What is peripartum cardiomyopathy?
Peripartum cardiomyopathy (PPCM), also known as postpartum cardiomyopathy, is an uncommon form of heart failure that happens during the last month of pregnancy or up to five months after giving birth. Cardiomyopathy literally means heart muscle disease.
PPCM is a dilated form of the condition, which means the heart chambers enlarge and the muscle weakens. This causes a decrease in the percentage of blood ejected from the left ventricle of the heart with each contraction. That leads to less blood flow and the heart is no longer able to meet the demands of the body's organs for oxygen, affecting the lungs, liver, and other body systems.
PPCM is rare in the United States, Canada, and Europe. About 1,000 to 1,300 women develop the condition in the U.S. each year. In some countries, PPCM is much more common and may be related to differences in diet, lifestyle, other medical conditions or genetics.
How is it diagnosed?
PPCM may be difficult to detect because symptoms of heart failure can mimic those of third trimester pregnancy, such as swelling in the feet and legs, and some shortness of breath. More extreme cases feature severe shortness of breath and prolonged swelling after delivery.
During a physical exam, doctors will look for signs of fluid in the lungs. A stethoscope will be used to listen for lung crackles, a rapid heart rate, or abnormal heart sounds. An echocardiogram can detect the cardiomyopathy by showing the diminished functioning of the heart.
PPCM is diagnosed when the following three criteria are met:
- Heart failure develops in the last month of pregnancy or within 5 months of delivery.
- Heart pumping function is reduced, with an ejection fraction (EF) less than 45% (typically measured by an echocardiogram). EF is how much blood the left ventricle pumps out with each contraction. A normal EF can be between 55 and 70.
- No other cause for heart failure with reduced EF can be found.
Laboratory blood tests are a standard part of the evaluation. This includes tests to assess kidney, liver and thyroid function; tests to assess electrolytes, including sodium and potassium; and a complete blood count to look for anemia or evidence of infection. In addition, markers of cardiac injury and stress can be used to assess level of risk.
Symptoms of the condition include:
- Feeling of heart racing or skipping beats (palpitations)
- Increased nighttime urination (nocturia)
- Shortness of breath with activity and when lying flat
- Swelling of the ankles
- Swollen neck veins
- Low blood pressure, or it may drop when standing up.
The severity of symptoms in patients with PPCM can be classified by the New York Heart Association system:
- Class I - Disease with no symptoms
- Class II - Mild symptoms/effect on function or symptoms only with extreme exertion
- Class III - Symptoms with minimal exertion
- Class IV - Symptoms at rest
What are the causes?
The underlying cause is unclear. Heart biopsies in some cases show women have inflammation in the heart muscle. This may be because of prior viral illness or abnormal immune response. Other potential causes include poor nutrition, coronary artery spasm, small-vessel disease, and defective antioxidant defenses. Genetics may also play a role.
Initially thought to be more common in women older than 30, PPCM has since been reported across a wide range of age groups. Risk factors include:
- History of cardiac disorders, such as myocarditis (inflammation of the heart muscle)
- Use of certain medications
- Multiple pregnancies
- African-American descent
- Poor nourishment
How can PPCM be treated?
The objective of peripartum cardiomyopathy treatment is to keep extra fluid from collecting in the lungs and to help the heart recover as fully as possible. Many women recover normal heart function or stabilize on medicines. Some progress to severe heart failure requiring mechanical support or heart transplantation.
There are several classes of medications a physician can prescribe to treat symptoms, with variations that are safer for women who are breastfeeding.
- Angiotensin converting enzyme, or ACE, inhibitors – Help the heart work more efficiently
- Beta blockers – Cause the heart to beat more slowly so it has recovery time
- Diuretics – Reduce fluid retention
- Digitalis – Derived from the foxglove plant, it has been used for more than 200 years to treat heart failure. Digitalis strengthens the pumping ability of the heart
- Anticoagulants – To help thin the blood. Patients with PPCM are at increased risk of developing blood clots, especially if the EF is very low.
Doctors may recommend a low-salt diet, fluid restrictions, or daily weighing. A weight gain of 3 to 4 pounds or more over a day or two may signal a fluid buildup.
Women who smoke and drink alcohol will be advised to stop, since these habits may make the symptoms worse.
A heart biopsy may help determine if the underlying cause of cardiomyopathy is a heart muscle infection (myocarditis). However, this procedure is uncommon.
How can women minimize their risk?
To develop and maintain a strong heart, women should avoid cigarettes and alcohol, eat a well-balanced diet and get regular exercise. Women who develop peripartum cardiomyopathy are at high risk of developing the same condition with future pregnancies.
Investigations are underway to understand the cause of PPCM and to develop new treatments. Treatments that alter the immune system such as intravenous γ-globulin and immunoabsorption have been tried but are not proven. Investigators also have focused on the role of prolactin in PPCM. Prolactin is a hormone released from the pituitary gland late in pregnancy and after delivery that stimulates breast milk production. Prolactin, however, may have adverse effects on the heart muscle by limiting its blood supply and causing cell death. Bromocryptine is a medication that inhibits the pituitary secretion of prolactin. Early studies suggest it helps treat PPCM, but more research is needed.