Left and Right Ventricular Systolic Function

Left Ventricular Systolic Function

Step 1: Measure Left Ventricular Size

Left Ventricular Chamber Dimensions

▪ Two-dimensional (2D) measurement of left ventricular (LV) minor axis internal dimensions or 2D guided M-mode measurement of LV minor axis internal dimensions at end-diastole and end-systole

Key Points

□ LV internal dimensions are measured from the parasternal window, because the ultrasound beam is perpendicular to the blood-myocardial interface, providing high axial resolution (Fig. 6.1).
□ The parasternal long-axis view allows verification that measurements are perpendicular to the long axis of the LV. An oblique angle may not be recognized in short-axis views.
□ 2D imaging in long- and short-axis views is used to ensure the dimension is measured in the minor axis of the ventricle, and not at an oblique angle, which would overestimate size (Fig. 6.2).
□ The rapid sampling rate of M-mode (compared with the slow frame rate of 2D imaging) provides more accurate identification of the endocardial borders (Fig. 6.3).
□ End-diastole measurements are made at the onset of the QRS complex; end-systole measurements are made at the minimum chamber size, just before aortic valve closure.
□ Measurements are made from the leading edge of the septal endocardial to the leading edge of the posterior LV wall.
□ The posterior LV wall is identified on M-mode as the steepest, most continuous line. Identification of the endocardial border on 2D images is less reliable.
□ Measurements of LV internal dimensions and wall thickness are made at the level of the mitral valve chords just apical to the mitral leaflet tips.

2D and 3D Left Ventricular Chamber Volumes

▪ LV volumes are more accurate measures of chamber size than linear dimensions; three-dimensional (3D) measured LV volumes are more accurate than 2D calculations of volume. (Table 6.1)
▪ 2D echo measures of LV volumes are based on tracing endocardial borders in apical 4-chamber and 2-chamber views at end-diastole and end-systole, with volumes calculated using the biplane method of disks (Fig. 6.4).
▪ 3D LV volumes are calculated using semiautomated endocardial border tracing with a full 3D reconstruction of the LV at end-diastole and end-systole (Fig. 6.5). LV end-diastolic volume and end-systolic volume are indexed by dividing by body surface area (Table 6.2 and 6.3).

Key Points

□ Care is needed to obtain images from a true apical position; use of a steep left lateral decubitus position with an apical cutout in the stretcher allows optimal transducer positioning.
□ Depth is adjusted so the mitral annulus just fits on the image; gain and processing curves are adjusted to optimize endocardial definition.
Fig. 6.1 2D measurement of LV size.Parasternal long-axis view showing 2D measurement of LV internal dimension at end-diastole (onset of the QRS) from the septal endocardium to the posterior wall endocardium at the level of the mitral valve chords and myocardial thickness at end-diastole and end-systole. This minor axis dimension is measured perpendicular to the long axis of the LV. Ao, Aorta.
Fig. 6.2 Oblique LV dimension measurements.Parasternal long-axis view (left) showing that a line oriented to match the M-mode measurement of LV dimensions from this transducer position along the dotted line, would overestimate ventricular size, because the sample line is oblique compared to the correct minor axis dimension, shown on the right. Ao, Aorta.
□ Left-sided echo contrast enhances recognition of endocardial borders when image quality is poor.
□ End-diastolic tracings are made at the onset of the QRS (first frame on digital cine loop); end-systole is defined as minimal LV volume and is identified visually by frame-by-frame viewing of the images (Fig. 6.6).
□ Volumes are more reflective of the degree of LV dilation than linear dimensions.
□ The most common limitation of this approach is a foreshortened apical view, resulting in underestimation of ventricular volumes; 3D imaging helps avoid underestimation of LV volumes (Fig. 6.7).
Fig. 6.3 M-mode LV dimensions.When the M-mode bean can be aligned perpendicular to the long axis of the LV, based on 2D long- and short-axis views, the advantage of the M-mode recording is a high temporal sampling rate. The rapid motion of the septal and posterior wall endocardium allows precise measurements. The endocardium (arrow) typically is the most continuous line with the steepest slope in systole. Measurement of the end-systolic wall thickness and internal dimension (maximal posterior motion of the septum, or minimal LV dimension) is shown by the horizontal lines.

TABLE 6.1

2D and 3D Echocardiographic Measurement of LV Volumes and Ejection Fraction
	2D	3D
Window	Apical • Patient in steep left lateral position • Apical cutout in exam stretcher • Avoid apical foreshortening	Apical • Patient in steep left lateral position • Apical cutout in exam stretcher • Adjust transducer position to ensure inclusion of entire LV
Image acquisition	4-chamber and 2-chamber views • Adjust depth to mitral annulus level. • Adjust gain, time-gain compensation, harmonic imaging, and other instrument parameters to optimize endocardial definition. • Left-sided contrast enhances endocardial border identification when image quality is suboptimal.	Apical volumetric acquisition • Full-volume gated acquisition • Use 2D images for initial positioning and adjusting gain. • Use split screen display of orthogonal views to optimize acquisition. • Breath hold during acquisition to minimize stitch artifacts. • Left-sided contrast enhances endocardial border identification when image quality is suboptimal.
Endocardial borders	Manual tracing at end-diastole and end-systole • End-diastole defined as onset of QRS • End-systole defined as minimal LV volume Trace borders at time of image acquisition and adjust, if needed, on final review.	Semiautomated endocardial border detection • Exclude papillary muscles and trabeculations from LV chamber. • Review and adjust borders after acquisition.
Volume calculations	• Apical biplane formula	• Surface rendered LV volumes

Fig. 6.4 2D LV volumes.LV volumes and ejection fraction (EF) are calculated based on tracing endocardial borders at end-diastole (A and C) and end-systole (B and D) in both apical 4-chamber (A and B) and apical 2-chamber views (C and D). Identification of endocardial borders is optimized by playing the cine loop to show endocardial motion.
□ Body surface area may not be the ideal measure but is widely used clinically to index volumes for body size.

Left Ventricular Wall Thickness and Mass

▪ 2D or 2D-guided M-mode measurement of LV septal and posterior wall thickness at end-diastole are usually are sufficient for clinical care.
▪ LV mass and wall stress can be calculated from 2D images, if needed.

Key Points

□ LV wall thickness is measured from the parasternal window, because the ultrasound beam is perpendicular to the blood-myocardial interface, providing high axial resolution.
□ The rapid sampling rate of M-mode (compared with the slow frame rate of 2D imaging) provides more accurate identification of the endocardial borders.
□ Wall thickness of both the septum and posterior wall is measured at the level of the mitral valve chordae at end-diastole.
□ The septal wall thickness measurement does not include trabeculations on the right ventricular (RV) side of the septum and does not mistake the midseptal stripe for the right-sided endocardium.
□ The posterior LV wall thickness is measured from the endocardium to the posterior epicardium.
□ LV mass is calculated from endocardial and epicardial border tracing in a short-axis view at the papillary muscle level and measurement of LV length.

Step 2: Evaluate Left Ventricular Systolic Performance

2D and 3D Ejection Fraction

▪ LV ejection fraction is an essential part of the echo examination and should be measured by 2D or 3D methods whenever possible.
▪ LV ejection fraction is measured from 2D images using the apical biplane method with tracing of endocardial borders at end-diastole and end-systole in apical 4- and 2-chamber views (see Figs. 6.6 and 6.7). However, 3D measurement of LV ejection fraction is recommended when possible.
▪ If the ejection fraction cannot be measured due to poor endocardial definition, a visual estimate may be reported.

Key Points

□ LV ejection fraction (EF) is calculated from end-diastolic volume (EDV) and end-systolic volume (ESV) as:

EF = [ ( EDV − ESV ) / ED ] × 100

(6.1)

□ When image quality is suboptimal, left-sided contrast may enhance identification of endocardial borders (Fig. 6.8).
□ When quantitation of ejection fraction is not needed or is limited by image quality, LV ejection fraction is visually estimated based on parasternal short axis and apical 4-chamber, 2-chamber, and long-axis views.

TABLE 6.2

Reference Values for Echocardiographic Chamber Quantification
Chamber	Measurement	Normal Range (Women)	Normal Range (Men)	Units
Left Ventricle
	Diastolic diameter	3.8-5.2	4.2-5.8	cm
	Systolic diameter	2.2-3.5	2.5-4.0	cm
	2D diastolic volume	46-106	62-150	mL
	(indexed to BSA)	29-61	34-74	mL/m ²
	2D systolic volume	14-42	21-61	mL
	(indexed to BSA)	8-24	11-31	mL/m ²
	Ejection fraction	54-74	52-72	%
	Septal wall thickness	0.6-0.9	0.6-1.0	cm
	Posterior wall thickness	0.6-0.9	0.6-1.0	cm
	LV mass (2D method)	66-150	96-200	g
	(indexed to BSA)	44-88	50-102	g/m ²
	Relative wall thickness	0.22-0.42	0.24-0.42
Left Atrium
	AP diameter	2.7-3.8	3.0-4.0	cm
	(indexed to BSA)	1.5–2.3	1.5–2.3	cm/m ²
	LA volume	22-52	18-52	mL
	(indexed to BSA)	16–34	16–34	mL/m ²
Right Atrium
	RA major dimension	1.9-3.1	1.8-3.0	cm
	RA minor dimension	1.3-2.5	1.3-2.5	cm
	2D echo RA volume	9-33	11-39	mL/m²
Right Ventricle		Normal Range (Women and Men)
	RV basal diameter	2.5-4.1		cm
	RV subcostal wall thickness	1.1-0.5		cm
	RVOT proximal diameter	2.1-3.5		cm
	RVOT distal diameter	1.7-2.7		cm
	Fractional area change	35-63		%
	Tricuspid annular excursion (TAPSE)	1.7-3.1		cm

Data from Lang RM, Badano LP, Mor-Avi V, et al: 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 28(1):1-39.e14, 2015.

TABLE 6.3

Normal Ranges and Severity Partition Cutoff Values for 2D E-Derived LV Ejection Fraction and LA Volume
	Male				Female
	Normal Range	Mildly Abnormal	Moderately Abnormal	Severely Abnormal	Normal Range	Mildly Abnormal	Moderately Abnormal	Severely Abnormal
LV EF (%)	52-72	41-51	30-40	<30	54-74	41-53	30-40	<30
Maximum LA volume/BSA (mL/m²)	16-34	35-41	42-48	>48	16-34	35-41	42-48	>48

From Lang RM, Badano LP, Mor-Avi V, et al: 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 28(1):1-39.e14, Table 4, 2015.

□ A visual estimate is reported using a descriptive scale as follows:
- □ Normal (EF ≥55%)
- □ Mildly reduced (EF 45% to 54%)
- □ Moderately reduced (EF 30% to 44%)
- □ Severely reduced (EF <30%)

Stroke Volume and Cardiac Output

▪ Stroke volume calculations are increasingly routine, particularly when ventricular function is abnormal and when valve stenosis, valve regurgitation, or an intracardiac shunt is present.
▪ Stroke volume (SV in cm³ or mL) is the product of the cross-sectional area (CSA) of flow (in cm²) multiplied by the velocity-time integral (VTI in cm) of flow at that site (Fig. 6.9):

SV = CSA × VTI

(6.2)

▪ Stroke volume can be calculated at any site where diameter and velocity can be measured but most often is measured in the LV outflow tract (LVOT), just proximal to the aortic valve.
▪ Cardiac output (CO in L/min) is stroke volume (mL) times heart rate (beats/min), divided by 1000 mL/L:

CO = [ SV ( mL ) × heart rate ( beats / m in ) ] / 1000 mL / L = L / min

(6.3)

Key Points

□ LVOT diameter (D) is measured from a parasternal long-axis view in mid-systole, from inner edge to inner edge, immediately adjacent to the base of the aortic valve leaflets (Fig. 6.10A).
□ CSA is calculated as the area of a circle:

CSA = π ( radius ) 2 = 3.14 ( D / 2 ) 2

(6.4)

□ LV outflow velocity is recorded using pulsed Doppler, with a 2- to 3-mm sample volume length, from the apical window with the sample volume just proximal to the aortic valve (see Fig. 6.10B).
Fig. 6.7 Apical foreshortening.When the transducer is on the true apex of the LV, the chamber is ellipsoid (left) compared with a foreshortened view (right) where the ventricle appears more spherical with a false apex. LV volumes will be underestimated in a foreshortened view, and apical wall motion abnormalities may be missed. This potential error is avoided by moving the transducer down an interspace and laterally to the true apex.
Fig. 6.8 Contrast enhancement.When endocardial borders are poorly seen (left), left-sided contrast (right) improves visualization of the LV chamber and allows more accurate measurement of LV volumes.
Fig. 6.9 Doppler stroke volume (SV) calculation.The cross-sectional area (CSA) of flow is calculated as a circle based on a 2D echo diameter (D) measurement. The length of the cylinder of blood ejected through this CSA on a single beat is the velocity-time integral (VTI) of the Doppler curve. Stroke volume (SV) then is calculated as CSA × VTI.
□ A visible aortic valve closing click on the Doppler tracing ensures correct sample volume placement.
□ The modal velocity (darkest part of the velocity curve) is traced to obtain the velocity time integral.
□ The velocity time integral represents the “stroke distance” or the length of the cylinder of blood ejected by the LV on each beat.
□ A similar approach can be used to calculate stroke volume across the mitral annulus or the pulmonic valve.
□ In adults, normal stroke volume is about 80 mL, and normal cardiac output is about 6 L/min.
□ Stroke volume and cardiac output are indexed to body surface area. A normal stroke volume index is >35 mL/m².

Global Longitudinal Strain

▪ Strain is a measure of myocardial shortening that reflects LV systolic performance (Fig. 6.11).
▪ Speckle tracking strain allows measurement of longitudinal strain in apical 4-chamber, 2-chamber, and long-axis views.
▪ Global longitudinal strain is measured from all three apical views and displayed as a color-coded chart, a graph of strain over the cardiac cycle and as a single negative number.

Key Points

□ Normal global longitudinal strain is about −20% with smaller negative numbers reflecting impaired ventricular function.
□ Strain is more sensitive than ejection fraction for detection of early myocardial dysfunction.
□ Strain is less dependent on loading conditions compared with ejection fraction.
□ Strain algorithms vary from system to system, so serial studies should use the same equipment and software.

Step 3: Assess Regional Ventricular Function

▪ Regional (or segmental) ventricular function is evaluated as detailed in Chapter 8.
▪ Wall motion and thickening for each myocardial segment is graded as normal, hypokinetic, akinetic, or dyskinetic.
▪ Any areas of thinning and increased echogenicity (consistent with scar) are noted (Fig. 6.12).
▪ Regional variation in strain also can be used to evaluate segmental wall function.

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Tags: Echocardiography Review Guide

Apr 23, 2020 | Posted by admin in CARDIOLOGY | Comments Off

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Thoracic Key

Fastest Thoracic Insight Engine

Left and Right Ventricular Systolic Function

Left and Right Ventricular Systolic Function

Left Ventricular Systolic Function

Step 1: Measure Left Ventricular Size

Left Ventricular Chamber Dimensions

2D and 3D Left Ventricular Chamber Volumes

Left Ventricular Wall Thickness and Mass

Step 2: Evaluate Left Ventricular Systolic Performance

2D and 3D Ejection Fraction

Stroke Volume and Cardiac Output

Global Longitudinal Strain

Step 3: Assess Regional Ventricular Function

Full access? Get Clinical Tree

Thoracic Key

Fastest Thoracic Insight Engine

Left and Right Ventricular Systolic Function

Left Ventricular Systolic Function

Step 1: Measure Left Ventricular Size

Left Ventricular Chamber Dimensions

Key Points

2D and 3D Left Ventricular Chamber Volumes

Key Points

Left Ventricular Wall Thickness and Mass

Key Points

Step 2: Evaluate Left Ventricular Systolic Performance

2D and 3D Ejection Fraction

Key Points

Stroke Volume and Cardiac Output

Key Points

Global Longitudinal Strain

Key Points

Step 3: Assess Regional Ventricular Function

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