(II) Indications [2]
Intra cranial
I.
Nontraumatic subarachnoid haemorrhage or SAH of unknown aetiology.
II.
Acute stroke
III.
Nontraumatic parenchymal cerebral haemorrhage
IV.
Intracranial aneurysm: To study cross flow/ complex aneurysm anatomy
V.
Cerebral vasospasm
VI.
Mass lesions: Preoperative tumour embolization,
eg.
meningioma,
cavernous sinus haemangioma.
VII.
Intracranial arteriovenous malformations to classify (Speltzer Martin score) and plan intervention
VIII.
Dural arterio-venous fistulas
IX.
WADA test
Extra cranial
I. Extracranial carotid stenosis
II. Carotid blowout
III. Subclavian steal
IV. Cervical trauma
V. Epistaxis
VI.
Preoperative tumour embolization Juvenile nasopharyngeal angiofibroma (JNA).
(III) Contra indications:
No absolute contra indications.
Relative contraindications
Contrast allergy:
Remedy à
Standard prophylaxis using Methylprednisolone,
12 and 2 hours before the procedure.
Low Osmolar Contrast Media (LOCM) and judicious use of iodinated contrast.
Pre- and post procedure hydration with normal saline.
Renal insufficiency: Dialysis pre and post procedure,
if dialysis dependent.
Coagulopathy: Should be corrected when possible
(IV) Patient preparation [2,
3]
Pre-procedural work up
Informed consent should be taken from the patient.
Focused history with physical exam (with neurological examination).
Review of available imaging to assess arch anatomy or variants that may aid in catheter selection in case of vessel tortuosity/ atherosclerotic disease.
Laboratory parameters:
Complete blood cell count – to assess the haemoglobin status and rule out acute sepsis.
Serum creatinine or Glomerular filtration rate (GFR): for baseline record of renal status and to rule out renal dysfunction.
PT/ INR to rule out coagulopathy.
Anticoagulants should be withheld when possible.
Nil per oral for at least 6 hours pre-procedure.
The morning insulin dose should be reduced in half.
Bilateral inguinal regions and/ or the left arm (radial/ brachial access) should be prepared and made sterile depending on the case.
An immediate pre-sedation/ anesthesia neurological status assessment should be performed and documented.
Sedation and positioning
Sedation with intravenous midazolam and analgesia with fentanyl is used in our center.
Patients should be positioned supine with a headrest and arms are placed beside the body in extension with support.
Uncooperative patients may need to have their head gently taped to reduce motion.
Instructions should indicate patients to stay motionless,
especially during image acquisition,
and also be told about a potential sensation of warmth within the head with each injection and to avoid swallowing when imaging the neck vasculature,
both aimed to reduce motion related artefact.
(V) Technique [2,
3]
Access
Right common femoral artery (CFA) is preferred for intra-arterial access.
When CFA access is not optimal,
brachial artery access maybe required.
Micropuncture systems with or without ultrasound guidance vs standard 18 G access needles can be used for arterial puncture and a j-wire (atraumatic curved tip) is used,
over which the arterial sheath is advanced.
(Figure 5)
5-F arterial sheath is placed insitu with a continuous heparinized saline sheath infusion to prevent peri sheath clotting.
Catheterization
· Catheters used: (Figure 5)
Most often used is the 5F vertebral (angled) catheter for normal proximal vessels.
Judkin’s Right coronary catheter for old age and tortuous vessels.
Simmon’s catheter or Mani’s Head Hunter catheter for extremely tortuous arch vessels.
· Wires:
Hydrophilic 0.035-inch wire such as Glidewire (Terumo)
· Precautions:
I.
“Double flush technique” à minimize unintended air or blood clot embolus.
II.
“Wet connect”à while connecting syringe to catheter or saline drip to sheath.
This is to also prevent inadvertent air embolus.
III. Tactile feedback with smooth motion on advancing wire is essential to rule out dissection / vessel perforation.
IV.
Catheter should be always advanced over the wire,
which forms support system.
Torqueing motion of the catheter on wire during advancing is useful.
V.
Road maps of the vascular anatomy should be obtained prior to crossing any vessel bifurcation,
especially in cases with difficult anatomy.
This aids in preventing ostial dissections.
VI.
After advancing the catheter,
as the wire is removed,
an inadvertent vacuum effect in case the catheter tip is wedged against the vessel wall,
thus sucking in air into the catheter.
To prevent air embolization,
remove the guidewire slowly,
keeping the catheter hub filled with heparinized saline by dripping it into the hub while the wire is withdrawn.
This also aids in wet connect with the syringe after the wire is completely withdrawn.
VII.
Prior to injection,
there should be flow back from the catheter,
to rule out catheter tip wedging / dissection / intra catheter clotting.
VIII.
Extra care should be taken when selective angiogram of the vertebral artery is done,
as it is prone to complications like dissection to vasospasm.
Delayed or incomplete contrast washout indicated possibility of vasospasm or dissection.
Angiographic views [2] (Table 1)
· Cervical arch angiogram: especially if there is suspicion of diseased arch vessel origins (eg.
Atherosclerotic narrowing of the ostium) or variant/ difficult to catheterize anatomy (eg bovine arch).
The catheter of choice is a multiside -holed flush/ pigtail catheter.
The injection rate is typically 20 mL/s,
and the duration of injection is 2 seconds for a total of 40mL of contrast.Cervical aortic arch is performed approximately 35-degree left anterior oblique position to assess the great vessel origins in profile.
· For extracranial carotid arteriography,
anteroposterior (AP),
lateral,
and 45-degree bilateral oblique projections are standard.
The injection rate is 4 to 5mL/s for total of 7 to 9mL,
and the image frame rate is 2 to 3 f/s.
· For anterior intra cranial cerebral angiography,
AP (Townes view) and lateral projections are standard.
One helpful tip is to position the petrous bones at the level of the mid to lower orbits as a guide.
The injection rate is 4 to 5 mL/s for 20 to 25 mL total,
and the image frame rate is 2 f/s.
· For vertebral arteriograms,
the standard projections are AP (Townes view) and lateral projections centered caudally.
and dorsally to cover the posterior circulation.
In distinction to the anterior circulation,
the petrous bones should be projected at the bottom or below the orbits to best visualize the basilar artery and its branches in the AP dimension.
The injection rate is 5 to 7 mL/s for total of 8 to 10 mL total,
and image frame rate is 2 f/s.
Post procedure care [2,
3]
CFA access care: Haemostasis maybe accomplished with manual compression or a percutaneous closure device.
Groin hematoma should be looked for during ICU monitoring.
Puncture site vessels should be immobilized for at least 24 hours post puncture.
Post procedural neurological examination should be performed and any new neurological deficits should be documented.
Significant neurological changes may require further evaluation with magnetic resonance imaging or repeat DSA to rule out acute stroke / vessel dissection etc.
Two hours monitoring in ICU is part of out institution protocol.
Oral analgesics (Paracetamol) could be administered in case of puncture site pain.
(VI) Complications and remedies
Most common complication is groin hematoma,
seen in around 4 % cases.
Neurologic complications within 24hrs (Transient ischemic attack) in 2.5% cases.
Stroke with permanent focal neurological defect in 0.1% and death in 0.06%.
Predictors of complications:
Patient related:
Sub arachnoid haemorrhage evaluation.
Atherosclerotic cerebro-vascular disease
Frequent Transient ischemic attacks
Age > 55years
Diabetes,
especially if poorly controlled.
Procedure related:
Increase in length of the procedure
Increased number of catheter exchanges
Larger size of catheters
(VII) Reporting essentials:
I. At least two views: Antero Posterior and Lateral (± Oblique / Specific views)
II. Two systems: Anterior and Posterior circulations.
III. Three phases: Arterial,
Capillary (or parenchymal) and Venous phases.
IV. Variant anatomy to be addressed.
V. Collaterals à Primary (From ACOM and PCOM) and Secondary (pial-pial and leptomeningeal- dural); Compression studies to assess collateral status.
VI. Shifting,
Distortion or Herniation of the vessels.
VII. Lesion à tumour or vascular : description,
type etc.
(VIII) Case examples.
(Figure 6 - 20)
We have included various common case examples where DSA is useful in the diagnostic evaluation,
followed by interventional treatment.