Editing Angiogram


== Preparation ==

* Review imaging/previous angiograms
* Hb and eGFR
* Consent
* Orientation of room
* Level of sedation
** GA required for unco-operative patient, unable to lie flat, difficult to access artery

== Therapeutic technique ==

* Balloon angioplasty
** Mechanism: blunt dehiscence leading to fracture and separation of the intima from the media, with stretching of media and adventitia
** Types of systems:
*** Over-the-wire
**** Wire passes through the entire catheter
**** Good support, high pushabiity
**** Allows for guidewire exchange when a lesion is difficult to cross
*** Single-operator exchange aka monorail or rapid exchange
**** Wire enters from the distal tip of the catheter and exits from a side-hole 20-25cm proximal to the balloon
**** Used in coronary interventions and for below-knee lesions
**** Easier to use because a single person can deliver and exchange it close to the insertion point
** Balloon characteristics
*** Compliance - degree of expansile ability - function of pressure and diameter
**** Compliant balloons are superior in trackability and suitable for lesions in a curved part of the vessel. Not suitable for severely calcific lesions as it may damage the adjacent normal vessel.
**** Non-compliant balloons aka high-pressure or low compliance balloons. Allow for high-pressure expansion and have a higher RBP than compliant balloons.
**** Nominal pressure - the pressure at which the balloon expands to its determined diameter and length, generally 3-10 atmospheres
**** Rated burst pressure is the pressure at which <1% of tested balloons will burst, but beyond which the probability of rupture increases, typically 6-16 atmospheres
**** Mean burst pressure - pressure at which 50% of balloons will rupture - usually 10-27 atmospheres
*** Profile and balloon ability
**** Profile - French size - smaller profile is better than a larger in terms of deliverability to the lesion and the ability to cross severely stenotic lesions
**** Trackability - ability to follow guidewire without loss of wire position, which is important when following a tortuous vessel
**** Pushability - ability to transmit force along the length of the balloon catheter to the target lesions. Better with larger balloons and OTW systems. 
**** Crossability - ability to cross stenotic lesions - depends on tip features and low-friction systems
*** Types of balloons
**** Cutting balloons - 3 or 4 artherotomes mounted longitudinally along the surface of a standard PTA balloon
**** Cryoplasty - uses cooling and pressure to dilate the plaque and the vessel wall
**** Focal pressure balloon
**** Drug coated balloon
***** Adopts the technology from DES
***** Coated with anti-proliferative drugs such as paclitaxel
***** Favourable outcomes in terms of lumen size and long-term patency compared to standard balloons, but really long-term data are lacking
***** Perform pre-dilation with a standard balloon before using DCB
** Technique:
*** Mostly done with 6Fr access
*** Systemic heparinisation - 50-100U/kg prior
*** Pass the wire through the lesion via the true lumen
**** Use a 0.035 hydrophilic wire for most lesions
**** 0.018 for highly stenotic lesions
*** Balloon selection
**** Balloons are available up to 30cm in length
**** Mostly start off with an undersized balloon then work up to target size
****
*** Balloon placement - re-DSA the lesion just prior to balloon placement
*** Difficulty during balloon passage
**** Exchange the wire for a stiffer wire
**** Advance the sheath or guide catheter closer to the lesion
**** Switch to a lower-profile balloon or one with greater pushability
*** Balloon inflation
**** Ensure it is flushed prior to insertion
**** Replace the existing air inside the balloon with 25-50% contrast
**** Most severe stenotic lesion should be in the middle of the balloon
**** Monitor balloon shape in real time with fluoroscopy
**** Typically keep inflated for 30-60 seconds
**** Risk of rupture if patient complains of severe pain during expansion - maintain position across the lesion in case stenting is required
*** Completion angiography
** Complications
*** Dissection

''Grade A is a small radiolucent area within the lumen of the''

''vessel disappearing with the passage of the contrast material.''

''Grade B is a filling defect parallel to the lumen of the vessel''

''disappearing with the passage of contrast material. Grade C is''

''a dissection protruding inside the lumen of the vessel persisting''

''after passage of contrast material. Grade D is a spiral-shaped''

''filling defect with delayed run-off of the contrast material in''

''the distal vessel. Grade E is a persistent luminal filling defect''

''with delayed antegrade flow. Grade F is a filling defect accompanied''

''by total occlusion. Stenting is typically required with''

''Grade C to F dissections.''

* Stents
** Mechanism: useful in reducing the incidence of restenosis or address balloon PTA failure due to elastic recoil or dissection
** Mostly based on nitinol - an alloy of nickel and titanium
** Types:
*** Balloon-expanding (BES)
**** Balloon is inflated to deploy the stent
**** Suitable only for vessels that are not prone to external compression (become irreversibly deformed) - avoid in ICA or SFA
**** Can be placed more precisely than SES
**** Tend to be more radio-opaque than SES
**** Good for renal, mesenteric, iliac, subclavian, or brachiocephalic arteries
*** Self-expanding
**** Mostly nitinol
**** More flexible - greater trackability, and resistant to fracture
**** Less likely to cause interference on MRI
**** Most stents are stored in the delivery sheath, and deployed from the distal end to the proximal end by unsheathing, and generally can't be repositioned after that
**** Generally OTW systems
**** Classified as open-cell (cylindrical structure of stacked serrated metal) or closed-cell (all edges and vertices of the stent cells are shared with an adjacent cell - preferable for lesions at risk of embolisation because the mesh is very fine) design
*** Bare metal
**** Mostly stainless steel/nitinol/cobalt chrome or other alloys
*** Covered
**** Can be PTFE, polyurethane, or silicon
*** Stent grafts
**** Balloon-expanding or self-expanding
**** Stent struts with something like PTFE shell
**** Can be used for perforations or for various occlusive lesions
*** Drug-eluting stents
** Complications:
*** In-stent restenosis
*** Stent fractures


== Atherectomy devices ==

* Ideally achieve patency without the need for stenting - especially useful for areas where stenting should be avoided (CFA, POPA behind knee)
* Types:
** Direction
*** Carbide cutting blade with a variable height and a plunger used to pack the atheroma into the nose cone
*** Cutting blade rotates at up to 8000rpm
*** Designed for treating severe calcification
** Rotational
*** Insert a small drill into the artery to fracture a plaque and create a smooth lumen
** Laser atherectomy

Thromboembolectomy

* Aspiration
** Simplest way to remove thrombus - aspirate it with a large catheter or sheath (Export, PriorityOne, Pronto)
** Risk of distal embolisation remains - thrombolytic drugs often used in combination
** Work better in smaller vessels (<6mm)
* Rheolytic
** Jet of saline ejected from the tip of the catheter and used to dissolve it
* Rotational
** Remove the thrombus by rotating the tip of the catheter

Intra-luminal devices to cross chronic total occlusions

* Can be difficult or impossible to cross the plaque or segment of poorly organised thrombus, which often has a fibrotic or calcified cap at both ends, due to an inability to generate enough axial force through the guidewire
* Devices such as Crosser, TruePath, Frontrunner XP can be used to assist

Re-entry devices

* Outback LTD Re-Entry System - penetrates the intimal flap, redirecting the guidewire from the subintimal plane to the true lumen
* Other devices for similar effects

Embolisation devices

* Used to treat bleeding, small aneurysms, fistulas or endoleaks
* Mechanical
** Coils
** Vascular plugs
* Particulates
** Polyvinyl alcohol
** Gelatin microspheres
* Liquid agents
** Absolute ethanol
** N-butyl cyanoacrylate

== Vascular closure devices ==

* So far demonstrated to be non-inferior to manual compression
* AngioSeal - sandwiches the arteriotomy with a bioabsorbable anchor connected with sutures and a collagen sponge that dissolve within 60-90 days. Compatimble with 5-8Fr sheaths.
* Exoseal - bioabsorbable polyglycolic acid to achieve haemostasis. Compatible with 5-7Fr.
* Mynx - polyethylene glycol sealant deployed outside the artery, while a small balloon inflates the arteriotomy site to create temporary haemostasis within the artery. 5-7Fr.
* ProGlide - suture-based - mimics open surgical closure. 5-21Fr.
* Prostar XL - for large bore device closures.

[[Category:Vascular]]