Tardus parvus

Tardus parvus refers to a pattern of Doppler ultrasound spectral waveform resulting from arterial stenosis. The phenomenon is observed downstream to the site of stenosis, and is due to reduced magnitude of blood flow through the narrowed vessel during ventricular systole .

This characteristic pattern is useful in assessing for renal artery stenosis. The pattern can also be seen distal to other sites of arterial stenosis (e.g. hepatic arterial stenosis), as well as within collateral vessels following an arterial occlusion .

Radiographic features

• tardus: prolonged systolic acceleration (i.e. slow upstroke)
• parvus: small systolic amplitude and rounding of systolic peak