Jonathan D. Dodd, MB, David O'Donnel, MB, Ronan Killeen,
MB, Ronan Ryan, MB, Peter Quigley, MB,
Martin Quinn, MB,
St. Vincent's University Hospital, Elm Park, Dublin,
A 73-year-old woman was admitted for the investigation of
atypical, intermittent chest pain and dyspnea. Her chest pain came
on suddenly, was not relieved by nitrates, and did not radiate. It
continued to occur intermittently throughout her hospital stay but
remained stable in severity. Her dyspnea was more gradual in onset,
was mild initially, and became progressively worse over the course
of her stay. Her surgical history was significant for an aortic
valve replacement 20 years previously for aortic stenosis. She did
not suffer from hypertension and was a nonsmoker. Her medications
included anticoagulation for her prosthetic valve.
On examination, the patient had a mild tachycardia (100 bpm) and
normal blood pressure. An ejection systolic murmur and click was
auscultated over the aortic area. Her electrocardiogram, serum
troponin, and chest radiograph were normal. Over the next 10 days
she remained stable, but her intermittent chest pain persisted and
her dyspnea progressed. Because of her continuing atypical chest
pain, she was referred to invasive coronary angiography. The
cardiologist was unable to engage the coronary arteries. An aortic
angiogram was performed and the aortic lumen was found to be widely
dilated (Figure 1). A large outpouching was noted arising from the
posterior wall of the ascending aorta.
The patient was transferred urgently to the radiology
department, where she underwent 64-slice cardiac CT (Siemens
Sensation, Erlangen, Germany) to further evaluate the aorta and
coronary arteries. Technical parameters included 375-msec rotation
time, 0.75-mm slice thickness, 0.4-mm overlap, kVp 120, 850 mAs,
pitch 0.2, 120 mL of Niopam 370 (Bracco UK, Ltd., High Wycombe, UK)
(using the test bolus technique), and image reconstruction with
retrospective electrocardiographic (ECG) gating. The images showed
a Stanford type A aortic dissection. A portion of the dissection
had partially ruptured through the posterior aortic wall to form a
large pseudoaneurysm (Figure 2). The pseudoaneurysm was causing
significant external compression on the right main pulmonary artery
(Figure 3). The 64-slice cardiac CT images clearly showed extension
of the dissection ﬂap to involve the ostium of the left
main (LM) coronary artery (Figure 4A). The right coronary artery
ostia appeared uninvolved (Figure 4B). Based on the cardiac CT
findings, surgical repair included an LM coronary reimplantation in
addition to an aortic root and valve replacement. The patient made
a full, immediate postoperative recovery.
Recent developments in CT technology have led to its increasing
application for acute chest pain. For our patient, it provided
valuable preoperative information on the extension of the
dissection ﬂap to involve the LM coronary artery, as
well as the presence of a large pseudo-aneurysm. Technically, if a
dissection does not involve the coronary arteries, then the aortic
graft repair is performed as a supracoronary procedure, and the
native aortic shell becomes wrapped around the graft. If the
coronary arteries are involved by the dissection, coronary graft
reimplantation (Bentall procedure) is necessary.
Thus, in acute aortic dissection, coronary artery involvement plays
a major role in the type of surgical procedure performed.
Traditionally, the coronary arteries have not been evaluable with
CT. The rapid motion of the heart resulted in excessive motion
artifacts, precluding robust assessment of the coronary ostia in
the context of aortic dissection.
Newer CT techniques involving data reconstruction with ECG-gating
allow images to be reconstructed at a particular part of the R-R
interval throughout scan acquisition. Usually, the best portion is
at 60% to 70% of the R-R interval, resulting in "motionless"
imaging of the coronary arteries. The images in the current case
were reconstructed at 65% of the R-R interval, allowing excellent
visualization of the proximal extent of the dissection to the LM
The application of CT angiography for patients referred with
chest pain is currently an area of intense research interest.
Several studies have shown cardiac CT to have a negative predictive
value of close to 100% in the exclusion of acute coronary syndrome.
Dedicated cardiac CT protocols are evolving to include a
"triple-rule-out" assessment for aortic dissection and pulmonary
embolism in addition to the coronary arteries, but these protocols
lack thorough clinical evaluation. Early studies have shown that CT
may provide excellent visualization of the coronary, pulmonary, and
Such technology developments are supporting recommendations that
cardiac CT may play an important role in the investigation of
patients presenting to the emergency department with acute chest
Cardiac CT with retrospective ECG-gating allows accurate
evaluation of coronary ostial involvement in acute aortic
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in: Circulation. 2006; 114:e651.
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