Assessment of the Repeatability of Feline Echocardiography Using Conventional Echocardiography and Spectral Pulse‐wave Doppler Tissue Imaging Techniques

Abstract

The objective of this study was to determine the intraoperator, intraobserver, and interobserver repeatability in a series of conventional echocardiographic parameters and in some of the newer measurements of diastolic function, including color M-mode flow propagation velocity, isovolumic relaxation time and pulsed-wave Doppler tissue imaging velocities. Four healthy cats were each scanned five times over a 3-day period. The repeatability of these echocardiographic analyses was compared using Bland-Altman analysis (intraoperator repeatability). After a minimum of 5 weeks, one scan was randomly selected from each cat, and was remeasured by the original observer and the results compared using a standard paired Student's t-test (intraobserver repeatability). One scan from each cat was then randomly selected and two observers, with similar levels of experience, measured each of these scans. The repeatability of these echocardiographic analyses was compared using Bland-Altman analysis (interobserver repeatability). The conventional two-dimensional (2D), M-mode and spectral Doppler measurements were repeatable in both their acquisition and measurement by a single investigator; there was a greater degree of variation between the two observers. The predominant (S', E', and A') pulsed-wave Doppler tissue imaging velocities from the left apical four-chambered view, generally had a coefficient of variation of approximately 20% (range 9.62-34.08%). However, with pulsed-wave Doppler tissue imaging, velocities recorded during the isovolumic phases, the velocity of the tricuspid annulus, and the radial fiber velocity within the interventricular septum, frequently had coefficients of variation in excess of 20% and should therefore be interpreted with caution.

Echocardiographic evaluation including tissue Doppler imaging in New Zealand white rabbits sedated with ketamine and midazolam

“…Finally, we did not evaluate intra-operator variability. Poor repeatability has been reported in the acquisition of the velocities from the long-axis posterior wall and interventricular septum using pulsed TDI analysis (Simpson et al, 2007). Another study showed that the intra-examination variability was better under anaesthetised conditions (Chetboul et al, 2004), which was attributed to perfect immobility of the animal that improved repeatability of TDI measurements.…”

Feline hypertrophic cardiomyopathy: an echocardiographic approach

“…Spectral pulsed-wave TDI is a technique that measures myocardial velocity, which has good temporal resolution (Simpson et al 2007) and has been used to assess the velocities within the feline myocardium (Chetboul et Chetboul et al (2006a) using affected cats and carriers of dystrophin-deficient hypertrophic muscular dystrophy as a model of HCM, demonstrated that TDI could detect radial and longitudinal LVFW dysfunction in all cats even though none of the animals presented significant left myocardial hypertrophy. In this same study, those cats with mutations but without LVFW hypertrophy showed larger longitudinal TDI isovolumic relaxation times, longitudinal TDI E'/A' ratios less than 1 at the base and radial TDI E'/A' ratios less than 1 in the sub-endocardium and subepicardium, as well as reduction of systolic longitudinal myocardial velocities at the heart base and apex, when compared with healthy cats.…”

“…The TDI is an echocardiographic technique that allows quantification of global and regional myocardial function from measurements of myocardial velocities in real time (Chetboul 2002, Simpson et al 2007, Chetboul 2010. Pulsed-wave and colour M-mode are TDI techniques that have been demonstrated to be sensitive tools to detect even mild forms of HCM, providing an early diagnosis of the disease (MacDonald et al 2006, Koffas et al 2006, Koffas et al 2008.…”

“…Left ventricular outflow tract, valve flows and myocardium velocity can be examined by using Doppler studies (colour, continuous and pulsed wave and TDI) (Boon 2011). The left apical four-chamber view can be used to assess trans-mitral (figure 1) and trans-tricuspid flow patterns, while the left apical five-chamber view could be used to obtain the aortic flow velocity (Simpson et al 2007, Fuentes 2010, Boon 2011.…”

“…The 2D and M-mode diastolic measurements must be analysed at end-diastole, which can be identified by the beginning of the QRS complex (Simpson et al 2007, Boon 2011. Images of papillary muscle, mitral valve, aortic root and LA should be obtained by means of 2D and M-mode techniques.…”