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186
A. M. Conway and R. J. Rosen
Table 16.1 Classication of vascular anomalies
Vascular tumors Vascular malformations
Benign Locally aggressive Malignant Simple or combined
Infantile
hemangioma
Congenital
hemangioma
Tufted hemangioma Papillary intralymphatic angioendothelioma
Spindle-cell
hemangioma
Epithelioid
hemangioma
Pyogenic granuloma
a
The four vascular anomalies that will be discussed in this chapter are in italics
Kaposiform hemangioendothelioma Angiosarcoma Capillary malformation
Retiform hemangioendothelioma Epithelioid
(PILA), Dabska tumor
Composite hemangioendothelioma Arteriovenous
Kaposi sarcoma Arteriovenous stula
a
Vascular anomalies
Lymphatic malformation
hemangioendothelioma
Venous malformation
malformation
Fig. 16.1 Typical infantile hemangioma (classic “strawberry birthmark”)
hemangiomas undergo a spontaneous, gradual, but extensive
involution. The diagnosis can be made on the history and
physical examination alone. The lesion appears as a nontender, slightly raised, bright-red lesion with well-dened
but irregular margins (Fig.16.1).
Vascular Malformations
Vascular malformations are congenital lesions, resulting
from a focal failure in embryonic angiogenesis. The result
ranges from high-ow arteriovenous connections to lowow lesions that may be venous, lymphatic, or a combination of both. These lesions are almost always isolated
anomalies in otherwise healthy individuals. A whole-body
work-up looking for additional lesions is not indicated,
nor is concern about other family members warranted.
Other than certain unusual familial syndromes such as
hereditary hemorrhagic telangiectasia (HHT), also known
as Osler-Weber-Rendu syndrome, they are generally not
inherited.
While vascular malformations are by denition congeni-
tal, they may not manifest until later in childhood or even
adulthood as they grow with the individual. Presentation can
vary depending on the size, ow, and location of the lesion.
Symptoms may be related to mass effect or a hemodynamic
effect on the affected circulation. A small lesion may have
signicant consequences if it is located near a vital structure
such as the eye or the airway. They may remain completely
asymptomatic or present as a mass, pain, bleeding, growth
disturbance, venous hypertension, ischemia, and, rarely,
high-output cardiac state or failure.
It is important to differentiate vascular malformations as
either high-ow or low-ow lesions. Arteriovenous malformations and arteriovenous stulae are examples of high-ow
lesions. Low-ow lesions include capillary, lymphatic, and
venous malformations.
Arteriovenous Malformations (High Flow)
High-ow AVMs produce a far greater hemodynamic affect
than low-ow venous malformations. The arteriovenous
shunting in high-ow AVMs lacks the normal resistance of
the capillary system and can cause signicant arterial steal
leading to distal ischemia (Fig.16.2) [6].
16 Vascular Malformations
187
Venous Malformations (Low Flow)
Low-ow venous malformations are some of the most common types of vascular malformations, with an overall prevalence of up to 1% in the general population [7]. They are
Fig. 16.2 Ischemic ulceration of the thumb in a patient with an AVM
(high ow)
composed of abnormal venous channels and can have a
spongy (“cavernous”) architecture. These lesions tend to
ll and empty depending on position and activity, and it is
this distension that usually accounts for the presenting
complaints of pain, heaviness, or swelling (Fig. 16.3).
Low-ow lesions may be isolated or seen as part of congenital syndromes such as Klippel-Trenaunay syndrome,
which is discussed separately later. Accelerated growth or
symptomatology of vascular malformations in female
patients may occur at the time of puberty or pregnancy; this
hormonally triggered growth is well documented but not
well understood. Trauma or surgical intervention may also
cause a previously stable lesion to show an increase in size
or symptoms.
Lymphatic Malformations
Lymphatic malformations can occur anywhere in the body
and can be macrocystic lesions (e.g., the classic cystic
hygroma in the neck) or microcystic lesions. They may also
be dened as inltrative lesions and cutaneous lesions
(Fig.16.4). In some patients, there can be low-ow lesions
with mixed venous and lymphatic components, known as
“venolymphatic malformations.” One of the hallmarks of
lymphatic lesions is their tendency for infection, with frequent fever and signs of cellulitis.
Fig. 16.3 Low-ow venous malformation involving the right chest
wall. Lesion is poorly dened, soft, compressible, and nonpulsatile
Fig. 16.4 T2 axial MRI of
the neck of two separate
patients demonstrating (a)
macrocystic lymphatic
malformation and (b)
microcystic lymphatic
malformation
Clinical Indication
Successful treatment of vascular malformations is dependent
on making an accurate diagnosis. A thorough history and
physical exam can aid in diagnosis prior to imaging.
Frequently, patients present with swelling that should be
assessed both in the supine and dependent position to assess
any dynamic impact on the lesion. High-ow AVMs may
have a palpable thrill and the skin will also feel warm to
touch. A bruit may be auscultated.
188
The diagnosis of low-ow venous malformations is generally simple when the lesion is accessible to physical examination, presenting as a soft, spongy mass that lls and
empties either by manual compression or change in dependency. If the lesion is supercial, a characteristic bluish discoloration may be noted; extremely supercial lesions may
also present with spontaneous ulceration and bleeding. No
pulsation or thrill is palpable, and these lesions are nontender except when complicated by the inammatory
changes of superimposed thrombosis. Bead-like nodules
(phleboliths) may be palpated, representing calcied sites of
prior thrombosis, which are clearly identied on plain lms
as rounded calcications and are pathognomonic of purely
venous malformations.
A. M. Conway and R. J. Rosen
Fig. 16.5 T1 axial MRI with contrast of an intramuscular venous mal-
formation involving the forearm. Findings typical of a well-dened
slow-ow lesion
Key Point
Phleboliths are calcied sites of prior venous thrombosis and can be palpated as bead-like nodules. These are
pathognomonic of a purely venous malformation.
To evaluate the characteristics of vascular malformations,
multiple imaging modalities are used. Conventional radiology has a limited role only providing information on phleboliths and bony changes if they exist. US with Doppler is
considered the imaging modality of choice for initial assessment and characterization of presumed vascular origin due to
its ease of accessibility and lack of radiation. It allows a
real- time visualization of the lesion with differential diagnosis between the high- and low-ow lesions. Due to rapid
acquisition time and temporal resolution with contrast
enhancement, multidetector CT is especially useful for AVM
lesions. MRI in combination with dynamic time-resolved
contrast material-enhanced MR angiography provides a
comprehensive assessment of vascular anomalies including
diagnosis with information on the hemodynamics, extension,
particularly deeper lesions, and anatomic relationship to
adjacent structures. At present, MR imaging is the most valuable modality for classication of vascular anomalies.
Images clearly show the low-ow mass as bright signal on
T1 and T2 sequences (Fig.16.5).
Conventional Therapy
Vascular malformations remain a difcult condition to treat.
In the latter quarter of the twentieth century, experience in
treating these conditions grew. Imaging studies such as MRI
and CT were crucial to gain understanding of the extent and
complexity of individual malformations [8]. Conventional
therapy consisted of surgical resection; however, this often
yielded poor results, with signicant morbidity. Widespread
resections led to damage on adjacent structures as well as
signicant blood loss. The recurrence rate was high and
amputations were frequently performed [9, 10].
Treatment of vascular malformations is a controversial
subject, compounded by the complex and variable nature of
these lesions. There is general agreement that asymptomatic,
stable malformations do not and may never require treatment
[11]. As time progresses, the combined effects of ischemia
from arterial steal in high-ow AVMs and venous hypertension may cause an asymptomatic lesion to become symptomatic warranting treatment.
Low-ow venous malformations typically consist of fragile vasculature that may be inltrative to surrounding structures. They have a spongy appearance, and any attempt at
surgical resection can lead to signicant blood loss. Careful
dissection is needed to avoid damage to adjacent structures.
High-ow AVMs were historically surgically resected; with
advances in endovascular techniques, preoperative embolization typically occurs in conjunction with surgical resection to
reduce ow through the nidus. Focal AVMs may be resected
with good results; however, diffuse lesions are more difcult
to treat [12]. Amputation may be required in extreme cases.
Although not a true vascular malformation, due to confusion among practitioners, the interventionalist will often be
called upon to assess hemangiomas. Endovascular interventions are rarely required and most are of cosmetic concern
only. In such occurrences, simple reassurance is all that is
needed. While corticosteroids were for many years the rst
line of treatment for problematic hemangiomas, there is
increasing use of the beta-blocker propranolol orally, which
has been shown to both inhibit the growth and accelerate
regression of these lesions [13].
Interventional Therapy
Interventional therapy has replaced traditional surgical resections as the principle management strategy for many vascular
malformations. While a cure may not always be achievable,
16 Vascular Malformations
189
signicant improvements in patients’ symptoms can be made.
Super-selective catheterization of feeding vessels, and the use
of embolic and sclerosing agents, has dramatically improved
our ability as interventionalists to treat these conditions.
Key Point
Patient expectations should be tempered as treatment
may require multiple procedures and cure is not always
achievable.
For the purposes of treatment, high-ow and low-ow
lesions can be considered as distinct entities and are discussed separately below.
High-Flow AVMs
Treatment for high-ow lesions is indicated when there is a
signicant mass, pain, bleeding, ischemia, growth disturbance, or high-output cardiac state. Preoperative imaging
includes ultrasonography, magnetic resonance angiography,
and/or CT angiography. Cosmetically disguring lesions
should be considered symptomatic, especially in children,
where there can be psychosocial consequences [14].
The goal in treating high-ow AVMs is to eliminate the
nidus. This low-pressure sump is the stimulus for recurrence
via collateral recruitment. The complexity of the arterial supply in most AVMs makes treating these lesions difcult, and
identication of the site of shunting is essential. Occluding
feeding vessels proximally should not be performed, as
while it may lead to an immediate satisfactory angiographic
result, collateral recruitment and recurrence of the lesion are
inevitable. Proximal occlusion makes the lesion increasingly
difcult to re-treat. The goal must be to penetrate and occlude
the actual nidus of the lesion [15].
There remains no ideal embolic agent for treating highow AVMs. Each available embolic agent compromises
patient safety, procedural efcacy, or both. Currently, both
particulate, including PVA particles or microspheres, and
liquid embolic agents are used. Sometimes these provide
only temporary results, with recurrences generally developing within weeks to months.
Liquid agents offer an alternative to particulates and have
been used as a treatment for AVMs for nearly 30years [16,
17]. Ethanol is a direct tissue toxin and works by causing
acute thrombosis and endothelial injury. Its use in AVM
embolization was rst reported in 1984 and has subsequently
been widely used clinically [18, 19]. It is a highly effective
agent but must be used with a great deal of caution due to its
intrinsic toxicity. The complications of ethanol include skin
necrosis, skin swelling, neuropathy, pulmonary artery spasm,
cardiac arrhythmia, and cardiopulmonary collapse [20, 21].
n-Butyl-2-cyanoacrylate (nBCA) is nontoxic and has the
ability to form a large vessel cast using small amounts of the
agent. It polymerizes almost instantaneously on contact with
any ionic medium, including saline, contrast, blood, and tissue. Intravascular acrylic adhesive nBCA “glue” is not as
potent an agent as ethanol and is less likely to completely
eradicate the lesion, but it has a much wider safety margin in
terms of complications.
Liquid embolic agent ethylene vinyl alcohol copolymer
(EVOH, e.g., Onyx, Medtronic, Minneapolis, MN, USA) has
shown signicant promise in treating high-ow lesions. Both
it and cyanoacrylate adhesives are only approved for cerebrovascular uses in the USA; nevertheless, there have been
several reports of good clinical results using EVOH elsewhere in the body in high-ow lesions [22].
Up to 20% of high-ow AVMs have a dominant outow
vein. An increasing number of reports have described the
transvenous approach to occlude outow veins [23, 24].
Occlusion of the venous outow reduces ow through the
nidus, leading to thrombosis.
The How To: High-Flow AVMs
1. The patient is typically placed under general endotracheal or laryngeal mask anesthesia, depending
on the location of the lesion and the need to control
respiration.
2. A prophylactic dose of antibiotics and steroids are
administered.
3. Arterial access is obtained using the Seldinger technique and a micropuncture kit (refer to Chap. 8 for
more information).
4. Angiography of the area of malformation is
performed.
5. Super-selective catheterization of arterial feeding
branches is performed to adequately visualize the
malformation.
6. The chosen embolic agents are prepared. nBCA is
low in viscosity and can be used through microcatheters. It can also be administered through 22G needles in direct puncture applications. A typical set up
16.6.
7. When using nBCA glue, the average deposition of
adhesive per injection ranges between 0.2 and
larger cast is obtained due to the incorporation of
16.7). When using different
embolic agents, the technique remains the same.
When selecting doses, the interventionalist should
refer to manufacturer’s guidelines.
8. Completion angiograms are performed.
190
Fig. 16.6 nBCA “glue”
setup includes separate
preparation area: (a) ethiodol
(for opacication and to slow
polymerization), (b) 5%
dextrose in water as a ush
solution, (c) nBCA adhesive
A. M. Conway and R. J. Rosen
Fig. 16.7 (a) Angiogram of lower extremity demonstrating high-ow
AVM of the foot supplied by branches of the anterior and posterior
tibial artery. (b) Direct puncture with administration of 0.2cc of nBCA.
Low-Flow Venous Malformations
Endovascular approaches to low-ow venous malformations
consist of forms of sclerotherapy. The goal is to thrombose
the lesion and damage the endothelial lining, so that when
the clot is reabsorbed, brosis develops. Early attempts to
embolize the normal-appearing arteries supplying the area of
the venous malformation were found to be ineffective. As
such, an arterial approach is not generally warranted.
The technique of direct puncture embolization is fairly simple and is an extension of the direct puncture technique rst
used to study these lesions [25]. The lesion is entered directly,
either with a sheathed or a micropuncture needle until blood
return is noted, which may be quite slow. Contrast is slowly
(c) Post-embolization angiogram showing reduced ow through the
AVM nidus with preservation of normal branches
hand injected under uoroscopic guidance, demonstrating
“uffy” appearing spaces of the venous malformation.
It is often necessary to use some sort of compression to
keep the sclerosant within the lesion. This can be done with
an automatic tourniquet applied to the extremity, inated
above diastolic but lower than systolic pressure. If the draining vein is accessible to direct compression, this can also be
done using a gloved hand or pressure with a surgical clamp.
Commonly used sclerosants include ethanol, sodium tetradecyl sulfate (STS), bleomycin, and doxycycline. STS
has gained popularity in recent years. It is prepared as
foam, which increases surface contact and sclerosant effect
[26]. STS also appears to have a reduced level of neurotoxicity and less likelihood of skin ulceration in comparison
with ethanol.
16 Vascular Malformations
The How To: Low-Flow Venous Malformations
1. The procedure is routinely performed under general
anesthesia.
2. An IV is placed distal to the lesion, and a dilute
solution of heparinized saline is continuously
infused. This reduces the risk of causing deep vein
thrombosis due to spillage of the sclerosant into the
deep system.
3. The lesion is entered with a 22G micropuncture nee-
4.
16.8). When the capacity of
the lesion has been reached, one or more normal-
which connect to the normal deep veins of the
anatomic region.
5. The sclerosing agent is then slowly injected under
As thrombosis occurs, the lesion will become
191
16.9).
kilogram is used when using ethanol.
6.
small amount of collagen suspension as each micropuncture needle is withdrawn, which not only provides hemostasis at the injection site but also reduces
the risk of ulceration due to the agent tracking back
to the skin entry site.
Postoperative care should include hydration and adequate
analgesia. Limb elevation to reduce swelling is routine in
low-ow malformations, and in some situations compression
may be used. A short multiday course of tapering steroids
can reduce the amount of swelling. Many patients can be
discharged the same day; however if there is concern for
swelling and any potential of compartment syndrome following embolization of an extremity malformation, then the
patient should be observed overnight. Hydration is essential
in this patient population to clear any hematuria caused by
hemolysis.
Treatment requires 4–6weeks to take full effect; therefore
if multiple treatments are necessary, they are typically spaced
6–8weeks apart. If symptoms persist, further interventions
can be performed. The total number of treatments is difcult
to predict but can range from one to over ten in extensive
cases with an average of three. Further imaging is necessitated by ongoing symptoms.
Complications include, but are not limited to, pain, swelling, blistering, and ulceration of the skin. Limiting the
Fig. 16.8 Fluoroscopic image of a direct puncture of a venous malfor-
mation of the lower extremity with a 22G micropuncture needle followed by contrast administration
Fig. 16.9 Sodium tetradecyl sulfate is now commonly used for sclero-
therapy of venous malformations. When prepared as foam (as above),
there is greater surface contact throughout the malformation and more
intense thrombosis
amount of contrast can reduce the potential for acute kidney
injury associated with contrast-induced nephropathy. One
should be aware of the potential for compartment syndrome,
especially when treating a malformation in the extremities.
Avoiding excessive treatment and contrast extravasation are
imperative.
192
Klippel-Trenaunay Syndrome
Klippel-Trenaunay syndrome (KTS), rst described in 1900,
is a well-known complex venous malformation that generally involves a single extremity, usually the leg [27]. The
syndrome is congenital but not genetically transmitted and
generally occurs in otherwise healthy individuals. It consists
of a cutaneous capillary malformation (“port wine stain”),
varicose veins, and limb hypertrophy. Hypoplasia of the normal deep system may be present. Bone and soft tissue abnormalities can also occur (Fig.16.10). Some patients will also
have a patent vena marginalis lateralis (“KT vein”), a persistent embryonic draining vein that ascends along the lateral
aspect of the leg and can be associated with reux and swelling due to lack of valves. The mildest forms of KTS appear
as unilateral varicose veins in an extremity, while the most
severe forms can extend into the pelvis and abdomen with
potentially life-threatening complications from bleeding.
Key Point
Klippel-Trenaunay syndrome consists of:
A. M. Conway and R. J. Rosen
• Port wine stain
• Varicose vines
• Limb hypertrophy, usually of a single leg
Treatment is difcult and usually conservative, consisting
of support stockings. Sclerotherapy can be effective to treat
symptomatic varicose veins and swelling locally. Endovenous
techniques (laser, radiofrequency ablation) have also been
used in treating the venous malformations, especially for
occluding the KT vein [28]. It is essential to image the status
of the deep venous system with ultrasonography or a
diagnostic venogram prior to any intervention, in order to
rule out a hypoplastic or absent deep venous system. Ablating
the abnormal channels in this setting may result in marked
worsening of the clinical situation.
Lymphatic Malformations
Lymphatic malformations are among the most difcult to
treat successfully. Large cystic lesions can be treated with
drainage and sclerotherapy. Standard sclerosants are typically used, specically doxycycline and bleomycin. More
supercial microcystic lesions may be amenable to resection
and skin grafting, as well as surface laser treatment.
Congenital lymphedema syndromes, which may occur with
or without focal lesions, are most effectively managed with
compression and massage therapy as well as custom-tted
support garments.
Fig. 16.10 Typical ndings of Klippel-Trenaunay syndrome
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Part IV
The Aorta
Abdominal andThoracic Aortic
Aneurysms
AndyLee andMichaelD.Dake
Pathophysiology
Abdominal Aortic Aneurysm (AAA)
The infrarenal abdominal aorta is considered aneurysmal if
the diameter measures >3cm or ≥1.5 times the normal diameter [1]. Aneurysm rupture is associated with a high morbidity and mortality; 30–50% of patients die prior to being able
to undergo treatment, frequently before even reaching the
emergency department [2–4]. Parkinson etal. reported that
only 42% of those that are treated actually survive the postoperative period [5]. Accounting for approximately 15,000
deaths per year in the United States, the associated high mortality of rupture has been inuential in our current screening,
medical and operative management, and guidelines for
approaching abdominal aortic aneurysms [1, 6].
While the exact mechanisms of AAA formation remain
unclear, atherosclerosis often plays a causative role in AAA
formation [7]. Atherosclerotic changes initiate a remodeling
process in the extracellular matrix and adventitial components of the vessel wall that involves various inammatory
pathways, matrix degradation, thrombosis, hemodynamic
forces, and a host of associated signaling molecules in AAA
pathogenesis [8, 9].
Substantial research has also corroborated the involvement of environmental, hemodynamic, and immunological
factors in the development of aneurysms [10]. The rst clear
A. Lee
Beth Israel Deaconess Medical Center, Department of Vascular
Surgery, Boston, MA, USA
e-mail: alee10@bidmc.harvard.edu
M. D. Dake (
Stanford University Medical Center, Department of Cardiothoracic
Surgery, Stanford, CA, USA
e-mail: mddake@stanford.edu
*)
17
association between smoking and aneurysm formation was
attributed to the Framingham study in 1969 [11]. In fact,
cigarette smoking is the risk factor most strongly associated
with aneurysm development, rupture, and expansion. The
2009 practice guidelines from the Society for Vascular
Surgery note that there is strong evidence that smoking cessation reduces the risk of AAA growth and rupture [12]. At
the present time, smoking cessation should be considered
one of the most important recommendations to decrease the
rate of aneurysm expansion [13]. This illustrates the molecular and multifactorial complexity of aneurysm formation
while providing a target for medical directed therapy.
Key Point
Cigarette smoking is strongly associated with aneurysm formation. Smoking cessation is one of the most
important recommendations to decrease the rate of
aneurysm expansion.
Abdominal aortic aneurysms can be categorized into
four subtypes based on the proximal extent: suprarenal,
pararenal, juxtarenal, and infrarenal (Fig.17.1). Suprarenal
aneurysms extend above the renals and involve the origin
of one or more of the visceral arteries but do not extend into
the chest. Pararenal aneurysms involve the renal arteries
but the superior mesenteric artery is non-aneurysmal.
Juxtarenal aneurysms originate just distal to the origin of
the renal arteries on the aorta. There is generally no aneurysm-free aorta between the renal arteries and origin of the
aneurysm. Infrarenal aneurysms, the easiest to treat endovascularly, have a ≥1 cm non-aneurysmal segment or
“neck” of aorta distal to the renal arteries prior to the aneurysm [14]. There are also classication systems for describing the degree of distal extent into the common or internal
iliac arteries.
© Springer International Publishing AG, part of Springer Nature 2018
N. A. Keefe et al. (eds.), IR Playbook, https://doi.org/10.1007/978-3-319-71300-7_17
197