Left atrium is excellently visulaised in para sternal long axis view . . . still , the vital feeding vessels to this chamber ,Th

The most famous and popular view in clinical echocardiography is para sternal long axis view.It gives us an instant information about the status of left atrium , left ventricle and aorta.Left atrium appears to be seen in full. Still , one should realise it is far from truth.There is a huge blind spot  for left atrium in this view .

For a complete imaging of LA one need to do a short axis view at aortic level, and of course a 4 chamber view . All these three views put together , can at best give a 80%  exploration of LA .The rest of the  20%(  some times vital !) can be seen only be transesophageal echo .

Why para sternal long axis fail to give even glimpse of the 4 pulmonary veins ?

• Pulmonary veins are probably ,  the most vital structure  in LA . There are 4 veins , generally  arranged in 2 pairs

• Unfortunately all these 4 veins does  not  interrupt the ultrasound beam in this view .The beam in para sternal view crosses  the anterior and lateral surfaces and to a  very small area of inter atiral septum(  IAS )

• These enter  the posterior surface of the LA in an oblique angle . The angle of entry is widely variable .Some times they need to run a parallel course with LA posterior wall . This makes recognition and delineation  of PV from LA very difficult ..

• Since all   4 pulmonary veins are located in the posterior aspect of LA ,  they  are best visualized either in apical 4 chamber (Right pulmonary veins) or short axis views(Left pulmonary veins)

When can pulmonary veins visible in PS- LAX view ?

When PVs take an abnormal course like in TAPVC or when they enter coronary sinus etc .

Rarely ,  huge LA enlargement may pull or push the PVs and make them visible in LAX view.

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