Mitral valve replacement
The mitral valve lies between the left atrium and the left ventricle. If the mitral valve becomes narrowed (stenosed), blood flow can be severely reduced and the valve may need to be replaced.


How to interpret the survival funnel plots

These graphs show the national average survival after specific procedures for treating congenital heart disease. The national average is shown as a horizontal grey line. Two control limits are shown; a warning limit (Green line, 98%) and an alert limit ( Red line 99.5%). Unit performances are shown as identifiable coloured symbols. If a unit's symbol is above the green line then the performance is no different from the national average. If a unit’s survival rate is below the warning limit, their performance will be closely monitored in subsequent years. If a unit’s survival rate is below the alert limit, an investigation into possible reasons and remedial actions will be launched by the appropriate professional and regulatory bodies.