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and longitudinal changes of the left ventricle during the cardiac cycle; however, the
same cannot be said for the study of the circumferential cardiac movement of
torsion. In recent years, mainly in human medicine (Thomas and Popovic
2006
)
but also in veterinary medicine (Estrada and Chetboul
2006
; Schwarzwald et al.
2009
), two new parameters, strain and strain rate, which are able to quantify a
percentage of myocardial displacement, have been taken into consideration. Such
indices are obtained through tissue Doppler imaging (TDI) or 2D speckle tracking
(2DST). In comparison with TDI, 2DST is independent from the Doppler angle of
incidence and appears to be more promising for the evaluation of both regional and
global cardiac motion, not only radial and longitudinal but also circumferential
(Schwarzwald et al.
2009
; D'Andrea et al.
2009
). Therefore, the aim of the present
study was to verify whether the application of 2DST, through the software
X-Strain
®
of Esaote, allows the making of some considerations inherent to
variations of strain and strain rate in dogs affected by left ventricle reduced
contractility, prior to and after the beginning of treatment. Furthermore, eventual
variations of both m-mode and b-mode parameters will be considered. The eventual
positive result of this variation could justify the necessity to comprehend the
application of X-Strain
®
in veterinary medicine during echocardiographic exami-
nation. In fact, it could be useful not only to study in more detail the pathogenesis
and evolution of diseases characterized by alterations of myocardial contractility
but also to optimize therapeutic protocol during patient follow-up and to individu-
alize some normal values of the X-Strain
®
indices that are currently unavailable for
dogs.
16.2 Materials and Methods
A crossbred male dog, 45 kg, 9 years old (case 1), and a Harlequin male Great Dane,
68 kg, 5 years old (case 2), both with an anamnesis of cough and exercise intoler-
ance, underwent physical and echocardiographic examination before (
T
0
) and
16 weeks and 15 days (respectively) after (
T
1
) the diagnosis of dilated cardiomy-
opathy and the consequent beginning of therapy with inotropic drugs (i.e.,
Pimobendan 0.25 mg/kg per os every 12 h and Digoxin 0.005 mg/kg per os every
12 h, respectively), Furosemide (2 mg/kg per os every 12 h), and Benazepril
(0.25 mg/kg per os every 24 h). m-Mode, b-mode, and 2DST evaluations were
performed after trichotomy, degreasing, and ultrasound gel application on the right
and left parasternal views, with the patient initially in the right and then in the left
recumbency. The ultrasound examinations were performed with the echograph
Esaote “MyLab30-Vet,” with the software X-Strain
®
and a multifrequency-phased
array probe (1-4 MHz). Therefore, for each patient at
T
0
and
T
1
, the following
m-mode and b-mode parameters were estimated: interventricular septum at end-
diastole (IVSED) and at end-systole (IVSES), end-diastolic (LVEDD) and
end-systolic (LVESD) left ventricle diameter, left ventricle posterior wall at end-
diastole (LVWED) and at end-systole (LVWES), interventricular septal thickening
