IR Flashcards

1
Q

Which needle is smaller: 8G it 18G?

A

18G (smaller the gauge, bigger the needle)

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2
Q

Which catheter is bigger: 6F or 8F?

A

8F (bigger the French, bigger the catheter)

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3
Q

What does the gauge of a needle refer to?

A

The outer diameter of the needle

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4
Q

What does the French of a catheter refer to?

A

The outer diameter

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5
Q

What does the French of a dilator refer to?

A

The outer diameter

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6
Q

What does the french of a sheath refer to?

A

The inner lumen diameter (an 8F catheter is the largest that will fit in an 8F sheath)

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7
Q

What is the standard size of a guide wire used in IR?

A

0.035 inch

Note: Microwires are usually 0.018 or 0.014 inch.

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8
Q

What is a glide wire?

A

A hydrophilic wire that is used to pass through occlusions, stenoses, or small/tortuous vessels

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9
Q

1 mm = ? Inch

A

1 mm = 0.039 inch

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10
Q

1 mm = ? French

A

3F

Note: To get the diameter in mm, divide the French by 3.

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11
Q

How can you convert from French to mm?

A

Divide by 3

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12
Q

What is the minimum size catheter needed to fit a standard 0.035 inch wire?

A

4F

Note: A 4F catheter has an outer diameter of 4F (you just need to memorize that this will have the minimum inner diameter to fit a 0.035 mm wire). Don’t try to convert.

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13
Q

How large will the puncture site be if you use an 8F catheter?

A

8F (catheters are sized by outer diameter)

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14
Q

How big will the puncture site be if you use an 8F sheath?

A

10F (sheaths are sized by inner lumen diameter)

Note: You can get the outer lumen diameter by adding 2F.

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15
Q

1 French = ? Mm

A

0.33 mm

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16
Q

What unit is usually used for wire length?

A

Cm

Note; Inches are usually used for wire diameter.

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17
Q

How many mm will the puncture site of a 6F sheath be?

A

8F/3 = 2.7 mm

Note: The outer diameter of a sheath is 2F larger than the inner diameter.

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18
Q

What is the minimum mm that a puncture site be if you use a 6F sheath that is coaxially placed into a short access sheath?

A

10F/3 = 3.3 mm

Note: A 6F sheath has an outer diameter of 8F, so the minimum 8F short access sheath would have an outer diameter of 10F.

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19
Q

A 3F catheter is about as wide as a ___ Gauge needle

A

20G

Note: Both of these are approximately 1 mm.

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20
Q

What is the standard sized puncture needle used in IR (without a micro puncture)?

A

19G (to allow passage of a 0.035 inch wire)

Note: 19G is the outer diameter (just memorize this).

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21
Q

What is the micro puncture technique?

A

Using a smaller initial puncture and micro wire to gain access, then dilating up:

  1. Initial puncture with a 21G needle (rather than the larger standard 19G)
  2. Place 0.018 inch microwire and withdraw needle
  3. Use dilator(s) to increase size to 4F or 5F (which will allow a standard 0.035 inch wire)
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22
Q

What are non-steerable wires used for?

A

Support for exchanging catheters (NOT for navigating vessels)

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23
Q

What is a standard wire length?

A

180 cm

Note: A long wire is usually ~260 cm.

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24
Q

When would you use a long wire?

A
  • When you’re using a long guide catheter (>90 cm)
  • When you’re working far from the puncture site (I.e. upper extremity from a femoral access)
25
Q

What is the benefit of a floppy tipped wire?

A

The longer the floppy tip, the less likely you are to dissect a vessel

Note: Choose the longest floppy tip available for navigation (might need a shorter floppy tip if you have to push through a tight spot/occlusion.

26
Q

What is the least stiff guidewire?

A

Bentsen

27
Q

What is the most stiff guidewire?

A

Lunderquist (mostly used for aortic stent grafting)

Note: Amplatzer is also very stiff.

28
Q

What guidewire can you use to test whether an acute thrombus is amenable to lysis?

A

Bentson

29
Q

Which guidewire should you choose is you’re trying to get into a tight spot?

A

Hydrophilic

Note: Bentson is also an option.

30
Q

Which is more likely to cause a dissection: Bentson or Amplatzer?

A

Amplatzer (the stiffer the wire, the more likely it is to dissect)

31
Q

How do you minimize the risk of a stiff wire causing a dissection?

A

You introduce it through a catheter (do NOT try to navigate turns or curved vessels with a stiff wire)

32
Q

What does it mean for a J tip wire to be 10 mm?

A

The radius of the curve of the J tip is 10 mm

33
Q

What is the benefit of a J tipped wire?

A
  • Less likely to select side branch vessels that you don’t want (e.g. a 15 mm J tip can help avoid entering the profunda femoris during an anterograde femoral access)
  • Less likely to dig up atherosclerotic plaque
34
Q

What is the size of a catheter whose package is labeled: “4, 110, 0.035”

A

4F (the other numbers are the length and inner lumen diameter)

Note: You can insert this catheter through a 4F sheath and it will accommodate a 0.035 inch wire.

35
Q

What are the two main types of catheters?

A
  • Selective (shaped to perform specific navigational maneuvers)
  • Non-selective (used to inject contrast into medium/large vessels, AKA flush catheter)
36
Q

What are the major non-selective catheters?

A
  • Pigtail catheter (flush catheter with holes along a curled tip to prevent it from moving into smaller branch vessels, better for large vessels like the aorta)
  • Straight catheter (flush catheter with holes along a straight tip, better for medium vessels like the iliac)
37
Q

What are the two major types of selective catheters?

A
  • Side and end hole (can be used with pump injectors because they are less likely to displace/dissect even with rapid bonus injections)
  • End hole only (hand injection only, used for diagnostic angiograms and embolization procedures)

Note: ONLY use end hole only (AKA targeted) catheters for embolization, not side and end hole (AKA non-targeted) catheters.

38
Q

What type of catheter would you choose to access aortic arch vessels?

A

An angled tip selective catheter (best for accessing vessels that are acutely angled away from you):

  • Berenstein
  • Headhunter
39
Q

What type of catheter would you choose to access the renal arteries?

A

A curved selective catheter (best for vessel angles 60-120 degrees):

  • Cobra catheter
  • Renal double curve
40
Q

What type of catheter would you choose to access the SMA, IMA, or Celiac artery?

A

A recurved selective catheter (best for selecting vessels that are obtusely angled toward you):

  • Sos Omni
  • Sidewinder
41
Q

What is a recurved catheter?

A

A catheter whose tip has both a primary curve and a secondary curve (e.g. Sos Omni)

42
Q

What is a co-axial system?

A

When one catheter is placed inside another catheter/sheath

43
Q

What is a guide catheter?

A

A large catheter used to navigate to a distant vessel (a wire can then be placed to exchange the guide catheter for a conventional catheter)

Note: These are also called introducer guides.

44
Q

What type of catheter would you choose when trying to access a very small branch vessel (e.g. super selective)?

A

Micro catheter (2-3F)

Note: You place this through a normal catheter and use a microwire.

45
Q

What is a vascular sheath?

A

A sheath with a hemostatic valve and sidearm (which allows flushing)

46
Q

How much blood are you aiming to displace with contrast during an angiographic run?

A

1/3 to get a good picture

Note: Less if there is a smaller volume of distal arterial bed (e.g. hand arteries can’t tolerate as much blood displacement as more proximal vessels).

47
Q

What is a standard flow rate for large vessels (e.g. thoracic aorta, IVC, pulmonary artery)?

A

20-30 mL/sec (30-40 mL total volume)

48
Q

1 for 4 would be an appropriate flow rate for which vessels?

A

Small vessels (e.g. bronchial arteries, intercostal arteries)

Note: This is 1 cc/second for a total volume of 4 cc.

49
Q

What is the standard flow rate for the abdominal aorta?

A

15-20 cc/sec (for a total volume of 30-40 cc)

50
Q

What is a proper flow rate for the SMA or celiac artery?

A

5-7 mL/sec (for a total volume of 30-40 mL)

51
Q

What is a proper flow rate for medium sized vessels (e.g. carotid, subclavian, femoral, renal arteries) ?

A

4-8 mL/sec (for a total volume of 8-15 mL)

52
Q

What is a proper flow rate for the IMA?

A

4-8 mL/sec (for a total volume of 15-30 mL)

Note: The IMA gets a higher volume than most medium sized vessels (carotid, subclavian, femoral get the same speed but only 8-15 mL).

53
Q

What is a moderate flow rate for angiographic runs?

A

6 cc/sec for 15 mL

Note: This is good for most medium vessels (Celiac and SMA should get higher volume).

54
Q

What determines the maximum flow rate for a catheter?

A
  • Internal diameter
  • Catheter length
  • Number of side holes
55
Q

How can you approximate the maximum flow rate for a catheter?

A

(French size - 2) x 8 cc/sec

Note: Maximum flow for a 3F catheter is about 8 cc/sec.

56
Q

What is the approximate maximum flow rate of a 5F catheter?

A

24 cc/sec

Note: (5-2) x 8 = 24

57
Q

What is the double flush technique?

A

Aspirate a catheter until you get blood in the syringe, then exchange the syringe for a new saline filled syringe (to avoid blood and saline mixing, which can form small clots)

Note: This is mostly used in neurointerventional procedures/cerebral angiograms (even very small clots can cause problems). Most places below the clavicles you can use a single flush technique (same syringe to aspirate and flush) as long as you don’t mix the blood and saline in the syringe.

58
Q

What should you do if you are unable to aspirate a catheter?

A
  1. Try manipulating the catheter (e.g. pulling the catheter back) to see if you were against a side wall
  2. If that doesn’t work, assume there is a clot. Pull the catheter out and clear the clot on the surgical table before reinserting