Peripartum cardiomyopathy is a relatively rare but life-threatening disease. A wide variation in incidence rates ranging from 1 per 14851 to 1 per 15,000 live births2 has been reported although the currently accepted incidence is approximately 1 per 3000 to 1 per 4000 live births3. Surprisingly, a recent analysis of maternal mortality in North Carolina reported at the 2003 Annual SOAP meeting found cardiomyopathy to be the leading cause of maternal death in that state4. It is unclear, however, if all these cases met the definition of peripartum cardiomyopathy or if some were related to preexisting heart disease. Identified risk factors for peripartum cardiomyopathy include advanced maternal age, multiparity, obesity, multiple gestation, preeclampsia, chronic hypertension, and black race5.
Based on a recent report from the National Heart, Lung, and Blood Institute, peripartum cardiomyopathy is defined by the presence of four criteria. These include: (1) development of cardiac failure in the last month of pregnancy or within five months of delivery; (2) absence of an identifiable cause for cardiac failure; (3) absence of recognizable heart disease prior to the last month of pregnancy; and (4) left ventricular systolic dysfunction demonstrated by echocardiographic criteria such as depressed ejection fraction3.
The etiology of peripartum cardiomyopathy remains unknown despite much investigation that has focused on identifying a cause. Proposed causes include myocarditis, abnormal immune response to pregnancy, and maladaptive response to the hemodynamic stresses of pregnancy. There is more evidence to support myocarditis or an autoimmune process as the cause of the disease than for other proposed etiologies. Endomyocardial biopsies in women with peripartum cardiomyopathy have demonstrated myocarditis in many patients but biopsy results differ markedly among studies. The highest incidence of myocarditis reported was 76%6 but one of the most recent series found myocarditis in only 8.8% of patients7.
Patients with peripartum cardiomyopathy present with the typical signs and symptoms of left ventricular failure. The majority of cases occur after delivery and the immediate postpartum period. However, when the disease develops during the last month of pregnancy the diagnosis of cardiac failure is difficult to make by signs and symptoms alone since some of those symptoms, such as fatigue, orthopnea, and pedal edema, are common among normal parturients during late pregnancy. Further testing is required to establish the presence of cardiac failure. A chest x-ray consistently demonstrates cardiomegaly and pulmonary edema. Echocardiography confirms ventricular failure with increased left ventricular end-diastolic dimensions and decreased ejection fraction. Once cardiac failure is identified, peripartum cardiomyopathy must be differentiated from other disease processes that lead to heart failure, such as valvular heart disease.
Maternal mortality from peripartum cardiomyopathy in the United States has been reported to be 25-50%8,9. Thromboembolism accounts for approximately 30% of these deaths. Patients who survive the disease have a significantly higher ejection fraction and smaller left ventricular end-diastolic diameter at the time of diagnosis compared with patients who succumb8. Normalization of heart size and resolution of congestive heart failure within 6 months after delivery is also a good prognostic sign with mortality rare among these patients10. The incidence of resolution is unclear, however. An early series reported that 50% of patients experienced resolution10 but a more recent study reported only a 7% incidence of disease regression. The majority of patients in this recent series died, required cardiac transplantation, or experienced continued cardiac impairment11.
Patients with peripartum cardiomyopathy require counseling concerning the risks of subsequent pregnancy. Patients without resolution of their cardiomyopathy are at significant risk for death or exacerbation of the disease10 and should be advised to avoid pregnancy. There is no consensus on how to advise women whose cardiomyopathy has resolved. One of the earliest studies found that 25% of these patients experienced transient exacerbation during subsequent pregnancy10. An echocardiographic study found normal left ventricular function during and after pregnancy in patients who had previously recovered from peripartum cardiomyopathy12. However, in a more recent study, patients who had a return to normal left ventricular function after peripartum cardiomyopathy still demonstrated impaired contractile reserve during a dobuatamine challenge test13. Therefore, should these patients become pregnant, they should be cared for in collaboration with a high-risk obstetric center.
Medical treatment of peripartum cardiomyopathy is similar to that for other dilated cardiomyopathies. Management goals include preload optimization, afterload reduction, and increased contractility. Anticoagulation is also considered in many patients because of the significant risk of thromboembolism. When the patient develops cardiac failure before delivery, some treatment modifications are required. Angiotensin-converting enzyme inhibitors are routinely used for afterload reduction in congestive heart failure. However, these drugs are contraindicated during pregnancy because of adverse fetal effects. Alternative treatments for afterload reduction during pregnancy include amlodipine or a combination of hydralazine and nitroglycerin.
In addition to treatment of the cardiac failure, an obstetric plan of care must be developed when the disease occurs during pregnancy. Collaboration among the obstetrician, cardiologist, and anesthesiologist is essential to optimize care. If the parturient's cardiac status can be stabilized with medical therapy, induction of labor is usually recommended with cesarean section reserved for obstetric indications. However, in parturients who experience acute cardiac decompensation, cesarean delivery may be required because of an inability of the mother to tolerate the prolonged stresses of labor.
Parturients with peripartum cardiomyopathy require special anesthetic care during labor and delivery. Invasive monitoring, including an arterial line and pulmonary artery catheter, should be utilized to assess the patient's hemodynamic status and guide management. The cardiovascular stress of labor and delivery may lead to cardiac decompensation. When that situation occurs, the anesthesiologist may need to infuse vasoactive agents, such as nitroglycerin or nitroprusside for preload and afterload reduction and dopamine, dobutamine or milrinone for inotropic support. Data from the pulmonary artery catheter is essential to determine the appropriate pharmacologic therapy for each patient.
Early administration of labor analgesia to minimize further cardiac stress associated with pain is paramount in the anesthetic management of these patients. Various analgesic techniques provide unique advantages in the hemodynamic management of the parturient while also providing excellent analgesia. By using invasive monitoring data to guide fluid management and titration of vasoactive drugs, the slow induction of epidural analgesia is a safe and effective analgesic technique in parturients with peripartum cardiomyopathy. In fact, the sympathectomy-induced afterload reduction that occurs with epidural anesthesia can contribute to an improvement in myocardial performance in these patients14. Combined spinal-epidural analgesia is another excellent analgesic option. Because the initial analgesia can be accomplished with spinal opioids, hemodynamic stability may be more easily maintained compared to epidural analgesia since sympathetic blockade is avoided. When injection of epidural local anesthetics is required later in labor, slow titration of the drug can provide the benefits of afterload reduction while avoiding sudden drops in blood pressure that would be deleterious. In the most fragile patients, continuous spinal analgesia is an attractive alternative. A continuous spinal catheter technique permits intermittent intrathecal opioid injection for analgesia throughout the first stage of labor. Supplementation with a small dose of intrathecal local anesthetic is sometimes needed to provide adequate analgesia for the second stage of labor and delivery. A significant advantage of this technique is that hemodynamic stability is more easily achieved because a local anesthetic-induced sympathectomy is avoided for the majority or all of the labor process.
If a cesarean delivery is required, a continuous epidural or spinal anesthetic is usually the best anesthetic option. The patient's hemodynamic status is carefully followed and fluid management is guided by data from the invasive monitors while the anesthesia level is slowly raised. A single-shot spinal technique is not recommended because the rapid hemodynamic changes associated with this technique may not be well tolerated in these fragile patients. General anesthesia is sometimes required when cesarean section is required because of nonreassuring fetal status or acute maternal decompensation. Anesthetic drugs with myocardial depressant effects should be avoided. Induction and maintenance with a high-dose opioid technique is often preferred. If this technique is used, remifentanil is a good choice because its short half-life can minimize depressant effects on the neonate. Trained personnel must be available to manage neonatal depression whenever a high-dose opioid anesthetic is utilized.
Regina Fragneto, MD
University of Kentucky
Department of Anesthesiology
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