Doppler echocardiography is a very useful and popular method of evaluating left ventricular systolic and diastolic function. In cats, the later has a major concern, as the type of cardiomyopathy may be defined according to the mitral flow pattern.
The purpose of this study is to determine values as: E and A waves velocities, E/A ratio, E wave deceleration time, and IVRT in healthy non-sedated cats, as well as correlate these indices to the heart rate.
The study group consisted of 40 healthy, adult cats housed in the cattery of the School of Veterinary Medicine of São Paulo University. Doppler examination was performed with the cats restrained in left lateral recumbency. Andersen-Darling test was used to test variables for normalcy. Mean, standard deviation and median were calculated for E wave velocity, A wave velocity, E wave deceleration time and IVRT. Pearson correlation was used to verify the influence of heart rate on E wave velocity, A wave velocity and IVRT, while Spearman correlation was used for E wave deceleration time x heart rate and E/A ratio x heart rate.
The mean value of peak early diastolic flow was 0.65 m/s, with a standard deviation of 0.13 m/s and median of 0.64 m/s (n=24); the mean value of the E wave deceleration time was 72.8 ms, with standard deviation of 9.4 ms and median of 75 ms (n=24); the mean value of the A wave was 0.45 m/s, with a standard deviation of 0.09 m/s and median of 0.46 m/s (n=24); the mean value of E/A ratio was 1.46, with standard deviation of 0.39 and median of 1,42 (n=24), and the mean value of the IVRT was 72.8 ms, with a standard deviation of 9.4 ms and median of 75 ms (n=40). Good correlation between heart rate and E wave velocity, E/A ratio and IVRT was observed, whereas E wave deceleration time and A wave velocity were not affected by the heart rate.
The establishment of these values will allow to define the pattern of the diastolic abnormality, usually related to cardiomyopathies in cats.
References
1. Bright, J.M.; Herrtage, M. E.; Schneider, J.F. Pulsed Doppler assessment of left ventricular diastolic function in normal and cardiomyopathic cats. J. Am. Anim. Hosp. Assoc., v. 35, p. 285-291, 1999.
2. Harrison, M. R.; Clifton, G. D.; Pennell, A. T.; Demaria, A. N.; Cater, A. Effect of heart rate on left ventricular diastolic transmitral flow velocity patterns assessed by doppler echocardiography in normal subjects. Am. J. Cardiol., v. 67, p. 622-627, 1991.
3. Nishimura, R. A.; Abel, M. D.; Hatle, L.K.; Tajik, A . J. Assessment of diastolic function of the heart: background and current applications of Doppler echocardiography. Part II: Clinical studies. Mayo Clin Proc., v. 64, p. 181-204, 1989b.