Heart disease in pregnancy? Cardiology Basics

Heart disease in pregnancy? Cardiology Basics

Changes in blood circulation during pregnancy and labour can adversely affect many of the significant heart diseases. Increase in blood volume and heart rate are the important factors during pregnancy. Increase in blood volume is needed to give enough nutrients and oxygen to the growing baby. Nutrients and oxygen are transferred to the baby through the placenta during pregnancy, though there is no actual mixing of the blood of the baby and mother. In general, obstructive lesions and complex cyanotic congenital heart diseases have high risk in pregnancy.

Obstructive lesions like severe aortic stenosis and mitral stenosis and lesions with severe pulmonary hypertension like Eisenmenger syndrome are poorly tolerated in pregnancy. Regurgitant lesions aortic and mitral regurgitation are better tolerated than stenotic lesions of the heart valves. Peripheral vasodilatation in pregnancy reduces the afterload and ameliorates regurgitant lesions. Increased blood volume and heart rate in pregnancy increases the chance of pulmonary edema in severe mitral stenosis.

Especially high risk is there in coarctation of aorta in which there is a discrete narrowing of a region of the aorta. When there is obstruction, blood pressure in the part of the aorta upstream to the obstruction is high. This can predispose to aortic dissection and even rupture, especially while straining during labour.

World health organization has classified heart diseases into four risk categories with regards to pregnancy. Class I is the very low risk group, class II low to moderate risk and class III high risk. Class IV has extremely high risk and pregnancy has to be avoided.

Class I includes those with mild pulmonary stenosis, small patent ductus arteriosus and mitral valve prolapse. Successfully repaired simple congenital heart disease also come under the low risk category. Isolated atrial and ventricular ectopics also have very low risk.

Class II or low to moderate risk is there for unoperated atrial and ventricular septal defects and most heart rhythm abnormalities. Those who have undergone repair of tetralogy of Fallot also comes under class II. Mild left ventricular dysfunction and hypertrophic cardiomyopathy also have class II risk.

Those with mechanical heart valves, those who have undergone repair of complex congenital heart diseases other than tetralogy of Fallot, unrepaired cyanotic congenital heart disease and conditions in which there is aortic enlargement come under the Class III or high risk category. All complex congenital heart diseases also come under this category.

Class IV or extremely high risk conditions in which pregnancy has to be avoided include severe pulmonary hypertension of any etiology, severe left ventricular dysfunction and those with symptomatic severe mitral stenosis. Symptomatic severe aortic stenosis also comes under class IV. Severe coarctation of aorta and dilatation of aorta are other reasons to avoid pregnancy.

If there is history of peripartum cardiomyopathy in previous pregnancy with residual left ventricular dysfunction, that is also class IV. Peripartum cardiomyopathy has a chance of recurrence in subsequent pregnancy.

These are only general observations regarding the risk of heart disease in pregnancy. There may be significant individual differences in severity and manifestation of the diseases mentioned, which may alter the situation in a given individual. Any woman with heart disease needs full evaluation before planning pregnancy to avoid major problems during pregnancy and labour.