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| Journal of the New Zealand Medical Association,
28-January-2005, Vol 118 No 1208
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Infective endocarditis with abdominal pain: just a
coincidence?
Calvin Ng, Ahmed Arifi, Song Wan, James Lau, Anthony
Yim
Mycotic aneurysm of the superior mesenteric artery is
uncommon and can be associated with significant morbidity and mortality. We
report a case of infective endocarditis with abdominal pain associated with
enlarging mycotic superior mesenteric artery aneurysm. With the non-specific
abdominal symptoms that are associated with superior mesenteric artery
aneurysms, clinicians should have a low threshold for appropriate abdominal
imaging in infective endocarditis.
Case reportA 23-year-old male was admitted with
a 4-week history of intermittent fever and malaise following an episode of right
foot cellulitis. At admission, his temperature was
38.5oC; pulse rate 100 and normotensive.
Examination revealed grade 5 ejection systolic murmur and grade 4 end diastolic
murmur at the left sternal border. Abdominal, pulmonary and neurological
examinations were unremarkable.
The C-reactive protein was 143 mg/L, white cell count 10.1 x
109/L, haemoglobin concentration of 10.6
mmol/L, and erythrocyte sedimentation rate of 53 mm/h. Echocardiogram revealed
thickened bicuspid aortic valves with vegetation associated with severe aortic
regurgitation. Blood cultures grew alpha-haemolytic
Streptococcus, and high dose penicillin
G and gentamicin was commenced with fever settling after 5 days.
Aortic valve replacement surgery was planned—however,
the evening prior to surgery, the patient developed several episodes of
diarrhoea with mild colicky abdominal pain that was exacerbated by oral feeding.
There was mild central abdominal tenderness, no mass was palpable, and no
distension or signs of peritonitis. Active bowel sounds were heard. Per rectal
examination and sigmoidoscopy were normal. The patient developed a low-grade
fever with white cell count of 9.0 x 109/L and
haemoglobin concentration 10.2 mmol/L—but his renal function, liver
function, amylase, and arterial blood gas were normal.
Stool microscopy and
Clostridium difficile toxin were
negative, and erect chest and abdominal radiographs were unremarkable. Computed
tomography with double-contrast revealed a 1.7 x 1.5 cm aneurysm at the
mid-to-distal part of the superior mesenteric artery (SMA). No extravasation,
mural thrombus, or dissection was seen. Selective arteriogram confirmed a 2.5 cm
fusiform SMA aneurysm arising proximal to origin of ileal branches, with good
perfusion to the small bowel. (Figure 1)
Figure 1. Selective arteriogram showing superior
mesenteric artery aneurysm
 Combined procedure was performed including aortic valve
replacement and mycotic SMA aneurysm resection and repair with saphenous vein
graft. No small bowel infarction was identified during surgery.
The patient returned to full diet on postoperative day 3,
and made an uneventful recovery. The aortic vegetation and SMA tissue showed no
growth after prolonged incubation. He was discharged after completing 4
weeks’ of postoperative intravenous penicillin G and gentamicin. The
patient remains well at follow-up 9-months post-operatively with no abdominal
complaints.
DiscussionMycotic aneurysms of the visceral
arteries are life-threatening diseases with potential to rupture and organ
ischaemia. The incidence of mycotic aneurysms associated with endocarditis is
between 2.5% and 10%.1
Mycotic aneurysms may form from direct bacterial invasion,
embolic occlusion, and immune complex deposition within the blood
vessel.2 The more common sites for mycotic
aneurysms include aorta and cerebral arteries.2
Intra-abdominal mycotic aneurysms such as SMA aneurysm can be relatively
asymptomatic particularly at the early stages.
Our patient presented with mild colicky abdominal pain
exacerbated by oral intake (claudication abdominis) and several episodes of
diarrhoea, which initially was diagnosed to be gastroenteritis or
Clostridium difficile colitis. Although
no evidence of small bowel infarction was found intra-operatively, acute
intestinal inflammation as well as mild ischaemia of the small bowel may both be
involved in inducing such symptoms. Non-specific abdominal symptoms and signs
may be confused with other less life threatening abdominal conditions and
clinicians should have a high index of suspicion.
Up to 38% of patients with superior mesenteric artery
aneurysm would have ruptured at presentation.3
Excluding differential diagnoses with stool microscopy and culture, and
Clostridium difficile toxin assay
should not delay definitive imaging with computed tomography (CT) of the abdomen
because aneurysm rupture or leakage is an emergency and carries significant
increase in morbidity and mortality.3,4
Selective visceral artery angiography following CT scan is
advocated by many surgeons to help guide surgery— however, it is
increasingly being replaced by contrast-enhanced magnetic resonance angiography
(MRA).5 In this case, the time course suggested
that the right foot cellulitis might have contributed to the development of
infective endocarditis, particularly in the presence of a congenital bicuspid
aortic valve. It is also interesting to note the speed at which mycotic SMA
aneurysms can rapidly enlarge from the time of CT scanning to performing
selective angiography. Classical management of mycotic superior mesenteric
artery aneurysm include surgical resection of the aneurysm (aneurysmectomy) and
arterial reconstruction with graft, or endoaneurysmorraphy with vein, followed
by further 4 to 6 weeks of antibiotics guided by culture sensitivity.
In ruptured aneurysms, emergency surgical repair or
embolisation of the ruptured aneurysm with metallic coils has been reported with
success.4,6 However, the operative mortality
associated with ruptured aneurysms can be 37% compared with minimal mortality
rate in elective repair.3
More recently with advances in stent technology,
endovascular stent-graft placement can be an attractive alternative to surgery,
particularly in patients who are non-fit for surgery, or for dissecting and
pseudoaneurysms of the SMA.7,8 Nevertheless,
early elective surgery should be considered for patients at good operative risk
with mycotic SMA aneurysm.
The case is a reminder that clinicians should have a high
index of suspicion and have a low threshold for appropriate abdominal imaging in
patients with infective endocarditis presenting with abdominal pain.
Author information:
Calvin S H Ng, Ahmed A Arifi, Song Wan, James W Y Lau, Anthony P C Yim, Section
of Cardiac Surgery, Division of Cardiothoracic Surgery, The Chinese University
of Hong Kong, Prince of Wales Hospital, Sha Tin, New Territories, Hong
Kong
Correspondence:
Professor Ahmed A Arifi, Head, Section of Cardiac Surgery, Division of
Cardiothoracic Surgery, The Chinese University of Hong Kong, Prince of Wales
Hospital, Sha Tin, NT, Hong Kong. Fax: (852) 2637 7974; email: Arifiahmed@hotmail.com
References:
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