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4 C. W. Bakal
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diagnostic and interventional procedures to proceed
more rapidly, eliminating the delays for processing cut
films and for repositioning patients. The volume of studies that could be performed in a working day now could
be expanded because the time per study was shortened;
the interventional radiologists could expand their practices and push the envelope. The advent of smaller-profile catheters and hydrophilic guidewires allowed more
expedient selection of smaller arteries for superselective
embolization and infusion. The clinical use of thrombolytic agents began in the late 1980s for acute arterial
and venous occlusions. Renal angioplasty became a first
line technique.
25,26
The introduction of the vascular
stent extended the range of lesions that could undergo
successful angioplasty.
27,28
By 1992, the Health Care Financing Administration
developed a Medicare specialty designation for interventional radiology, and interventional radiology was defined in
Dorland’s Illustrated Medical Dictionar y for the first time.
The Journal of Vascular and Interventional Radiology, born a
few years earlier, was further defining the specialty.
By 1993, stent grafts made their appearance in thetreatment of aneur ysm disease and, to a lesser extent, occlusive disease. The transjugular intrahepatic portosystemic
stent (TIPS), originally conceived in 1969, became a reality for treating the sequelae of portal hypertension.
30
By
1994, the subspecialty was recognized with accredited fellowships and a Certificate of Added Qualifications (CAQ)
granted by the American Board of Radiology, officially
recognizing its distinct status. Inter ventional radiologists
had revolutionized the treatment of hemodialysis patients
by using percutaneous, fluoroscopically guided techniques to enhance the longevity of hemodialysis catheters
and arteriovenous fistulas and grafts.
31–33
Vascular and
interventional radiologists were in the forefront of bringing peripheral vascular disease and abdominal aortic
aneurysm screenings to their communities. Minimally invasive, nonsurgical treatment of symptomatic uterine fibroids by percutaneous embolization allowed the term
interventional radiologist to escape from the medical community to the public’s eye; by the year 2000, direct referral
of patients to interventional radiologists by the Internet
was becoming common.
33,34
New cutting-edge cancer
treatments were being explored. Although magnetic resonance angiography and CTA had supplanted catheterbased diagnostic angiography in many areas of vascular
diagnosis, the specialty grew substantially, predominantly
becoming interventional in nature.
Membership in the SCVIR numbers more than 3,500.
The Cardiovascular and Interventional Radiologic Society of Europe (CIRSE) in Zurich and the establishment
of vascular interventional radiology societies in Central
and Southern Asia and in South America confirms that
interventional radiology is becoming a truly global subspecialty.
REFERENCES
1. Goodman PC. The new light: discovering and introduction; in a
century of radiology. Radiology. Centennial American College of
Radiology and Penn State College of Medicine Website. Available
at: www.x-ray. hmc.psu.edu/rci/centennial.html. Accessed on October 16, 2000.
2. Trevert E. Something about x-rays for everybody: a review. In:
Sprawls P, Petersen JE. The X-Ray Century, vol 2, no. 1. Lynn, MA:
Bubier Publishing, 1896. Atlanta Emory University, Website. Available at: www.cc .emor y.edu/X-RAYS/century.htm. Accessed on October 16,2000.
3. Leriche R. Des oblitérations artérielles hautes (oblitération de la
terminaison de l’aorte) comme cause des insuffisances circulartoires des membres inférieurs. Bull Mem Soc Chir 1923.
4. Seldinger S. Catheter replacement of the needle in percutaneous
arteriography: a new technique. Acta Radiol 1953;139:368.
5. Vorhees AB Jr, Jaretzki A, Blakemore AH. The use of tubes construted from vinyon “N” cloth in bridging arterial defects: a preliminary report. Ann Surg 1952;135:332.
6. Dotter CT, Judkins MP. Transluminal treatment of arteriosclerotic
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obstruction: description of a new technique and a preliminary
report of its application. Circulation 1964;30:654–670.
7. SCVIR News. 1997;10:10–12.
8. Baum S, Nusbaum M, Tumen HJ. Gastrointestinal bleeding. Lancet
1970;1:106–107.
9. Rosch J, Dotter CT, Brown MJ.Selective arterial embolization: a new
method for control of acute gastrointestinal bleeding. Radiology
1972;102:303–306.
10. Baum S, Rosch J, Dotter CT, et al. Selective mesenteric arterial
infusions in the management of massive diverticular hemorrhage.
N Engl J Med 1973;288:1269–1272.
11. Ring EJ, Athanasoulis C, Waltman AC, Margolies MN, Baum S.
Arteriographic management of hemorrhage following pelvic fracture. Radiology 1973;109:65–70.
12. Athanasoulis CA, Baum S, Waltman AC, Ring EJ, Imbembo A,
Vander Salm TJ. Control of acute gastric mucosal hemorrhage:
intra-arterial infusion of posterior pituitary extract. N Engl J Med
1974;290:597–603.
13. Waltman AC, Jang GC, Athanasoulis CA, Ring EJ, Baum S. Emergency gastrointestinal angiography. Geriatrics 1974;29:48–52.
14. Dotter CT, Rosch J, Bilbao MK. Transluminal extraction of catheter
and guide fragments from the heart and great vessels: 29 collected
cases Am J Roentgenol 1971;111:467–472.
15. SCVIR News 1997;10:10.
16. Gruentzig A, Hopff H. Perkutane Rekanalisation chronischer arterieller Veschulusse mit einem nuen Dilatationskatheter. Dtsch Med
Wochenschr 1974;99:2502.
17. Wierny L, Plass R, Porstmann W. Long-term results in 100 consecutive patients treated by transluminal angioplasty. Radiology 1974;
112:543–548.
18. Gerzof SG, Robbins AH, Johnson WC, Birkett DH, Nabseth DC.
Percutaneous catheter drainage of abdominal abscesses: a five-year
experience. N Engl J Med 1981;305:653–657.
19. vanSonnenberg E, Ferrucci JT Jr, Mueller PR, Wittenberg J,
Simeone JF. Percutaneous drainage of abscesses and fluid
collections: technique, results, and applications. Radiology 1982;
142:1–10.
20. Schwarten DE, Cutcliff WB. Arterial occlusive disease below the
knee: treatment with percutaneous transluminal angioplasty performed with low-profile catheters and steerable guide wires. Radiol-
ogy 1988;169:71–74.
21. Brown KT, Schoenberg NY, Moore ED, Saddekni S. Percutaneous
transluminal angioplasty of infrapopliteal vessels: preliminary results and technical considerations. Radiology 1988;169:75–78.
22. Casarella WJ. Percutaneous transluminal angioplasty below the
Vascular and Interventional Radiology: A Brief History
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5
knee: new techniques, excellent results. Radiology 1988;169:271–
272.
23. Bakal CW, Sprayregen S, Scheinbaum K, Cynamon J, Veith FJ.
Percutaneous transluminal angioplasty of the infrapopliteal arteries: results in 53 patients. AJR Am J Roentgenol 1990;154:171–174.
24. Denny DF Jr, Dorfman GS, Cronan JJ, Greenwood LH, Morse SS,
Yoselovitz M. Greenfield filter: percutaneous placement in 50 patients. AJR Am J Roentgenol 1988:150:427–429.
25. Tegtmeyer CJ, Sos TA. Techniques of renal angioplasty. Radiology
1986;161:577–586.
26. Martin LG, Casarella WJ, Gaylord GM. Azotemia caused by renal
artery stenosis: treatment by percutaneous angioplasty. AJR Am J
Roentgenol 1988;150:839–844.
27. Dotter CT, Buschmann RW, McKinney MK, Rosch J. Transluminal
expandable nitinol coil stent grafting: preliminary report. Radiology
1983;147:259–260.
28. Palmaz JC,Laborde JC, Rivera FJ, EncarnacionCE, LutzJD, Moss JG.
Stenting of the iliac arteries with the Palmaz stent: experience from
a multicenter trial. Cardiovasc Intervent Radiol 1992;15:291–297.
29. SCVIR News. 1998;11:11.
30. Rosch J, Hanafee W, Snow H, Barenfus M, Gray R. Transjugular
intrahepatic portacaval shunt: an experimental work. Am J Surg
1971;121:588–592.
31. Mauro MA, Jacques PF. Radiologic placement of long term central
venous catheters: a review. J Vasc Interv Radiol 1993;4:127–137.
32. Valji K, Bookstein JJ, Roberts AC, Ogleview SB, Pittman C, O’Neill
MD. Pulse-spray pharmacomechanical thrombolysis of thrombosed
hemodialysis access grafts: long term experience and comparison
of original and current techniques. AJR Am J Roentgenol 1995;
164:1495–1503.
33. Aruny JE, Lewis CA, Cardella JF, et al. Quality improvement guidelines for percutaneous management of the thrombosed or dysfunctional dialysis access: Standards of Practice Committee of the
SCVIR. J Vasc Interv Radiol 1999;10:491–498.
34. Goodwin SC, Vedantham S, McLucas B, Forno AE, Perrella R.
Preliminary experience with uterine artery embolization for uterine fibroids. J Vasc Interv Radiol 1997;8:517–526.
35. Spies JB, Warren EH, Mathias SD, Walsh SM, Roth AR, Pentecost
MJ. Uterine fibroid embolization: measurement of health-related
quality of life and after therapy. J Vasc Interv Radiol 1999;10(10):
129–303.
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A.R. Abadir and J. E. SilberzweigCathetersand Guidewires
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2
■■■
Catheters and Guidewires
A. RAMSEY ABADIR AND JAMES E. SILBERZWEIG
■ Catheterization Techniques
Interventional radiology uses imaging technology to perform diagnostic and therapeutic procedures at target organs distant from a percutaneous access site. Virtually all
interventional radiology techniques rely on a combination of needle, catheter, and guidewire systems. The basic
principles of interventional radiology are remarkably
similar across procedure types and organ systems. This
chapter addresses the basic instrumentation and techniques used for percutaneous access, using arteriography
as the prototype. Later chapters illustrate how the process
can be adapted to manage a wide range of clinical situations.
The initial method used in diagnostic angiography was
direct needle puncture with contrast injection into the
arterial system. In 1953, Seldinger first described the
combined use of a needle, guidewire, and catheter to
access the arterial system for selective catheter angiography safely and without surgical exposure.
technique for catheter access consists of initial needle
insertion into a blood vessel. Then a guidewire is placed
through the needle and passed into the blood vessel
lumen. The needle is “exchanged,” leaving the guidewire
in place, and finally a catheter is guided over the
guidewire to the desired location. Initially, rubber urinary catheters were used; however, the emergence of
plastics enabled the production of small-diameter, complex-shaped catheters. Seldinger’s technique has remained relatively unchanged since its initial description
for vascular access and has been adapted as a method to
provide percutaneous access to nearly every organ sys-
1
The Seldinger
tem. The venous system, biliary tree, renal collecting
system, peritoneal space, pleural space, and abscess cavities can be accessed using the Seldinger technique.
Vascular access
The basic steps for arterial access usingthe Seldinger technique are as follows: The skin is sterilized with a bactericidal solution, and the patient is draped to allow clean access to the puncture site. Bony landmarks and the
abdomen are checked by use offluoroscopy to ensure that
the planned needle puncture is infrainguinal for femoral
access and that there is no bowel contrast present thatmay
potentially obscure the region to be examined.Local anesthetic is infiltrated, and a small dermatotomy is made with
a no. 11 scalpel. The arter y is palpated both proximally
and distally to the puncture site, lining up the fingers
along the vessel,and the needle is placed parallelto theartery and at an approximately 60-degree angle to the skin.
The tip of the needle is place within the vessel using either
a single- or double-wall technique (to be described later),
at which point, strongly pulsatile blood return should be
observed. If the observed blood return is weak, theneedle
might be only partially within the bloodvessel, directed toward the side wall or a plaque, partially occluded with
thrombus, within a vein, or within a branch arterial vessel;
the needle must be repositioned or removed.
The needle is tipped downward to become more parallel to the vessel, and a guidewire then is placed through
the needle into the lumen, thus securing access. The
guidewire should pass easily into the vessel. Fluoroscopy
is used to confirm guidewire position. If the guidewire
7
8 A. R. Abadir and J. E. Silberzweig
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A
FIGURE 2-1. A: Iliac arteriogram from a left common femoral artery approach demonstrates an intimal dissection (
by a previous right transfemoral catheterization. B: The dissection was “tacked down” by insertion of a Wallstent.
cannot pass easily, one of several circumstances may be
occurring. The needle may be partially embedded in the
vessel wall, the needle tip may be pointing at the side wall
of the vessel, a branch vessel has been punctured, the
vessel is extremely tortuous, or an atherosclerotic plaque
or occlusion may be present. If the needle is partially
buried, subintimal passage of the wire can occur, raising
an intimal flap, which may be flow limiting or even occlusive (Fig. 2-1). If any resistance to wire passage is encountered, the wire should be removed. If pulsatile flow is still
present, another attempt to pass the guidewire may be
made, adjusting the needle to facilitate passage. A contrast injection may help to clarify the position of the
needle tip. If these maneuvers are unsuccessful, the needle should be withdrawn and compression maintained at
the access site for 5 to 10 minutes to avoid hematoma
formation.
The needle is removed over the guidewire while manual pressure is maintained over the puncture site to prevent bleeding and hematoma formation. Clots that may
have formed on the guidewire resulting from the needle
removal should be wiped off using nonfriable gauze such
as Telfa (Kendall Healthcare, Mansfield, MA, U.S.A.). A
catheter now can be passed easily over the guidewire into
the vessel, with tension being maintained on the
guidewire to prevent catheter or guidewire kinking. The
tapered catheter tip must closely approximate the size of
the guidewire so that the catheter tip does not catch on
the vessel wall or kink the guidewire. The catheter can be
advanced to the desired location, using the wire as a
guide. The guidewire can be removed so that saline flush
and contrast may be injected through the catheter. When
the catheter is within the vessel and the guidewire is
removed, heparinized saline must be flushed through the
lumen approximately every 2 to 3 minutes to prevent
formation of a clot within the catheter. Catheter flushing
consists of aspiration of 3 to 5 mL of blood with a
heparinized saline-filled 20-mL syringe, followed by injection of 5 to 10 mL of saline. The syringe tip is angled 45
degrees downward to allow the blood to settle in the
dependent portion of the syringe and to prevent the
introduction of air bubbles or reintroduction of blood.
Double flushing, commonly used during cerebral angiography, consists of the aspiration of blood from one syringe followed by a heparinized saline flush using a second
syringe.
Venous puncture is made in much the same way; however, there are slight differences. Single-wall and doublewall techniques may be used; however, suction must be
applied because venous pressure is usually insufficient to
drive blood through the needle.
Following completion of the procedure, the pulses distal to the catheter insertion site must be assessed before
and after removal of the catheter. Occult emboli or peri-
arrow
B
) caused
catheter thrombosis may have occurred, necessitating
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thrombolysis. The catheter and guidewire need to be
removed from the patient, ensuring minimal vessel
trauma and little bleeding or hematoma formation.
Compression is maintained focally at the arterial puncture site, not the skin entr y site, for 10 to 15 minutes in
patients with a normal coagulation status. Coagulopathic
patients, whether pathologic or iatrogenic, will require
longer compression, as will sites that have had large
catheters placed. The pulse should not be eliminated
during manual compression, but no oozing should be
observed. If no pulse is felt, the vessel may be occluded
by overzealous compression or by compression that is not
being applied over the artery. Devices (e.g., Femostop)
have been designed that mechanically maintain compression once it is set up in the appropriate position. Percutaneous access closure devices have been developed recently and include collagen plugs deposited along the
subcutaneous catheter tract and direct suture of the artery at the access site to aid in the suppression of bleed-
2
ing.
Closure devices may be useful in anticoagulated
patients or following removal of large-diameter catheters.
Access needles
Access needle diameter should be less than the catheter
to be used; otherwise, the hole in the artery will be too
large and blood will leak around the catheter. A 19-gauge
needle is roughly the same size as a 4F catheter (19 gauge
⫽ 1/19 inch). The walls are made of thin steel to allow
passage of guidewires of sufficient size. The proximal end
is called the hub and has handles or a flange for better
control. The tip of the needle may be blunt, with a sharp
inner stylet, or it may be sharply beveled, with no inner
stylet.
The method of access dictates the design of the needle.
Seldinger’s original double-wall technique uses a needle
with a blunt hollow cannula into which a sharp, solid
stylet is placed. Initially, the needle is placed through
both walls of the vessel, and the stylet is removed. The
blunt cannula tip is pulled back slowly until it enters the
lumen and pulsatile blood return is seen. A wire then can
be passed into the vessel (Fig. 2-2).
The one-wall technique employs a sharp, hollow, beveled needle with no inner stylet. The needle is inserted
slowly until pulsatile blood return is seen (indicating an
intraluminal position), and then the wire is passed
through the needle. Only the more superficial wall of the
vessel is crossed.
The choice of technique is primarily one of operator
preference, but there are several technical considerations. The needle puncture in the far wall with the twowall method might create a potential problem with bleeding, although this does not typically occur. The stylet
punctures the wall, spreading the fibers rather than slic-
Catheters and Guidewires 9
FIGURE 2-2. Access needles. Seldinger needle (
right
wall needle (
).
left
). One-
ing them as with the single-wall needle. When the needle
is removed, the elastic arterial wall tends to seal the defect. If thrombolysis is to be performed or the patient is
coagulopathic, however, the one-wall approach may be
preferred. Double-wall punctures in patients with aortobifemoral grafts (which usually are placed anterior to the
native vessels) may enter the deep native vessel first on
withdrawal of the needle, with good blood return seen.
The guidewire, however, will not pass through the diseased native arterial segment. A single-wall puncture is
more likely to enter the graft first, enabling access to
more proximal vessels. Similarly, when placing an inferior
vena cava filter, the occasional femoral artery, which is
immediately anterior to the vein, especially with low
punctures, will be noted on the way in (by the presence
of pulsatile return) before the vessel is accidentally dilated to the size needed to accommodate the filter. Single-wall needles are, by necessity, cutting needles, and
they are helpful in scarred, postoperative groins. Even
with a one-wall puncture, however, the pressure needed
to enter the lumen may cause the vessel to collapse, with
the net result of blood return being seen only after puncturing both walls and withdrawing the needle anyway.
The single-wall needle also is associated with several
pitfalls. Because the needle is hollow, it may become
occluded with tissue. Flushing is therefore recommended
between passes. A more potentially serious problem is a
result of the steep bevel that must be made to enable the
needle to cut the arterial wall. A portion of the needle tip
still may be within the vessel wall while the remainder of
the needle tip is within the vessel lumen. Pulsatile blood
return will be observed, but a wire passed with the needle
in this position can be directed subintimally, thus causing
3
10 A. R. Abadir and J. E. Silberzweig
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FIGURE 2-3. Micropuncture access set. Micropuncture nee-
top
dle, 21-gauge (
bottom
wire (
) coaxial dilators over an 0.018-inch guide-
).
a dissection of the vessel wall. When blood flow is seen,
the needle should be repositioned (slightly withdrawn,
rotated, or occasionally advanced) a millimeter or two to
place the entire bevel within the lumen.
Specialty needles exist for various uses. Translumbar
aortography is performed by using a long, hollow 18- or
19-gauge needle with a Teflon outer sheath. Biliary access
is made with long, fine (21- or 22-gauge) needles. A
Micropuncture access set (Cook, Bloomington, IN,
U.S.A.) is available with a 21-gauge needle and a 0.018inch guidewire (Fig. 2-3). The use of a small needle
minimizes the risk of bleeding in the event multiple
passes are required to obtain vascular access. The needle
and guidewire are coupled with 4Fr or 5Fr coaxial dilators that allow the operator to place a standard 0.035-inch
or 0.038-inch guidewire needed to pass a standard sized
catheter into the lumen.
Sheaths and dilators
If large-diameter catheters are to be used, or if there is
dense scar tissue or a tough synthetic graft is to be
crossed, the use of graduated Teflon dilators may facilitate catheter passage. Dilators are short, stiff, thick-walled
sections of catheter, available in a variety of sizes, with a
long, tapered end that spread tissues more easily than a
diagnostic catheter. Advancing a catheter over a stiffer
wire also may facilitate passage of the catheter into the
vessel and prevent guidewire kinking.
Vascular sheaths are used during cases that require
multiple catheter manipulations and catheter exchanges.
Sheaths should be used during complex manipulations,
such as embolization; if the catheter tip becomes occluded, precluding passage of a guidewire, the catheter
still can be removed via the sheath without losing vascular
access. The use of a sheath decreases the friction on the
catheter at the puncture site, allowing better transmission
of the forces applied, and protects the groin and vessel
from excessive trauma. Sheaths are also useful in patients
with groin scarring from previous surgery, vascular bypass
grafts, and obese patients.
Sheaths are constructed from short segments of thinwalled catheter material, often Teflon, and are sized according to the largest catheter they will accommodate.
For example a 5Fr sheath will accommodate a 5Fr catheter but is actually approximately 6.2 in outer diameter.
They are placed into the vessel at the puncture site and
left for the duration of the case, usually, so that all wires
and catheters pass through them. A hemostasis valve is
attached on the trailing end so that catheters and
guidewires can be exchanged with minimal blood loss. A
flushing sideport is provided and should be connected to
a pressurized continuous saline flush whenever a nonocclusive catheter, guidewire, or nothing at all will be in the
sheath for more than several minutes, as a large volume
of clot may form in the lumen.
Insertion of a sheath is performed with a dilator in its
lumen. If difficulty is encountered, a fluoroscopic check
should be made to ensure the stiff dilator is following the
wire into the vessel. The sheath should also be inspected
to ensure that the thin leading edge has not become
crimped by attempted insertions.
Vascular access sites
Femoral artery access
The femoral approach is generally favored for vascular
work. The large caliber of the femoral vessels allows
placement of relatively large-diameter catheters with a
low risk of vessel thrombosis. The patient is placed in a
supine position throughout the course of the examination. When properly performed, the puncture site can be
effectively compressed against the femoral head following completion of the case.
In arteriography, the goal is to puncture the femoral
artery below the inguinal ligament (which is attached
superiorly to the anterior superior iliac spine and inferiorly to the pubic tubercle) but above the origin of the
profunda femoral artery. Too low a puncture may increase the risk of pseudoaneurysm and arteriovenous
fistula formation.
ligament exposes the patient to an increased risk of
retroperitoneal hemorrhage.
The inguinal crease is not always the appropriate location for a femoral puncture.
the inguinal crease may be located far inferior to the
actual inguinal ligament. Fluoroscopy of the femoral
head should determine the puncture site; however, the
actual inguinal ligament may bow as much as 3-cm inferior to the radiographically determined inguinal liga-
8
ment.
The ligament is usually located 1.5-cm cephalad to
the femoral head. In addition, the mid-femoral head is
virtually always proximal to the bifurcation of the profunda femoral and superficial femoral arteries.
rograde punctures, the skin incision is therefore optimally placed over the lower margin of the femoral head,
with the goal of entering the artery over the medial midfemoral head. Antegrade arterial punctures should aim
similarly but from the opposite direction. If the femoral
4,5
Puncture superior to the inguinal
6
7
Especially in obese patients,
9
For ret-
Catheters and Guidewires 11
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vein is encountered, the needle should be withdrawn
slowly because occasionally the artery overlies the vein. If
the artery has not been crossed, withdrawing the needle
nearly to its tip and redirecting the tip approximately one
centimeter laterally usually will place the needle within
the artery.
Pulseless femoral arteries may indicate aortoiliac occlusion and sometimes may preclude catheterization; however, a pulse might not be encountered in cases of severe
aortoiliac artery stenosis, marked obesity, and hypotension. Techniques used to locate pulseless vessels include
radiographic or anatomic landmarks, fluoroscopic visualization of mural calcifications, sonographic localiza-
10
tion,
the desired vessel for localization.
or contralateral puncture with wire placement in
11
Upper-extremity access
When femoral access cannot be established secondary to
occlusion of the femoral artery, iliac artery or aorta, or
when it is technically advantageous to approach a vessel
from above, an axillary or brachial puncture may be
made. These sites are not routinely used because they are
subject to an increased complication rate. One of the
conditions often cited as a reason for an axillary puncture
is the presence of femoral grafts. Studies comparing
femoral graft puncture with axillary puncture, however,
revealed a greater than fivefold increase in major complications with axillary access.
cently placed grafts, within 6 weeks or so, should be left
undisturbed to avoid graft infection thorough fresh
wounds.
The axillary artery puncture has a higher complication
rate because of the local anatomy, which may result in
both central and peripheral nervous system defects as
well as local vascular lesions. It is more difficult to compress the axillary artery against the humeral head than it
is to compress the femoral artery against the femoral
head. The brachial plexus is immediately adjacent to the
artery and is constrained by fascia. Direct injury to the
brachial plexus may occur with direct needle puncture or
with compression by hematoma formation. Damage to
the femoral nerve during femoral artery puncture also
can occur but happens with about one tenth the frequency.
13
The axillar y artery is smaller than the femoral
artery and is thus more susceptible to thrombosis after
catheterization.
The brachial artery caliber is even smaller, and the
increased risk of thrombosis dictates that it be approached with caution. The brachial artery has a poor
collateral circulation, and brachial artery thrombosis puts
the distal upper extremity at risk. The median nerve
courses with the brachial artery, making it susceptible to
injury. Major complications can be encountered in up to
2.9% of brachial artery catheterizations.
12
Prudence dictates that re-
14
If an axillary or brachial puncture is unavoidable, the
techniques used are the same as for the femoral artery.
No strict radiologic landmarks are used, and careful palpation is important. For axillary punctures, the arm is
abducted 90 degrees or with the hand tucked under the
patient’s head to provide access and stretch the artery.
The puncture is made in the lateral axillary fold as the
artery crosses the humeral head here. High axillary punctures are to be avoided because compression is extremely
difficult without the buttressing effect of the humerus.
The brachial artery is punctured over the mid-humerus
in the bicipital groove or at the antecupital fossa.
The left arm is chosen preferentially. A catheter placed
through the right arm must cross all four of the cerebral
vessel origins to reach the descending aorta, whereas only
the left vertebral artery is encountered if the left arm is
used. In elderly patients who have ectatic, atherosclerotic
aortas, catheters and guidewires may preferentially enter
the ascending aorta and cause unintentional left-sided
heart catheterization. Although cardiac angiography is
interesting, it is best done in a purposeful manner.
Translumbar access
One of the original access techniques used, although not
often used currently, is translumbar aortography. The
technique is used in cases where femoral and axillary
access is unsuitable. The patient is positioned prone, and
a long 18-gauge sheathed needle is advanced directly into
the aorta from a left flank approach. The needle is withdrawn, leaving the sheath in place. After the procedure,
the sheath is withdrawn, and the patient placed on his or
her back with gauze underneath to tamponade external
bleeding. Obviously, no compression can be applied to
the site in this location; therefore, bleeding can be potentially disastrous. The hemorrhage is typically retroperitoneal, often resulting in a hematocrit drop of about
15
3%,
but it can progress and remain unrecognized until
the patient becomes hemodynamically unstable.
presence of coagulopathy is an absolute contraindication
to translumbar aortography. Other potential complications include puncture of an abdominal aortic aneurysm;
injury to the renal, splanchnic, or lumbar arteries; and
even pneumothorax.
Both high and low translumbar punctures have been
described, differing as to whether the aorta is entered
below or above the renal and mesenteric vessels. Many
institutions, if they perform translumbar aortography at
all, use only the high approach to reduce the inadvertent
puncture of an occluded or aneurysmal aorta. Preprocedural computed tomography or ultrasound can be
helpful in this regard.
Some angiographers maintain that the risk of unrecognized hemorrhage precludes the exchange of catheters,
excluding the performance of selective studies, or
16
The
A. R. Abadir and J. E. Silberzweig
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12
repositioning of the catheter once it has been placed.
Several investigators, however, have used exchange and
other techniques to achieve multiple studies from the
translumbar approach.
15,17
■ Guidewires
A guidewire appears deceptively simple. In fact,
guidewires are highly specialized medical equipment
whose properties interact with that of the catheter to
produce a safe and accurate method of catheter placement. The basic characteristics of a guidewire include
length, diameter, tip shape, core stiffness, taper, and coating.
Standard guidewires are 145 cm long, which allows easy
insertion of catheters up to 100 cm long. Exchange
guidewires are typically 260 cm long. The long length
allows for removal of a catheter in its entirety from the
body without dislodging the wire tip, which may be in a
selective position. A new catheter can be placed then into
exactly the same position as the prior catheter.
Except for several highly specialized guidewires, construction of most types of guidewires is similar. A tightly
coiled stainless steel wire provides the body of the
guidewire. The outer diameter of the coil is the width of
the guidewire and usually is expressed in inches (0.018inch, 0.035-inch, 0.038-inch). The standard diameter for
guidewires used in diagnostic arteriography is 0.035
inches. Located centrally within the wire is a fine safety
wire that is soldered to both the proximal and distal ends
of the spring.
18
The safety wire helps prevent uncoiling of
the spring if too much tensile force is applied.
A second thicker, stiffer wire, the mandril core, also is
located within the central canal. The mandril is the prime
determinant of a guidewire’s overall stiffness. Guidewires
range from soft to “coat hanger” stiffness. Almost all
guidewires lead with a distance of nonstiffened spring to
avoid trauma to the vessel walls. However, nearly all
guidewires are stiff as they exit the tip of a catheter or a
needle. The guidewire tip potentially can cause blood
vessel wall injury if it is passed too forcefully.
The mandril core is tapered to allow a graduated transition from the stiff to the floppy sections of the wire.
Both the length of the taper, usually expressed in 5-cm
increments (normal, long taper, long-length taper), and
the lengths of floppy wire are varied to produce wires with
different characteristics. Long floppy segments are useful
for gaining purchase in small tortuous vessels, whereas
stiffer wires allow more controlled catheter manipulation. Movable core wires and variable stiffness wires have
been manufactured to attempt to allow a single wire to
have a variety of characteristics, but these models have
limitations. A variant of the movable core wire is the
steerable or tip-deflecting guidewire. The movable core is
fastened so that, when it is extended through the spring,
the tip of the guidewire is displaced laterally. An example
of how this may be used is to displace the tip of a catheter
through the tricuspid and pulmonic valves in pulmonar y
angiography.
The leading tip can be straight, curved in a “J” configuration or angled. The J tip is often used because it is less
traumatic, leading with a smooth curve rather than a
straight tip, which can catch on atheromatous plaques
and vessel origins. The curve is described by its radius,
usually ranging from 1.5 mm to 15 mm, and chosen to
match the size of the vessel. Large-diameter J-tipped wires
also can be used to keep the wire tip out of branches with
a smaller diameter than the J-shaped tip.
Most standard guidewires are coated with Teflon to
allow easy travel of the catheter over them. Heparinbased coatings also have been used to reduce wire thrombogenicity. More recently, hydrophilic polymer coatings
have been developed that, when wet, have an extremely
low coefficient of friction. A hydrophilic-coated wire can
be passed into small, tortuous vessels more easily and
often is used to cross vessel occlusions. Hydrophiliccoated wires are available with straight and angled tips for
selective catheterization.
Steerable guidewires are also available that can be used
in combination with microcatheters for selective
catheterization of small and tortuous branch vessels. The
angiographer can angle the tips of these guidewires to
facilitate selective catheterization. These guidewires are
generally 0.014 inches to 0.018 inches in diameter.
The choice of guidewire is determined by several factors (Table 2-1). The catheter or needle to be used with
the wire must have an end hole that will accommodate
the guidewire diameter. It is unfortunate to have labored
to place a wire in a difficult vessel and then realize that
the catheter you need to use will not pass over that wire.
The appropriate wire stiffness and taper must be selected.
A floppy wire may be ideal to maneuver into the distal
hepatic artery, but it might become hopelessly coiled in a
tortuous, atherosclerotic iliac artery long before it gets
there. Wires with insufficient stiffness also may not support passage of a catheter into a vessel, even though they
are far out in the vessel. Conversely, a stiff wire passed
through the tip of a shaped catheter just in a vessel origin
is likely to deform the tip and flip it out of the vessel of
interest. A wire with a long taper, however, can allow
sufficient purchase to be obtained by the long floppy
segment so that the stiff portion will follow. Obviously,
this is where experience helps.
■ Catheters
Whether to deliver contrast, inflate a balloon, or pass a
wire-based tool, such as a snare, the catheter is the con-
Catheters and Guidewires 13
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TABLE 2-1. Common Guidewires
Wire Core Stiffness Coatings Tip Features
Newton Medium Teflon J 3–15-mm All-purpose wire for navigating large to medium
Rosen Stiff Teflon J 1.5 mm Useful for visceral artery exchanges where extra
(short support needed, e.g., obese patients, tortuous
taper) vessels, stiff catheters. Typically, 175 cm to 180
Bentson Medium Teflon Straight Very floppy, long straight tip good for crossing
with small, tortuous vessels or stenoses. Unless
floppy tip stiffer portion of wire placed into vessel of
Amplatz Very stiff Teflon Straight May be used cautiously to guide large, stiff
with catheters such as angioplasty balloons, stents, or
relatively IVC filters, and for catheter exchanges. 0.035-in. to
soft tip 0.038 in. diameter
Glidewire Soft to stiff Hydrophilic Straight Extremely slippery wire used to pass occlusions,
(extremely low or angled extremely small or tortuous vessels, or stenoses.
coefficient of Will easily dissect through vessel or other wall,
friction when wet) so use with caution. 0.014-in. to 0.038-in. diameter
“Steerable” Soft to stiff Teflon, Shapeable Used with low-profile “tibial” balloons or coaxial
hydrophilic catheters. 0.010-in. to 0.018-in. diameter, made of
vessels, abscess cavities, etc. J tip is
atraumatic and lumen seeking. Will not traverse
small or tortuous vessels. Typically 0.035-in. to
0.038-in. diameter
cm long, 0.035-in. to 0.038-in. diameter
interest, may not be able to place catheter tip
into selective position. 0.035-in. to 0.038-in.
diameter
steel, platinum, or nitinol
VC, inferior vena cava
duit that allows the interventionalist to access a structure
deep within the body (Table 2-2). Catheters are thus the
most varied of the structures covered in this chapter
because they have been adapted to perform a myriad of
tasks, ranging from portosystemic shunts to draining abscesses. Highly specialized catheters are discussed in subsequent chapters.
In the not so distant past, a catheter was custom made
for each patient. Creating a catheter consisted of selecting
a roll of plastic tubing, cutting it to length, flaring one end
to accept an injection hub, tapering the other end to fit
the guidewire, and finally steaming various cur ves into the
tip to access specific parts of the body.
19
Today preformed
catheters are uniform in construction and available in
almost any configuration. Catheters are constructed from
a variety of materials, including polyethylene, nylon, Teflon, and polyurethane, with some radioopaque material
incorporated in the wall. Polyethylene is easy to shape and
is commonly used. Teflon is slippery and can be used for
passing through scar or graft material. Nylon has good
TABLE 2-2. Common Catheters
Catheter Types Available Features
Straight End hole, flush 3F to 7F Basic catheter used to study vessel punctured or vessels with
Pigtail Flush, 3F to 8F Large internal diameter, high flow capacity
Angled End hole, 3F to 7F
(Berenstein,
Kumpe)
Cobra family End hole, side holes 3F to 7F Visceral catheter: C1 for young patients with narrow aortas, C2 for
Headhunter family End hole 3F to 7F Designed for selective cervicocerebral artery catheterizations
Simmons End hole Requires reformation in the aortic arch or aortic bifurcation
(sidewinder), Sos
Selective,
Mikaelsson
Neff, Omni Flush 4F, 5F Simmons-pigtail hybrid: useful for crossing aortic bifurcation. Neff has
straight takeoffs
patients over 50 yr of age
side holes on leading curve for ease of injecting contralateral
iliac artery. Omni Flush has sideholes on shaft
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