Multiplane transesophageal echocardiographic assessment of mitral regurgitation by Doppler color flow mapping of the vena contracta

Quantification of primary mitral regurgitation by echocardiography: A practical appraisal

The accurate quantification of primary mitral regurgitation (MR) and its consequences on cardiac remodeling is of paramount importance to determine the best timing for surgery in these patients. The recommended echocardiographic grading of primary MR severity relies on an integrated multiparametric approach. It is expected that the large number of echocardiographic parameters collected would offer the possibility to check the measured values regarding their congruence in order to conclude reliably on MR severity. However, the use of multiple parameters to grade MR can result in potential discrepancies between one or more of them. Importantly, many factors beyond MR severity impact the values obtained for these parameters including technical settings, anatomic and hemodynamic considerations, patient's characteristics and echocardiographer' skills. Hence, clinicians involved in valvular diseases should be well aware of the respective strengths and pitfalls of each of MR grading methods by echocardiography. Recent literature highlighted the need for a reappraisal of the severity of primary MR from a hemodynamic perspective. The estimation of MR regurgitation fraction by indirect quantitative methods, whenever possible, should be central when grading the severity of these patients. The assessment of the MR effective regurgitant orifice area by the proximal flow convergence method should be used in a semi-quantitative manner. Furthermore, it is crucial to acknowledge specific clinical situations in MR at risk of misevaluation when grading severity such as late-systolic MR, bi-leaflet prolapse with multiple jets or extensive leak, wall-constrained eccentric jet or in older patients with complex MR mechanism. Finally, it is debatable whether the 4-grades classification of MR severity would be still relevant nowadays, since the indication for mitral valve (MV) surgery is discussed in clinical practice for patients with 3+ and 4+ primary MR based on symptoms, specific markers of adverse outcome and MV repair probability. Primary MR grading should be seen as a continuum integrating both quantification of MR and its consequences, even for patients with presumed “moderate” MR.

Functional mitral regurgitation

PURPOSE OF REVIEW

Functional mitral regurgitation (FMR) is a complex condition in which significant mitral regurgitation coexist with cardiomyopathy and heart failure and carries an increased risk for associated morbidity and mortality. In addition to guideline-directed medical therapy and cardiac resynchronization therapy, percutaneous transcatheter mitral valve repair (TMVr) is a new therapeutic option but requires careful selection of the proper candidates. We describe the different mechanisms of functional mitral regurgitation, review echocardiographic parameters to assess its severity, and discuss recently published relevant studies including TMVr.

RECENT FINDINGS

Two randomized controlled trials assessing the efficacy and safety of TMVr using the MitraClip in patients with heart failure and severe functional mitral regurgitation were published: MITRA-FR (Percutaneous Repair with the MitraClip Device for Severe Functional/Secondary Mitral Regurgitation) and COAPT (Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation). The results of these trials were opposite: although MITRA-FR failed to show clinical benefit, COAPT showed a dramatic clinical and echocardiographic benefit from transcatheter mitral valve repair using the MitraClip device. We discuss these two important trials and how differences in patient enrollment could explain the discrepant results and the manner they may influence future studies and clinical practice.

SUMMARY

Patients with FMR receiving optimal guideline-directed medical therapy and cardiac resynchronization therapy who meet specific clinical and echocardiographic criteria can benefit from transcatheter mitral valve repair.

Multimodality imaging for the quantitative assessment of mitral regurgitation

The natural history of mitral regurgitation (MR) results in significant morbidity and mortality. Innovations in non-invasive imaging have provided new insights into the pathophysiology and quantification of MR, in addition to early detection of left ventricular (LV) dysfunction and prognostic assessment in asymptomatic patients. Transthoracic (TTE) and transesophageal (TOE) echocardiography are the mainstay for diagnosis, assessment and serial surveillance. However, the advance from 2D to 3D imaging leads to improved assessment and characterization of mitral valve (MV) disease. Cardiovascular magnetic resonance (CMR) is increasingly used for MR quantitation and can provide an alternative imaging method if echocardiography is suboptimal or inconclusive. Other techniques such as exercise echocardiography, tissue Doppler imaging and speckle-tracking echocardiography can further offer complementary information on prognosis. This review summarises the current evidence for state-of-the-art cardiovascular imaging for the investigation of MR. Whilst advanced echocardiographic techniques are superior in the evaluation of complex MV anatomy, CMR appears the most accurate technique for the quantification of MR severity. Integration of multimodality imaging for the assessment of MR utilises the advantages of each imaging technique and offers the most comprehensive assessment of MR.

Evolution of Mitral Valve Prolapse: Insights From the Framingham Heart Study

BACKGROUND

Longitudinal studies of mitral valve prolapse (MVP) progression among unselected individuals in the community, including those with nondiagnostic MVP morphologies (NDMs), are lacking.

METHODS AND RESULTS

We measured longitudinal changes in annular diameter, leaflet displacement, thickness, anterior/posterior leaflet projections onto the annulus, coaptation height, and mitral regurgitation jet height in 261 Framingham Offspring participants at examination 5 who had available follow-up imaging 3 to 16 years later. Study participants included MVP (n=63); NDMs, minimal systolic displacement (n=50) and the abnormal anterior coaptation phenotype (n=10, with coaptation height >40% of the annulus similar to posterior MVP); plus 138 healthy referents without MVP or NDMs. At follow-up, individuals with MVP (52% women, 57±11 years) had greater increases of leaflet displacement, thickness, and jet height than referents (all P<0.05). Eleven participants with MVP (17%) had moderate or more severe mitral regurgitation (jet height ≥5 mm) and 5 others (8%) underwent mitral valve repair. Of the individuals with NDM, 8 (80%) participants with abnormal anterior coaptation progressed to posterior MVP; 17 (34%) subjects with minimal systolic displacement were reclassified as either posterior MVP (12) or abnormal anterior coaptation (5). In comparison with the 33 participants with minimal systolic displacement who did not progress, the 17 who progressed had greater leaflet displacement, thickness, coaptation height, and mitral regurgitation jet height (all P<0.05).

CONCLUSIONS

NDM may evolve into MVP, highlighting the clinical significance of mild MVP expression. MVP progresses to significant mitral regurgitation over a period of 3 to 16 years in one-fourth of individuals in the community. Changes in mitral leaflet morphology are associated with both NDM and MVP progression.

Mechanisms of functional mitral regurgitation in ischemic cardiomyopathy determined by transesophageal echocardiography (from the Surgical Treatment for Ischemic Heart Failure Trial)

The mechanisms underlying functional mitral regurgitation (MR) and the relation between mechanism and severity of MR have not been evaluated in a large, multicenter, randomized controlled trial. Transesophageal echocardiography (TEE) was performed in 215 patients at 17 centers in the Surgical Treatment for Ischemic Heart Failure (STICH) trial. Both 2-dimensional (n = 215) and 3-dimensional (n = 81) TEEs were used to assess multiple quantitative measurements of the mechanism and severity of MR. By 2-dimensional TEE, leaflet tenting area, anterior and posterior leaflet angles, mitral annulus diameter, left ventricular (LV) end-systolic volume index, LV ejection fraction (LVEF), and sphericity index (p <0.05 for all) were significantly different across MR grades. By 3-dimensional TEE, mitral annulus area, leaflet tenting area, LV end-systolic volume index, LVEF, and sphericity index (p <0.05 for all) were significantly different across MR grades. A multivariate analysis showed a trend for annulus area (p = 0.069) and LV end-systolic volume index (p = 0.071) to predict effective regurgitant orifice area and for annulus area (p = 0.018) and LV end-systolic volume index (p = 0.073) to predict vena contracta area. In the STICH trial, multiple quantitative parameters of the mechanism of functional MR are related to MR severity. The mechanism of functional MR in ischemic cardiomyopathy is heterogeneous, but no single variable stands out as a strong predictor of quantitative severity of MR.

Mild expression of mitral valve prolapse in the Framingham offspring: expanding the phenotypic spectrum

BACKGROUND

Mitral valve (MV) prolapse (MVP) is a common disorder associated with mitral regurgitation, endocarditis, heart failure, and sudden death. Nondiagnostic morphologies have been described in the familial context and may represent early expression of MVP in those genetically predisposed. The aim of this study was to explore the spectrum of MVP abnormalities in the community and compare their clinical and echocardiographic features.

METHODS

We measured annular diameter MV leaflet displacement, thickness, anterior and posterior leaflet projections onto the annulus, MV leaflet coaptation height (posterior MV leaflet projection/annular diameter), and MR jet height in 296 individuals of the Framingham Offspring Study with MVP (n = 77), the "abnormal anterior coaptation" (AAC) phenotype (n = 11) or "minimal systolic displacement" (MSD) (n = 57), and 151 age-matched and sex-matched referents with no MVP or its nondiagnostic forms.

RESULTS

AAC did not meet diagnostic displacement criteria but resembled MVP with regard to annular diameter and leaflet thickness (P > .05 for both). AAC was similar to posterior MVP with regard to posterior leaflet asymmetry and an anteriorly shifted coaptation (P = .91). Compared to patients with MSD and referents, patients with AAC had greater leaflet coaptation height, thickness, and annular diameter (P < .05 for all). MSD shared the posterior leaflet asymmetry with MVP, but the coaptation point was more posterior (coaptation height = 31% vs. 42%, P < .0001), as seen in referents. A higher proportion of patients with MVP had jet height ≥ 2 mm (mild or greater MR) compared with the other participants (44% vs. 16%, P < .0001).

CONCLUSIONS

Nondiagnostic morphologies are observed in the community and share the common feature of posterior leaflet asymmetry with MVP. AAC and MSD may thus represent early expressions of MVP. Longitudinal studies are warranted to elucidate the natural history of these phenotypes.

Comparison of real-time three-dimensional transesophageal echocardiography to two-dimensional transesophageal echocardiography for quantification of mitral valve prolapse in patients with severe mitral regurgitation

Real-time 3-dimensional (3D) transesophageal echocardiography (TEE) provides more accurate geometric information on the mitral valve (MV) than 2-dimensional (2D) TEE. The aim of this study was to quantify MV prolapse using real-time 3D TEE in patients with severe mitral regurgitation. In 102 patients with severe mitral regurgitation due to MV prolapse and/or flail, 2D TEE quantified MV prolapse, including prolapse gap and width in the commissural view. Three-dimensional TEE also determined prolapse gap and width with the use of the 3D en face view. On the basis of the locations of MV prolapse, all patients were classified into group 1 (pure middle leaflet prolapse, n = 50) or group 2 (involvement of medial and/or lateral prolapse, n = 52). Prolapse gap and prolapse width determined by 3D TEE were significantly greater than those by 2D TEE (all p values <0.001). The differences in prolapse gap and prolapse width between 2D TEE and 3D TEE were significantly greater in group 2 than group 1 (Δ gap 1.3 ± 1.4 vs 2.4 ± 1.8 mm, Δ width 2.5 ± 3.0 vs 4.4 ± 5.1 mm, all p values <0.01). The differences in prolapse gap and width between 2D TEE and 3D TEE were best correlated with 3D TEE-derived prolapse width (r = 0.41 and r = 0.74, respectively). Two-dimensional TEE underestimated the width of MV prolapse and leaflet gap compared to 3D TEE. Two-dimensional TEE could not detect the largest prolapse gap and width, because of the complicated anatomy of the MV. In conclusion, 3D TEE provided more precise quantification of MV prolapse than 2D TEE.

Mechanism and severity of mitral regurgitation by transesophageal echocardiography in patients referred for percutaneous valve repair

Percutaneous mitral valve repair with the MitraClip has been shown to decrease mitral regurgitation (MR) severity, left ventricular volumes, and functional class in patients with severe (3+ or 4+) MR. Determination of which patients are optimal candidates for MitraClip therapy versus surgery has not been rigorously evaluated. Transesophageal echocardiography was prospectively performed in 113 consecutive patients referred for potential MitraClip therapy under the REALISM continued access registry. MR severity was assessed quantitatively in all patients. Mitral valve anatomy and feasibility of MitraClip placement were assessed by transesophageal echocardiography and clinical parameters. MR was degenerative (mitral valve prolapse) in 60 patients (53%), functional (anatomically normal) in 44 (39%), and thickened with restricted motion (Carpentier IIIB classification) in 9 (8%). MR was mild in 19 patients (17%), moderate in 27 (24%), and severe (3 to 4+) in 67 (59%) by Transesophageal echocardiography. MitraClip placement was performed in only 17 of 113 patients (15%); all were successful. Surgical mitral valve repair was performed in 25 patients (22%), mitral valve replacement in 12 (11%). Most patients (59 of 113, 52%) were treated medically, usually because MR was not severe enough to warrant intervention. In conclusion, most patients referred for MitraClip therapy do not have severe enough MR to warrant intervention. Of those with clinical need for intervention, surgery is more often recommended for anatomic or clinical reasons. Three-dimensional transesophageal echocardiography with quantitative assessment of MR severity is helpful in evaluating these patients.

Direct measurement of vena contracta area by real-time 3-dimensional echocardiography for assessing severity of mitral regurgitation

We tested the hypothesis that the vena contracta (VC) cross-sectional area in patients with mitral regurgitation (MR) can be reproducibly measured by real-time 3-dimensional (3D) echocardiography and correlates well with the volumetric effective regurgitant orifice area (EROA). Earlier MR repair requires accurate noninvasive measures, but practically, the VC area is difficult to image in 2-dimensional views, which are often oblique to it. 3D echocardiography can provide an otherwise unobtainable true cross-sectional view. In 45 patients with mild or greater MR, 44% eccentric, 2-dimensional and 3D VC areas were measured and correlated with the EROA derived from the regurgitant stroke volume. Real-time 3D echocardiography of the VC area correlated and agreed well with the EROA for both central and eccentric jets (r(2) = 0.86, SEE 0.02 cm(2), difference 0.04 +/- 0.06 cm(2), p = NS). For eccentric jets, 2-dimensional echocardiography overestimated the VC width compared with 3D echocardiography (p = 0.024) and correlated more poorly with the EROA (r(2) = 0.61 vs 0.85, p <0.001), causing clinical misclassification in 45% of patients with eccentric MR. The interobserver variability for the 3D VC area was 0.03 cm(2) (7.5% of the mean, r = 0.95); the intraobserver variability was 0.01 cm(2) (2.5% of the mean, r = 0.97). In conclusion, real-time 3D echocardiography accurately and reproducibly quantified the vena contracta cross-sectional area in patients with both central and eccentric MR. Rapid acquisition and intuitive analysis promote practical clinical application of this central, directly visualized, measure and its correlation with outcome.

Real-time 3-Dimensional Color Doppler Flow of Mitral and Tricuspid Regurgitation: Feasibility and Initial Quantitative Comparison with 2-Dimensional Methods

BACKGROUND

Visualization of valvular regurgitation using 3-dimensional (3D) echocardiography has been attempted but not routinely performed to date because of technical limitations. With the recent development of a fully sampled matrix-array probe, real-time color flow imaging allows display and analysis of regurgitant jets. Accordingly, the aim of this study was 2-fold. We: (1) investigated the feasibility of transthoracic, real-time visualization of 3D color flow jets; and (2) compared conventional 2-dimensional (2D) Doppler/color flow methods of quantitation (ie, 2D jet/left atrial [LA] area, flow convergence, and vena contracta [VC]) to 3D-derived measurements (3D jet/LA volume, flow convergence, and VC).

METHOD

In all, 56 patients with good acoustic windows and varying degrees of mitral regurgitation (MR) (n = 32) and tricuspid regurgitation (TR) (n = 24) scheduled for a routine echocardiogram were studied. Using a broadband transducer, 2D color Doppler imaging of TR and MR jets was performed to obtain jet/atrial area ratio, effective regurgitant orifice area, and VC measurements. Subsequently, real-time 3D echocardiography imaging of these jets was performed and analyzed offline using software, resulting in jet/atrial volume ratio, effective regurgitant orifice area, and VC (major and minor axes).

RESULTS

Of the 56 patients recruited into the study, 86% had sufficient data quality for analysis (87.5% in patients with MR and 83% in patients with TR). Both LA and right atrium were adequately visualized in all patients. Manually traced 3D MR and TR volumes had good agreement when compared with proximal isovelocity surface area-derived volumes (r = 0.7, y = 0.4x + 6.4; and r = 0.8, y = 1.1x + 5.1; respectively) with minimal underestimation and overestimation of volumes for MR and TR (8 and 7 mL, respectively), but with relatively wide limits of agreement for MR (28 mL) versus TR (12 mL). When comparing 3D MR jet/LA volume ratios and TR jet/right atrial volume ratios to 2D MR jet/LA area and 2D TR jet/right atrial area ratios, the former were significantly smaller. The 3D minimum and maximum VC diameter for MR were significantly different compared with those measured with 2D (minimum diameter = 0.7 +/- 0.1 cm, P < .01; maximum diameter = 1.1 +/- 0.5 cm, P < .02 vs 2D = 0.8 +/- 0.3 cm). Conversely, the TR VC minimum diameter was similar but maximum diameter measurements were larger in 3D compared with 2D (3D = 1.3 +/- 0.6 cm vs 2D = 0.7 +/- 0.2 cm, P < .001).

CONCLUSION

Three-dimensional echocardiography of color flow Doppler of MR and TR jets was feasible. Quantitative methods using 3D echocardiography such as MR and TR volumes correlated well with 2D flow convergence methods. TR VC has more of an elliptic shape, whereas MR is more circular or oval when visualized in 3D. Regurgitant/atrial volume ratios provide a new method of assessing the severity of regurgitant lesions; however, 3D volume-derived ratios were comparatively smaller than those measured with 2D echocardiography.

Perioperative transesophageal echocardiographic evaluation of the native mitral valve

During the past few decades, the effect of intraoperative transesophageal echocardiography's (TEE) influence on perioperative cardiac surgical decision making has become increasingly more appreciated. To date, there are no prospective, large-scale, randomized trials that have specifically identified a consistent, independent advantage for intraoperative TEE. However, data from several clinical investigations have consistently implicated an important, clinically significant, and cost-effective role for TEE as a safe and valuable hemodynamic monitor in identifying high-risk patients, in assisting in the determination of the definitive surgical approach, and in providing a timely post-cardiopulmonary bypass evaluation of the procedure, thereby allowing for the opportunity to immediately re-intervene or to at least triage patients appropriately. In addition, intraoperative TEE has been instrumental in diagnosing cardiac and associated great vessel pathology and in identifying structural abnormalities, including the presence and extent of congenital abnormalities, aortic disease, intracardiac masses, and pericardial disease. Intraoperative TEE, however, has perhaps been most useful for the perioperative evaluation of cardiac valvular disease, especially during surgical procedures involving the mitral valve. This article will focus primarily on the role of intraoperative TEE in defining mitral valve anatomy, the pathogenesis and mechanism of mitral valve pathology, and its influence on perioperative clinical decision making in patients undergoing mitral valve surgery.

Atrial fibrillatory rate and risk of left atrial thrombus in atrial fibrillation

AIMS

In atrial fibrillation (AF), a relation between electrocardiogram (ECG) fibrillatory wave amplitude and thrombus formation has been sought for long with conflicting results. In contrast, the possible relation between atrial fibrillatory rate obtained from the surface ECG and left atrial thrombus formation in patients with AF is unknown and was consequently evaluated in this study.

METHODS AND RESULTS

One-hundred and twenty-five patients (mean age 64 +/- 12 years, 72% male) with persistent non-valvular AF (mean duration 28 +/- 80 days) undergoing transesophageal echocardiography were studied. In all patients, standard 12-lead ECG recordings were acquired before the examination. Atrial fibrillatory rate was determined using spatiotemporal QRST cancellation and time-frequency analysis of lead V1. Atrial fibrillatory rate measured 401 +/- 63 fibrillations per minute (fpm, range 235-566 fpm) and was related with age (R = -0.326, P < 0.001), ventricular rate (R = -0.202, P = 0.024), gender (407 +/- 62 in males vs. 387 +/- 64 fpm in females, P = 0.038) but not AF duration (R = 0.088, P = 0.374), presence of lone AF (408 +/- 66 vs. 394 +/- 58 fpm, P = 0.228), or beta-blocker or calcium channel blocker treatment (398 +/- 63 vs. 405 +/- 62 fpm, P = 0.556). Age was the only independent predictor of fibrillatory rate (B = -1.714, P < 0.001). In patients with left atrial thrombus (n = 10), spontaneous echo contrast (SEC) was more frequently present (70 vs. 29 %, p = 0.007) and left atrial appendage (LAA) outflow velocity was lower (26 +/- 20 vs. 37 +/- 15 cm/s, P = 0.012) than in patients without thrombus (n = 115). In contrast, mean fibrillatory rate, which showed a weak inverse correlation with LAA velocity (R = -0.118, P = 0.048) was not different between both groups (380 +/- 56 vs. 403 +/- 63 fpm, P = 0.226). Similarly, presence of thrombus and SEC combined was not related with fibrillatory rate.

CONCLUSION

Atrial fibrillatory rate obtained from surface ECG lead V1 is not a risk marker for left atrial thrombus formation in AF.

The Crossed Swords Sign: Insights into the Dilemma of Repair in Bileaflet Mitral Valve Prolapse

BACKGROUND

The need for bileaflet repair in bileaflet mitral valve prolapse (MVP) remains controversial. Will anterior leaflet prolapse resolve with posterior leaflet repair or should both leaflets be addressed? Single-leaflet MVP produces oppositely directed mitral regurgitant jets. Some patients show two crossed jets oppositely directed from the coaptation zone. We hypothesized that these indicate bileaflet lesions requiring complex repair.

METHODS

Echocardiograms and surgical reports of 52 consecutive patients with MVP undergoing surgery were reviewed.

RESULTS

First, all 14 patients with two oppositely directed jets had prolapse of more than one leaflet. Each jet was related to discrete leaflet distortions causing malcoaptation. Six underwent valve replacement. Seven had both leaflets repaired. One had posterior leaflet repair and annuloplasty, with persistent mitral regurgitation requiring valve replacement. Second, 36 of 38 patients with single jets had single-leaflet MVP. One underwent replacement; all others did well with single-leaflet repair. Two patients with bileaflet MVP but only one jet did well with single-leaflet repair or annuloplasty.

CONCLUSION

This crossed swords sign is an important clue to bileaflet mechanism of mitral regurgitation in MVP, associated with complex repair procedures. Thus, it provides a clue in the dilemma of bileaflet versus single-leaflet repair.

Transthoracic and Transesophageal Echocardiographic Assessment of Mitral Regurgitation Severity: Usefulness of Qualitative and Semiquantitative Techniques

In this report, we review the advantages, limitations, and optimal utilization of various transthoracic and transesophageal echocardiographic (TTE and TEE) methods used for assessing mitral regurgitation (MR) as published in full-length, peer-reviewed articles since the color Doppler era began in 1984. In addition, comparison is made to other imaging modalities including catheter-based, magnetic resonance and surgical assessment of MR. Although left ventricular (LV) angiography has been traditionally used for validation of various TTE methods and is time-honored, its considerable limitations preclude it from being a real "gold standard." Based on the reviewed literature, no clear "gold standard" for the assessment of MR can be identified at present, but newly emerging TTE and TEE techniques, such as three-dimensional color Doppler, may have the potential to overcome some of the limitations of the two-dimensional methods.

Mechanism of recurrent ischemic mitral regurgitation after annuloplasty: continued LV remodeling as a moving target

BACKGROUND

Patients who undergo ring annuloplasty for ischemic mitral regurgitation (MR) often have persistent or recurrent MR. This may relate to persistent leaflet tethering from left ventricle (LV) dilatation that is not relieved by ring annuloplasty. Therefore, the purpose of this study was to test the hypothesis that recurrent MR in patients after ring annuloplasty relates to continued LV remodeling.

METHODS AND RESULTS

Serial echoes were reviewed in 30 patients (aged 72+/-11 years) who showed recurrent MR late (47+/-27 months) versus early (3.8+/-5.8 months) after ring annuloplasty for ischemic MR during coronary artery bypass grafting without interval infarction. Patients with intrinsic mitral valve disease were excluded. Echocardiographic measures of MR (vena contracta and jet area/left atrial area) and LV remodeling (LV dimensions, volumes, and sphericity) were assessed at each stage. The degree of MR increased from mild to moderate, on average, from early to late postoperative stages, without significant change in LV ejection fraction. Changes in MR paralleled increases in LV volumes and sphericity index at end-systole and end-diastole. The only independent predictor of late postoperative MR was LV sphericity index at end-systole.

CONCLUSIONS

Recurrent MR late after ring annuloplasty is associated with continued LV remodeling, emphasizing its dynamic relation to the LV.

Assessment of severity of mechanical prosthetic mitral regurgitation by transoesophageal echocardiography

OBJECTIVE

To evaluate the ability of colour Doppler transoesophageal echocardiography (TOE) to assess quantitatively prosthetic mitral valve insufficiency.

METHODS

47 patients were studied with multiplane TOE and cardiac catheterisation. Proximal jet diameter was measured as the largest diameter of the vena contracta. Regurgitant area was measured by planimetry of the largest turbulent jet during systole. Flow convergence zone was considered to be present when a localised area of increased systolic velocities was apparent on the left ventricular side of the valve prosthesis. Pulmonary vein flow velocity was measured at peak systole and diastole.

RESULTS

Mean (SD) proximal jet diameter was 0.63 (0.16) cm, with good correlation with angiographic grades (r = 0.83). Mean (SD) maximum colour jet area was 7.9 (2.5) cm2 (r = 0.69) with worse correlation if a single imaging plane was used for measurements (r = 0.62). The ratio of systolic to diastolic peak pulmonary flow velocity averaged 0.7 (1.3) cm (r = -0.66) with better correlation (r = -0.71) if patients with atrial fibrillation were excluded. Mean (SD) regurgitant flow rate was 168 (135) ml/s and regurgitant orifice area was 0.56 (0.43) cm2, with good correlation with angiography (r = 0.77 and r = 0.78, respectively).

CONCLUSIONS

TOE correctly identified angiographically severe prosthetic mitral regurgitation, mainly by the assessment of the flow convergence region and the proximal diameter of the regurgitant jet.

Assessing prosthetic mitral valve regurgitation by transoesophageal echo/Doppler

Transoesophageal echocardiography has greatly improved our ability to detect structural and regurgitant abnormalities associated with prosthetic mitral valves.

Leaflet concavity: a rapid visual clue to the presence and mechanism of functional mitral regurgitation

Repairing mitral regurgitation (MR) requires an understanding of its mechanism. Evaluating restricted leaflet closure in functional MR is challenging. Tenting area between leaflets and annulus in long-axis (LAX) views correlates with MR, but is positive even in control subjects; in the 4-chamber view, the incomplete mitral leaflet closure (IMLC) tenting pattern may be subtle and variable. We tested the hypothesis that leaflet concavity toward the left atrium in the LAX view, a rapid visual clue indicating abnormal tethering predominantly by intermediate chords, is a strong indicator of functional MR. We reviewed 90 patients: 40 with inferior myocardial infarction and ejection fraction > or = 50%; 40 with global left ventricular dysfunction and ejection fraction < 50%; and 10 control subjects. We assessed leaflet shape (concave or convex toward the left atrium) and maximum systolic proximal MR jet width in the LAX views. To quantify shape, we measured the leaflet concavity area between the anterior leaflet and a line connecting its ends. Conventional IMLC area was also assessed. Patients with leaflet concavity had significantly greater MR than those without this finding (jet width of 4.6 +/- 0.7 vs 0.5 +/- 0.1 mm, P <.0001), indicating mild-moderate versus trace MR, with differences comparable in those with inferior myocardial infarction and left ventricular dysfunction. Leaflet concavity area most strongly predicted MR by multivariate regression (R(2) = 0.7). Conventional IMLC area did not uniquely distinguish patients with or without MR and correlated more weakly with MR (R(2) = 0.30 vs 0.73). Mitral leaflet concavity in the LAX view provides rapid and reliable recognition of functional MR, with greater reliability than IMLC area. This shape, consistent with tethering by intermediate chords, may have implications for potential intervention.

What does transesophageal echocardiography add to valvular heart surgery?

No single monitoring tool in the last decade has had more of an effect on intraoperative decision making and surgical management of cardiac valvular pathologies than has TEE. It has become the standard of care for evaluating reparative valvular procedures, thus providing an immediate gauge of the surgical results and helping to avoid suboptimal surgical outcomes. As the technology of TEE and its application advance, so too should the ability to diagnose and manage valvular pathologies, broaden the range of surgical options, and ultimately improve patient outcomes.

Feasibility of simplifying balloon mitral valvuloplasty by obviating left-sided cardiac catheterization using on-line guidance with transesophageal echocardiography

STUDY OBJECTIVES

The purpose of this study was to evaluate the feasibility of simplifying balloon mitral valvuloplasty through the obviation of left-sided cardiac catheterization using on-line guidance with transesophageal echocardiography in patients with mitral stenosis.

SETTING

A tertiary care medical center

DESIGN

Patients who were eligible for balloon mitral valvuloplasty were enrolled into the study if they had no evidence of ischemic heart disease. Sixty-six patients (50 women and 16 men) met the criteria. Balloon mitral valvuloplasty was performed through right-sided cardiac catheterization using adjunctive on-line guidance with transesophageal echocardiography. Left-sided catheterization was obviated.

MEASUREMENT AND RESULTS

Balloon mitral valvuloplasty was smoothly performed in all patients. Successful dilatation (postprocedural mitral orifice area, > 1.5 cm(2); or increment in mitral orifice area, >or= 50%) was achieved in 50 patients (75.8%). The mean (+/- SD) mitral orifice area increased from 1.08 +/- 0.23 cm(2) to 1.68 +/- 0.39 cm(2) (p = 0.0000). There were no in-hospital deaths, no patients with cardiac tamponade, or complications necessitating an emergency cardiac operation. The mean fluoroscopy time was 7.6 +/- 3.9 min, and the total procedure time was 50.2 +/- 15.0 min.

CONCLUSION

It is feasible and safe to simplify balloon mitral valvuloplasty by obviating left-sided cardiac catheterization in selected patients with mitral stenosis using adjunctive on-line guidance with transesophageal echocardiography.

New index for grading the severity of aortic regurgitation based on the cross-sectional area of vena contracta measured by color Doppler flow mapping

This study was designed to examine whether the cross-sectional area of vena contracta measured by color Doppler flow mapping (CFM) could be used for assessing aortic regurgitation (AR) and developing an index for grading AR. The 75 study patients with AR were classified into quadrant grades according to New York Heart Association functional class, regurgitant fraction, left ventricular (LV) end-diastolic dimension and LV end-systolic dimension. Using CFM, the cross-sectional area of the vena contracta was measured and it could distinguish all grades without significant overlap. An area of less than 0.10 cm(2) corresponded to Grade 1, 0.10-0.19 cm(2) corresponded to Grade 2, 0.20-0.29 cm(2) corresponded to Grade 3 and an area of more than 0.30 cm(2) corresponded to Grade 4. An area of vena contracta of more than 0.30 cm(2) identified high-scoring AR (Grade 4) in 11 of 11 (sensitivity 100%) and correctly predicted the absence of high-scoring AR in 60 of 64 (specificity 94%). Conversely, there was considerable overlap between the jet distances with the clinical grades. The cross-sectional area of the vena contracta measured by CFM can provide a simple quantitative assessment of AR that correlates well with the clinical grade of AR.

Vena contracta width measurement: theoretic basis and usefulness in the assessment of valvular regurgitation severity

In patients with valvular regurgitation, the regurgitation jet can be observed by Doppler color flow imaging. Vena contracta is defined as the narrowest part of the jet, just distal to the regurgitant orifice. Vena contracta dimensions reflect the severity of regurgitation. Vena contracta diameter, usually easy to measure in clinical practice, is well correlated with the effective regurgitant orifice area and the regurgitant volume. Cutoff values have been determined to identify severe regurgitation for mitral, aortic, and tricuspid valves. In clinical practice, determination of vena contracta diameter is a useful and simple method for assessment of valvular regurgitation. In the future, assessment of complex jet regurgitations will probably benefit from the contribution of three-dimensional Doppler flow imaging, which should improve the performances of the method.

Usefulness of peak mitral inflow velocity to predict severe mitral regurgitation in patients with normal or impaired left ventricular systolic function

BACKGROUND

The aim of this study was to evaluate the reliability of peak mitral inflow (E-wave) velocity, which was thought to be easier and more practical than qualitative and quantitative methods used to grade mitral regurgitation (MR) in patients both with normal and low left ventricular (LV) ejection fraction (EF). It is known that peak E-wave velocity increases in MR. But correlation of this increase with regurgitant fraction (RF), its usefulness in grading MR, and the effect of EF on peak E-wave velocity have not been studied in detail.

METHODS

We prospectively examined 135 consecutive patients with varying grades of MR with echocardiography. MR was evaluated both qualitatively and quantitatively, and concordance of these 2 methods was determined. Peak E-wave velocity, A-wave velocity, and E-wave deceleration time were measured and the E/A ratio was calculated. LV isovolumetric relaxation and contraction times were measured. Different MR groups classified by RF were compared with each other.

RESULTS

Concordance of quantitative and qualitative evaluation was low in patients with low EF (kappa 0.37 vs 0.65). Peak E-wave velocity and E/A ratio showed significant differences between MR groups. Peak E-wave velocity correlated with the RF and EF (r = 0.47, r = 0.33, respectively, P <.001). Sensitivity, specificity, and negative predictive value of peak E-wave velocity >1.2 m/s suggesting severe MR were found to be different in patients with normal and low EF (96% vs 66%, 78% vs 83%, 97% vs 78%, respectively). E-wave deceleration, LV isovolumetric relaxation, and contraction time did not show a correlation with RF.

CONCLUSION

Peak E-wave velocity is a screening method that could be used in common for determining severity of MR semiquantitatively, especially in patients with normal EF.

The adequacy of basic intraoperative transesophageal echocardiography performed by experienced anesthesiologists

Transesophageal echocardiography (TEE) may improve intraoperative decision-making and patient outcome if it is performed and interpreted correctly. After revising our TEE examination to fulfill the published guidelines for basic TEE practitioners, we prospectively evaluated the ability of our cardiac anesthesiologists (all very experienced with TEE) to record and interpret this revised examination. Educational aids and regular TEE performance feedback were provided to the anesthesiologists. Their interpretations were compared with the independently determined results of experts. Compared with their own historical controls (42% recording rate), all anesthesiologists showed significant improvement in their ability to record a basic intraoperative TEE examination resulting in 81% (P < 0.0001) of all required images being recorded: 88% before cardiopulmonary bypass, 77% immediately after bypass, and 64% after chest closure. Seventy-nine percent of the images recorded at baseline were correctly interpreted, 6% were incorrectly interpreted, and 15% were not evaluated. Our attempt to assess compliance with published guidelines for basic intraoperative TEE resulted in a marked improvement in our intraoperative TEE practice. Most, but not all, standard cross-sections are recorded or interpreted correctly, even by highly experienced and motivated practitioners.

IMPLICATIONS

Experienced cardiac anesthesiologists can obtain and correctly interpret most basic intraoperative transesophageal echocardiograms.

Assessment of aortic regurgitation by transesophageal color Doppler imaging of the vena contracta: validation against an intraoperative aortic flow probe

OBJECTIVES

This study was performed to validate the accuracy of color flow vena contracta (VC) measurements of aortic regurgitation (AR) severity by comparing them to simultaneous intraoperative flow probe measurements of regurgitant fraction (RgF) and regurgitant volume (RgV).

BACKGROUND

Color Doppler imaging of the vena contracta has emerged as a simple and reliable measure of the severity of valvular regurgitation. This study evaluated the accuracy of VC imaging of AR by transesophageal echocardiography (TEE).

METHODS

A transit-time flow probe was placed on the ascending aorta during cardiac surgery in 24 patients with AR. The flow probe was used to measure RgF and RgV simultaneously during VC imaging by TEE. Flow probe and VC imaging were interpreted separately and in blinded fashion.

RESULTS

A good correlation was found between VC width and RgF (r = 0.85) and RgV (r = 0.79). All six patients with VC width >6 mm had a RgF >0.50. All 18 patients with VC width <5 mm had a RgF <0.50. Vena contracta area also correlated well with both RgF (r = 0.81) and RgV (r = 0.84). All six patients with VC area >7.5 mm2 had a RgF >0.50, and all 18 patients with a VC area <7.5 mm2 had a RgF <0.50. In a subset of nine patients who underwent afterload manipulation to increase diastolic blood pressure, RgV increased significantly (34 +/- 26 ml to 41 +/- 27 ml, p = 0.042) while VC width remained unchanged (5.4 +/- 2.8 mm to 5.4 +/- 2.8 mm, p = 0.41).

CONCLUSIONS

Vena contracta imaging by TEE color flow mapping is an accurate marker of AR severity. Vena contracta width and VC area correlate well with RgF and RgV obtained by intraoperative flow probe. Vena contracta width appears to be less afterload-dependent than RgV.

Quantitative assessment of severity of ventricular septal defect by three-dimensional reconstruction of color Doppler-imaged vena contracta and flow convergence region

BACKGROUND

The aim of the present study was to investigate the feasibility and potential value of the computer-controlled, 3D, echocardiographic reconstruction of the color Doppler-imaged vena contracta (CDVC) and the flow convergence (FC) region as a means of accurately and quantitatively estimating the severity of a ventricular septal defect (VSD).

METHODS AND RESULTS

We performed a 3D reconstruction of the CDVC and the FC region in 19 patients with an isolated VSD using an ultrasound system interfaced with a Tomtec computer. The variable asymmetric geometry of the CDVC and the FC region could be 3D-visualized in all patients. The 3D-measured areas of CDVC correlated well with volumetric measurements of the severity of VSD (r=0.97, P:<0.001). Regression analysis between the shunt flow rate (calculated from the product of the area of CDVC and the continuous Doppler-derived velocity time integral) and the corresponding reference results (calculated by cardiac catheterization) demonstrated a close correlation (r=0.95, P:<0.001). There was also a good correlation between shunt flow rates calculated using the conventional 2D, 1-axis measurement of the FC isovelocity surface area with the hemispheric assumption (r=0.95, P:<0.001); shunt flow rates calculated using 3D, 3-axis measurements of the FC region (r=0.97, P:<0.01); and reference results by cardiac catheterization. However, the 2D method substantially underestimated the actual shunt flow rate.

CONCLUSIONS

The 3D reconstruction of the CDVC and the FC region may aid in quantifying the severity of VSD.

Left atrial appendage flow in nonrheumatic atrial fibrillation : relationship with pulmonary venous flow and ECG fibrillatory wave amplitude

OBJECTIVE

This study was conducted (1) to examine the relationship between left atrial appendage (LAA) flow velocity and pulmonary venous flow (PVF) variables during nonrheumatic atrial fibrillation (AF), and (2) to determine whether a reduction in LAA flow is reflected by the fibrillatory wave amplitude on the surface ECG.

BACKGROUND

Although LAA Doppler echocardiographic signals provide information regarding the velocity and direction of flow only for a localized narrow sample, systolic PVF represents in part the global left atrial function, mainly relaxation. Controversy exists about whether the amplitude of fibrillatory waves recorded on the surface ECG correlates with LAA flow velocity during AF.

MEASUREMENTS AND RESULTS

Thirty-three patients (20 men, 13 women; mean [+/- SD] age, 61 +/- 11 years) with nonrheumatic AF undergoing transthoracic and transesophageal echocardiography were studied. A correlation between LAA flow velocity and systolic PVF variables (peak systolic velocity, R: = 0.450, p = 0.009; velocity-time integral of systolic flow, R = 0.491, p = 0.004; systolic fraction of PVF, R: = 0.627, p < 0.0001) was observed. Patients with a low LAA flow profile (< 25 cm/s) had a reduced systolic PVF. Longer AF duration and the occurrence of moderate mitral regurgitation were related to reduced LAA flow. AF was subdivided into coarse (peak-to-peak fibrillatory amplitude > or = 1 mm) or fine (< 1 mm) in standard ECG lead V1. There was no association between the coarseness of AF and the LAA flow profile.

CONCLUSION

In patients with nonrheumatic AF, a reduction in LAA flow velocity correlates with a reduction in systolic PVF. These hemodynamic changes are not reflected by the ECG fibrillatory wave amplitude.

The power-velocity integral at the vena contracta: A new method for direct quantification of regurgitant volume flow

BACKGROUND

Noninvasive quantification of regurgitation is limited because Doppler measures velocity, not flow. Because backscattered Doppler power is proportional to sonified blood volume, power times velocity should be proportional to flow rate. Early studies, however, suggested that this held only for laminar flow, not for regurgitant jets, in which turbulence and fluid entrainment augment scatter. We therefore hypothesized that this Doppler power principle can be applied at the proximal vena contracta, where flow is laminar before entrainment, so that the power-times-velocity integral should vary linearly with flow rate and its time integral with stroke volume (SV).

METHODS AND RESULTS

This was tested in vitro with steady and pulsatile flow through 0.07- to 0.8-cm(2) orifices and in 36 hemodynamic stages in vivo, replacing the left atrium with a rigid chamber and column for direct visual recording of mitral regurgitant SV (MRSV). In 12 patients, MRSV was compared with MRI mitral inflow minus aortic outflow and in 11 patients with 3D echo left ventricular ejection volume-Doppler aortic forward SV. Vena contracta power in the narrow high-velocity spectrum from a broad measuring beam was calibrated against that from a narrow reference beam of known area. Calculated and actual flow rates and SV correlated well in vitro (r=0.99, 0.99; error=-1.6+/-2.5 mL/s, -2. 4+/-2.9 mL), in vivo (MRSV: r=0.98, error=0.04+/-0.87 mL), and in patients (MRSV: r=0.98, error=-2.8+/-4.5 mL).

CONCLUSIONS

The power-velocity integral at the vena contracta provides an accurate direct measurement of regurgitant flow, overcoming the limitations of existing Doppler techniques.

Assessment of severity of aortic regurgitation using the width of the vena contracta: A clinical color Doppler imaging study

BACKGROUND

The width of the vena contracta (VC-W), the smallest area of regurgitant flow, reflects the degree of valvular regurgitation and is measurable by color Doppler imaging, but this method has not been validated in aortic regurgitation (AR).

METHODS AND RESULTS

We prospectively examined 79 patients with isolated AR and 80 patients without regurgitation. The VC-W was measured from the long-axis parasternal view and compared with 2 simultaneous reference methods (quantitative Doppler and 2D echocardiography). In patients without regurgitation, the agreement between methods was excellent. In patients with AR, good correlations (all P<0.0001) were obtained between VC-W and effective regurgitant orifice (ERO) area and regurgitant volume recorded by quantitative Doppler (r=0.89 and 0.90, respectively) and 2D echocardiographic (r=0.90 and 0.89, respectively) methods. These correlations were similar with eccentric or central jets (all P>0.60). The other methods used showed good correlations of VC-W with aortographic grading of AR (n=8, r=0.82, P=0.01), with the proximal flow convergence method (n=53, r=0.85, P<0.0001), and with left ventricular end-diastolic volume (r=0.81, P<0.0001). Sensitivity and specificity of VC-W >/=6 mm for diagnosing severe AR (ERO >/=30 mm(2)) were 95% and 90%, respectively.

CONCLUSIONS

For assessment of the degree of AR, VC-W shows good correlations with simultaneous quantitative measures (regardless of jet direction), shows good correlations with other methods of assessment of AR, and provides a high diagnostic value for severe AR. VC-W is a simple, reliable method that can be used clinically as part of comprehensive Doppler echocardiographic assessment of AR.

Quantification of tricuspid regurgitation by measuring the width of the vena contracta with Doppler color flow imaging: a clinical study

OBJECTIVE

We sought to evaluate the vena contracta width (VCW) measured using color Doppler as an index of severity of tricuspid regurgitation (TR).

BACKGROUND

The VCW is a reliable measure of mitral and aortic regurgitation, but its value in measuring TR is uncertain.

METHODS

In 71 consecutive patients with TR, the VCW was prospectively measured using color Doppler and compared with the results of the flow convergence method and hepatic venous flow, and its diagnostic value for severe TR was assessed.

RESULTS

The VCW was 6.1+/-3.4 mm and was significantly higher in patients with, than those without, severe TR (9.6+/-2.9 vs. 4.2 +/- 1.6 mm, p<0.0001). The VCW correlated well with the effective regurgitant orifice (ERO) by the flow convergence method (r = 0.90, SEE = 0.17 cm2, p<0.0001), even when restricted to patients with eccentric jets (r = 0.93, p < 0.0001). The VCW also showed significant correlations with hepatic venous flow (r = 0.79, p < 0.0001), regurgitant volume (r = 0.77, p<0.0001) and right atrial area (r = 0.46, p< 0.0001). A VCW > or =6.5 mm identified severe TR with 88.5% sensitivity and 93.3% specificity. In comparison with jet area or jet/right atrial area ratio, the VCW showed better correlations with ERO (both p<0.01) and a larger area under the receiver operating characteristic curve (0.98 vs. 0.88 and 0.85, both p<0.02) for the diagnosis of severe TR.

CONCLUSIONS

The VCW measured by color Doppler correlates closely with severity of TR. This quantitative method is simple, provides a high diagnostic value (superior to that of jet size) for severe TR and represents a useful tool for comprehensive, noninvasive quantitation of TR.

Mitral regurgitation: comprehensive assessment by echocardiography

Two-dimensional and Doppler echocardiography have become the major modalities for the assessment of mitral regurgitation. The combined use of these techniques provides information regarding the morphology of the valvular apparatus as well as the severity of regurgitation. Transesophageal and three-dimensional echocardiography provide a more-detailed evaluation of valve morphology, which can be valuable in determining suitability for valve repair. In patients with severe mitral regurgitation, echocardiographic assessment of ventricular size and function plays a critical role in determining the optimal timing of surgery.

Real-time 3-dimensional volumetric ultrasound imaging of the vena contracta for stenotic valves with the use of echocardiographic contrast imaging: in vitro pulsatile flow studies

The purpose of our study was to investigate the utility of real-time 3-dimensional volumetric ultrasound coupled with echo contrast imaging to visualize and quantify effective flow areas for stenotic valves in vitro. Real-time 3-dimensional ultrasound imaging has recently emerged as a promising method for increasing the quantitative accuracy of echocardiography. Since the technique currently does not process Doppler information, its use for quantifying flow has not been studied. However, the use of contrast agents to visualize cardiac flows with the use of echocardiography should allow determination of mass-dependent flow parameters such as effective flow area (vena contracta area) for stenotic lesions. We used real-time 3-dimensional imaging in an in vitro stenotic valve model (areas 0.785 to 1.767 cm2) under pulsatile flow conditions (60 bpm; 40 to 80 mL/beat). An echo contrast agent was used to visualize the distal jet. Real-time 3-dimensional imaging provides simultaneous views of long-axis and short-axis (C-scan) image planes of the jet. The vena contracta was identified and measured by placing the C-scan line immediately distal to the orifice and measuring the cross-sectional flow area. System gain and postprocessing curve shape affected 3-dimensional areas; minimal gain and a custom curve produced best agreement to actual vena contracta areas measured with a previously validated laser method (y = 0.939x + 0.089; r = 0.98; standard error of estimate = 0.158 cm2). We conclude that real-time 3-dimensional ultrasound imaging coupled with a contrast agent can be used as an accurate yet simple clinical means of measuring effective flow areas for stenotic valves.

The Mitral Regurgitation Index: an echocardiographic guide to severity

OBJECTIVES

The purpose of this study was to develop a semiquantitative index of mitral regurgitation severity suitable for use in daily clinical practice and research.

BACKGROUND

There is no simple method for quantification of mitral regurgitation (MR). The MR Index is a semiquantitative guide to MR severity. The MR Index is a composite of six echocardiographic variables: color Doppler regurgitant jet penetration and proximal isovelocity surface area, continuous wave Doppler characteristics of the regurgitant jet and tricuspid regurgitant jet-derived pulmonary artery pressure, pulse wave Doppler pulmonary venous flow pattern and two-dimensional echocardiographic estimation of left atrial size.

METHODS

Consecutive patients (n = 103) with varying grades of MR, seen in the Adult Echocardiography Laboratory at UCSF, were analyzed retrospectively. All patients were evaluated for the six variables, each variable being scored on a four point scale from 0 to 3. The reference standards for MR were qualitative echocardiographic evaluation by an expert and quantitation of regurgitant fraction using two-dimensional and Doppler echocardiography. A subgroup of patients with low ejection fraction (EF < 50%) were also analyzed.

RESULTS

The MR Index increased in proportion to MR severity with a significant difference among the three grades in both normal and low EF groups (F = 130 and F = 42, respectively, p < 0.0001). The MR Index correlated with regurgitant fraction (r = 0.76, p < 0.0001). An MR Index > or =2.2 identified 26/29 patients with severe MR (sensitivity = 90%, specificity = 88%, PPV = 79%). No patient with severe MR had an MR Index <1.8 and no patient with mild MR had an MR Index >1.7.

CONCLUSIONS

The MR Index is a simple semiquantitative estimate of MR severity, which seems to be useful in evaluating MR in patients with a low EF.

Temporal variability of vena contracta and jet areas with color Doppler in aortic regurgitation: a chronic animal model study

OBJECTIVE

The purpose of our study was to determine the temporal variability of regurgitant color Doppler jet areas and the width of the color Doppler imaged vena contracta for evaluating the severity of aortic regurgitation.

METHODS

Twenty-nine hemodynamically different states were obtained pharmacologically in 8 sheep 20 weeks after surgery to produce aortic regurgitation. Aortic regurgitation was quantified by peak and mean regurgitant flow rates, regurgitant stroke volumes, and regurgitant fractions determined using pulmonary and aortic electromagnetic flow probes and meters balanced against each other. The regurgitant jet areas and the widths of color Doppler imaged vena contracta were measured at 4 different times during diastole to determine the temporal variability of this parameter.

RESULTS

When measured at 4 different temporal points in diastole, a significant change was observed in the size of the color Doppler imaged regurgitant jet (percent of difference: from 31.1% to 904%; 233% +/- 245%). Simple linear regression analysis between each color jet area at 4 different periods in diastole and flow meter-based severity of the aortic regurgitation showed only weak correlation (0.23 < r < 0.49). In contrast, for most conditions only a slight change was observed in the width of the color Doppler imaged vena contracta during the diastolic regurgitant period (percent of difference, vena contracta: from 2.4% to 12.9%, 5.8% +/- 3.2%). In addition, for each period the width of the color Doppler imaged vena contracta at the 4 different time periods in diastole correlated quite strongly with volumetric measures of the severity of aortic regurgitation (0.81 < r < 0.90) and with the instantaneous flow rate for the corresponding period (0.85 < r < 0.87).

CONCLUSIONS

Color Doppler imaged vena contracta may provide a simple, practical, and accurate method for quantifying aortic regurgitation, even when using a single frame color Doppler flow mapping image.

Mechanism of mitral regurgitation in hypertrophic cardiomyopathy: mismatch of posterior to anterior leaflet length and mobility

BACKGROUND

In hypertrophic cardiomyopathy, a spectrum of mitral leaflet abnormalities has been related to the mechanism of mitral systolic anterior motion (SAM), which causes both subaortic obstruction and mitral regurgitation. In the individual patient, SAM and regurgitation vary in parallel; clinically, however, great interindividual differences in mitral regurgitation can occur for comparable degrees of SAM. We hypothesized that these differences relate to variations in posterior leaflet length and mobility, restricting its ability to follow the anterior leaflet (participate in SAM) and coapt effectively.

METHODS AND RESULTS

Different mitral geometries produced surgically in porcine valves were studied in vitro. Comparable degrees of SAM resulted in more severe mitral regurgitation for geometries characterized by limited posterior leaflet excursion. Mitral geometry was also analyzed in 23 patients with hypertrophic cardiomyopathy by intraoperative transesophageal echocardiography. All had typical anterior leaflet SAM with significant outflow tract gradients but considerably more variable mitral regurgitation; therefore, regurgitation did not correlate with obstruction. In contrast, mitral regurgitation correlated inversely with the length over which the leaflets coapted (r= -0.89), the most severe regurgitation occurring with a visible gap. Regurgitation increased with increasing mismatch of anterior to posterior leaflet length (r=0.77) and decreasing posterior leaflet mobility (r= -0.79).

CONCLUSIONS

SAM produces greater mitral regurgitation if the posterior leaflet is limited in its ability to move anteriorly, participate in SAM, and coapt effectively. This can explain interindividual differences in regurgitation for comparable degrees of SAM. Thus, the spectrum of leaflet length and mobility that affects subaortic obstruction also influences mitral regurgitation in patients with SAM.