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.

Clinical toxoplasmosis is commonly reported in the cat, with the most consistent findings being ocular, pulmonic, hepatic, neurological, gastrointestinal and muscular abnormalities. Myocarditis, whilst frequently identified at post-mortem examination, has not been identified ante-mortem. In immunocompromised humans, myocarditis associated with toxoplasmosis is not an uncommon complication. In such cases, lymphocytic myocardial infiltration can lead to depressed myocardial function, which can be associated with congestive heart failure, rhythm disturbances and pericardial effusions. In addition, myocardial failure has been reported in immunocompetent humans associated with active toxoplasmosis [Chandenier J, Jarry G, Nassif D, Douadi Y, Paris L, Thulliez P, Bourges-Petit E, Raccurt C (2000) Congestive heart failure and myocarditis after seroconversion for toxoplasmosis in two immunocompetent patients. European Journal of Clinical Microbiological Infectious Disease 19, 375-379]. Here we describe a cat with echocardiographic changes consistent with infiltrative or inflammatory disease, and elevated IgG and IgM titres to Toxoplasma gondii. There was resolution of these myocardial changes once the toxoplasmosis was treated.

The identification and assessment of myocardial failure in canine idiopathic dilated cardiomyopathy (DCM) is achieved using a variety of two-dimensional and Doppler echocardiographic techniques. More recently, the availability of tissue Doppler imaging (TDI) has raised the potential for development of new ways of more accurately identifying a disease phenotype. Nevertheless, TDI has not been universally adapted to veterinary clinical cardiology primarily because of the lack of information on its utility in diagnosis. We assessed the application of timing of left heart base descent using TDI in the identification of differences between DCM and normal dogs. The times from the onset of the QRS complex on a simultaneously recorded electrocardiograph to the onset (Q--S'), peak (Q--peak S'), and end (Q--end S') of the systolic velocity peak were measured in the interventricular septum (IVS) and the left ventricular free wall. The duration of S' was also calculated. The Q--S' (FW), Q--end S' (FW), and duration S' (FW) were correlated with ejection fraction in the diseased group (P < 0.05). In addition, Q--S', Q--peak S', Q--end S', and the peak S' velocity were prolonged in the diseased dogs at both the free wall and in the IVS (P < 0.01). The duration of S' was unaffected by disease status. These findings provide insight into the electromechanical uncoupling that occurs in canine DCM and identifies new TDI parameters that can be added to the range of Doppler and echocardiographic parameters used for detecting myocardial failure in the dog.