Chapter 23 Fundameltals of Interventional Radiology and Interventional Endoscopy Flashcards
How is interventional radiology defined?
The use of contemporary imaging modalities to gain access to different structures throughout the body to deliver therapeutic materials for a variety of conditions
What are the recommended cystoscope diameters when performing rigid cystoscopy in female animals
1.9 - 6.5mm
List three functions of channel in cystoscope
Fluid irrigation, fluid drainiange and working channel
What size of flexible scopes are used in male dog for cystoscopy?
2.5 - 2.8m diameter, 1mm diameter working channel
What are the differences between seldinger vs modified seldinger technique
Seldinger = two wall punture + needle with outer cannula
Modified seldinger - one wall punture and needle only
N.B. In practice at QMHA we do combo of both i.e. use needle with catheter but only punture one wall of vessel.
Define ‘gague”
Number of needles/catheters that can be placed next to each othe within 1 inch.
What are the diameter and length of available veterinary guide wires?
How does introducer sheat measurement differ
0.038 - 0.14 inch diameter, 150 - 300 cm in length
Gague of introducer sheath refers to inner diameter
What does 3 Fr equate to in mm?
3 Fr = 1 mm
i.e.
9 Fr = 3 mm
List 3 advantages of an introducer sheath
- Allow safe, controlled, confluent dialtion of vessel
- Protection from damage
- Prevent haemorrhage (check flow diaphragm prevents back flow)
Name the three types of guide wire in picture and list + describe a 4th type
A, Marker pigtail catheter. Note the radiopaque markers on the shaft, as well as the multiple fenestrations permitting rapid contrast injection without fear of damage to the vessel wall, compared with the end-hole catheter.
B, Rim (reverse-curve) catheter ideal for access from one external iliac artery to the ipsilateral internal iliac or contralateral external or internal iliac arteries.
C, Cobra-type catheter with gentle bend facilitating access into first-order arterial branches off the aorta or vena cava.
Also Hockey stick/”Berenstein”
List the two types of balloon cathteter and their uses
Low pressure occlusion balloon: For temporary occlusion of a vessel to facilitate angiography or redirect embolization
Balloon angioplasty catheters: For dilation of stricutures. Baloon folled with contrast
List the 3 factors by which stents are classified
Metallic vs non-metallic
Self expanding vs balloon expandable
Covered vs uncovered
Name the 5 types of stent in image
A, Stainless steel mesh SEMS (Wallstent, Boston Scientific), and
B, nitinol mesh SEMS (Vet Stent-Trachea, Infiniti Medical LLC).
C, Nitinol laser-cut SEMS (Vet Stent-Urethra, Infiniti Medical LLC).
D, Silicone-covered nitinol mesh stent graft (Vet Stent, Infiniti Medical LLC).
E, Polyester-covered mesh stent graft (Wallgraft, Boston Scientific).
List the three types of self-expanding metallci stents
Mesh: most common, reconstrainable, foreshortening
Woven/braided: thinner gague so softer, non-reconstrainable, minor foreshortening. No real advantage over mesh so not routinely used in veterinary
Laser cut: non-reconstrainable, minimal foreshortening. Used in urethra and vasculature but high fracture rate in trachea
List 4 disadvantages of covered stents
- Increased cost
- Increased implanted material
- Increased migration rates
- Larger delivery system
List 3 disadvantages of balloon expandable stents
- Short lengths available
- Poor flexibility
- Static response to compression (i.e if compressed does not re-expand).
Balloon expandable typically reserved for nasopharyngeal stenosis
List 3 factors used to classify embolics
Mechanical vs particulate
Temporary/biodegradable vs permanent
Solid vs liquid
Name the embolics in image:
A, Amplatz canine ductal occluder (ACDO) for embolization of patent ductus arteriosus (ACDO, Infiniti Medical LLC).
B and C Vascular plugs in side (B) and front (C) projections. Note fine nitinol woven pattern and screw in site for guide wire, permitting repositioning and removal if necessary.
D, Thrombogenic coils in delivery system and deployed (center). Note thrombogenic Dacron (=inflammatory polyester) fibers (white) surrounding the metal core.
List the most commonly used permanent particulate embolic agent
Polyvinyl alcohol particles/hydrogel microspheres
What is the most common liquid embolic. How is radio-opacity achieved?
N-butyle cyanoacrylate glue (NBCA). Polymerizes into a solid once in contact with an ionic substance
Usually mixed with ethiodized oil (=Lipiodol = iodinated poppy seed oil) in 1:1 to 1:4 ratio depending on desired rate of polymerization. Radio-opaque, enhanced by addition of tantalum
What is the most common biodegradable embolic?
Gelatin sponge, lasts days to weeks.
At what wavelenght does diode laser emit light?
980 nm
–> simultaneous absorbtion in water and Hb therefore cutting and coagulating. Main cutting property is buy thermal energy
What does Ho:YAG laser stand for?
At what wavelength does it emit light?
To what depth does it work?
Ho:YAG = Holmium: Yttrium, Aluminum, Garnet
LASER = light amplification by stimulated emission of radiation
Emits light at 2100 nm
Absorbed in <0.5mm fluid (i.e. v little depth!) therefore good for endourologic use i.e. usually used for lithotripsy
List three properties of iohexol
Low osmolarity
Non-ionic
Iodinated
N.B. Barium = ionic
List 5 possible side effects of contrast administration
Nausea
Vomiting
Pain
Anaphylaxis
Nephrotoxicity
