Assessment and follow-up of patients with aortic regurgitation by an updated Doppler echocardiographic measurement of the regurgitant fraction in the aortic arch

Ultrasound Imaging of the Abdominal Aorta: A Comprehensive Review

Ultrasound is the imaging modality of choice for the initial evaluation of disorders that involve the abdominal aorta (AA). The diagnostic value of ultrasound resides in its ability to allow assessment of the anatomy and structure of the AA using two- dimensional, three-dimensional, and contrast-enhanced imaging. Moreover, ultrasound permits evaluation of the physiologic and hemodynamic consequences of abnormalities through Doppler interrogation of blood flow, thus enabling the identification and quantification of disorders within the AA and beyond its boundaries. The approach to ultrasound imaging of the AA varies, depending on the purpose of the study and whether it is performed in a radiology or vascular laboratory or in an echocardiography laboratory. The aim of this review is to demonstrate the usefulness of ultrasound imaging for the detection and evaluation of disorders that involve the AA, detail the abnormalities that are detected or further assessed, and outline its value for echocardiographers, sonographers, and radiologists.

Grading of aortic regurgitation by cardiovascular magnetic resonance and pulsed Doppler of the left subclavian artery: harmonizing grading scales between imaging modalities

Transthoracic echocardiography (TTE) and cardiac magnetic resonance (CMR) are current standard for assessing aortic regurgitation (AR). Regurgitant fraction (RF) can also be estimated by Doppler examination of the left subclavian artery (LSA-Doppler). However, a comparison of AR grading scales using these methods and a TTE multiparametric approach as reference is lacking. We evaluated the severity of AR in 73 patients (58 ± 15 years; 57 men), with a wide spectrum of AR of the native valve. Using a recommended TTE multiparametric approach the AR was divided in none/trace (n = 12), mild (n = 23), moderate (n = 12), and severe (n = 26). RF was evaluated by LSA-Doppler (ratio between diastolic and systolic velocity–time integrals) and by CMR phase-contrast imaging (performed in the aorta 1 cm above the aortic valve); the grading scales were then calculated. There were a good correlation between all methods, but mean RF values were greater with TTE compared with LSA-Doppler and CMR (39 ± 16% vs. 35 ± 18% vs. 32 ± 20%, respectively; p < 0.037). Mean differences in RF values between methods were significant in the groups with mild and moderate AR. Grading scales that best defined the TTE derived AR severity using CMR were: mild, < 21%; moderate, 22 to 41%; and severe, > 42%; and using LSA-Doppler: mild, < 29%; moderate, 30 to 44%; and severe, > 45%. RF values for AR grading using TTE, LSA-Doppler and CMR correlate well but differ in groups with mild and moderate AR when using a recognized multiparametric echocardiographic approach. Clinical prospective studies should validate these proposed modality adjusted grading scales.

Pulsed-Wave Doppler Recordings in the Proximal Descending Aorta in Patients with Chronic Aortic Regurgitation: Insights from Cardiovascular Magnetic Resonance

BACKGROUND

The pulsed-wave Doppler recording in the descending aorta (PWD_DAO) is one of the parameters used in grading aortic regurgitation (AR) severity. The aim of the present study was to investigate the assessment of chronic AR by PWD_DAO with insights from cardiovascular magnetic resonance (CMR).

METHODS

This prospective study comprised 40 patients investigated with echocardiography and CMR within 4 hours either prior to valve surgery (n = 23) or as part of their follow-up (n = 17) due to moderate or severe AR. End-diastolic flow velocity (EDFV) and the diastolic velocity time integral (dVTI) were measured. The appearance of diastolic forward flow (DFF) was noted. Phase-contrast flow rate curves were obtained in the DAO.

RESULTS

Twenty-five patients had severe and eight had moderate AR by echocardiography (seven were indeterminate). The EDFV was below the recommended threshold (>20 cm/sec) in 13 patients (52%) with severe AR. Lowering the EDFV threshold (>13 cm/sec) and with a dVTI threshold >13 cm showed negative likelihood ratios of 0.27 and 0.09, respectively. Detection of DFF with PWD_DAO identified a nonuniform velocity profile by CMR with positive and negative likelihood ratios of 7.0 and 0.19, respectively. The relation between EDFV and DAO regurgitant volume (DAO-RVol_CMR) was strong in patients without (R = 0.88) and weak in patients with DFF (R = 0.49). The DAO-RVol_CMR as a percent of the total RVol_CMR decreased with increasing ascending aorta (AAO) size and increased with increasing AR severity.

CONCLUSIONS

Our findings suggest that PWD_DAO provides semiquantitative parameters useful to assess chronic AR severity. The limitations are related to nonuniform velocity contour and variable degree of lower body contribution, which depends on AR severity but also on the AAO size.

Holodiastolic Flow Reversal at the Descending Aorta on Cardiac Magnetic Resonance is Neither Sensitive Nor Specific for Significant Aortic Regurgitation in Patients with Congenital Heart Disease

Holodiastolic flow reversal in the descending aorta on echocardiogram suggests significant aortic regurgitation. The study aim was to determine whether the presence of holodiastolic flow reversal on cardiac magnetic resonance imaging (MRI) correlates with aortic valve regurgitant fraction. We retrospectively reviewed 166 cardiac MRIs (64 % male, age 14.1 ± 9.5 years) from January 2011 to May 2012 where velocity mapping was acquired at both the aortic valve and the descending aorta at the level of the diaphragm. Descending aorta velocity maps were checked for baseline offset using a static reference region. Holodiastolic flow reversal was defined as flow reversal throughout diastole both before and after baseline correction. Significant aortic regurgitation was defined as regurgitant fraction >10 %. Aortic valve regurgitant fraction was <10 % in 144 patients (Group A), 10-20 % inclusive in 7 patients (Group B), and >20 % in 15 patients (Group C). Though the aortic valve regurgitant fraction was significantly higher for patients with holodiastolic flow reversal versus those without (8.5 ± 14.2 vs. 3.8 ± 6.6 %, p = 0.02), holodiastolic flow reversal was present in 32 Group A patients (22 %). In comparison, 4 Group B patients (57 %) and 7 Group C patients (47 %) had holodiastolic flow reversal. The sensitivity (Groups B and C) was 0.5, and the specificity (Group A) was 0.78. Holodiastolic flow reversal in the descending aorta on cardiac MRI was neither sensitive nor specific for predicting significant aortic regurgitation in this study population. Holodiastolic flow reversal in the absence of significant aortic regurgitation may be a relatively common finding in patients with congenital heart disease.

Natural progression of low-gradient severe aortic stenosis with preserved ejection fraction

Because the natural progression of low-gradient aortic stenosis (LGAS) has not been well defined, we performed a retrospective study of 116 consecutive patients with aortic stenosis who had undergone follow-up echocardiography at a median interval of 698 days (range, 371-1,020 d). All patients had preserved left ventricular ejection fraction (>0.50) during and after follow-up. At baseline, patients were classified by aortic valve area (AVA) as having mild stenosis (≥1.5 cm(2)), moderate stenosis (≥1 to <1.5 cm(2)), or severe stenosis (<1 cm(2)). Severe aortic stenosis was further classified by mean gradient (LGAS, mean <40 mmHg; high-gradient aortic stenosis [HGAS], mean ≥40 mmHg). We compared baseline and follow-up values among 4 groups: patients with mild stenosis, moderate stenosis, LGAS, and HGAS. At baseline, 30 patients had mild stenosis, 54 had moderate stenosis, 24 had LGAS, and 8 had HGAS. Compared with the moderate group, the LGAS group had lower AVA but similar mean gradient. Yet the actuarial curves for progressing to HGAS were significantly different: 25% of patients in LGAS reached HGAS status significantly earlier than did 25% of patients in the moderate-AS group (713 vs 881 d; P=0.035). Because LGAS has a high propensity to progress to HGAS, we propose that low-gradient aortic stenosis patients be closely monitored as a distinct subgroup that warrants more frequent echocardiographic follow-up.

Postsurgical hemodynamics of the aortic valve bypass operation evaluated with phase contrast magnetic resonance

PURPOSE

To characterize the postsurgical hemodynamics in aortic valve bypass (AVB) patients, and to determine the relationship between presurgical native aortic valve pressure gradient and postsurgical hemodynamics.

MATERIALS AND METHODS

Twenty patients scheduled for AVB surgery underwent presurgical transthoracic Doppler echocardiography to assess the degree of aortic stenosis and postsurgical cardiac magnetic resonance imaging (MRI) to acquire phase contrast magnetic resonance (PCMR) flow values along the ascending and descending aorta, and in the conduit. Net flow values were calculated from the PCMR images and compared to presurgical aortic valve pressure gradient measurements.

RESULTS

PCMR showed that: 1) The blood flow split between the aorta and the conduit was 35%:65% of cardiac output and 2) 60% of patients had net retrograde blood flow in the superior thoracic aorta over the cardiac cycle. Patients with presurgical pressure gradient (ΔP) > 45 mmHg had significantly less blood flow out of the native aorta than patients with ΔP < 45 mmHg, and had significantly more retrograde flow in the superior thoracic aorta postsurgery.

CONCLUSION

In patients undergoing AVB, presurgical aortic valve pressure gradient is associated with the volume of blood flow out the aorta and the direction of blood flow in the superior thoracic aorta after conduit addition as measured by PCMR.

Pulse-wave Doppler interrogation of the abdominal aorta: a window to the left heart and vasculature

Systematic imaging of the abdominal aorta during transthoracic echocardiography is advocated as a useful screening tool for aortic aneurysms. The addition of pulse Doppler interrogation to the two-dimensional imaging can be highly valuable and provides incremental hemodynamic information regarding a wide spectrum of diseases that involve the left heart, aorta, and vasculature. In this manuscript, we review the usefulness of pulse Doppler recording of the abdominal aorta and provide case examples of its value in various disease states.

Effect of bisphosphonates on the progression of degenerative aortic stenosis

Bisphosphonates appear to regulate mineralization in both bone and vasculature. Degenerative aortic stenosis (AS) is thought to be due to vascular calcification. We studied the effect of bisphosphonates on the progression of degenerative AS. A retrospective study was performed on patients >70 years, who had transthoracic echocardiograms (TTE) >1 year apart and an initial aortic valve area (AVA) of 0.6-2.0 cm². Patients were excluded if they had an ejection fraction <40%, other significant valvular or congenital heart disease, end-stage renal disease or heart transplant. The cohort was divided depending on the use of bisphosphonates. Data were obtained by review of the TTE reports. AVA, peak and mean aortic valve gradient (AVG), and the change between the studies were calculated. Of 4,270 patients screened for AS, 76 patients fit study criteria with 8 in the bisphosphonate group and 68 in the nonbisphosphonate group. The period between the TTEs was 23 ± 5 months in both the groups. AVA in the nonbisphosphonate group worsened by 0.2 cm² and in the bisphosphonate group it improved by 0.1 cm² (P = 0.001 vs. nonbisphosphonate). The changes in peak and mean AVG between groups and compared to baseline were not significant. Bisphosphonates show promise for slowing the progression of degenerative AS.

Quantification of chronic aortic regurgitation by vector flow mapping: a novel echocardiographic method

AIMS

Quantification of aortic regurgitation (AR) using echocardiography is challenging. A newly established echocardiographic method, vector flow mapping (VFM), can directly measure blood flow volume (FV) regardless of rheological characteristics. We intended to assess the accuracy of VFM in the quantification of chronic AR.

METHODS AND RESULTS

Twenty-one patients with chronic AR, along with 21 healthy volunteers selected as controls, underwent conventional echocardiography and estimation of aortic blood flow using quantitative Doppler and VFM. The regurgitation ratio (RegR), derived as the quotient of backward and forward aortic FV in the ascending aorta measured by VFM, increased with AR severity: 1.1 +/- 1.5% (normal), 11.4 +/- 3.8% (mild AR), 31.2 +/- 8.0% (moderate AR), and 59.3 +/- 4.7% (severe AR). In a linear regression model, RegR closely correlated with the VC width (r = 0.932) and regurgitation fraction and effective regurgitant orifice measured by the quantitative Doppler method (r = 0.929 and 0.891, respectively). The intra- and interobserver variability of RegR was 4.2 and 6.7%, respectively. There was no difference between RegR measured in the apical five-chamber view and in that in apical three-chamber view using the paired t-test (P = 0.751).

CONCLUSION

RegR measured by VFM, a new Doppler method allowing quantitative analysis of FV in spite of the presence of turbulent flow, is a highly reproducible parameter with good accuracy for AR quantification.

A practical approach to the quantification of valvular regurgitation

This article reviews the methods of determining the severity of mitral and aortic regurgitation, primarily the quantitation using Doppler echocardiography. The Doppler methods, including spatial mapping, proximal flow convergence, vena contracta, continuous-wave Doppler density, and upstream or downstream effects are explained. Various practical pitfalls and performance issues that impact the reliability of these techniques are discussed.

Feasibility of Valve Repair for Regurgitant Bicuspid Aortic Valves—An Echocardiographic Study

BACKGROUND

There is increasing interest in the role of valve repair for patients with isolated severe aortic regurgitation. Those with bicuspid aortic valves are suggested as most suitable for repair. Morphologic features of these valves that suggest feasibility of repair are not well defined.

METHODS

Perioperative echocardiograms on 132 consecutive patients (mean age 42 +/- 12 years; 94% male), with bicuspid valves and isolated aortic regurgitation undergoing surgery at our institution were reviewed. Seventy-five patients (57%) underwent successful valve repair. Repair was attempted but unsuccessful for another 8 patients (6 intraoperatively and 2 before discharge).

RESULTS

Cusp prolapse was the most common primary mechanism of regurgitation (88 patients [67%]), with 81 patients having primarily eccentrically directed regurgitation. Echocardiographic examination of 72 (55%) had evidence of cusp thickening with 40 (30%) having cusp calcification. By multivariate analysis, an eccentric regurgitant jet direction (odds ratio = 14.3; 95% confidence interval [CI] = 3.4 to 59.6), lack of cusp thickening (odds ratio = 5.9 [1.7 to 20]), lack of cusp calcification (odds ratio = 4.2; [1.1 to 16.7]) and the absence of commissural thickening (odds ratio = 4.8 [1.3 to 16.7]) were independently associated with a greater likelihood of successful valve repair. Greater cusp thickening was the only factor associated with attempted but failed repair.

CONCLUSIONS

Successful repair of regurgitant bicuspid aortic valves was more feasible for those patients with eccentric regurgitant jets, those without cusp or commissural thickening or cusp calcification. Recognition of these features may enhance patient selection and improve procedural outcomes with aortic valve repair.

Aortic regurgitation: quantitative methods by echocardiography

Quantification of aortic regurgitation (AR) is a common and difficult clinical problem. The severity of regurgitation has traditionally been estimated with the use of contrast aortography, which is impractical as a screening tool or for serial examinations. In the past two decades, Doppler echocardiography has emerged as an important tool in the quantification of AR. Pulsed Doppler mapping of the depth of the regurgitant jet into the left ventricle was one of the initial echocardiographic methods used for this purpose. The slope and pressure (or velocity) half-time of continuous-wave Doppler profiles of regurgitant jets are also useful. These Doppler techniques may be used to determine the regurgitant volume or regurgitant fraction in patients with AR. The use of color Doppler to measure the height (or cross-sectional area) of the regurgitant jet relative to the height (cross-sectional area) of the left ventricular outflow tract is both sensitive and specific in the quantification of AR. More recently, the continuity principle has been used to determine the effective aortic regurgitant orifice area, which increases as AR becomes more severe. Although this is a promising tool, calculation of this value is not yet common practice in most echocardiography laboratories. Although no single echocardiographic technique is without limitations, all have some validity, and it is reasonable to use a combination of them to obtain a composite estimate of the severity of AR.

Influence of left ventricular relaxation on the pressure half time of aortic regurgitation

BACKGROUND

The severity of aortic regurgitation can be estimated using pressure half time (PHT) of the aortic regurgitation flow velocity, but the correlation between regurgitant fraction and PHT is weak.

AIM

To test the hypothesis that the association between PHT and regurgitant fraction is substantially influenced by left ventricular relaxation.

METHODS

In 63 patients with aortic regurgitation, subdivided into a group without (n = 22) and a group with (n = 41) left ventricular hypertrophy, regurgitant fraction was calculated using the difference between right and left ventricular cardiac outputs. Left ventricular relaxation was assessed using the early to late diastolic Doppler tissue velocity ratio of the mitral annulus (E/ADTI), the E/A ratio of mitral inflow (E/AM), and the E deceleration time (E-DT). Left ventricular hypertrophy was assessed using the M mode derived left ventricular mass index.

RESULTS

The overall correlation between regurgitant fraction and PHT was weak (r = 0.36, p < 0.005). In patients without left ventricular hypertrophy, there was a significant correlation between regurgitant fraction and PHT (r = 0.62, p < 0.005), but not in patients with left ventricular hypertrophy. In patients with a left ventricular relaxation abnormality (defined as E/ADTI< 1, E/AM< age corrected lower limit, E-DT >/= 220 ms), no associations between regurgitant fraction and PHT were found, whereas in patients without left ventricular relaxation abnormalities, the regurgitant fraction to PHT relations were significant (normal E/AM: r = 0.57, p = 0.02; E-DT< 220 ms: r = 0.50, p < 0.001; E/ADTI < 1: r = 0.57, p = 0.02).

CONCLUSIONS

Only normal left ventricular relaxation allows a significant decay of PHT with increasing aortic regurgitation severity. In abnormal relaxation, which is usually present in left ventricular hypertrophy, wide variation in prolonged backward left ventricular filling may cause dissociation between the regurgitant fraction and PHT. Thus the PHT method should only be used in the absence of left ventricular relaxation abnormalities.

An integrated approach to the quantification of aortic regurgitation by Doppler echocardiography

BACKGROUND

Although different Doppler methods have been proposed for the quantification of aortic regurgitation, no study has prospectively compared these methods with each other and their correlation with angiography. The aim of this study was to prospectively analyze the usefulness of different Doppler echocardiography parameters by testing all such parameters in each patient.

METHODS

Fifty-one patients with aortic regurgitation underwent 2-dimensional and Doppler echocardiographic studies and catheterization. The following Doppler indexes were analyzed and compared with aortography. Color Doppler: (1) jet color height/left ventricular outflow tract height in parasternal long-axis view, and (2) jet color area/left ventricular outflow tract area in short-axis view. Continuous Doppler: (3) regurgitant flow pressure half-time, (4) regurgitant flow time velocity integral (in centimeters), and (5) regurgitant flow time velocity integral (in centimeters)/diastolic period (in milliseconds). Pulsed Doppler in thoracic and abdominal aorta: (6) time velocity integral of diastolic reverse flow (in centimeters), (7) time velocity integral of systolic anterograde flow/integral of diastolic reverse flow, (8) (time velocity integral of diastolic reverse flow/diastolic period) x 100, and (9) diastolic reverse flow duration/diastolic period (as a percentage). We compared these parameters with severity of regurgitation measured by angiography and classified as mild, moderate, or severe.

RESULTS

The most useful parameters were (1) jet color height/left ventricular outflow tract height (correctly classified 42 of 49 patients), (2) (time velocity integral of diastolic reverse flow/diastolic period) x 100 in the thoracic aorta (correctly classified 41 of 46 patients), and (3) (time velocity integral of diastolic reverse flow/diastolic period) x 100 in the abdominal aorta (correctly classified 42 of 49 patients). Sequential integration of these 3 parameters correctly classified 96% of patients (44 of 46 patients) and was achieved in 90% of cases.

CONCLUSION

An integrated combination of several Doppler parameters can quickly and accurately classify the degree of aortic regurgitation as determined by angiography.

Assessment of valvular regurgitation with Doppler echocardiography

Echocardiography is routinely performed for the evaluation of valvular regurgitation. Different applications of Doppler echocardiography have been successfully applied to detect and quantify valvular regurgitation. Recent advances in color Doppler made possible the study of the dynamic behavior of the regurgitant orifice and, along with continuous wave Doppler, can provide data on the regurgitant volume and fraction. Doppler echocardiography can also be used to follow serial changes in these hemodynamically important parameters after medical or surgical therapy.

Evaluation of prosthetic valve function and associated complications

Significant advances in imaging modalities have occurred to evaluate prosthetic valve function and associated complications. These developments involve predominantly the introduction of Doppler technology for the non-invasive determination of gradients and valve areas and TEE for an improved assessment of valve structure, function, and associated complications. The current role of cinefluoroscopy is mostly to complement TEE in the evaluation of motion of mechanical prosthetic valves in the aortic position. Cardiac catheterization is now rarely needed to assess valve function. Diagnosis of prosthetic valve obstruction can be performed in the majority of cases with transthoracic Doppler echocardiography. Differentiation of valve obstruction from normal valve function in small valves with high flow conditions, however, may be difficult. Because of this and the variability in normal valves among different prostheses, knowledge of the type and size of the implanted valve is essential. Patients and ultrasound laboratories are encouraged to seek and provide this information on a routine basis. Although transthoracic echocardiography is the main diagnostic modality for the serial evaluation of prosthetic valve function, it is important to recognize its limitations in assessing prosthetic mitral regurgitation and evaluating structural abnormalities of prosthetic valves. These are the situations in which TEE has the most impact. A summary of general indications of TEE in prosthetic valves is provided in Table 6. Finally, a baseline transthoracic Doppler study is essential in the overall follow-up and serial evaluation of valve function. For future comparisons, the best indices of valve functions are those obtained for patients as their own control, from a baseline Doppler echocardiographic study performed early after the operation.

Beneficial effects of 1-year captopril therapy in children with chronic aortic regurgitation who have no symptoms

OBJECTIVE

This prospective study was performed to assess the effects of 1 year of angiotensin-converting enzyme inhibition with captopril in 20 children (mean age 14.3+/-2.3 years) with asymptomatic chronic aortic regurgitation.

METHODS AND RESULTS

At 12 months patients receiving captopril had a significant reduction in left ventricular end-diastolic and end-systolic dimensions (57+/-9.3 vs 51+/-9.5 mm, p < 0.001; 35.4+/-6.1 vs 32+/-6.8 mm, p < 0.001), end-diastolic and end-systolic volume indexes (111+/-36 vs 94+/-29 ml/m2, p < 0.001; 35+/-13 vs 30+/-12 ml/m2, p < 0.001, respectively), and mass index (138+/-37 vs 109+/-32 gm/m2, p < 0.0001) determined by two-dimensional echocardiography. Meridian (p < 0.01) and circumferential (p < 0.0001) wall stresses also decreased significantly with therapy. Significant reduction (27.8%, p < 0.0001) was achieved in regurgitant fraction with captopril.

CONCLUSIONS

These data show that the long-term therapy with angiotensin-converting enzyme inhibitors is able to reverse left ventricular dilation and hypertrophy and suggest that such therapy has the potential to favorably influence the natural history of the disease in children.

Progressive enlargement of the regurgitant orifice in patients with chronic aortic regurgitation

The severity of aortic regurgitation is dependent on the size of the regurgitant orifice, the left ventricular response to volume overload, and the diastolic pressure difference across the aortic valve. The purpose of this study was to test the hypothesis that the aortic regurgitant orifice increases over time in patients with audible chronic aortic regurgitation. To assess serial changes in aortic regurgitant severity by the use of two-dimensional and Doppler echocardiography, 59 patients (29 men and 30 women) with audible chronic aortic regurgitation were prospectively identified and evaluated annually with two-dimensional and Doppler echocardiograms. Patients were followed for a median of 38 months. We measured two separate indicators of the size of the regurgitant orifice: the color Doppler regurgitant jet width and the Doppler-derived regurgitant orifice area. Jet width increased with time (0.5 +/- 0.4 cm at baseline, 0.04 +/- 0.01 cm/year slope, p < 0.001). The regurgitant orifice area also increased (0.12 +/- 0.14 cm2 at baseline, 0.01 +/- 0.01 cm2/year, p = 0.05). Changes in regurgitant orifice area were related to changes in left ventricular end-diastolic dimension (p < 0.001). There were no significant changes in left ventricular chamber dimensions, volumes, and regurgitant volume over time in this cohort. Increases in jet width and orifice area occurred in patients with all degrees of baseline disease severity, with bicuspid or tricuspid leaflet morphology, and with male or female sex. In this prospective study of chronic aortic regurgitation, both jet width and Doppler-derived regurgitant orifice area increased over time. These findings suggest that one factor in the progression of chronic aortic regurgitation is enlargement of the orifice.

Two-dimensional echocardiographic assessment of the progression of aortic root size in 127 patients with chronic aortic regurgitation: role of the supraaortic ridge and relation to the progression of the lesion

Although aortic root dilation has etiologic and prognostic significance in patients with chronic aortic regurgitation (AR), no information is available regarding changes over time in aortic root size in patients with the entire spectrum of AR severity or how such changes relate to progression of the AR or to left ventricular (LV) overload. To analyze this, a total of 127 patients with chronic AR who had more than 6 months of follow-up by two-dimensional and Doppler echocardiography were included in the study (69 men and 58 women; mean age 59.3 +/- 21.2 years [range 14 to 94 years]; 67 cases of mild, 45 moderate, 15 severe, and 21 bicuspid aortic valve disease). The aortic anulus, sinuses of Valsalva, supraaortic ridge, and ascending aorta were measured in the parasternal long-axis view, LV volumes were calculated (biplane Simpson's approach), and the severity of AR was quantified based on proximal jet size and graded according to an algorithm that takes into account major color Doppler criteria. At entry to the study, significant differences between patients with mild, moderate, and severe AR were noted only in supraaortic ridge size (1.46 +/- 0.29 cm/m2 vs 1.63 +/- 0.33 cm/m2 [p < 0.006]; vs 1.67 +/- 0.43 cm/m2 [p < 0.03]). A significant increase in aortic root size at all levels was observed during the follow-up period in all three groups of severity of AR. The rate of change of the supraaortic ridge, the upper support structure of the anulus and cusps, was faster in patients with more severe degrees of AR (p = 0.013); this was not the case at the other aortic levels. No differences were observed in aortic root size or rate of progression between patients with bicuspid or tricuspid aortic valves. Patients were considered "progressive" if they lay on the steepest positive segment of the curve representing the rank order in the rate of aortic root progression. Compared with "nonprogressive" patients, patients who were progressive in supraaortic ridge size (rate >0.12 cm/yr; n = 23) had a faster rate of progression in the degree of regurgitation as assessed by the regurgitant jet area/LV outflow tract area ratio measured in the parasternal short-axis view (0.48 +/- 0.45 vs 0.24 +/- 0.5/yr; p < 0.03) and a foster rate of progression of LV end-diastolic volume (30 +/- 22.8 vs 14.4 +/- 15.6 ml/yr; p < 0.0002) and LV mass (70.8 +/- 74.4 vs 16.8 +/- 19.2 gm/yr; p < 0.0004). In conclusion, there is progressive dilation of the aortic root at all levels, even in patients with mild AR. More rapid progression in aortic root size is associated with more rapid progression of the underlying aortic insufficiency, as well as more rapid increases in LV volume and mass.

Doppler echocardiographic assessment of progression of aortic regurgitation

The rate of progression of the degree of chronic aortic regurgitation (AR) is unknown. Furthermore, although left ventricular (LV) dilation has been studied in patients with severe AR, its rate and determining factors, and specifically, its relation to the degree of regurgitation remain to be established and have not previously been studied for mild and moderate AR. The purpose of this study was to explore the progression of chronic AR by 2-dimensional and Doppler echocardiography, and the relation of LV dilation to the fundamental regurgitant lesion and its progression in patients with a full spectrum of initial AR severity. We studied 127 patients with AR by 2-dimensional and Doppler echocardiography (69 men; 59 +/- 21 years; 67 with mild, 45 with moderate, 15 with severe AR). AR increased in 38 patients (30%) (25% of mild, 44% of moderate, and 50% of moderate to severe lesions; p <0.006). The ratio of proximal AR jet height to LV outflow tract height also increased (30.3 +/- 17.5% vs 35.2 +/- 19.7%; p <0.0001). Initial LV volumes and mass were larger in patients with more severe AR and increased significantly during follow-up (138 +/- 53 to 164 +/- 70 ml; 59 +/- 32 to 71.7 +/- 42 ml; 203 +/- 89 to 241 +/- 114 g; p <0.0001). LV volumes and mass increased faster in patients with more severe AR, and in those in whom the degree of AR progressed more rapidly. Finally, patients with bicuspid aortic valve (n = 21) had a higher prevalence of severe AR than patients with tricuspid aortic valves (52% vs 4%; p <0.001). In conclusion, AR is a progressive disease not only in patients with severe AR but also in those with mild and moderate regurgitation. Patients with more severe AR have larger left ventricles that also dilate more rapidly.

Hemodynamic performance of small aortic valve bioprostheses: is there a difference?

BACKGROUND

There is the potential for left ventricular outflow obstruction when small aortic valve bioprostheses are employed in normal-sized or large adults. It has been hoped that bovine pericardial valves would improve hemodynamic performance in the smaller tissue valve sizes.

METHODS

To determine in vivo hemodynamic performance of heterograft aortic valve prostheses, we analyzed echocardiographic data from patients receiving 21- or 23-mm Carpentier-Edwards pericardial, Medtronic Intact, and Carpentier-Edwards porcine bioprostheses. In addition, data from 19-mm Carpentier-Edwards pericardial valves were included for comparison of hemodynamic performance between valve sizes. Doppler echocardiography was performed in 151 patients within 2 weeks of operation. Left ventricular outflow gradient was derived from continuous Doppler measurements of flow velocity, and effective orifice area was calculated by the continuity equation.

RESULTS

There were statistically significant differences in hemodynamic performance of different sized prostheses for each valve type (effective orifice area, p < 0.01; valvular gradient, p < 0.03). There were, however, no significant differences in effective orifice area or mean gradient for different valve types within each size category.

CONCLUSIONS

The in vivo hemodynamic performance of these three different aortic valve heterograft bioprostheses is similar. Patient-prosthesis mismatch with heterograft prostheses, as demonstrated by the indexed effective orifice area can be avoided by appropriate sizing and use of annular enlarging techniques when necessary.

Aortic flow velocity patterns in chronic aortic regurgitation: implications for Doppler echocardiography

Aortic regurgitation is associated with retrograde diastolic flow in the aorta. Echocardiographic quantitative analysis of the magnitude of the flow reversal is believed to provide an estimate of severity of regurgitant disease despite variations in flow profiles. The purpose of this study was to evaluate the uniformity of flow patterns in the aorta of patients with aortic regurgitation and to investigate the relationship between these profiles and the echocardiographic estimates of flow reversal. Seventeen patients with chronic aortic regurgitation underwent cine-phase magnetic resonance imaging in an axial section through the ascending and descending aorta. The regurgitant fraction in the ascending aorta 4 cm above the aortic valve and the descending aorta were calculated from the velocity maps. These results were compared with data from nine individual sample volumes in the ascending and descending aorta. The magnetic resonance ascending aortic regurgitant fraction was compared with Doppler echocardiographic descending aortic flow velocity patterns. The descending aortic regurgitant fraction correlated only weakly with the ascending aortic regurgitant fraction (descending aortic regurgitant fraction = 0.62% ascending aortic regurgitant fraction + 0.04%; r = 0.75; p < 0.001). Regurgitant proportions in all sample volumes in the descending aorta, but not in the ascending aorta, were significantly related to the ascending aortic regurgitant fraction. The best descending aortic Doppler echocardiographic parameter for predicting ascending aortic regurgitant fraction was the end-diastolic velocity (end-diastolic velocity = 32.2 cm/sec. ascending aortic regurgitant fraction + 1.4 cm/sec; r = 0.94; p < 0.001). Pulsedwave Doppler sampling of descending aortic flow reflects severity of aortic regurgitant disease, in part the result of more uniform blood-velocity profiles in the descending aorta compared with the ascending aorta. The Doppler end-diastolic velocity in the descending aorta is a useful parameter of severity of aortic regurgitation.

A simplified method for determining regurgitant fraction by Doppler echocardiography in patients with aortic regurgitation

OBJECTIVES

This study attempted to develop and validate a simple method for calculating aortic regurgitant fraction by use of pulsed wave Doppler echocardiography.

BACKGROUND

Although several investigators have been able to determine aortic regurgitant fraction by Doppler echocardiography, the methods used require accurate determination of the cross-sectional areas of intracardiac sites at which the volumetric flow is calculated.

METHODS

Our concept was based on a constant relation that exists between the cross-sectional area of the left ventricular outflow tract and the mitral valve annulus in normal subjects. To verify this, we used Doppler echocardiography to measure the flow velocity integral of the left ventricular outflow tract and the mitral annulus in the apical view in 50 normal subjects (32 men, 18 women, mean age 34 years).

RESULTS

Close correlation (r = 0.95) was observed between the flow velocity integral (FVI) of the outflow tract (OT) and that of the mitral annulus (MA): FVIMA/FVIOT = 0.77. Because mitral flow equals aortic flow in normal subjects, the ratio of the cross-sectional area of the mitral annulus to that of the outflow tract was 1/0.77. In patients with aortic regurgitation, the regurgitant fraction (RF) = (Aortic flow-Mitral flow)/Aortic flow = 1-Mitral flow/Aortic flow. Substituting 0.77 for the area component of flow, RF = 1-(1/0.77).(FVIMA/FVIOT). To evaluate the accuracy of this method, we compared the regurgitant fraction derived by Doppler echocardiography with that from catheterization findings in 20 patients with aortic regurgitation (an isolated lesion was found in 14). The regurgitant fraction by catheterization was the difference between total (angiographic) and forward (thermodilution) stroke volumes as a percent of total flow. Good correlation was observed between catheterization and Doppler regurgitant fraction (r = 0.88, SEE 9%, p < 0.01).

CONCLUSIONS

Thus, regurgitant fraction can be estimated from Doppler echocardiography in patients with aortic regurgitation by a method that requires only measurements of the flow velocity integral from the mitral annulus and left ventricular outflow tract.

Doppler ultrasound of the subclavian artery as an aid to quantification of aortic insufficiency

Aortic insufficiency (AI) induces backflow of blood in the arterial system that is most pronounced in the major arteries close to the heart. Assuming that the intensity of the arterial backflow of blood may reflect the severity of AI, the systolic and diastolic flow profiles of the subclavian artery were studied in 40 patients with and 10 patients without AI that was angiographically proved by use of continuous wave Doppler ultrasound (8 MHz transducer, supraclavicular approach). Patients with angiographically determined severe AI (n = 17) had significantly higher diastolic regurgitant flow velocities (V-max) than patients with only mild (n = 9) or moderate (n = 14) degrees of AI (Severe AI = 35.0 +/- 12.0 cm/sec, moderate AI = 16.8 +/- 3.9 cm/sec, mild AI = 7.4 +/- 2.6 cm/sec; p < 0.01) and also showed significantly higher values with regard to the time velocity integral of the regurgitant jet (severe AI = 13.8 +/- 5.6 cm; moderate AI = 5.7 +/- 2.4 cm, mild AI = 1.4 +/- 0.9 cm; p < 0.01). After classification by jacknife discrimination analysis, the Doppler ultrasound grading was compared with a corresponding three-point scale (mild, moderate, severe) from aortic root angiography. A correct estimation of the severity of AI was possible in 44 of 50 patients (88%; overestimation in one, underestimation in five) and in 41 of 50 patients (83%; overestimation in one, underestimation in eight) with regard to V-max and the time velocity integral of the regurgitant jet, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of jet impingement on color Doppler parameters of aortic regurgitation

In vitro studies have demonstrated that the characteristics of a color Doppler jet are influenced by a number of factors including jet eccentricity and jet impingement. To explore the relationship of a jet impingement and aortic regurgitant color Doppler jet parameters, jet area, width, and length were measured from apical echocardiographic views of 84 patients 4 +/- 11 days prior to catheterization and compared to angiographic grade. An impinging color jet contacted the interventricular septum or mitral valve beneath the aortic valve in the imaging plane and a nonimpinging jet did not contact the septum or mitral valve in the imaging plane. As expected, the percentage of patients with impinging jets increased with aortic regurgitation angiographic grade. Neither left ventricular chamber dimensions nor the presence of an aortic prosthesis significantly influenced the color Doppler variables. For a given angiographic grade of aortic regurgitation, impinging jets were associated with larger color Doppler jet widths (P less than 0.05) and areas (P = 0.001) than nonimpinging jets. The color Doppler area and length increased significantly with angiographic grade for nonimpinging jets (P less than 0.05) but not for impinging jets. Impinging jets are associated with larger color Doppler widths and areas than nonimpinging jets for a given grade of aortic regurgitation, possibly because of the effect of jet deflection toward an adjacent wall. Jet impinging should be considered when using color Doppler techniques to evaluate aortic regurgitation.

Semiquantitation of aortic regurgitation by different Doppler echocardiographic techniques and comparison with ultrafast computed tomography

Fourteen patients with chronic aortic regurgitation were studied by several two-dimensional and Doppler echocardiographic methods to determine the severity of aortic regurgitation. Semiquantitation of aortic regurgitation was performed by various color-flow imaging measurements, diastolic half-time of the continuous-wave regurgitation jet, and pulsed-wave velocity curve in the descending aorta. These measurements were compared with regurgitant volume and fraction by ultrafast computed tomography. All Doppler methods demonstrated a significant correlation for severity of aortic regurgitation with regurgitant fraction by ultrafast computed tomographic scanning, but scatter was present with each method. The methods with the closest correlation were at the lowest level of obtainable results. In clinical practice, all Doppler methods must be used to determine the severity of aortic regurgitation.

Calculation of aortic regurgitation orifice area by Doppler echocardiography: an application of the continuity equation

The evaluation of aortic regurgitation by current echocardiographic techniques has been qualitative and load-dependent. The area of the regurgitant orifice, which is theoretically independent of haemodynamic conditions, has not been determined non-invasively. In 20 patients with various degrees of aortic regurgitation, this area was determined by use of the continuity equation applied during diastole. The velocity-time integrals were determined at the supravalvar (VTIs) and regurgitant orifice (VTIj) levels by pulsed and continuous wave Doppler respectively. The cross sectional area at the supravalvar level (As) was also measured by cross sectional echocardiography. The regurgitant orifice is given by: (As x VTIs)/VTIj. Other non-invasive measurements of the aortic regurgitation severity were also recorded: (a) an overall echo score (1-5+) given blindly by two echocardiographers, (b) the maximal proximal jet width by colour Doppler, (c) left ventricular end systolic and end diastolic volumes and left ventricular mass. The regurgitant area ranged from 0.25 to 1.7 cm2 and this area accorded with the overall echo score and the maximal proximal jet width measured by colour Doppler. The aortic regurgitation orifice area can be calculated non-invasively and it may be a quantitative measure of the severity of 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.

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.

Ultrasonic aortic valve decalcification: serial Doppler echocardiographic follow-up

Serial two-dimensional and Doppler echocardiography was performed on 61 patients who had surgical ultrasonic aortic valve decalcification for calcific aortic stenosis. The mean patient age at the time of operation was 77.4 +/- 7.0 years; 93% had moderate to severe preoperative symptomatic limitation. Compared with preoperative studies, Doppler echocardiographic evaluation before hospital discharge revealed a significant reduction in the mean aortic valve pressure gradient (45.3 +/- 16.2 to 14.4 +/- 6.5 mm Hg, p less than 0.0001) and improvement in aortic valve area (0.62 +/- 0.17 to 1.33 +/- 0.33 cm2, p less than 0.0001). There was no initial change in aortic regurgitation grade. Follow-up Doppler echocardiographic evaluation was possible in 43 patients alive at 9.3 +/- 3.9 months. A small but statistically significant trend toward aortic restenosis was found; only one patient had severe restenosis. Severe aortic regurgitation had developed in 26% of patients and moderate aortic regurgitation in 37%. Aortic valve replacement was performed in six patients (14%) with severe symptomatic aortic regurgitation. Significant deficiency in central coaptation as a result of cusp scarification and retraction appeared to be the mechanism of postdecalcification regurgitation. Attempted salvage of the native aortic valve in severe calcific stenosis by ultrasonic decalcification adequately relieves stenosis but leads to an unacceptable incidence of significant aortic regurgitation at follow-up study.

Altered hemodynamic response to isosorbide dinitrate in essential hypertension

Relaxation produced by nitrates on venous, arteriolar, and large arterial vessels is well known but has never been studied in human hypertensive aortas studied in vivo. In this investigation, the effects of acute oral administration of 20 mg of isosorbide dinitrate were evaluated in 12 patients with sustained essential hypertension and nine normotensives of the same age. Noninvasive measurements of systolic, diastolic, and mean arterial pressure, carotid-femoral pulse wave velocity and aortic-arch diastolic diameter using suprasternal echocardiography were determined before and 3 hours after drug administration. In normal subjects, isosorbid dinitrate significantly decreased systolic blood pressure and pulse pressure but did not affect diastolic and mean arterial pressure. In contrast, in hypertensives, the same dosage of isosorbid dinitrate decreased together systolic, diastolic mean, and pulse pressure. In both populations, pulse wave velocity decreased significantly whereas aortic arch diastolic diameter increased markedly. The increase was observed mainly in normal subjects. The study provided evidence that (1) both in normal subjects and hypertensives, isosorbide dinitrate caused an increase in aortic diameter together with an increase in arterial distensibility; and (2) the changes in mean arterial pressure were significant only in hypertensives, indicating that the altered vasodilator response in essential hypertension is not endothelium-mediated.

Pulsatile diameter and elastic modulus of the aortic arch in essential hypertension: a noninvasive study

A noninvasive evaluation of the aortic arch diameter was performed in 16 subjects with sustained essential hypertension and in 15 normal subjects of similar age, gender and body surface area. In all subjects, measurements were obtained of brachial mean arterial pressure and pulse pressure, cardiac mass (judged on echocardiography) and carotid-femoral pulse wave velocity together with ultrasound determinations of aortic arch diastolic and systolic diameter (suprasternal window). For each subject, pulsatile change in aortic diameter, strain and aortic arch elastic modulus were calculated. Compared with normal subjects, the hypertensive subjects showed an increase in aortic arch diameter (diastolic diameter 29.6 +/- 1.0 versus 25.4 +/- 1.0 mm, p less than 0.01), in elastic modulus (1.071 +/- 0.131 versus 0.526 +/- 0.045 10(5) N.m-2, p less than 0.001) and pulse wave velocity (11.8 +/- 0.5 versus 8.9 +/- 0.3 m/s, p less than 0.001). In the study group, a positive correlation was observed between diastolic aortic arch diameter and mean arterial pressure (r = 0.54, p less than 0.01) and between elastic modulus and cardiac mass (r = 0.60, p less than 0.01). Elastic modulus and age were positively correlated (r = 0.73, p less than 0.01) in hypertensive but not in normal subjects (r = 0.08, NS). This study is the first to demonstrate noninvasively that both the aortic arch diameter and the elastic modulus are increased in patients with sustained uncomplicated essential hypertension. These findings suggest that the increase in elastic modulus could influence the development of cardiac hypertrophy, and that both age and blood pressure act independently as factors that alter the arterial wall of subjects with sustained essential hypertension.

Semiquantitative evaluation of aortic regurgitation by Doppler echocardiography: effects of associated mitral stenosis

The accuracy of pulsed and continuous wave (CW) Doppler methods for evaluating aortic regurgitation (AR) was compared in patients with and without mitral stenosis (MS), with aortic root angiography as a gold standard. AR was diagnosed with pulsed Doppler echocardiography, by the detection of broad frequency spectral patterns in the isovolumic relaxation time. If these indications were present, AR was graded by examining the extent of diastolic turbulence in the left ventricular cavity (flow mapping method). With CW Doppler echocardiography, AR was diagnosed by the detection of a peak velocity of greater than 2 m/s; if this velocity was attained, AR was graded by measuring the time from the peak velocity to half the peak velocity (half-time method). The angiographic grade corresponded to that determined by the pulsed and CW Doppler methods in 37 and 37 of 46 patients without MS, respectively. Angiographic grade corresponded to the grade determined by the pulsed and CW Doppler methods in 13 and 17 of the 23 patients with MS, respectively. Eight of 10 discrepancies between pulsed Doppler and angiographic grades were due to overestimation of AR by the flow mapping method, apparently because the transmitral jet produces diastolic turbulence in the left ventricular cavity independent of AR. On the other hand, three of six discrepancies between CW Doppler and angiographic grades were due to the incapability of detecting signals of AR by CW Doppler echocardiography. Thus both the pulsed and the CW Doppler methods are useful to evaluate AR in patients without MS. In patients with MS, however, AR is most accurately diagnosed by the detection of AR signals in the isovolumic relaxation time by pulsed Doppler echocardiography, and the degree of AR is more accurately assessed by the CW Doppler half-time method.