CASE 11959 Published on 18.09.2014

Abdominal aortic aneurysm with fistula to inferior vena cava

Section

Cardiovascular

Case Type

Clinical Cases

Authors

Claudia Lorena Martínez Higueros MSc., Javier Pereda Rodríguez, Cristina Fernandez Rey.

Complejo Hospitalario de Segovia.
Radiology;
Calle Del Romero 4 1ºB
Segovia 40002;
Email:mahicl@gmail.com

Patient

58 years, male

Categories

Area of Interest Abdomen ; Imaging Technique CT-Angiography

Procedure Diagnostic procedure, Surgery ; Special Focus Arteriosclerosis, Aneurysms, Prostheses ;

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Clinical History

A 58-year-old man was admitted to the Emergency Room, complaining of diffuse abdominal pain. It became worst during the last 2 hours and was accompanied by dizziness, sweat and faint.
The physical examination showed low arterial blood pressure levels and signs of central abdominal tenderness with peritoneal irritation.

Imaging Findings

The abdominal X-ray showed no pathological finding and a CT angiography was performed to rule out acute mesenteric ischaemia.
The images revealed an abdominal aortic aneurysm (8 cm x 3 cm x 5 cm) immediately proximal to the iliac bifurcation. The wall thrombus showed heterogeneous attenuation signs, in keeping with intramural bleeding.
Interestingly, an early vivid enhancement was present in the inferior cava vein, reaching the same attenuation levels as the aorta. As opposed to this, a delay occurred in kidney and common femoral veins enhancement.
The patient underwent urgent vascular intervention where the abdominal aortic aneurysm with aortocaval fistula was confirmed.

Discussion

The abdominal aortic aneurysm falls within the aortic syndromes, where imaging plays an important role, not only in the diagnosis but for the surgical treatment and follow-up.
The clinical signs are not specific of this pathology and include: thoracic pain, abdominal pain irradiating to the back, disturbed vital signs, vasovagal symptoms, abdominal mass with murmur and cardiac overload signs, among others.

The radiological findings of impending rupture include: rapid growth of the aneurysm size, hyperattenuated crescent within the mural thrombus, thrombus fissure, draped aorta and stranding of the surrounding fat. Signs of complete rupture are: contrast material extravasation, retro or intraperitoneal haematoma. [2, 6]
The aortocaval fistula is a rare entity (<5%) associated with high mortality rates. It is considered a sign of complete rupture. [4, 5, 9]
Loss of fat planes between aorta and inferior cava vein, simultaneous enhancement of both vessels as well as kidney and femoral veins delay can be seen in the images.

Endovascular repair is nowadays the most common approach to these cases and has greatly contributed to reduce the post-surgical mortality rates. [4]
The technique includes the placement of an endovascular prosthesis bifurcated into one or both iliac arteries. [4]
In the cases with monoiliac prosthesis a femoral bypass is done and a caval filter is placed to avoid systemic embolisms, such as pulmonary embolism. [7, 3]
Additionally, in this case, embolization material was used (coils) for the closure of the aortocaval fistula with excellent results.

The CT angiography remains the imaging technique that offers the greatest advantages not only for the diagnosis but for the treatment control. Furthermore, other studies have promoted other techniques such as CEUS and MRI angiography with good results for cases where CT is not feasible. [10, 8, 11]

Teaching points:
Signs of impending rupture of the aneurysm include: change in the size, hyper-attenuated crescent, thrombus fissure, draped aorta, and stranding of surrounding fat planes.

Signs of complete rupture include: contrast extravasation, retro or intraperitoneal haematoma and aortocaval or aortoenteric fistula.

Imaging is the key tool for the diagnosis, management planning and follow-up.

The most useful imaging techniques are CT angiography, contrast enhancement ultrasound and MRI angiography. [1]

Differential Diagnosis List

Ruptured abdominal aortic aneurysm with aortocaval fistula.

Abdominal aortic aneurism and cardiac congestion

AAA with renal artery thrombosis

Final Diagnosis

Ruptured abdominal aortic aneurysm with aortocaval fistula.

References

[1] Donald M, et.al. (2014) Surveillance after endovascular abdominal aortic aneurysm repair. Cardiovascular Interventionist Radiology. Cadiovasc Intervent Radiol 37(4):875-88 (PMID: 24873921)

[2] Vu KN, et.al. (2014) Rupture signs on computed tomography, treatment and outcome of abdominal aortic aneurysms. Insights Imaging 5: 281-293 (PMID: 24789068)

[3] Guttikonda S, Vitellas Kenneth (2002) Ureteral leak after an abdominal aneurysm repair: case report. Emergency Radiology 9: 103-105 (PMID: 15290588)

[4] Takazawa A, Sakahashi H, Toyoma A (2001) Surgical Repair of a Concealed Aortocaval Fistula Associated an Abdominal Aortic Aneurysm: Report of Two Cases. Sur today 31: 842-844 (PMID: 11686570)

[5] Coulier B, Tilquin O, Etienne PY (2004) Multidetector row CT diagnosis of aortocaval fistula complicating aortic aneurysm: a case report. Emergency Radiology 11: 100-103 (PMID: 15517454)

[6] Kauffmann C et. Al. (2012) Measurements and detection of abdominal aortic aneurysm growth: accuracy and reproducibility of a segmentation software. European Journal of Radiology 1688-1694 (PMID: 21601403)

[7] Fossaceca R, et.al (2013) Endovascular Treatment of Ruptured Abdominal Aortica Aneurysm with Aortocava Fistula. Cardiovasc Intervent Radiol Nov 15 (PMID: 24232039)

[8] Bashir MR, Ferral H, Jacobs C, McCarthy W, Goldin M (2009) Endoleaks after endovascular abdominal aortic aneurysm repair: management strategies according to CT findings. AJR 192: W178-W186 (PMID: 19304678)

[9] Schwartz SA, Taljanovic MS, Smyth S O’Brien MJ, Rogers LF (2007) CT findings of rupture impending rupture, and contained rupture of abdominal aortic aneurysms. AJR 188 (PMID: 17179328)

[10] Clevert DA, et.al (2007) Contrast-Enhanced Ultrasound in detection and follow-up of infrarenal abdominal aortic aneurysm with aorto-caval fistula and endovascular treatment. Cardiovasc Intervent Radiol 30: 480-484 (PMID: 17205366)

[11] Gaa J, Böhm C, Tichter A, Trede M, Georgi M (1999) Aortocaval fistula complicating abdominal aortic aneurysm: diagnosis with gadolinium-enhanced three-dimensional MR angiography. Eur. Radiol 9:1438 - 1440 (PMID: 10460392)

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