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122 L. Ratnam and R. Morgan
Fig. 12.1 Angiogram of renal
metastasis in the femur. The
metastasis (white
arrowheads) is highly
vascular and early draining
veins (black arrows) are seen
indicating AV
shunting
• Collateral blood supply: in the presence of tumor, neovascularization may be
present (Fig. 12.1). In atherosclerotic patients, collateralization may be present
as a result of arterial stenosis.
• Arteriovenous shunting (AV): in the presence of AV shunting (Fig. 12.1), the
embolic material must be carefully chosen to avoid passage through the shunt,
causing non-target embolization (e.g., stroke during embolization of pulmonary
AV M ) .
During the Procedure
• Choice of embolic agent: this must be tailored to the clinical indication and
anatomical site. Frequently, a final determination of the size of the embolic
agent cannot be made until the final catheter position has been achieved and an
angiogram showing the arterial territory supplying the lesion has been obtained.
• Catheters
◦ Choice of catheters
◦ Size: if you plan to use a co-axial catheter, then make sure that its diameter and
length are compatible!
◦ Lumen: make sure that the embolic agent will pass through the catheter.
◦ Type: end-hole-only catheters are essential. Coils may partially extrude
through a sidehole and block the catheter (Fig. 12.2). Particles and liquids will
come out through the sideholes.
12 Complications of Embolotherapy 123
Fig. 12.2 Attempted coil
deployment through a
sidehole catheter (black
arrow). The coil has partly
extruded through the sidehole
(white arrowhead) blocking
the catheter. The catheter and
coil are being removed
through the femoral sheath
• Catheter position: ensure a stable catheter position before commencing
embolization. Catheters can have a tendency to “jump back” if the position is
not stable, which may result in non-target embolization.
• Avoid: sharp angles and redundant loops of catheter. These predispose t o loss
of position as coils are introduced.
• Test stability: check that insertion of the coil pusher wire does not displace the
catheter. Only deliver coils with a flush technique, if the catheter remains in
place during a forceful test injection of saline.
• Maintain and check the catheter position during embolization.
• Prevention of reflux: this is a common cause of non-target embolization.
• Use good quality fluoroscopy when injecting liquid and particulate agents.
Look for flow toward the target. Slow or stop injection as flow slows.
• When flow slows, flush the catheter with saline under fluoroscopic control to
ensure that no embolic material remains in the catheter.
• If flow has stopped DO NOT FLUSH! Either aspirate the catheter until free-
flowing blood is obtained or remove the catheter and flush outside the patient.
• Consider occlusion balloons to prevent reflux when embolizing with liquid
agents.
• Go with the flow: if possible, try to embolize in the direction of blood flow:
In principle, it is safer to embolize in free-flowing blood as flow will carry the
embolic agent forward to the target.
124 L. Ratnam and R. Morgan
• Imaging:
• Consider use of road maps during embolization: subtraction techniques are
very sensitive to contrast and help visualization of the embolic agent relative
to normal anatomy.
• Stopping:
• Embolize to a pre-determined endpoint.
• Avoid over-embolization (“the enemy of good is better”).
• Resist the temptation to insert one more coil if the endpoint has been achieved.
This last coil is frequently the one that migrates!
Detection and Recognition
During the Procedure
• Tactile cues: use caution when there is resistance to passage of coils or injec-
tion of particles or liquid. Consider that the delivery catheter may be blocking or
kinked.
• Visual cues: use contrast and fluoroscopy especially when approaching the end-
point. Reduce the rate of embolization if flow is slowing or if there is intermittent
reflux outside the vessel to be embolized. Coil/glue migration can be visualized
with fluoroscopy.
Post-procedure
Clinical Assessment
• Non-target embolization: always assess and document the presence or absence
of peripheral pulses at the beginning of arterial embolization procedures.
Neurological status should be documented in neuroembolization procedures,
and in cases where catheters or guidwires have been manipulated within the
aortic arch.
• Post-embolization syndrome (see Chapter 13): this is usually benign and self-
limiting. When it is not self-limiting, consider the possibility of sepsis and/or
abscess formation.
Blood Tests
• White cell count and CRP to monitor for infection
• Blood cultures
• Urea and electrolytes
12 Complications of Embolotherapy 125
Imaging
• Plain films will demonstrate embolized coils (Fig. 12.3).
• Computed tomography (CT) or ultrasound for assessment of abscess formation.
• Magnetic resonance imaging (MRI) may not be an option if non-MRI compatible
embolic agents have been used.
• Note: artifact from coils may limit the utility of CT and MRI.
a
Fig. 12.3 (a) Bleeding (white arrowhead) from the corona mortis branch of the internal obturator
artery (black arrows) following fracture of the pubic rami. (b) Following embolization, tightly
packed coils in internal obturator artery (black arrows) the end of the last coil has trailed into the
common femoral artery (white arrow). It was judged unlikely to lead to any problem and left where
it was
b
Catheters Blocking
This is a common, important, and sometimes preventable problem. A blocked
catheter may result in losing catheter position in a location accessed with great difficulty. Prevention is better than dealing with the consequences of a catheter that
cannot be unblocked and has to be totally removed and exchanged for another.
• Ensure that the lumen of the delivery catheter is appropriate for the selected coils
or other embolic agents (e.g., it is difficult to inject thick Gelfoam down a microcatheter, and it is impossible to pass a 0.038 “coil down a catheter with 0.035”
lumen).
126 L. Ratnam and R. Morgan
• Make sure coil introducers are held firmly in position in the catheter hub. Failure
to do so will result in the coil being partly deployed in the hub. Maldeployed coils
can usually be removed from the hub with a small pair of forceps.
• Remember that particles effectively narrow the catheter lumen.
• Frequently flush the catheter with saline. Use a 1-ml syringe to flush micro-
catheters.
• If a catheter does become blocked, then it may be safest to remove it. Forceful
injection to clear may dislodge embolic material that has already been delivered
and/or cause reflux into another vessel.
Non-target Embolization
It is important to recognize and record non-target embolization. The consequences
will depend on the following:
• Vascular bed: some tissues are more vulnerable and a small amount of embolization can cause a major clinical problem (e.g., large intestine, kidney, nerve, and
brain).
• Extent of the embolization: any tissue which is comprehensively embolized will
be damaged.
• The risk of non-target embolization is reduced by the use of microcatheters in
high-risk situations.
• In cases of coil migration, retrieval can be carried out if required.
If non-target embolization is likely to have clinical sequelae, then the patient
should be closely monitored for the development of complications.
Coil Retrieval
If the delivery catheter becomes displaced with a coil partially deployed, it may be
possible to
• Push the catheter back into position and try again.
• Pull the catheter back into the introducer sheath with the coil in situ—apply suc-
tion with a large syringe as you do this. The coil will usually lodge in the tip of
the sheath as the catheter is withdrawn. In this case, it can be snared close to the
puncture site.
Completely deployed coils and other foreign bodies can be retrieved using a
variety of commercially available devices.
• Loop snares, baskets, grasping forceps: these require a free segment of the coil to
grasp.
12 Complications of Embolotherapy 127
• Hook-shaped catheters: these can be used to manipulate a coil into a position
where it can be retrieved with a standard snare or basket.
Before attempting retrieval, consider pros and cons of leaving the coil where it is.
Every case should be assessed on its own merits. A decision to retrieve a migrated
coil is generally based on the following:
1. The location of the coil. The clinical situation is key here. A coil lodged in a
solitary calf artery is more important than a similar coil in a branch gluteal vessel.
2. The consequences of leaving it where it is. If the patient is asymptomatic
(Fig. 12.3) or the occlusion will not cause clinical sequelae, then the best course
of action may be conservative (e.g., leaving the coil where it is)!
3. The risks of attempting retrieval. Removal might lead to further problems;
complications of coil retrieval include
• Disturbing the rest of the coil nest and exacerbating the problem.
• Damaging other vessels: dissection, occlusion, spasm, rupture of the vessel
caused by manipulation of the retrieval device.
• Cardiac arrythmias if the coil has migrated to the heart.
• Embedding or further distal embolization of the agent that you are trying to
retrieve.
4. Timing. If retrieval is indicated, it is usually best to perform it immediately.
Occasionally it is better to delay retrieval or chose an alternative option.
5. Alternative options. It may be safer to remove a coil surgically, especially if the
embolization was performed pre-operatively.
6. The patient’s wishes. The patient should always give informed consent.
Tissue Necrosis
Following successful embolization, significant tissue necrosis or intravascular
thrombosis can result in the post-embolization syndrome. This must be distinguished from infection.
• Post-embolization syndrome is self-limiting (see Chapter 11).
• If symptoms persist or worsen, infection must be considered. In this case, blood
cultures should be performed.
Consider imaging to assess for abscess formation. Note that gas formation can
normally be seen following embolization of solid organs; in this instance, it is a
benign entity unrelated to the presence of infection.
Necrosis due to extravasation of liquid agents will be considered elsewhere.
128 L. Ratnam and R. Morgan
Keypoints
• Ensure that the indication for embolization is appropriate.
• Obtain fully informed consent.
• Careful planning of the procedure is essential.
• Review all available imaging before commencing procedure.
• Ensure all clinical information and imaging is up to date.
• Ensure adequate clinical back up is available should complications ensue.
• If necessary, discuss the case with an appropriate clinician/surgeon so that
they are aware that their support may be required.
Chapter 13
Management of Post-embolization Syndrome
Sapna Puppala
Introduction
• Post-embolization syndrome (PES) is a common side effect of solid organ
embolization.
• Clinical manifestations of PES are typically pain, fever, and sickness (nausea)
sometimes described as a flu-like illness.
• It is important to differentiate PES from infection and tumor lysis syndrome,
since these require different management.
• Occurrence and severity of PES cannot be predicted in any individual patient.
• Effective prevention and management of PES are crucial to fast patient recovery
and improve patient satisfaction and quality of life.
Pathophysiology
• The etiology of PES is not fully established.
• Tissue hypoxia and cell death lead to release of tissue breakdown products,
inflammatory mediators, and vasoactive substances from the tumor and adjacent
normal tissues.
• Radiofrequency ablation of tumors leads to a syndrome similar to PES typically
lasting 8–72 h and coinciding with the release of these bioactive substances.
• PES can continue up to 7–14 days post-procedure.
Clinical Features
The severity of symptoms can correlate with the volume of embolic agent and extent
of target tissue embolization, but this does not predict whether PES will occur
in any individual patient. The type of embolic agent does not correlate with the
occurrence of PES but small particles and liquid agents are more likely to result in
tissue necrosis. The key to success is to have flexible regimes to prevent and treat
symptoms.
Transcatheter Embolization and Therapy,
Techniques in Interventional Radiology, DOI 10.1007/978-1-84800-897-7_13,
C
Springer-Verlag London Limited 2010
129
130 S. Puppala
• PES affects children and adults.
• Symptoms: varying degrees of pain, fever, nausea, malaise, arthralgia, and loss
of appetite.
Pain
• Often characteristic pattern (e.g., uterine fibroid embolization (UAE)).
◦ 0–2 h: acute pain due to global uterine ischemia.
◦ 5–8 h: plateau phase.
◦ >8 h: rapid reduction due to resumption of blood flow to the myometrium.
• In 15–20% of patients after uterine fibroid embolization, this process can be more
pronounced. The cause for this variation is not known.
• Uncontrolled pain or high fever indicates other complications such as infection
and non-target embolization.
• Pain management must be flexible, responsive, and patient centred.
Fever
• Continuous or intermittent low-grade pyrexia <39◦C (104 F) is typical.
• High or spiking fever suggests infection.
Nausea and Vomiting
• Sickness is common secondary to PES and the use of opiate analgesia.
• Can lead to dehydration and electrolyte imbalance.
• Require supportive therapy: antiemetics and IV fluids.
Diagnostic Evaluation
Laboratory
White Cells
• 20% of patients with PES have leukocytosis <24,000/microlitre in the first 24 h.
• A later rise in leukocytes must be viewed with caution and suggests infection.
• Neutropenia may occur a few days after chemoembolization.
U&E
• Dehydration, contrast media toxicity, and release of toxic mediators can lead to
acute renal failure.
13 Management of Post-embolization Syndrome 131
Imaging
Imaging is not usually necessary and should be reserved for cases in which it is
necessary to exclude other pathology such as target organ infection and non-target
embolization.
• Pulmonary embolism through arterio-venous shunts can mimic PES and is
confirmed by ventilation/perfusion scan.
• For example, cystic artery embolization can lead to chemical cholecystitis
(Fig. 13.1) which significantly exaggerates the symptoms of PES and is assessed
by ultrasound and computed tomography (CT).
a
Fig. 13.1 Embolization of large hepatoma. (a) Collateral supply (white arrowheads) from a
branch of the cystic artery (black arrows). Retained Lipiodol is seen in the main tumor
(black arrowheads). (b) Following “selective” embolization of the branch artery, lipiodol is
seen in the gallbladder. The patient developed chemical cholecystitis which was managed
conservatively
b
Management of PES
Prevention
• Regimens involve pre-medication with analgesia, sedation, antiemetic therapy,
and hydration.