Emergency Echo 5Es

E is for Exit

  • Thoracic aortic root
  • Best seen on parasternal long axis
    • Not all aneurysms dissect
    • Not all dissections are aneurysmal
    • But there is a strong association
  • Measure outside wall to inside wall (leading edge method)
  • At sinuses of Valsalva, or widest part
    • Normal <4.0cm
    • Borderline 4.0-4.5cm
    • Aneurysmal >4.5cm
sonogram sensor position


So the fourth of our five E's is the exit, and that is really the thoracic aortic root as it exits the left ventricle. This is best seen on a parasternal long axis and the reason we look at it is because it can be a clue for possible thoracic aortic dissection or aneurysm. It is important to understand that not all aneurysms dissect, and not all dissections are aneurysmal, but there is a strong association. So, when you see somebody with symptoms like chest pain, syncope, shortness of breath and they have a dilated thoracic aortic root you should consider the possibility of an aortic aneurysm or a dissection going on that could be causing symptoms. In order to measure this we go from the outside wall to the inside wall, which is called the leading edge method, it is the first edge that the ultrasound beam hits going from proximal to distal, and ideally we measure it at the sinuses of Valsalva, the little outpouchings right at the beginning of the aortic root, and that's often the widest part. Although, you have to keep your eyes open sometimes it gets wider after, we'll show some examples of this, and really you want to measure the aorta at the widest part. We consider normal under 4 cm, borderline about 4-4.5 cm, sometimes these will still be normal on CT if you do them, but when you measure it on echo and it is over 4.5 cm it is definitely abnormal.

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