TABLE 4.1 • Maximum treadmill exercise provides highest workload with image acquired immediately after exercise; or • Supine bicycle exercise (allows continuous imaging). • Compare rest and stress cine loop images of the LV in standard views. • Normal wall motion at rest and a regional wall motion abnormality with stress indicates ischemia. • Abnormal regional wall motion at rest that persists with stress indicates prior infarction. • Dobutamine is infused beginning at low dose (5 or 10 μg/kg/min), increasing by 10 μg/kg/min every 3 minutes to a maximum dose of 40 μg/kg/min or target heart rate of 85% maximum predicted. • Atropine may also be used to achieve target heart rate. • Comparison of rest versus peak stress cine loop images of the LV in standard views. • Normal wall motion at rest and a regional wall motion abnormality with stress indicate ischemia. • Abnormal regional wall motion at rest that persists with stress indicates prior infarction. • Dobutamine is infused beginning at low dose (5 μg/kg/min) and increasing to 10 μg/kg/min. • The stress test may be continued to evaluate for ischemia as above. • Images of the LV in cine loop format at baseline and low-dose dobutamine (increase in contractility with no change in heart rate) are compared. • Viability is diagnosed when an area of hypokinesis or akinesis at rest shows improved wall motion at low-dose dobutamine. • If wall motion again worsens at higher dobutamine doses, ischemia also is present (the biphasic response to stress). • Use standard dobutamine stress echo protocol. • Compare rest versus peak stress cine loop images of the LV in standard views. • A new wall motion abnormality with stress is consistent with inducible ischemia. • Balanced ischemia (equal involvement of all major coronary arteries) or small-vessel disease may be missed on stress echocardiography. • Measure stroke volume and ejection fraction as dobutamine is increased from 0 to 20 μg/kg/min in 5 μg/kg/min increments. • Measure AS velocity, mean gradient, and valve area at each stress level. • Stop for symptoms or when a hemodynamic endpoint is reached. • Severe AS is present if aortic velocity increases to at least 4 m/s and valve area remains less than 1 cm2. • Failure of stroke volume or EF to increase by at least 20% is termed “lack of contractile reserve” and connotes a poor clinical outcome. • Measure TR jet velocity at baseline and at peak exercise stress on maximum treadmill testing or with supine bicycle exercise. • The transmitral pulsed or CW Doppler velocity curve also may be evaluated at rest and with exercise. • MR may be evaluated using CW and color Doppler (optional). • The primary goal is to assess peak PA pressure with exercise (and change from baseline), calculated from the TR jet velocity. • With MS, the transmitral velocity and mean gradient will increase as expected for the increase in flow rate; this measurement is rarely diagnostically useful. • With primary MR, severity may increase with exercise (e.g., with mitral prolapse), but quantitation at peak exercise is challenging. The change in PA pressure is a surrogate for the increase in regurgitation. • Supine bicycle stress is preferred for evaluation of HCM, because it allows data recording at each stress level. • LV outflow velocity is recorded with pulsed and CW Doppler at baseline and with stress. • MR also is evaluated with CW and color Doppler. • Latent LV outflow obstruction is present when the resting subaortic gradient is <30 mm Hg but increases to >30 mm Hg with stress. • Separating the LV outflow signal from the higher-velocity MR signal can be challenging in some cases. • Useful features in identifying the origin of the Doppler signal are timing of flow onset relative to the QRS signal, shape of the velocity curve, delineation of a smooth dark edge to the velocity curve, and recordings showing separate LV outflow and MR CW Doppler flow curves. TABLE 4.2 • Rapid acquisition, familiar image planes • Image can be rotated, helpful with complex cardiac anatomy • Shows anatomy in “surgical” views • Enlarged 3D image of structure of interest • High spatial resolution • High temporal resolution • Quantitation of LV volumes and ejection fraction • Provides 3D LV shape and dyssynchrony • Accurate measurements of cardiac dimensions • More objective and less operator-dependent than standard 2D imaging • Visualization of all myocardial segments simultaneously • Simultaneous images in two defined planes • Highest spatial resolution • Highest temporal resolution • Visualization of 3D geometry of vena contracta and proximal isovelocity surface area for regurgitant lesions • Location of paravalvular prosthetic leaks and intracardiac shunts TABLE 4.3 Summarized from Lang RM, Badano LP, Tsang W, et al: EAE/ASE recommendations for image acquisition and display using three-dimensional echocardiography. J Am Soc Echocardiogr 25(1):3-46, 2012.
Specialized Echocardiography Applications
Stress Echocardiography
Three-Dimensional Echocardiography
Image Acquisition and Display
Key Points
Examination Protocol
Clinical Indication
Stress Modality
Protocol
Interpretation
Detection or evaluation of coronary artery disease
Exercise
Pharmacologic
Myocardial viability
Dobutamine stress
Postcardiac transplant myocardial ischemia
Dobutamine stress
Low output aortic stenosis (AS)
Dobutamine stress
Mitral valve disease
Exercise stress
Table Continued
Clinical Indication
Stress Modality
Protocol
Interpretation
Hypertrophic cardiomyopathy (HCM)
Exercise stress
Advantages
Limitations
Real-time 3D mode—narrow section, volume-rendered images
Narrow sector; entire structure does not fit in imaging plane.
Real-time “zoom” volume-rendered cropped images
A wider field of view decreases spatial and temporal resolution.
Full-volume gated acquisition for volume-rendered cropped images
Full-volume gated acquisition for multiple 2D tomographic slices
Endocardial definition may be suboptimal depending on transducer position.
Simultaneous multiplane 2D imaging
Only two planes visualized.
3D color Doppler
Slow frame rate with low temporal resolution.
TTE Image Acquisition
TEE Image Acquisition
Sequence for TEE Full-Volume Image Orientation (see Fig. 4.7)
Aortic valve
PLAX with and without color, narrow angle and zoomed
Mitral valve
0-120° mid-esophageal with and without color, zoomed
LV
A4C, narrow and wide angle
0-120° mid-esophageal view including entire LV, full-volume
RV
A4C with image tilted to put RV in center of image
0-120° mid-esophageal view, tilted to put RV in center of image, full-volume
Atrial septum
A4C, narrow angle and zoomed
0° with probe rotated toward atrial septum, zoomed or full-volume
Pulmonic valve
RV outflow view with and without color, narrow angle and zoomed
Table Continued
TTE Image Acquisition
TEE Image Acquisition
Sequence for TEE Full-Volume Image Orientation (see Fig. 4.7)
Tricuspid valve
Quantitation From 3D Datasets
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Specialized Echocardiography Applications
4
The specific stress modality depends on the clinical diagnosis and type of information needed for decision making (Table 4.1).
May be difficult to optimize image quality for all structures in the field of view.
“Stitch” artifacts occur because of patient and respiratory motion.
60° mid-esophageal short-axis with and without color, zoomed or full-volume
120° mid-esophageal long-axis with and without color, zoomed or full-volume
2D views at 60° and 120° with aortic valve centered in acquisition boxes
Live 3D to optimize gain
Full-volume acquisition, and then rotated 90° clockwise around y-axis
PLAX with and without color, narrow angle and zoomed
A4C with and without color, narrow angle and zoomed
2D views at 90° and 120° with mitral valve centered in acquisition boxes
Full-volume acquisition, rotated 90° counterclockwise around x-axis and then 90° counterclockwise in plane so that aortic valve is superior
Full-volume acquisition for quantitation of LV volumes, ejection fraction, and regional wall motion
Data displayed as a moving 3D surface-rendered image with color coding and as a time graph
90° high-esophageal view with and without color, zoomed
120° mid-esophageal three-chamber view with and without color, zoomed
2D high-esophageal view at 0° with pulmonic valve centered in acquisition box
Full-volume acquisition, rotated 90° counterclockwise around x-axis, then rotate in plane 180° counterclockwise so that anterior leaflet is superior
A4C with and without color, narrow angle and zoomed
RV inflow view with and without color, narrow angle and zoomed
0-30°mid-esophageal four-chamber view with and without color, zoomed
40° transgastric view with anteflexion with or without color, zoomed
TTE∗ 2D views in off-axis A4C view with tricuspid valve centered in acquisition boxes
Full-volume acquisition, rotated 90° counterclockwise around x-axis and then rotate 45° in plane so that septal leaflet is in 6 o’clock position