Exploration of the abdominal arteries and veins may be technically challenging but it also reveals valuable information about the blood flow patterns present in normal vessels and those with pathology. While B-mode imaging demonstrates the morphology of vessel walls and lumens, spectral, color and power Doppler imaging detail the presence, location and severity of disease. Evaluation of the hepato-portal system provides information on blood flow patterns through the arteries, veins and collateral network that supply and drain the liver in the normal patient and those with hepato-portal dysfunction. Interrogation of the mesenteric system in the pre and post-prandial patient reveals the fascinating changes in Doppler spectral patterns that occur with alterations in flow demand in response to the metabolic demands associated with digestion. Renal duplex studies provide an opportunity to experience changes in blood flow patterns that occur not only with stenosis and occlusion of the renal artery and its branches but also with changes in vascular resistance of the end –organ. As with the circulatory systems in other areas of the body, B-Mode imaging of the abdominal vessels complemented with analysis of the Doppler spectral waveforms yields valuable clues to the detection and classification of vascular disorders.
Dazoxiben, a specific thromboxane synthetase inhibitor, was evaluated in 21 patients with Raynaud's phenomenon in a double-blind, placebo-controlled crossover experiment. Total fingertip blood flows were measured by plethysmography and capillary blood flows were measured by 133Xe disappearance rate. Subjects were studied in both a warm (28°) and a cold (20°) room. Arteriovenous (AV) shunt flow was estimated by subtraction of capillary flow from total flow. Ex vivo production of thromboxane B2 (TXB2) and 6-keto PGF1α was determined by specific radioimmunoassay in serum from venous blood incubated for 1 hr (37°). Plasma concentrations of TXB2 and 6-keto PGF1α were also monitored. Dazoxiben (100 mg 4 times a day for 14 days) inhibited ex vivo TXB2 production (from 463.1 ± 69.9 to 101.8 ± 13.4 ng/ml/hr; (X̄ ± SE)), enhanced ex vivo 6-keto PGF1α production (from 1.38 ± 0.05 to 3.76 ± 0.18 ng/ml/hr), reduced plasma TXB2 concentration (from 88.1 ± 13.9 to 38.8 ± 5.9 pg/ml). There were no changes in plasma concentration of 6-keto PGF1α. Dazoxiben did not improve total digital blood flow, capillary flow, AV shunt flow, or forearm blood flow at 28° or 20°. There was no subjective improvement in frequency or severity of Raynaud's attacks (assessed by patient diaries). It is concluded that dazoxiben is a potent and specific thromboxane synthetase inhibitor capable of altering arachidonic acid metabolism, but is of little or no benefit in the treatment of Raynaud's phenomenon. Clinical Pharmacology and Therapeutics (1984) 36, 105–115; doi:10.1038/clpt.1984.147
The selective use of endovascular devices to repair abdominal aortic aneurysms was introduced in the early 1990s. Although placement of an aortic endograft offers patients a less morbid alternative to surgical repair, this procedure is not without complications. Persistent perfusion of the residual aneurysmal sac via endoleaks may place the patient at risk for aneurysmal enlargement and subsequent rupture. Historically, serial computed tomographic angiography has been used as the primary modality for assessment of aortic endografts. In recent years, sonography has been shown to provide a valued tool for ongoing surveillance of aortic endografts and identification of endoleaks, increasing aneurysmal size, hemodynamic disorders, and graft migration and/or kinking. Standardization of the sonographic evaluation yields accurate information vital to the long-term patency of these conduits.
This expert consensus statement on the interpretation of peripheral arterial and venous spectral Doppler waveforms was jointly commissioned by the Society for Vascular Medicine (SVM) and the Society for Vascular Ultrasound (SVU). The consensus statement proposes a standardized nomenclature for arterial and venous spectral Doppler waveforms using a framework of key major descriptors and additional modifier terms. These key major descriptors and additional modifier terms are presented alongside representative Doppler waveforms, and nomenclature tables provide context by listing previous alternate terms to be replaced by the new major descriptors and modifiers. Finally, the document reviews Doppler waveform alterations with physiologic changes and disease states, provides optimization techniques for waveform acquisition and display, and provides practical guidance for incorporating the proposed nomenclature into the final interpretation report.
