Introduction to Angiography

Radiographic visualisation of blood vessels after the injection of contrast.

The Resultant image is called an angiogram

Used to diagnose:

Stenosis- Narrowing or blood vessel

Occlusion- blocked or closed blood vessel

Dilation- Abnormally wide vessel

It is important to image blood vessels as tissues and organs need a constant blood supply and if compromised could lead to unviable tissues or organs.

Endovascular procedure- takes place within the vessel.

• Pt changes into gown, underwear is removed
• They are placed supine on the table and attached to monitoring.
• Access is required and the area must be shaved, groin.
• Skin is cleaned, and prepared, drapes
• Inject local anaesthetic.
• Use ultrasound to locate blood vessel for access
• Arterial needle is introduced directly into the artery.
• Guidewire is inserted through the needle.
• Needle is withdrawn and guidewire is left in situ.
• Guidewire is threaded through vessels to the affected area under fluoroscopic control.
• Catheter is threaded over the top of the guidewire
• Contrast is injected through the catheter whilst live screening to identify areas that are narrowed. This is called a run
• Interventioncan then be undertaken, i.e. Angioplasty.
• Angiogram performed again to determine if intervention has worked.
• Catherter is removed
• Pressure is applied

DSA- Digital Subtraction Angiogram, Compares a pre contrast, with a post contrast image. The contrast then subtracts the common elements to both. Prevents images of objects like bones from obscuring vascular details.

Roadmap- A feature used to assist with passing catheters and guide wires trough structures and to avoid branch vessels. Contrast injected and image subtracted, Image inverted so contrast appears white, Fluoro activated and guidewire will appear superimposed onto inverted image.

Continuous fluoroscopy- Tube emits a continuous flow of x-rays. This produces the best image quality.

Pulsed Fluoroscopy- Tube emits a series of short pulses rather than continuously, less ideal  quality but much lower dose.

Last image hold- Allows the last image to be digitally frozen on the monitor after the x-ray exposure has been terminated.

Guidewires- Allows safe introduction of catheter into the vessel. Stored in plastic.

Guidewire characteristics- Pushability, steerability, Torque, Opacity

Guidewire type- non-steerable, for catheter positioning, steerable, for narrow stenosis or tortuous anatomy.

Angioplasty balloon

Stent

Stent graft

Screening tests:

• Full blood count
• Serum Creatinine
• eGFR
• INR
• MRSA

Consent:

• Voluntary , informed and capacity
• Verbal explanation and pt information leaflets

Medical history:

• High risk patients, Previous reactions diabetics, renal failure, pregnancy

• Haemorrage
• Embolus formation
• Vasospasm
• Infection risk
• Contrast reactions

On the day:

• Nil by mouth
• Change pt in gown
• Explanation of procedure, consent
• pt lies supine
• pt monitoring attached
• Cannula sited
• Sedation

• Compression
• Bed rest for 4 hrs
• Observations
• Discharge home- no driving, plenty of fluid, know how to puncture site, follow up appointments.

• Record DAP
• Patient ID
• Minimise number of frames
• Justification of examination
• Last image hold
• New technology
• <aximise distance between pt and tube
• Pregnancy status
• Vary C-arm
• Pulsed Fluoro
• 5 Min timer
• Explanation of procedure
• QA Equipment
• Minimise distance between pt and image receptor
• Collimation
• Exposure factors
• Avoid magnification
• Operator training