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54 Handling catheters

Diameter

e diameter of the catheter should be as small as

possible to accomplish the task at hand. Most angi-

ography is performed with a 4-Fr or 5-Fr catheter

over 0.035-inch guidewires.

Length

e catheter must be long enough to reach the

target site and still have enough length outside

the patient for appropriate manipulations. Most

commonly used catheters range from 65 cm to

100 cm in length but shorter and longer catheters

are available for specic purposes. In general, the

shortest catheter that will perform the task should

be used (Table 6.1). e catheter length is typically

selected based on the distance from the access site

to the target. Keep in mind, that the length selected

must be supported by the guidewire being used.

Sometimes, a longer guidewire must be placed to

support the chosen catheter.

Head shape

Catheter head shape determines function. A brief

glance at a catheter helps to determine its intended

purpose. e straight ones are generally exchange

catheters. e ones with large rounded heads are

ush catheters, especially if there are multiple side

holes. e angled ones are selective catheters of

some kind, many with specic purposes.

Special features

Special features of catheters include various coat-

ings, radiopaque tips, and graduated measurement

markers.

CATHETER HEAD SHAPE

DETERMINES FUNCTION

e potential for constructing dierent catheter head

shapes is unlimited. Although hundreds are currently

being marketed, most catheter usage in most prac-

tices is based on the consistent and well-developed

use of just a few types. Each specialist has functional

favorites. Flush and selective catheters have divergent

purposes and substantially dierent appearances.

General catheter types are shown in Figure 6.1.

ese include ush, exchange, and selective catheters.

Selective catheters may have either a simple curve or

a complex curve. Some of the catheters commonly

used in endovascular practice are listed in Table 6.2.

Flush arteriographic catheters, such as the pig-

tail or tennis racket, are useful for higher pressure

Table 6.1 Catheter length purposes

Length (cm) Purpose

15–20 Dilator

65 Abdominal aortography with

lower extremity runoff

65–80 Selective renal and visceral

catheterization

90 Arch aortography, thoracic

aortography

100 –120 Selective cerebral catheter

65 –120 Exchange catheter

A B C D

Fig. 6.1 Representative examples of the major

categories of catheters as detailed in Table 6 . 2 .

(A) Flush catheters are used for aortography. They

have an end hole and multiple side holes for high-

pressure, high-volume contrast administration. This

ﬂush catheter example is a tennis racket catheter.

A variation on this is the pigtail catheter, which is

often used for arch aortography. (B) The straight

catheter is used as an exchange catheter, to place

a different guidewire into the artery. (C) Selective

catheters have an end hole and a specially shaped

tip. Selective catheters may have a simple curve, for

directing a guidewire, as with this TegT catheter.

(D) Selective catheters may also have a complex

curve, as in this C2 Cobra. These catheters have

a larger head that must be reformed in the aorta

before being used to cannulate an artery. They

have speciﬁcally designed shapes and are used to

enter aortic side branches such as carotid or renal

arteries. Complex curve catheters are often used to

cannulate the innominate or common carotid arter-

ies in patients with a bovine arch or a tortuous arch.

https://t.me/med1917

Catheter head shape determines function 55

Table 6.2 Catheters for general endovascular practice

Catheter type Catheter name Function Length (cm) Caliber (Fr) Comments

Flush Pigtail Aortography 65, 90, 100 4, 5

Tennis racket Aortography 5

Omni

Flush Aortography: select aortic bifurcation,

select renal artery

65 4, 5

Exchange Straight Exchange guidewires, general

arteriography

70, 90, 100 4, 5

Selective: simple curve

Short bent tip TegT Direct guidewire through lesion or into

branch (30°)

70, 100 5 Other examples: Berenstein,

Vert, DAV

Kumpe More angled than TegT(45°) 40, 65 5

Long bent tip Multipurpose A Direct guidewire, longer tip (45°) 65, 100 5

Multipurpose B More angled than Multipurpose A (70°) 100 5

Hook shape RIM Tight curve 65 5 Other examples: Hook,

ChuangA, B, D, and E,

Shepherd Hook

Selective: complex curve

Cerebral Simmons Reshape to enter difﬁcult arch

branches, direct guide

100 5 Other examples: see Chapter 9,

Table 9.2

Vitek Reshape to enter difﬁcult arch

branches

100, 125 5

Renal C2 Cobra Directs guidewire into side branch at

90-degree angle

65, 80 4, 5 Other examples: SosOmni

C3 Cobra

Renal double curve Directs guidewire laterally and

inferiorly acute angle

80 5 Other examples: renal curve

andrenal curve 2

Abbreviation: RIM, Roche Inferior Mesenteric.

https://t.me/med1917

56 Handling catheters

injection (up to 1200 psi) performed while minimiz-

ing a jet eect that might destabilize arterial plaque

or thrombus. Most aortography and some peripheral

arteriography can be performed with these catheters.

e rounded catheter head can be converted to a

hook shape by positioning a guidewire partially into

the head of the catheter. Most aortography begins

with one of these ush catheters. e shape of the

catheter head may be altered dramatically, depend-

ing on the location of a guidewire placed within it.

Although this is true for all catheters that are not

straight, a catheter with a signicant curve may

assume the widest variety of congurations depend-

ing on the location of the guidewire (Figure6.2). It

is not unusual to have a momentary but irritating

challenge in removing a ush catheter over a guide-

wire. is is because the ush catheter usually has a

head shape that makes the passing guidewire form

a 180-degree loop with the tip of the wire coming

back toward the operator. When the rmer segment

of the guidewire reaches the catheter head, the cath-

eter head ips up straight. If the catheter head is in a

location that is too small in diameter to handle this

maneuver, or there is disease nearby that could be

dislodged by the ipping catheter head, consider

taking another approach. Another option is to pass

the guidewire through the catheter head but leave

the catheter head curved. Go ahead and pull the

catheter back over the guidewire and the curves at

the head of the catheter should straighten. Do not let

go of the guidewire as you walk down the wire when

doing the “pin and pull” maneuver. Sometimes, if

you let go of the wire, the loop in the catheter head

maintains itself and actually pulls the guidewire

back with it.

e straight catheter is useful, as a general

exchange tool, for interval arteriography and to

measure pressure proximal and distal to a lesion.

It can add stiness to a guidewire to allow it to

pass or probe a lesion more easily or uncoil a wire

that has piled up proximal to an unpassable lesion.

When a guidewire is in the correct location but it

is not a sti enough rail over which to pass a larger

endovascular treatment device, an exchange cath-

eter is placed and the indwelling wire exchanged

for an exchange guidewire or a very sti wire.

Selective catheters have either a simple or a com-

plex curved head shape. e dierence between

A B C D E

Fig. 6.2 Catheter head shape depends on guidewire position. The shape of the catheter head can be

signiﬁcantly modiﬁed by the position of the guidewire. This is especially true for ﬂush catheters and com-

plex curve selective catheters. (A) A guidewire is present within the shaft of a hook-shaped visceral cathe-

te r. (B) The hook of the catheter’s head splays out as the guidewire enters the curve. (C)As the ﬂoppy part

of the guidewire tip exits the catheter, the head of the catheter splays further. (D) The catheter straightens

as the ﬁrm portion of the guidewire shaft occupies the curved portion of the catheter head. (E)As the ﬁrm

portion of the guidewire exits the catheter head, the catheter straightens out completely.

https://t.me/med1917

Catheter head shape determines function 57

a simple curve and a complex curve catheter is

demonstrated in Figure 6.3. Every shaped cath-

eter has a primary curve. When a catheter has

only a single curve (primary curve) near its tip, it

is a simple curve catheter. is is usually a “hockey

stick” shape and it provides an angle of trajectory

for a guidewire tip passed through the catheter that

may be anywhere from just a few degrees to almost

90 degrees from the sha of the catheter itself

(Figures 6.3 and 6.4B). A complex curve catheter

has a primary curve and also a secondary curve,

and occasionally a tertiary curve. A complexcurve

Primary curve

Secondary curve

Primary curve

Fig. 6.3 Comparison of simple curve and complex curve catheters. (A) Simple curve catheters have

only a primary curve, which determines how they function. (B) Complex curve catheters have a

primary curve and a secondary curve and, sometimes, “a tertiary curve”. Complex curve catheters

go into the body in the straight conﬁguration because they go in over a guidewire. When a complex

curve catheter is near its destination, the wire is withdrawn and the catheter head begins to take its

shape. The catheter head usually must be reformed or reshaped for the catheter head to take its

functional shape. This is shown in Chapter 9, Figure 9.4.

A B C

E F

Fig. 6.4 Selective catheters in action. (A)ACobra catheter is used for renal artery catheterization.

(B) A Berenstein catheter is used for cannulation of the superﬁcial femoral artery. (C) A tightly curved

hook-shaped catheter is used for catheterization of the visceral arteries. (D)AHeadhunter catheter

can be used to enter the branches of the aortic arch. (E) A Simmons catheter is used to cannulate the

carotid and innominate arteries. (F)AShepherd Hook catheter is used to cross the aortic bifurcation.

https://t.me/med1917

58 Handling catheters

catheterheadneeds to bereshaped inside the arte-

rial system before it can be used to selectively can-

nulate a side branch (Figures 6.3 and 6.4E). e

complex curve catheter head assumes a relatively

straight conguration while it is being passed

over the guidewire. When it arrives at its destina-

tion, the guidewire is withdrawn and the complex

curve catheter attempts to shape itself. Specic

maneuvers must be performed to achieve the cor-

rect shape. is is discussed in detail in Chapter9.

e larger the head of a complex curve catheter,

the more space in the vascular system is needed to

reshape the head. e largest of the complex curve

catheter head shapes is the Simmons 3.

e bent tip Berenstein catheter is a simple

curve selective catheter, but it can be used simul-

taneously for general applications. is catheter is

useful for directing a guidewire through a critical

lesion or into a branch vessel. e bend at the tip

of the catheter confers directionality to the guide-

wire tip. e angled Glidecath

is similar but with

a soer catheter tip. e soness of the tip slightly

blunts the degree of angulation as the wire leaves

the catheter head. e vertebral catheter (Vert)

provides slightly more angulation and the catheter

tip is a little bit stier. Hook-shaped catheter heads

are useful for turning an acute angle at a tight cor-

ner. Complex curve catheter heads have a curve

in one direction, then back in the other direction.

ese are used primarily to select out aortic side

branches for cannulation. Examples include the

Simmons and the H3 Headhunter cerebral cath-

eters. Many head shape congurations have been

designed for selective catheterization, each with a

dierent purpose (see Chapter 9 for a detailed dis-

cussion of selective catheterization).

e rate at which contrast may be administered

through a catheter varies with the catheter caliber,

its length, and the number of side holes (Table 6.3).

DESCRIBING CATHETER BEHAVIOR

●

Trackability. e ability of the catheter to fol-

low the guidewire through tortuous vessels and

around corners without pulling the wire out

of its intended location or without halting its

advance over the wire.

●

Pushability. e description of how a force

applied by the operator at the hub of the cath-

eter relates to the forward movement of the tip

(the leading edge) of the catheter.

●

Crossability. e facility with which a cath-

eter follows the guidewire across a lesion or

through a diseased arterial segment.

●

Steerability. e steering responsiveness of the

catheter tip to handling maneuvers performed

at the hub.

●

French. e scale used to size catheters

(1 Fr = 0.33 mm).

HANDLING CATHETERS

Aer the guidewire has been placed into the major

ow stream of the arterial segment of interest, the

next challenge is to pass the catheter into the cor-

rect location. e catheter should be suitable for

the diameter sizing of the guidewire. In general,

the catheter will follow the guidewire when it is

advanced incrementally and the wire is pinned to

ensure that it does not also advance. Do not advance

the catheter unless the guidewire is pinned. If work-

ing over a hydrophilic guidewire, the wire must be

pinned with a pincer grasp so that it is not acciden-

tally advanced with the push forward on the cath-

eter. e hydrophilic guidewire must also be wet

to have pushability of the catheter. e catheter is

advanced by grasping it a certain distance from the

hub of the sheath, usually with the dominant hand,

and giving it a push. Do not advance the catheter

by grasping on the catheter hub. Grasp the catheter

along its sha and at a distance from the hub of the

sheath that can be supported by the overall stiness

of the combined guidewire and catheter. If the n-

gers are too far from the place where the catheter

goes into the sheath, the catheter and guidewire

will just bend, instead of the catheter sliding over

Table 6.3 Contrast media ﬂow rates through

ﬂush and selective catheters

Type

Caliber

(Fr)

Length

(cm)

Maximum

ﬂowrate

(mL/second)

Flush

(multiple

side holes)

4 65 19

4 100 15

5 65 32

5 100 27

Selective

(end hole)

5 65 15

5 100 11

Data from Cook Medical, using 100% Oxilan 350

at25°C.

Maximum pressure = 1200 psi.

https://t.me/med1917

Handling catheters 59

the wire. Each catheter and guidewire combination

has a certain body to it based on the overall stiness

and strength of the combined structures. e stier

the guidewire–catheter combination, the farther

down the catheter may be grasped with each incre-

mental grab and push by the operator. An innate

sense will be developed for this aer undertaking

many cases. If the catheter is grasped too far down

the sha, it will bend instead of advance. If it is

grasped in increments that are too small, this easy

part of the case may take all day.

e catheter will not advance easily over the

oppy tip portion of the guidewire (Figure 6.5).

When the catheter reaches the oppy portion of

the wire, the catheter head begins to take its shape

and pushability is dramatically decreased. e

guidewire may be advanced to ensure that a rm

segment of the wire is available for the catheter to

advance.

If the intended catheter cannot be advanced

over the guidewire and pushability is lost, con-

sider a stier wire to give additional support to

the catheter. is situation is oen encountered

in tortuous arteries, especially if they are calci-

ed. If the catheter cannot be advanced over the

guidewire through a lesion, the lesion itself may be

providing the resistance; either the stenosis is so

severe that the guidewire itself occludes the resid-

ual lumen, or the wire is subintimal.

When the catheter cannot be advanced into

position because of signicant vessel tortuos-

ity or because of the long distance between the

catheter head and the entry site, a steady and

gentle withdrawal of the guidewire while the

catheter is advanced decreases friction at the level

of the catheter head and usually accomplishes

the requisite advancement if the distance is not

too far. is is called the “push-pull” technique.

e risk of using this maneuver is potentially los-

ing guidewire access. Do not advance the cath-

eter beyond the end of the guidewire or allow

the catheter head to reform during advancement.

If the guidewire–catheter combination tends to

buckle freely, the operator can choose to insert a

stier wire. Another option is to leave the guide-

wire in place, remove the catheter, insert a long

sheath to decrease friction, and reinsert the cath-

eter through the sheath.

Technique: Catheter handling

1. Prepare the catheter by ushing and wiping

with heparin–saline solution.

2. Choose a catheter size, length, and head shape

that will most easily accomplish the proposed

task.

3. Place the guidewire in the correct location.

is is probably the most important factor in

successful catheter placement.

4. Whenever a guidewire is in place across the

access site without a catheter, hold pressure

at the arterial entry site until the appropri-

ate dilator, sheath, or catheter is passed to

tamponade bleeding from the arteriotomy.

A B C D

Fig. 6.5 Advancing the catheter over the stiff portion of the guidewire. (A) The catheter is advanced

into the arterial entry site over the ﬂoppy portion of the guidewire, which lacks the shaft strength to

support advancement of the wire. (B) The catheter buckles and advancement stalls. (C) The guidewire

is advanced so that the ﬂoppy portion is well inside the vasculature. (D) The catheter is advanced over

the stiffer portion of the guidewire.

https://t.me/med1917

60 Handling catheters

Bleeding into the subcutaneous tissue during

exchanges leads to postprocedure ecchymosis.

Pressure in the right place helps to minimize

the likelihood of hematoma formation.

5. Use a mosquito clamp to dilate the skin entry

site to the appropriate size for the intended

sheath or catheter.

6. Pass the sheath or catheter through the

skin and so tissue over the sti portion of

the guidewire, not on the oppy segment

(Figure6.5).

7. Consider using sequential arterial dilators, a

stier guidewire, or a hemostatic access sheath

if the catheter cannot be advanced across the

entry site.

8. Advance the catheter incrementally, a few

centimeters at a time.

9. Handle the catheter near its entry site when

advancing and at its hub when steering.

10. Maintain hand control of the guidewire.

Anassistant should pin the guidewire so that

it does not simultaneously advance.

11. If the catheter will not cross a lesion and

arteriography is the goal, use a dierent

approach and do not force it. If therapy is

the goal (e.g.,balloon angioplasty or stent

placement), make sure the guidewire is in

the correct location across the lesion. en

predilate the lesion with a small diameter

angioplasty balloon.

12. If the catheter will not advance because of

long distance and/or multiple turns from

the leading edge to the operator’s hand, and

there is plenty of guidewire in place ahead

of the catheter tip, gently and steadily with-

draw the wire while advancing the catheter

to reduce friction. Continuous fluoros-

copy is required during this maneuver to

ensurethat the guidewire is not withdrawn

too far.

13. If the catheter has a longer distance to travel

and cannot be advanced, it is usually due to

accumulated friction. Place a long sheath to

decrease friction, use a stier guidewire, or

choose an alternative entry site.

14. Aer the catheter is in place, aspirate and

ush with heparin–saline solution. Do not

inject anything unless there is appropriate

blood return.

15. Pu contrast to verify placement and ensure

that the catheter tip is in a safe position before

high-pressure injection is performed.

16. When removing or exchanging the catheter,

maintain guidewire placement by “ walking

along” the wire while the catheter is

being pulled (Figure 6.6). Intermittent

fluoroscopy checks should be performed

to ensure that the guidewire position is

maintained.

17. If the end of the catheter becomes knotted,

pass a sti guidewire into the catheter to

untangle it.

18. If there is any doubt about the location of

the catheter, make sure it is intraluminal.

Check for blood return. Twirl the catheter

and visualize the catheter head moving using

Fig. 6.6 “Walking along” the guidewire to

remove a catheter. When a catheter is exchanged,

the guidewire position is maintained while the

catheter is removed. The usual way to do this is

to use two hands and the “pin and pull” tech-

nique. The guidewire is pinned with one hand

and the catheter pulled with the other hand.

The alternative is to use one hand to remove

the catheter. (A)The catheter hub is grasped

between the thumb and the foreﬁnger and the

guidewire is grasped between the fourth and ﬁfth

ﬁngers of the same hand. (B) The catheter hub

is withdrawn while the guidewire position is held

constant. Thefourth and ﬁfth ﬁngers then grasp

the guidewire again at a further distance along its

length and the maneuver is repeated. This creates

the appearance of the hand “walking along” the

guidewire.

https://t.me/med1917

Handling catheters 61

uoroscopy to be certain that it moves freely.

Pu contrast to see if it rapidly enters the ow

stream rather than staining the wall of the

artery or remaining stagnant.

19. It is common to have diculty identifying

the catheter as it is being placed. Consider

using a catheter with a radiopaque tip. When

advancing any catheter over a guidewire, there

is a slight bend of the wire at the location of

the catheter head and this imprint can be

monitored uoroscopically as it is advanced.

20. Remove the catheter over a guidewire to

straighten the catheter head. is prevents

injury to the endoluminal surface.

https://t.me/med1917

Guidewire and catheter passage

THE GOAL OF THE PROCEDURE

DETERMINES THE COURSE OF

THE GUIDEWIRE–CATHETER

APPARATUS

e guidewire–catheter combination is the endo-

vascular workhorse. Before you go to any trouble,

be as precise as possible about establishing the goal

of the procedure and anticipating the likely scope of

the arteriography or intervention. e operator must

decide what guidewire–catheter combination should

be used in any given case and decide how to get the

selected combination into the position required.

Aer percutaneous access has been achieved (see

Chapter 2), an initial sheath is placed (see Chapter 3).

Guidewires and catheters have become familiar tools

(see Chapters 4–6), and the next step is guidewire

and catheter passage to the desired location. e goal

of the intended procedure should be well proscribed

prior to the puncture. Whether arteriography or a

therapeutic intervention is planned will inuence

the puncture site choice and the approach. Options

should be considered for converting the procedure

from a strategic one to a therapeutic one if the need

should arise. Access for endovascular therapy is dis-

cussed in Chapter 14.

When arteriography is the goal, the small-

est acceptable access sheath should be placed.

Angiographic catheter head placement at specic

locations is required for visualization of the desired

anatomic area. Selective catheterization for arteri-

ography or therapy requires specic steps, which are

discussed in Chapter 9. Details of catheter head place-

ment for arteriography are discussed in Chapter 10.

ese maneuvers have been separated into a stepwise

approach for illustrative purposes. As the operator

gains facility, one step leads to the next in a ow of

events that lead toward the goal of the procedure.

Initial catheter placement

Bony landmarks or other anatomic signs are usu-

ally adequate to establish the correct location for

catheter head placement (Fig u re 7.1). e catheter

head may be advanced or withdrawn slightly with-

out reintroducing the guidewire, since the ush

catheter tip is usually rounded. Hand-powered

injection of contrast to establish the position is

usually worthless through a 5-Fr catheter into the

aorta. Hand-powered contrast injection may be

used to visualize smaller, lower-ow arteries. Aer

the catheter is in place, aspirate, remove bubbles,

ush with heparin–saline, and connect to the

injector, uid meniscus to uid meniscus. en

have the technician aspirate through the injector

and inspect the line for air bubbles.

Fluoroscopy for catheter placement

Table 7.1 summarizes some general concepts about

when to use uoroscopy for guidewire and catheter

placement. e guidewire should be advanced so

that its oppy portion extends beyond the loca-

tion desired for catheter head placement. Aer

the guidewire is appropriately placed, uoroscopy

stops while the catheter is prepared and advanced

over the guidewire outside the patient. Fluoroscopy

is initiated again when the catheter is in the artery.

e progress of the catheter is monitored using

uoroscopy until it is in the desired location. Some

catheters have a bright tip or radiopaque tip to help

visualize them as they are being placed. If not, the

catheter is typically visualized as an enhanced

shadow advancing over the wire as the added prole

of the wire and the catheter is apparent in compari-

son to the shadow of the wire alone. Fluoroscopy is

used as the guidewire is withdrawn to ensure that

https://t.me/med1917

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10.10.20267 Мб0Книга_3929_Библиотеки_им_академика_М_И_Перельмана.pdf