12. Angiography and Vascular Interventional Radiology Flashcards
What is DSA?
- digital subtraction angiography
- a pre-contrast image is taken and then subtracted from the post-contrast image
- bones and other radio-opaque structures are part of the “Mask” image, which is subtracted
What are some image guided arterial interventions?
- embolization for active bleeding
- angioplasty for arterial stenosis
- arteriovenous malformation sclerotherapy
What are the sites of vascular access?
- common femoral artery: retrograde and antegrade
- brachial artery
- radial artery (can be done in out-patient setting)
US guidance can be used for arterial puncture especially in case of weak palpable pulses, obesity or challenging anatomy
What is the Seldinger-technique?
technique for vascular access (venous and arterial)
- percutaneous puncture of blood vessel with a hollow needle
- guidewire is introduced through the needle
- needle is removed and compression over the guidewire prevents bleeding
- angiographic catheter is the advanced into the vessel using the guidewire
Arterial accesses for femoro-popliteal interventions
- contralateral common femoral artery (retrograde)
- antegrade, ipsilateral common femoral artery
- ipsilateral popliteal retrograde
arterial accesses need to be planned precisely in advance; considering all variations, occlusions or stenoses
Central venous access
- for intervention or placement of catheter for pharmaceutical treatment
- usually the catheter is placed into the internal jugular vein using US guidance
What is PTA?
- percutaneous transluminal angioplasty
- guidewire (needs to get through the lesion) is used to insert a balloon or stent, which is then inflated/expanded
- the size of the balloon/stent is crucial to avoid any arterial rupture
What is subintimal angioplasty?
- when the guidewire cannot pass through the lumen it is introduced between the tunica intima and media
- from distal to the pathological segment it reaches the true lumen again
What are the indications for EVAR?
- EVAR: aortic aneurysm endovascular repair
- asymptomatic and has >5.5cm diameter
- symptomatic regardless of size
- known impending rupture
What are the indications for thrombolysis?
- acute lower limb ischemia (avoid amputation)
- acute/chronic vascular occlusion
- mortality rate is similar to surgical mortality rate but surgery has better outcome
What are the contraindications and complications of thrombolysis?
- complication: bleeding can be fatal
- contraindications: intracranial/GI bleeding in history, upcoming surgery in 6 wks
What are the drugs used for thrombolysis?
- urokinase
- recombinant human tissue type plasminogen activator (tPA)
What are the indications for embolization?
- tumor
- bleeding
- malformation, A-V fistula
Embolization of pseudoaneurysm
- thrombin is commonly used, especially around the groin area after common femoral artery puncture
- US guided
- 90% success rate
What is transarterial chemoembolization?
- chemo combined with embolization materials
- effectiveness is enhanced with low systemic side-effects since concentration in the tumor itself is high
- palliative therapy for unresectable hepatocellular carcinoma and as a bridge to liver transplant
