(Circulation. 1997;96:288-294.)
© 1997 American Heart Association, Inc.
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From the cardiology departments of Hôpital Beaujon (T.L.), Clichy, Hôpital du Haut-Lévèque (R.R.), Pessac, and Hôpital Bichat (P.G.S.), Paris; and the Cardiovascular Surgery Department of Hôpital Saint-Joseph (C.L.), Paris, France.
| Abstract |
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Methods and Results Transesophageal echocardiography files collected between 1991 and 1995 in French academic cardiology centers were reviewed to identify patients who fulfilled the following criteria: (1) an arterial embolic event in the preceding weeks; (2) a mobile pedunculated aortic arch thrombosis, defined as an echogenic mass protruding into the lumen of the aorta and inserted on the aortic arch; and (3) absence of obvious diffuse aortic atherosclerosis or of aortic debris on transesophageal echocardiography. Twenty-three cases were identified from 27 855 examinations. Thromboses were located on the horizontal aorta (n=4), near the ostium of the left subclavian artery (n=5), or on the concavity of the posterior segment of the aortic arch (in the isthmus) (n=14). The insertion site was a small atherosclerotic plaque in 21 patients. The remaining aortic wall always appeared normal or mildly atherosclerotic. The mean age of the patients was 45±8.4 years (range, 26 to 61 years). All patients were treated with intravenous heparin after the diagnosis of aortic arch thrombosis, and surgical removal of the thrombosis was performed in 10 patients in whom histological examination confirmed an atherosclerotic process at the site of insertion of the thrombosis. The prognosis was mainly influenced by embolic events.
Conclusions Thromboses of the aortic arch appear to be a variant form of aortic atherosclerotic disease associated with arterial embolism in young patients.
Key Words: echocardiography aortic arch syndromes thrombosis embolism
| Introduction |
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We describe a series of young patients with unexplained arterial embolism in whom TEE revealed mobile pedunculated AATs without clear diffuse, atherosclerotic lesions.
| Methods |
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4 mm are a possible
source of cerebral emboli owing to their association with
ischemic stroke,9 such patients were excluded from
the study. Finally, aortic aneurysms were excluded. All TEE videotapes corresponding to patients who fulfilled these criteria were reviewed in consensus by two experienced echocardiographers from the core laboratory, and the clinical and biological characteristics and follow-up data on the patients were retrieved from the hospital files.
| Results |
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1
but <4 mm) with increased mural echo density. In 7 patients, the
insertion site was a more irregular and complex plaque (Fig 3
30% in
diameter.
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Patients
The clinical characteristics of the 23 patients are summarized in
Table 1
. There were 13 men and 10
women, with a mean age of 45±8.4 years (range, 26 to 61 years). All
but 3 patients had one or more cardiovascular risk
factors: smoking in 16, hypercholesterolemia in
11 (mean plasma cholesterol, 6.1±1.8 mmol/L),
hypertension in 6, and diabetes mellitus in 3. Assays for antithrombin
III, proteins C and S, fibrinogen, and antiphospholipid antibodies had
been performed in all patients, but only 4 (17%) had evidence of a
hemostatic disorder (protein C deficiency in 2 and antiphospholipid
antibody syndrome in 2). Fibrinogen levels were >4 g/L in 10 patients
(mean, 4.5±1.5 g/L). The initial arterial embolic event
was ischemic stroke in 5 patients, embolism in the arms in 10
(right superior limb in 3), embolism in the legs in 11, and visceral
artery embolism in 4. Ten patients had multiple emboli affecting more
than one territory. In most of the patients (19 [83%] of 23),
clinical onset of the embolic event was sudden. However, in 2 patients,
the initial manifestation was subacute limb ischemia
(evolving over 3 months), and in 2 patients the initial symptoms were
limited to dysesthesia of one hand.
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Treatment
Management of the embolic events included intravenous
heparin in all cases. However, in 4 patients, embolic events recurred
despite intravenous heparin. Peripheral
embolectomy was performed in 13 patients. One patient underwent
small-bowel resection for mesenteric ischemia.
Surgical ablation of the aortic mass was performed in 10 patients
an average of 6.8±3.6 days (range, 0 to 12 days) after discovery. The
decision to operate was based on the persistence of the mass on a
repeat TEE (n=4) or the highly mobile appearance of the thrombosis
(n=6, 2 of whom had evidence of recurrent embolism). In all cases,
surgery showed a mobile thrombosis inserted on the aortic wall (Fig 4
). Histological examination of the
surgical sample always confirmed a fibrinocruoric thrombus inserted on
an atherosclerotic plaque (Fig 5
). The site of insertion
showed atherosclerosis in all 10 patients, of whom 5
had calcifications and 3 had ulcerations (Table 2
). This
insertion site was located at the distal part of the aortic arch in the
region of the ligamentum arteriosum (n=6), 1 cm above this region
(n=1), around the ostium of the left subclavian artery (n=2), or facing
the origin of the left carotid artery (n=1). The surgical appearance of
the rest of the aortic wall was judged normal or mildly
atherosclerotic. In all but 3 patients, these findings correlated well
with TEE findings, both regarding the site of the thrombosis and the
macroscopic appearance of the insertion site (Table 2
). The surgical
procedure consisted of thrombectomy in all the patients, associated
with resection of atherosclerotic plaque in 5, of whom 3 underwent
combined repair of the aortic wall (using either a patch of
polytetrafluoroethylene [n=2] or a
prosthetic tube [n=1]). All the patients survived. The
complications of surgery were one axillo-femoral bypass infection and
one deep venous thrombosis of the lower limb. Six patients were
discharged from the hospital with warfarin therapy and the remaining 4
patients with aspirin therapy.
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In 13 patients, there was no surgical removal of the AAT, which was exclusively treated with anticoagulant therapy (intravenous heparin followed by warfarin). One patient died 24 hours after initial TEE, despite emergency laparotomy, of massive mesenteric infarction due to embolism in the superior and inferior mesenteric arteries. Postmortem examination confirmed the existence of a thrombosis located on an atherosclerotic plaque in the isthmic portion of the aortic arch, while the remainder of the aortic wall appeared normal. In the remaining 12 patients, a repeat TEE performed 3 days to 6 months after the first showed disappearance of the thrombosis in 11 patients. In the last patient, the TEE appearance was unchanged 2 years later, and the patient had no evidence of subsequent embolism.
Altogether, the cruoric nature of the mass on TEE was formally confirmed in 18 (78%) of 23 patients by surgical (n=10) or autopsy (n=1) examination of the thrombosis itself (in 6 of these 11 patients, it was further confirmed by direct analysis of the thrombus retrieved by embolectomy) or by surgical embolectomy (n=7). In the remaining 5 patients, the cruoric nature of the embolus or mass was not formally proven, but the echocardiographic appearance of the mass was highly suggestive of a thrombus.
Follow-up
All surviving patients (n=22) were discharged with either warfarin
(n=18) or aspirin (n=4) therapy and were followed up for an average of
18±14 months (range, 3 to 48 months). In 1 patient receiving aspirin
therapy, embolism recurred 11 months after thrombectomy. TEE
examination revealed recurrent thrombosis at the same site on the
aortic arch. Repeat thrombectomy was performed, associated with
resection of the atherosclerotic site of insertion and patch repair. No
symptomatic embolic events occurred in the remaining
patient. Sequelae were observed in 11 patients (50%) in the form of
neurological deficits (6 patients), lower-limb amputation (2), or
intermittent claudication (3). Eleven patients (50%) remained
asymptomatic.
| Discussion |
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Aortic arch is now recognized as a source of systemic embolisms that
complicate atherosclerotic plaques.9 11 19 The high
prevalence of insertion of thrombi on the wall opposite the ostia of
the aortic arch is striking. There was no obvious morphological feature
visible on echocardiography that would explain why
the majority of thromboses were attached to this area. This may be
related to the fact that areas of low wall shear stress (such as this
area) are predisposed to the development of atherosclerotic plaques,
which, even when minute, are likely sites for attachment of thrombi.
Several studies have demonstrated the impact of flow-velocity profiles
and wall shear stress on plaque localization.20 21 22
Amarenco and colleagues9 found mobile components on
complex aortic plaques, but these cases were infrequent (7 of 250
patients) and occurred on severe plaques (with a thickness
4
mm). Furthermore, although aortic atherosclerosis may
be complicated by thrombosis of ulcerated plaques, it usually occurs in
elderly patients.13 16 In their anatomic series, Amarenco
and colleagues23 did not find any ulcerated plaque on the
aortic arch of stroke patients aged <60 years. In previous large
studies of atherosclerotic plaques or debris, the average age was
always >70 years.5 8 11 19 23 24 In contrast, AAT can
affect younger patients: in the present study, the oldest patient
was 61 years old, and the mean age was 45. In contrast to aortic
debris, atheromas or calcified plaques were limited to the
thrombus insertion site on the aortic wall. The remaining aortic wall
was otherwise either normal or mildly atherosclerotic on TEE (in fact,
its thickness never exceeded 2 mm). Furthermore, in elderly
patients with embolic events and diffuse aortic
atherosclerosis, the distinction between thromboembolic
occlusion of a major artery, thromboembolic microembolization, and
atheromatous microembolization is frequently difficult
to perceive. In the AAT cases described here, we found evidence of the
cruoric nature of the embolism. The mobile mass observed on TEE in the
aortic lumen was indeed a clot. Its cruoric nature was proven by
surgical retrieval (of the embolus and/or the mass) or by autopsy in
78% of cases; in the remainder, TEE images were highly evocative. Both
the clinical and the echocardiographic appearances of
AAT differed from those of aortic dissection with thrombosis of the
false lumen, dissecting flaps,25 26 traumatic aortic
disruption,27 28 intramural
hemorrhages,29 30 or other rare causes of aortic
masses.
Although AAT appears morphologically distinct from "classic" aortic arch debris, the insertion site always appeared to involve an atheromatous plaque, and this was confirmed by postoperative pathological examination of the aortic wall in seven patients and by autopsy in one patient, in whom the aortic insertion site always showed typical features of atherosclerosis. AAT therefore appears to be a complication of atherosclerosis. Aortic atherosclerosis may constitute a spectrum of disease ranging from pure atherosclerotic debris floating in the aorta (most prevalent in elderly patients) to nearly pure clot formations (often found in younger patients). Considering the high thrombogenic potential of atherosclerotic plaques,31 it is extremely likely that these clots are inserted on atherosclerotic plaques, even when they are not visible on echocardiography. It is likely that many patients in fact have aortic atherosclerosis complicated by clot formation. We point out, however, that the population in our study (whose inclusion criteria did not include age per se) were young patients who did have extensive clot formations floating in the aorta, without TEE evidence of profuse atherosclerosis but with a history of embolic events. Therefore, this does represent a specific variant of aortic atherosclerosis with high embolic potential, different in its presentation from that previously described by other groups in older patients, even though the pathophysiology may be common.
TEE was particularly effective for identifying AAT and provided important additional information such as size and mobility, insertion site, and the appearance of the remaining aortic wall. There was a good concordance between TEE and surgical or pathological findings regarding AAT location, insertion site, and appearance of the aortic wall.
Although the optimal treatment of AAT remains to be defined, anticoagulant therapy appears to be a logical component of medical therapy. However, recurrent embolic events may occur despite anticoagulant therapy in patients who do not undergo surgical removal of the AAT. In this series, embolism recurred in 4 (27%) of the 15 patients who had not originally undergone surgical removal of AAT, despite heparin therapy. In our experience, despite its own risk, surgical removal of both the thrombosis and the plaque does not appear to be associated with the high risk of surgical removal of aortic debris.32 Other therapeutic modalities include thrombolysis18 and balloon embolectomy.16
These therapeutic options emphasize the importance of identifying AAT and distinguishing it from aortic debris. It must be stressed that in our series, the prognosis appeared to be mainly related to the sequela of the embolic events: 1 patient died and 11 others had important sequelae, such as amputation or neurological deficits.
In conclusion, thromboses of the aortic arch appear to be a variant form of aortic atherosclerotic disease associated with arterial embolism in young patients. In these patients with unexplained systemic embolism, AAT is to be included among potential causes and can be identified by TEE.
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| Acknowledgments |
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| Footnotes |
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1 A complete list of the study investigators may be found in the "Appendix." ![]()
| Appendix 1 |
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Received November 14, 1996; revision received January 13, 1997; accepted January 21, 1997.
| References |
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