4.2 Spontaneous PIVSD closure
What we know about the option of occluder device is primarily based upon empirical studies that the conventional devices were ASDo, mVSDo and PimVSDo. There were no related articles about the comparison of varieties of devices, so it is uncertain which type of device is the best choice for catheterization. However, surveys such as those conducted by Szkutnik et al[24] and Wacinski et al[25] have shown that PimVSD is more suitable for PIVSD owing to the particular structure (wider waist, larger disks and a denser construction ) could occlude moderate to severe shunt in a short period time.
The location and size of the device were detected by two-dimensional transthoracic echocardiography (2DTTE) in a large number of studies, with a sizing balloon to determine the size in minor cases. However, it is taking the risk of enlargement of the defect, whether this method can be adopted depends on the firmness of the rims and the anatomic morphology of VSD[15,26]. Recently, several attempts have been made to use three-dimensional transthoracic echocardiography (3DTTE) or three-dimensional transesophageal echocardiography (3DTEE) to assess the VSD. Many analysts now argue that the strategy of 3DTTE/3DTEE over 2DTTE has been successful for the evaluation of VSD following AMI, for example, argues that VSD shape and its changes during the cardiac cycle can be visually and quantitatively displayed. 3DTTE/3DTEE may thus be particularly useful before and during percutaneous VSD closure[27-29].
There is still no definite conclusion about how to select the size of the device. Data from several experienced articles have identified the optimal diameter should be twice the size of the measured defect diameter or at least 10 mm larger,it can prevent incomplete closure or dislocation and embolization of the device due to continued septal necrosis in the acute phase[30-31], in turn, the occluder size was slightly larger than the measurable defect size in the chronic phase[24]. As for the best timing of TCC after AMI, there were two contrary opinions, majorities of people hold the idea that the delay of 10-14 days may help for shaping the scarred tissue to restore the perforation tissue and improving the NYHA classification ,so that can acquire the better progression[16]. The others consider the percutaneous closure should do as quickly as possible because of prolonging the time was not associated with the low mortality[15]. However, there was no direct evidence to justify which choice could decrease the mortality effective. When treated with PIVSD, one-key to success in procedure was immediate complete or partial shunt reduction.Our data confirmed about 80.9% shunt got to reduce after interventional surgery. Just like Calvert et al[15] indicated that if the shunt cannot decrease at least two thirds, the patients are most unlikely to survive either to surgery or to discharge. Moreover, there is no apparent distinction between a variety of occlusion devices, which depends on the edge condition and size of defects identified by echocardiography. As a rigorous surgical procedure requiring expertise and collaboration between interventionists, anesthetists, and echocardiography specialists.