Uri Elkayam, professor of medicine in the Keck School of Medicine of USC.

Photo by Irene Fertik

That is, until now.

Drawing on the vast patient base of LAC+USC Medical Center and its high-risk obstetrics/cardiology clinic, a team of USC physicians has conducted the most extensive study to date on pregnant women with valvular heart disease. The study was published in the March issue of the Journal of the American College of Cardiology.

Getting enough data to describe the problems involved in pregnancies among women with valvular heart disease can be tough because the conditions are fairly rare.

“Most people don’t see that many of these cases,” said cardiologist Uri Elkayam, professor of medicine and the study’s principal investigator. “Because of our local obstetric population, over the years we’ve been able to accumulate experience with patients that others do not have.”

Investigators believe the results of the study will help physicians to assess the risk of pregnancy and provide the appropriate advice to patients with valvular heart disease before the patients get pregnant.

When doctors talk about valvular heart disease, they often are referring to problems with the mitral, aortic or pulmonic valves.

These valves allow blood to pump efficiently into and out of the chambers of the heart.

For this study, physicians on the faculty of the Keck School of Medicine of USC followed wo men with stenosis of the mitral, aortic or pulmonic valves – a condition in which the valve is narrowed or obstructed. Some women in the study had mitral regurgitation, which happens when the valve does not completely close.

Physicians looked at 66 pregnancies in 64 women with valvular heart disease, comparing them to another 66 normal pregnant wo men also followed at LAC+USC Medical Center.

Overall, the re searchers found that women with valvular problems were more likely than other women to have congestive heart failure and arrhythmias, and were more likely to need to start taking heart medications (or increase the dosage of medications they were already taking) or to be hospitalized during pregnancy.

These valvular diseases also affected fetal health, Elkayam said. Affected women were more likely to deliver their babies prematurely, and their fetuses were more likely not to grow properly and to be born with low birth weight.

But the difficulties were not seen equally among all women with valve problems, Elkayam said.

Women with mild cases of mitral and aortic stenosis tended to do just as well as normal, healthy women with their pregnancies – and their babies were just as healthy.

Women with moderate and severe cases, though, had more difficult pregnancies. In the case of both mitral and aortic stenosis, the physicians found a clear relationship between severity of the disease and the problems women and fetuses suffered during pregnancy.

Some women even suffered from pulmonary edema (accumulation of fluid in the lungs) several days after giving birth.

Women with pulmonic stenosis, however, did not appear to suffer increased complications.

Problems such as congestive heart failure are not surprising in pregnant women with valve problems, the researchers said, be cause of the normal increase in the volume of blood moving through the cardiovascular system during pregnancy.

When it comes to the child, compromised blood flow due to valvular problems and decreased blood flow to the uterus may keep fetuses from growing properly in the womb.

Heart medications given to the mother might also play a role, and arrhythmias (irregular heartbeat) may cause some fetal distress.

“The results of this study indicate the need for close maternal follow-up and fetal surveillance in pregnant patients with moderate or severe aortic or mitral stenosis,” the researchers wrote.

Ideally, patients should have valvular stenosis repaired before pregnancy, if possible.

Although women with serious valvular disease should consider balloon valvuloplasty during pregnancy to prevent complications, the benefits of the procedure should be carefully weighed against its risks, the researchers concluded.

Mitral stenosis affects about 2 of every 10,000 people and is caused by rheumatic fever, while aortic stenosis affects about 5 of every 10,000 people and is congenital in most cases.

The program for mitral valve balloon valvuloplasty at the division of cardiology in the Keck School, under the leadership of Anil Mehra, assistant professor of clinical medicine, is one of the most experienced in the country.

In addition to Elkayam, the Keck School team included Afshan Hameed and T. Murphy Goodwin from the department of obstetrics and gynecology, and Ilyas Karaalp, Padmini Tummula, Omar Wani, Menahem Canetti, Mohammed Akhter and Natalia Zapadinsky from the department of medicine’s cardiology division.