Nontraumatic vascular emergencies: imaging and intervention in acute venous occlusion |
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Authors: | Haage Patrick Krings Timo Schmitz-Rode Thomas |
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Institution: | (1) Department of Diagnostic Radiology, University of Technology Aachen, Pauwelsstrasse 30, 52057 Aachen, Germany,;(2) Department of Neuroradiology, University of Technology Aachen, Pauwelsstrasse 30, 52057 Aachen, Germany, |
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Abstract: | Risk factors for acute venous occlusion range from prolonged immobilization to hypercoagulability syndromes, trauma, and
malignancy. The aim of this review article is to illustrate the different imaging options for the diagnosis of acute venous
occlusion and to assess the value of interventional strategies for venous thrombosis treatment in an emergency setting.
First, diagnosis and treatment of the most common form of venous occlusion, at the level of the lower extremities, is presented,
followed by pelvic vein and inferior vena cava occlusion, mesenteric venous thrombosis, upper extremity occlusion, acute cerebral
vein thrombosis, and finally acute venous occlusion of hemodialysis access.
In acute venous occlusion of the lower extremity phlebography is still the reference gold standard. Presently, duplex ultrasound
with manual compression is the most sensitive and specific noninvasive test. Limitations of ultrasonography include isolated
distal calf vein occlusion, obesity, and patients with lower extremity edema. If sonography is nondiagnostic, venography should
be considered. Magnetic resonance venography can differentiate an acute occlusion from chronic thrombus, but because of its
high cost and limited availability, it is not yet used for the routine diagnosis of lower extremity venous occlusion only.
Regarding interventional treatment, catheter-directed thrombolysis can be applied to dissolve thrombus in charily selected
patients with symptomatic occlusion and no contraindications to therapy.
Acute occlusion of the pelvic veins and the inferior vena cava, often due to extension from the femoropopliteal system, represents
a major risk for pulmonary embolism. Color flow Doppler imaging is often limited owing to obesity and bowel gas. Venography
has long been considered the gold standard for identifying proximal venous occlusion. Both CT scanning and MR imaging, however,
can even more accurately diagnose acute pelvis vein or inferior vena cava occlusion. MRI is preferred because it is noninvasive,
does not require contrast agent, carries no exposure to ionizing radiation, and is highly accurate and reproducible. Apart
from catheter-directed thrombolysis, mechanical thrombectomy has proven to be a quick and safe treatment modality by enabling
the recanalization of thrombotic occlusions in conjunction with minimal invasiveness and a low bleeding risk. Mechanical thrombectomy
devices should only be used in conjunction with a temporary cava filter.
Contrast-enhanced CT is at present considered the examination of choice for acute mesenteric vein occlusion which has mortality
rates as high as 80%. Patients with proven acute mesenteric venous occlusion and contraindications to surgical therapy and
no identified bleeding disposition without looming bowel ischemia or infarction are possible contenders to the less invasive
percutaneous approach either by (in)direct thrombolysis or mechanical means.
Ultrasonography is the primary imaging modality for the diagnosis of upper extremity thrombosis. Computed tomography and
MRI are in addition helpful in diagnosing central chest vein occlusions. The interventionalist is rarely involved in the treatment
of this entity. Catheter-directed thrombolysis is known to improve lysis rates. Together with balloon angioplasty good results
have been obtained. If stenosis or thrombus remains after thrombolysis and angioplasty, stent placement should follow.
Within the first two weeks, thrombosed dural sinus and cerebral venous vessels are typically hyperdense on CT compared with
brain parenchyma; after the course of 2 weeks, the thrombus will become isodense. In MRI an axial fluid-attenuated inversion
recovery sequence, an axial diffusion-weighted MRI, coronal T1-weighted spin-echo and T2-weighted turbo-spin-echo sequences,
a coronal gradient-echo and a 3D phase-contrast venous angiogram should be performed. Local thrombolysis is needed only when
patients have an exacerbation of clinical symptoms or imaging signs of worsening disease despite sufficient anticoagulation
therapy.
Acute occlusions of dialysis grafts and fistulae are a frequently encountered complication. Among the various methods described
for acute occlusion screening, ultrasonography and MRI have been proven to be accurate and noninvasive; however, if immediate
treatment can be anticipated, imaging should be performed directly by digital subtraction angiography before the percutaneous
intervention. Initial percutaneous thrombectomy is very effective with success rates and patency rates comparable to those
of surgical thrombectomy. A short thrombosis can be treated with balloon angioplasty alone, whereas an extensive thrombosis
requires a combination of mechanical devices and/or thrombolytic agents with adjunctive balloon angioplasty.
Electronic Publication |
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Keywords: | Veins Thrombosis Transluminal angioplasty Stents Prostheses Thrombectomy Thrombolysis Dialysis Shunts |
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