The Amplatzer membranous ventricular septal defect occluder has two discs of unequal size (Amplatzer Membranous VSD Occluder, AGA Medical Corporation, St. Jude, MN). The aortic rim of the asymmetric left ventricular disc exceeds the dimensions of the connecting waist by only 0.5 mm, so as to avoid impingement on the aortic valve, whereas the apical end is 5.5 mm larger than the waist. This apical end of the left ventricular disc contains a platinum marker to facilitate correct orientation during implantation. The right ventricular disc is symmetrical, and it exceeds the diameter of the connecting waist by 2 mm throughout its circumference (Fig. 28.2). The device is available in sizes from 4 to 18 mm and requires delivery sheaths from 7 to 9 French.

A MVSD Amplatzer device II is also available. It was redesigned to prevent conduction abnormalities with a 75 % reduction in radial force, 45 % reduction in clamping force and 10 % increase in stability. The left disc of this new device has an elliptical and concave shape that adapts to the LV outflow tract. It is available in two configurations:

The waist length is increased from 1.5 to 3 mm, and the waist diameter ranges from 4 to 10 mm in 1-mm increments plus 12 and 14 mm. Polyester patches are sewn into the discs.

The delivery system consists of a delivery cable and a pusher catheter having a sharp curvature of 180° inferiorly. This allows correct orientation of the left ventricular disc during implantation. It has a flattened part of the socket that matches the flat portion of the microscrew, in order to force larger part of the left ventricular disc to be oriented downwards so that it points to the left ventricular apex.

Left ventricular angiographies are obtained in axial projections for best evaluation of VSD size and position, in addition to TEE views. Left ventriculography in the hepatoclavicular projection (35° left anterior oblique/35° cranial) is performed to imaging mid-muscular, apical posterior defects. Anterior defects are better seen in 60° left anterior oblique/20° cranial (Fig. 28.3).

The VSD is crossed from the left side by using a right Judkins catheter and a soft Glidewire (0.035″, J Tip, Terumo); the wire is advanced to the pulmonary artery or to the SVC/IVC, where it is snared with a GooseNeck Snare (Microvena Corporation, 20–25 mm in adults, 10–15 mm in children) and exteriorized out of the right internal jugular vein or femoral vein establishing an arteriovenous circuit (Fig. 28.4).

Over the circuit, an appropriate size delivery sheath is advanced from the vein all the way until the tip of the sheath is in the ascending aorta. The dilator is withdrawn, and the sheath is pulled back in the left ventricle.

When the tip of the sheath is placed in the mid cavity of the left ventricle, the dilator and the wire are gently removed; a left ventriculogram is usually repeated, to confirm the position of the long sheath and also to obtain additional information on the position and the size of the VSD.

According to both angiographic and echocardiographic information, a muscular VSD occluder 1–2 mm larger than the maximum size of the defect is chosen.

The device is attached to the delivery cable, loaded into the plastic loader, introduced and advanced into the sheath.

The left disc is deployed in the left ventricular cavity, making sure it is not impinged in mitral valve apparatus, then the entire system is withdrawn towards the septum (Fig. 28.5a), and the central waist and the proximal disc are deployed; a test angiogram is done to verify the correct position of the device (Fig. 28.5b).