To investigate to assess the severity of mitral regurgitation by multimodality imaging.

In the single-center and open-label study, the researcher will compare the changes of ultrasonic cardiography (UCG) parameters when patients in fasting, anaesthesia and rehydration firstly. The aims are to clarify the effect of fasting and anaesthesia on the assessment of mitral regurgitation (MR) severity and the corrective effect of intravenous rehydration. The researcher then will investigate the correlation and consistency of multimodality imaging in assessing the severity of mitral regurgitation. The aim is to acquire more accurate, objective and reproducible parameters, to provide new solution for the precise assessment of MR severity and to guide the selection of clinical treatment and timing.

Inclusion Criteria:

1. age ≥ 18 years old
2. all-caused moderate or severe MR assessed by Trans-Thoracic Echocardiography (TTE) : 1) EROA ≥0.3cm^2; 2) RVol ≥45ml
3. The patient has signed an informed consent form.

Exclusion Criteria:

1. unstable angina, acute myocardial infarction and surgical history of coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) within 3 months before recruit
2. acute heart failure or acute worsening of chronic heart failure requiring vasoactive drug therapy
3. severe infections, septicaemia
4. severe hepatic insufficiency ( Child-Pugh class C)
5. severe renal insufficiency ( chronic kidney disease (CKD) stage 5: estimated glomerular filtration rate (eGFR) <15ml/min or dialysis)
6. hypotensive state, shock ( systolic blood pressure <90mmHg or mean arterial pressure <70mmHg with tissue hypoperfusion and urine output <30ml/h)
7. uncontrolled diseases of the haematological system: acute gastrointestinal bleeding, intracranial haemorrhage or haemorrhage from other organs, acute pulmonary embolism or deep vein thrombosis, congenital or acquired haemorrhagic disease such as haemophilia, anaphylactic purpura and acute leukaemia, severe abnormalities in haematological parameters such as platelet count <20*10^9/l and international normalized ratio (INR) >3
8. contraindication for Trans-Esophageal Echocardiography (TEE) such as oesophageal constriction, oesophageal tumour, oesophageal fistula, oesophageal varices, cervical vertebral instability
9. contraindication for CMR such as metal foreign matter in the body, claustrophobia
10. contraindication for intravenous anaesthesia such as allergy to anaesthetics
11. pregnancy or breastfeeding
12. The patient does not sign an informed consent form.
13. Due to other reasons the patient is not suitable for enrollment assessed by the researcher.