i.e. this is your SVRI.
A loss of ventricular preload will also usually result in an increase in afterload (systemic resistance must rise to maintain a reasonable mean arterial pressure) – and so this is also a surrogate measure of left ventricular preload.
A shortened flow time will also occur with hypothermia and heart failure.
Like flow time, correlates with left ventricular afterload and preload. Not specific, and so not used very often.
... in the same way as stroke volume variation does
Obviously the left ventricle contractility needs to be good to generate a normal peak flow velocity. A diseased ventricle will generate crappy slow Vpeaks.