Mitral Regurgitation Percutaneous transcatheter interventions on the mitral valve to treat mitral regurgitation have become increasingly commonplace in adults, permitting clipping or suture of the leaflets to produce dual orifices, or by inserting devices within the coronary sinus to improve coaptation of the leaflets.23,24 These therapies are not yet routinely used in patients with congenital heart disease (CHD) Tricuspid Valve Congenital tricuspid valvar stenosis rarely occurs as an isolated lesion and is most commonly associated with hypoplasia of the components of the right heart Acquired stenosis in children is almost always due to rheumatic disease and virtually never occurs as an isolated lesion Balloon dilation of the stenotic tricuspid valve has been reported in parts of the world with high prevalence of rheumatic fever The basic principles of the techniques used are similar to those applied for mitral stenosis The Inoue balloon is most commonly used, albeit that double balloons can be used In congenital lesions, the associated hypoplasia of the right heart usually takes precedence in making management decisions Shunts Atrial Septal Defects Interventional catheterization is the first modality of treatment to close defects in the atrial septum when increased pulmonary blood flow has caused dilation of the right heart The morphology of the defect determines the suitability of the technique, those most suitable being the ones within the oval fossa with adequate margins at the rims Superior and inferior sinus venosus communications, those defects in the oval fossa with deficient or floppy margins, or large defects encroaching on surrounding structures or resulting in hemodynamic compromise or trauma are the general contraindications and may be better managed by surgical patch closure Any associated lesions, such as anomalous pulmonary venous drainage, should be ruled out prior to transcatheter closure There are many devices available to close the defects, and they vary in their ease of loading and deployment and their suitability for the morphology of the defect, along with safety, efficacy, and long-term behavior The most commonly used Amplatzer atrial septal occluder (Abbott Medical) consists of two discs of nitinol wire mesh connected by a waist of 4-mm thickness, which forms the central occluding disc (Fig 18.6) The device is available in different sizes depending upon the diameter of the central disc The left atrial disc is larger than the central occluding disc by 12 to 16 mm An Amplatzer Cribriform device (Abbott Medical) is also available for closure of multifenestrated defects This device has a much narrower waist to position it through one of the central defects, with the left and right atrial discs covering the surrounding holes This device has been commonly used for closure of the oval fossa, although a new purpose-built device currently exists (Amplatzer PFO Occluder) A Dacron polyester patch is sewn into the device to increase thrombogenicity The delivery system consists of a loading sheath to help collapse the device and load it into a long delivery sheath attached to a delivery cable The long sheath is angled at 45 degrees and has varying diameters and lengths The device is attached to the delivery cable with a screw-on mechanism allowing release of the device after satisfactory deployment Rates of closure are excellent when patients are selected in appropriate fashion FIG 18.6 The Amplatz septal occluder, with the left and right atrial discs connected by a waist The device is attached to a cable that is inserted through a delivery sheath (From Seivert H, Qureshi SA, Wilson N, Hijazi ZM, eds Percutaneous Interventions for Congenital Heart Disease London: Informa Healthcare; 2007.) The procedure is performed under general or local anesthesia with sedation Availability of transthoracic, transesophageal, and intracardiac echocardiography has been crucial to the safety and success of the procedure A catheter passed through the femoral vein is used to position the sheath across the defect The pulmonary vein is used as the site for anchorage of a stiff guidewire The defect is sized using echocardiography (to obtain a static measurement of the defect) and frequently also with a contrast-filled balloon inflated carefully across the defect (Fig 18.7A) Care must be taken to avoid stretching the defect.103 Color flow mapping and occlusion of flow by inflating a balloon, the stop-flow technique, are also used as techniques for sizing A device of size equal to or just larger than the size of the defect is commonly used It is delivered through the sheath across the defect under fluoroscopic and echocardiographic guidance, ensuring appropriate deployment, absence of obstruction to contiguous structures, and lack of residual shunting (Fig 18.7B) Successful anchorage is checked by wiggling the device while it is still attached to the delivery system, thus ensuring a secure position The device can be retrieved and redeployed to the satisfaction of the operator prior to release Various techniques used to deploy devices in larger defects include the use of specially designed sheaths with a double curve, a sheath positioned in the right upper pulmonary vein, a dilator, or balloon-assisted techniques that prevent prolapse of the left atrial disc across the defect FIG 18.7 Closure of an atrial septal defect with the Amplatz septal