Eustachian valve-Masquerading ASD rim.

Sir,

The Eustachian valve (EV) is a frequent great mimic as evidenced by the elegant report by Raut et al. They have demonstrated how it can potentially complicate a simple percutaneous device closure of atrial septal defect (ASD). The free end was initially confused with superior rim of ASD in transesophageal echocardiographic (TEE) bicaval view. Only careful examination in other views with rotation of the probe revealed the large EV.

During surgery, EV could be mistaken for the true septum and inadvertently incorporated into the patch. This causes iatrogenic right to left shunt due to diversion of the inferior vena caval (IVC) blood flow into the left atrium. Persistent EV is seen in 70% of children of various ages and TEE is the gold standard in its diagnosis. While we emphasize the need for careful echocardiographic interrogation in all cases of ASD, we would like to share our technique of distinguishing EV from true septum in doubtful cases. In our centre, we employ two techniques for this:

A saline injection is given to identify EV in doubtful cases. Since EV is derived from the embryonic right valve of the sinus venosus, it is an entirely right atrial structure. It lies on the anterior border of IVC while the true atrial septum will be on the posterior border of IVC. Thus, saline injection will be posterior to EV, but anterior to a true septum (Fig. 1, panel A, video 1).

Fig. 1

Panel A: Transoesophageal echocardiography showing saline contrast injection (saline) posterior to Eustachian valve (EV); RA = right atrium. Panel B: three dimensional transoesophageal echocardiography showing the anterior Eustachian valve (EV) separately from true septum (septum) which is posterior; RA = right atrium.

Three dimensional echocardiography will clearly separate EV from the true septum (Fig. 1, panel B, video 2).