LVOT obstruction in a cat

This 6 year old female cat was referred for echo due to an incidental finding of a heart murmur.

Her heart walls were very hypertrophied, and there was turbulence in her outflow tract.

parasternal long-axis


parasternal long-axis




There was also mild posteriorly directed mitral regurgitation, likely functional – this means it is not caused by a problem with the valve itself, but due to the way the valve apparatus is dragged into the left ventricular outflow tract during systole.


In a case like this, if you have a phased array probe then it’s really important to obtain the left apical view in order to confirm the suspected outflow tract obstruction using your continuous wave Doppler. The clip below is a modified four chamber view in order to catch the mitral regurgitation, but the turbulent flow in the outflow tract can be seen again to the left.


Note: Scale should always be optimised to fit the entire waveform. Annoyingly, the Siui Apogee high frequency phased array probe has a maximum velocity limit of 5.5m/s. The gradient generated through this cat’s outflow tract was so unusually high as to actually exceed the maximum velocity on the scale. In this instance I could have switched to the lower frequency phased array probe to obtain a full trace, but the cat was becoming agitated at this point and we already had a diagnosis.

CW traceCW trace