Study on the Safety and Effectiveness of the SnowyTM PFO Closure System

Inclusion Criteria: 1. Age: 18 to 65 years old, regardless of gender 2. Transthoracic echocardiographic contrast echocardiography (cTTE) confirmed the presence of PFO and at least moderate (see above definition) RLS (in Valsalva active/resting state) 3. Existence of at least one of the following conditions： 1) Unexplained stroke or TIA 2) intractable or chronic migraine 4. The subjects are informed of the nature of the study and agreed to all requirements for participation in the study, signed the informed consent form, and agree to complete the follow-up and follow-up examination Exclusion Criteria: 1. Patients have definite causes of stroke unrelated to the PFO 2. RLS caused by other causes, such as atrial septal defect or pulmonary arteriovenous shunt 3. Atrial fibrillation or atrial flutter 4. Mitral and aortic stenosis or severe regurgitation 5. Dilated cardiomyopathy, hypertrophic cardiomyopathy, restrictive cardiomyopathy 6. Active endocarditis or other untreated infectious diseases 7. Left ventricular ejection fraction (LVEF) \< 40%, or NYHA cardiac function grade III-IV 8. Uncontrollable hypertension 9. Previous intracardiac surgery 10. Myocardial infarction or unstable angina pectoris within 6 months 11. Contraindications to anticoagulants or antiplatelet drugs 12. High risk of bleeding 13. severe liver function impairment（alanine aminotransferase (ALT) or aspartate aminotransferase (AST) greater than 3 times the upper limit of normal value） 14. Serum creatinine greater than 2 times the upper limit of normal or with any history of renal dialysis or renal transplantation 15. Severe pulmonary disease including pulmonary hypertension (clinical diagnosis) 16. Nickel or contrast allergy 17. Active or planned (within 12 months) pregnancy, or lactating female patients 18. Malignant tumors or other serious diseases resulting in a life expectancy of less than 12 months 19. Psychiatric conditions that may interfere with medical compliance and compliance with follow-up 20. Concomitant participation in other clinical trials 21. The investigator determines that the patient is unsuitable because of reasons not listed but thought to interfere with safe trial participation