Quantitative evaluation of cineaortography in the assessment of aortic regurgitation

Cineaortography, quantitative biplane left ventricular angiocardiography and Fick cardiac output studies were performed in 69 patients with aortic regurgitation to evaluate the usefulness of the aortogram in quantitating regurgitation. Thirteen patients had coexistent aortic stenosis and 12 had coexistent mitral stenosis. Patients with concomitant mitral regurgitation were excluded because their aortic regurgitant flow cannot be separately quantified with biplane ventriculography. Twenty-eight other patients without valvular regurgitation were also studied to assess further the accuracy of the quantitative ventriculography, and the stroke volumes derived from Fick and angiographic methods were found to correlate well (r = 0.97). Aortic regurgitation in the 69 patients, graded on a 1 to 5 scale from the aortogram, correlated significantly with the percent and volume of regurgitation (r = 0.56 and 0.65, P < 0.01), respectively). However, there was a wide range in amount of regurgitant flow within the aortographic grades, especially in grades 4 and 5, and there was considerable overlap between the grades. The degree of aortic regurgitation was more commonly overestimated than underestimated from the aortogram, but the correlation tended to be better in the patients with a large end-diastolic volume and normal ejection fraction and without aortic or mitral stenosis.     

A new approach to noninvasive evaluation of aortic regurgitant fraction by two-dimensional Doppler echocardiography

The aortic regurgitant fraction was estimated noninvasively in 20 patients with aortic regurgitation from systolic aortic and pulmonary volume flow determined by duplex Doppler echocardiography. By assuming that an excess of the aortic volume flow (AF) compared with the pulmonary volume flow (PF) is due to aortic regurgitant flow, the aortic regurgitant fraction (RF) was calculated as follows: RF(%) = (AF - PF)/AF X 100. The aortic and pulmonary volume flows were determined as products of systolic integrals of ejection flow velocities and cross-sectional areas of the left and right ventricular outflow tracts, respectively. The Doppler estimate of the regurgitant fraction was compared by semiquantitative grading (1+ to 4+) by cineaortography and with the measurement of regurgitant fraction by catheter technique. The mean Doppler-determined aortic regurgitant fraction was 2.4% for normal subjects, 28.0% for the patients with 1+, 32.6% for the patients with 2+, 53.3% for the patients with 3+, and 62.4% for the patients with 4+. A fair correlation was found between Doppler estimates of regurgitant fraction and semiquantitative cineaortographic grades (r = .80, p less than .01). In the patients without associated mitral regurgitation, a close correlation was observed between Doppler and catheter estimates of regurgitant fraction (r = .96, p less than .01; y = 1.0x - 0.08). In the patients with associated mild mitral regurgitation, however, Doppler estimates of regurgitant fraction substantially underestimated those determined by the conventional catheter technique, which cannot separately quantitate the aortic regurgitant fraction in the presence of mitral regurgitation. These observations indicate that the proposed Doppler technique provides a useful method to evaluate the aortic regurgitant fraction specifically regardless of the presence of associated mitral lesions.     

Non-invasive quantification of aortic regurgitation by Doppler echocardiography.

This study was undertaken to assess the contribution of Doppler echocardiography to the quantification of aortic valve regurgitation. Ultrasound examination was performed by recording aortic arch blood flow from the suprasternal notch. A non-invasive index of valve regurgitation was obtained by calculating the ratio between the maximal amplitude of forward flow during systole and the amplitude of retrograde flow during diastole measured at the onset of the R wave of the electrocardiogram. This index was compared with semiquantitative data derived from supravalvular aortography in 93 patients. In pure aortic regurgitation (67 patients) the results showed a high correlation coefficient between Doppler and angiographic estimates. In cases of associated aortic valve stenosis there were problems in the accurate estimation of systolic blood flow which led to global overestimation in general of the degree of regurgitation and considerable lack of precision in individual patients. But in general Doppler echocardiography appeared to be a successful technique to quantify pure aortic regurgitation.     

Effective aortic regurgitant orifice area: description of a method based on the conservation of mass

The natural history of aortic regurgitation is incompletely understood in part because of the lack of a simple method to estimate the defect size. A method of determining the effective regurgitant orifice area that combines Doppler catheter and Doppler echocardiographic techniques and is based on the principle of conservation of mass (the continuity equation) is described. To validate the application of the Doppler catheter system for measuring regurgitant supravalvular diastolic flow, an in vitro model of retrograde aortic flow was used. These studies indicated that measurements of supravalvular retrograde velocity with the Doppler catheter accurately reflect retrograde diastolic velocity when the aorta is less than 4.8 cm in diameter. Twenty-three patients undergoing cardiac catheterization were studied; 20 of these patients had aortic regurgitation. Retrograde supravalvular diastolic velocity was determined from a Doppler catheter positioned above the aortic valve. The effective regurgitant orifice area was calculated with use of the Doppler catheter-derived regurgitant volume and mean transvalvular diastolic velocity as determined by either catheterization or continuous wave Doppler echocardiography. The catheterization-derived regurgitant orifice area increased with the angiographic grade of as follows: 1+ (0.04 to 0.10 cm2), 2+ (0.15 to 0.49 cm2), 3+ (0.29 to 1.11 cm2) and 4+ (1.24 to 1.33 cm2). By combining Doppler catheter, echocardiographic and cardiac catheterization techniques, the effective aortic regurgitant orifice area may be estimated; this hydrodynamic area correlates with grading by supravalvular aortography. Calculation of this area provides a quantitative alternative to aortography for estimating the severity of aortic regurgitation but should be used with caution in patients with a markedly dilated aorta.     

Dynamics of mitral regurgitation during nitroglycerin therapy: a Doppler echocardiographic study

Seven patients with decompensated chronic heart failure and functional mitral regurgitation were studied before and during administration of nitroglycerin at a mean dose of 42 micrograms/min (range 20 to 90 micrograms/min). Forward aortic flow obtained by pulsed Doppler increased significantly from 35 +/- 8 to 45 +/- 9 ml/beat (p less than 0.001) and correlated well with the cardiac output measured by thermodilution technique (r = 0.8). Whereas regurgitant mitral volume calculated from the difference between echocardiographic total stroke volume and forward aortic flow decreased significantly from 19 +/- 9 to 3 +/- 3 ml/beat (p less than 0.001), peak velocity of mitral regurgitant flow increased from 4.1 +/- 0.9 to 4.4 +/- 1.0 m/sec (p less than 0.05). The decrease in effective mitral regurgitation area derived from a modified Gorlin formula average 80%. Accordingly, in patients with decompensated chronic heart failure and functional mitral regurgitation, nitroglycerin decreases mitral regurgitant area substantially, and thus almost abolishes mitral regurgitation despite an increase in systolic pressure gradient between left ventricle and atrium. Moreover, the increase in forward flow can be entirely accounted for by the reduction in mitral regurgitant flow.     

Non-invasive quantification of aortic regurgitation by Doppler echocardiography

This study was undertaken to assess the contribution of Doppler echocardiography to the quantification of aortic valve regurgitation. Ultrasound examination was performed by recording aortic arch blood flow from the suprasternal notch. A non-invasive index of valve regurgitation was obtained by calculating the ratio between the maximal amplitude of forward flow during systole and the amplitude of retrograde flow during diastole measured at the onset of the R wave of the electrocardiogram. This index was compared with semiquantitative data derived from supravalvular aortography in 93 patients. In pure aortic regurgitation (67 patients) the results showed a high correlation coefficient between Doppler and angiographic estimates. In cases of associated aortic valve stenosis there were problems in the accurate estimation of systolic blood flow which led to global overestimation in general of the degree of regurgitation and considerable lack of precision in individual patients. But in general Doppler echocardiography appeared to be a successful technique to quantify pure aortic regurgitation.     

Doppler assessment of aortic regurgitation. Correlation with hemodynamics and angiography

The Doppler method by permitting assessment of transvalvular blood flow velocity has provided a direct means to interrogate aortic regurgitant flow. Pulsed Doppler permits detection of disturbed diastolic flow by sampling proximal to the aortic valve in the outflow tract and is highly sensitive for diagnosis of aortic regurgitation (AR). For semi-quantitative assessment of the severity, left ventricular (LV) mapping can be performed and a ratio of the area of retrograde diastolic to antegrade systolic flow in the descending aorta can be used. According to the continuity principle, it should be possible to estimate regurgitant fraction by examination of forward flows from two different sites, one representative of forward output and one of total left ventricular output, but this method has not yet been sufficiently validated. Continuous wave (CW) Doppler is nearly as sensitive for detection of aortic regurgitation as pulsed wave (PW) Doppler. Signal strength of regurgitant jet provides an indirect clue to its severity: generally a strong signal indicates moderate to severe degree, a weak signal is associated with mild degrees of regurgitation. The spectral outline of regurgitant jet velocity is determined by instantaneous pressure difference between aortic root and the left ventricle during diastole and an indirect clue to severity of aortic regurgitation is provided by the slope of the curve. A steeper slope or shorter velocity half-time is associated with more severe degrees of regurgitation and vice versa. However, there is considerable scatter in this correlation for any given grade of severity of aortic regurgitation, providing a limited predictive value.(ABSTRACT TRUNCATED AT 250 WORDS)     

Left ventricular dimensions and dynamics of filling in patients with gallop heart sounds

Left ventricular dimensions and the dynamics of filling were measured in sixteen patients with ventricular gallop sounds and in one normal subject with a physiologic third sound. From biplane angiocardiograms left ventricular volume, mass, circumferential wall stress, ejection fraction and peak diastolic filling rate were determined. Patients were divided into two groups according to ejection fraction. Group I with ejection fraction ranging from 0.48 to 0.68 consisted of six patients with aortic and/or mitral regurgitation. Group II with ejection fraction ranging from 0.11 to 0.27 consisted of ten patients with myocardial dysfunction. Peak filling rates were as follows: normal subject 346 ml/sec, group I 478 to 1,352 ml/sec (mean 806 ml/sec) and group II 84 to 604 ml/sec (mean 362 ml/sec). When normalized for end-diastolic volume, ratios of peak filling rate to end-diastolic volume were as follows: normal subject 3.2, group I 2.0 to 3.9 and group II 0.4 to 1.5. Patients with higher peak filling rates had lower stress values (24 to 151 gm/cm², mean 50 gm/cm²) when wall stress was measured at the time of peak filling rate in early diastole than patients in group II (36 to 242 gm/cm², mean 116 gm/cm²). An exception was one patient with acute mitral regurgitation who possessed an elevated filling rate and wall stress value. Patients in group I had louder systolic murmurs and distinctly better prognosis than those in group II. Therefore, in the presence of an enlarged left ventricle, a protodiastolic gallop associated with a prominent systolic regurgitant murmur would suggest a more favorable prognosis than a gallop accompanied by a soft or absent systolic murmur.     

Quantitative assessment by Doppler echocardiography of pulmonary or aortic regurgitation

This study quantitates semilunar valve regurgitation by Doppler measurement of flows. The patients selected had single semilunar valve regurgitation; the other semilunar valve was normal. For the regurgitant valve, forward and reverse flows were measured in the great vessel distal to the abnormal valve, and reverse flow was subtracted from total forward flow to yield net flow. Net flow was compared with forward flow distal to the normal semilunar valve. If all values were computed accurately, net flow should equal forward flow distal to the normal semilunar valve. Twenty patients were studied and 18 had satisfactory recordings. Mean flow in the normal great vessel (3,511 ml/min) was not significantly different from mean net flow in the vessel with the abnormal valve (3,590 ml/min). The correlation coefficient for the paired flow measurements was +0.91 (685 ml [standard error of the estimate]). The slope of the relation was 0.88 and the intercept was 502 ml. Percent regurgitation varied from 29 to 73% and the percentage generally corresponded to clinical estimates. It is concluded that this method, which includes an internal control for each patient, is useful and reasonably accurate for clinical use in patients with pulmonary regurgitation, and appears clinically useful in some patients with aortic regurgitation.     

Striking effect of left ventricular high filling pressure with mitral regurgitation on mitral annular velocity during early diastole. A study using colour M-mode tissue Doppler imaging.

AIMS: To evaluate the effect of considerably high left ventricular filling pressure with mitral regurgitation on mitral annular velocity during early diastole. SUBJECTS: Two hundred and forty-three patients who underwent cardiac catheterization for evaluation of chest pain. METHODS: Mitral annular velocity during early diastole was measured by colour M-mode tissue Doppler imaging. Patients were divided into the following three groups according to the cardiac catheterization data. Group A (n=147): patients having left ventricular relaxation time constant tau<46 ms and left ventricular end-systolic volume index <38 ml m(-2); group B (n=88): patients having tau>or=46 ms and/or end-systolic volume index >or=38 ml m(-2); group C (n=8): patients having mean pulmonary capillary wedge pressure >or=16 mmHg in addition to tau>or=46 ms and end-systolic volume index >or=38 ml m(-2). RESULTS: Mitral annular velocity during early diastole was significantly less in group B (4.8+/-1.4 cm s(-1)) than in group A (7.7+/-1.9 cm s(-1)). However, there was no significant difference between groups A and C (8.3+/-0.8 cm s(-1)). A transmitral E/A >1.0 was observed in 12/147 patients of group A, 10/88 of group B, and 8/8 of group C. The incidence of >or=Sellers' grade II mitral regurgitation was higher in group C than the others. CONCLUSIONS: A paradoxically faster mitral annular velocity during early diastole is found in patients having left ventricular dysfunction with moderate to severe mitral regurgitation and considerably high left ventricular filling pressure. Attention should be paid to an interpretation of mitral annular velocity during early diastole regarding left ventricular early diastolic performance in patients having mitral regurgitation with an E/A >1.0 in their transmitral flow.     

A simple Doppler echocardiographic method for estimating severity of aortic regurgitation

Doppler echocardiography is useful for detecting aortic regurgitation (AR). To determine if the presence of retrograde holodiastolic flow in the abdominal aorta can be used to assess the severity of AR, abdominal aortic flow velocity was examined by pulsed Doppler echocardiography in 33 patients with AR and 10 patients without AR confirmed by aortography, and in 15 normal subjects. Among the 33 patients with AR, 15 had mitral regurgitation, 11 had mitral stenosis, 8 had aortic stenosis, 5 had prosthetic mitral valves, 4 had prosthetic aortic valves and 2 had aorticopulmonary shunts. No retrograde holodiastolic flow was found in the abdominal aorta of 15 normal subjects or 10 patients without AR. Of the 22 patients with 1+ or 2+ AR independently determined by injection of iodinated contrast into the aortic root, 21 did not have retrograde holodiastolic abdominal aortic flow, whereas all 11 patients with 3+ or 4+ AR had retrograde holodiastolic flow in the abdominal aorta. One patient with 1+ AR and a left-to-right aorticopulmonary shunt had retrograde holodiastolic flow in the abdominal aorta. The finding of holodiastolic retrograde flow in the abdominal aorta is useful for distinguishing patients with severe AR from those with mild or absent AR. Moreover, the method is easy to perform and results appear to be independent of the presence of other cardiac diseases except significant aorticopulmonary shunt.     

Forward stroke volume calculated from aortic valve echograms in normal subjects and patients with mitral regurgitation secondary to left ventricular dysfunction

A clinically applicable method was developed for calculating aortic valve stroke volume using the echocardiographically recorded initial and late aortic cusp separation, ejection time and amplitude of posterior aortic root motion during ejection. The formula was tested prospectively in 55 patients for whom 65 Fick [n = 26]or thermodilution [n = 39]cardiac output determinations were performed simultaneously with echocardiography. Aortic valve echograms were recorded in all patients and mitral valve echograms were also recorded in 48 of the 55 patients. Twenty patients had nonrheumatic mitral regurgitation. For the 65 studies, linear correlation (r) was excellent between the aortic valve method and Fick or thermodilution method for stroke volume (r = 0.96, standard error of the estimate [SEE]± 6 cc) and for cardiac output (r = 0.92, SEE ± 0.44 liters). Differences between cardiac output values obtained from aortic valve echograms and either Fick or thermodilution techniques ranged from −1.4 to +1.5 liters/min and were normally distributed. Ninety percent of the computed aortic valve data was within 15 percent of the Fick or thermodilution data.

Aortic valve stroke volume correlated well (r = 0.93) with stroke volume derived from mitral valve echograms in the patients without mitral regurgitation but did not correlate well (r = 0.78) in the patients with mitral regurgitation. Mitral valve stroke volume exceeded aortic valve stroke volume by more than 20 percent in 19 of the 20 patients with mitral regurgitation compared with 1 of 28 patients without mitral regurgitation. The presence or absence of ventricular dyssynergy did not alter statistical findings. Data from this study show that (1) aortic valve echograms can be used clinically to measure forward stroke volume, and (2) the difference between mitral valve and aortic valve volume should be a measure of mitral regurgitant flow.     

Quantification of regurgitant fraction in mitral regurgitation by cardiovascular magnetic resonance: comparison of techniques

BACKGROUND AND AIM OF THE STUDY: Cardiovascular magnetic resonance (CMR) assessment of mitral regurgitant volume from the subtraction of the right ventricular stroke volume (RVSV) from left ventricular stroke volume (LVSV) has commonly been performed using volumetric techniques. This is sensitive to errors in RVSV visualization and regurgitation of other heart valves, and therefore subtracting aortic flow volume from LVSV may be preferable. The study aim was to compare both techniques in a single CMR examination. METHODS: Twenty-eight patients with isolated mitral regurgitation underwent left ventricular (LV) and right ventricular (RV) volumetry and aortic flow volume measurements. Mitral regurgitant fraction (RF) was calculated as either RF(VOL) = [LVSV - RVSV] or RF(FLOW) = [LVSV - aortic flow volume], both expressed as a fraction of LVSV. The agreement of the measurements was assessed as a measure of robustness in clinical practice. RESULTS: There was good agreement between aortic and pulmonary flow (mean +/- SD difference -0.8 +/- 8.1 ml), and aortic flow volume and RVSV by volumetry (mean difference -2.6 +/- 11.8 ml). Intra- and interobserver variability (SD) of aortic flow volume (+/-6.6 ml and +/-5.3 ml) was superior to that of the RVSV (+/-8.5 ml and +/-12 ml). The intra- and inter-observer variability (SD) of RF(FLOW) was lower (+/-4.8% and +/-7.7%) than by RF(VOL) (+/-6.7% and +/-8.8%). CONCLUSION: The RF(FLOW) technique maximized intra- and inter-observer agreement, and is the optimal CMR technique to quantify mitral regurgitation. RF(FLOW) also has the advantage of allowing correction for aortic regurgitation when it is present, and is potentially independent of the effects of tricuspid and pulmonary regurgitation.     

Assessment of aortic insufficiency by transcutaneous Doppler ultrasound.

Using a 2.2 MHZ directional Doppler ultrasound unit, the instantaneous peak aortic velocity pattern was recorded transcutaneously in 15 normal persons and 15 patients with aortic insufficiency. The transducer was positioned in the suprasternal notch and aimed posteriorly to cross the descending aortic arch at an angle approximately parallel to blood flow. The electrocardiogram, phonocardiogram, and carotid pulse tracings were recorded simultaneously. In patients with aortic insufficiency there was significant diastolic flow that was not present in normal persons. The planimetered area under the systolic and diastolic velocity tracings represents the distance forward and backward that the stroke volume moves. The ratio was used to approximate the percent regurgitation, which ranged from 9% to 68%. From left ventricular angiograms in the patients with aortic regurgitation single plane ventricular volume measurements were used to calculate ventricular output and when compared with the Fick cardiac output gave an estimate of true percent regurgitation. A strong correlation was obtained with the Doppler estimate (r=0.91), confirming that this simple ultrasound technique can accurately assess the degree of aortic insufficiency.     

End diastolic flow velocity just beneath the aortic isthmus assessed by pulsed Doppler echocardiography: a new predictor of the aortic regurgitant fraction.

End diastolic flow velocity just beneath the aortic isthmus was measured within 72 hours of cardiac catheterisation by pulsed Doppler echocardiography in 30 controls and 61 patients with aortic regurgitation. The end diastolic flow velocity was determined at the peak R wave on a simultaneously recorded electrocardiogram. In all controls there was no reverse flow at the end diastole beneath the aortic isthmus. In patients with aortic regurgitation the end diastolic flow velocity correlated well with the angiographic grade of regurgitation (r = 0.81) and regurgitant fraction (r = 0.82). The mean (SD) values were 6.3 (5.2), 12.2 (4.3), 22.1 (5.7), and 34.3 (9.3) cm/s for patients with regurgitant fraction of less than 20%, between 20% and 40%, between 41% and 60%, and greater than 60%, respectively. An end diastolic flow velocity of greater than 18 cm/s predicted a regurgitant fraction of greater than or equal to 40% with a sensitivity of 88.5% and a specificity of 96%. The study suggests that the pulsed Doppler derived end diastolic flow velocity is a useful index in the routine non-invasive assessment of the severity of aortic regurgitation.     

Measurement of aortic and mitral regurgitation by gated cardiac blood pool scans.

A simple, noninvasive radionuclide technique which measures the severity of valvular regurgitation has been developed. The technique compares right and left ventricular stroke volume indices (change in counts between diastole and systole over the left and right ventricles) from 45 degrees LAO gated cardiac blood pool scans. In 14 control subjects, the left-to-right ventricular stroke index ratio was near unity (1.15 +/- 0.15 [SD]). In 26 patients with mitral and/or aortic regurgitation it was larger (range 1.36--5.30, mean 2.44). Comparison between the stroke index ratio and qualitative angiographic estimates of regurgitation revealed good agreement (F = 45.5, p less than 0.001). Gated cardiac blood pool scans permit noninvasive assessment of the severity of valvular regurgitation.     

Noninvasive evaluation of the magnitude of aortic and mitral regurgitation by means of Doppler two-dimensional echocardiography

Using transmitral flow velocity and left ventricular ejection flow velocity, we measured left ventricular inflow volume (LVIV) and left ventricular outflow volume (LVOV) by pulsed Doppler echocardiography in 73 patients who had mitral valve regurgitation (MR), aortic valve regurgitation (AR), or no valvular regurgitation. Doppler-determined regurgitant volume (DOPRV), Doppler-determined regurgitant fraction (DOPRF), total stoke volume, and forward stroke volume were calculated to compare the severity assessed by angiographic scoring and the regurgitant fraction determined by radionuclide angiography (RIRF). In 17 patients with MR, LVIV (84.4 +/- 20.4 ml) was significantly greater (p less than 0.01) than LVOV (52.5 +/- 15.7 ml). LVOV, which is equivalent to forward stroke volume, was lower in patients with MR (52.2 +/- 15.7 ml) than in normal subjects (67.0 +/- 15.7 ml). In 15 patients with AR, LVOV (121.7 +/- 61.1 ml) was significantly greater (p less than 0.01) than LVIV (75.1 +/- 28.1 ml) and LVOV, which is equivalent to total stroke volume, was greater in patients with AR (121.7 +/- 61.1 ml) than in normal subjects (64.0 +/- 14.4 ml). DOPRF correlated with RIRF (r = 0.79, p less than 0.01, n = 11). DOPRV (mild: 10.5 +/- 8.5 ml; moderate: 28.8 +/- 13.6 ml; severe: 74.5 +/- 36.7 ml) and DOPRF (mild: 13.7% +/- 11.5%; moderate: 33.1% +/- 14.2%; severe: 52.6% +/- 15.3%) increased markedly with the severity of regurgitation as assessed by cineangiography. In AR, total stroke volume influenced both forward stroke volume and regurgitant volume, and in MR, regurgitant volume influenced both total stroke volume and forward stroke volume. Total stroke volume in AR and regurgitant volume in MR may play a key role in valvular regurgitation.     

Quantitative determination of aortic regurgitant volumes in dogs by ultrafast computed tomography

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)     

Quantitation of antegrade and retrograde blood flow in the human aorta by magnetic resonance velocity mapping

Magnetic resonance velocity mapping was used in 24 normal subjects to study two-dimensional velocity profiles in the proximal and mid-ascending aorta, and to quantify both forward and reverse flow. The aortic flow measurements were validated by comparison with left ventricular stroke volume in all subjects and by comparison with pulmonary flow measurements in 12. Agreement was good with standard errors of the estimate of 7.8 and 7.1 ml, and correlation coefficients of 0.93 and 0.95, respectively. Systolic velocity maps were similar in the proximal aorta and the mid-ascending aorta, with maximum early systolic flow along the left posterior wall. Toward the end of systole and throughout diastole, a channel of reverse flow developed in the same region in the mid-ascending aorta, but in the proximal aorta it split to enter the sinuses of Valsalva, predominantly the left and the right coronary sinuses. Mean percentage ratio of retrograde-to-antegrade flow was 6.3%, with the majority of retrograde flow occurring in early diastole. The findings suggest that the retrograde flow is related to coronary artery flow and it is possible that aortic disease, which is known to influence aortic flow patterns, may also influence coronary flow.     

Aortic regurgitant flow by color Doppler measurement of the local velocity 7 mm above the leak orifice--Part 2: Comparison with cardiac catheterization

AIMS: An in vitro study of the flow convergence region in aortic regurgitation has shown that regurgitant flow rate can be derived from the local velocity V(7 mm) at 7 mm distance above the leak orifice. This clinical study was performed to test this method in patients. METHODS AND RESULTS: In 67 patients with aortic regurgitation, the flow convergence region was imaged by color Doppler. By analogy with the afore mentioned in vitro study, velocity profiles of the acceleration across the flow convergence region were read from the color maps. The profiles were fitted by using a multiplicative regression model. The V(7 mm) was read from the regression curve, and instantaneous regurgitant flow Q was derived from the V(7 mm) with the equation developed in vitro (Q = V(7 mm).cm2/0.28). Q showed a close association with the angiographic grade. Q-derived regurgitant stroke volume correlated significantly with invasive measurements by the angio-Fick method (r = 0.897, SEE = 19.9 ml, y = 0.88x + 5.9 ml). CONCLUSIONS: Within the color Doppler flow convergence region of aortic regurgitation, the local velocity at 7 mm distance to the leak reflects regurgitant flow rate.