ANALYSIS OFMURMUR INTENSITY, DURATION AND FREQUENCY COMPONENTS IN DOGS WITH AORTIC-STENOSIS

A study was undertaken to investigate the relationship between murmur intensity, murmur duration, duration to peak intensity and frequency c omponents with degree of aortic stenosis in boxers. Measurements were made from phonocardiograms obtained from 35 boxers with ejection-type murmurs, and values were compared with those obtained for aortic flow velocity measured by Doppler echocardiography, Murmur intensity graded by auscultation was significantly correlated with aortic flow velocit y (P<0.001), and murmur duration, expressed as a percentage of systole , was significantly correlated with aortic flow velocity (P<0.001), in dependent of heart rate, Dogs with early systolic murmurs not exceedin g 50 per cent of systole had aortic flow velocities of less than 1.5 m /second and no echocardiographic abnormalities, in contrast with dogs with murmurs of longer duration. Dogs with only high frequency compone nts had lower aortic velocities than those that also had components in the medium frequency range (P<0.01).