Editing Endovascular access (section)

== Technique ==

* Needles
** Single-wall: almost universally used for percutaneous access. 18-gauge needle for 0.035-inch guide wire. 21 gauge needle for 0.018-inch guide wire.
** Double-wall: blunt-tipped hollow needle with an inner bevelled stylet. Historically used to puncture both anterior and posterior walls, then inner stylet removed, then needle slowly withdrawn until blood comes back.
* Micropuncture needle technique
** Vessel identified with USS
** 21-gauge needle inserted at 30-45 degrees, so it enters the vessel at site of visualisation
** 0.018-inch floppy tip guidewire inserted into the vessel
** Needle removed from over the wire
** 4F introducer sheath
** Inner canula of sheath removed, along the guidewire
** 0.035-inch wire can be inserted at this point and sheath upsized to 5F or 6F if needed for definitive access
* Standard needle technique (for easily palpable femoral pulses in otherwise uncomplicated anatomy)
** 18-gauge needle and 0.035-inch J-tip moveable core steel guidewire (don't use hydrophilic-coated guidewire for initial entry as the coating can shear off and embolise from the needle)
** Straight to 5F or 6F sheath
** This technique is helpful in situations where tracking the 4F sheath over the less supportive 0.018-inch wire can be hard, like in scarred groins or when accessing a Dacron graft
* Sheaths
** Inside calibre measured by French size, from 4F to 11F
** Have a haemostatic valve at the end
** Braided sheaths can be used when cannulating a vessel through dense tissue or making sharp turns that can lead to kinking of the sheath
** Most commonly 10cm length for diagnostic purposes, but available 5-100cm
** 45cm sheath typically used working on the contralateral iliac system or beyond, and a 90cm sheath used to work on the carotids. Chosen sheath should be no longer than necessary.
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* Guidewires
** Jagwire (Boston Scientific) commonly used at Austin
*** Nitinol with Endo-Glide coating
*** 5cm hydrophilic tip
*** 0.025 or 0.035-inch diameters
*** 260 or 450cm length
*** Straight or angled tip
*** Good for use in biliary duct cannulation from top or bottom
* Catheters
** Vehicles used to deliver the radiographic contrast agent to the area of interest
** Most catheters 2F-6F
** 2F and 3F are microcatheters for delivery of embolisation coils
** Types of diagnostic catheters:
*** Non-selective - used to inject a high volume of contrast into relatively large blood vessels, typically using power injection. Multiple side holes along the last 15mm to reduce the 'jet effect'.
*** Selective - their shape facilitates engagement in the orifice of a branch vessel, for either direct injection or subsequent guidewire passage. Generally have an end hole only (no side-holes), and therefore can't inject with too much pressure. Divided into single-curved, double-curved and reverse-curved configurations.
**** Single-curved: ideal for cannulating a side branch vessel coming off at less than 45-degree angle from the aorta.
**** Double-curved: angle up to 90 degrees or greater.
**** Reverse-curved: typically have a 180-degree curve, for vessels that come off steeply.
** Interventional catheters:
*** Crossing 
**** Used for crossing occluded/stenotic vessels
*** Guiding catheters - essentially sheaths with tips with different lengths and shapes to permit selective cannulation
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* Closure devices
** Simple manual compression
*** Not too tight - lead to thrombosis
*** Hold for 5-20 minutes
*** 6 hours mandated bedrest
** Closure devices
*** Seal the access hole in some way or another
*** Minimise need for compression and bed rest
*** Increase risk of groin infection and leg ischaemia.
*** Angio-Seal - intra-arterial absorbable anchor is placed against an externally placed collagen sponge, and these are sandwiched together. Good for arteries >5mm without significant calcification, and can be used to close sites up 8F. Can get ischaemic complications when deployed incorrectly.
*** Mynx - polyethylene glycol polymer closes the tissue track over the puncture site, which dissolves within 30 days. Haemostasis for up to 6F. Higher risk of ischaemic and bleeding complications.
*** ProGlide - single polypropylene stitch to suture close arteriotomy sites up to 6F. Can be used off-label to close large arteries by putting two of them together. Device failure - manual compression, additional ProGlide use, or open repair.


Consent: bleeding, infection, thromboemboli, failure, additional procedures, contrast allergy or nephropathy, limb loss, anaesthetic, neurovascular