Transthoracic Echocardiographic Diagnostic Accuracy in Detecting "Type-B" Aortic Dissection.

We present a case of a 91-year-old man presenting to the emergency department with a tearing back pain. The patient's history included an endovascular abdominal aortic repair because of an aneurysm. The transthoracic echocardiography (TTE) appeared normal; however, when transducer was positioned to the left of the spine for the posterior paraspinal window, a clear intimal flap was demonstrated in the descending aorta lumen. The multiphasic computed tomography of the aorta confirmed the diagnosis of Stanford Type-B aortic dissection. The patient underwent thoracic endovascular aortic repair, consisting of a descending aorta endoluminal graft placement and realizing a full metal jacket thoracic-abdominal aorta. At 3-month follow-up, the outcome appeared excellent. The case points out the usefulness of TTE via nonconventional windows in detecting Type-B aortic dissection. Copyright:

INTRODUCTION

Transthoracic echocardiography (TTE) is widely used in the emergency setting as part of a multidisciplinary approach to rapid diagnosis.[1]

However, its accuracy for acute aortic dissection (AAD) remains relatively low.[2]

In a recent update, Bossone et al.[3] stated that TTE sensitivity is 78%–100% for Type-A AAD and only 31%–55% for Type-B AAD.

Through the following clinical case, we would like to postulate that TTE – using a nonconventional window – may be crucial in detecting the Type-B AAD.

CASE REPORT

A 91-year-old man presented to the emergency department with sudden upper back pain, vomiting, and dyspepsia. He was on warfarin therapy for permanent atrial fibrillation. The patient's previous history included hypertension, dyslipidemia, peptic ulcer disease, and an aorto-bisiliac endovascular graft placement 7 years before because of an abdominal aortic aneurysm extended to both iliac branches. Initial clinical parameters included blood pressure measurement of 190/99 mmHg and heart rate of 70 beats per minute. Physical examination revealed mild bibasal lung crepitations and a nontender abdomen. Chest X-ray demonstrated pulmonary congestion. The patient underwent TTE (by E9 Machine, GE, Boston, USA) in the left lateral decubitus position, using a sector transducer. TTE – via the parasternal, apical, and subcostal windows – did not demonstrate aortic lesions, while – via the left posterior paraspinal window – a clear intimal flap in the descending thoracic aorta (DTA) lumen was demonstrated [Figure 1 and Video 1]. Chest computed tomographic (CT) scan confirmed an intramural hematoma of the distal arch and a Type-B thoracic aorta dissection [Figure 2]. The patient developed hemodynamic deterioration and was treated by emergent thoracic endovascular aortic repair realizing a full metal jacket thoracic-abdominal aorta [Figure 3].

Figure 1

Transthoracic echocardiography – posterior paraspinal window, long-axis view, demonstrating an intimal flap in the descending thoracic aorta lumen

Figure 2

Multidetector computed tomographic angiography demonstrating a complete thrombosis of the false lumen in the descending thoracic aorta (orange arrow)

Figure 3

Electrocardiographically-gated computed tomography aortogram (left) with three-dimensional volume rendering images (right) demonstrating a full metal jacket thoracic-abdominal aorta

At 3-month follow-up, the outcome appeared excellent.

DISCUSSION

It is well known that paravertebral views are unusual, poorly known and therefore rarely performed views.[45] These views may be useful for the assessment of pathology in the mid and distal segments of the DTA. Technically, the patient leans forward and the transducer is placed in both longitudinal and transverse scanning planes, along the left border of the thoracic spine [Figure 4a and b]. The transducer is moved from cephalic to caudal to assess most segments of the DTA. The presence of left pleural effusion improves the visualization of the DTA, since the pleural fluid displaces the air in the lung and consequently enhances the acoustic interface between the thoracic wall and the aorta.[4]

Figure 4

The transthoracic transducer is positioned to the left of the spine for the posterior paraspinal window. The transducer is rotated to obtain long-axis (a) and short-axis (b) view

CONCLUSION

Physicians and sonographers have to consider that in some cases, even in the absence of pleural effusion, paravertebral views are helpful for the noninvasive evaluation of the DTA, allowing better identify and characterize aortic disease.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.