Case 5: Get Along Little Buddy

True = common leads to left atrial enlargement

In our canine patients, mitral valve disease is the most common acquired heart disease.

TRUE OR FALSE

False

The only pathologic process that causes the trachea to be elevated from its normal position (diverging from the spine) is cardiomegaly.

TRUE OR FALSE

True

Patient positioning is critical when evaluating the cardiac silhouette.

TRUE OR FALSE

Size and shape

What two Roentgen signs are important when evaluating the abnormal image?

A. Right atrium

B. Left atrium

C. Right ventricles

D. Left ventricles

Identify the labeled structures

Canine Left lateral and VD thoracic projections are available for review.

Describe the study (views and anatomy)

Patient positioning is adequate for interpretation.

Study technique is adequate for interpretation.

note: there is good superimposition of the rib heads

Describe patient positioning and technique

The cardiac silhouette is enlarged, being both too tall and too wide. There is marked left atrial enlargement which is causing left mainstem bronchus compression. The trachea is elevated. The pulmonary vessels are not enlarged and the pulmonary parenchyma is unremarkable. The pleural space is unremarkable. No abnormalities are identified within the extra-thoracic structures.

Describe your findings using roentgen signs

Left atrial enlargement and left mainstem bronchus compression with no radiographic evidence of pulmonary venous congestion or pulmonary edema. These findings are most consistent with mitral valve disease.

Describe your conclusion: Give your radiographic diagnosis and list possible differential diagnoses for all your findings

Echocardiography could be considered to further evaluate cardiac structure and function.

Describe Next Steps: Are there any additional imaging suggestions that would help clarify your findings? Are there critical next steps to take from a stabilization/management/treatment plan standpoint?

Middle

What part of the mediastinum is the cardiac silhouette located in?

Trachea is elevated dorsally

This is a left lateral of a dog. Heart is too tall and too wide which you can tell WHY? Because of deviation of what other structure?

Soft tissue muscle of the heart and the fluid within the heart are the same opacity = cannot delineate margins

Why is it hard to interpret the cardiac silhouette of an animal on radiographs?

Left atrium = can tell from "cowboy sign" which is when the trachea comes down and the primary/principal bronchus curves out

What structure sits here in the VD view? How can you tell it is enlarged?

Number, size, opacity, margin, shape, position

List the roentgen signs

The one WITH the arrow - NORMAL

note: the one without the arrow is a patient with congestive heart failure

Which of these images is normal, the one with the arrow pointing to it OR the one without the arrow?

Caudal margin of the cardiac silhouette is not visible because of increased opacity in the caudodorsal lung fields, which is pulmonary edema

How can you tell the image on the right has congestive heart failure?

note: the left image is normal

It is not likely = no pulmonary edema

Does this dog have congestive heart failure? How can you tell?

Systolic murmur

What kind of murmur will you hear with mitral valve disease at the 5th IC space?

Between the left atrium and left ventricle

Where is the mitral valve located?

Between the left ventricle and out to the circulatory system (aka body)

Where is the aortic valve located?

True

Left atrial enlargement often results in the "bow-legged cowboy" sign.

TRUE OR FALSE

xx

for reference on cowboy sign

b. Right Ventricle

What is structure A?

a. Main Pulmonary Artery

b. Right Ventricle

c. Caudal Lobar Arteries

1. A) Left Atrium B) Left Ventricle

Identify the structures labeled A and B:

1. A) Left Atrium B) Left Ventricle

2. A) Left Ventricle B) Left Atrium

3. A) Ascending Aorta B) Left Ventricle

LINE: aorta

CIRCLE: left atrium

What are the DOTTED LINE and DOTTED CIRCLE representing, respectively?

Aortic arch

What structure would be located at 12 o'clock?

Main pulmonary artery

What structure would be located at 1-2 o'clock?

Left auricle

What structure would be located at 3 o'clock?

Left ventricle

What structure would be located at 3-6 o'clock?

Right ventricle

What structure would be located at 6-9 o'clock?

Right atrium

What structure would be located at 9-11 o'clock?

True

note: This is because the mitral valve becomes "leaky" and allows some blood to move in the wrong direction, back into the left atrium. The left atrium responds to this increase in volume by dilating

The main reason the left atrium gets big with mitral valve disease is because of left atrial volume overload.

TRUE OR FALSE

A. Cranial Lobar Artery

B. Cranial Lobar Vein

C. Enlarged Left Atrium

D. Caudal Vena Cava

What are the structures located at A, B, C, and D respectively?