Keywords
aortic dissection - pulmonary embolism - concomitant
Introduction
Chest pain is a common presenting complaint accounting for millions of emergency department
(ED) visits. Diseases of the heart, aorta, lungs, esophagus, stomach, mediastinum,
pleura, and abdominal viscera may all cause chest discomfort. Clinicians in the ED
focus on the immediate recognition and exclusion of life-threatening causes of chest
pain such as acute coronary syndrome, acute aortic dissection (AAD), and pulmonary
embolism (PE). A thorough medical history, with particular emphasis on the onset and
quality of pain and associated symptoms, followed by a detailed physical examination
is of central importance to organize appropriate investigations. Nevertheless, often
these pathologies can be clinically difficult to differentiate especially when they
coexist. AAD and acute saddle PE, although very rarely, can present simultaneously;
we present a case where this unique high-risk scenario was promptly diagnosed and
successfully managed with concomitant aortic repair and pulmonary embolectomy. To
our knowledge, this has not been reported before.
Case Presentation
A 75-year-old man presented at our ED 2 hours after sudden onset of severe central
chest pain that followed a straining effort; the pain was described as sharp, radiated
between the scapulae, and was associated with palpitations and dyspnea. The only relevant
past medical history was a spontaneous superficial thrombophlebitis a month prior;
this was managed in the community without anticoagulation. The physical examination
revealed an aortic regurgitation murmur and chest X-ray showed a moderately enlarged
mediastinum. An urgent computed tomography (CT) pulmonary angiogram was organized
([Fig. 1]); this showed (1) a large saddle pulmonary embolus extending into both left and
right pulmonary arteries, (2) a dilated 7 cm ascending aorta with an apparent flap,
and (3) a hemopericardium (Hounsfield Unit 30). Given the highly suspicious appearance
of the ascending aorta, a CT angiogram was then performed confirming acute type A
dissection. The dissection flap involved the ascending aorta and the aortic arch,
sparing the supra-aortic vessels; a thrombosed false lumen extended into the descending
thoracic and abdominal aorta just above the renal arteries ([Fig. 2]). An urgent transthoracic echocardiogram confirmed the diagnosis and documented
severe aortic regurgitation. At this stage, the patient was hemodynamically stable;
decision was made to proceed immediately with aortic dissection repair and pulmonary
embolectomy.
Fig. 1 Computed tomography pulmonary angiogram showing large saddle pulmonary embolism in
axial (A) and coronal (B) views. The ascending aorta is dilated and presents intraluminal abnormalities suspicious
of an intimal flap.
Fig. 2 Computed tomography aortogram confirming the diagnosis of acute type A aortic dissection.
Femorofemoral bypass was established and at pericardiotomy a large hemopericardium
was evacuated. The aorta was transected under deep hypothermic circulatory arrest
(18°C) with retrograde cerebral perfusion. The entry tear was found in the anterior
wall of the ascending aorta with fresh clot within the false lumen. The aorta appeared
to be ruptured posteriorly with just a thin layer of clot tamponading against the
main pulmonary artery bifurcation, preventing free intrapericardial rupture.
The ascending aorta was replaced with a 38 mm Dacron graft. After performing the distal
anastomosis just proximal to the innominate artery, cardiopulmonary bypass was re-established
and the main pulmonary artery was opened longitudinally. Embolectomy of a large saddle-shaped
pulmonary thrombus (6 cm long) was then performed using Rampleys forceps. No attachment
to the pulmonary artery intima was noted, confirming the acuteness of the embolic
event.
Finally, the aortic root was replaced with a 29 mm Medtronic Freestyle stentless bioprosthesis
(Medtronic). The patient was weaned off bypass uneventfully and transferred to the
intensive care unit in stable condition.
The postoperative course was unremarkable. No deep vein thrombosis or thrombophilic
traits were identified. Pathology of the pulmonary embolus showed characteristic lines
of Zahn, indicating a recent event. The patient was discharged home on lifelong warfarin
on postoperative day 10.
Discussion
Acute aortic dissection accounts for 85 to 95% of all acute aortic syndromes and its
incidence is ∼15 cases per 100,000 patient-years. Chest or back pain, often described
as “sharp,” is the most frequent presenting symptom (84.8%). Hypotension, pulse deficit,
and acute heart failure are the most common physical findings.[1] In the general population, the incidence of PE has increased to 112 cases per 100,000
patient-years and patients usually present with dyspnea and pleuritic chest pain.
Saddle embolus accounts for 3 to 6% of PE cases. Those patients are more likely to
experience hemodynamic instability and their acute mortality is 5%.[2]
AAD and PE can mimic each other clinically. Rapid differential diagnosis is critical
to establish the correct treatment and improve outcome. D-dimer is a biomarker with
good sensitivity (93.5%) but low specificity (54%) for AAD.[3] In the diagnosis of PE, sensitive D-dimer testing is mostly useful in conjunction
with clinical suspicion to guide further investigations. Triple-rule out (TRO) CT
angiography to simultaneously evaluate acute coronary syndrome, acute aortic syndrome,
and PE is increasingly being performed in institutions where a 64-slice multidetector
CT scanner is available. Despite its valuable role, TRO carries a higher radiation
exposure due to the extended z-axis coverage. For these reasons, Lee et al suggested
that the use of dedicated coronary CT angiography (DTCA), instead of a TRO protocol,
is equally safe when triaging patients with nonspecific acute chest pain.[4] Pulmonary transit time needs to be taken into account when performing DTCA in this
scenario to avoid a false-negative diagnosis of PE.[5]
Transesophageal echocardiography is comparable to a CT angiogram for sensitivity and
specificity in the diagnosis of AAD.[1] However, echocardiography cannot definitively diagnose PE. In stable patients, it
may be used when other tests are inconclusive and clinical suspicion remains high.
About 30 to 40% of patients with massive PE have echo signs of right ventricle (RV)
strain or overload, like RV enlargement, RV dysfunction, or tricuspid regurgitation.
However, in case of AAD with intrapericardial posterolateral rupture, the compression
onto the main pulmonary artery can result in acute RV dilatation and dysfunction,
resembling the appearance of a massive PE.[5]
Although differential diagnosis is crucial, physicians should bear in mind that on
rare occasions aortic dissection and PE can coexist. This has important implications
in the decision making and management plans. Type A dissection with associated embolism
of the right main pulmonary artery was reported by Leu and Yu; the patient refused
surgery and died few months after.[6] More recently, another case of acute type A dissection limited to the ascending
aorta and concomitant lobar PE was reported by Tudoran and Tudoran; the patient underwent
successful aortic surgery 1 month after the diagnosis.[7] Finally, peripheral PE associated with acute type A dissection was described by
Herrera et al in a patient with Marfan syndrome and hyperhomocysteinemia, who survived
aortic surgery.[8]
In our case, the patient presented with sudden onset of sharp chest pain without other
associated symptoms. The history of recent thrombophlebitis led the ED physician to
investigate with a CT pulmonary angiogram that revealed a large saddle PE. The observation
by an alert radiologist of a dilated and abnormal ascending aorta prompted a completion
CT aortogram, confirming the suspicion of simultaneous type A dissection. Correct
diagnosis of concomitant pathology was crucial; establishment of therapeutic anticoagulation,
in fact, would have carried devastating consequences in the setting of intrapericardial
rupture of the dissection.
In conclusion, AAD and saddle PE, although very rarely, can present simultaneously.
Emergency clinicians must guard against premature diagnostic closure when assessing
patients presenting with acute chest pain.
