Case report
Aortic intramural hematoma (IMH) represents 6.3% of all acute aortic
syndromes and most commonly involve the descending
aorta.1 It occurs predominantly in elderly males with
hypertension and is presumed to be caused by rupture of the vasa
vasorum, pathological neovascularization, or bleeding originated by
rupture of an ulcerated plaque.2 It usually presents
with abrupt chest or back pain and diagnosis is based on computed
tomography or transesophageal echocardiography.2
In contrast to the management of aortic dissection (AD), the standard
treatment for IMH and clinical course remains
unclear.3 As with AD, IMH is often categorized as
either Stanford type A or B. Conservative management is often the
strategy for type B IMH. However, much controversy exists for the
treatment of type A IMH, especially in patients with aspecific symptoms
such as with the case presented. Follow-up imaging studies and expedite
surgical repair in those who demonstrate hematoma expansion has been
suggested as the standard of care.4
A 58 year-old female with history of hypertension, dyslipidemia and
diabetes mellitus was referred to our emergency department following a
CT scan of the neck obtained for the workup of a parathyroid adenoma.
During review of the images an aortic intramural abnormal finding,
measuring 0.9 cm in thickness and with 73 Hounsfield density units
(consistent with the density of a hematoma: 40-90 HU), was incidentally
surrounding the ascending thoracic aorta. A small pericardial effusion
with identical radiologic density was associated with the findings. The
patient denied chest or back pain except for occasional self-resolving
discomfort in the left infrascapular region.
Six month follow-up chest CT angiography was consistent with an increase
in size of the hematoma (2.7 cm), now involving the ascending aorta and
the proximal aortic arch with a new focal protrusion at the level of the
main pulmonary artery with accompanying small-to-moderate
hemopericardium (Fig. 1A and B ). There was no evidence of
dissection or aneurysm, no concomitant severe coronary artery
calcification and the rest of the aorta and its branches were normal. A
transthoracic echocardiogram showed no valve abnormalities and a
well-preserved left ventricular function with an ejection fraction
estimated at 60%. In light of the progression of the hematoma and
extension into the main pulmonary artery, urgent surgical intervention
was recommended with plans for replacement of the involved ascending
aorta.
Upon entry into the pericardium, the expected hemopericardium turned out
to be a clear effusion. The ascending aorta had a leather-like aspect
with white dense fibrotic tissues surrounding the adventitia and a
thickened aortic wall extending into the arch (Fig. 2A and B ).
There were dense fibrous inflammatory adhesions between the medial
aspect of the ascending aorta and the pulmonary artery. Under
cardiopulmonary bypass and deep hypothermic circulatory arrest, the
distal ascending aorta was resected. The wall appeared to be severly
thickened with dense fibrotic tissue, and there was no evidence of
intimal entry tears, flaps or an intramural hematoma. The diseased
aortic segment was replaced with a 26 mm Dacron graft.
Pathology of the specimen revealed extensive lymphoplasmacytic
infiltrate in an expanded, markedly fibrotic adventitia consistent with
lymphoplasmacytic aortitis (Fig. 3A and B) . The lymphoid
infiltrate was found to be polymorphous, with a mild predominance of
B-cells (Fig. 3C ). Staining for Ig showed predominance of IgG
positive cells (Fig. 3D ) but only a few IgG4, ruling out IgG4
related disease. Further serologic assessment found no evidence of
auto-antibody-associated disease markers and treponemal serologies were
negative as well.
The management of intramural hematoma remains unclear, especially for
those who have an asymptomatic presentation or an incidental finding.
Hata M. et al3 reported a postoperative mortality of
5.4% for those with type A IMH complicated by cardiac tamponade, aortic
regurgitation, acute MI or organ malperfusion undergoing emergency
surgery, 0% for those with uncomplicated IMH who had emergency surgery
and 25.8% for those had conservative management. This significant
difference in mortality supports the aggressive treatment for type A IMH
with a rationale that uncomplicated patients are hemodynamically stable
prior to surgery, decreasing perioperative mortality
significantly.3
Unfortunately, as this case shows, oftentimes etiology cannot be
determined solely on imaging techniques despite the predictive accuracy
that radiologic features may have, and intra-operative findings may not
be consistent with disease presentation. When there is suspicion for
aortitis, positron emission tomography (PET) could potentially aid in
differentiating it from IMH.5 However, this patient
lacked symptoms of rheumatologic disease, inflammatory markers or other
features suggestive of lymphoplasmacytic aortitis that would warrant
such imaging at the time.
The presented case demonstrates the discrepancy between radiologic
features (expanding type A IMH) supporting surgical intervention, and
intraoperative and pathology findings that could have supported a
conservative management. It remains largely up to the surgeon’s
discretion to make a decision to operate in early stages or to monitor
progression to features that may warrant urgent care such as expanding
aneurysm, involvement of other structures, hemopericardium or risk of
dissection.