5. Limitations
There are several limitations in our study. First, studies enrolled in this meta-analysis are nonrandomized, observational design, thus selection bias is impossible to avoid. Second, the sample size included in the study is small which may affect the stability of the result indicators, reduce the efficiency of the test, and may bias the research results. Third, different studies were followed with different tests, which led to biased follow-up. In addition, clinical studies did not have uniform definitions of procedural success and procedure-related complications.