Cardiac disease in pregnancy and dilated cardiomyopathy

Overview
Patients with pre-existing cardiomyopathies such as dilated cardiomyopathy and hypertrophic cardiomyopathy, often have significant difficulty dealing with the physiologic and hemodynamic changes that occur during pregnancy, labor, and delivery. In addition to these patients, there is a subset of patients who will develop peripartum cardiomyopathy.

Incidence
Currently, DCM is responsible for "approximately 10,000 deaths and 46,000 hospital stays each year in the United States and is the most common indication for cardiac transplantation."

Cause
The cause often remains unknown, in up to 50% of cases.

Reasons why Women with Dilated Cardiomyopathy are Advised to Avoid Pregnancy

 * Dilated cardiomyopathy has been associated with A-type lamin gene defects, which are associated with a high rate of heart failure and life-threatening arrhythmias, as predicted by NYHA functional class
 * The increase in intravascular volume and cardiac output during pregnancy leads to a greater risk for complications in women with dilated cardiomyopathy, especially in the 3rd trimester
 * A history of cardiac events including previous episodes of heart failure, atrial fibrillation or atrial flutter, transient ischemic attack, or a history of cardiac events before pregnancy is predictive of negative pregnancy-related cardiac outcomes

Management of Heart Failure
The following should be considered when managing heart failure during pregnancy:


 * Goals are similar to non-pregnant patients, including continuation of chronic therapies (with a few exceptions, including ACE inhibitors, angiotensin receptor blockers, and aldosterone antagonists).
 * Beta-blockers can and should be continued through pregnancy.
 * Vasodilator therapy can be safely achieved with amlodipine and hydralazine.
 * Sodium restriction and digoxin can both be used during pregnancy.
 * In the setting of acute decompansation, intravenous diuretics, vasodilators, and monitoring with right heart cathterization are all acceptable.

Management during Labor & Delivery
Finally, the following should be considered during labor and delivery:
 * Multi-disciplinary approach is crucial.
 * Careful maternal continuous monitoring should be employed, including EKG monitoring, non-invasive blood pressure monitoring, and right heart catheterization/arterial line monitoring if necessary.
 * No official recommendation on timing of delivery is established; coordination between the obstetrician and cardiologist is necessary to deem what is safest for the patient.
 * Vaginal delivery generally poses less cardiovascular risk than cesarian section (less blood loss).
 * Induction of labor with an unfavorable cervix should be avoided; induction with a favorable cervix can be achieved with oxytocin and artificial rupture of membranes.
 * Epidural anesthesia, can produce changes in preload and afterload that can be advantageous in the setting of reduced ventricular function, and should be considered along with intravenous opiates to provide analgesia and reduce the hemodynamic demands that accompany significant pain.
 * When in labor, the patient should be placed in a left lateral decubitus position to avoid IVC compression by the gravid uterus, and the first stage of labor should occur without maternal assistance to avoid the hemodynamic effects of the valsalva maneuver.
 * The second stage of labor can be shortened via assistance with low forceps or by vacuum extraction as needed.

Related Chapter
This section will primarily focus on dilated cardiomyopathy (DCM) in pregnancy. For a more detailed discussion of dilated cardiomyopathy, click here.