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The purpose of this study was to assess the clinical utility of pulsed Doppler echocardiography in the determination of regurgitant fraction in patients with aortic regurgitation. Therefore, in 33 unselected consecutive patients with aortic regurgitation, and in 16 patients without heart disease Doppler echocardiography was performed to measure blood flow at the aortic and pulmonary valve. The regurgitant blood flow (RBV) was calculated as the difference of the stroke volumes measured at the aortic and pulmonary valve. The regurgitant fraction (RF) was computed as RBV/aortic flow. At cardiac catheterization RBV and RF were calculated from the left ventricular angiographic stroke volume and the stroke volume measured by thermodilution technique. Four patients were excluded because of technically poor left-ventricular angiograms. In eight patients with aortic regurgitation Doppler measurement of RBV and RF was impossible. The correlations between the invasive and the Doppler data were significant in 21 patients with aortic regurgitation (RBV: r = 0.87, SEE = 16.1 ml; RF: r = 0.90, SEE = 8.1%). However, the RF (41.6 +/- 17.6%) was overestimated by Doppler echocardiography (46.0 +/- 17.9%; p les than 0.021). In the control group RBV ranged between -8.1 ml and 10.5 ml and RF between -13.3% and 7.4%. Thus, pulsed Doppler echocardiography is clinically useful in determination of the regurgitant fraction in about 70% of patients with pure aortic regurgitation. The Doppler method, however, is limited in the diagnosis and quantification of mild aortic regurgitation.
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PMID:[Doppler echocardiography measurement of the regurgitation fraction in patients with aortic valve insufficiency]. 262 19

The spatial distribution of simulated regurgitant jets imaged by Doppler color flow mapping was evaluated under constant flow and pulsatile flow conditions. Jets were simulated through latex tubings of 3.2, 4.8, 6.35 and 7.9 mm by varying flow rates from 137 to 1,260 cc/min. Color jet area was linearly related to flow rate at each orifice (r = 0.96, SEE = 3.4; r = 0.99, SEE = 1.6; r = 0.97, SEE = 2.3; r = 0.97, SEE = 3.2, respectively), but significantly higher flow rates were required to maintain the same maximal spatial distribution of the jet at the larger regurgitant orifices. Constant flow jets were also simulated through needle orifices of 0.2, 0.5 and 1 mm, with a known total volume (5 cc) injected at varying flow rates and with differing absolute volumes injected at the same flow rate (0.2, 1.0 and 2.0 cc/s, respectively). Again, maximal color jet area was linearly related to flow rate at each orifice (r = 0.97, SEE = 2.3; r = 0.97, SEE = 2.4; r = 0.92, SEE = 3.9, respectively), but was not related to the absolute volume of regurgitation. Color encoding of regurgitant jets on Doppler color flow maps was demonstrated to be highly dependent on velocity and, hence, driving pressure, such that color encoding was obtained from a constant flow jet injected at a velocity of 4 m/s through an orifice of 0.04 mm diameter with flow rates as low as 0.008 cc/s. Mitral regurgitant jets were also simulated in a physiologic in vitro pulsatile flow model through three prosthetic valves with known regurgitant orifice sizes (0.2, 0.6 and 2.0 mm2). For each regurgitant orifice size, color jet area at each was linearly related to a regurgitant pressure drop (r = 0.98, SEE = 0.15; r = 0.97, SEE = 0.20; r = 0.97, SEE = 0.23, respectively), regurgitant stroke volume (r = 0.77, SEE = 0.55; r = 0.94, SEE = 0.30; r = 0.91, SEE = 0.41, respectively) and peak regurgitant flow rate (r = 0.98, SEE = 0.16; r = 0.97, SEE = 0.21; r = 0.93, SEE = 0.37, respectively), but the spatial distribution of the regurgitant jets was most highly dependent on the regurgitant pressure drop. Jet kinetic energy calculated from the summation of the individual pixel intensities integrated over the jet area was closely related to driving pressure (r = 0.84), but integration of the power mode area times pixel intensities provided the best estimation of regurgitant stroke volume (r = 0.80).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Doppler color flow mapping of simulated in vitro regurgitant jets: evaluation of the effects of orifice size and hemodynamic variables. 264 15

We studied 16 patients with chronic aortic insufficiency to compare a method for measuring regurgitant volume with color Doppler flow mapping to stroke count ratio determined by radionuclide ventriculography and to ventricular volumes assessed by two-dimensional echocardiography. A real-time color flow map of the left ventricular was obtained from an apical two- and five-chamber view and the maximal mosaic pattern of diastolic turbulent flow was planimetered as a reflection of the maximal regurgitant volume using biplane Simpson's rule. The maximal Doppler regurgitant volume evaluated by color Doppler flow mapping correlated with the stroke count ratio measured by scintigraphy (r = 0.86, SEE = 11 cc). There were significant relationships between maximal regurgitant volume measured by color Doppler and echocardiographic left ventricular end-diastolic volume (r = 0.88), left ventricular end-systolic volume (r = 0.77), and left ventricular mass (r = 0.71). Patients with larger regurgitant volumes tended to have a larger left ventricular end-diastolic volume-to-mass ratio (r = 0.56). Thus maximal aortic regurgitant volume can be estimated noninvasively with color Doppler flow mapping. The measurement appears to relate to left ventricular morphologic changes occurring in this condition and it may prove to be useful in assessing patients with chronic aortic insufficiency and in determining their long-term management.
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PMID:Value of color Doppler estimation of regurgitant volume in patients with chronic aortic insufficiency. 271 70

The orifice area was non-invasively assessed in 19 patients with mitral or mitral and tricuspid stenosis by combined cross-sectional and Doppler echocardiography. Stroke volume was calculated as the product of aortic or pulmonic cross-sectional area and the time velocity integral of the flow across that valve, and the stenotic valve area was obtained as the stroke volume divided by the time velocity integral of the stenotic valve. In addition, the mitral valve area was estimated by the pressure half-time method of Hatle et al. The non-invasive determinations were compared with those calculated by the Gorlin formula at cardiac catheterization. The valve area obtained by combined cross-sectional and Doppler echocardiography showed a close correlation with the Gorlin area, r = 0.90, SEE = 0.13 cm2, n = 20. In contrast, the valve area estimated by the pressure half-time method showed only a moderate correlation with the Gorlin area, r = 0.68, SEE = 0.38 cm2, n = 18, and estimates by this method tended to significantly overestimate the Gorlin area. In conclusion, non-invasive valve area determinations based on combined cross-sectional and Doppler echocardiography can be used to accurately quantify the severity of the lesion in patients with atrioventricular valve stenosis, while determinations by the pressure half-time method may show errors of a magnitude that limits its clinical applicability.
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PMID:Doppler echocardiographic assessment of the valve area in patients with atrioventricular valve stenosis by application of the continuity equation. 272 84

The purpose of this study was to assess the accuracy and clinical utility of pulsed Doppler echocardiography in determining the regurgitant fraction in patients with pure mitral regurgitation. In 30 unselected consecutive patients with mitral regurgitation and in 20 patients without valvular heart disease pulsed Doppler echocardiography was performed to measure blood flow at the mitral and aortic valve. The regurgitant blood volume was calculated as the difference of the stroke volumes measured at the mitral and aortic valve. The regurgitant fraction was computed as regurgitant blood volume/mitral flow. By cardiac catheterization regurgitant blood volume and regurgitant fraction were obtained from the left ventricular angiographic stroke volume and the stroke volume measured by thermodilution. Five patients were excluded because of technically poor left ventricular angiograms. In 4 patients with mitral regurgitation measurement of the regurgitant blood volume and regurgitant fraction was impossible by Doppler because of poor ultrasound signal quality. In 21 patients with mitral regurgitation the correlations between the invasive and the Doppler measurements were significant (regurgitant blood volume: r = 0.89, SEE = 20.9 ml; regurgitant fraction: r = 0.91, SEE = 7.1%). However, the mean percent error of the regurgitant fraction measurement (12.0 +/- 11.6%) was smaller than of the regurgitant blood volume measurement (24.9 +/- 17.0%). In the control group the regurgitant blood volume ranged between -25.1 ml and 11.6 ml and the regurgitant fraction between -17.7% and 12.4%. Thus, pulsed Doppler echocardiography is clinically useful in determination of the regurgitant fraction in 84% of unselected adult patients with pure mitral regurgitation. The Doppler method is limited in the diagnosis and quantification of mild regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Doppler echocardiography quantification of the regurgitant blood volume in patients with mitral valve insufficiency]. 279 56

The stenotic mitral valve area is a major determinant of the atrioventricular pressure-flow relation, and mean atrioventricular pressure gradient is proportionate to the square of mean flow rate. In the absence of obstruction, this relation is linear. The effect of the normal mitral valve area on this pressure-flow relation has not been previously examined. Pulsed Doppler studies of transmitral flow were performed simultaneously with thermodilution cardiac outputs in 25 patients in sinus rhythm and with no valvular disease. Mean flow rate was determined as thermodilution stroke volume/diastolic filling period measured by Doppler. Several instantaneous pressure gradients were estimated from multiple velocity measurements using the modified Bernoulli equation and were plotted against time. Mean pressure gradient was estimated by dividing the area under the pressure-time curve by the diastolic filling period. Average and standard deviation of mean flow rate and pressure gradient was 223 +/- 70 ml/s and 1.4 +/- 0.8 mm Hg, respectively. There was an excellent linear correlation between these 2 parameters (r = 0.91, SEE = 30 ml/s). This confirms the linear relation of mean pressure gradient to mean flow rate in the absence of obstruction. The excellent correlation, obtained without considerations of individual variations of valve area, suggests that this relation is independent of valve area, under normal physiologic conditions.
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PMID:Pressure-flow relations across the normal mitral valve. 295 Jul 51

Few studies have examined the aerobic demand of backstroke swimming, and its relation to body morphology, technique, or performance. The aims of this study were thus to: i) describe the aerobic demand of backstroke swimming in proficient swimmers at high velocities; ii) assess the effects of body size and stroke technique on submaximal and maximal O2 costs, and; iii) test for a relationship between submaximal O2 costs and maximal performance. Sixteen male competitive swimmers were tested during backstroke swimming at velocities from 1.0 to 1.4 m.s-1. Results showed that VO2 increased linearly with velocity (m.s-1) following the equation VO2 = 6.28v - 3.81 (r = 0.77, SEE/Y = 14.9%). VO2 was also related to the subjects' body mass, height, and armspan. Longer distances per stroke were associated with lower O2 costs, and better maximal performances. A significant relation was found between VO2 at 1.1 m.s-1, adjusted for body mass, and 400 m performance (r = -0.78). Submaximal VO2 was also related to reported times for 100 m and 200 m races. Multiple correlation analyses indicated that VO2 at 1.1 m.s-1 and VO2max accounted for up to 78% of the variance in maximal performances. These results suggest that the assessment of submaximal and maximal VO2 during backstroke swimming may be of value in the training and testing programs of competitive swimmers.
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PMID:The aerobic demand of backstroke swimming, and its relation to body size, stroke technique, and performance. 320 65

Continuous wave (CW) Doppler ultrasound has facilitated accurate estimates of pressure gradient (PG) across a stenotic valve. However, the severity of stenosis cannot be assessed using PG alone because it is dependent on actual flow across the valve. In this study, Doppler techniques were used to predict PG and aortic valve areas (AVA) in adults with aortic stenosis (AS). Fifty-four adult patients undergoing cardiac catheterization for suspected AS were prospectively evaluated. There were 28 men and 26 women, who ranged in age from 25 to 68 years with a mean of 56 years. These Doppler ultrasound studies were performed using a 2 MHz transducer and an Aloka SSD-730. With CW Doppler ultrasound, the highest velocities of the aortic jet were recorded from an apical approach. Left ventricular outflow flows were recorded about 1.0-1.5 cm below the aortic annulus using high PRF. Doppler waveforms were analyzed for the AT/ET (AT: acceleration time, ET: ejection time), and Doppler PG was calculated from the maximum velocity (V) of the aortic jet based on a modified Bernoulli equation (PG = 4V2), and aortic valve area was obtained using the continuity equation-(AVA = left ventricular outflow tract stroke volume divided by AS jet velocity integral). These data were compared with hemodynamic data obtained from cardiac catheterization. The following results were obtained: 1. In eight patients with substantial aortic regurgitation, whose maximum catheter PG were from 20 to 45 mmHg, the AT/ET was less than 0.30. The ratio of AT/ET correlated with the peak velocity of the aortic jet (r = 0.88) and the maximum PG (r = 0.87) obtained from cardiac catheterization. 2. In 46 patients with AS, the maximum PG by CW Doppler showed an excellent correlation with maximum catheterization PG (r = 0.97, SEE 6 mmHg), and the mean PG as calculated by the two techniques also disclosed a good correlation (r = 0.97, SEE 5.4 mmHg).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Severity of aortic stenosis assessed by Doppler techniques]. 333 19

This study was undertaken to analyze the diagnostic value of Doppler echocardiographic determination of pressure gradient and valve orifice area for the evaluation of balloon valvuloplasty in mitral stenosis as well as the echocardiographic assessment of calcification, leaflet motion and the subvalvular apparatus for characterization of the most favorable morphologic prerequisites for this procedure. Doppler echocardiographic studies were performed in 24 patients with mitral stenosis, 21 women and three men, age range from 29 to 79 years, mean age 55 years, one day before and after balloon valvuloplasty and the results were compared with invasively-determined hemodynamic measurements. The Doppler echocardiographic determination of the mean pressure gradient before and after balloon valvuloplasty was carried out with the modified Bernoulli equation from the velocity profile of the stenotic jet and calculation of the mitral valve orifice area using the pressure half-time method. Echocardiographic assessment of valve morphology and motion was based on two-dimensional echocardiographic cross-sectional images. Calcification, as observed in the parasternal cross-sectional image, was classified as absent (grade 0), slight to moderate (grade 1) or severe (grade 2). Motion of the valve leaflets, as judged from the apical four- and two-chamber views, was assigned one of five grades taking into consideration the motion of the bodies of both leaflets from the systolic baseline position as less than 10 degrees, between 10 and 45 degrees and more than 45 degrees. The subvalvular apparatus, that is the chordae and the papillary muscles, were graded as unremarkable (grade 0), slightly altered (grade 1) and markedly altered (grade 2). Using a score derived by adding the grade of these three criteria, a formal value between 0 and 8 was calculated. Hemodynamic measurements were carried out with standard techniques employing simultaneous registrations of left atrial and left ventricular pressure for evaluation of the mean diastolic pressure gradient. Determination of the stroke volume was based on biplane left ventriculograms using Simpson's rule. The valve orifice area was calculated according to the Gorlin formula. Dilatation was carried out with a Bifoil (12F, balloon diameter 2 X 19 mm) or Trefoil (10F, 3 X 12 mm) valvuloplasty catheter. After PTVP, on comparison of the Doppler-echocardiographically determined pressure gradient (5.7 +/- 1.9 mm Hg) with that determined invasively (6.4 +/- 3.2 mm Hg) there was a moderate correlation (n = 19, r = 0.74, SEE = 1.3 mm Hg) where the noninvasively-determined values, in general, were smaller.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Doppler echocardiographic findings before and after balloon catheter valvuloplasty in mitral stenosis]. 337 19

Stroke volume and cardiac output (CO) can be determined noninvasively by means of the pulsed Doppler technique to measure blood flow velocities in specified regions of the heart or neighboring great vessels along with 2D-echocardiographic imaging to measure the diameter of vessels or valve orifices. Disadvantages of the transthoracic approach, such as precordial inaccessibility and instability of the probe position, have prevented the continuous application of pulsed Doppler echocardiography during surgery. Recently, we presented a new technique using the transesophageal approach with combined pulsed Doppler measurements and 2D-echocardiographic imaging. This study was designed to assess the feasibility of transesophageal pulsed Doppler echocardiography (TDE) for CO measurements during surgery and to test the method for accuracy against the thermodilution technique (TD) as well as evaluate its ability to track dynamic CO changes during general anesthesia. Transmitral and pulmonary artery flow analysis using TDE was performed in 35 adult patients undergoing a variety of surgical procedures under general anesthesia. For the transesophageal approach we used the prototype of a new 5-MHz phased array transducer with 64 elements fixed at the distal end of a 9 mm gastroscope. The mitral valve flow methods combined the velocity of transmitral flow at the mitral anulus with the cross-sectional area of the anulus calculated from its diameter at middiastole, while the pulmonary flow method combined the velocity of pulmonary artery flow with the cross-sectional area of the vessel calculated from its diameter during early systole. High-resolution 2D-echocardiograms of the mitral valve allowed accurate diameter measurements of the mitral valve orifice in all patients. A fixed esophageal transducer position behind the left atrium enabled continuous transmitral Doppler recordings of invariably high quality to be made. Regression analysis of TDE-CO vs. TD-CO for 50 measurements in 27 patients yielded a good correlation (r = 0.95, y = 0.95x + 0.42, SEE = 0.34 l/min). Use of halothane in 8 further patients resulted in a 21.0 +/- 5.9% and 37.3 +/- 11.7% decrease of TDE-CO at 1.0 MAC and 1.5 MAC, respectively. Transesophageal images adequate to determine the cross-sectional area of the pulmonary artery could be obtained in 16 of 27 (59.3%) patients. CO determined by the TDE pulmonary flow method (28 measurements in 16 patients) correlated with the TD-CO, with an r value of 0.91 and SEE 0.49 l/min.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Intraoperative determination of heart time volume with transesophageal pulsed Doppler echocardiography]. 340 98


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