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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3869_Библиотеки_им_академика_М_И_Перельмана.pdf
14 Peripheral Vascular Malformations 143
Post-embolization
• Compression of the puncture site post-sclerotherapy until hemostasis achieved.
• The patient is reviewed 1 h post-treatment, and can generally then be discharged.
• Normal post-GA discharge protocol if applicable.
• A short course of steroids are given if a head and neck lesion is treated.
Follow-Up
• Follow-up and repeat treatments are carried out every 6–8 weeks to allow any
post-sclerotherapy inflammatory reaction to settle.
High-Flow Lesions
Diagnostic Evaluation
Clinical Review
• Clinical evaluation combines history, clinical examination, and ultrasound
assessment.
Laboratory
• It is important to check the platelet count in patients with very large vascular malformations as they can be consumptive and are associated with a
thrombocytopenia.
• Hemoglobin and clotting parameters are important if intervention is planned.
Imaging
• Ultrasound Doppler can demonstrate arterialized flow with abnormal veins in an
arteriovenous malformation, differentiating it from a venous malformation.
• MRI is used to demonstrate the lesion, including the arterial and venous anatomy.
Indications for Embolization
• Significant pain, swelling, or aesthetic appearance.
• Cardiac failure (generally in pelvic AVMs) and peripheral ischemia due to
shunting can occur in high-flow lesions and are indications for treatment.
• Platelet consumption.
Alternative Therapies
• Conservative management: if the patient is relatively asymptomatic.
• Surgical resection: best for small superficial lesions. Frequent recurrence is a
problem.
144 P. Littler and P. Rowlands
Cautions/Contraindications
• Patent foramen ovale or other right-to-left shunts are relative contraindications.
• Non-target embolization: this can result in limb loss when treating digits.
Anatomy
• Dependent on site.
Equipment
Catheters
• Non-selective catheters: standard angiographic catheters.
• Selective catheters: including a microcatheter for selective embolization.
• Guide catheter as needed.
• Occlusion balloons for venous outflow.
Embolic Agents
• Coils: sized appropriately for the target vessel
• Glue
• Particles (polyvinyl alcohol 350–500 μm)
• Onyx
Medication
• Pain control: simple analgesia as required post-procedure.
Angiography
Access
• Usually arterial approach, commonly via the common femoral artery.
• Percutaneous direct puncture.
• Venous approach in arteriovenous lesions. This may also be necessary to occlude
the venous outflow during transarterial embolization.
Angiography
• Multiple non-selective, selective, and superselective angiograms are performed
in different planes to find the nidus of the AVM. High frame rates and multiple
14 Peripheral Vascular Malformations 145
projections are often needed for the accurate identification of the nidus. This is
crucial to successful treatment.
Assessing the Lesion
Angiographic Appearance
• Selective angiography via the feeding arteries reveals the nidus of the AVM.
Rapid filling of the draining veins is s een (see Fig. 14.4).
(a)
(b)
(c)
Fig. 14.4 (a) Selective angiogram of a pelvic AVM demonstrating the feeding vessels and nidus
(arrow), (b) venous phase of the angiogram and (c) the nidus being treated with Onyx
Treatment Plan and Technique
• Successful treatment requires obliteration of the nidus.
146 P. Littler and P. Rowlands
• Liquid/particulate agents are essential for this. Proximal coil embolization will
inevitably lead to recurrence.
• The embolic agent is delivered as close as possible to the level of the AV shunt.
This must be done accurately to avoid non-target embolization.
• Arteriovenous lesions have a solitary venous component and can be embolized
via the draining vein or via direct puncture.
• It is often necessary to occlude the venous outflow to reduce flow and prevent
systemic migration of the embolic agent. This can be achieved with an occlusion
balloon to transiently occlude the shunt or permanently occlude with coils.
• Particle embolization may be used to devascularize lesions prior to surgical
debulking.
Post-embolization
• Standard care post-arterial puncture.
• For direct AVM puncture-wound site observation and regular blood pressure and
pulse checks.
Follow-Up
• Repeated treatments may be required as determined by follow-up clinical and
imaging assessment.
Keypoints
• Differentiation into high-flow arteriovenous and low-flow venous malformation is vital as treatment is different for each group.
• This can be achieved by clinical examination, ultrasound, and MRI
assessment.
• These conditions are rarely life threatening. Therefore a risk/benefit
evaluation prior to treatment is important.
• Treatment should be carried out by a specialist in the field working as part
of a multidisciplinary team.
Safety
• Accurate deployment of the sclerosant or embolic agent is crucial to
minimize the risks of complications.
Chapter 15
Pulmonary Arteriovenous Malformations
Graham Robinson
Clinical Features
Like all arteriovenous malformations, pulmonary arteriovenous malformations
(PAVM) “steal, shunt, or bleed.” PAVMs are important as systemic venous blood
can bypass the lungs, leading to hypoxia or paradoxical embolism. PAVMs tend to
increase in size with time.
Clinical Presentation
• Transient ischemic attack (TIA)/stroke or cerebral abscess from paradoxical
embolization.
• Shortness of breath if large shunt.
• Incidental “mass” on chest radiograph.
• Screening in hereditary hemorrhagic telangiectasia (HHT) (Fig. 15.1).
• Hemoptysis
Fig. 15.1 Typical
telangectasia on the lips of a
lady with HHT and PAVM
Transcatheter Embolization and Therapy,
Techniques in Interventional Radiology, DOI 10.1007/978-1-84800-897-7_15,
C
Springer-Verlag London Limited 2010
147
148 G. Robinson
Clinical Relevance
• Untreated PAVMs carry a 1% stroke and 0.5% brain abscess risk per annum.
Risk does not correlate well with the size of the shunt. Most patients have a small
number of localized pulmonary AVMs; up to 5% of patients have a diffuse pattern
with multiple lesions (Fig. 15.2).
Fig. 15.2 Twenty-one-year-
old man with diffuse PAVMs.
There are extensive PAVMs
throughout the right lung.
Note coils in lower lobe from
previous embolization (black
arrows)
• 70–90% of patients with pulmonary AVMs have underlying HHT; relatives should be screened for HHT (and pulmonary AVMs if positive
for HHT).
• HHT is an autosomal dominant condition with variable penetrance, and an incidence of 1 in 6,000–10,000. There are five types described, with type 1 having
the highest association with pulmonary AVMs (approximately 30%). Pulmonary
AVMs do tend to run in families.
15 Pulmonary Arteriovenous Malformations 149
Diagnostic Evaluation
Clinical
Multidisciplinary team with chest physician, ENT, neurologist, gastroenterologist,
and clinical genetecist. The importance of screening family members cannot be
overemphasized.
Laboratory
Hemoglobin, routine biochemistry.
Oxygen saturation/blood gas analysis if breathless.
Blood cultures if cerebral or paradoxical abscess.
Imaging
Non-contrast chest CT. There is a risk of paradoxical air embolus in untreated
pulmonary AVMs, so no cannulae or intravenous injections unless absolutely
necessary.
Reformatted multislice CT gives a good appreciation of pulmonary AVM
anatomy.
Contrast-enhanced CT (performed under supervision) or pulmonary angiography
may be helpful in complex lesions and in planning embolization (Fig. 15.3).
Fig. 15.3 CECT was helpful for planning intervention in this 25-year-old lady presented with
life-threatening hemothorax. The reformats show feeding and draining vessels and an unsuspected
second component
150 G. Robinson
Indications
• Any symptomatic PAVM regardless of size of feeding vessel
◦ Feeding arteries as small as 2–2.5 mm have caused symptoms.
• Asymptomatic PAVM
◦ There is no published evidence correlating the size of the feeding artery with
stroke risk.
◦ Many authors recommend treating lesions with feeding arteries of >3 mm.
◦ If treating smaller lesions, use common sense—the risk of treating small
lesions that are technically challenging to catheterize may well be greater than
leaving them for a later day when they will be a little larger.
Alternative Therapies
Surgical resection was all that was available until 1977, but has been largely replaced
by embolotherapy.
Contraindications
• Severe pulmonary arterial hypertension is a relative contraindication. Recent
work shows no consistent response to embolization, with increased pressures in
some patients post-procedure and decreases in others. Involvement of a chest
physician with an appropriate interest is advisable.
• Usual relative contraindications of contrast allergy, inability to lie still/cooperate
with breathing instructions.
Specific Complications
• Stroke: the risk of stroke must be discussed and recorded. This is particularly
sensitive in asymptomatic patients. It is often helpful to involve both the patients
and their relatives.
• Pleuritic pain: in some patients, it may be almost impossible to avoid some pul-
monary infarction during embolization of PAVM, with a risk of post-procedural
pleuritic pain.
Anatomy
A comprehensive knowledge of pulmonary vascular anatomy is a vital pre-requisite
for undertaking this procedure.
15 Pulmonary Arteriovenous Malformations 151
Equipment
Catheters
• Non-selective catheters: 100-cm pigtail catheter, capable of flow rates of 20 ml/s
for pulmonary angiography. (There are angled pigtails such as the Grollman
catheter specifically designed for pulmonary angiography.)
Remember always to straighten out the pigtail with a guidewire before removing
the catheter after pulmonary angiography. This prevents engagement of the valves
and chordae tendinae.
Selective Catheters
• Shaped catheter of choice to negotiate through right heart (e.g., angled pigtail,
Berenstein, Cobra). Catheters should be at least 80 cm long.
Guide catheter
• Personal preference is important. Make sure that it is at least 80 cm long and of
suitable diameter.
• Lumax (Cook) coaxial catheter with 7F 80 cm outer and 5F 100 cm hydrophilic
Berenstein-type shaped inner, or 8F 90 cm outer with 110 cm inner. The 8F is
stiffer and less easy to manipulate—only used when large Amplatzer vascular
plugs (AVPs) are to be utilized.
• Some operators use a sheath rather than guide catheter. Use whatever you are
most familiar and comfortable with.
Embolic Agents
• Coils—regular/micro, pushable/detachable. Fibered coils are more thrombogenic
and usually preferred over non-fibered.
• Amplatzer vascular plugs of appropriate size assessed from pre-procedure imaging (types 1, 2).
• Guglielmi or other detachable coils.
Medication
• Pain control: not usually necessary. Symptomatic therapy in case of pleu-
ritic chest pain. Non-steriodal anti-inflammatory drugs are usually all that are
required.
• Infection control: no routine antibiotics.
• Sickness control: not routinely.
• Hydration: not routinely.
152 G. Robinson
Angiography
Access
• Right femoral vein.
• Can use jugular approach if required (e.g., IVC thrombus) or preferred.
• Can go through a patent IVC filter, if well incorporated into the IVC wall.
Angiography
• Measure main pulmonary artery pressures (PAP) prior to injecting contrast. Do
not perform pump runs if PAP >40 mmHg.
• The catheter passes into the left pulmonary artery in most patients, since this
vessel courses more posteriorly (this is akin to catheters passing into the splenic
artery in preference to the hepatic artery).
• A variety of techniques can be used to select the right pulmonary artery, including
prolapse of the floppy end of a Bentson wire, use of a hydrophilic wire, the stiff
end of a regular wire to open out the pigtail of a pulmonary pigtail catheter, use
of a tip-deflecting wire, or exchange for a multipurpose shape.
• High frame rates (6/sec or more) may be needed to visualize the feeding vessels
accurately.
Assessing the Lesion
Non-selective main or lobar injections initially, if no prior angiography.
Proximal (pulmonary trunk) injections risk missing peripheral lesions (Fig. 15.4)
Angiographic Appearance
Localizing precise anatomy of feeding vessel(s) vital. This may require patience and
multiple oblique projections. Biplane angiography is sometimes helpful.
Treatment Plan and Technique
• Aim to occlude the feeding artery as close to the aneurysm sac as possible, as
this reduces the risk of reperfusion by collateral feeders and minimizes the risk
of pulmonary infarction.
• Aim for a tight coil pack and cross-sectional occlusion.
• The s elected embolic device needs to be large enough to occlude the target vessel.
If too small, there is a risk of paradoxical embolization into the systemic circulation. Having a team member ready to apply bilateral carotid compression if a