AJR 2001; 177:256-257
© American Roentgen Ray Society
Mycotic Pseudoaneurysm Presenting As a Pulsatile Mass at Sternotomy Incision
Peter R. Zeman and
Robert L. Nolan
Queen's University at Kingston Kingston, Ontario, K7L 2V7
Canada
Pseudoaneurysm formation at the graft anastomotic site after coronary
artery bypass surgery is rarely diagnosed in patients during life. A large
pseudoaneurysm presented as a pulsatile mass at the sternotomy incision.
A 46-year-old man had a sternotomy and quadruple saphenous vein bypass
procedure that was complicated by mediastinitis and sternal dehiscence.
Methicillin-resistant Staphylococcus aureus infection was treated
with sternal débridement and vancomycin. Two
months later, the patient presented with fever, malaise, and chest wall
tenderness associated with elevated WBC and erythrocyte sedimentation rate.
Coronary angiography revealed a 4-cm pseudoaneurysm at the anastomosis of the
right coronary artery vein graft and aorta. The pseudoaneurysm was repaired
with a patch (synthetic graft material). Methicillin-resistant S.
aureus was cultured. Post-operatively, the patient developed cerebral
edema, seizures, and coma. The sternotomy incision oozed dark blood and was
unstable. Five days later, there was a pulsatile mass at the sternotomy
incision. Unenhanced helical CT of the thorax showed a low-attenuation mass
extending from the aorta into the subcutaneous tissues
(Fig. 2A). Contrast-enhanced CT
findings confirmed the diagnosis of a pseudoaneurysm
(Fig. 2B). It ruptured
spontaneously shortly thereafter resulting in the patient's death.

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Fig. 2A. 46-year-old man with aortocoronary graft pseudoaneurysm.
Unenhanced CT scan shows low-attenuation mass (straight arrows)
extending from aorta through sternotomy incision into subcutaneous tissues
(curved arrow).
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Fig. 2B. 46-year-old man with aortocoronary graft pseudoaneurysm.
Contrast-enhanced CT scan shows enhancement that is consistent with
pseudoaneurysm and adjacent area of lower attenuation that is compatible with
hematoma (arrow).
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Patients with aortocoronary grafts may develop a true aneurysm caused by
atheromatous disease or a pseudoaneurysm caused by infection, faulty suture
technique, operative vein graft damage, or an intrinsic weakness of the graft
or proximal artery [1]. A
pseudoaneurysm is more common than a true aneurysm, usually occurs at the
graft anastomosis with the aorta, and is usually an early complication.
Rupture, thrombosis, graft occlusion, superior vena cava obstruction,
embolization, and fistula formation to the right ventricle may complicate
pseudoaneurysm [1]. It occurs
in 0.2% of all aortocoronary bypass procedures and is the cause of death in
approximately 3% of all late deaths
[2].
Mediastinitis complicates 0.4-5% of aortocoronary bypass procedures and is
responsible for at least 50% of the cases of pseudoaneurysm formation
[3]. The prevalence of
pseudoaneurysm formation in patients with Dacron (name of manufacturer of
Dacron, city, state/country) grafts is approximately 5.5%
[4].
The diagnosis of pseudoaneurysm requires a high clinical index of suspicion
because the patient may be asymptomatic or have nonspecific symptoms and
signs. Diagnosis is critical because pseudoaneurysm is a surgical emergency.
CT is a particularly valuable technique for the diagnosis of post-surgical
complications of sternotomy and aortocoronary bypass surgery. CT is
efficacious for the diagnosis of mediastinitis, sternal osteomyelitis and
dehiscence, hematoma, and pseudoaneurysm. Enhanced CT permits differentiation
between abscess, hematoma, and pseudoaneurysm.
References
-
Acosta AR, Valle DE, Calimano MT, Diethelm L. Aortic pseudoaneurysm
after coronary artery bypass AJR
1998;171:842
-843
-
Keon WJ, Bédard P, Akyurekli Y,
Brais M. Causes of death in aortocoronary bypass surgery. Ann
Thorac Surg 1977;23:357
-360[Abstract]
-
Smith JA, Goldstein J. Saphenous vein graft pseudoaneurysm
formation after postoperative mediastinitis. Ann Thorac
Surg 1992;54:766
-768[Abstract]
-
Gaylis H. Pathogenesis of anastomotic aneurysms.
Surgery
1981;90:509
-515[Medline]

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