Fig. 2

The four different blood flow profiles of the interdigital artery in the pastern region distal to the convergence of the dorsal metatarsal artery III with the dorsal common digital artery III. The image on top shows the interdigital artery in sagittal section and brightness mode. Below is the pulsed wave Doppler curve. a Type 1. The blood flow profile is biphasic without reverse blood flow, and the maximum diastolic velocity is at least half of the maximum systolic velocity. b Type 2. The blood flow profile is biphasic without reverse blood flow, and the maximum diastolic velocity is between one fourth and one third of the maximum systolic velocity. c Type 3. The blood flow profile is biphasic without reverse blood flow, and the blood flow velocity approaches the zero line between the maximum systolic and the maximum diastolic velocities. d Type 4. The blood flow profile is characterised by a triphasic waveform with one episode of reverse blood flow. IA = interdigital artery, V = dorsal common digital vein III, a = maximum systolic velocity (Vsyst), b = maximum diastolic velocity (Vdiast), c = end-diastolic velocity (Venddiast), d = reverse velocity (Vrev)