Echocardiography Foreshortening

The Big Heart Disease Lie

Reverse Heart Disease Today

Get Instant Access

Left Ventricle LVIDd

Fig. 3. Two-dimensional-guided M-mode measurements and derived indices. M-mode is simple, reproducible, and accurate when ventricular geometry is normal. It provides good endocardial resolution. The ejection fraction (EF, Teich) is an automated calculation based on the Teichholz method (see Table 4).

Fig. 3. Two-dimensional-guided M-mode measurements and derived indices. M-mode is simple, reproducible, and accurate when ventricular geometry is normal. It provides good endocardial resolution. The ejection fraction (EF, Teich) is an automated calculation based on the Teichholz method (see Table 4).

Diameter 1

Diameter 1

Biplane Ellipsoid Echo

Fig. 4. Prolate ellipsoid. One geometric model used to calculate left ventricular volumes from on M-mode measurements assumes an elliposoid shape for the left ventricle. This model uses diameters (D) and length to calculate areas and volumes. A hemi-ellipsoid model is preferred in left ventricular volumetric and mass quantification using two-dimensional echocardiography (Figs. 13 and 15).

Fig. 4. Prolate ellipsoid. One geometric model used to calculate left ventricular volumes from on M-mode measurements assumes an elliposoid shape for the left ventricle. This model uses diameters (D) and length to calculate areas and volumes. A hemi-ellipsoid model is preferred in left ventricular volumetric and mass quantification using two-dimensional echocardiography (Figs. 13 and 15).

lv volumes and ef by m-mode

Estimates of LV volumes and EF by M-mode rely on geometrical assumptions of LV morphology. The simplest formula cubes the LVIDd. Another calculates volume using the formula for a prolate ellipsoid (Fig. 4). These measures become even more inaccurate when applied to dilated ventricles. The Teichholz method (Table 4) is commonly used to calculate ventricular volumes from M-mode measurements (from which EF can be calculated). However, this method is only recommended when ventricular geometry is relatively normal (see Chapter 3, Fig. 14D). Specifically, in patients with myocardial infarction involving the apex, M-mode measurements, which are obtained at the base of the heart, will underestimate ventricular size and overestimate ventricular function.

lv parameters by 2d echocardiography

2D echocardiography is the primary modality used for qualitative and quantitative assessment of ventricular systolic performance (Table 5). In postmyocardial infarction and heart failure patients, 2D echo has great utility in their management and risk stratification. An inverse relationship exists between cardiovascular morbidity, mortality, and LV systolic function—specifically LVEF. EF, however, is not the only predictor of survival in patients with advanced heart failure.

limitations of 2d assessment of lv systolic function

2D echocardiography is not a true tomographic technique (like cardiac computed tomography or cardiac magnetic resonance imaging). Off-axis measurements,

Table 5

Two-Dimensional Parameters in Left Ventricular Function

Qualitative/semi-quantitative parameters

Quantitative parameters

Global function: ventricular wall motion and thickening

RWM assessment

Visual estimation of ejection fraction

Longitudinal ventricular shortening

Mitral annular motion

Left ventricular wall dimensions:

Wall thickness Internal diameters: LVIDd, LVIDs

MWFS: from linear measures of diastolic and systolic cavity sizes and wall thickenesses:

Inner shell = ([LVIDd + SWTd/2 + PWTd/2 ]3 - LVIDd3 + LVIDs3) 1/3 - LVIDs

([LVIDd + SWTd/2 + PWTd/2] - [LVIDs + inner shell])

Left ventricular quantification

Biplane method of discs (modified Simpson's rule) Multiple diameter method Others based on assumptions for left ventricular geometry, e.g., cylinder-hemiellipse, biplane ellipsoid, hemisphere-cylinder, bullet, models

Left ventricular ejection fraction (%) = [(EDV - ESV)/EDV] x 100% Left ventricular mass (MassLV) = 0.8 x [1.04 (LVIDd + PWTd +

SWTd)3 - (LVIDd)3] + 0.6 g Left ventricular wall stress (a) Meridional wall stress Circumferential

Table modified from Recommendations for Chamber Quantification. American Society of Echocardiography, 2005. RWM, regional wall motion; LVIDd, left ventricular internal diameter at end diastole; LVIDs, left ventricular internal diameter at end systole; MWFS, mid-wall fractional shortening; SWTd, septal wall thickness; PWTd, posterior wall thickness; EDV, end diastolic volume; ESV, end systolic volume; FS, fractional shortening.

Table modified from Recommendations for Chamber Quantification. American Society of Echocardiography, 2005. RWM, regional wall motion; LVIDd, left ventricular internal diameter at end diastole; LVIDs, left ventricular internal diameter at end systole; MWFS, mid-wall fractional shortening; SWTd, septal wall thickness; PWTd, posterior wall thickness; EDV, end diastolic volume; ESV, end systolic volume; FS, fractional shortening.

Foreshorten Apex

Fig. 5. Left ventricular foreshortening. Foreshortening (shown right) occurs when the imaging plane does not transect the center of left ventricular apex (left). It is a common source of error in left ventricular quantification in two-dimensional echocardiography. (Please see companion DVD for corresponding video.)

Fig. 5. Left ventricular foreshortening. Foreshortening (shown right) occurs when the imaging plane does not transect the center of left ventricular apex (left). It is a common source of error in left ventricular quantification in two-dimensional echocardiography. (Please see companion DVD for corresponding video.)

e.g., foreshortening, easily occur (Fig. 5; please see companion DVD for corresponding video). Distortions of LV geometry seen in patients with ischemic heart disease pose challenges to 2D assessment (Figs. 1A,B and 6).

qualitative and semi-quantitative measures of lv systolic function

Making linear measurements of cardiac chamber dimensions by 2D echo follows the principles outlined

Was this article helpful?

0 0
Your Heart and Nutrition

Your Heart and Nutrition

Prevention is better than a cure. Learn how to cherish your heart by taking the necessary means to keep it pumping healthily and steadily through your life.

Get My Free Ebook


Responses

  • marcia maxwell
    How to calculate ejection fraction from echocardiogram lvidd & vids?
    7 years ago
  • Kris
    How reliable is 2D ?
    4 years ago

Post a comment