THE THREE VESSEL (TRACHEA) VIEW  

 

This view demonstrates the relationship between the aorta, pulmonary artery and superior vena cava.

This view is obtained by angling the transducer cephalad from the four-chamber view to the level of the fetal mediastinum.

Vessels assessed include:

·         The main pulmonary trunk.

·         The ductus arteriosus.

·         The aortic arch and isthmus.

·         The superior vena cava (SVC) – lies to the right of the aortic arch.

·         Trachea – bright walled structure lying to the right of the great vessels and posterior to the SVC.

 

 

 

 

SVC – superior vena cava

Ao – ascending aorta

PA – pulmonary artery

DA – descending aorta

Tr – trachea

 

 

ULTRASOUND  

 

 

·         Sonographically convergence of the vessels at the level of the aortic isthmus and ductus arteriosus is “V-shaped”, with the apex of the “V” lying just anterior to the fetal spine.

·         The aortic and pulmonary trunks converge towards the left of the thorax (trachea is to the right).

 

 

Pulmonary artery bifurcation

Three vessel view

Blood flow towards the descending aorta in both the PA and transverse aortic arch

 

·         Pulmonary trunk is slightly larger than the aorta (1.2 to 1 ratio).

·         The vessels run a straight course.

·         Flow in both vessels are in the same direction (antegrade throughout the cycle) and are represented by the same color on doppler.

 

 

·         It is useful to assess:

o       Size of the three vessels i.e. whether any vessel is dilated or hypoplastic.

o       Alignment of the vessels.

o       Arrangement of the vessels.

o       Whether all three vessels are present.

o       Whether any additional vessels are present e.g. persistent left SVC.

o       Origin of the pulmonary arteries and whether they are aberrant e.g. arise from the aorta.

 

 

 

Normal variants

The brachiocephalic vein (innominate vein) is demonstrated by tilting the ultrasound beam cephalic from the three vessel view.

o       Formed from the junction of the left internal jugular and subclavian veins.

o       Drains into the superior vena cava.

 

Prominent Azygous vein

 

 

 

 

 

Video clip of Three Vessel View

 

 

 

 

 

 

 

 

 

 

 

 

REFERENCES

1. Yoo S-J. AJR 1999;172:825-830.