The Superior Vena Cava: Conventional
By Benjamin
S ALREADY noted, anomalies of the SVC
are fairly common and are nicely demonstrated on CT. I have illustrated them here in
conventional frontal projection so that you can
suspect or recognize them from the plain films.
Figure 1 illustrates double SVC and Fig 2 shows
a left SVC entering the left coronary sinus. A left
SVC can be recognized on the plain PA teleroentgenogram as a subtle vertical interface
extending caudally from the left clavicle to the
heart overlapping or lying just lateral to the
aortic knob. This interface vanishes as it
approaches the clavicle because of its location in
the anterior mediastinum (the cervicothoracic
sign’).
Another variant of the SVC is idiopathic dilatation (Fig 3).2 The enlarged vessel may mimic a
A
(Ai Subtraction
Figl.
Two cases of double
SVC.
patient.
Venous
catheterization
of heart
via the right
and passes
retrograde
into the left SVC.
W Same
catheter
fills the left SVC and coronary
sinus.
Seminars in Roentgenology,
Vol XXIV,
No 2 (April),
1989:
Projections
Felsont
mediastinal mass and lead to additional studies
and even unnecessary surgery. In my own experi-
From the Department
of Radiology,
University
Hospital,
Cincinnati.
fDr Felson died Ott 22, 1988.
Address
reprint
requests
to Benjamin
F&on,
MD,
Department
of Radiology,
#742, University
Hospital,
Cincinnati, OH 45247.
0 I989 by W.B. Saunders Company.
0037-I
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bilateral
various
angiogram.
Note the interconnecting
v&n.
arm. The catheter
her entered
the coronary
sinus from the
patient
as (B). Contrast
injection
into the left innominate
pp 9 1-95
(6) Another
right atrium
vein via the
91
BENJAMIN
Fig 1.
Fig 2.
Left SVC en route
to the coronary
sinus.
Lateral
to the aortic
knob
(black
arrow).
The shadow
Venous
phase
of an angiocardiogram
shows
contrast
sinus and right atrium.
FELSON
(Cont’d).
(Al PA telaroentgenogram.
disappears
as it approachas
filling
of the anomalous
left
Noto the vartkal
intarfaca
the davii
IcMvicathwacic
cava and its entry
into the
(white
arrow)
sign’).
(81
dilated
coronary
SUPERIOR
VENA
CAVA:
CONVENTIONAL
PROJECTIONS
Fig 3.
Idiopathic
difatation
of the SVC
simulated.
The shadow,
which
disappears
injection
shows
the dilated
right SVC.
Fig 4.
Jugular
lymph
sac. This
rare
anomalous
vessel
lies at the junction
of
the thoracic
duct and left internal
jugular
vein.
(A) Plain
film. A soft tissue
mass
(arrow)
bulges
from the left supraclavioular region.
It was easily
compressible.
(B)
Brachial
venogrsm.
Retrograde
filling
of
the sac is shown
(arrow).
in a young
woman.
(A) Teleroantgenogram.
st the clavicle,
decreased
with
the
93
Valsalva
A right superior
msneuver.
mediaatfnal
(B) Contrast
mass is
medium
BENJAMIN
Fig 4.
ence it is encountered most often in teenage girls.
The bulging shadow clearly diminishes on the
Valsalva maneuver, but remember that a bona
fide mediastinal mass may occasionally shift
medially with this procedure. It is sometimes
necessary to perform CT with contrast enhancement to make the diagnosis. The prominent SVC
need not be dilated, but merely positioned more
to the right than normal.’
Table
1. Superior
Common
1. Aneurysm
2.
Vena
of aorta
latrogenic
uloatrial
Caval
or great
fag, pacemaker,
shunt)
3. Lymphadenopathy
Obstruction*
artery;
AV fistula
central
line catheter,
ventric-
fesp lymphoma)
4.
Mediastinal
tuberculosis,
fibrosis
or granuloma
ergotrates,
irradiation,
5.
Neoplasm
of lung,
(eg, goiter, superior
(eg, histoplasmosis,
idiopathic)
esophagus,
thyroid,
sulcus carcinoma,
or mediastinum
cystic hygroma,
thymoma)
Uncommon
1. Axillary
2. Behcet
vein
S
3. Congestive
4. Idiopathic
5. Mediastinal
6.
Mediastinitis,
thrombosis
heart
with
failure
emphysema,
11.
12.
13.
14.
severe:
tension
pneumothorax
acute
7. Myxoma
of right atrium
8. Osteomyelitis
of clavicle
9. Pericarditis.
constrictive
10. Pneumoconiosis
(coalworkers,
erate mass
Postoperative
Sarcoidosis
extension
(eg, cogenital
silicosis)
heart
with
conglom-
disease)
Thrombosis
(eg, polycythemia
Vera)
Trauma (eg, laceration,
transection,
mediastinal
tome)
hema-
FELSON
(Cont’d).
Another congenital aberration you should be
aware of, not of the SVC but rather of the
innominate venous system, is the jugular lymph
sac. This rare anomaly occurs at the junction of
the internal jugular vein and subclavian vein, at
the site of entry of the thoracic duct.
Its derivation is interesting. The lymphatic
vessels embryologically
stem from the venous
system. Well-formed lymphatic valves prevent
reflux of blood into the lymphatics. The only
major connection between the two systems
retained at birth is the site of entry of the
thoracic duct adjacent to the origin of the innominate vein. With incompetence or absence of
valves at this site, the connection may be wideopen and dilated.
This is called the jugular lymph sac and may
be apparent clinically. It is usually found in the
left supraclavicular fossa but may be present on
the right side instead. It enlarges on Valsalva
maneuver. The diagnosis is readily confirmed by
either angiography or lymphography (Fig 4).4*5
Jugular lymph sac is usually mistaken for a
venous aneurysm and surgically removed, an
unnecessary intrusion.6’7
As stated elsewhere in this Seminar, SVC
obstruction has many causes. Table 1 is a Gamut
listing them.8 I have been surprised at how often
patients with complete SVC obstruction show no
clinical evidence of the condition. Even with head
lowered, the dilated veins and other signs of
superior caval obstruction may be lacking. The
reason I can make this statement so emphatically
is that for many years whenever I have noted a
SUPERIOR
VENA
CAVA:
Fig 6.
WC obstruction
the accessory
hemiazygos
brad&l
venogrem
shows
is notching
the right fdth
CONVENTIONAL
PROJECTIONS
with rib notching.
(A) The left eighth
rib is ckarty
notched
(verticalarrow).
v&n (the superior
intercostal
vein) juts out from
the aodc
knob
Omrii
obstruction
of the SVC (arrow)
with extensive
collaterals.
including
a tortuous
rib. Autopsy
showed
fibrocalcific
medisstinitis
obstructing
the superior
cava.
right superior mediastinal or RUL mass I begin
my study with a barium swallow, seeking evidence of downhill varices. I have demonstrated
them in about half the cases of SVC obstruction.
If the varices involve the upper esophagus, I
An enlarge4
arrow).
intercostal
brench
of
ISI Right
vein that
insist on venous angiography, which to date has
never failed to demonstrate the SVC obstruction.’ Rib notching from intercostal venous collaterals, though rare, is also an indication of SVC
obstruction (Fig 5).’
REFERENCES
1. Felson B: Chest roentgenology. Philadelphia: Saunders,
1973
2. Bell MJ, Gutierrez JR, Dubois JJ: Aneurysm of the
superior vena cava. Radiology 1970;95:3 17-8
3. Drasin E, Sayre RW, Castellino RA: Non-dilated
superior vena cava presenting as a superior mediastinal mass.
J Can Assoc Radio1 1972;23:273-4
4. Steinberg I, Watson RC: Lymphangiographic and
angiographic diagnosis of persistent jugular lymph sac. New
Engl JMed 1966;275:1471-4
5. Gordon DH, Rose JS, Kottmeier P, et al: Jugular
venous ectasia in children. Rudiotogy 1976;118: 147-9
6. Koh SJ, Brown RE, Hollabaugh RS: Venous aneurysm.
South Med J 1984;77:1327-8
7. Tatezawa T, Shiozawa Z, Akisada M, et al: Venous
angioma of the neck in a child. Pediotr Rndiol 1979;8:122-3
8. Felson B, Reeder MM: Gamuts in radiology (ed 2).
Cincinnati: Audiovisual Radiology of Cincinnati, 1987