Summary

Importance of PoCUS:

PoCUS is essential for quick and accurate diagnosis. Cardiac ultrasound can help in the characterization of shock, hemodynamics, and respiratory failure in critically ill patients, leading to more targeted and timely interventions. 

 

Standard Cardiac Views:

The module covers techniques for obtaining each of the five standard cardiac windows: parasternal long axis (PLAX), parasternal short axis (PSAX), apical four chamber, subxiphoid four chamber, and IVC views. Each of these windows offers distinct clinical information and can be used for various clinical assessments, including left ventricular function, pericardial effusions, ventricular size comparison, and IVC assessment for fluid status. 

The following charts summarize the key information for each view,  in both cardiology and EM conventions:

Subxiphoid IVC View

Technique

• To obtain a view of the IVC, the probe is placed in the subxiphoid space similar to the subxiphoid cardiac view but with the ultrasound beam pointed deep towards the patient’s back. 

• To obtain a longitudinal view the probe indicator should be directed towards the patient’s head. The probe should be heeled or rocked towards the patient’s head so that both the hepatic veins draining into the IVC and the IVC draining into the right atrium are visualized (Figure 27).

• To obtain a transverse view the probe indicator is directed to the patient right in emergency convention and the patient’s left in cardiology convention. 

• Adjust the depth to ensure the full IVC is seen on the bottom of the screen. 

• Adjust gain to ensure that blood within the IVC appears black. 

 

Figure 26: IVC External Landmarking

 

Note: Emergency vs Cardiology convention

The subxiphoid IVC long axis view will vary in appearance on the screen whether you are using emergency or cardiology convention. With the probe marker directed to the patient’s head the images on screen will appear as mirror images of each other depending on whether your screen marker is on the left, as in emergency convention, or on the right as in cardiology convention. In the emergency convention the IVC can be seen draining into the heart on the left side of the screen, in cardiology convention this will appear on the right hand side.

The subxiphoid IVC transverse view will appear the same on the screen whether you are using emergency or cardiology convention. This is because both the probe markers and screen markers are oriented opposite, resulting in the same net image on screen 

Figure 27. IVC View Emergency Medicine Convention. 

Figure 28. IVC View Cardiology Convention. 

Tips: 

• This window can be challenging to obtain in patients with obesity, abdominal pain or lots of bowel gas as it uses the liver as an acoustic window to view the heart.  

• If able, having the patient bend their legs can help relax the abdominal wall. Asking the patient to take a deep breath in can also bring the diaphragm and heart towards the probe. 

• It is common to mistake the aorta for the IVC as they are parallel and in close proximity. To avoid this, the IVC should be tracked until it is seen entering the RA. Additionally, the aorta should be pulsatile, but sometimes aortic pulsations can transmit to the IVC. If in doubt, visualize both in the transverse plane or use color doppler to determine direction of blood flow. 

 

What Am I Looking At?

For the longitudinal view of the IVC, the image will display the liver, hepatic veins (draining into IVC), and the IVC as it drains into the right atrium (Figure 29).

If starting from an A/P or cross-sectional of IVC, both the IVC and the abdominal aorta will be seen anterior to a thoracic vertebral body. The abdominal aorta will be anterior and to the (patient’s) left of the vertebral body, while the IVC will be anterior and to the (patient’s) right of the vertebral body (Figure 30)

Figure 29: IVC View in the EM Convention 

 

Figure 30: Subxiphoid IVC transverse view, emergency medicine convention

Clinical Utility

This view allows the provider to assess size, distensibility or collapsibility of the IVC as well as to make comparison of the IVC and aorta diameter. 

Subxiphoid Four Chamber View

Technique

• In this view, the heart is imaged in a coronal plane but from a different angle than the apical four-chamber view (Fig 21).

• The probe should be held “overhand” with the hand on top of the probe.

• Place the probe in the subxiphoid space with the ultrasound beam pointing up towards the patient’s left scapula.   

• In emergency convention the probe marker is pointing towards the patient’s right (figure 22A) and in cardiology convention it is directed towards the left (Figure 22B).

• Depth should be adjusted to ensure visualization of the left ventricle and posterior pericardium 

• Gain should be adjusted so the myocardium appears grey and blood black. 

 

Figure 21: Anatomical coronal view of the heart from the SubXiphoid position

 

Figure 22. SubXiphoid External Landmarking EM vs Cardiology Convention 

 

Note: Emergency vs Cardiology convention

The subxiphoid four chamber view will appear the same on the screen whether you are using emergency or cardiology convention. This is because both the probe markers and screen markers are oriented opposite, resulting in the same net image on screen 

Figure 23: SubXiphoid View Cardiology Convention.      Figure 24: SubXiphoid View EM Convention. 

Scanning Tips: 

• This window can be challenging to obtain in patients with obesity, abdominal pain or lots of bowel gas as it uses the liver as an acoustic window to view the heart.  

• Try using lots of gel and exerting the minimal needed pressure, although sometimes significant pressure is needed. 

• If able, having the patient bend their legs can help relax the abdominal wall. Asking the patient to take a deep breathing in can also bring the diaphragm and heart towards the probe. 

• If struggling with bowel gas, try moving the probe inferiorly and to the patient’s right to get a window through the liver. 

• Fan the probe, flattening it out until the heart comes into view on the screen. 

What Am I Looking At?

In this view a coronal view of the heart is obtained. In the near field just below the probe often the acoustic window of the liver can be seen. Just deep to that is the diaphragm upon which the right ventricle lies. Deep to that the left ventricle can be seen. In this view the ventricles are on screen right and the atria are on screen left. 

Figure 25: Video of the SubXiphoid 4 chamber view

 

Clinical Utility

This view is the best view to appreciate pericardial effusions. As it is also a four chamber view it also allows for assessment of the left and right ventricular size and function. Importantly this may be the only view available in emergent situations such as ongoing CPR so as not to interfere with chest compressions. 

Apical Four Chamber View

Technique

• In this view the heart is imaged in a coronal plane (Figure 16) 

• To obtain an apical four-chamber (A4C) view, the probe is placed over the apex of the heart which is usually located in the vicinity of the left nipple (or inframammary line in females), in the 4th-5th intercostal space and the ultrasound beam directed towards the patient’s right shoulder. 

• In emergency convention the probe marker is pointing towards the patient’s right hip and in cardiology convention it is directed towards the left shoulder (Figure 17)

• Once you reach the apex of the heart, as indicated by the left ventricle decreasing in size, tilt the tail of the probe down towards the patient’s feet. 

• Depth should be adjusted to ensure visualization of the atria in the far field 

• Gain should be adjusted so the myocardium appears grey and blood black. 

• The ideal view should have the IVS centered on the screen and from the top to bottom on the screen, parallel to the ultrasound beam. 

 

Figure 16: Coronal view of the heart from the apical window 

 

Note: Emergency vs Cardiology convention 

The apical four chamber view will appear the same on the screen whether you are using emergency or cardiology convention. This is because both the probe markers and screen markers are oriented opposite, resulting in the same net image on screen 

Figure 17. External Landmarking for A4C View Emergency Medicine Convention (A) vs Cardiology Convention (B)

 

Scanning Tips: 

• This window can be challenging to obtain, especially in mechanically ventilated patients, use lots of gel and make small circular movements until the best window is obtained. 

• If struggling to find a window, lying the patient in the left lateral decubitus position will aid in pulling the heart against the chest wall and the lung away from it 

• An adequate view should have the apex in the near-field, the ventricles appearing elongated with a straight interventricular septum running vertically down the screen. 

• The position of the cardiac apex is highly variable. One method used to reliably obtain an adequate A4C is to begin with a high-quality PSAX and slide the transducer inferolaterally keeping the LV centered on the screen before tilting the face of the probe upwards to the right shoulder to view the heart in a coronal plane 

What Am I Looking At

In this view a coronal view of the heart is obtained. In the near field just below the probe the apex with the RV visualized below on screen left and the LV on screen right. Deep to the ventricles the mitral and tricuspid valves can be separating the ventricles from the atria which lie in the far-field. The intraventricular and atrial septums can be seen running vertically on the screen from the near to far field, dividing the right and left sides of the heart. 

Figure 18: A4C coronal view of the heart, illustrating the right and left atria (RA, LA), right and left ventricles (RV, LV), interventricular septum (IVS), interatrial septum (IAS), mitral valve (MV), and tricuspid valve (TV).

 

Figure 19: Apical Four Chamber View EM Convention 

 

Figure 20. Apical Four Chamber View Video Clip 

 

Clinical Utility

The apical four chamber view provides a wealth of information including global assessment of LV and RV function and size. It is the best view to compare ventricular sizes. This is another view in which pericardial effusions can be seen. The A4C view also allows two-dimensional evaluation of the tricuspid and mitral valves. 

Parasternal Short Axis View

Technique

• The easiest way to find the PSAX view is to optimize your PSLX view and while maintaining the probe position on the chest wall rotate your probe 90 degrees clockwise (for cardiology convention) (Figure 6) or counterclockwise (for radiology convention) (Figure 7).  

• The ultrasound probe should be placed immediately patient left of the sternum at at the level of the 3rd of 4th intercostal space 

• To obtain a cross-sectional view of the heart the probe marker is directed to the right hip in emergency convention or the left shoulder in cardiology convention (resulting in the same image on the screen) 

• Depth should be adjusted to ensure the posterior pericardium is visible in the far field 

• Gain should be adjusted so that the myocardium appears grey, and blood appears black 

• The probe should be adjusted using small movements of sliding, sweeping and rotation to optimize the view, ensuring the LV appears circular on screen and not oval or elongated. 

Figure 6. External Landmarking for parasternal short cardiology convention 

Figure 7. External Landmarking for parasternal short EM convention 

Note: Emergency vs Cardiology convention: 

The parasternal short axis view will appear the same on the screen whether you are using cardiology or emergency convention. This is because both the probe markers and screen markers are oriented opposite, resulting in the same net image on screen 

Figure 8: Parasternal Short View Cardiology Convention. 

 Figure 9: Parasternal Short View EM convention. 

Scanning Tips: 

• Sometimes it is necessary to slide the probe to different intercostal spaces to find the best window to view the heart, especially mechanically ventilated patients. If struggling, try each intercostal space starting from below the clavicle 

• If struggling to find a window, lying the patient in the left lateral decubitus position will aid in pulling the heart against the chest wall and the lung away from it 

• The easiest way to find the PSAX view is to optimize your PSLX view and while maintaining the probe position on the chest wall rotate your probe 90 degrees clockwise. 

• Caution is required to avoid probe sliding when rotating the probe from the PLAX to obtain the PSAX view and to rotate 90 degrees to prevent an oblique view. Two hands can be used for this technique; one to rotate the probe while the other hand secures the position of the probe on the patient’s chest 

What Am I Looking At?

In this view a cross section of the short axis of the heart is obtained. Most prominent is the circular LV, appearing as a donut in the middle of the screen. In the near field just below the probe the crescent-shaped right ventricle is visible, “hugging” the LV. The LV and RV are separated by the interventricular septum (Figure 10). 

Figure 10: Parasternal Short View Labeled

 

PSAX Imaging Planes

Different imaging planes are available from the PSAX.  Progressive sliding (angling if the window does not allow sliding) of the face of probe from the patient’s right shoulder toward the patient’s left hip will successively produce images from the base through the apex of the heart. Here we will focus on the fundamental images obtained from the PSAX, starting with structures most superiorly at the right shoulder and progressively lower to the left hip: 

​​Aortic valve level: The aortic valve will be seen as a “Mercedes Benz” sign as the three leaflets of the AV close to produce the three-pointed star associated with the car logo. An ideal view will also include the RA, TV, RV, atrial septum and LA. (Figure 11) 

Figure 11: Parasternal Short Aortic Valve Level

 

Mitral valve level: From the AV view, the ultrasound beam is tilted inferiorly until the mitral valve is visualized. The MV has been described as a “fish-mouth” with anterior and posterior mitral leaflets representing the upper and lower lip respectively (Figure 12). In this view, the RV, IVS, and LV are also visualized. (Figure 13) 

Figure 12: Parasternal Short Zoomed Mitral Valve

Figure 13: Parasternal Short Mitral Valve View Video with color in the cardiology convention

 

Mid-papillary level:  Further tilting of the ultrasound beam in an inferior direction will produce the mid-papillary image. The papillary muscles appear as slightly hyperechoic “knobs” protruding from the inferior aspect of the LV. The posteromedial papillary muscle (PM) position will vary between the 6-9 o’clock positions, while the anterolateral PM is usually seen between the 3-6 o’clock position. The RV, IVS, and LV are also visualized. (Figure 14) 

• In the critically ill patient, the mid-papillary view has the highest yield and provides the best assessment of global LV function and any wall motion abnormalities. This is the gold standard view for evaluating the shape of the interventricular septum. 

Figure 14: Parasternal Short Mid-Papillary View 

 

Apex: Finally, further tilting the ultrasound probe inferiorly until the PMs are no longer seen will generate a view of the LV apex. The RV and IVS are also visualized. (Figure 15) 

Figure 15: Parasternal Short Apex View 

Clinical Utility

The PSAX view at the mid-papillary level provides global assessment of LV function and any LV wall abnormality. The mid-papillary view also allows visualization and assessment of the interventricular septal shape when assessing the right side of the heart. 

Parasternal Long Axis View

Technique

• The ultrasound probe should be placed immediately patient left of the sternum at the level of the 3rd or 4th intercostal space 

• To obtain a longitudinal view of the heart, the probe marker points towards the right shoulder (Figure 1) 

• Depth should be adjusted to ensure the posterior pericardium and descending aorta are visible in the far field 

• Gain should be adjusted so that the myocardium appears grey and blood appears black 

• The probe should be adjusted using small movements of sliding, sweeping and rotation to optimize the view, ensuring visualization of the mitral valve, aortic outflow and the left ventricle with the septum visualized horizontally across the screen 

 

Figure 1. External landmarking for PSL image generation. 

Scanning Tips: 

• Sometimes it is necessary to slide the probe to different intercostal spaces to find the best window to view the heart, especially mechanically ventilated patients. If struggling, try each intercostal space starting from below the clavicle 

• If struggling to find a window, lying the patient in the left lateral decubitus position will aid in pulling the heart against the chest wall and the lung away from it 

• An adequate view should have the ultrasound beam directed at the mid-left ventricle to mitral valve region. Both the AV and MV should be visualized as a “double barrel” and the septum should lie as flat as possible across the screen. 

• Once a window is found, slight fanning movements should maximize the mitral valve opening and LV cavity, ideally the papillary muscles should be out of view. 

• Finally, adjust the probe through small rotational adjustments to view the ventricle in its entire length to the apex. It should appear elongated and bullet-shaped. Foreshortening the LV cavity can lead to overestimation of wall thickening and LV function. 

 

Note: Emergency vs Cardiology convention: 

The parasternal long axis view will vary in appearance on the screen whether you are using emergency or cardiology convention. With the probe marker directed to the patient’s right shoulder the images on screen will appear as mirror images of each other depending on whether your screen marker is on the left, as in emergency convention or on the right as in cardiology convention. In the emergency convention, the apex of the heart will appear screen right and in cardiology convention, it will appear screen left (Figure 2B). 

Figure 2. Parasternal Long Axis View. Cardiology convention (A) vs Emergency Medicine convention (B)

 

What Am I Looking At?

In this view a cross section of the long axis of the heart is obtained (figure 3). In the near field just below the probe a small portion of the right ventricle is visible. Below that, the interventricular septum runs across the screen. Deep to the septum lies the left ventricular cavity. In the far field the posterior wall of the ventricle is viewed along with the posterior pericardium. Finally, a cross section of the descending aorta can be appreciated at the bottom of the screen deep to the left atrium. Also visualized in this view are the left ventricular outflow tract and aortic valve just adjacent to the interventricular septum. The mitral valve and its attachments are seen deep to the aortic valve. 

Try to follow the “Rule-of thirds.” This suggests the right ventricle, aortic root, and left atrium should each generally take up 1/3 of the screen unless one is enlarged. Interpret this cautiously if slice is off-axis  

Figure 3: Parasternal long axis cross section. Retrieved from Retrieved from Wikimedia Commons: CardioNetworks ECHOpedia

Figure 4: Parasternal Long View Cardiology Convention Labeled  

Figure 5: Parasternal Long View Emergency Medicine Convention Labeled

Clinical Utility

While pathology is out of the scope of this module, the parasternal long axis view is mainly used to assess left ventricular function. It also is a good window to view pericardial effusions when the subxiphoid view is difficult to obtain. 

The Basic Cardiac Windows 

In POCUS, cardiac assessment relies on five standard views that can be used based on the clinical context: the parasternal long axis (PLAX), parasternal short axis (PSAX), apical four chamber, subxiphoid four chamber, and inferior vena cava (IVC) views.

We will review the basics of how to obtain each of the basic cardiac windows and highlight the anatomy seen in each view.

 

Emergency VS Cardiology Probe Conventions

Of note, there is often confusion regarding cardiac PoCUS in those beginning the skill as cardiologists and ICU use unique probe conventions that differ from the conventional probe and screen orientation that people are familiar with from other exam types. PoCUS practitioners view the heart in one of two ways: some choose to continue to use “emergency conventions” in which the probe marker and screen marker remain oriented to the patients right, where other PoCUS practitioners have chosen to adopt “cardiology or ICU conventions” in which the screen marker is on the right and the probe marker varies. 

While learners may choose either approach, we recommend familiarizing yourself with the cardiology convention, as it represents a higher-level standard that, while more challenging at first, offers long-term benefits in advanced imaging and interpretation. The emergency convention may be simpler and more intuitive for junior learners but is not commonly used outside of the emergency department setting. The notable exception is its standardized use for assessing pericardial effusion during the eFAST exam. 

This tutorial will cover obtaining windows in both cardiology/ICU and emergency conventions as seen in patients with a typically oriented heart. Dextrocardia and congenital heart disease will not be addressed. 

Indications 

• Undifferentiated shock (compensated vs uncompensated) or hemodynamic compromise 

• Suspicion of myocardial dysfunction 

• As part of a systematic evaluation in dyspneic patients 

 

Equipment 

• Ultrasound machine 

• Phased array ultrasound probe 

• Gel 

Introduction

Point-of-care ultrasound (POCUS) has emerged as an important tool in the assessment of shock, hemodynamics, and respiratory failure in critically ill patients. POCUS aids practitioners in coming to a diagnosis more quickly and accurately than a clinical assessment alone. This allows for more targeted and timely interventions. 

 

Why Ultrasound?

When faced with a critically ill patient with respiratory or circulatory compromise, coming to a quick and accurate diagnosis is essential. Studies from adult literature have shown PoCUS allows practitioners to come to a diagnosis more quickly and accurately than a clinical assessment alone [1, 2]. This allows for more targeted and timely interventions and in some cases has shown a mortality benefit [3, 4]. Studies have also shown that cardiac PoCUS can safely and accurately be used by practitioners at the bedside [1, 5]. This has been repeated in the pediatric literature as well [6-9]. 

Point of care echocardiography provides rapid, real-time evaluation of cardiac status in critically ill patients. It can quickly and accurately identify pericardial effusions, reduced cardiac function, right sided strain and help guide fluid resuscitation. In addition, sequential scans can monitor for effectiveness of interventions and evolution of disease. In pediatric patients, it is however important to recognize the limitations of PoCUS, particularly in the evaluation of congenital heart disease. If congenital heart disease is suspected, a comprehensive cardiology-performed echocardiogram is required, as PoCUS is not sufficient for detailed structural assessment.  

Given the benefits of PoCUS, several different protocols for evaluating critically ill patients now exist [10-15]. Further, the use of POCUS is supported by both adult and pediatric research and endorsed by professional societies [16-18].
 

This course will provide guidance on obtaining the five “standard” views of the heart utilized in point of care ultrasound: the parasternal long axis (PLAX), parasternal short axis (PSAX), apical four chamber, subxiphoid apical four chamber and IVC views. By the end of the course learners should feel comfortable in obtaining these fundamental cardiac windows and understand the anatomy they are seeing. These views provide the basic building blocks for the assessment of pathology, which is covered in other dedicated modules. 

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