Pulsed Tissue Doppler Imaging in Normal Cats and Cats with Hypertrophic Cardiomyopathy

Abstract

Myocardial motion was quantified in normal cats (n = 25) and cats with hypertrophic cardiomyopathy (HCM) (n = 23) using the pulsed tissue Doppler imaging (TDI) technique. A physiologic nonuniformity was documented in the myocardial motion of normal cats, which was detected as higher early diastolic velocities, acceleration, and deceleration in the interventricular septum compared with the left ventricular free wall (LVFW). HCM cats exhibited lower early diastolic velocities, acceleration, and deceleration and also prolonged isovolumic relaxation time compared with normal cats. These differences were detected mainly along the longitudinal axis of the heart. A cutoff value of E' in the LVFW along the longitudinal axis >7.2 cm/s discriminated normal from HCM cats with a sensitivity of 92% and a specificity of 87%. The physiologic nonuniformity of myocardial motion during diastole was lost in affected cats. Systolic impairment (decreased late-systolic velocities in most segments along the longitudinal axis and decreased early systolic acceleration in both mitral annular sites) was evident in HCM cats irrespective of the presence of left ventricular outflow tract obstruction and congestive heart failure. Postsystolic thickening was recorded in the LVFW along the longitudinal axis only in affected cats (n = 6) and was another finding indicative of systolic impairment in the HCM of this species. This study identified both diastolic and systolic impairment in cats with HCM compared with normal cats. The study also documents the normal physiologic nonhomogeneity in myocardial motion in cats and the subsequent loss of this feature in the HCM diseased state.

Evaluation of Feline Cardiomyopathies

“…The maximum velocity of the mitral annulus S′ wave is also reduced in HCM, illustrating a systolic dysfunction not detectable by TM mode [29].…”

“…They include [29][30][31][32][33] • Reduced early diastolic endoepicardial and left ventricular free wall base-apex gradients • Increased end-diastolic endoepicardial and left ventricular free wall base-apex gradients • Increased radial and especially longitudinal IVRT In Maine Coon cats, heterozygous for the MyBPC3 mutation but free of LV hypertrophy, a significant decrease in E DTI /A DTI was demonstrated in the longitudinal movement of the basal interventricular septum (in comparison to wild homozygous animals).…”

“…Systolic dysfunction is also present in HCM, often initially characterized by radial hyperkinesia (with increased systolic velocities and gradients), followed by a decrease in longitudinal ventricular systolic velocities (radial systolic velocities being, at this stage, often normal or reduced) [29,31]. An S′ wave corresponding to a postsystolic contraction is noted in almost 25% of feline HCM cases, particularly for the left and/or right septal longitudinal movement [29].…”

Myocardial Tissue Doppler, Derived Techniques, and Speckle Tracking Imaging

“…In a normal cat, for example, the early diastolic velocities of the interventricular septum are higher than those of the left ventricular free wall [29]. Similarly, in a dog, the right longitudinal velocities are higher than those of the left ventricular free wall, at both the base and the apex [28].…”

Advanced Echocardiographic Techniques in Small Animal Practice

“…A large amount of data is available in the human medical literature regarding the use of TDI for the evaluation of overall cardiac function. In veterinary medicine, PW and M-mode TDI have been employed for evaluation of both the diastolic and systolic function in healthy cats and in cats with hypertrophic and unclassified cardiomyopathy (Gavaghan et al, 1999;Koffas et al, 2003Koffas et al, , 2006. The vast majority of colour 2D TDI studies in small animals has been carried out by French researchers.…”