Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3860_Библиотеки_им_академика_М_И_Перельмана

against refluxing embolic material into the ICA circula­tion.

vessels with arterial feeders and enlarged draining veins. Although most of these lesions are intracranial, AVMs of the neck, scalp, and face do occur.

Refractory epistaxis is an important indication for angio­graphy. In most episodes of epistaxis, the bleeding point occurs in the anterior portion of the nasal cavity and is easily controlled by packing or cauterization. Bleeds that originate in the posterior or superior nasal cavity are more difficult to manage and often require posterior packs or ligation of the internal maxillary arter y. Poste­rior packs have a significant failure rate and are associ­ated with complications such as pressure-induced necro­sis and life-treatening hypoxia.

used when performing spinal angiography to avoid em­bolization or thrombosis of these vessels. There are no absolute contraindications to spinal angiography.

With the advent of multiplanar imaging, the role of angiography in pathological processes of the neck has diminished, although there are multiple indications for which angiography is still performed. It is routinely per­formed in conjunction with cerebral arteriography. Trauma to the neck in which vascular injury is suspected or cannot be excluded is a common indication for angiography. As previously noted, the percent of positive findings in patients stable enough to undergo angiogra­phy is low, and controversy exists as to whether angio­graphy should be performed unless there is a strong suspicion of vascular injury.

Recently, other imaging modalities have evolved that are able to assess the vascular structures in the neck, includ­ing duplex Doppler ultrasound, MRA, and computed tomographic angiography (CTA). Ultrasound is the most frequently used modality in the assessment of carotid disease and has the advantages of being noninvasive, easily tolerated, and relatively inexpensive. Its disadvan­tages include being operator dependent and, to a certain extent, anatomy dependent in that some vascular struc­tures are inaccessible and that heavily calcified or tortu­ous vessels may render the study difficult to interpret. MRA is noninvasive and less affected by vessel tortuosity or position, and multiplanar/three-dimensional recon­struction can be obtained. MRA shares the disadvantage of being adversely affected by heavily calcified vessel (field inhomogeneity effects) and being relatively expen­sive and susceptible to motion artifact. In addition, it is more difficult to monitor the patient while he or she is in the magnet. advent of spiral CT and fast computer reconstruction. The advantages of CTA include the ability to view the images in any plane, its relatively low cost, and minimal invasiveness. The disadvantages include long post­processing times, the necessity for iodinated contrast, and the fact that heavily calcified vessels significantly add to the difficulty of postprocessing, thus affecting the ac­curacy of the study. modalities, angiography is most accurate in the assess­ment of stenotic lesions. In a recent study, and MRA have been shown to have 65% and 52% exact correlation with angiography, respectively, with both mo­dalities tending to exaggerate stenoses. CTA has been shown to compare favorably with ultrasound and MRA, but it is not as accurate as angiography. with the superiority of angiography in the assessment of stenotic lesions as well as its versatility, it will continue to be performed until other modalities are proven superior or the discrepancy rates of these other modalities become insignificant compared with the complication rate of angiography.