Page 167 - Feline diagnostic imaging

168 10 Normal Cardiovascular Imaging

Figure 10.19 Image in the near field is the 2D image of the right and left ventricle at the level of the papillary muscles. The image
in the far field represents the M-mode tracing of the right and left ventricle in real time. The cursor is placed within the 2D image
with the M-mode image depicting the normal interventricular septum (IVS), left ventricular internal diameter (LVID), and left
ventricular free wall (LVFW) in systole and diastole.

Figure 10.20 Image in the near field is the 2D image of the aorta and left atrium. In the far field is the M-mode tracing of the aorta
(Ao) and left atrium (LA).

measurements of the LA are not interchangeable even evaluating left atrial size in 30 healthy cats measured using
when indexed to the aortic size. In 17 healthy normal feline M‐mode or 2D images at the heart base, the maximum
patients, the size of the LA on M‐mode and 2D images was diameter was less than 1.01 cm [6]. As a rule of thumb, the
no larger than 1.33 cm and 1.2 cm respectively. The mean LA at the heart base measured from the 2D image should
ratio of the LA to aorta measured by M‐mode or from the not be larger than 1.5 cm [7].
2D image in the normal cats was 1.29 and 1.1 respectively. In addition, the size of the LA should be measured from
In the same study, the LA in 20 cats with hypertrophic a right parasternal long axis view. To obtain this image,
cardiomyopathy measured no larger than 1.96 cm on M‐ the probe should be rotated 90° and positioned perpendic-
mode and 1.73 cm on the 2D image [5]. In another study ular to the thoracic wall without tipping the probe.