Final Feigenbaum’s Echocardiography DIGITAL

Chapter 5 Evaluation of Systolic Function of the Left Ventricle

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Chapter 5 Evaluation of Systolic Function of the Left Ventricle

volume and ejection fraction. Compared to two-dimensional imag- ing, three-dimensional imaging provides more accurate information regarding le ventricular volume when compared to a standard such as cardiac magnetic resonance imaging. e advantage of three- dimensional volumetric calculations appears greatest in irregularly shaped ventricles which do not conform to a predictable geometric shape. ree-dimensional datasets have been merged with a vari- ety of edge detection algorithms allowing semiautomatic extraction of a three-dimensional volume a er user identi cation of a limited number of points, or as a fully automatic analysis. is advancement has dramatically reduced the time required for derivation of accurate three-dimensional volumes (Figs. 5.14 and 5.15). As with automated algorithms for determination of le ventricular volume from two- dimensional echocardiography, manual adjustment of the automati- cally de ned ventricular border is commonly necessary. Once gener- ated, the three-dimensional volume can be further subdivided into a 16- or 17-segment model as done with two-dimensional echocardi- ography. A variety of sophisticated measures of global and regional ventricular functions can be extracted from the same three-dimen- sional volume (Figs. 5.16 and 5.17). e data that can be extracted is platform speci c but includes regional volume change in 16 or 17 seg- ments as well as parameters of volume change over time which have shown promise for evaluation of mechanical dyssynchrony. Numer- ous studies have demonstrated the superiority of three-dimensional echocardiography over two-dimensional echocardiography for deter- mination of le ventricular volumes when compared to a standard such as cardiac magnetic resonance imaging. While the accuracy and inter- and intraobserver reproducibility of le ventricular volumes derived from three-dimensional datasets exceeds that of two-dimen- sional imaging, the magnitude of improvement in accuracy is not always at a level likely to result in a change in clinical decisionmaking. Most studies have suggested that le ventricular volumes determined with real-time three-dimensional echocardiography underestimate both end-diastolic and end-systolic volume. As with two-dimensional imaging, this is apparently due to inclusion of le ventricular trabec- ulae and papillary muscles within the cavity and is a more prominent problem with less experienced operators. A er acquisition of the full-volume three-dimensional data- set customized two-dimensional imaging planes can be extracted. Commonly a semi-automated technique is used to extract an apical two- chamber and four-chamber view or a series of le ventricular

Evaluation of Systolic Function of the Left Ventricle

FIGURE 5.14. Stylized shell rendering of a normal left ventricle recorded using full-volume three-dimensional echocardiography. Note the calculated end-diastolic and end-systolic vol- umes as well as ejection fraction and stroke volume. In the accompanying video note the normal motion of all visualized 17 segments.

of methods. Acquisition methods include real-time three-dimen- sional full volumetric scanning and merging or “stitching” several three-dimensional subvolumes into a full-volume dataset. is data- set can be further analyzed with a number of techniques. Some state- of-the-art systems include an arti cial intelligence algorithm which matches the le ventricular contour to a “library” of previously identi- ed ventricular cavities of various sizes and geometries in an e ort to ensure that the automated boundary detection is providing informa- tion within the realm of previously identi ed ventricular cavities. is then provides a second approach for determination of ventricular

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FIGURE 5.15. Full-volume three-dimensional imaging recorded in a patient with a left bundle branch block and mildly reduced left ventricular ejection fraction. Volumes, stroke volume, and ejection fraction are at the upper right. At the upper left a stylized shell has been fitted to the anatomically defined left ventricular cavity. In this instance selective volumes for only the septal and lateral walls are being graphed. Note the heterogene- ity of volume reduction in the septal and lateral walls related to the left bundle branch block.

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