ASHEVILLE, N.C. — Focus on the woman's health in those rare cases of peripartum cardiomyopathy, said Thomas S. Ivester, M.D., at the Southern Obstetric and Gynecologic Seminar. “Maternal health is of paramount importance in this situation,” Dr. Ivester, of the department of maternal-fetal medicine said during the University of North Carolina at Chapel Hill.
Cardiomyopathy is an infrequent but potentially fatal complication of pregnancy. The mortality rate is 0.4 per 100,000 live births. Risk factors during pregnancy include multiparity, advanced age, African American race, and preeclampsia.
Care of critically ill pregnant women requires a team-based approach, with good communication among caregivers and specialists. Obstetricians can serve a vital role in educating critical care colleagues about treating pregnant patients who are critically ill.
In particular, “cardiac indices and central venous pressure are notoriously inaccurate in critically ill gravida. This is especially so with preeclampsia,” said Dr. Ivester. Use echocardiography to assess volume or use a P.A. catheter to get a wedge pressure.
Fetal decompensation is frequently a warning sign of subsequent significant maternal decompensation. “Once it's detected, cardiac monitoring of the fetus should probably be ceased until the mom is completely stabilized. Intervention in that scenario is probably ill advised,” said Dr. Ivester.
In patients who have significant hemorrhage or in those who may have suffered some type of hypovolemic insult or have been in shock, dopamine can be used to preserve and enhance renal and placental perfusion. “So a renal dose of dopamine, you can also consider as a placental dose of dopamine,” Dr. Ivester said.
Whenever possible, delivery should be reserved for obstetric indications. Vaginal delivery is preferred, because it is tolerated better by the woman. These patients should have prophylaxis for deep vein thrombosis, which can be accomplished by mechanical or chemical means.
“Close follow-up of any case of peripartum cardiomyopathy is critical,” Dr. Ivester said. He suggests serial echocardiography to evaluate the recovery of left ventricular function. Avoiding subsequent pregnancies until function improves is important, so make sure these patients are on adequate contraception. Earlier ICD implantation or placement on a transplant list should be considered for patients who suffer significant rhythm deterioration or have persistently low ejection fractions.
“Most importantly, … obstetric issues do not disappear with delivery. [The mother] is still an obstetric patient, even when the baby is delivered,” Dr. Ivester said. Peripartum changes can persist in some women for many weeks after delivery, and the obstetrician still has an important role to play in their care, especially in helping to differentiate the changes associated with pregnancy from other conditions.
In a normal pregnancy, blood volume increases 50%–100%. Systemic vascular resistance decreases 20%, and the blood is hypercoagulable. Cardiac output can fluctuate. Respiratory alkalosis may occur. The heart is displaced upward and to the left. The patient will have slight left ventricular hypertrophy and effusion that can be seen on echocardiography. There is frequently a left axis deviation due to these changes. There also may be nonspecific ST segment and T-wave changes.
Profound cardiac changes also occur during labor. Systemic vascular resistance can go up 10%–25% with each contraction. “That's a substantial increase for a patient with a very sick myocardium or those with significant valvular diseases,” Dr. Ivester said. Women in labor will autoinfuse 300–500 cc every time they contract, especially if they are near term. Cardiac output fluctuates as labor progresses. In early labor (<3 cm), cardiac output goes up about 17%. In the second stage of labor (> 8 cm), cardiac output increases at least 34%.