TEER for Severe DMR of Low to Intermediate Surgery Risk

Inclusion Criteria: the patient fully meets the following criteria.

1. age ≥ 18 years old
2. DMR ≥ grade 3+ according to UCG integrative approach, referring to the followingquantitative indicators: 1) effective regurgitant orifice area (EROA) ≥0.3cm^2; 2)regurgitant volume (RVol) ≥45ml; 3) regurgitant fraction (RF) ≥40%.
3. symptomatic heart failure ( New York Heart Association (NYHA) class II-IV ), orasymptomatic heart failure with left ventricular end systolic dimension (LVESd) ≥40mmor ejection fraction (EF) ≤60%, or new-onset atrial fibrillation, or resting pulmonaryartery systolic pressure (PASP) >50mmHg.
4. The patient with American Association of Thoracic Surgeons Score (STS) <8 has surgicalindications evaluated by cardiac team.
5. The patient has signed an informed consent form and agreed to regular follow-up for atleast 1 year.

Exclusion Criteria: the patient meets any of the following criteria.

1. active infective endocarditis especially occurring in the mitral valve area, or mitralvalve perforation.
2. rheumatic mitral valve disease, mitral stenosis or mitral valve orifice area < 4mm^2.
3. combined valve lesions requiring surgery, e.g. severe tricuspid regurgitation oraortic valve disease.
4. the present of tumour, thrombus or redundant organisms in the heart chambers.
5. inability to tolerate intraoperative or postoperative antithrombotic (anticoagulant orantiplate) therapy.
6. acute DMR, e.g. DMR caused by acute papillary muscle rupture.
7. Due to the presence of certain anatomical conditions, patient has a low success ratefor TEER assessed by the operator and is not appropriate for enrolment. The conditionsinclude but are not limited to the followings: 1) the venous approach is not suitablefor operation, such as thrombus in the approach and small vein diameter; 2) severecalcification presents in the flap leaflet clamping area; 3) mitral valve cleft; 4)multiple regurgitant flow, especially in the internal and external union junctionarea; 5) Barlow disease; 6) leaflet length <7mm; 7) flail gap >10mm; 8) flail width >15mm.
8. severe cardiac insufficiency ( NYHA class IV or lefr ventricular ejection fraction (LVEF) <20% ), end-stage heart failure status ( American College ofCardiology/American Heart Association (ACC/AHA) Stage D), relying on circulation aidsor waiting for heart transplantation.
9. proposed implantation of heart failure device such as cardiac resynchronizationtherapy/cardiac resynchronization therapy defibrillator (CRT/CRT-D) or cardiaccontractility modulation (CCM).
10. untreated severe coronary artery stenosis requiring coronary revascularization, orother cardiac macrovascular disease requiring surgery.
11. hypertrophic cardiomyopathy, restrictive cardiomyopathy, constrictive pericarditis, orstructural heart disease leading to heart failure other than dilated heart disease.
12. severe pulmonary hypertension ( PASP >70 mmHg), or pulmonary hypertension associatedwith no-left heart disease, e.g. pulmonary arterial hypertension (PAH) etc.
13. acute myocardial infarction within 4 weeks before operation.
14. acute cerebrovascular accident within 30 days before operation.
15. acute peptic ulcer or upper gastrointestinal bleeding within 3 months beforeoperation.
16. uncontrolled hyperthyroidism.
17. uncontrolled autoimmune connective tissue diseases especially Behcet's disease andsystemic lupus erythematosus (SLE).
18. amyloidosis.
19. severe infections, septicaemia.
20. severe hepatic insufficiency, e.g. acute severe hepatitis, decompensated cirrhosis (Child-Pugh class C)
21. severe renal insufficiency ( chronic kidney disease (CKD) stage 5: estimatedglomerular filtration rate (eGFR) < 15 ml/min or dialysis).
22. hypotensive state, shock ( systolic blood pressure < 90mmHg or mean arterial pressure <70 mmHg with tissue hypoperfusion and urine output < 30 ml/h).
23. uncontrolled diseases of the haematological system: acute gastrointestinal bleeding,intracranial haemorrhage or haemorrhage from other organs, acute pulmonary embolism ordeep vein thrombosis, congenital or acquired haemorrhagic disease such as haemophilia,anaphylactic purpura and acute leukaemia, severe abnormalities in haematologicalparameters such as platelet count <20*10^9/L and international normalized ratio (INR) >3.
24. contraindication for TEE, e.g. oesophageal constriction, oesophageal tumour,oesophageal fistula, oesophageal varices, cervical vertebral instability, etc.
25. contraindication for intravenous anaesthesia, e.g. allergy to anaesthetics.
26. pregnancy or breastfeeding.
27. The patient does not sign an informed consent form.
28. expected survival less than 1 year.
29. The patient with poor compliance is not thought to complete follow-up visits.
30. The patient is participating in an experimental drug or other device study with anincomplete primary endpoint, or the patient is participating in an unfinishedexperimental drug or other device study that would clinically interfere with our studyendpoints.
31. Due to other reasons the patient is not suitable for enrollment assessed by theresearcher.