Heart Disease in Pregnancy - The Risks
Dateline: 07/26/98
Pregnancy is one of the physiological conditions that places a considerable burden on the heart, forcing it to work harder for a significantly long period - nine months. While a normal heart is quite capable of taking this extra workload right in its stride, a diseased one may not be able to cope. Different kinds of heart disease may cause different problems during pregnancy. In this series of articles I plan to discuss this topic in depth.
Risk during pregnancy to the mother with heart disease
Pregnancy poses an inordinately high risk for mothers with heart disease in conditions where blood flow into the lungs is obstructed. The block may be at the
- inlet to the lungs, the pulmonary valve e.g. pulmonary stenosis
- outlet from the lungs, the mitral valve e.g. mitral stenosis
In both of these situations, blood flow into the lungs does not keep pace with the increased flow to the rest of the body imposed by the pregnant state.
The diseases which are associated with the highest risk to the mother during pregnancy are:
- Eisenmenger syndrome (severe pulmonary hypertension as a consequence of a long standing left to right shunt lesion like ASD, VSD or PDA) in which the maternal mortality risk is as high as 30-50%
- Primary pulmonary hypertension, a disease of unknown cause that increases the resistance to blood flow in the lungs
- Cor pulmonale, a disease of lung blood vessels secondary to smoking or other lung fibrosing illnesses
- Pulmonary venous occlusive diseases which block the outflow of blood from the lungs back to the heart
Among the congenital heart diseases, Tetralogy of Fallot carries a risk of 4 to 20% of mortality in the mother. Atrial septal defects are perhaps the safest of all birth defects. Even with more the serious conditions, obsessional care can reduce the risks considerably.
Rheumatic heart valve disease is another risk, with patients having mitral stenosis having a 1% chance of developing pulmonary edema during pregnancy. Other diseases like Ehlers Danlos syndrome (a disorder of the connective tissue of the body resulting in loose skin and lax joints) can cause a higher risk of bleeding from major blood vessels that might rupture during pregnancy.
Risk to the fetus during pregnancy with heart disease
In mothers with rheumatic heart valve disease, the fetus develops almost normally. The only difference noted is a mild growth retardation, with babies being lighter by around 200 grams.
In mothers with congenital heart disease too, pregnancy is almost normal in diseases without cyanosis. However, in cyanotic mothers, many problems like severe growth retardation and higher abortion rates arise. Because the maternal blood has a very low oxygen content, there is a lower oxygen exchange across the placenta, and the fetus gets lesser oxygen than normal. As a result, the fetus dies or is delivered prematurely. The situation is however reversed after surgical correction is done.
Coarctation of the aorta is another special condition, in which fetal loss is higher than normal (13%) as a result of lower blood flow to the placenta due to the narrowed aorta.
Will the fetus also develop congenital heart disease ?
A question most parents who themselves have birth defects will ask their doctor is "Will my child also have CHD ?" The risk of congenital heart disease in such pregnancies is 2-4 %, which is twice the incidence of heart disease in the general population. This risk also varies with different conditions. For instance, it is 3% in parents with Tetralogy of Fallot but almost 18% in those with Aortic Stenosis.
Another interesting fact is that such defects are concordant - that is, the defect in the child is usually the same one as of the mother. Importantly, if the mother's defect was one caused by an external factor - for example, by exposure to a drug, or an infection with German measles during gestation - then the fetus of such a person would have a risk of birth defects SIMILAR to the general population only.
In the next article, we will see how congenital heart disease affects the pregnancy.
And don't forget. You can post your comments on this article on the Heart Disease Bulletin Board or discuss it in the Chat Room.
You can also review articles in the following interest areas dealing with heart disease:
- Minimally Invasive Heart Surgery
- MICAS website
- Fetal Heart Surgery
- Congenital Heart Disease
- Heart Disease in Women
- Post operative care after heart surgery
Comments ? Feel free to air your views on this article. You can
- send me e-mail
- post on the heart disease bulletin board
- chat about it in the heart disease chat room.
I'll collect and compile interesting postings into a future article, of course with due credit to the authors. So go ahead and speak up your mind !
Let me know:
How did you like this week's article ? Please write to me with suggestions, comments or criticism.
But do write !
Take some time to browse through:
What's new ?
And if you would like to read more about the latest breaking stories on heart disease, visit "The
Newsdesk" ... it's updated every week, and has a lot more exciting stuff.
Suggested Reading on Heart Disease:
If you're looking for some good books to read on heart disease prevention and treatment, drop into
the bookstore. You can order online right there.
