Congenital mitral insufficiency is one of the most common valvular diseases in the pediatric population worldwide, carrying a high morbidity and mortality risk if not treated immediately and properly. Given that mitral replacement likely increased risk of cardiac dysfunction and mitral reoperation, mitral repair is the currently preferred surgical strategy in the majority of pediatric patients with mitral insufficiency. Unfortunately, previous evidences demonstrated the long-term hemodynamic alteration in response to significant mitral regurgitant might lead to a reversible or irreversible pulmonary vascular remodeling regardless of concomitant other cardiac malformations, which is associated with increased risk of morbidity and mortality following the surgery. Currently available researches mainly focused the association of pulmonary vascular pressures with risk of mortality and morbidity on adult rheumatic or degenerative mitral insufficiency; however, knowledge is still lacking regarding pediatric population with congenital mitral insufficiency. The investigator wil assess the relationship between baseline sPAP and risk of operative morbidity and mortality.

Inclusion Criteria:

• evidence of normal or preserved left ventricular systolic function (defined as left ventricular ejection fraction [LVEF] >50%);
• native mitral regurgitation of grade moderate or greater;
• with or without systemic-to-pulmonary shunting necessitating concomitant surgical repairs, regardless of pulmonary arterial pressure or pulmonary artery wedge pressure.

Exclusion Criteria:

• functional single ventricle;
• rheumatic mitral diseases;
• Eisenmenger syndrome;
• aortopathy, transposition of the great arteries, obstructions of ventricular outflow tract, malignant arrhythmias, cardiomyopathy, microbiological identification of infective endocarditis;
• a history of pericardiotomy or intervention therapy.

The infants and young children aged 5 months to 15 years are eligible for enrolment in this study if they had echocardiography confirmed mitral insufficiency.