angiography & vascular interventional radiology Flashcards
Seldinger technique: tools
- puncture needle: 18G (one-part or two-part)
- guidewire: atraumatic, non-thrombogen, torque control, hydrophilic coating (for difficult cases), variable diameter (0.014-0.038)
- diagnostic catheters: braided plastic tube, flexible, kink-resistant, torque response, outer diameter is measured in French scale - 1F = 1/3 mm
non-selective (flush) Vs selective angiography
selective has improved image quality, uses less contrast medium, has increased risk of complications.
puncture sites
- femoral: retrograde, anterograde, bilateral
- brachial
- radial
- popliteal
possible complications
- at the puncture site:
- bleeding, hematoma
- pseudoaneurysm
- AV fistula
- occlusion - embolisation
- selective carotid angiography: 0.1-0.3% risk for stroke
- non-selective arch aortography: 0% risk - dissection
closure devices
used for large puncture sites, especially in highly anticoagulated patients.
- Angio-Seal: absorbable collagen sponge, absorbable polymer anchor connected by an absorbable self-tightening suture.
arterial interventions
- percutaneous transluminal angioplasty (PTA), stent implantation
- stent-grafts (TAA and AAA) & covered stents
- thrombolysis, aspiration, thrombectomy devices
- embolisation (tumors, AVM, fibroif (UFE), bronchial artery, GI bleeding, bleeding from tumors, trauma, iatrogenic)
- dialysis fistulae managements (declotting, PTA)
percutaneous transluminal angioplasty (PTA)
- lower limb, subclavian, renal, aorta, mesenteric, carotid bifurcation, proximal CCA, innominate, coronary
- special balloons: cutting balloon, cryotherapy
- stent types: balloon-mounted, selfexoandable, drug-eluting
venous procedures/interventions
- PTA/stent, TIPS
- varicocele embolisation
- radiofrequency or laser ablation of varicose veins
- IVC filter placement and retrieval
- venous access, chronic venous lines (Hickman line)
- foreign body retrieval
- venous sampling
what to do before getting access
- examination of the patient
- patient history, previous interventions, operations
- pulse palpation
- laboratory values
- risk/benefit ratio
- consenting the patient
- plan the whole procedure
advantages of interventional radiological procedures over surgery
- local anesthetics - no complications from general anesthesia
- no surgical dissections (no wound infections, no nerve injury, no suture insufficiency)
- small amount of blood loss
- minor burden for the patient / can be performed on severely ill patients
- following unsuccessful intervention, surgery is still an option
- can be repeated numerous times
disadvantages of interventional radiological procedures over surgery
- not all surgical procedures can be substituted by an interventional procedure
- interventional radiological procedures are also not free of complication
stent types
- balloon mounted:
- premounted, stainless steel
- easy positioning
- rigid (external compression)
- not comformable for different diameters (eg. carotid bifurcation) - self-expandable - nitinol (nickel-titanium alloy):
- continuous expanding force
- conforms to different diameters
- positioning is less precise
- shortening - larger diameter, decreased length
PAD - peripheral arterial disease
- largest component to the workload
- most patients are chronic:
a. asymptomatic
b. intermittent claudication (IC)
c. critical limb ischemia (CLI)
non-surgical treatment for PAD
- IC patients:
- exercise
- smoking cessation
- aspirin
- clopidogrel - CLI patients:
- antiplatelet therapy
- prostanoids (PGE1, Iloprost)
percutaneous transluminal renal angioplasty (PTRA) - indications
- severe hypertension resistant to full medical treatment
- ACE-inhibitor induced uraemia
- deteriorating renal function
- flush pulmonary edema
- acute renal failure with a good sized kidney
- severe stenosis in a single functioning kidney
carotid artery stenting CAS - indications
- used to decrease the risk of ipsilateral embolic stroke *
- symptomatic patients within 6 months; patients with symptoms within 4 weeks benefit most ( >70% diameter stenosis)
possible symptoms: hemisymptoms, amaurosis fugax, aphasia - periprocedure complication rate should be < 3%, otherwise the pt does not benefit from CAS/CEA (carotid endarterectomy)
CAS - relative indications
- asymptomatic, with:
- > 90% diameter stenosis
- > 80% stenosis and ipsilateral silent ischemia on CT
- rapid progression of carotid stenosis
- > 90% diameter stenosis and contralateral occlusion
- periprocedure complication rate should be < 3%, otherwise the pt does not benefit
stent graft - covered stent: indications
- aneurysms
- traumatic lesions
- to decrease the risk of re-stenosis
- to decrease the risk of distal embolisation
abdominal aortic aneurysm (AAA)
- focal widening > 3cm
- normal size of abdominal aorta (> 50 y.o.): ~ 2 cm
- prevalence: increases with age, greater with atherosclerotic disease
- male predominance
- whites:blacks = 3:1
- risk factors: male, age > 75, white, prior vascular disease, HTN, smoking, family history, hypercholesterolemia
- 30% asymptomatic
- 26% abdominal mass
- 37% abdominal pain
- location: 91-95% infrarenal with extension into iliac arteries (66-70%)
intraarterial thrombolytic therapy
- Intravascular administration of thrombolytic agents -> for pulmonary embolism
- Thrombolysis by means of selective catheter infusion -> for vascular occlusion
- also for: treatment of thrombus and/or thrombosis in the coronary arteries, peripheral vascular and visceral arteries, dialysis grafts, veins, and IV catheters.
thrombolysis
1) Urokinase: 2-chain Ser protease, that contains 411 am. ac/s. Like streptokinase, it lacks fibrin specificity and induces a systemic lytic state. Urokinase is typically given with full heparinisation (aPTT 1.5-2 times control values). Titration o the dose of heparin is often difficult to achieve.
2) recombinant human tissue-type plasminogen activator (tPA): Ser protease that is produced by recombinant DNA technology. Chemically identical to human endogenous tPA. Acts by stimulating fibrinolysis of blood thrombi.
indications of thrombolysis
- acute and chronic vascular occlusion
- thromboembolus
- native bypass graft occlusions
- acute lower-limb ischemia -> prevention of amputation
contraindications of thrombolysis
- intracranial or GI hemorrhage in patient history
- any operation within 6 weeks
relative contraindications of thrombolysis
- coagulopathy
- gastric/duodenal ulcer
- liver disease, portal HTN
- extreme HTN
- gravidity
- ICU care not possible
- lack of cooperation of the patient
complications of thrombolysis
bleeding - may be fatal
- GI: 5-10%
- puncture site: 12-17%
- hemorrhagic stroke: 1-3%
materials used for embolisation
- coils
- PVA particles
- lipiodol
- alcohol
- tissue glue (cyanoacrilate)
- thrombin (for pesudoaneurysms)
uterine fibroid embolisation (UFE)
Indications: symptomatic leiomyoma
“ideal” candidate for UFE:
- symptomatic premenopausal women
- single or multifibroid uterus
- in whom surgery is indicated
- who does not desire to preserve fertility
- who prefers minimal invasive treatment
venous access - methods
- chronic infusion catheters
- peripherally inserted central infusion catheters (PICC)
- ports
- alternative vascular access techniques
chronic infusion catheters
a) temporary (non-tunneled):
- no precise definition for time
- planned duration more than 6 weeks is considered long-term
- exit ports in close proximity to the venous puncture site
b) long-term (tunneled): Indications: - chemotherapy - long-term nutrition (TPN) - antibiotic treatment - hemodialysis - plasmapheresis
insertion techniques for venous access / chronic
1) right (or left) IJV:
- most common
- higher success rate
- lower complication rate
- US guidance
2) subclavian vein:
- infraclavicular or
- supraclavicular -> rare, more risky
3) femoral vein:
- easiest
- highest incidence of complications
- infection & thrombosis
possible complications of venous access
1) immediate:
- PTX
- great vessel puncture or perforation
- air embolism
- catheter malposition
2) delayed:
- infection
- venous stenosis
- fibrin sheath & thrombus formation
IVC filter insertion - absolute indications
- DVT:
- contraindication for anticoagulation
- recurrent thromboembolic disease, despite anticoagulation therapy
- significant complication of anticoagulation therapy
- inability to achieve adequate anticoagulation (despite patient compliance)
