[Abdominal Doppler echography. Pathologic arterial signals].

In this paper, the features are reported of the major pathological flow signals obtained during Doppler examinations of abdominal vessels. The patterns are correlated with the pathological lesions which may cause them, as well as with the underlying changes in arterial hemodynamics. Pathological flow signals are divided into three groups, according to the sites where the lesions producing them are located. a) Lesions of the vessel walls. In this group, both widening of spectrum due to disturbed flow and increased blood velocity from vessel stenosis are presented. Also flow alterations occurring in aneurysms (reduction of flow velocity and presence of vorticous flow) are discussed. b) Changes in peripheral resistances. Peripheral resistances may either increase or decrease due to a variety of diseases. Parenchymal edema, compression, infiltration, as well as small vessel disease, may increase vascular impedance. Fall of vascular resistances may be observed in inflammation or in arteriovenous fistulas either large (congenital or hemodialysis fistulas) or microscopic, as in many hypervascular tumors. A typical "to and fro" flow pattern was seen in vessels where flow resistance is overcome only during systole, such as in arterial pseudoaneurysms. c) Changes in rhythm or strength of the heartbeat, cardiac valvular diseases, postocclusive flow. A variety of pathological findings may be observed in these conditions. Peculiar changes in the waveforms are seen with variations in heart frequency. Changes may be detected also in aortic valvular diseases, with retrograde flow observed in patients with aortic insufficiency. Low and slow flow are seen in post-stenotic and/or postocclusive vessels.