Page 7 - Carotid and peripheral vascular interventions textbook
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                 extrinsic  compression  of  mediastinal  veins  (e.g.,        Catheter-based central venography is typically done
                 mediastinal  f brosis,  lymphoma,  thoracic  aortic    as an initial procedure to an endovascular intervention.
                 aneurysm or goitre), should be considered.      DSA has more sensitivity than color duplex venous
                     The initial diagnostic study for CVD is color-f ow   ultrasound in the assessment of dialysis access with
                 duplex venous ultrasound as this technique is noninvasive   exceptional ability to discriminate central venous anatomy
                 with a high sensitivity and specif city (36). A normal vein is   from collateral veins. The 2019 Kidney Diease Outcomes
                 completely compressible on ultrasound. Non compressible   Quality Initiative (DOQI) guidelines also recommend
                 vein with loss of respiratory variations, polyphasic atrial   venography before implantation of a permanent AV access
                 waves, and no doppler f ow augmentation during interrogation     in previous subclavian catheterization patients (39).
                 indicate obstruction downstream of the probe. In addition,
                 the existence of many neck collaterals generally indicates  TREATMENT

                 CVD. A limitation of this technique is potential acoustic
                 shadowing from the clavicle, which may impair visualization       Treatment options applied for CVD rely upon the
                 of a short segment of the subclavian vein. It can also be   etiology of the disease. Current treatment options include
                 problematic to visualize central veins using ultrasound in   medical therapy, endovascular intervention and open
                 signif cant muscle mass or obese patients.      surgery (i.e., vein bypass). Raising the upper limb and
                     Computed tomography venography (CTV) and    adjunctive anticoagulant treatment may often mitigate
                 magnetic resonance venography (MRV) are increasingly   edema correlated with CVD, particularly when it is involved
                 utilized alternatives to x-ray contrast venography (37,38),   with acute thrombus. However, those measures, are not
                 which is still the gold standard for diagnosing CVD.     applicable in chronic blockage. The use of anticoagulants
                 MRV  is  useful  in  patients  with  advanced  chronic    alone has no function in the recanalizing process as the
                 kidney disease to avoid radiocontrast and to preserve     problem remains with the progression of scar tissue. Open
                 renal function or in those with radiocontrast allergy. CTV is    surgical techniques are limited to a few highly morbid
                 equal to digital subtraction angiography (DSA) (Fig. 14-4)   operations, including open endovenectomy, and venous
                 while more capable for assessing central veins proximal   bypass of the blocked central veins via sternotomy.
                 to long segmental obstruction at the level of the f rst rib      Endovascular intervention is the gold standard
                 or to detect a position-dependent blockage (37).   for treating CVD hemodialysis patients. The treatment


                 Figure 14-4. Computed tomography venography (CTV) of patients in f gure 14-3 showing right subclavian vein occlusion (white arrow).
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