• Digital subtraction angiography (DSA) is a fluoroscopic technique used for visualizing the vascular system. Structures such as bones are digitally subtracted from the image, which allows a better depiction of the blood vessels
  • Seldinger method is used for access to the vessels
  • the vessel is punctured with a hollow needle
  • a soft curved tip guidewire is inserted through the needle and positioned into the vessel lumen
  • a guidewire is held while the needle is carefully removed
  • the large catheter is threaded over the guidewire into the vessel lumen
  • the guidewire is removed
  • sheath now serves as a route for diagnostic catheters and other medical devices
Digital subtraction angiography (DSA)

Indications

Acute and elective therapeutic endovascular procedures

Carotid angioplasty followed by stenting
Embolization of direct arteriovenous fistula
SOLITAIRE - successful recanalization of M1 occlusion

Diagnosis of cerebral vascular diseases

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Functional tests

  • balloon test occlusion (BTO) – assesses whether an artery can be temporarily/permanently closed without significantly affecting brain perfusion
  • Wada test – short-term blockade of the function of a specific part of the brain after a selective intra-arterial administration of a short-acting barbiturate. It helps to establish which hemisphere controls language function and how important each hemisphere is regarding memory functions

Detection of circulatory arrest in brain death diagnosis

→  see Brain death diagnosis chapter

Contraindications

Most contraindications are relative ⇒ assess risk-benefit

  • contrast agent-related contraindications
    • renal insufficiency (the results of the laboratory tests must be obtained prior to the examination)
      • eGFR should be > 30 mL/min in patients receiving iodinated contrast
      • discretion should be used in patients with eGFR < 45 mL/min
    • hypersensitivity to iodinated contrast agents (contrast dye)
      • reactions to contrast media are not a true allergy but a pseudoallergy in nature (there are no allergic antibodies present)
      • the contrast media cause mast cells to release histamine and other chemicals directly
      • the contrast agent concentration affects the severity of an adverse reaction ⇒ higher concentration = greater risk of an adverse reaction
      • severe, life-threatening reactions, including anaphylaxis, occur in approx. 0.1% of people receiving contrast agent
  • pregnancy (relative contraindication with acute therapeutic procedures)
  • blood clotting disorders and use of anticoagulant drugs
  • unstable cardiopulmonary/neurological status

Procedure

Preprocedural evaluation

  • check:
    • personal medical history (presence of atherosclerotic disease, diabetes, renal dysfunction, etc.)
    • allergies and previous exposure to iodinated contrast media
    • prior vascular procedures
    • review relevant vascular imaging studies (CTA, MRA, neurosonology)
  • the patient should be fasting (> 4h, except for acute interventions)
  • secure adequate hydration  (nephropathy prevention)
  • in diabetic patients, do not administer peroral antidiabetics (metformin) in the morning
  • insert an intravenous cannula and urinary catheter
  • patient must sign an informed consent form after being fully informed about the procedure and its risks

Principles of contrast agent administration and allergy premedication

→ administration of an iodinated contrast agent

Monitoring during examination

  • the angio suite should be equipped with a monitor and crash cart
  • standard monitoring during diagnostic DSA
    • heart rate
    • blood oxygenation (pulse oximetry)
    • blood pressure (intermittently via a self-inflating cuff)
  • an anesthesiologist should be available if sedation or general anesthesia (GA) is demanded

Procedural technique

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Postprocedural care

  • bed rest for at least 4-6 h in the supine position
  • careful compression and monitoring of the puncture site and peripheral blood supply
  • blood pressure monitoring
  • adequate hydration

Complications

  • risk of a permanent neurological deficit following diagnostic DSA is low (0.09-0.14%)
  • increased risk is associated with endovascular procedures (thrombectomy, coiling, stenting, etc.)

 local and systemic complications of endovascular procedures

Artery perforation during mechanical thrombectomy
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Digital subtraction angiography (DSA)
link: https://www.stroke-manual.com/digital-subtraction-angiography-dsa/