Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3955_Библиотеки_им_академика_М_И_Перельмана.pdf
Venous Access 49
Fig. 4 Diagram illustrating
the variations in the RIJV
anatomy. The RIJV lies
antero-lateral to the right
common carotid artery in
71% of cases, lateral in 9%,
and anterior in 20% of cases.
Anatomical variation reduces
the success rate of the
landmark method of venous
puncture
Performing the Procedure
Using Anatomical Landmarks
Historically, internal jugular access was performed using the landmark method,
based on a knowledge of the surface anatomy.
• The carotid artery is palpated and the needle is inserted lateral to the artery at the
apex of the triangle formed by the two heads of sternocleidomastoid muscle.
• The needle is aimed laterally, pointing toward the ipsilateral nipple aspirating as
the needle is advanced.
Using Ultrasound Guidance
For interventional radiologists, with access to ultrasound, there is no reason to
perform IJV access without ultrasound guidance (Figs. 5, 6 and 7).
• The transverse image of the vein is probably preferable to the longitudinal image.
• The vein is usually catheterized in the mid-to-lower neck.
• If available a micropuncture system should be used in all cases. This limits the
possibility of severe hemorrhage if the carotid artery is punctured inadvertently.
• Efforts should be made to reduce the possibility of air embolism by using a tilt-
ing table and performing catheter exchanges though non-valved sheaths (e.g.,
peelaway sheaths) with respiration suspended.
50 C.L. Bent and M. Matson
Fig. 5 Longitudinal
ultrasound image of the RIJV.
This orientation allows
complete visualization during
needle puncture and is
preferable for deep venous
punctures
Fig. 6 Ultrasound-guided
RIJV puncture. Notice the
transverse orientation of the
linear 7.5 MHz ultrasound
probe. A vascular access
needle is used attached to a
saline syringe at a 45
◦
angle
Venous Access 51
Fig. 7 Transverse ultrasound image of a RIJV needle puncture. As the needle tip (echogenic focus
arrowed) enters the RIJV, there is distortion of the anterior vessel wall. Aspiration via the syringe
confirms intravascular position
Complications
• Carotid artery puncture and cannulation: an uncommon complication if the
operator is experienced in ultrasound-guided venipuncture.
• Pneumothorax (0–2.5%) or hemothorax: this is minimized by ultrasound-guided
puncture.
• Air embolism (0.3%): avoid by using a tilting table and place the patient with the
head down. Suspend respiration during catheter exchanges if using a peelaway
sheath.
• Arrhythmias: avoid passing the guidewire into the right ventricle. Preferable
guidewire placement is within the IVC.
• Infection.
Access into the Subclavian Vein
• The subclavian vein is commonly used for central venous catheterization.
• However, it is a poor first choice for venous access, because even with ultrasound
guidance, the risk of pneumothorax or hemothorax remains higher than for access
via the IJV. Moreover, the risk of long-term stenosis and thrombosis is increased
compared with the internal jugular approach, which is particularly relevant in
patients with renal failure who require patent subclavian veins for hemodialysis
fistula function.
• On a practical level, the left subclavian vein is the preferred side versus the right,
due to the longer, straighter course via the left brachiocephalic vein into the right
atrium. In contrast, there is a sharp angulation at the junction between the right
subclavian vein and the right brachiocephalic vein, which may promote catheter
kinking during central venous line insertion.
52 C.L. Bent and M. Matson
Indications
• The most frequent indication for subclavian vein access is the insertion of a tun-
neled central venous catheter (e.g., for dialysis or total parenteral nutrition) when
the internal jugular vein route is no longer available.
Contraindications
• Subclavian vein thrombosis
• Local skin sepsis
Patient Preparation
• Similar to IJV puncture, the patient should be supine, in a Trendelenberg posi-
tion of 15
◦
, with the head turned 45
◦
to the contralateral side to enable adequate
exposure of the neck.
• A towel placed between the shoulder blades encourages the clavicles to move
posteriorly allowing easier access to the subclavian vein.
• Full antiseptic preparation.
Anatomy
• The subclavian vein begins as a continuation of the axillary vein at the lateral bor-
der of the first rib. Here it grooves the first rib immediately anterior and inferior
to the scalene tubercle, the insertion site of the scalene anterior, which separates
the vein from the subclavian artery.
• The subclavian vein continues behind the medial third of the clavicle where it is
immobilized by small attachments to the rib and clavicle.
• At the medial border of the anterior scalene muscle and behind the sternoclav-
icular joint, the subclavian vein unites with the internal jugular vein to form the
brachiocephalic vein.
Performing the Procedure
Using Anatomical Landmarks
• A single-part needle is inserted into the skin two-thirds of the way along the
clavicle and 1 cm inferior to its inferior margin.
• The needle is passed deep into the clavicle, aiming toward the head of the clavicle.
Venous Access 53
Using Ultrasound Guidance
• Subclavian vein access should be performed using ultrasound guidance.
• During ultrasound-guided subclavian vein puncture, the site of needle puncture
is determined by the portion of subclavian vein, which is most visible.
• A micropuncture system i s sensible and limits hemorrhage and the risk of
pneumothorax.
Using Fluoroscopic Guidance
• If the subclavian vein is poorly visible by sonography (this is very unusual if the
vein is patent), the vein can be punctured using fluoroscopic guidance.
• A venogram is performed from a peripheral vessel. The subclavian vein may be
punctured using either the venographic image and/or a road map.
Complications
• Pneumothorax: this is avoided by using ultrasound guidance for catheterization.
• Hemothorax or local hematoma due to puncture of the subclavian artery: this is
avoided by ultrasound guidance.
• Inadvertent access into the subclavian artery: this is avoided by ensuring that all
catheter manipulations are performed under fluoroscopic guidance. Ensure that
catheters and guidewires follow the appropriate course though the central veins
(and not through the arteries!).
• Pseudoaneurysm of the subclavian artery.
• Arteriovenous fistula.
• Air embolism: this is avoided by using tilting tables and suspending respiration
if exchanging catheters through peelaway sheaths.
• Arrhythmias: avoid passing the guidewire into the right ventricle.
• Catheter compression between the clavicle and first rib: an unavoidable compli-
cation of this access route.
• Phrenic nerve palsy.
• Infection: reported cases of infection are generally lower than for that with
internal jugular vein catheters.
Access into the Inferior Vena Cava (IVC)
• Translumbar inferior vena caval access may be used as an access port in patients
who require long-term hemodialysis or who require chemotherapy, but have
exhausted traditional access sites.
• It is not a common access route because of complications and poor long-term
durability.
• It is generally used as an access route of last resort.
54 C.L. Bent and M. Matson
Contraindications
• IVC thrombosis
• Local sepsis
Patient Preparation
• The patient is placed prone on the angiography table.
• Full antiseptic preparation.
• If the procedure is going to be performed under fluoroscopic guidance, it is help-
ful to place a transfemoral guidewire into the IVC, which may act as a target for
percutaneous puncture of the IVC.
Anatomy
• The IVC is a retroperitoneal structure and is located on the right side of the ante-
rior margin of the lumbar spine. The renal veins drain into the IVC at the level of
L1 or L2 vertebral bodies.
Performing the Procedure
• The procedure may be performed using fluoroscopic or CT guidance.
• Fluoroscopic guidance is probably preferable for most straightforward proce-
dures, and is facilitated by the use of a target such as a transfemoral guidewire or
a wire loop snare.
• A puncture site is chosen just cephalic to the right iliac crest and approximately
8–10 cm to the right of the midline.
• Under fluoroscopic guidance, a 21G 15 cm long needle is advanced cephalad and
medial to the anterolateral margin of the vertebral bodies aiming to puncture the
IVC at the level of L2/L3 below the renal veins.
• A small caliber access s ystem such as an Accustick system (Boston Scientific
Corp, Galway, Ireland) is ideal for this procedure.
• A 0.018-inch wire is inserted through the needle, and the needle is exchanged for
a three part dilator enabling the insertion of a 0.035-inch very stiff guidewire.
• A 4 or 5F catheter is inserted into the IVC, and contrast medium is injected to
confirm entry into the IVC and not the renal vein.
• The track is subsequently dilated to the necessary diameter for the catheter
required.
• It should be emphasized that the track is usually quite long and care should be
taken during track dilation not to lose access or to buckle the guidewire.
Venous Access 55
Complications
• Air embolism: care during venous access is vital to prevent air entry into the IVC.
Perform catheter exchanges using a peelaway sheath in suspended respiration.
• Right ureteric damage: ensure that the needle is in close proximity to the vertebral
bodies to avoid this complication.
• Catheter migration or dislodgment into the subcutaneous tissues or retroperi-
toneum:
b
A late rather than an acute complication.
b
This is one of the major drawbacks of this access route.
b
Maintaining the position of the catheter tip in the IVC, despite the constant
motion of the body, is a real and often insurmountable challenge.
• Venous thrombosis (IVC or renal vein): in view of the high flow within the IVC
and its large caliber, thrombosis of the IVC is less common than other routes of
access.
• Infection.
Key Points
• Apart from cannulation of superficial veins in the extremities, ultrasound
guidance should be used for most procedures to minimize complications.
• Full antiseptic preparation should be performed in all cases.
• Familiarity with standard interventional radiology skills is essential for
complicated venous access routes.
General Principles of Angioplasty and Stenting
Elias N. Brountzos and Efthymia Alexopoulou
Pathophysiology of Angioplasty
• Percutaneous transluminal angioplasty (PTA) involves the dilatation of a vascular
stenosis or occlusion with a balloon catheter.
• The mode of action of PTA is fracture of the arterial plaque and a localized tear
or dissection of the arterial wall. The tear may extend circumferentially or longi-
tudinally in the vessel wall and may extend into the internal elastic lamina or into
the media. The adventitial layer remains intact. This mechanism accounts for the
majority of luminal increase (>70%).
• Balloon dilatation also causes stretching of the medial layer if the balloon
diameter is adequately oversized.
• Microscopic plaque material may become separated and embolize distally.
However, this is usually asymptomatic in the peripheral circulation. In
carotid artery angioplasty, this phenomenon has potentially more severe
consequences.
• Concentric arterial lesions respond well to PTA, because the arterial plaque and
the arterial wall layers are dissected in a uniform fashion, which improves the
increase in the luminal diameter (Fig. 1 A and B).
• Eccentric arterial lesions may respond less well to balloon dilatation. This is
because the wall opposite the plaque is stretched by the balloon rather than the
plaque itself (Fig. 1C and D). Once the balloon is deflated, the normal elastic wall
may recoil, resulting in an unsatisfactory result.
• Vascular stents provide an internal scaffold for the vessel lumen (Fig. 1 E). The
advantages of stents include
b
Rapid, reliable, and sustained increase in the luminal diameter
b
Entrapment of vulnerable plaque material that may cause embolization
b
Elimination of elastic recoil
• A cutting balloon consists of a non-compliant balloon with microblades (athero-
tomes) mounted longitudinally on its outer surface. The blades are designed
to score a lesion during balloon inflation, allowing easier angioplasty at lower
pressures. Cutting balloons are used most frequently in hemodialysis patients
with graft or fistula-related venous stenoses resistant to standard angioplasty.
57
R.A. Morgan, E. Walser (eds.), Handbook of Angioplasty and Stenting Procedures,
Techniques in Interventional Radiology, DOI 10.1007/978-1-84800-399-6_6,
C
Springer-Verlag London Limited 2010
58 E.N. Brountzos and E. Alexopoulou
Fig. 1 The mechanism of action of balloon angioplasty in atherosclerotic lesions: (A) The bal-
loon catheter is centered in a concentric arterial lesion. (B) Balloon dilatation results in uniformly
controlled wall dissection with adequate luminal gain. (C) The balloon catheter lies within an
eccentric arterial lesion. (D) After balloon dilatation the wall opposite to the plaque is stretched.
(E) The stent provides an internal scaffold for the arterial lumen with excellent luminal gain
General Principles of Angioplasty and Stenting 59
They may also be used to treat recurrent in-stent stenosis, and peripheral graft
anastomotic stenoses if standard PTA is unsuccessful. It is usually necessary to
use a conventional balloon after a cutting balloon has been used to achieve the
optimal result.
Pre-interventional Work-Up
• A detailed clinical history should be obtained. Information regarding vascular
symptoms, relevant comorbidity, (including cardiac disease, renal impairment,
diabetes), risk factors for vascular disease, i.e., smoking, hyperlipidemia, and a
history of contrast allergy s hould be ascertained.
• Perform a detailed physical examination. Focus on findings pertinent to vascular
disease (palpate pulses, skin temperature, skin lesions, etc).
• Ask about current medication. You may need to stop, change, or modify some
medications, e.g., warfarin, i nsulin, clopidogrel.
• Review all recent vascular imaging studies to decide the optimal site and direc-
tion of arterial puncture, i.e., right versus left femoral artery, antegrade versus
retrograde puncture.
• Evaluate the morphology of the lesion to select the optimal treatment, i.e., PTA
versus stent. As a rule, short stenoses are more likely to respond favorably to PTA,
while PTA of long occlusions is associated with lower immediate and long-term
success rates. Consider whether a stent would be the better primary treatment
instead of PTA.
• If renal insufficiency is present, intravenous hydration should be started the day
before the procedure. Consider the use of iso-osmolar contrast agents.
• Consent the patient regarding the alternative treatment modalities, the success
and failure rates, and the potential complications.
The Procedure
• The patient is positioned on the angiographic table and draped in a sterile fashion.
• ECG and blood pressure monitoring is commenced before the procedure and is
maintained until the patient leaves the interventional suite.
• In some clinical settings, for example in carotid artery stenting, antiplatelet
medications such as clopidogrel 75 mg daily, and acetylsalicylic acid 160 mg
daily are administered 3–7 days before the procedure, to minimize thrombotic
complications and the development of restenosis.