Page 9 - Carotid and peripheral vascular interventions textbook
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                 STEP-BY-STEP TECHNIQUE                          and AV shunt vein is occasionally necessary to facilitate
                                                                 wire crossing and to achieve continuous monitoring of
                 PERIPROCEDURAL MEDICATION                       the stent implants in central veins. In tortuosity vessel

                                                                 and occlusion, stents also can be placed over a guide wire
                     The purpose of antithrombotic therapy for CVD   forming a loop through (‘body-f ossing’ technique or
                 angioplasty with or without stenting is to prevent stent   through-and-through technique) the AV shunt vein and
                 thrombosis and/or in-stent restenosis. Regardless of rising   femoral vein in order to provide support for the transvenous
                 rates of venous angioplasty and stent implantation, few   segment and possibly prevent stent embolization into the
                 studies have been conducted to predict the best antithrombotic    pulmonary circulation.
                 therapy regimen (47). Most current practices, based on      If patients don’t have an AV shunt vein, upper extremity
                 previous experience in managing CVD, rely on data   venography can be performed by using hand contrast
                 reported from arterial stent implantation. For patients   injection into the venous system via an 18- to 20-gauge
                 undergoing planned SVC, brachiocephalic or subclavian   needle or angiocath in the superf cial veins on the dorsum
                 venous intervention, we usually give 81 mg to 325 mg of   of the hand. With this technique, cephalic or basilic vein
                 aspirin and clopidogrel 75 mg daily prior to the procedure   can be located and punctured using a 4F-micropuncture
                 for 5-7 days. In case of untreated patients, a loading dose of   set or a radial set (as used for percutaneous coronary
                 clopidogrel 300-600 mg (4-8 tablets) and 81 mg of aspirin   intervention). Using a doppler ultrasound guidance is
                 are usually given before the procedure. Unfractionated   also helpful for getting vascular access of a non-palpable
                 heparin 50-70 units/kg with target activated clotting time   superf cial vein.
                 (ACT) 250-300 sec is administered. The use of thrombolytic
                 agents or glycoprotein IIb/IIa agents for central vein  DIAGNOSTIC CENTRAL VENOGRAPHY

                 obstruction is unnecessary and not recommended as an
                 initial treatment. Less data is available for the application      A diagnostic venogram can be performed through
                 of thrombolytic agents during central venous thrombosis   a venous access from the common femoral vein or the
                 (48). Therefore, it is not recommended as an initial treatment    arm or using a 6-Fr Judkins right (JR) or multipurpose
                 regimen. Catheter-based thrombolysis is effective for     (MP) catheter which is cannulated into the brachiocephalic
                 the treatment of central vein blockage secondary to acute   or subclavian vein. Digital subtraction central venography
                 thrombosis, particularly in combination with a staged   is well visualized in the anteroposterior (AP) projection.
                 surgical correction for the anatomical etiology for venous      For a short stenotic lesion, imaging evaluation is
                 constriction for the case of Paget-Schroetter syndrome.   mainly performed by venography via the dialysis access
                 (49,50).                                        and advancing a catheter up to the lesion to obtain
                                                                 imaging. Diagnostic DSA from the outf ow vein of the AV
                 VASCULAR ACCESS                                 access to the SVC is achieved (Fig. 14-5). This diagnostic
                                                                 imaging is used to def ne anatomy, pathology of CVD
                     Non-invasive pre-procedural imaging such as CTV   and collateral pathways. After venography, simple
                 or MRV, if available, is helpful to make a plan and choose   endovascular intervention can be performed through
                 an appropriate vascular access. A venous access can be   this arm access.                           435
                 obtained using surface or anatomic landmarks or imaging      In case of central venous occlusion, following primary
                 guidance, usually doppler ultrasound. In short lesions of   identif cation of the distal end of the lesion from the arm
                 the central veins, preferred access is usually from the arm   access, a second common femoral vein access usually
                 using the AV shunt vein. Percutaneous needle entry to the   is required and inserted with a 6-Fr JR4 or MP catheter
                 AV f stulas or grafts is straightforward, because these shunt   advanced up to the brachiocephalic occlusion lesion.
                 veins usually are engorged and felt of palpable thrill. In   Further venography by synchronous contrast injection
                 some cases, when large balloons or stent devices are used,   from both ends of the lesion is performed once more to
                 transfemoral venous access can be used to avoid injury of   delineate the position and length of the occluded segment
                 the AV shunt veins. In case of subclavian or brachiocephalic   and to characterize collaterals and the point at which the
                 vein occlusion, two-way approach via common femoral   central vein segment becomes patent again (Fig. 14-6).
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