Final Feigenbaum’s Echocardiography DIGITAL

Feigenbaum’s Echocardiography

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Feigenbaum’s Echocardiography

NORMAL VALUES FOR 2D ECHOCARDIOGRAPHIC PARAMETERS OF LV SIZE AND FUNCTION ACCORDING TO GENDER

Table 5.3

Male

Female

Mean é SD

Mean é SD

Parameter

2-SD Range

2-SD Range

LV internal dimension Diastolic dimension (mm) Systolic dimension (mm)

50.2 ± 4.1 32.4 ± 3.7

45.0 ± 3.6 28.2 ± 3.3

42.0–58.4 25.0–39.8

37.8–52.2 21.6–34.8

LV volumes (biplane) LVEDV (mL)

106 ± 22 41 ± 10

76 ± 15 28 ± 7

62–150 21–61

46–106 14–42

LFESV (mL)

LV volumes normalized by BSA LVEDV (mL/m 2 )

54 ± 10 21 ± 5 62 ± 5

45 ± 8 16 ± 4 64 ± 5

34–74 11–31 52–72

29–61

LVESV (mL/m 2 ) LVEF (biplane)

8–24

54–74

BSA, body surface area; EDV, end-diastolic volume; EF, ejection fraction; ESV, end-systolic volume; SD, standard deviation. Borrowed from Lang RM, Badano LP, Mor-Avi V. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echocardiogr 2015;28:1–39.

of ventricular volume. In clinical practice, the apical two-chamber view is o en imaged tangentially, and the volume derived from this view may underestimate the true le ventricular volume. Because of cardiac translational motion, tangential imaging (i.e., not through

the midline of the ventricle) is more common in systole. is results in an artifactually small systolic le ventricular cavity and may result in overestimation of ejection fraction. It is common to encounter minor degrees of o -axis imaging in the apical view in which tangentially located myocardium appears to ll in the apex because of beam width imaging. Visually evaluating the location of the true apical myocardium in real time, before tracing the bound- ary, and purposefully placing the boundary within the vague tan- gential echoes can reduce the magnitude of this problem. For determination of le ventricular volume, the endocardial border is traced with papillary muscles and trabeculae excluded from the cavity (Figs. 5.8 and 5.9). e well-recognized underesti- mation of le ventricular volume by echocardiography, compared to a standard such as cardiac magnetic resonance imaging, is in part due to failure to exclude trabeculae from the cavity tracing. If there is asymmetry of ventricular geometry or a systolic wall motion abnormality, a single-plane view will have reduced accuracy for the reasons previously alluded to. In this instance, averaging of volumes from multiple views or use of three-dimensional echocardiography will increase accuracy. Once the diastolic and systolic volumes have been determined, stroke volume can be calculated as the di erence between these two volumes. Assuming the absence of mitral or aortic insu ciency, for- ward cardiac output then equals the product of heart rate and stroke volume. Ejection fraction can be calculated from these volumes as: stroke volume ÷ end-diastolic volume. Because the di erence between the diastolic and systolic le ventricular volume represents the total volume pumped by the ventricle, it represents the sum of forward-going stroke volume plus the volume of mitral and aortic regurgitation, if present. Automated Edge Detection Most currently available instrumentations incorporate algorithms to automatically identify and track the endocardial border of the le ventricle. e precise methodology by which endocardial borders are tracked varies from manufacturer to manufacturer. e basic principle is that the acoustic boundary between the blood pool and tissue is identi ed and then tracked throughout the cardiac cycle (Fig. 5.10). e degree to which this is automated is highly variable and ranges from fully automated systems in which there is no user interaction, to systems in which multiple points of the ventricular contour are manually de ned, a er which the boundary between points is extrapolated. One of the more common techniques is to identify the apex of the le ventricle and then the lateral and medial mitral annulus a er which automatic detection algorithms identify

FIGURE 5.7. Schematic illustration of Simpson rule or the rule of disks for calculating left ventricular volume. In the upper panel, a schematized left ventricular volume has been sub- divided into 10 sections, each of which is presumed to represent a disk of equal diameter at its top and bottom margins. The volume of each disk is calculated as area × height where height is defined as the left ventricular length from apex to base divided by the number of disks. The total volume of the ventricle is calculated as the sum of each disk volume. The lower panel is an apical four-chamber view recorded in a normal individual in which this algorithm has been used to calculate left ventricular volume.

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