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The noninvasive measurement of left ventricular filling has relied predominantly on radionuclide-derived peak filling rate normalized to end-diastolic volume. Doppler echocardiography also has the ability to measure peak filling rate, but wide application of this technique has been limited by technical errors involved in quantitative echocardiographic determination of mitral anulus cross-sectional area and ventricular volumes. For Doppler echocardiography, normalization of peak filling rate to mitral stroke volume rather than end-diastolic volume permits the derivation of a diastolic filling index that is relatively free of errors caused by geometric assumptions, diameter measurements and sample volume positioning. This normalization process can be achieved by simply dividing early peak filling velocity by the time velocity integral of mitral inflow. To validate this new Doppler echocardiographic filling index, Doppler echocardiographic and radionuclide-derived peak filling rate, both normalized to mitral stroke volume, were compared in 30 patients; there was an excellent correlation (r = 0.91, SEE = 0.88). This variable was not influenced by the position of the sample volume in relation to the mitral apparatus in contrast to early filling velocity, which increased 37%, and early/late filling (E/A) ratio, which increased 43% as the sample volume was moved from the anulus to the tips of the mitral leaflets. In a cohort of 22 normal patients, the mean peak filling rate normalized to mitral stroke volume (SV) was 5.25 +/- 1.47 SV/s. The mean peak filling rate for a subgroup of eight normal patients aged 57 to 89 years (mean 71 +/- 9) was 3.9 +/- 1 SV/s.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Peak filling rate normalized to mitral stroke volume: a new Doppler echocardiographic filling index validated by radionuclide angiographic techniques. 341 92

To evaluate the accuracy of noninvasive determination of stroke volume in infants and children, 28 patients (age range 4 weeks to 19 years) were studied. Stroke volume was calculated according to Teichholtz from M-mode echocardiographic tracings of left ventricular dimensions in 8 subjects. Agreement with thermodilution performed within 60 min of echocardiography was good (r = 0.995, y = 0.91x + 1.59, SEE = 1.8 ml). Since stroke volume correlated to body size we corrected for (height)3. After this correction there was still good agreement to thermodilution (r = 0.88, y = 1.29x-7.13, SEE = 7.1 ml/H3). M-mode echocardiography was then used as a reference method for evaluating two different Doppler methods in the remaining 20 subjects. Continuous wave Doppler stroke distance, calculated from the mean velocity, was combined with aortic root area (Method I), and stroke distance calculated from maximum velocity was combined with the aortic interleaflet area (Method II). Good agreement was found with Method I (r = 0.95, y = 1.01x-0.14, SEE = 8.1 ml) and Method II (r = 0.95, y = 1.04x-1.14, SEE = 8.4 ml). However, when stroke volume was normalized for (height)3, Method I was found to be superior to Method II.
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PMID:Estimation of stroke volume using Doppler echocardiography and left ventricular echocardiographic dimensions in infants and children. 347 99

Although two-dimensional echocardiography has provided accurate measurements of left ventricular ejection fraction, the technique has been limited in the evaluation of diastolic function. First half-filling fraction, representing the difference between mid-diastolic and end-systolic volumes divided by stroke volume, is a recently introduced index of diastolic function. We developed a method for determining half-filling fraction by two-dimensional echocardiography with the use of the average of left ventricular internal diameters measured at the base, middle, and apical third of the ventricular cavity in multiple longitudinal planes. In 27 patients with a wide range of ventricular function, we compared angiographic measurements of half-filling fraction to results obtained by two-dimensional echocardiography. Half-filling fraction measured angiographically averaged (mean +/- SD) 0.58 +/- 0.15 (range 0.26 to 0.77) and measured by two-dimensional echocardiography averaged 0.58 +/- 0.15 (range 0.35 to 0.90). A significant correlation was found between angiographic and echocardiographic half-filling fractions (r = 0.84, SEE = 0.08). Results were similar in the presence or absence of segmental wall motion abnormalities. All seven patients with half-filling fractions below 0.50 by echocardiography had depressed half-filling fractions by angiography; three of these patients had ejection fractions of greater than or equal to 0.55. Thus half-filling fraction can be derived with two-dimensional echocardiography providing a noninvasive assessment of diastolic function.
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PMID:Assessment of left ventricular diastolic filling by two-dimensional echocardiography. 357 4

To assess the severity of outlfow obstruction in patients with aortic valve disease, the aortic valvar area was noninvasively determined in 22 patients with isolated aortic stenosis or combined stenosis and regurgitation. The ejection time (ET), maximal velocity (Vmax), and systolic velocity integral (SVI) of the aortic flow was obtained by continuous wave Doppler ultrasound. Left ventricular stroke volume (SV) was determined by radionuclide angiography, using a counts-based nongeometric technique with individual attenuation correction. Aortic valve area (AVA) was calculated using a modified Gorlin formula; AVA = SV/(71.2 X ET X Vmax), and also by dividing the stroke volume by the systolic velocity integral; AVA = SV/SVI. The two noninvasive determinations correlated closely with the valve areas obtained by invasive measurements; r = 0.95, SEE = +/- 0.13 cm2 by the modified Gorlin formula, and r = 0.94, SEE = +/- 0.14 cm2 by the integration method. The two noninvasive calculations showed almost uniform results; r = 0.98, SEE = +/- 0.09 cm2. In conclusion, aortic valve area can be determined with reasonable accuracy by combining Doppler echocardiography and radionuclide angiography. This noninvasive approach may reduce the need for invasive measurements in patients with suspected aortic valve disease. In addition, radionuclide angiography provides important information about left ventricular function.
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PMID:Noninvasive determination of the valvar area in aortic valve disease by Doppler echocardiography and radionuclide angiography. 358 58

Nuclear magnetic resonance (NMR) imaging is a new, noninvasive approach for imaging the cardiovascular system. Being a three-dimensional technique, NMR imaging has the capability of measuring volumes without the need for assumptions regarding ventricular geometry. In this study, the technique was validated in 19 excised dog hearts, filled with silicone-rubber, imaged using a multislice spin-echo sequence. The volume of the cavity in each slice was calculated from the number of pixels outlined for each slice multiplied by the pixel volume. Ventricular volumes measured by NMR imaging were highly correlated with cast volumes measured by water displacement: right ventricle (RV):RVNMR = 1.05 RVcast - 1.62; r = 0.99, SEE = 0.96 ml; left ventricle (LV):LVNMR = 0.98 LVcast + 0.35, r = 0.98, SEE = 1.48 ml. After validation in casts, NMR imaging volumes were measured in eight living dogs using a multiphasic gated technique to obtain images at 5, 105, 205, 305 and 405 ms after the QRS complex. Cardiac output (CO) and stroke volume (SV) measured by NMR imaging were significantly correlated with thermodilution (TD) measurements (CONMR = 0.63 COTD + 0.51 liters/min; r = 0.78, SEE = 0.57 liters/min; SVNMR = 0.67 SVTD + 1.95 ml; SEE = 5.58 ml). Right and left stroke volumes were closely related (LVSVNMR = 0.9 RVSVNMR + 1.75; r = 0.94, SEE = 4.32 ml), with the slope and intercept of the regression line showing no difference from 1 and 0, respectively. However, volumes determined by NMR imaging underestimated the thermodilution measurements, presumably reflecting the inability to obtain a true systolic image with the present sampling rate.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Measurement of ventricular volumes in the dog by nuclear magnetic resonance imaging. 359 85

Thermodilution cardiac output determinations and multigated equilibrium blood-pool scintigraphy were performed in ten healthy chacma baboons (Papio ursinus). The correlation was moderately good between both the radionuclide and thermodilution stroke volume (r = 0.58, SEE = 3 ml; SVth = 0.78SVr + 15.6 ml) as well as the cardiac output (r = 0.72, SEE = 0.2 liter/min; COth = 0.56 Cor + 2.1 liter/min). The attenuation depth dr as determined by radionuclide techniques was found to correlate well with the radiologically determined values dx (r = 0.8, SEE = 0.4 cm; dx = 0.87dr + 0.72 cm) which validated the depth values used in the calculations.
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PMID:Comparative radionuclide and thermodilution determinations of cardiac output and stroke volume in the baboon (Papio ursinus). 361 60

Current imaging modalities can provide only a qualitative or semiquantitative measure of the severity of aortic regurgitation. Ultrafast computed tomography (CT) has the capability of rapid imaging (17 frames/sec) coupled with high spatial resolution (1.5 mm2). Eight millimeter thick images can be acquired to interrogate simultaneously the right and left ventricles. End-diastolic and end-systolic tomograms can be reconstructed serially from apex to base by Simpson's rule to provide end-diastolic and end-systolic volumes from which the right and left ventricular stroke volumes can be derived. To determine whether the difference between left and right ventricular stroke volume measured with ultrafast CT could be used to estimate the volume of experimentally induced aortic regurgitation, we studied six dogs in which proximal aortic electromagnetic flow probes had been implanted. Varying degrees of aortic regurgitation were induced by manipulation of a basket catheter through the aortic valve. During suspended respiration in the control state in the absence of aortic regurgitation, right and left ventricular stroke volumes measured with ultrafast CT were nearly identical (mean difference 1.0 +/- 1.2 ml [mean +/- SE]). In the presence of varying degrees of aortic regurgitation, regurgitant volume derived by ultrafast CT as the difference between right and left ventricular stroke volumes correlated closely to the regurgitant volume measured by the electromagnetic flow probe (r = .99, slope = .92, y intercept = 0.98 ml, SEE = 1.02 ml, n = 16). Regurgitant fraction also correlated closely to the regurgitant fraction measured by the electromagnetic flow probe (r = .94, slope = .98, y intercept = 0.66%, SEE = 4.73%, n = 16).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Quantitative determination of aortic regurgitant volumes in dogs by ultrafast computed tomography. 362 30

Precise determination of left and right ventricular stroke volumes is limited with conventional imaging techniques. We determined whether right and left ventricular stroke volumes could be precisely measured with cine computed tomography (CT). Cine CT enables simultaneous imaging of the right and left ventricles at an 8 mm slice thickness with a maximal scanning rate of 17 frames/sec (50 msec acquisition intervals). In eight dogs, true right ventricular and left ventricular stroke volumes were determined by dividing thermodilution cardiac output by heart rate and/or with the use of an aortic electromagnetic flow probe implanted over a long term. After at least 5 sec of suspended respiration, cine CT images were acquired during central venous injection of a nonionic contrast agent. Multiple perturbations in stroke volume were induced in each dog by the administration of dobutamine, sodium pentobarbital, or sodium nitroprusside or by coronary artery occlusion. Right and left ventricular stroke volumes were obtained by Simpson's reconstruction of end-diastolic and end-systolic short-axis tomograms from apex to base. The cine CT left ventricular stroke volume (range 11 to 45 ml) correlated highly with the true left ventricular stroke volume (r = .99, slope = 1.01, y intercept = -0.2 ml, SEE = 1.5 ml, n = 25). The cine CT right ventricular stroke volume (range 11 to 34 ml) also correlated highly with the true right ventricular stroke volume (r = .98, slope = 0.9, y intercept = 2.2 ml, SEE = 1.7 ml, n = 15). In 12 studies, the mean difference between nearly simultaneous right and left ventricular stroke volumes by cine CT was 1.1 ml (range 0.1 to 3.2 ml). Calculation of right and left ventricular stroke volumes from data from cine CT were highly reproducible. Intraobserver variability in measurements of right ventricular stroke volume (r = 1.0, slope = 0.99, y intercept = 0.19 ml) and left ventricular stroke volume (r = 1.0, slope = 1.02, y intercept = -0.21 ml) was minimal. Interobserver variability in measurements of right ventricular stroke volume (r = .98, slope = 0.90, y intercept = 1.66 ml) and left ventricular stroke volume (r = .99, slope = 0.97, y intercept = -0.02 ml) was likewise minimal. Thus, precise and highly reproducible measurements of right and left ventricular stroke volumes can be obtained with cine CT.
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PMID:Precision of measurements of right and left ventricular volume by cine computed tomography. 375 97

A number of reports have described different Doppler echocardiographic methods to calculate left ventricular stroke volume and cardiac output, but the clinical application of the noninvasive measurements of cardiac function remains in the early stages of development. This slow dissemination may be partly explained by the varying success of these ultrasound methods in determining accurate left ventricular stroke volume. The purpose of this study was to improve the simplicity and accuracy of Doppler stroke volume determination so that it could be more easily applied to patient management. Stroke volume was measured using the product of the integral of aortic velocity obtained by continuous wave Doppler technique and the M-mode tracing of the aortic valve, validating the data against cardiac output obtained by thermodilution technique in 41 patients (r = 0.95, SEE = 7 cc). Intra- and interobserver variability was between 9 and 11%. The results of different sampling sites and the temporal relation between Doppler and thermodilution measurements were also studied. Analysis of 21 patients who had M-mode and two-dimensional echocardiographic studies of the aortic root revealed that the method using M-mode measurement of aortic valve area was most accurate in determining left ventricular stroke volume (r = 0.94, SEE = 10 cc), stroke volume being overestimated when area measurements of the ascending aorta were used. In conclusion, maximal ascending aortic velocity determined by continuous wave Doppler echocardiography with M-mode measurement of aortic valve area can be used to calculate left ventricular stroke volume and cardiac output. The simplicity and practicality of this method should enhance the clinical application of Doppler echocardiography as a noninvasive monitoring technique.
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PMID:Measurement of left ventricular stroke volume using continuous wave Doppler echocardiography of the ascending aorta and M-mode echocardiography of the aortic valve. 379 13

In 30 patients with aortic stenosis, 14 of whom also had significant aortic regurgitation, the velocities in the stenotic jet (V') and below the valve (V) were recorded by Doppler ultrasound. With two-dimensional echocardiography, two subvalvular areas (A) were calculated from leading-to-leading edge ("large") and trailing-to-leading edge ("inner") diameter measurements. The aortic valve area was calculated by the equation of continuity (A' = A X peak V/peak V') and by calculating stroke volume below the valve [A X integral of V (t) and dividing by the integral of V' (t) (= A"). Based on cardiac output estimations from single-plane angiographic images, Gorlin's formula was used to calculate invasive valve areas. In patients with no or mild aortic regurgitation a second invasive estimate was based on cardiac output measured by the Fick method. The best correlation was found when A' (with "large" diameter) was compared with invasive results based on cardiac output measured by the Fick method (r = .89, SEE +/- 0.12, n = 16); the worst was found when A" (with "large" diameter) was compared with invasive results based on cardiac output measurements by single-plane angiography (r = .80, SEE +/- 0.20, n = 30). The results indicate that valve area in patients with aortic stenosis can be reliably estimated noninvasively, even in those with significant aortic regurgitation.
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PMID:Noninvasive estimation of valve area in patients with aortic stenosis by Doppler ultrasound and two-dimensional echocardiography. 389 62

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