Why The Modified Occluders Can Decrease The Incidence Of Cavb In Device Closing Pmvsd?
Quansheng Xing, Qin Wu.
Women and Children's Hospital of Qingdao University, Qingdao, China.
OBJECTIVE: Perimembranous ventricular septal defect (pmVSD) is the most common congenital heart defect. Although effective, transcatheter closure of pmVSD using Amplatzer occluder has been associated with a substantial risk of complete atrioventricular block (cAVB), prompting many centers to abandon this intervention. However, percutaneous or perventricular closing pmVSD using modified occluder has widely been applied with promising results in China. The purpose of this study was to describe the characteristics of Amplatzer and modified pmVSD occluders in shape and structure, to clarify the potential reason of cAVB.
METHODS: All published studies about device closing pmVSD were searched and meta-analyzed. Amplatzer and modified pmVSD occluders were collected and compared. We designed and used new concentric occluder to close most pmVSD.
RESULTS: From the data published, we calculate the incidence of cAVB to be 3.8% and 0.15% in the Amplatzer and Chinese modified occluder group, respectively. The modified occluders has two remarkable changes. Firstly, the occluder waist-height was enlarged, from 3mm to 7mm with 1mm increment. Otherwise, the Amplatzer occluder has only one waist-height specification of 1.5mm. From the viewpoint of the cardiac surgeon, properly increasing the waist-height of the occluder, corresponding to the thickness of intraventricular septum, will alleviate entrapment of adjacent intraventricular septum, and then theoretically minimize cAVB. Secondly, the concentric occluder is more stable in vivo, and easier to deploy than eccentric ones.
CONCLUSIONS: The structure of the occluders is the determinant of severe AVB. Chinese modification may be an important reference and enlightment for further redesigning new pmVSD occluders.
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