Vet360, December 2016 | Page 21

Radiographic Identification of the
CARDIOLOGY

Radiographic Identification of the

Cardiac Chambers : Clockface Analogy

RA
12
A
MPA
LAu
A
LA
9
6
3
RAu
9
12
3
6
RV
LV
RV
LV
Figure 1 : DV view of the normal cardiac silhouette
Dorsoventral view 11:00 - 01:00 : aortic arch 01:00 - 02:00 : main pulmonary artery 02:30 - 03:00 : left auricle 05:00 - 09:00 : right ventricle 09:00 - 11:00 : right atrium
Figure 2 : Lateral view of the normal cardiac silhouette
Lateral view 12:00 - 02:00 : left atrium 02:00 - 05:00 : left Ventricle 05:00 - 09:00 : right ventricle 09:00 - 10:00 : main pulmonary artery & right auricle 10:00 - 11:00 : aortic arch
KEY : A = Aorta ; LA = Left atrium ; LAu = Left auricle ; LV = Left Ventricle ; MPA = Main pulmonary artery ; RA = Right atrium ; RAu = Right auricle ; RV = Right ventricle .

Calculation of 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 .
4 . Using calipers , measure the short axis at the widest part of the cardiac silhouette , perpendicular to the long axis measurement ( designated “ W ”).
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 = W + L
L4
W
W
L
Considerable breed variation exists with the VHS . The suggested mean value for dogs was 9,7 ± 0,5 v ( range 8,5 - 10,5 v ).
L
Breed specific normals have been established . Boxer - 11.6 ± 0.8 v Cavalier King Charles Spaniel - 10,6 ± 0,5 v German Shepherd Dog - 9,7 ± 0,7 v Labrador Retriever 10,8 ± 0,6 v Yorkshire Terriers - 9,7 ± 0,5 v . SOURCE : BSAVA Manual of Canine and Feline Thoracic Imaging . Eds : Toias Schwartz , Victoria Johnson , 2008
Compiled by Dr Liesel van der Merwe . Images courtesy Dr Lynelle Sweers
Issue 06 | DECEMBER 2016 | 21