Cardiac Ultrasound

Learning objectives:

Key points:

A phased array probe is used and settings should be changed to "cardiac". This means the probe marker on the screen will be on the right side of the screen
Cardiac structures (and almost any other structure in medical imaging) should be visualized in at least 2 imaging planes
The text in this module will focus on image acquisition, the following module will focus on basic interpretation and pathology
4 Basic questions are answered with cardiac POCUS:
- (1) How is the left ventricle (LV) functioning?
- (2) How is the right ventricle (RV) functioning?
- (3) Is there a pericardial effusion?
- (4) What is the fluid status?
- In order to be able to answer these questions one should be able to obtain and recognize all of the anatomic structures in all of the basic views first

Parasternal long-axis view (PLAX)

How to obtain this view:

The transducer is placed to the left of the sternum anywhere between the 2nd and 5th intercostal space
The parasternal window is able to be acquired in most patients regardless of position
The transducer marker should be placed toward the patient's right shoulder
The heart is "cut" by the ultrasound beam at its long axis (from base to apex)

Key structures that must be recognized in this view are:

- Aortic valve (AV), mitral valve (MV), left ventricle (LV), pericardium (anterior and posterior), right ventricle (RV), right ventricular outflow tract (RVOT), and portions of the ascending and descending thoracic aorta may also be seen

PLAX is used to mainly assess LV size and function, aortic and mitral valves, and left atrial size
Also helps distinguish a pleural effusion, behind the thoracic descending aorta, from a pericardial effusion, in front of thoracic descending aorta

parasternal long axis 2d video.mp4

(you can right click on the videos and loop them)

How to obtain this view:

- Start with the PLAX view
- Center transducer over the MV and and rotate 90 degrees clockwise (can use both hands to ensure probe stays in position)
- Marker should now be pointing to the patient's left shoulder

Both anterior and posterior valves of the MV should be visualized (the "fish mouth")

"The fish mouth"

A fish with its mouth open

PSAX: Mitral valve level (papillary muscles can be seen briefly at the end of the clip as the operator fans down)

Five different imaging planes can be obtained from this view. For our purposes we will only focus on reliably obtaining the mitral valve level and mid-ventricular level.
Fanning up and down allows us to obtain the other planes which are from the base to the cardiac apex
- Cardiac base: Pulmonary artery level and aortic valve level
- Mitral valve level: "The fish mouth" obtained when rotating from the PLAX view
- Mid-ventricular (papillary muscle level): the most useful when performing POCUS
  - Both papillary muscles should be seen and appear symmetrical
  - Image should be as circular as possible (an oval shaped image indicates probe is off-axis)
  - This view allow for global assessment of LV function and segmental wall motion
  - Helps assess the shape of interventricular septum, especially when RV is dilated
  - Pericardial effusions are also seen (moderate to large)
- Apical level: Does not provide significant amount of additional information (except when a thrombus is seen)

Normal PSAX view: papillary muscle level

Mid ventricular view (both papillary muscles are seen)

How to obtain this view:

It can be one of the more challenging views to obtain especially in obese or mechanically ventilated patients
Patient should be placed in a left lateral decubitus position if possible, images can be obtained with the patient supine but it may be more difficult to obtain them
From the PLAX view slide the probe inferolaterally towards the apex (6th intercostal space at the mid-clavicular line or below the left nipple)
The orientation marker should end up pointing towards the patient's left side

This view allows assessment of RV systolic function along with evaluation of the MV and TV
Pericardial fluid can also be detected
Additional apical views can be obtained (eg. apical 5 chamber) but they are not part of a standard POCUS exam

How to obtain this view:

- Place the transducer immediately below the xiphoid process (also called subxiphoid view)
- Orient probe marker to patient's left side
- Press down firmly, probe should almost be flat against the patient under the xiphoid process, patient may experience some discomfort with this maneuver
- Ask the patient to bend the knees if having difficulty
- Pro tip: use the liver as an acoustic window (slide probe to the right of the patient and point it towards the heart)

The RV, LV, RA, LA and pericardium should be seen
Can assess RV systolic function with this view, also RV free wall can be seen
High sensitivity to assess pericardial effusion, ideal to assess diastolic collapse of right-sided chambers in tamponade
The LV can also be seen and a rapid assessment of global LV systolic function can be done

How to obtain this view:

- From the subcostal view rotate the probe counterclockwise 90 degrees
- The marker should now be pointing towards the head of the patient
- Tilt the transducer to aim posteriorly, may need slight adjustment by fanning and rocking to center the RA-IVC junction on the screen
- On the screen you should be able to see the hepatic vein draining into the IVC right before the RA

IVC 2d video.mp4