Whereas transcatheter methods for closure of atrial septal defects located in the oval fossa have become widely accepted as an alternative to surgical closure, defects located in the infero-posterior portion of the interatrial septum have, to our knowledge, not yet been reported to be amenable to transcatheter closure.^{1, 2} Even though many interventionists would classify defects located infero-posteriorly as inferior sinus venosus defects, demonstration of overriding of the intact inferior muscular border of the oval fossa by the mouth of the inferior caval vein is the anatomical prerequisite of that diagnosis, whereas abnormal drainage of an inferior pulmonary vein is not required.³ Without direct inspection of the interatrial septum, either during surgery or at post-mortem, these distinctions remain difficult, and have provided a matter of debate even for those using modern transesophageal echocardiographic equipment.^3–7 Whereas it may not be of clinical importance whether a defect of the inferior-posterior portion of the interatrial septum is classified as inferior sinus venosus defect or an atrial septal defect extending into the mouth of the inferior caval vein, it is important in our opinion to emphasize that such defects may be amenable to transcatheter closure, and their diagnosis should certainly not preclude an attempt at transcatheter closure. We report here, therefore, a novel technique for occlusion of such defects by opening the right atrial disc of an Amplatzer atrial septal occluder into the inferior caval vein and pushing it upwards toward the mouth of the inferior caval vein.

Case report

A 4-year-old patient was diagnosed by transthoracic echocardiography as having a defect within the oval fossa, and was referred for transcatheter occlusion of the defect. Cardiac catheterization was performed under deep sedation using a femoral venous approach. Hemodynamic measurements revealed a significant left-to-right shunt, with a ratio of pulmonary to systemic flows of 2.1. Transesophageal echocardiography revealed the defect to be within the inferior part of the oval fossa. But, in addition, the transesophageal study revealed a second defect located infero-posteriorly in close relation to the mouth of the inferior caval vein (Fig. 1a). To evaluate whether both defects could be closed by transcatheter means, we performed simultaneous balloon sizing using 2 Arrow sizing balloons (Arrow, Reading, PA, USA) introduced from both femoral veins through sheaths of 6 French dimensions. The stretched diameter of the infero-posterior defect was 10 mm, and the stretched diameter of the other defect within the oval fossa was 8 mm. In addition to transesophageal echocardiography, the location of the infero-posterior defect was evaluated by angiography in the right upper pulmonary vein using a Berman angiography catheter. During angiography, the balloon catheter was positioned to occlude the infero-posterior defect (Fig. 1b). The two defects were directly adjacent, as evidenced by the short distance between the balloon catheters during sizing. To confirm left-sided pulmonary venous drainage, and a sufficient distance from the mouth of the lower right pulmonary veins to the defect, wedge angiography of the right pulmonary artery was performed with layered contrast medium. For closure, a 12 mm Amplatz atrial septal defect occluder was introduced into the long sheath across the infero-posterior defect. The left atrial disc, and the central part of the device, were opened and pulled into the defect. The right atrial disc was released from the long sheath into the inferior caval vein. The delivery cable of the Amplatzer device was then pushed cranially, and the right atrial disc formed in close contact to the infero-posterior portion of the rim of the oval fossa.

Figure 1. Transesophageal echocardiography during balloon sizing of the defect at the mouth of the inferior caval vein with a very deficient inferior rim. There is a second inferior left-to-right jet inferior to the occlusion balloon (a). Right upper pulmonary venous angiography. (b) Simultaneous occlusion of the infero-posterior defect demonstrates the anatomical relations and insufficiency of the inferior rim.

Transesophageal echocardiography confirmed an adequate position for the device, with a sufficient distance to the coronary sinus, pulmonary veins, and the hinges of the atrioventricular valves. The device covered both defects with no residual shunting (Fig. 2). Angiography into the delivery sheath confirmed a perfect position for the device, revealing unobstructed flow of blood from the inferior caval vein into the right atrium. The device was then released from the delivery wire. The patient was returned to the ward and discharged 48 h after the procedure, after transthoracic echocardiography and fluoroscopy had confirmed the excellent result of the implantation. Follow-up echocardiography and fluoroscopy 4 weeks after the occlusion again demonstrated a perfect position of the device, and no residual shunt.

Figure 2. Transthoracic echocardiography (a), and the lateral projection of an injection made in the inferior caval vein (b), with the Amplatzer Occluder still attached to the delivery cable. There is no residual shunting, and no obstruction of the inferior caval vein.