Introduction to Bedside Cardiac Ultrasound

CHAPTER 1

Bedside cardiac ultrasound is a key component in the treatment and care of critically ill patients. The goal of this video is to introduce you to the basics of bedside point of care cardiac ultrasound. After watching this video, you should be able to identify the four views that make up the point of care cardiac ultrasound, their uses, how to obtain these views as well as their function in patient care. Although we are covering the basics of point of care cardiac ultrasound, we will not review knobology or physics in this video. Knowledge of these topics is a prerequisite of the material covered today. The images that we are showing you today can sometimes be difficult to obtain due to body habitus, patient positioning, or user experience. Indications for limited bedside cardiac ultrasound include: cardiac arrest, unexplained hypotension, syncope, shortness of breath, chest pain, and altered mental status. There are no absolute contraindications for limited bedside cardiac ultrasound. During this video, we are going to discuss the four cardiac views that comprise the bedside cardiac ultrasound. These views include the parasternal long, the parasternal short, the apical four chamber, as well as the subxiphoid view. The probe used to obtain the images in the bedside cardiac ultrasound is the phased array probe, which you see here. It's important to note that limited bedside cardiac ultrasound can be assessed using two different screen orientations. One is the more conventional abdominal imaging, where the indicator is on the right side of the screen. The other is in line with the formal echocardiography, which has the indicator on the left side of the screen. The latter orientation we will be reviewing in this video today.

CHAPTER 2

The first view of the bedside cardiac ultrasound is the parasternal long. For this view, you are going to use the phased array probe. It's important for the patient to be supine and flat for this view. It is important that the probe is perpendicular to the chest wall. Starting just lateral to the sternum at the second intercostal space with the indicator pointed to the patient's right shoulder, you are going to look for the cardiac window. Here, you are going to slide just downward one interspace at a time until the cardiac window comes into view. In this view, you will be able to identify the right ventricle, the left ventricle, the left atrium, the mitral valve, the aortic valve, the aortic outflow tract, as well as the descending aorta.

Parasternal long pearls. Patient positioning. Make sure the patient is supine. It can be helpful to put a towel roll underneath the patient's right shoulder. Doing so brings the heart more anterior to the chest wall and also drops the patient's left lung out of view via gravity. Probe positioning. Make sure to anchor your hand on the patient's chest wall. Doing so allows you to optimize your view by being anchored and stable in fanning and rotating the probe. Parasternal long pitfalls. It's important not to be too medial over the sternum as well as too lateral over the lungs because both of these positions will obstruct your view. Depth. Make sure that you set your depth deep enough so you're able to visualize the descending aorta. This is imperative because it allows you to identify a pericardial or pleural effusion, which we will talk about in pathology.

Pathology. In this view, you are able to quickly identify and assess a pericardial effusion, as well as left ventricle function. A pericardial effusion appears as an anechoic space between the epicardium and the pericardium. It's important to differentiate between pericardial effusions, which run anteriorly and medially to the descending aorta, versus pleural effusions, which run posteriorly and laterally to the descending aorta. Pericardial effusions can cause pericardial tamponade physiology, particularly when development of the effusion is acute. Tamponade is most readily detected on bedside ultrasound by assessing for right ventricle collapse during diastole. While qualitative assessment of ejection fraction is beyond the scope of a bedside assessment, point of care cardiac ultrasound is useful in a qualitative assessment of global left ventricle function. Systolic function is evaluated based on a gross assessment of left ventricle volume changes, as well as anterior mitral valve leaflet excursion.

CHAPTER 3

The second view of the bedside cardiac ultrasound is the parasternal short. For this exam, you will again use the phased array probe. Starting from the positioning of the parasternal long view, you are going to anchor your hand and rotate the probe 90 degrees with the indicator pointed to the patient's left shoulder. This view allows for evaluation of the left ventricle function, symmetry of squeeze, and septal bowing. In this view, you're able to identify the left ventricle, which appears as a circle, and the right ventricle, which appears as crescent-shaped.

Pearls and pitfalls. As with our prior imaging in the parasternal long, it's important to have the patient positioned correctly, as well as have the probe placed correctly against the chest wall. The probe is mobile. Again, remember you can rotate and fan the probe to optimize your view. There is one pitfall that is particular to the parasternal short view. Aiming the probe too apically instead of at the level of the papillary muscles will give you an incorrect assessment of left ventricle function.

Pathology. As with the prior view, we can assess for global systolic function and pericardial effusion in the parasternal short. This view is particularly useful for identifying increased right ventricle pressures, which manifest as septal flattening and septal bowing.

CHAPTER 4

Apical four chamber view. For this exam, you again will use the phased array probe. For this view, you're going to place the indicator to the patient's left side, and you are going to put the probe at the point of maximal impulse. Here, we're going to angle the probe cephalad towards the base of the heart. In addition to some of the pathologies discussed in prior views, the apical four chamber view allows for comparison of right and left ventricle sizes. A normal right ventricle to left ventricle ratio is 0.6 to 1.0. This view allows for visualization of the left atrium, the mitral valve, the left ventricle, the right atrium, the tricuspid valve, and the right ventricle.

Pearls. Patient positioning. The left lateral decubitus is the best position to optimize your view. Probe positioning. Unlike in prior views, when you want the probe perpendicular to the chest wall, here, in the apical four chamber view, you want to make sure that you are angling your probe up towards the base of the heart. Pitfalls. This is the most challenging view, and patient positioning is critical. You will likely need to use a towel roll as discussed in prior views.

Pathology. This view is particularly useful for assessing right ventricle hypertrophy, increased right ventricle pressures, and McConnell's sign.

CHAPTER 5

The final view of the bedside cardiac ultrasound is the subxiphoid or subcostal view. For this view, we are going to use the phased array probe. Alternatively, you can use the curvilinear probe. For the subxiphoid view, with your indicator to the patient's left side, you're going to find the xiphoid process. Here, just going inferior into the right of the patient's xiphoid, you are going to apply downward pressure while angling cephalad and into the left chest. Here, you use the left liver lobe as an acoustic window to enhance your image. For this view, you can see the liver lobe is at the top of your screen, and going downward, you can see the right ventricle and the left ventricle. Depending on the angle, you can see the right atrium and left atrium in this view as well.

Pearls. Patient positioning. Make sure the patient is supine and flat. Probe positioning. It's important here that you angle the probe cephalad while applying downward pressure into the abdomen. Additionally, you can ask your patient to take a deep breath and hold it. Doing so inflates the lungs and brings the heart closer to your probe. Pitfalls. Getting the subxiphoid view can be difficult for numerous reasons. One can be body habitus of your patient. Two can be increased gas in the bowel. Three can be if there's any trauma over the abdomen, or if the patient is unable to tolerate the pressure you're using to get this view.

Pathology. This is the best view to evaluate for the presence or absence of a pericardial effusion. If present, you will see a pericardial effusion in between the liver lobe and the right ventricle at the top of your screen.

CHAPTER 6

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