hi and welcome. well RHEUMATIC hart disease frequently damaged the MITRAL valve more than any other valve. the velve serves as a stopper for one way traffic of blood. the destruction of the valve causes it unable to serve as a stopper and the blood leaks from left ventricle to the left atrium when the high pressure left ventricle contracts. this is called MR. thus severe MR causes the blood to go in the left other chamber called the left atrium rather than going to the main artery for the distribution to the body, thus patient feels dizzy . now the left atrium receives blood from the lungs and is in direct communication with the lungs . so the back pressure causes congestion in the lungs and patient feels short of breath esp on exertion. now the right side of the heart is in communication with the lungs also. conngestion in the lungs causes the right side to work harder as right heart pushes blood in the lungs for oxygenation. the two parts of right side of heart has a valve called TRICUSPIDVALVE, just like mitral valve between two chambers of left side of heart, SO the primary damage of mitral is due to RHD and the tricuspid is functional damage due to pressure over load on right side....net result of lung congestion is pulmonary hypertension, which if severe is a bad sign, and ideally mitral valve replacement early can be life saving. you need to see a cardiologist immediately and to discuss possiblity of valve replacement. take care