radiographic examination of cardiovascular system

RADIOGRAPHIC EXAMINATION OF CARDIOVASCULA

R SYSTEMJessica C. LargadoDVM5

INTRODUCTION

Walls of the Heart Epicardium – outer serous covering Endocardium – inner endothelial lining Myocardium – consists of cardiac

muscles

INTRODUCTION

Pericadium- serous membrane- creates a closed cavity (pericardial space)- contains fluid for lubrication

INTRODUCTION

Atrium- receives the blood (veins)- thin walled chambers- with an appendage (auricle)

Ventricle- pumps blood away from the heart (artery)

Valves of the HeartAtrioventriuclar Valve – lies between the atrium and ventricle Semilunar Valve – blood flow from ventricle to artery

INTRODUCTION

INTRODUCTION

Cardiac radiography should be reserve: As a screening tool for assessing marked cardiac

abnormalities For evaluation of the pulmonary circulation To assess whether cardiac decompensation has

occurred To evaluate response to therapy

Radiographs are not very accurate for assessing either cardiovascular function or morphology

INTRODUCTION

Muscular dogs or those with a barrel-shaped thorax often have a heart that looks large

The normal heart in breeds with a laterally compressed but deep thoracic cavity, such as greyhounds and collies, can look abnormally small

INTRODUCTION

Lateral thoracic radiographs from a normal borzoi

INTRODUCTION

Normal Labrador retriever

Normal pug

VD thoracic radiographs from a normal borzoi

INTRODUCTION

Normal Labrador retriever

Normal pug

RADIOGRAPHIC POSITIONING

Ventrodorsal (VD) Dorsoventral (DV Lateral

In DV radiographs, the diaphragm is displaced cranially, which will physically push the heart cranially and into the left hemithorax.

The magnitude of this displacement is more pronounced in medium and large dogs than in cats or small dogs

RADIOGRAPHIC POSITIONING

VD (A) and DV (B)thoracic radiographs of a normal dog.

RADIOGRAPHIC POSITIONING

Alternately, VD views of the heart in large-breed dogs will have significant magnification when compared with DV views of the same heart.

It is important to realize that the cardiac silhouette is composed of tissues other than the heart.

RADIOGRAPHIC POSITIONING

The pericardium will blend with the heart, thereby contributing to the overall size and shape of the cardiac silhouette

Obese patients- fat will be visible as a region of decreased opacity immediately adjacent to the heart

RADIOGRAPHIC POSITIONING

Lateral radiograph of the thorax of a Dobrman pinscher.

RADIOGRAPHIC POSITIONING

CLOCK FACE Cardiac silhouette can be visualized in

terms of a clock face. The origin of bulges on the cardiac silhouette caused by dilation of different parts of the heart or great vessels can be predicted by using this clock analogy

CLOCK FACE

How to Calculate the Vertebral Heart Score (VHS) 1. Using a lateral thoracic radiograph, ensure

the thoracic vertebrae T4 to T12 are clearly delineated.

2. Using calipers, measure the longest axis of the cardiac silhouette from the carina of the mainstem bronchus to the apex (designated “L”).

3. Transfer this long axis measurement to the vertebrae, starting at the cranial edge of T4, and count the number of vertebrae that fall within the caliper points.

How to Calculate the Vertebral Heart Score (VHS) 4. Using calipers, measure the short axis at

the widest part of the cardiac silhouette, perpendicular to the long axis measurement (designated “S”).

5. Transfer this short axis measurement to the vertebrae, starting at the cranial edge of T4, and count the number of vertebrae that fall within the caliper points.

6. Sum the two measurements. VHS = S + L

How to Calculate the Vertebral Heart Score (VHS)

RADIOGRAPHIC SIGNSRadiographic Signs of Specific Cardiac

Chamber Enlargement

Left Atrium Left Ventricle Right Atrium Right Ventricle Generalized Cardiomegaly

LEFT ATRIUM Most frequently encountered cardiac

enlargement

Almost always caused by dilation

Left atrial dilation is usually a result of mitral valve disease but can occur with left-to-right pulmonary overcirculation causing volume overload of the left atrium

LEFT ATRIUM In the lateral view, dilation of the left

atrium causes a change in shape of the dorsocaudal aspect of the cardiac silhouette.

Formation of a slight concavity on the caudal margin of the heart

Lateral radiograph of a dog with a dilated left atrium. The enlarged atrium has created a concave shape change on the caudal margin of the heart (white arrow). This is a very common sign of left atrial dilation.

LEFT ATRIUM

Left atrial dilation also causes an increase in height of the caudodorsal heart border and elevation of the tracheal bifurcation.

If left atrial dilation is severe, the left principal bronchus may become selectively elevated or even compressed between the left atrium and adjacent tissues dorsally

LEFT ATRIUM

Lateral (A),DV (B),radiographs in a dog with marked left atrial dilation. In A,there is elevation of the trachea and compression of the left principal bronchus as it is trapped between the left atrium and tissues dorsal to the heart (black arrow).The left cranial lobe pulmonary vein is also distended (white arrow), consistent with pulmonary venous hypertension. In B, the dilated left atrium appears as a region of increased opacity caudal to the tracheal bifurcation (black arrows)

LEFT ATRIUM

Dogs with bronchial compression secondary to left atrial dilation may exhibit a cough

A massively dilated left atrium may also lead to a region of increased opacity superimposed over the cardiac silhouette in the VD or DV view that creates the appearance of a double wall

LEFT ATRIUM

Lateral (A)and DV (B)radiographs of a dog with extreme dilation of the left atrium.

LEFT ATRIUM

Dilation of the left atrial appendage (auricle) occurs less frequently than dilation of the left atrium 2 to 3 o’clock position

An extremely enlarged left atrium can also result in lateral displacement of the left auricle, resulting in its visualization without the auricle actually being dilated

LEFT ATRIUM

DV radiograph of a dog with pronounced left atrial dilation. The enlarged atrium has caused abaxial displacement of the principal bronchi (black arrows).There is also a bulge on the left aspect of the cardiac silhouette that is consistent with left auricular dilation or lateral displacement of the left auricle by the dilated left atrium (white arrows).

LEFT ATRIUM

May enlarge as a result of hypertrophy or dilation

Concentric hypertrophy

Eccentric hypertrophy

LEFT VENTRICLE

Lateral view Straightening of the caudal cardiac silhouette Elevation of the trachea and carina

DV View Enlarged left ventricle may elongate the

cardiac silhouette Cardiac apex may appear rounder and be

displaced to the left

LEFT VENTRICLE

response to chronically increased preload and is often associated with cardiac failure

Dilation of the left ventricle may either contribute to an overall appearance of generalized cardiomegaly or result in the elongation of the left ventricle, causing the tracheal elevation

LEFT VENTRICLE

Radiographic detection of an enlarged right atrium is uncommon.

Visualization of isolated right atrial enlargement can be found in dogs with tricuspid dysplasia

RIGHT ATRIUM

When visible in the lateral view, right atrial enlargement causes a bulge or mass effect in the craniodorsal aspect of the cardiac silhouette.

In the VD or DV projection, an increased bulge in the right heart border from the 9 o’clock to 11 o’clock position may be present.

RIGHT ATRIUM

Left lateral (A)and DV (B)radiographs of a Labrador retriever with tricuspid dysplasia.

RIGHT ATRIUM

May enlarge as a result of hypertrophy or dilation

Common causes of hypertrophy are heartworm infection and pulmonic stenosis

RIGHT VENTRICLE

In VD or DV views, a hypertrophic right ventricle appears more rounded and protrudes farther into the right hemithorax than normal, giving the cardiac silhouette a reversed letter D shape

RIGHT VENTRICLE

RIGHT VENTRICLE

Results from combinations of chamber enlargement, or all four chambers

Myocardial dysfunction

GENERALIZED CARDIOMEGALY

GENERALIZED CARDIOMEGALY