Focused Cardiac Ultrasound - SD

Introduction to Focused Cardiac Ultrasound

I am Von K.

I'm a assistant professor
of emergency medicine at Thomas Jefferson University in
Philadelphia, and I'll be speaking about how
to do a focused cardiac ultrasound examination.

This lecture will provide an overview on how
to perform a focus cardiac ultrasound.

I will not be describing how to do a complete echocardiogram
as performed by cardiologists,
and I want to stress
that a focused cardiac exam should not be a
substitute for a complete one.

The focused cardiac ultrasound is a two dimensional,
transthoracic examination
that involves imaging the heart in the four
views represented here.

At the end of this lecture, you'll be able
to identify these views
and be able to learn the technique in order to perform them.

Purpose of Focused Cardiac Ultrasound

The purpose of the focus cardiac ultrasound examination is
to help the clinician evaluate a patient presenting
with cardiac trauma, hypotension, chest pain, dyspnea,
and pulses electrical activity in the emergent setting.

Those of us who evaluate
and treat patients in the emergent setting
know it can be difficult
to obtain a complete cardiac ultrasound performed
by an echo cardiologist in a timely manner.

The American Society of Echocardiography recognized the need
for a focused cardiac examination.

In 2010, the Society
and American College of Emergency Physicians published a
consensus statement describing the use of a focused exam.

Primary Goals of Focused Cardiac Ultrasound

The primary goals of a focused cardiac exam are
to determine whether or not there is a pericardial effusion and to assess global systolic function.

I will be focusing on these two for this lecture.

The other goals are to assess for intravascular volume
and to help with procedures that include pericardiocentesis
and transvenous pacing.

Limitations of Focused Cardiac Ultrasound

It's important to recognize the limitations
of a focused cardiac ultrasound.

It will not assess for valvular pathologies,
masses thrombus, while motion abnormalities
and is unable to reliably rule out aortic dissection
or endocarditis.

But with experience, you might be able to make some
of these diagnoses as well.

Imaging the Heart: Transducer Planes and Positioning

So in order to image the heart in three orthogonal views,
four basic transducer planes will be obtained.

A four chamber, subcostal or subxiphoid view the peral long
and short axis and the APCO four chamber view.

Because the heart is surrounded by air fill lungs,
air interferes with the transmission of ultrasound waves.

There are only a few windows that allow us
to peek into the heart with the exception
of the subcostal view.

The ideal patient positioning is in a left lateral decubitus
position with the head of the bend elevated to about 20 to 30 degrees.

You want to use the phased array probe.

It has frequencies ranging from two to five megahertz.

Its compact shape enables it
to easily fit into the intercostal spaces.

It would be very difficult
to perform a cardiac ultrasound with the curva linear probe because it doesn't allow you
to get in between the rib spaces.

Most ultrasound machines have cardiac presets
that optimize frequencies
and tissue harmonics for imaging the heart.

Screen Orientation

So a lot of people get confused by
where the screen marker should be located.

For abdominal and pelvic exams,
the indicator is usually on the left hand side
of the screen, but for echocardiographers, the standard is
to have the indicator on the right side of the screen.

It's important to recognize this
because flipping the screen indicator will
flip your cardiac image.

Subcostal View

Let's start off with the sub cost of view.

This is the view normally used as part of the,
fast exam.

In the assessment of trauma patients,
the sub cost of view allows for vis visualization
of all four chambers.

Here's the liver, the left ventricle, right ventricle,
left atrium, and the right atrium.

The ultrasound beam will be perpendicular
to the interventricular and inter atrial septa.

This view is especially helpful in looking at the heart in a
barrel chested patients
because the other views may be difficult to obtain.

Again, here's the liver, the left ventricle,
right ventricle, left atrium, and right atrium.

The ideal patient positioning is in the supine position.

And in order to obtain the subcostal view,
you'll use the liver as an acoustic window.

It's important to remember to keep the probe bengal shallow to the body.

A common problem with novices is to hold a probe
to perpendicular, keep the probe marker
pointed to the patient's left.

Parasternal Long Axis View

Now let's discuss the peroneal lung axis.

Personally, I think this is the easiest view to obtain.

You want to place the probe perpendicular
to the chest wall in either the third
or fourth intercostal space left of the sternum.

For this view, you wanna keep the probe perpendicular
as opposed to a subcostal view where
we kept the angle low to the chest
and point the probe marker to the patient's right shoulder.

Better views can be obtained if you keep the patient towards his or her left side.

You want to rotate the probe so that the aortic
and mitral valves are in the same plane.

And for this view, you'll be able
to visualize the left ventricle, the right ventricle,
intraventricular septum, mitral valve,
and aortic outflow track.

Parasternal Short Axis View

Next view would be the paranal short axis.

So once you have the probe
and the paranal long axis,
the short axis is literally just a twist away.

The paranal short axis allows you to look at the heart
and cross sections.

This will result in three distinct para sternal views
going from the base to the apex of the heart.

You'll come to the levels of the aortic valve,
the mitral valve, and the papillary muscles.

In order to obtain the paranal short view,
simply rotate the probe about 90 degrees counterclockwise
from where you had it in the peral long position.

The pro marker will now point
to the left shoulder instead of the right.

Then you can sweep across the heart from the base
of the apex in order to obtain cross-sectional views
of the heart at the levels of the aortic valve,
miral valve, and papillary muscles.

This clip shows the paranal short axis at the level
of the papillary muscles here
and going to the mitral vol mitral valve.

And you could see here the paranal short axis at the level
of the AIC valve.

And this is also known as the Mercedes-Benz sign.

Apical Four Chamber View

Now we'll get to the APCO four chamber,
which will be our last cardiac view.

And the APCO four chamber will allow you
to visualize both ventricles, the atria
and the a atrial ventricular valves.

The apical four chamber view provides a chal view
of the heart, and you'll be able
to visual visualize a septal, apical
and lateral walls of the left ventricle.

There's a right ventricle, the left atrium
and the right atrium.

I find the four chamber view is actually the most difficult to obtain,
but with a little bit of practice, you'd be able to perform it with ease.

You want to place the probe in the fifth intercostal space.

Usually you need a point of maximal impulse aim.

The probe towards the right shoulder
with the probe marker to the left.

And patient positioning really helps in this view.

You want to try to put the patient towards his
or her left side.

And here's a clip of the four chamber view
with the left ventricle, right ventricle, left atrium,
and right atrium being demonstrated with experience.

Assessing Left Ventricular Function

It's possible to determine gross left ventricular function
just by visual estimation.

Calculating an injection fraction in a full cardiac
ultrasound, it's complicated.

It involves measurements
of the left ventricular cavity
dimension, and wall thickness.

It's really beyond the scope of a focus cardiac exam.

But it has been shown that in the literature that a gross ejection fraction estimation
can be accurately obtained.

Here are two clips. One is demonstrating a normal injection
fraction, and this is these are both in a peroneal short axis,
and this clip demonstrates a heart
with an injection fraction less than 10%.

Review of Cardiac Views

So for a review, here's a liver,
the left ventricle, right ventricle, left atrium,
right atrium, and this is the subcostal
or the subxiphoid view.

Here's the left ventricle and the right ventricle,
and this is the peral short axis.

We have the left ventricle here, the right ventricle,
left atrium, and right atrium.

And this is the apical four chamber view.

Again, here's the left ventricle, right ventricle,
left atrium, and the aortic outflow tract.

And this is the peral lung axis.

Troubleshooting Cardiac Ultrasound Images

So when performing cardiac exam,
if you're having trouble obtaining correct images,
keep these questions in mind as a patient in the correct position.

Oftentimes,
you will obtain a better image if you placed a patient in
his or her left side,
and with a head of the bed elevated to about 20
to 30 degrees.

Ask yourself as a transducer in the correct position,
try sliding the transducer under
and over the ribs in order
to obtain a better acoustic window.

Are my images rotated?

Your transducer may be in the correct place,
but the pro marker is not.

And if your images don't appear crisp,
make sure you are on the cardiac presets on your ultrasound
machine and not in the abdominal presets.