1 The Pediatric Transthoracic Echocardiogram
Imaging Planes
Key Points
• Imaging planes may be unique to each individual patient; for example, in the setting of a newborn with a diaphragmatic hernia, the typical views may be obtained from nonstandard locations on the chest because the heart is displaced significantly within the thoracic cavity.
• Best practice is to obtain two-dimensional (2D) imaging before spectral or color flow Doppler. This allows for an anatomic frame of reference before the addition of physiologic data.
• Before acquisition of Doppler data, an anatomic 2D image should be recorded to document the curser position.
• Ergonomics should be considered at all times (Figs. 1-1 and 1-2). Make yourself comfortable. Based on patient age, location where study is being performed, and other environmental conditions (i.e., patient instrumentation, patient body position restrictions, lighting conditions), accommodations may be required to optimize image acquisition. This can make the difference between an exam that shows the pathology at a quality level, which allows for an accurate diagnosis, and a study that is incomplete, requiring subsequent imaging or resulting in incorrect management decisions.
• Standard adult imaging planes and views apply. However, variations of these views are required to optimally image atypical anatomy and cardiac position.
• Nonstandard views are frequently used to assess complex anatomy and track the route of extracardiac anatomic structures and vessels that cannot be seen in a single view. For example, a right ventricle (RV)-to-pulmonary artery (PA) conduit may require evaluation in three separate imaging planes to obtain a complete assessment: parasternal to visualize the mid-conduit, apical to image the conduit origin, and subcostal to image the distal end at the pulmonary branch bifurcation.
• With the use of nonstandard views, it is critical to acquire confirmatory points of reference, to obtain longer clips, and to demonstrate anatomic relationships via sweeps from one plane to the next. This will allow the interpreting physician the opportunity to render the most accurate diagnosis.
• Use annotation on the clip to communicate findings and relay information as to the intent of clip acquisition (Table 1-1, Figs. 1-3 to 1-10).
| Window | View | Basic Anatomy Viewed |
|---|---|---|
| Left parasternal | LV long axis | LV |
| Slice 2 in Figure 1-3 | Ventricular septum | |
| MV (and supporting structures) | ||
| AV | ||
| LA | ||
| CS | ||
| Proximal aortic root | ||
| RV inflow | RV | |
| Slice 1 in Figure 1-3 | TV (and supporting structures) | |
| RA | ||
| RV outflow | RVOT | |
| Slice 3 in Figure 1-3 | Pulmonary valve | |
| Proximal main PA | ||
| Short axis | LV | |
| Slices 1, 2, and 3 in Figure 1-4 | MV (and papillary muscles) | |
| AV | ||
| Ventricular septum | ||
| Coronary artery origins | ||
| RVOT | ||
| Pulmonary valve | ||
| Main PA and branches | ||
| TV | ||
| AS | ||
| PVs | ||
| LPA/ductal | ||
| Apical | 4C | LV, RV |
| Figure 1-5 | VS | |
| AS | ||
| AVVs | ||
| Cardiac crux | ||
| LA, RA | ||
| RV moderator band | ||
| Pulmonary venous flow/connection | ||
| Slice 3 in Figure 1-3 | CS | |
| “Five” chamber Slice 1 in Figure 1-5 |
LVOT | |
| Further anterior angulation | RVOT, pulmonary valve | |
| 3C Figure 1-6 |
All structures noted in parasternal long axis views | |
| Subcostal | 4C | LV, RV |
| Figure 1-7 | VS | |
| AS | ||
| Left and right ventricular AVVs | ||
| LVOT, RVOT | ||
| Short axis | VS | |
| Figure 1-8 | RVOT | |
| AS | ||
| IVC | ||
| SVC | ||
| Right parasternal | Long axis | SVC |
| Azygous vein | ||
| Superior aspect of AS | ||
| Ascending aorta | ||
| RPA | ||
| RCA | ||
| Short axis | Ascending aorta | |
| RPA | ||
| PPV | ||
| Suprasternal notch | Long axis | Aortic arch |
| Figure 1-9 | Head and neck vessel branching | |
| Innominate vein | ||
| RPA | ||
| Short axis | Ascending aorta | |
| Figure 1-10 | Arch sidedness | |
| PV crab view | ||
| Additional branch PA views |
Figure 1-6 Apical three-chamber (3C) view, 90-degree counterclockwise rotation from the apical 4C view.
(Adapted from Snider RA, Serwer GA, Ritter SB. Echocardiography in Pediatric Heart Disease. St. Louis: Mosby; 1980.)
Transducers
• Whenever possible, the highest frequency transducer should be used. A higher frequency can provide better resolution, thus increasing accuracy in identifying smaller or more closely spaced structures.
• When performing pediatric echocardiography (echo), it is vital to have access to multiple transducers. Patient size and body habitus can vary widely, from the extremely premature infant weighing as little as 500 g to the adolescent weighing more than 100 kg. For each of these patients, numerous transducers may be required during the performance of a single study. It is typical for a 10- to 12-MHz transducer to be used for newborns, and a 1- to 3-MHz transducer to be used for the largest of patients.
• The same machine gain settings for image optimization apply as in all aspects of echo. However, adjustment in the Nyquist limit settings is common. For turbulent pathologic lesions (high cardiac output states, valve stenosis or regurgitation, a shunting lesion), the Nyquist limit is adjusted upward to avoid background noise. On the other hand, when assessing low-velocity flow (e.g., flow through pulmonary veins [PVs] or coronary arteries), the Nyquist limit settings are adjusted downward to enhance the opportunity to identify flow in these structures.
• New technologies continue to improve transducer quality, allowing for more versatility. A single transducer can now image in a wide array of imaging frequencies that can be changed easily on the machine’s control panel.
• When appropriate, a lower frequency can be used to improve both color and spectral Doppler sensitivity. Keep in mind that this can result in degradation in 2D image quality. As a general rule, lower frequencies have better Doppler signals.
• New imaging modalities such as tissue Doppler imaging, harmonic imaging, and velocity vector imaging can also determine transducer selection. These features are being incorporated more and more as research is confirming their usefulness (Figs. 1-11 and 1-12).
Protocols
• Exam protocols should be followed to ensure that all structures are demonstrated and no important detail is overlooked.
• A protocol should not only include the sequence of views but also include all expected measurement locations and methods of obtaining those measurements.
• In some labs, the sonographer will create a preliminary report, and this can be a part of the overall lab protocol. This postprocedure component of the lab protocol serves to further refine expectations and enhances the sonographer-physician relationship.
Sample Pediatric Protocol for a New Patient (Derived from Seattle Children’s Hospital Protocol)
• Remember that a narrow sector creates better resolution, with both 2D and color. Be careful not to lose your frame of reference when using a narrow sector in 2D. All structures should be assessed by 2D imaging first; do not be too quick to put the color on!
• When acquiring any type of Doppler information, it is important to be as parallel as possible to flow to measure maximal velocity. It is important, especially with pathology, to perform Doppler imaging from multiple windows to ensure measurement of the maximal velocity. Always acquire a clip demonstrating your cursor placement before displaying spectral Doppler or M-mode tracings.
Parasternal Long Axis View
• 2D left ventricular long axis view. Demonstrate valve and ventricular function. Examine the coronary sinus (CS) for dilation. Focus on the mitral valve (MV) and aortic valve (AV) (separately); use zoom function if appropriate. Measure aortic annulus, sinus, and sinotubular junction in systole.
• Color Doppler of the MV and AV (separately, without zoom). Be sure to clip sweeps of the valves to evaluate for any anatomic abnormalities or eccentric regurgitation.
• Use color Doppler to evaluate the interventricular septum for any defects. Be sure to sweep all the way posterior and anterior. This may require multiple clips and may also require adjusting the Nyquist limit and gain.
• 2D image of the right ventricular inflow: evaluate tricuspid valve (TV) and right ventricular function.
Parasternal Short Axis View
• Obtain M-mode of the right ventricular wall/RV/interventricular septum/left ventricle (LV)/left ventricular posterior wall (measure right ventricular wall and RV at end-diastole; interventricular septum/LV/left ventricular posterior wall measurements done in diastole and systole). M-mode should be performed at the MV leaflet tips (between the tip of the papillary muscle and the leaflet tips; M-mode will show just a little bit of the leaflet). Record image of M-mode with measurements to show where measurements were made.
• Zoom up on the aortic valve. 2D imaging to evaluate number and function of leaflets. Evaluate coronary artery origins by 2D and color Doppler (will need to turn Nyquist limit down to 30s or even 20s; keep color box small). Screen for an abnormal coronary vessel coursing between the aorta and PA.
• 2D sweep from the AV to the left ventricular apex. Be sure to have a good look at the MV structure (evaluate for cleft and papillary muscle structure).
• Color Doppler: Clip with color on the AV and a separate clip of color on the MV. Color sweep along both sides of the interventricular septum, from the AV to the left ventricular apex (may have to slide down an interspace to image the apical aspect). This may take multiple clips to view the entire septum.
• Color Doppler imaging across the tricuspid valve. PW Doppler/CW Doppler ultrasound of TR, if applicable.
• 2D imaging of the RVOT/pulmonary valve/main pulmonary artery/pulmonary artery branches. Zoom in on the pulmonary valve and measure the annulus.
• Color Doppler imaging from the RVOT through the branches (use a long, narrow sector). PW Doppler ultrasound of the RVOT, pulmonary valve, main pulmonary artery (if applicable), and right and left pulmonary branches. CW Doppler ultrasound across the pulmonary valve/main pulmonary artery. Evaluate for a PDA.
High Left Parasternal View
• Visualize the right PA, left PA, and descending aorta. If a duct is present, you should be able to see a third “finger” or “prong.”
Four-Chamber Apical View
• 2D clip to evaluate function. Clip showing sweeps all the way anterior and all the way posterior to evaluate the CS (may need to do two separate clips).
• Color Doppler on the TV (be sure to sweep through the entire valve). PW Doppler to evaluate TV inflow. CW Doppler to detect any TR, and measure peak velocity.
• Color Doppler on left heart (right PV, left lower PV, and MV). Evaluate PW Doppler pattern in the right PV. PW Doppler the MV inflow, measure the time interval from MV closure to MV opening for use in Tei index calculation. CW Doppler regurgitation if applicable.
• Tissue Doppler imaging of the septal and lateral MV annulus. Measure peak systolic velocity, peak E′ (early diastolic tissue Doppler velocity), and peak A′ (diastolic tissue Doppler velocity with atrial contraction). Tissue Doppler imaging of the lateral tricuspid annulus.
Apical Three-Chamber or Long Axis View
Subcostal Images
Abdominal Views (Uninverted)
• 2D clip demonstrating abdominal situs. Identify the inferior vena cava (IVC) (within liver) and aorta in cross section. Ensure that there is no dilated azygous vein (posterior to the liver and adjacent to the vertebral body).
• 2D sweep demonstrating cardiac position and IVC connection to the right atrium (RA). If clinically of concern, evaluate hemidiaphragm motion.
Subcostal Long or Four-Chamber View(Inverted Imaging)
• 2D clips demonstrating all four chambers. This should include sweeps that go from the diaphragm through the RVOT.
Subcostal Short Axis View
• Acquire 2D images, sweeping from the bicaval view to the apex. A true short axis view of the ventricle can be obtained by rotating clockwise. This is particularly important when evaluating a common AVV.
Subcostal Right Ventricular Inflow/Outflow View
• Rotate counterclockwise from the four-chamber (4C) view and angle anteriorly and toward the right shoulder to obtain a RVOT view.
Suprasternal Notch View
• 2D long axis view of the aortic arch (want to see all three head and neck vessels if at all possible). Color Doppler of the aortic arch. PW Doppler proximal and distal to the isthmus, and CW Doppler through the descending aorta.
• 2D sweep over to the SVC (demonstrating innominate vein connection, if possible). Color and PW Doppler of the SVC, either from this view or from the short axis view.
• Color sweep to the left to make sure that there is not a left SVC or left vertical vein (may need to turn Nyquist limit down and/or gain up).
• 2D short axis sweep demonstrating arch sidedness. Starting position should show aorta in cross section, innominate vein. Sweep superiorly to identify the first branch of the aorta, then follow the first branch to determine whether it branches.
• Color Doppler sweep demonstrating branching pattern and vessel pulsatility, starting from the short axis view. Because you are visualizing the innominate artery branching into a subclavian and common carotid artery all in a short axis, turn down the Nyquist limit so that these vessels will fill. CF Doppler and PW Doppler of the SVC if not done from the long axis view.
Right Parasternal
• These views should be used if subcostal views are suboptimal, particularly if you are unable to rule out a sinus venosus ASD from a subcostal bicaval view.
1 Lai WW, Mertens LL, Cohen MS, Geva T, editors. Echocardiography in Pediatric and Congenital Heart Disease: From Fetus to Adult. Oxford, UK: Wiley-Blackwell, 2009.
2 Snider AR, Serwer GA, Ritter SB. Echocardiography in Pediatric Heart Disease, 2nd ed. Philadelphia: Mosby-Year Book; 1997.
3 Silverman NH. Pediatric Echocardiography. Baltimore, MD: Williams & Wilkins; 1993.
4 Seward JB, Tajik AJ, Edwards WD, Hagler DJ. Two-Dimensional Echocardiographic Atlas. Volume I: Congenital Heart Disease. New York: Springer; 1987.
5 Otto C. The Practice of Clinical Echocardiography, 3rd ed. Philadelphia: Saunders Elsevier; 2007.
6 Otto C, Schwaegler RG, editors. Echocardiography Review Guide. Philadelphia: Saunders/Elsevier, 2008.
