Transcatheter closure of the atrial septal defect and other cardiac defects: current status

摘要

Introduction Ever since device closure of congenital cardiac defects has become available, more patients are undergoing device implantation and its acceptability has increased. Since ASD device closure is not only the most common procedure, but also the most representative of intracardiac device use, it is being discussed 111 detail here. Itis not out of place to critically review the current literature of device closure for (ASD’s) from the viewpoint of the pediatrician. Though it is likely that given a choice, majority of parents will opt for device closure, but. an informed decision-making is imperative. Surgical ASD closure Surgical outcomes will always be considered the gold standard with which the cardiologists will have to compare then results with. The outcomes of surgical ASD are well known and well described. This was the first congenital open heart surgery undetaken 111 early 1951. With the 50 year follow up available, it now well known thatcurrently the surgical risk of ASD closure by surgery is less than 1%; though the morbidity is much higher. Apait from the scar on the chest, there is no longterm implication if the ASD is repaired at the right time, without preceeding arrhythmia, pulmonary hypertension or any associated defects. It cannot be forgone though, that there is an atrial scar involved in the treatment for closure of the atriotomy through which the ASD is visualized and closed. There is no such atrial scar in device closure. It must be emphasized it is not truly appropriate to compare the two procedures since not all ASD, s can be closed by devices while all ASD’s can be closed by surgery. The scope of the two procedures is different. History of device closure Ever since the pioneering transcatheter device closure of a secundum atrial septal defect by King[1] In 1974 and the subsequent work of Rashkind[2], cardiologists have been trying for this to be the preferred mode of treatment. The major technological problem has been delivery of a device up to several centimeters 111 diameter via a catheter only a few millimeters 111 diameter. The first device used by king required a 23f sheath. Subsequently the clamshell device, a modification of the Rashkind device was delivered through an 1 If sheath. The sideris button device can be delivered through an 8f or 9f sheath. The other devices i.e. cardioseal (llf), angelwings (1 If) and the ASD occluder system device (lOf) also require large delivery sheaths. The major development of the amplatzer device was its delivery through a 7f & 8f sheath making it possible to close ASD’s in younger children also. This technological advancement took place only due to the useof Nitinol material for cardiac devices. After initial trials, the amplatzer device was approved for clinical use in the united states by the FDA in 2001. The Amplatzer ASD device Though there are several devices in use currently, most notably being the Starflex. Cardioseal Sideris and the Helex, it is the Amplatzer devices for ASD closure, which has maximum clinical use (Table 1). There are several reasons for this, it is best described as a self-centering, self-expanding, repositionable device. The design of the device constructed with 0.004-0.005 inch Nitinol is superior to the Sideris button device. The 2 discs are connected to each other via a waist. The waist equals the stretched diameter of the ASD. For devices in the range of 11-26 mm, the left atrial disc measures 14 mm more than the waist and the right atrial disc 10 mm more than the waist. This is the only device dependent on endothelial covering over the device for closure of the ASD. The profile of this device is probably the highest amongst the available devices, though newer designs of the device with lower profile are available especially for ventricular septal defects.Table 1: Characteristics of Amplatzer deviceThe other advantages include the ability to reposition the device without damaging it and its ease of implantation, which signif