronary flow velocities during hyperemia in group A were significantly smaller than those in group B (35.6+/-16.3 versus 54.2+/-16.3 cm/s and 24.7+/-13.1 versus 37.9+/-13.0 cm/s, respectively; P<.01). There were significant differences in CFVR obtained from peak and mean diastolic velocity between groups A and B (1.5+/-0.2 versus 2.4+/-0.4 and 1.5+/-0.2 versus 2.6+/-0.4, respectively; P<.001). A CFVR from peak diastolic velocity <2.0 had a sensitivity of 92% and a specificity of 82% for the presence of significant LAD stenosis. A CFVR from mean diastolic velocity <2.0 had a sensitivity of 92% and a specificity of 86% for the presence of significant LAD stenosis. CONCLUSIONS: CFVR determined by TTDE is useful in the noninvasive assessment of significant stenotic lesion in the LAD.     

The impact of ischemic heart disease on main pulmonary artery blood flow patterns: a comparison between magnetic resonance phase velocity mapping and transesophageal color Doppler

OBJECTIVE: To give a detailed evaluation on main pulmonary artery blood velocity patterns, in patients with ischemic heart disease and to provide recommendations for pulsed Doppler sample volume placement, in order to optimize cardiac output estimation. METHODS: Using magnetic resonance phase and esophageal color Doppler velocity mapping in 12 patients with ischemic heart disease and undergoing coronary artery by-pass grafting, very similar data on pulmonary artery blood velocity patterns were provided for comparison with each other. RESULTS: Peak blood velocities were located in the inferior half of the main pulmonary artery cross-sectional area. Early after peak systole the highest velocities shifted towards the superior/left (major curvature) with a simultaneous decrease in velocities inferiorly. The velocity decrease further evolved into retrograde flow to the inferior/right (minor curvature). This feature was significantly enhanced compared to earlier findings in healthy volunteers. The mean temporal blood velocity profiles were asymmetrically skewed, thereby giving unreliable cardiac output estimates based on single point Doppler blood velocity recordings. The error incurred may amount to more than 100% in extreme cases. According to our data, optimal assessment of cardiac output should be based on multiple sample volumes placed along the inferior/right to superior/left diameter. CONCLUSIONS: MR-phase velocity mapping and multiplane transesophageal color Doppler recordings provided similar blood velocity patterns in patients with ischemic heart disease. The skewness of the mean temporal blood velocity profile is enhanced compared with healthy subjects, resulting in error in the assessment of CO by means of pulsed Doppler echocardiography. By using multiple Doppler sample volumes, the error can be minimized.     

Quantification of mitral regurgitation by velocity-encoded cine nuclear magnetic resonance imaging

OBJECTIVES: The feasibility of velocity-encoded cine nuclear magnetic resonance (NMR) imaging to measure regurgitant volume and regurgitant fraction in patients with mitral regurgitation was evaluated. BACKGROUND: Velocity-encoded cine NMR imaging has been reported to provide accurate measurement of the volume of blood flow in the ascending aorta and through the mitral annulus. Therefore, we hypothesized that the difference between mitral inflow and aortic systolic flow provides the regurgitant volume in the setting of mitral regurgitation. METHODS: Using velocity-encoded cine NMR imaging at a magnet field strength of 1.5 T and color Doppler echocardiography, 19 patients with isolated mitral regurgitation and 10 normal subjects were studied. Velocity-encoded cine NMR images were acquired in the short-axis plane of the ascending aorta and from the short-axis plane of the left ventricle at the level of the mitral annulus. Two independent observers measured the ascending aortic flow volume and left ventricular inflow volume to calculate the regurgitant volume as the difference between left ventricular inflow volume and aortic flow volume, and the regurgitant fraction was calculated. Using accepted criteria of color flow Doppler imaging and spectral analysis, the severity of mitral regurgitation was qualitatively graded as mild, moderate or severe and compared with regurgitant volume and regurgitant fraction, as determined by velocity-encoded cine NMR imaging. RESULTS: In normal subjects the regurgitant volume was -6 +/- 345 ml/min (mean +/- SD). In patients with mild, moderate and severe mitral regurgitation, the regurgitant volume was 156 +/- 203, 1,384 +/- 437 and 4,763 +/- 2,449 ml/min, respectively. In normal subjects the regurgitant fraction was 0.7 +/- 6.1%. In patients with mild, moderate and severe mitral regurgitation, the regurgitant fraction was 3.1 +/- 3.4%, 24.5 +/- 8.9% and 48.6 +/- 7.6%, respectively. The regurgitant fraction correlated well with the echocardiographic severity of mitral regurgitation (r = 0.87). Interobserver reproducibilities for regurgitant volume and regurgitant fraction were excellent (r = 0.99, SEE = 238 ml; r = 0.98, SEE = 4.1%, respectively). CONCLUSIONS: These findings suggest that velocity-encoded NMR imaging can be used to estimate regurgitant volume and regurgitant fraction in patients with mitral regurgitation and can discriminate patients with moderate or severe mitral regurgitation from normal subjects and patients with mild regurgitation. It may be useful for monitoring the effect of therapy intended to reduce the severity of mitral regurgitation.     

Simultaneous measurement of pulmonary venous flow by intravascular catheter Doppler velocimetry and transesophageal Doppler echocardiography: relation to left atrial pressure and left atrial and left ventricular function

OBJECTIVES: The aim of our study was to compare measurements of pulmonary venous flow velocity obtained either by transesophageal Doppler echocardiography or by intravascular catheter Doppler velocimetry. Furthermore, the relation among pulmonary venous flow velocity, left atrial compliance and left atrial pressure was evaluated. BACKGROUND: Data about the relation between left atrial pressure and pulmonary venous flow velocity are controversial. METHODS: A total of 32 patients undergoing elective open heart surgery for coronary artery bypass grafting were included prospectively in the study. Pulmonary venous flow velocity (Doppler catheter) and left atrial pressure (microtip pressure transducer) were recorded simultaneously with recordings of pulmonary venous flow velocity obtained by transesophageal Doppler echocardiography. RESULTS: Agreement between Doppler catheter and Doppler echocardiographic measurements of pulmonary venous flow velocity (n = 18 patients) was analyzed using the Bland-Altmann technique. The 95% limits of agreement were -0.16 to +0.11 m/s for systolic peak velocity, -0.14 to +0.09 m/s for diastolic peak velocity and -0.12 to +0.10 m/s for atrial peak velocity. The closest agreement between both methods was found for the ratio of systolic to diastolic peak velocity, the ratio of systolic to diastolic flow duration and the time from Q deflection on the electrocardiogram to maximal flow velocity. Mean left atrial pressure was strongly correlated with the ratio of systolic to diastolic peak velocity (r = -0.829), systolic velocity-time integral (r = -0.653), time to maximal flow velocity (r = 0.844) and the ratio of systolic to diastolic flow duration (r = -0.556). The ratio of systolic to diastolic peak velocity and the time to maximal flow velocity were identified as strong independent predictors of mean left atrial pressure. Left atrial compliance was not found to be an independent predictor of mean left atrial pressure. CONCLUSIONS: Flow velocity in the left upper pulmonary vein can be reliably recorded by transesophageal pulsed wave Doppler echocardiography. Our data reveal further evidence that mean left atrial pressure can be estimated by the pattern of pulmonary venous flow velocity.     

Flow parameters of the normal arterial duct in the fetus

The increasing interest in arterial duct flow patterns in the fetus warrants the establishment of an accurate range of normal flow parameters throughout gestation. We therefore undertook a prospective echocardiographic study of 181 normal fetuses from the 16th to the 40th week of gestation. Adequate Doppler interrogation of the duct was obtained in 71% of the fetuses examined. Peak gradient, mean gradient and flow velocity integral in systole and diastole were digitized. The peak systolic gradient throughout pregnancy measured 2.7 +/- 1.4 mmHg with a slight tendency to increase with gestational age (r = 0.58). The peak ratio, defined as peak systolic gradient divided by peak diastolic gradient (28.1 +/- 14.9), did not vary significantly with gestational age. This time-independent index complements peak systolic flow in the assessment of normal and abnormal ductal flow. The definition of the normal range for ductal flow parameters, based on this relatively large fetal population, should facilitate the accurate diagnosis of fetal duct constriction.     

Chimpanzee (Pan troglodytes) pointing: hand shapes, accuracy, and the role of eye gaze

We have validated a new semiautomated method for quantification of volumetric flow applied to multiplane transesophageal color Doppler mapping. This Doppler technique assumes only the incompressibility of the fluid and includes variations of flow area. By computing velocity vectors across a surface normal to the point of scanning, volumetric flow can be measured independently of the angle of incidence between the ultrasonic beam and the direction of blood flow. Mitral valvular flow rate was measured during surgery by transesophageal color Doppler echocardiography in 27 patients undergoing coronary artery bypass grafting at 45 sets of observations. The results were compared with those obtained by the thermodilution technique. The mean of the differences between the thermodilution technique and color Doppler echocardiography was 0.06 +/- 0.866 L/min for the mitral valvular flows (mean of differences [thermodilution-color Doppler] &/- 2 SDs of differences). Thus mitral valvular volumetric flow measured by this color Doppler method showed a close agreement to the thermodilution technique during surgery.     

Changes in blood flow velocity and diameter of the middle cerebral artery during hyperventilation: assessment with MR and transcranial Doppler sonography

PURPOSE: To compare blood flow velocity changes within the middle cerebral artery (MCA) during hyperventilation, as measured with by both transcranial Doppler sonography and MR imaging, with the diameter of the MCA as measured with MR imaging alone. METHODS: The studies were performed in six healthy volunteers ranging in age from 22 to 31 years (mean, 27 years). Transcranial Doppler sonography was carried out with a range-gated 2-MHz transducer. MR examinations were done on a 1.5-T imaging unit. MR angiography was performed using the time-of-flight technique. MR flow measurements were carried out by using the phase-mapping technique with an ECG-triggered phase-contrast sequence. RESULTS: During hyperventilation, the mean blood flow velocity of the proximal MCA declined by 49.6% +/- 5.7 (mean +/- standard deviation) as measured with Doppler sonography, and by 47% +/- 4.6 as measured with MR flow calculation. The diameter of the MCA (3.4 +/- 0.3 mm) remained unchanged on MR imaging studies (3.3 +/- 0.3 mm). CONCLUSION: We found a good correlation between relative flow velocity changes measured by transcranial Doppler sonography and MR techniques. MR imaging revealed no significant changes in the diameter of the proximal MCA during normal versus hyperventilation. Relative changes in flow velocity in the MCA would thereby reflect relative changes in cerebral blood flow, at least during hyperventilation.