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21 Bronchial Artery Embolization
Fig. 21.2 (a) Angiogram depicts a hypertrophic orthotopic right intercostobronchial trunk. (b) Angiogram of a common trunk bronchial artery
which supplies both the right and left lungs
241
Fig. 21.3 Anterior spinal artery arising from a left intercostal artery at
the T10 level and demonstrating the classic hairpin turn
artery. The hairpin loop appearance of these contributing
branches is a common description. The anterior medullary
branch is the largest branch, also known as the artery of
Adamkiewicz. The artery of Adamkiewicz can arise anywhere from T8 through L1, but in about 5% of patients, this
artery may originate from the right intercostobronchial trunk
(Fig.21.3). Although the traditional teaching has been that
the left bronchial artery rarely contributes blood supply to
the anterior spinal artery, there have been reported cases in
which the spinal artery has been shown to arise from a left
bronchial artery. Given these considerations it is important
that a neurological examination be performed prior to any
bronchial artery embolization so as to document a neurological baseline status.
Clinical Indication
Because the diagnosis of massive hemoptysis or of major
hemorrhage is a purely clinical one, obtaining a good clinical
history is important in planning appropriate management.
The history should include an assessment of the frequency
and severity of the hemoptysis, any element of respiratory
impairment, and any information that might determine the
etiology, such as known underlying chronic lung disease.
Often patients with massive hemoptysis are able to lateralize
the side of bleeding and can describe an abnormal sensation
on a particular side of the hemithorax. The physical examination should evaluate for any evidence of respiratory distress such as tachypnea or tachycardia and should include
auscultation to assess for wheezing or decreased breath
sounds. Useful laboratory parameters include hemoglobin
and hematocrit, to evaluate the degree of blood loss, white
blood cell count with differential to assess for underlying
infection, coagulation prole, and renal function testing. The
latter two laboratory parameters are important pre- procedural
data to have in any patient in whom an arteriogram and
catheter- based intervention are being considered.
242
Fig. 21.4 CTA. (a) Coronal
image shows the origin of a
large right intercostobronchial
trunk arising from the
thoracic aorta. (b) Additional
coronal image from this CTA
reveals a “ring of worms”
pattern in the mediastinum,
which is due to the
hypertrophic and tortuous
conguration of these
abnormal bronchial arteries.
(c, d) Axial images show
extensive areas of
bronchiectasis with adjacent
abnormal bronchial arteries
L. I. Valentin and T. G. Walker
Computed tomographic angiography (CTA) is recognized
as the best noninvasive imaging modality for the evaluation
of massive hemoptysis [8–13]. CTA is typically very useful
as it can often identify the underlying etiology of the hemoptysis; can demonstrate bronchial arterial anatomy and any
suspicious vessels, along with their points of origin; and can
thereby assist in pre-procedural planning. However, this
examination does not usually conrm which bronchial artery
is bleeding (i.e., laterality) and has no therapeutic role in
management (Fig.21.4).
Therefore, other more invasive diagnostic modalities play
central roles in the evaluation and management of a patient
with hemoptysis. Fiber-optic bronchoscopy can help by conrming a bronchial etiology for the hemorrhage (91%), identifying laterality in up to 95% of patients, and even treating
the source of hemoptysis in some cases [14]. In those patients
in which bronchoscopy has identied a bleeding source but
cannot adequately control the ongoing bleeding, angiography is almost always indicated. Angiography can be both
diagnostic and therapeutic. The typical angiographic appearance of an abnormal bronchial artery is that of one or more
enlarged, hypertrophic, and tortuous vessels extending along
the tracheobronchial tree into an extensive area of patchy
hypervascularity. There may also be evidence of arteriovenous shunting or less often pseudoaneurysms may be present. Active bleeding, as manifested by contrast extravasation,
is infrequently seen (Fig.21.5).
After performing diagnostic bronchial arteriography, the
interventionalist can proceed to embolize the bronchial arteries during the same session. It should be noted that a history
of previous embolization does not preclude additional or
repeat embolization treatment. There are several possible
treatment algorithms for managing hemoptysis (Fig.21.6).
Conventional Therapy
Conservative medical management as the sole treatment for
massive hemoptysis carries a very high mortality rate of
50–85% [15]. Surgical and bronchoscopic methods are used
for management in the minority of cases; with advances in
endovascular techniques, bronchial artery embolization has
become the standard treatment. While surgery may be an
option in individuals who have focal disease, most patients
21 Bronchial Artery Embolization
243
Fig. 21.5 (a) Bronchial artery pseudoaneurysm in a patient with tuber-
culosis. (b) Selective coil embolization of the bronchial artery pseudoaneurysm. (c) Appearance of remaining distal bronchial artery branches
Fig. 21.6 Sample algorithm for massive hemoptysis. Key aspects include history and physical examination to determine if patient is stable or
unstable, stopping any inciting medicines, CTA, and use of a multidisciplinary approach in cases in which more than one option can be considered
following coil embolization. (d) There is an additional right bronchial
artery originating from a lower level in the thoracic aorta on the same
patient
244
who present with massive hemoptysis have underlying diffuse and chronic lung disease that often makes them poor
surgical candidates with high morbidity and mortality. Since
approximately 95% of cases of massive hemoptysis will be
related to the bronchial arterial system, transcatheter therapy
is now recognized as the gold standard or rst-line therapy in
most cases [16].
Interventional Therapy
Bronchial artery embolization (BAE) is a minimally invasive image-guided transcatheter treatment that is used to
intentionally occlude abnormal and hypertrophied bronchial
arteries with the aim of controlling massive hemoptysis. It
was originally introduced in France by Remy etal. in 1973
[6], which was followed closely in the United States by
Wholey etal. [4]. It has since become the mainstay of therapy for the management of massive hemoptysis. The goal of
treatment is to achieve temporizing or palliative control.
Completely curative treatment requires addressing the
underlying lung disease via surgical or medical means.
Contraindications to BAE include a non-bronchial artery
source of bleeding such as the pulmonary artery and history
of severe contrast allergy. BAE may be performed in the
emergent setting. The patient must have a satisfactory airway status via general anesthesia or IV conscious section.
This may require unilateral selective main stem bronchial
intubation in select cases. Pre-procedural labs should be
optimized.
L. I. Valentin and T. G. Walker
used for this purpose are either curved, such as a
cobra, or reverse-curved such as a SOS, Simmons, or
Mikaelsson. Some operators recommend that the
vessel origin and thereby increase the likelihood of
identifying any spinal arterial supply.
5. Advance a microcatheter coaxially through the parent
catheter, and position the catheter tip distal to the
bronchial artery origin. This microcatheter tip position
is important, as it is intended to minimize the
that could result in nontarget embolization.
6.
perform embolization through the microcatheter.
The most commonly used embolic agents are solid
microspheres. Mixing the embolic agent with the
liquid contrast medium allows direct visualization
during injection. Coils are not routinely used for
bronchial artery embolization unless there is a
need to treat an aneurysm or pseudoaneurysm or
for treatment of a recruited non-bronchial collateral. Liquid embolic agents such as absolute alcohol and very small particles are avoided due to the
risk of ischemia/infarction with extremely distal
embolization.
7. The embolization end point is generally felt to have
been reached once there is no longer forward intra-
The How To
1. Obtain arterial access via a transfemoral or transradial approach using the Seldinger technique
(refer to Chap. 8 for more information). Place an
intravascular arterial access sheath.
2. tion the catheter tip in the transverse or descending
thoracic aorta. Perform digital subtraction angiography (DSA) of the thoracic aorta. A thoracic aortogram may be unnecessary if detailed bronchial and
(e.g., shown by prior angiography or other imaging
such as CTA).
3. Identify bronchial arterial anatomy (i.e., origin,
number, and course). Identify any systemic arterial
recruitment such as internal mammary or other
21.7).
4. Use a 4 or 5 French catheter (parent catheter) to
selectively catheterize a bronchial artery and perform
particles, i.e., stasis has been achieved. At this point
any additional injection of the embolic agent would
21.8).
Outcomes
The expected outcome of a BAE is the control of hemoptysis
manifested as complete cessation of the expectoration of
bloody sputum. Reported recurrence rates at 1month range
from 2% to 27%, and long-term recurrence rates up to
46 months are reported in the range of 10–52% [17].
Recurrent hemoptysis after BAE can be caused by incomplete embolization, failure to identify and embolize all bronchial arteries, arterial collateralization from other vascular
territories including systemic arteries, and recanalization of
the embolized bronchial artery. Of note, however, BAE can
21 Bronchial Artery Embolization
245
Fig. 21.7 (a) DSA in a patient with massive hemoptysis shows a col-
lateral network (black arrow) extending cephalad from the right bronchial artery (white arrow). (b) A right subclavian artery DSA
demonstrates that the collateral (black arrow) arises from the systemic
Fig. 21.8 (a) DSA shows a typical abnormal bronchial arteriogram.
The bronchial artery is hypertrophied, with a diameter that exceeds
2mm, and is tortuous. Distally, there is a hypervascular blush and there
are additional tortuous bronchial arteries, but no contrast extravasation.
The latter is infrequently seen, occurring in less than 10% of cases. (b)
The embolization end point is reached when there is stasis of ow within
the bronchial artery, without retrograde reux of the embolic mixture
be repeated in cases of recurrent hemoptysis, with very good
success rates. In cases in which there is recurrence of hemoptysis shortly after BAE, one should carefully investigate for
previously unidentied and untreated orthotopic or ectopic
bronchial arteries as well as for systemic arterial collaterals
that may be the culprit vessel(s). Recent data has shown that
dedicated multidetector CTA of the bronchial arterial anatomy is very useful in identifying such vessels and in directing subsequent repeat BAE [18].
circulation as a branch of the thyrocervical trunk. Systemic collaterals
may contribute perfusion to abnormal pulmonary parenchyma that is
normally supplied only by the bronchial arteries. This typically occurs
when the inammatory process extends to involve the pleural surfaces
Key Point
Recurrent hemoptysis following BAE causes:
• Incomplete embolization
• Arterial collateralization (systemic source of
recanalization)
• Failure to identify and embolize all bronchial
arteries
The most frequently occurring morbidity events that are
associated with BAE are transient chest pain and/or dysphagia, most likely resulting from occlusion of intercostal or
esophageal arterial branches. These events are usually selflimited and are managed conservatively with analgesics. The
most feared complication of BAE is transverse myelitis,
resulting from spinal cord ischemia. This occurs as a consequence of inadvertent iatrogenic embolization of arterial
branches supplying the spinal cord. Although the reported
incidence ranges from 1.4% to 6.5%, this data includes some
of the early BAE experience in which coaxial microcatheter
systems were not routinely used for super-selective embolization [17]. It is now generally felt that the incidence of this
complication is at the lower end of the reported range.
Overall, BAE should be considered to be a very safe procedure when performed by an experienced operator who is
thoroughly familiar with both the bronchial arterial anatomy
and the potential pitfalls associated with the procedure.
246
Key Point
Complications following BAE:
• Chest pain (intercostal artery embolization)
• Dysphagia (esophageal artery embolization)
• Transverse myelitis (spinal artery embolization)
References
1. Kalva SP.Bronchial artery embolization. Tech Vasc Interv Radiol.
2009;12(2):130–8.
2. Stoll JF, Bettmann MA. Bronchial artery embolization to
control hemoptysis: a review. Cardiovasc Intervent Radiol.
1988;11(5):263–9.
3. Viamonte M.Selective bronchial arteriography in man. Radiology.
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4. Wholey MH, Chamorro HA, Rao G, Ford WB, Miller
WH. Bronchial artery embolization for massive hemoptysis.
JAMA. 1976;236(22):2501–4.
5. Rémy J, Arnaud A, Fardou H, Giraud R, Voisin C. Treatment of
hemoptysis by embolization of bronchial arteries. Radiology.
1977;122(1):33–7.
6. Remy J, Deschildre F, Artaud D, Remy-Jardin M, Copin MC, Bordet
R, etal. Bronchial arteries in the pig before and after permanent
pulmonary artery occlusion. Investig Radiol. 1997;32(4):218–24.
7. Tom LM, Palevsky HI, Holsclaw DS, Trerotola SO, Dagli M,
Mondschein JI, etal. Recurrent bleeding, survival, and longitudinal pulmonary function following bronchial artery embolization
for hemoptysis in a U.S. adult population. J Vasc Interv Radiol.
2015;26(12):1806–13.
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8. Remy-Jardin M, Bouaziz N, Dumont P, Brillet P-Y, Bruzzi J, Remy
J. Bronchial and nonbronchial systemic arteries at multi-detector
row CT angiography: comparison with conventional angiography.
Radiology. 2004;233(3):741–9.
9. Yoon YC, Lee KS, Jeong YJ, Shin SW, Chung MJ, Kwon
OJ. Hemoptysis: bronchial and nonbronchial systemic arteries at
16-detector row CT.Radiology. 2005;234(1):292–8.
10. Do KH, Goo JM, Im JG, Kim KW, Chung JW, Park JH.Systemic
arterial supply to the lungs in adults: spiral CT ndings.
Radiographics. 2001;21(2):387–402.
11. Yoon W, Kim YH, Kim JK, Kim YC, Park JG, Kang HK.Massive
hemoptysis: prediction of nonbronchial systemic arterial supply
with chest CT.Radiology. 2003;227(1):232–8.
12. Furuse M, Saito K, Kunieda E, Aihara T, Touei H, Ohara T, etal.
Bronchial arteries: CT demonstration with arteriographic correlation. Radiology. 1987;162(2):393–8.
13. Bruzzi JF, Remy-Jardin M, Delhaye D, Teisseire A, Khalil C,
Remy J. Multi-Detector Row CT of hemoptysis. Radiographics.
2006;26(1):3–22.
14. Saumench J, Escarrabill J, Padró L, Montañá J, Clariana A,
Cantó A.Value of beroptic bronchoscopy and angiography for
diagnosis of the bleeding site in hemoptysis. Ann Thorac Surg.
1989;48(2):272–4.
15. Yoon W, Kim JK, Kim YH, Chung TW, Kang HK. Bronchial
and nonbronchial systemic artery embolization for lifethreatening hemoptysis: a comprehensive review. Radiographics.
2002;22(6):1395–409.
16. Sopko DR, Smith TP. Bronchial artery embolization for hemoptysis. Semin Intervent Radiol. 2011;28(1):48–62.
17. Ittrich H, Klose H, Adam G.Radiologic management of haemoptysis: diagnostic and interventional bronchial arterial embolisation.
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18. Zhao T, Wang S, Zheng L, Jia Z, Yang Y, Wang W, etal. The value
of 320-row multidetector CT bronchial arteriography in recurrent
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Interv Radiol. 1987;15:1–10.
Pulmonary Angiography: Arteriovenous
Malformation andPseudoaneurysm
JereyS.Pollak
Pathophysiology
Pulmonary Arteriovenous Malformation
Pulmonary arteriovenous malformations (PAVMs) consist
of dilated vascular channels directly connecting pulmonary
arteries and veins without an intervening capillary bed.
They are typically congenital although can also be secondary to acquired arteriovenous stulae. The autosomal dominant disorder hereditary hemorrhagic telangiectasia (HHT)
has been reported in 56–97% of patients with congenital
PAVM and needs to be considered in patients with PAVM as
it can be underdiagnosed [1–6]. Spontaneous PAVM
accounts for a small minority. Women are slightly more
aficted than men. Acquired pulmonary arteriovenous stulae are generally less signicant clinically. These may be
seen with hepatopulmonary syndrome (typically with
microscopic lesion), cavopulmonary anastomoses for cyanotic congenital heart disease, and less commonly with
schistosomiasis, actinomycosis, hypervascular metastatic
cancer, amyloidosis, Fanconi’s syndrome, trauma, or erosion of an aneurysm into a vein [7–10].
Hereditary hemorrhagic telangiectasia or Osler-WeberRendu syndrome causes alterations in vasculogenesis and
vessel wall structure that result in arteriovenous malformations (AVMs) of variable size in multiple organs, most visibly as mucocutaneous telangiectases (Fig.22.1) [11, 12]. A
clinical diagnosis is made if three of four criteria are present
while it is possible with two criteria and unlikely with only
one (Table 22.1). The prevalence is 1in 5,000–8,000, with
penetration variable but increasing with age [11, 13].
22
Fig. 22.1 Multiple telangiectasias on the tongue and lips in a patient
with HHT
Table 22.1 Clinical criteria for the diagnosis of hereditary hemorrhagic
telangiectasia
1. Multiple telangiectases of the skin and mucous membranes,
especially at characteristic sites such as the ngers, lips, oral
cavity, and nose
2. Repeated episodes of spontaneous epistaxis
3. A typical visceral vascular malformation, consisting of
pulmonary AVM, central nervous system AVM, liver AVM, and
gastrointestinal tract telangiectases or a larger AVM
4. HHT present in a rst-degree relative
Key Point
Most pulmonary arteriovenous malformations occur in
patients with the genetic condition hereditary hemorrhagic telangiectasia, and the incidence of PAVM in
HHT is 23–61%.
J. S. Pollak (*)
Yale University School of Medicine and Yale-New Haven Hospital,
Department of Radiology and Biomedical Imaging, Section of
Vascular and Interventional Radiology, New Haven, CT, USA
e-mail: Jeffrey.Pollak@yale.edu
© 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_22
Three denite genetic types of HHT have been identied,
with the genes coding for proteins involved with transforming
growth factor-ß signal transduction [14–20]. Type 1 is caused by
mutations in ENG, which produces endoglin, and type 2 is
247
248
J. S. Pollak
caused by mutations in ACVRL1 (or ALK1), which produces
activin receptor-like kinase 1. These two are responsible for
73–93% of cases. The third type accounts for 2–3% and is caused
by mutations in SMAD4, which is also one of the two genes
causing juvenile polyposis, thereby resulting in the combined
syndrome of JP-HHT [21]. Overall, genetic testing is positive in
63–93%, so a negative result does not exclude HHT, but when
positive, it permits conclusive testing of family members.
Clinically, HHT most commonly involves the nasal
mucosa, skin, lungs, central nervous systemic, liver, and gastrointestinal tract [11, 12, 14, 16, 18–20, 22]. Spontaneous epi-
staxis eventually occurs in over 90% and is often ameliorated
with nasal moisturization and oral iron for blood loss. Epistaxis
can be severe requiring both iron infusions and blood transfusions. They may require care from an otolaryngologist familiar with HHT.While gastrointestinal telangiectases are found
in 55–70%, bleeding occurs in approximately 25%, generally
after 50years of age (except patients with JP-HHT). Denitive
management is challenging due to limited treatment options.
Central nervous system AVMs predominate in the brain and
occur in approximately 10%, more common in HHT type 1
[23]. The proper management of these is not certain, although
therapy may be appropriate for those larger than 1cm (refer to
Chap. 47 for more information on cerebral AVMs).
Key Point
Epistaxis is the most common presenting symptom of
HHT.
Liver AVMs are frequent, occurring in 41–85% on imaging
but symptomatic in only 5%, occurring more commonly in
HHT type 2. High-output heart failure is most common when
symptomatic. Biliary disease from ischemia related to shunting can cause biliary cysts, dilatation, and/or strictures, and
lab ndings of cholestasis (elevated bilirubin and alkaline
phosphatase). Symptoms include fatigue, right upper quadrant pain, jaundice, pruritus, and fever. Portal hypertension
from arterioportal shunting or nodular regenerative hyperplasia can result in gastrointestinal hemorrhage and ascites
(refer to Chaps. 27 and 42 for more information on GI bleeding and ascites, respectively). Less common manifestations
are portosystemic encephalopathy and mesenteric angina
from vascular steal. Therapy for symptomatic liver AVM is
primarily supportive, with medical management for uid
overload and cardiac effects. Embolization is not recommended due to a high complication rate [24]. Bevacizumab
may be benecial and liver transplant may be needed [25].
Pulmonary AVM occurs in 23–61% of patients with HHT,
more commonly in type 1 (46–76%) than type 2 (5–48%)
[14, 16–19, 22, 26]. One report on JP-HHT found an incidence for PAVM of 53% [27]. Pulmonary hypertension can
occur in HHT, but elevated pressures can also be due to a
large hepatic AVM.Overall, treatment of patients with HHT
requires a collaborative approach between many medical and
surgical specialists, typically at a dedicated HHT center.
Pathologically, PAVMs vary from microscopic and small
telangiectatic ones to large, thin-walled channels [28]. They
predominate in the lower lobes (65%), are multiple in twothirds (especially with HHT), and bilateral in 40% [1, 2, 4,
28, 29]. The majority (80–90%) have simple angioarchitec-
ture, with their arterial supply within one pulmonary segment, having one or perhaps a few subsegmental branches
supplying the arteriovenous connection and one or two
draining veins (Fig. 22.2a). Complex PAVMs comprise
10–20%, with several arteries derived from more than one
pulmonary segment (see Fig. 22.2b). Diffuse PAVM
Fig. 22.2 Young woman with HHT type 1, hypoxemia, and multiple PAVMs. (a) Simple left upper lobe PAVM, with a single feeding artery (black
arrow) and single draining vein (white arrow). (b) Complex right lower lobe medial segment PAVM whose primary supply is derived from this
segmental artery (white arrow) but also has two additional feeding arteries from the posterior segment (black arrows)
22 Pulmonary Angiography: Arteriovenous Malformation andPseudoaneurysm
249
Table 22.2 Clinical manifestations of pulmonary arteriovenous
malformation
Mechanism Consequences Manifestation Comment
Right-to-left
extracardiac
shunting
Rupture Hemorrhage Hemoptysis
Arterial
hypoxemia
Bland or
bacterial
paradoxical
embolism
Presumed loss
of pulmonary
capillary
metabolic
function
High-output
heart failure
Exertional
dyspnea
Fatigue
Cyanosis
Digital
clubbing
Polycythemia
Ischemic
stroke
Brain abscess
Other abscess
Migraine 16–46%
Hemothorax
Generally well
tolerated, with
minimal if any
symptoms even
with a large shunt.
HHT-related
bleeding
counteracts
polycythemia
11–55%
5–25%
4–8%
Rarely reported in
neonates with
extensive disease
3–18%
accounts for 5%, consisting of various-sized lesions extensively involving all subsegmental vessels of a pulmonary
segment or lobe, more commonly in the lower lobes [30–32].
Systemic arteries are rarely found to contribute or be the only
supply to a PAVM, with this more likely seen as acquired
collateral ow after pulmonary arterial embolization.
Clinical manifestations of PAVM are related to right-to-left
shunting or hemorrhage and will be present in more than
70% over time (Table22.2) [1–5, 8, 13, 29, 33, 34].
syndrome. Neoplasms can cause pseudoaneurysm through
erosion into a pulmonary artery. Traumatic pseudoaneurysms may be caused by injuries such as a penetrating wound
but also by iatrogenic causes such as a pulmonary artery catheter, prior surgery, and local ablation [37]. Less common etiologies are pulmonary embolism, traction bronchiectasis, and
pulmonary brosis, while in some, it is idiopathic. Pulmonary
hypertension appears to be a risk factor or exacerbating factor
for pseudoaneurysms similar to true aneurysms.
Key Point
Causes of pulmonary artery pseudoaneurysms:
• Chronic inammatory lung disease
• Infection
• Vasculitides
• Neoplasm
• Trauma
• Iatrogenic
• Idiopathic
Clinical manifestations from pseudoaneurysms are related
to rupture, local mass , local mass effect, or peripheral emboli
although they may be identied incidentally on imaging
[35, 36]. Symptoms include hemoptysis, which can be massive
and life-threatening, dyspnea, chest pain, cough, and bruit.
Key Point
Symptoms of pulmonary artery pseudoaneurysm:
Pulmonary Artery Pseudoaneurysm
Pulmonary artery pseudoaneurysms are acquired vascular
dilatations in which not all three layers of the vessel wall are
intact. Pulmonary artery pseudoaneurysms are rare, with a
combined prevalence with true aneurysms of less than 0.01%
[35, 36]. The most common cause is inammatory lung disease such as cystic brosis and sarcoidosis. Infections may
result in mycotic pseudoaneurysms through local necrosis of
a vessel wall and septic embolization from right- sided endocarditis to the vessel lumen or vasa vasorum (which can
result in multiple lesions). The classic Rasmussen’s aneurysm of tuberculosis is an example of local necrosis, but this
can also be caused by fungal and pyogenic organisms.
Primary vasculitides such as Behçet’s disease are another
type of inammatory process that can result in pulmonary
artery aneurysms that are actually pseudoaneurysms, as are
probably those of the poorly understood Hughes-Stovin
• Hemoptysis (can be life-threatening)
• Dyspnea
• Chest pain
• Cough
• Bruit
Clinical Indication
Pulmonary Arteriovenous Malformation
Even when silent, the capacity for PAVM to produce sudden,
life-threatening events such as stroke and brain abscess indicates a need for screening in those with HHT.Children appear
to be at lower risk for paradoxical embolization and hemorrhage unless they have more profound hypoxemia, indicating
larger and/or more extensive disease. Patients at even greater
risk of PAVM complications are pregnant women due to
250
J. S. Pollak
increased shunting, those with pulmonary hypertension, and
those with diffuse PAVM [13, 30–32, 38].
Screening is best accomplished with quantitative contrast
echocardiography. Intravenously injected microbubbles of
agitated saline are normally ltered by pulmonary capillaries
while PAVM will permit the delayed appearance of these in
the left cardiac chambers after three to ten heartbeats. A negative study nearly excludes PAVM.A grade 1 study of up to
30 bubbles on the left side on a single frame indicates that
CT would nd either no visible PAVMs or only tiny ones not
requiring embolization. Furthermore, a grade 1 study is not
indicative of PAVM as up to 28% of normal individuals without HHT may also be positive. Repeat screening in 5years is
appropriate to assess for possible PAVM enlargement. A
grade 2 study is 30–100 left-sided bubbles, and CT will show
PAVM in 45%, with 25% large enough to prompt embolotherapy. A grade 3 study is more than 100 left-sided bubbles
(Fig.22.3), and CT will show PAVM in 93%, with 77% large
Fig. 22.3 Screening echocardiogram with microbubbles of agitated
saline in a patient with HHT (grade 3) with bubbles appearing late in
left cardiac chambers on a four-chamber view. Bubbles show up as
bright echogenic foci on ultrasound
enough to prompt embolotherapy. Asymptomatic children
can be screened with pulse oximetry, looking for values in
the low nineties, with contrast echocardiography waiting
until mid-adolescence.
Key Point
Quantitative contrast echocardiography with agitated
saline is the best screening method for asymptomatic
PAVM in patients with HHT, reserving chest CT for
those with higher positive grades.
Direct imaging for PAVM is best accomplished with CT,
which should be done with thin slices and does not require
intravenous contrast given the high intrinsic conspicuity of
pulmonary vessels against aerated lung. CT is indicated after
grade 2 and grade 3 positive contrast echocardiograms or if
other manifestations are present to prompt directly going to
this study, such as a suspicious chest radiograph or unexplained hypoxemia. Typically, enlarged feeding and draining
vessels are seen connecting to a noncalcied, well- dened,
round, often lobular soft tissue lesion or serpiginous mass,
representing the arteriovenous connection or sac [39]
(Fig.22.4). A more poorly dened connection may also be
present, especially with complex and diffuse disease. In
addition to depicting the size, type, location, and number of
PAVMs, the diameter of the feeding artery or arteries should
be determined as this is a critical factor in deciding whether
to invasively treat. While magnetic resonance imaging or
magnetic resonance angiography holds promise for imaging
PAVM and also avoids ionizing radiation, most centers feel it
has not yet achieved a level of accuracy to replace CT [40].
Pulmonary angiography is rarely needed to diagnose equivocal lesions.
The indication for PAVM embolization is a feeding artery
greater than 2–3mm as this size appears to be where macroscopic paradoxical embolization becomes of greater risk and
Fig. 22.4 Three sequential
CT slices (a, b, c) depicting
the simple left upper lobe
PAVM shown in Fig.22.2a,
with its feeding artery (black
arrows) and draining vein
(white arrows)