Q. Illustrate Mitral Stenosis and Pregnancy ?
Since mitral stenosis is often seen in young women, it is not uncommon to see young women with pregnancy complicated by mitral stenosis. Unlike mitral regurgitation, it is poorly tolerated. During pregnancy cardiac output, blood volume and heart rate-all increase. This leads to increased flow during shortened diastolic period and pressure gradients increase across mitral valve for any mitral valve area. Hence patients with even moderate mitral stenosis become quite symptomatic during pregnancy. These young women require proper counselling before marriage and conception but unfortunately due to social conditions this is never effective. Mild to moderate mitral stenosis (MVA < 1.3sq, cm) may safely sail through pregnancy, but often more sicker patients will end up with problems. It is not uncommon to see a pregnant woman with tight mitral stenosis presenting with pulmonary edema late in pregnancy. If seen in first trimester and the patient has more than mild mitral stenosis it is advisable to terminate the pregnancy and correct valvular lesion. If mitral stenosis at that time is mild to moderate and transvalvular gradients across mitral valve are low, pregnancy may be continued but close medical supervision is needed.
Whenever symptomatic, such patient may be started on beta blockers and small dose of diuretics. These drugs can cause fetal growth retardation and should be given in the smallest doses required. If the patient with tight mitral stenosis is seen later in the pregnancy and is symptomatic, she should be offered balloon valvuloplasty if the valve is suitable. Closed mitral valvotomy and mitral valve replacement carry high risk of fetal wastage and maternal morbidity. However, during balloon valvotomy fetus may be exposed to radiation and proper lead shield has to be used and procedure completed by an expert in shortest possible time avoiding unnecessary fluoroscopic time. Pregnant patients with prosthetic mitral valve or with atrial fibrillation who require oral anticoagulants are usually managed with heparin during 6-12 weeks of pregnancy and again later during the last two weeks. Fetal teratogenecity and maternal valve related complications are least with this approach.