Abstract
Thoracic aortic dissection (TAD) is a medical emergency which can present with a variety
of symptoms. It is vital to rapidly identify and diagnose this condition to increase
the patients’ chances of survival. Computed tomography (CT) and Magnetic resonant
imaging (MRI) are the standard diagnostic modalities, however these are normally carried
out outside an emergency department (ED), which could delay diagnosis and delivery
of care.
Transthoracic Echocardiography (TTE) is an accepted first line imaging modality in
the ED. This has been previously reported by the European Association of Echocardiography
[1], and ultrasound is becoming widely available and used in EDs nowadays. The aim of
this article is to present a case in which bedside ultrasound with focused cardiac
examination (FOCUS) was utilised to provide a rapid diagnosis of a clinical suspected
aortic dissection.
Case
This case reports a 55-year-old male who was admitted to the ED at Akershus University
Teaching Hospital, Norway. The symptoms included chest pain radiating to the left
jaw, with concomitant visual disturbances to his left eye. He was a former smoker
and had a history of asthma and borderline hypertension. On admission, the patient
had no complaints except for mild pain in his left jaw and chest as described previously,
with now a normalised vision. The physical examination showed a significant blood
pressure difference in the upper extremities; 135/85 mmHg on left arm and 100/70 mmHg
on right arm. Other vital signs were unremarkable. He had a strong holosystolic cardiac
murmur, which was not previously described. There were no palpable masses in the abdomen,
and the neurological examination was normal. ECG was without signs of acute ischemia.
His lab test showed haemoglobin of 15.4 g/dL, CRP 3 mg/L, ALAT 65 U/L, creatinine
104 µmol/L, troponin T 9 ng/L, NT-proBNP 67 ng/L and lactate 3.1 mmol/L.
Bedside ultrasound with FOCUS revealed a dilated aortic root of 53 mm ([Fig. 1]) and a proximal ascending aorta of 43 mm ([Fig. 3]). The FOCUS parasternal long axis projection and suprasternal projection, showed
an intimal flap in the aortic arch and ascending aorta extending down to the aortic
valve. This can be visualised in [Fig. 2], [4], [5] below. There was a moderate aortic regurgitation ([Fig. 5]), which was presumed secondary to the aortic dissection. There was no pericardial
effusion, and the abdominal aorta was not examined.
Fig. 1 2D Parasternal long axis view, visualisation of a dilated aortic root 53 mm (yellow
line).
Fig. 2 2D Parasternal long axis view with visualisation of intimal flap in the aortic root
(yellow arrow). Ao: aorta; RV: right ventricle; LV: left ventricle; LA: left atrium.
Fig. 3 2D Parasternal long axis of aorta with visualisation of a dilated aortic ascendens
43 mm (yellow line).
Fig. 4 2D Suprasternal view of the aorta, with visualisation of intimal flap (yellow arrow)
in the aortic arch. AA: aortic arch; AD: aorta descendent; RP: right pulmonary artery.
Fig. 5 2D color doppler mode parasternal long axis, with visualization of a moderate aortic
regurgitation (white arrow) and intimal flap (yellow arrow). Ao: aorta; RV: right ventricle; LV: left ventricle; LA: left atrium.
A CT was requested and confirmed a Stanford type A aortic dissection from the aortic
valve to below the renal arteries. The patient was transferred to the thoracic surgery
facility at Oslo University Hospital and underwent urgent surgery.
Discussion
Thoracic Aortic Dissection (TAD) is a rare condition, with high mortality if untreated.
The estimated incidence is 5–10 cases per million, and of the most common underlying
medical condition is hypertension [2]. The symptoms and signs of TAD can be seen with other critical medical conditions
and is very variable in presentation. Chest pain is present in up to 90 % of patients
upon admission [3].
Survival rates are increased with early diagnosis, especially when the dissection
involves the aortic root which can cause a secondary myocardial infarction or aortic
valve failure [4]. The mortality rate is as high as 1 % per hour in the first 48 hours without the
provision of the necessary treatment [4]. It is deemed important for clinicians to maintain a high level of suspicion to
detect the diagnosis and provide treatment as early as possible. CT and MRI are current
standard diagnostic modalities which have largely replaced aortography [5]. Nowadays TTE is widely accessible to emergency physicians, and a focused examination
of the heart is a part of ultrasound performance protocols utilised bedside in different
settings in emergency departments. Standard imaging of a focus cardiac ultrasound
examination (FOCUS) usually includes parasternal long axis, parasternal short axis,
and apical view of the heart. The sensitivity and specificity for ultrasound for detection
of aortic dissection has been shown to be high in selected studies [6], but the true sensitivity and specificity is probably variable depending on the
level of experience of the operator performing the examination [7]. Although two echocardiographic features are strongly suggestive of thoracic aortic
dissection; visualization of dilatation of any segment of the aorta, and visualisation
of an intimal flap in the aorta [8]. FOCUS in combination with certain clinical risk factor for diagnosing aortic dissection
also results in high sensitivity and specificity for diagnosing of Aortic Dissection
[9].
Conclusion
Bedside ultrasound with FOCUS can be performed by emergency physicians as a screening
tool in patients with suspected thoracic aortic dissection. The examination can be
performed in a very short space of time, rendering it a very efficient modality of
diagnosis for well-trained emergency physicians. This will ensure patients’ diagnosis
efficiently and ensure further aortic imaging or urgent surgical evaluation where
indicated. Ultrasonographic sign of an intimal flap of the aorta, and aortic segment
dilatation has been shown to be sensitive and specific for the diagnosis of thoracic
aortic dissection, which was found in our case. It is important to note that FOCUS
cannot be used as a standalone test to rule in or rule out thoracic aortic dissection.
