Validation of the proximal isovelocity surface area method for assessing mitral regurgitation in children

Standardization in paediatric echocardiographic reporting and critical interpretation of measurements, functional parameters, and prediction scores: a clinical consensus statement of the European Association of Cardiovascular Imaging of the European Society of Cardiology and the Association for European Paediatric and Congenital Cardiology

This document has been developed to provide a guide for basic and advanced reporting in paediatric echocardiography. Furthermore, it aims to help clinicians in the interpretation of echocardiographic measurements and functional data for estimating the severity of disease in different paediatric age groups. The following topics will be reviewed and discussed in the present document: (i) the general principle in constructing a paediatric echocardiographic report, (ii) the basic elements to be included, and (iii) the potential and limitation of currently employed tools used for disease severity quantification during paediatric reporting. A guide for the interpretation of Z-scores will be provided. Use and interpretation of parameters employed for quantification of ventricular systolic function will be discussed. Difficulties in the adoption of adult parameters for the study of diastolic function and valve defects at different ages and pressure and loading conditions will be outlined, with pitfalls for the assessment listed. A guide for careful use of prediction scores for complex congenital heart disease will be provided. Examples of basic and advanced (disease-specific) formats for reporting in paediatric echocardiography will be provided. This document should serve as a comprehensive guide to (i) structure a comprehensive paediatric echocardiographic report; (ii) identify the basic morphological details, measures, and functional parameters to be included during echocardiographic reporting; and (iii) correctly interpret measurements and functional data for estimating disease severity.

Mitral Regurgitation and Serum N-Terminal Pro-Brain Natriuretic Peptide Levels in Children: A Modification of Adult Criteria

Mitral regurgitation can result from congenital heart disease, rheumatic valve disease, or other congenital malformations of the mitral valve. Faulty valves require surgical repair or replacement. However, echocardiographic and biochemical parameters that inform surgical decision-making for adults may not be appropriate for children. To investigate whether adult parameters can be used in children, we correlated echocardiographic parameters with serum N-terminal pro-brain natriuretic peptide (NT-proBNP) levels in children with chronic mitral regurgitation. Our sample comprised 45 patients and 38 healthy children. M-mode measurements, left atrial and left ventricular volumes, and Doppler and tissue Doppler echocardiograms were collected. We graded mitral regurgitation according to European Association of Echocardiography recommendations and indexed effective regurgitant area, vena contracta, and regurgitant volume to body surface area. Patients were grouped by regurgitation severity (mild vs moderate or severe) and left ventricular end-systolic dimension (normal vs enlarged). The NT-proBNP level was higher in patients than in controls (P=0.003), higher in patients with moderate or severe regurgitation (P=0.02), and higher in patients with an enlarged left ventricle (P=0.003). Serum NT-proBNP levels correlated with effective regurgitant area (r=0.47; P=0.002), vena contracta width (r=0.46; P=0.003), regurgitant volume (r=0.32; P=0.04), left ventricular end-systolic diameter (r=0.58; P <0.001), and left atrial diameter (r=0.62; P <0.001). An NT-proBNP value of 66 pg/mL differentiated the mild regurgitation group from the moderate or severe regurgitation group. Our results correlating NT-proBNP and echocardiographic parameters indexed to body surface area indicate that these adult criteria can be used in children to grade mitral regurgitation and inform surgical decision-making.

Echocardiographic examination of mitral valve abnormalities in the paediatric population: current practices

We reviewed the recent literature for echocardiographic assessment of mitral valve abnormalities in children. A literature search was performed within the National Library of Medicine using the keywords "mitral regurgitation and/or stenosis, children." The search was refined by adding the keywords "echocardiographic definition, classification, and evaluation." Thirty-one studies were finally included. Significant advances in echocardiographic imaging of mitral valve defects, mainly due to the implementation of three-dimensional technology, contribute to a better understanding of the underlying anatomy. However, heterogeneity between classification systems of mitral valve disease severity is a serious problem. For regurgitant lesions, there is only very limited evidence from small studies that support the adoption of quantitative/semi-quantitative indexes commonly employed in adults. Despite the lack of evidence base, qualitative evaluation of regurgitation severity is often employed. For stenotic lesions, no clear categorisation based on trans-valvular echocardiography-derived "gradients" has been consistently applied to define mild, moderate, or severe obstruction across different paediatric age ranges. Quantitative parameters such as valve area have also been poorly validated in children. Adult recommendations are frequently applied without validation for the paediatric age. In conclusion, significant advances in the anatomical evaluation of mitral valve diseases have been made, thanks to three-dimensional echocardiography; however, limitations remain in the quantitative/semi-quantitative estimation of disease severity, both with respect to valvular regurgitation and stenosis. Because adult echocardiographic recommendations should not be simply translated to the paediatric age, more specific paediatric guidelines and standards for the assessment of mitral valve diseases are needed.

A fast region-based active contour model for boundary detection of echocardiographic images

This paper presents the boundary detection of atrium and ventricle in echocardiographic images. In case of mitral regurgitation, atrium and ventricle may get dilated. To examine this, doctors draw the boundary manually. Here the aim of this paper is to evolve the automatic boundary detection for carrying out segmentation of echocardiography images. Active contour method is selected for this purpose. There is an enhancement of Chan-Vese paper on active contours without edges. Our algorithm is based on Chan-Vese paper active contours without edges, but it is much faster than Chan-Vese model. Here we have developed a method by which it is possible to detect much faster the echocardiographic boundaries. The method is based on the region information of an image. The region-based force provides a global segmentation with variational flow robust to noise. Implementation is based on level set theory so it easy to deal with topological changes. In this paper, Newton-Raphson method is used which makes possible the fast boundary detection.

Quantification of left to right shunt in patent ductus arteriosus by color Doppler

Ultrasound is a reliable tool to diagnose patent ductus arteriosus in premature infants but no reliable noninvasive method exists to quantify ductal flow. The aim of this study was to quantify the size of the shunt via persistent ductus arteriosus from pixel counts in color Doppler flow images. A cotton band was placed around the ductus arteriosus of newborn lambs to adjust the magnitude of flow. For flow measurements, ultrasonic transit time flow probes were applied around the ascending aorta and ductus arteriosus. Twenty-four different flow states were attained in four newborn lambs. An Acuson Sequoia scanner equipped with a 7 MHz transducer was used to register Doppler data and images with maximal color distribution during diastole in the pulmonary artery longitudinal sections (PALS). Each image-pixel was matched with the color velocity bar and the pixels were assigned to the corresponding flow velocity. The total area showing color relative to the area of the PALS correlated well with the amount of ductal flow (r = 0.87, r(2) = 0.75, p < 0.001). When Qp/Qs was >1.4:1, more than 40% of the area in PALS in diastole exhibited color information. Similarly, the color pixel velocities squared correlated with the size of the shunt. Quantification of the percentage of pixels in a color Doppler registration via a computer-based analysis shows a high correlation with the size of ductal shunting.

Discrepancy Between Intraoperative Transesophageal Echocardiography and Postoperative Transthoracic Echocardiography in Assessing Congenital Valve Surgery

BACKGROUND

The purpose of this study was to investigate the discrepancy between intraoperative transesophageal and postoperative transthoracic echocardiography in assessing residual regurgitation in children undergoing valve repair.

METHODS

Forty-two consecutive children (median age, 5.1 years) who underwent valve repair for valvar regurgitation from 2001 to 2004 were retrospectively analyzed. The patients were divided into two groups: atrioventricular valve group (n = 33) and aortic valve group (n = 9). Regurgitation grade, fractional shortening, and atrioventricular inflow velocity obtained by intraoperative transesophageal echocardiography were compared with those obtained by transthoracic echocardiography at discharge (median, 11 days) and at follow-up (median, 8 months).

RESULTS

Intraoperative transesophageal echocardiography revealed specific residual lesions in 4 patients, leading to successful re-repair. Fractional shortening obtained by intraoperative transesophageal echocardiography was lower than that obtained by predischarge transthoracic echocardiography (p < 0.01). In the atrioventricular valve group, the regurgitation grade obtained by intraoperative transesophageal echocardiography was lower than that obtained by predischarge transthoracic echocardiography (0.7 +/- 0.8 versus 1.4 +/- 0.9; p < 0.01), and agreement between the two examinations was found in 12 patients (38%). Peak atrioventricular inflow velocity obtained by intraoperative transesophageal echocardiography was lower than that obtained by predischarge transthoracic echocardiography (p < 0.01). In the aortic valve group, there was no significant difference between the regurgitation grades in the two examinations (0.8 +/- 0.8 versus 1.1 +/- 0.9), and complete agreement in regurgitation grade was found in 5 (56%) of 9 patients.

CONCLUSIONS

There were considerable discrepancies between the examinations in evaluation of residual atrioventricular valve regurgitation and potential atrioventricular valve stenosis: most of the residual regurgitations were underestimated by intraoperative transesophageal echocardiography. In contrast, reasonable agreement was found between the two examinations in evaluation of aortic valve regurgitation.

Acute geometric changes of the mitral annulus after coronary occlusion: a real-time 3D echocardiographic study

We performed real-time 3D echocardiography in sixteen sheep to compare acute geometric changes in the mitral annulus after left anterior descending coronary artery (LAD, n=8) ligation and those after left circumflex coronary artery (LCX, n=8) ligation. The mitral regurgitation (MR) was quantified by regurgitant volume (RV) using the proximal isovelocity surface area method. The mitral annulus was reconstructed through the hinge points of the annulus traced on 9 rotational apical planes (angle increment=20 degrees). Mitral annular area (MAA) and the ratio of antero-posterior (AP) to commissure-commissure (CC) dimension of the annulus were calculated. Non-planar angle (NPA) representing non-planarity of the annulus was measured. After LCX occlusion, there were significant increases of the MAA during both early and late systole (p<0.01) with significant MR (RV: 30+/-14 mL), while there was neither a significant increase of MAA, nor a significant MR (RV: 4+/-5 mL) after LAD occlusion. AP/CC ratio (p<0.01) and NPA (p<0.01) also significantly increased after LCX occlusion during both early and late systole. The mitral annulus was significantly enlarged in the antero-posterior direction with significant decrease of non-planarity compared to LAD occlusion immediately after LCX occlusion.

Quantification of mitral regurgitation by automated cardiac output measurement: experimental and clinical validation

OBJECTIVES

To develop and validate an automated noninvasive method to quantify mitral regurgitation.

BACKGROUND

Automated cardiac output measurement (ACM), which integrates digital color Doppler velocities in space and in time, has been validated for the left ventricular (LV) outflow tract but has not been tested for the LV inflow tract or to assess mitral regurgitation (MR).

METHODS

First, to validate ACM against a gold standard (ultrasonic flow meter), 8 dogs were studied at 40 different stages of cardiac output (CO). Second, to compare ACM to the LV outflow (ACMa) and inflow (ACMm) tracts, 50 normal volunteers without MR or aortic regurgitation (44+/-5 years, 31 male) were studied. Third, to compare ACM with the standard pulsed Doppler-two-dimensional echocardiographic (PD-2D) method for quantification of MR, 51 patients (61+/-14 years, 30 male) with MR were studied.

RESULTS

In the canine studies, CO by ACM (1.32+/-0.3 liter/min, y) and flow meter (1.35+/-0.3 liter/min, x) showed good correlation (r=0.95, y=0.89x+0.11) and agreement (deltaCO(y-x)=0.03+/-0.08 [mean+/-SD] liter/min). In the normal subjects, CO measured by ACMm agreed with CO by ACMa (r=0.90, p < 0.0001, deltaCO=-0.09+/-0.42 liter/min), PD (r=0.87, p < 0.0001, deltaCO=0.12+/-0.49 liter/min) and 2D (r=0.84, p < 0.0001, deltaCO=-0.16+/-0.48 liter/min). In the patients, mitral regurgitant volume (MRV) by ACMm-ACMa agreed with PD-2D (r= 0.88, y=0.88x+6.6, p < 0.0001, deltaMRV=2.68+/-9.7 ml).

CONCLUSIONS

We determined that ACM is a feasible new method for quantifying LV outflow and inflow volume to measure MRV and that ACM automatically performs calculations that are equivalent to more time-consuming Doppler and 2D measurements. Additionally, ACM should improve MR quantification in routine clinical practice.