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Chapter 20 Inferior Vena Cava: Embryology and Anomalies 303
of the vena cava. Ramanathan et al. reported a single case of absent infrarenal
vena cava in a young female patient where peripartum records were available
and documented caval thrombosis extending into the right renal vein. They
suggest that this finding, as well as the fact that simple abnormal develop-
ment of the right supracardinal vein would not explain the failure of the right
postcardinal vein to persist, support the theory that this abnormality is not
developmental but acquired secondary to caval thrombosis.
40
Fig. 9 (continued) cava is absent at this level ( asterisk ) and venous drainage is via
retroperitoneal collaterals. ( c ) At this level, the retroperitoneal collateral venous drainage
forms a confluence and drains into the azygos vein (arrow). ( d ) Venous contrast from
the hepatic circulation can be seen emptying directly into the right atrium ( arrow 1 ). The
dilated azygos vein is again noted ( arrow 2 ). ( e ) Lower extremity venous return via the
azygos (minimally opacified) is seen here mixing in the superior vena cava ( arrow )
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304 B. Knipp et al.
The most common presentation is an asymptomatic finding on CT scanning;
the most common symptoms are due to deep venous thrombosis. Balzer et al.
reported a case of a patient presenting with a retroperitoneal mass and bleed-
ing who underwent laparotomy which demonstrated rupture of an aneurysmal
collateral vein in the setting of absence of the infrarenal cava. This was man-
aged via a PTFE interposition graft to reconstruct the cava, as well as bilateral
arteriovenous fistulae. The reconstruction was patent at 4 months.
37
Management of absence of the infrarenal inferior vena cava is similar in
principle to that for other caval anomalies. For the asymptomatic patient, risk
reduction is recommended. For patients with a history of venous thrombotic
or thromboembolic disease, long-term or lifelong anticoagulation is appropriate.
Surgical reconstruction may be attempted in life-threatening situations, as
above, or in cases of recalcitrant symptoms. Shah et al. reported a case of an
otherwise healthy 30-year-old male with a history of multiple deep venous
thrombi, chronic venous stasis, and ulceration who was managed conserva-
tively with aggressive compression therapy, exercise, anticoagulation, and a
venous pump.
41
Similarly, Dougherty et al. report a case of an otherwise healthy
41-year-old male who presented with recurrent venous stasis ulceration and
was discovered to have complete absence of the vena cava from the level of the
iliac bifurcation to the right atrium; outflow was via multiple lumbar collaterals
draining into an enlarged azygos system. This patient underwent PTFE bypass
grafting from the right iliac vein to the azygos vein and creation of an arteriov-
enous fistula. This reconstruction maintained patency up to 30 months.
42
Multiple Venous Anomalies
While the previously described anomalies of the vena cava can be problem-
atic interoperatively when present in isolation, they can also be found in a
variety of combinations. Occasionally, it is necessary to abort attempts at
Fig. 10 Chest x-ray from a patient with anomalous IVC with azygos continuation. Note
the right paratracheal structure ( arrow ) which is the dilated azygos vein. This anomaly
was discovered during a laparotomy for apparent paraganglionoma
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Chapter 20 Inferior Vena Cava: Embryology and Anomalies 305
an intra-abdominal surgical approach and pursue other options such as extra-
anatomic bypass or endovascular repair.
21
General Principles in the Management of Vena Caval Anomalies
The most frequent nonoperative complication of caval anomalies is deep venous
thrombosis of the iliac or femoral veins.
43
In a series of 97 consecutive patients
diagnosed with deep venous thrombosis, 5 of 31 patients with iliac vein involve-
ment were found to have abnormalities of the vena cava including absent renal
segment and absent postrenal segment to complete absence of the entire inferior
vena cava. Only one of the five patients had a hypercoagulable state identi-
fied. These patients tended to be younger than other patients in the series.
2,
38
Other studies have documented that approximately 5% of young patients with
deep venous thrombosis have an associated vena caval anomaly, and this rate
is higher when the thrombosis is bilateral.
34,
44
In a review of all case reports in
the literature through 2002 of patients with deep venous thrombosis and caval
anomalies, the mean age of this patient group was found to be 27 years. A total
of 54% of cases were bilateral, and 69% had no identifiable hypercoagulable
disorder.
45
These data suggest that young patients with no known risk factors for
hypercoagulable disorders who present with iliac vein thrombosis, especially if
bilateral, should be evaluated for caval anomalies.
While there are no large studies regarding the management of patients with
thrombotic disease in the setting of caval anomalies, the general consensus
in the limited literature on this topic seems to favor long-term (6 months to 2
years) or lifelong anticoagulation.
37–
39,
44–
48
Conservative measures including
stocking support, leg elevation, and exercise are also recommended.
48
A final word regarding preoperative radiology for aortic surgery. Due to the
prevalence of many of these venous anomalies in the general population, they
are often considered clinically insignificant normal variants by radiologists.
Clear communication between the surgeon and the radiologist regarding the
need to evaluate for venous anomalies may provide superior surgical planning
and decrease the rate of venous injury during aortic surgery.
References
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and renal veins: embryologic and surgical considerations . Urology . 1999 : 53 ; 873 – 80 .
6 . Gladstone RJ . Development of the inferior vena cava in light of recent research, with
especial reference to certain abnormalities, and current descriptions of the ascending
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7 . Anderson RC , Adams P , Burke B . Anomalous inferior vena cava with azygos con-
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306 B. Knipp et al.
8 . Macchi V , Parenti A , De Caro R . Pivotal role of the sub-supracardinal anastomosis in
the development and course of the left renal vein . Clinical Anatomy . 2003 : 16 ; 358 – 61 .
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American Journal of Anatomy . 1925 : 35 ; 331 – 83 .
10 . Karaman B , Koplay M , Ozturk E , Basekim CC , Ogul H , Mutlu H , Kizilkaya E ,
Kantarci M . Retroaortic left renal vein: multidetector computed tomography angi-
ography findings and its clinical importance . Acta Radiologica . 2007 : 48 ; 355 – 60 .
11 . Aljabri B , MacDonald PS , Satin R , Stein LS , Obrand DI , Steinmetz OK . Incidence
of major venous and renal anomalies relevant to aortoiliac surgery as demonstrated
by computed tomography . Annals of Vascular Surgery . 2001 : 15 ; 615 – 8 .
12 . Matano R , Gennaro M , Mohan C , Ascer E . Association of intra-abdominal
pathologies and vascular anomalies with infrarenal aortic aneurysm: a computed
tomographic study . Cardiovascular Surgery . 1993 : 1 ; 27 – 9 .
13 . Reed MD , Friedman AC , Nealy P . Anomalies of the left renal vein: analysis of 433
CT scans . Journal of Computer Assisted Tomography . 1982 : 6 ; 1124 – 6 .
14 . Alexander ES , Clark RA , Gross BH , Colley DP . CT of congenital anomalies of the
inferior vena cava . Computerized Radiology . 1982 : 6 ; 219 – 26 .
15 . Ueda J , Hara K , Kobayashi Y , Ohue S , Uchida H . Anomaly of the inferior vena
cava observed by CT . Computerized Radiology . 1983 : 7 ; 145 – 54 .
16 . Kukubo T , Oyama K , Ohtomo K , Yashiro N , Itai Y , Iio M , Masuyama S . CT of
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18 . Holden A , Smith A , Dukes P , Pilmore H , Yasutomi M . Assessment of 100 live
potential renal donors for laparoscopic nephrectomy with multi-detector row helical
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19 . Kawamoto S , Lawler LP , Fishman EK . Evaluation of the renal venous system on
late arterial and venous phase images with MDCT angiography in potential living
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20 . Lin CH , Steinberg AP , Ramani AP , Abreu SC , Desai MM , Kaouk J , Goldfarb DA ,
Gill IS . Laparoscopic live donor nephrectomy in the presence of circumaortic or
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aortic surgery: avoiding vascular injury . Journal of Vascular Surgery . 1987 : 6 ; 590 – 3 .
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tion to the type of posterior vena cava in man . American Journal of Anatomy .
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Chapter 20 Inferior Vena Cava: Embryology and Anomalies 307
30 . Brener BJ , Darling RC , Frederick PL , Linton RR . Major venous anomalies com-
plicating abdominal aortic surgery . Archives of Surgery . 1974 : 108 : 159 – 65 .
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collateral venous aneurysm in a patient with agenesis of the inferior vena cava: A
case report . Journal of Vascular Surgery . 2002 : 36 : 1053 – 7 .
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Lee Yong Won , Kim SK . Congenital absence of inferior vena cava as a rare cause
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Abstract A fistula between the inferior vena cava and aorta is a rare finding,
occurring in 0.2–1.3% of abdominal aortic aneurysms (AAA). The incidence
is 1% in asymptomatic and 3–4% in symptomatic aneurysms. Most fistulas
occur as a complication of AAA, but 5–10% can occur because of mycotic
aneurysms. Ehlers-Danlos and Marfan’s syndromes or Takayasu’s arteritis
can also cause fistulas. Rarely low-velocity penetrating trauma, such as a stab
wound, can result in an aortocaval fistula. However, the majority of penetrating
injuries to the aorta result in either death or hemodynamic instability necessi-
tating surgical exploration, such that a fistula does not have the opportunity to
form. Nevertheless, congestive heart failure in a young patient with a history of
trauma should alert the physician to a possible aortocaval fistula.
Keywords Aortocaval fi stula, Aortic Disease, Aortic Aneurysm, Congestive
Heart Failure
Presentation
The simultaneous presentation of abdominal aortic aneurysms (AAA) and con-
gestive heart failure (CHF) usually represents unrelated processes. Therefore,
the CHF should be treated prior to AAA repair. However, the persistence of
CHF despite treatment suggests a fistula or some other ominous finding.
Patients may complain of back or abdominal pain. On physical examination,
there may be a pulsatile abdominal mass, 75% will have an audible continuous
bruit and 25% a palpable thrill. In a study performed at the Mayo clinic, 94%
of patients with aortocaval fistulas were symptomatic at presentation, but only
17% had a triad of pain, pulsatile mass, and abdominal bruit.
1
CHF associated with aortocaval fistula is one of a hyperdynamic, high
output state. Therefore, patients may present with tachycardia, hypertension,
decreased diastolic blood pressure, cardiac dilation with an associated mur-
mur, jugular venous distension, hepatomegaly, swollen legs, or venous stasis
disease. There have also been reports of saphenous vein bruit.
2
Previously
undiagnosed congenital abnormalities such as patent foramen ovale, or central
malignancies, may contribute to circulatory overload and heart failure. Renal
Chapter 21
Aortocaval Fistula
Tamara N. Fitzgerald , Bart E. Muhs , and Alan Dardik
G. Upchurch and E. Criado (eds.) Aortic Aneurysms, Contemporary Cardiology
DOI: 10.1007/978-1-60327-204-9_21, © Humana Press, a part of
Springer Science + Business Media, LLC 2009
309
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310 T.N. Fitzgerald et al.
failure is often present. Rarely patients may present with lower gastrointestinal
bleeding in cases with visceral ischemia or hematuria if venous engorgement
of the bladder is present. Lower extremity claudication may also be present.
Diagnosis
The initial test to confirm the presence of an AAA is usually an ultrasound, but
this is not the best imaging option. Occasionally a fistula may be discovered
with color flow on the duplex ultrasound, but this is rare, and preoperative
planning is not routinely performed with ultrasound. In the past, aortocaval
fistulas were more often discovered unexpectedly in the operating room ,
during the course of open repair of an aneurysm.
Aortography is the gold standard for diagnosis, but now, more commonly,
computed tomography (CT) and magnetic resonance (MR) angiograms are
used to assess AAA and associated fistula. CT is more commonly used,
especially as patients routinely receive CT to determine endovascular repair
(EVAR) candidacy. This leads to increased preoperative detection of fistulas.
Early filling of the inferior vena cava (IVC) after intra-aortic contrast injection
is indicative of a fistula (Fig. 1 ). MR angiography can demonstrate this finding
as well, but is less commonly used.
Treatment
The natural history of an aortocaval fistula is progressive CHF leading to death.
Therefore, the fistula and associated AAA should be immediately repaired.
However, even with successful surgical repair, there is an associated 22–51%
mortality largely due to blood loss, cardiac decompensation, and pulmonary
embolus. Survival rates are generally higher for elective repairs and lower
for emergency repairs of ruptured AAA or elective repairs of AAA in which
the fistula was not preoperatively diagnosed. Today, with proper preoperative
angiographic study, it is increasingly rare for a fistula to go undiagnosed and
encountered unexpectedly during open aneurysm repair.
Fig. 1 Arterial phase computed tomography ( CT ) demonstrating an aortocaval fistula.
In addition to contrast in the aorta, contrast is also simultaneously present in the infe-
rior vena cava ( IVC )
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Chapter 21 Aortocaval Fistula 311
Preoperatively, all patients with suspected aortocaval fistula should receive a
transesophageal echocardiogram to evaluate cardiac performance and hemody-
namics as well as to demonstrate alternative sites of, or potential additional, fis-
tulas, including those due to a previously undiagnosed patent foramen ovale. The
central venous pressure is usually elevated and patients may have varying degrees
of renal failure. Therefore, in patients with severe symptoms requiring therapy, a
pulmonary artery catheter should be used to evaluate left-to-right shunt or high
output cardiac failure, and it can also be used to guide fluid management. In most
cases, renal function will return to normal after a successful repair.
The hemodynamic consequences of AAA-IVC fistula repair should be
anticipated intraoperatively. Both the cardiac output and the mixed venous
oxygen content should fall to normal values. Continued fall in cardiac output
to low values likely reflects low filling pressures that will be responsive to
fluids. Mild acidosis may be present after repair as well.
Operative Repair
Traditional open repair is performed either from the transperitoneal or from
the retroperitoneal approach, depending on aneurysm configuration and
surgeon preference. Although successful operation is expected with proper
preoperative diagnosis and planning, complications include bleeding, infec-
tion, hemodynamic instability, impotence, colon ischemia, cardiac failure,
prolonged ventilator dependence, stroke, air embolism, pulmonary embolism,
acute limb ischemia, and death.
Repair should proceed in standard fashion including dissection, vessel con-
trol, and heparinization. Acute fistulas are easily entered, whereas chronic fis-
tulas can be encased in fibrous tissue or an inflammatory mass. Chronic fistulas
may also have thinned, large arteries and bulging veins, adding to the difficulty
of vascular isolation. Patients must be adequately prepped so that major bleed-
ing can be controlled. For high abdominal fistulas, the chest should be prepped.
The fistula and IVC do not need to be isolated or dissected individually. After
aneurysm exclusion and opening of the sac, back bleeding from the fistula is
characteristically quite large. Sponge sticks may be used to compress the IVC
(Fig. 2 ). Venous control may also be achieved by intermittent clamping of the
artery, but Fogarty and Foley catheters may also be used. Control of the IVC
may diminish venous return to the heart, and should be performed cautiously.
Massive venous bleeding upon opening the aneurysm sac should alert the sur-
geon to an undiagnosed fistula, but can be generally easily controlled (Fig. 2 ).
Once control of the aorta has been achieved, repair of the fistula should
be performed from within the aneurysm sac. Care should be taken not to
manipulate the aneurysm as clot may be dislodged into the fistula and lead to
a pulmonary embolus. The vein should be repaired first, usually by primary
closure, but Teflon pledgets may be helpful. Next, the aortic aneurysm should
be repaired with a standard aortic graft.
Rarely, aortocaval fistula is a complication of aortitis. If the surgical field
is contaminated due to severe aortic infection, routine principles of vascular
surgery are followed and the septic tissue should be debrided. The fistula
is oversewn, the artery closed proximally and distally, and extra-anatomic
arterial bypass performed. Once the abdomen is closed, a subcutaneous bypass
can be placed in a clean surgical field to allow adequate perfusion of the legs.
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312 T.N. Fitzgerald et al.
Alternatively, a prosthetic graft can be placed into the contaminated field after
the aorta has been debrided and thoroughly irrigated with saline or antibiotic
solution. An antibiotic coated graft can be used, if available. Once the graft has
been placed, an omental pedicle should be used to cover the graft.
Endovascular Repair
As preoperative diagnosis of fistulas with CT becomes more common,
endovascular stent-graft repair becomes an important consideration. Given the
relatively high operative mortality and morbidity of open repair, the EVAR
option offers the potential benefits of decreased blood loss, virtually no chance
for air embolus, decreased hospital stay, and a more rapid return to normal
activities. Once anatomical suitability has been determined, typically by the
presence of adequate proximal and distal sealing zones, then EVAR may be an
acceptable approach for repair of an aneurysm with an IVC fistula.
The immediate efficacy of EVAR has been demonstrated in an animal model,
4
but as with all aortic stent grafts, careful follow-up must be maintained to evalu-
ate endoleaks.
5–
7
Endoleaks can cause fistulas to reoccur. However, isolated non-
aneurysmal aortocaval fistulas represent a different disease process than AAA.
The purpose of treatment in AAA is to prevent rupture, whereas in aortocaval
fistula, the primary measurement of success is restoration of normal physiology
Fig. 2 Technique for controlling bleeding from an aortocaval fistula and fistula repair
via an intra-aortic suture closure. From Dardik et al
3
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Chapter 21 Aortocaval Fistula 313
via the treatment of a large arteriovenous shunt. This has implications for follow-
up. Traditional follow-up of EVAR has included contrast CT on a yearly basis to
evaluate the presence of endoleak. This usually exposes patients to substantial
radiation and nephrotoxic contrast. In EVAR for AAA, the purpose of surveil-
lance is to eliminate any endoleak that presents a risk for rupture. Conversely,
in aortocaval fistulas, a small, hemodynamically insignificant endoleak likely
needs no treatment at all. It has been proposed that nonaneurysmal, aortocaval
fistula treated via EVAR can be followed adequately by yearly IVC duplex
scanning. If elevated arterial velocities are not encountered, then the radiation
and contrast of a CT can be eliminated. Abnormal duplex examinations should
prompt a contrast CT or MR angiogram for additional delineation.
There have been reports of aortocaval fistula treatment with coil emboliza-
tion, with coils placed into the midfistula tract.
8
This method is likely suitable
only for very small fistulas with long fistula tracks. Large, short fistulas are
high-flow phenomena. Endovascular coils placed in these high-flow commu-
nications carry a high risk of coil embolization to the lungs. Future endovas-
cular solutions may involve occlusion devices, similar to the Amplatzer septal
occluder or the Helix occluder device (W.L. Gore) used to treat intracardiac
septal defects with large shunts.
The endovascular treatment of aortocaval fistulas lacks long-term data to
evaluate the outcome of this treatment modality. Most case reports have only
1-year follow-up,
7,
9
and randomized, controlled trials or multicenter studies
are unlikely to ever occur given the rarity of this condition. Nevertheless,
endovascular options appear promising and deserve additional study.
Aortocaval fistula repair is associated with a 50% mortality. In the presence
of persistent renal failure, the results are dismal. Aortocaval fistulas should be
repaired as soon as possible after diagnosis in order to minimize end-organ dam-
age from sustained high cardiac output. EVAR is a new approach to repair an
aortocaval fistulas and the associated aortic aneurysm, and will be considered
more often as CT is used preoperatively to identify aortocaval fistulas. However,
long-term data must be obtained to determine the durability of this technique.
References
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