Cardiac
Cardiac POCUS is one of the most useful and important skills you can have when evaluating a patient at the bedside. Ejection fraction, pericardial effusions, valvular disease, large vegetations, wall motion and more can all be visualized and give you the diagnosis in seconds. We will go through the steps of a bedside exam. To become proficient in cardiac POCUS, you need to master 4 views: parasternal long, parasternal short, apical 4 chamber, and subcostal.
Parasternal Long
This view is the starting point for the cardiac evaluation. It is great for locating the heart, getting a first estimate of the Ejection fraction (EF), assessing left ventricular size, quickly evaluating for a pericardial effusion and getting a first look at the mitral and aortic valves.
Patient & probe positioning
Place patient in supine or left lateral decubitus position if possible. Start to the left of the sternum and slide the probe down the chest until you reach the 2nd - 4th intercostal space with marker pointing toward patient's right shoulder
Interpreting the image
If you take a longitudinal slice down the center of the heart and look into the heart from the patient's left side, you will get the parasternal long view.
From the top of the image, you can see the subcutaneous tissue/ribs/intercostal muscles just below the probe, and the first structure you will see in the RV outflow tract. Posterior to that is the left ventricle.
Parasternal Short
Parasternal short (PSS) is a great view to complement what you saw on the PSL. PSS is a cross sectional view into the heart where you can more easily compare the diameters of the LV and RV side by side, and visualize the LV contraction in the transverse plane.
Patient & probe positioning
Patient remains in same position as parasternal long. Once you found the parasternal long view, slowly rotate the probe 90 degrees so the marker is now pointing to the patient's left shoulder. You must hold the probe very steady when doing this.
Interpreting the image
In Parasternal short view, you can see a transverse section of the left & right ventricle. If you fan up towards the left shoulder or down toward the apex, you can inspect the different regions of the LV.
In the center of the LV (pictured below), you can visualize the posteromedial papillary muscles and the Anterolateral papillary muscles, as well as look with the RV and LV function. This is an excellent level to evaluate for global LV systolic function & regional wall motion abnormalities.
It is also a great view to assess relative size of RV and LV. Usually the RV should be smaller or equal to LV. As the RV dilates, it will become rounder, and eventually larger than the LV. Once the RV:LV ratio is > 1, this is abnormal. As the pressure in RV increase (severe volume overload, PE, Pulmonary hypertension), The RV will compress the LV and flatten the left ventricle.
Apical 4-chamber view
The third view to master is the apical 4-chamber. This gives you an excellent view of the left and right side of the heart, side by side. It is useful for evaluating LV and RV systolic function, tricuspid or mitral regurgitation, and apical and posterior pericardial effusions. It is also one of the most difficult to find. In female patients, it can be more difficult as you need to maneuver around the breast tissue.
Patient & probe positioning
You are trying to place the probe directly on the apex, or PMI. Patient should be in left lateral decubitus. If you can palpate the PMI, you can start by placing the probe there.
Otherwise, start with the PSS view and slide down the chest infero-laterally about 1 inch inferolateral to the left nipple in men and just underneath the inferolateral quadrant of the breast in a female. These positions are rough estimates, and are dramatically different depending on what cardiopulmonary pathology the patient may have.
With the marker facing the patient's left side, fan the probe up so the beams are directed toward the right shoulder.
Interpreting the image
The septum should be centered and as close to vertical as possible. This is an excellent view to evaluate the RV and LV function side by side. This is also the best view to evaluate for tricuspid and mitral regurgitation.
To differentiate the left and right side, the RV is generally more triangular and the tricuspid valve is more proximal to the apex than the mitral valve. There is also a moderator band in the Right ventricle that can be visualized sometimes.
If the RV is the same size as the LV, there is moderate RV enlargement. If the RV > LV, you have severe RV enlargement.
Subcostal view
The last view is the subcostal view, which can be an excellent tool to compare the relative size of the RV and LV, get a closer look at the mitral and tricuspid valves, and evaluate for pericardial effusions.
Patient & probe positioning
With patient supine, place probe just under their xiphoid process with the probe marker to the patient's left side. Have them bend their knees to relax their abdominal muscles.
To get a good image, you also will have to ask the patient to take a deep breath in and hold (this pushes the diaphragm down, revealing the heart).
Interpreting the image
At the top of the image will be a small portion of the liver. Just distal to that is the pericardium then the RV. The Subcostal view is great for looking for pericardial effusions and re-examining the mitral and tricuspid valves.
In many patients, they will have poor windows with their apical 4-chamber views, and subcostal view may be a viable alternative.