* Ar wave velocity may be increased with adequate left atrial function, or reduced with severe atrial dysfunction.
* Ar wave velocity may be increased with adequate left atrial function, or reduced with severe atrial dysfunction.
* If the Ar wave duration exceeds the mitral A wave duration, this is evidence of increased left sided filling pressure.
* If the Ar wave duration exceeds the mitral A wave duration, this is evidence of increased left sided filling pressure.
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====Tissue Doppler Imaging (TDI)====
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This is a relatively recent technique in cats which is used to evaluate the speed of longitudinal movement of the myocardial walls during the different phases of the cardiac cycle. In normal cats, three waves can be identified:
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* Positive '''systolic wave (Sm)'''
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* Negative '''early diastolic wave (Em)'''
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* Negative '''late diastolic wave (Am)'''
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In normal cats, the Em velocity is higher than the Am velocity. In cats with diastolic dysfunction and impaired ventricular relaxation (as in the case of RCM), The Em velocity may be markedly reduced. Note that impaired ventricular relaxation is also identified as a normal aging change in cats; therefore cautious interpretation is required with elderly cats.