Assessment of Left Ventricular Systolic Function by Strain Imaging Echocardiography in Various Stages of Feline Hypertrophic Cardiomyopathy

Abstract

Background: Diastolic dysfunction occurs in many cats with hypertrophic cardiomyopathy (HCM). Less is known about systolic function in various stages of HCM. Myocardial strain analysis by tissue Doppler imaging (TDI) is a noninvasive echocardiographic method to assess systolic function that has not been reported previously in cats.Objectives: To evaluate systolic function in various stages of feline HCM by measurement of myocardial strain. Animals: Two hundred and sixty-three cats. Methods: Cats were classified by echocardiography into one of the following groups: clinically healthy (control) group (n 5 160), mild HCM (n 5 22), moderate HCM (n 5 39), and severe HCM (n 5 42). Peak myocardial strain, measured by TDI in the basal and midventricular segment of the interventricular septal wall (IVS) and the left ventricular posterior wall (LVPW), was compared among different HCM and control groups.Results: Whereas conventional echocardiography demonstrated an apparently normal or supernormal contractile state based on percentage of fractional shortening, myocardial strain in all HCM groups was significantly decreased compared with the control group (P o .001). There was a significant correlation between strain values and wall thickness (P o .001). Reproducibility of strain analysis was 6.3% in the IVS and 9.7% in the LVPW.Conclusions and Clinical Importance: Myocardial strain analysis is a new, valuable, and reproducible method in cats. This method allows noninvasive detection of abnormal systolic deformation in cats with HCM despite apparently normal left ventricular systolic function as assessed by conventional echocardiography. The abnormal systolic deformation already was present in mild HCM and increased with progressive left ventricular concentric hypertrophy.

Feline hypertrophic cardiomyopathy: an echocardiographic approach

“…Finally, assessment of RV morphology and function is very difficult in M-mode studies (Ferasin 2009). Some clinical investigations of feline HCM have used an end-diastolic wall thickness equal to or exceeding 6.0 mm as the primary diagnostic criterion (Koffas et al 2008, Wess et al 2010. However, another study adopted 5.0 mm as a decision criterion (Brizard et al 2009) (figure 2).…”

“…Other techniques include St and StR, and these measurements were introduced into clinical practice to evaluate regional myocardial deformation magnitudes and rates (Wess et al 2010). The term St is related to a decrease or increase in the length of a myocardial segment.…”

“…These measurements, primarily of the papillary muscles, left ventricular wall and interventricular septum (IVS), are very useful for diagnosis of hypertrophy (Bonagura 2000), and an inadequate position of leaflets can be observed at the mitral valve level (Fox et al 1995). End-diastolic wall thickness of the IVS and the left ventricular posterior wall (LVPW) must be measured in the basal and mid-ventricular segment of the respective myocardial wall using the right parasternal long-axis view (Wess et al 2010) or right short-axis view (Fox et al 1995). The LA must be interrogated for increased diameter, and attention must be given to the presence of thrombi using 2D measurements (Bonagura 2000).…”

“…Definitive diagnosis of feline HCM is mainly based on echocardiography, which is the method of choice to observe structural changes and evaluate pathological dysfunctions (Brizard et al 2009, Wess et al 2010. Studies have demonstrated that HCM was the most frequent alteration observed during echocardiography examination conducted in apparently healthy cats (Paige et al 2009, Nakamura et al 2011.…”

“…Studies have demonstrated that HCM was the most frequent alteration observed during echocardiography examination conducted in apparently healthy cats (Paige et al 2009, Nakamura et al 2011. Regarding this tool, a large number of echocardiographic methods are used in feline cardiac diseases (Bonagura 2000), such as conventional echocardiography (M-mode, two-dimensional and classic Doppler as spectral and colour flow) and new Doppler techniques (tissue, strain and strain rate) (Abbott and MacLean 2006, Wess et al 2010, Boon 2011.…”