Your Family Physician

Introduction

Background

Peripartum cardiomyopathy (PPCM) is a dilated cardiomyopathy of uncertain etiology that is defined as (1) development of cardiac failure in the last month of pregnancy or within 5 months after delivery, (2) absence of a demonstrable cause for the cardiac failure, (3) absence of demonstrable heart disease before the last month of pregnancy, and (4) documented systolic dysfunction. This documentation helps avoid misdiagnosing other conditions that present with pulmonary edema in pregnancy, such as diastolic dysfunction from preeclampsia and other disorders listed in Differentials.

PPCM is more common in multiparous women. It has been reported more often in twin gestations and in women with preeclampsia, but both of these conditions are associated with a lower serum oncotic pressure that can predispose to noncardiogenic pulmonary edema in the setting of other stressors.

Pathophysiology

The exact cause is unknown. Proposed etiologies including low selenium levels, various viral infections, and autoantibodies have been implicated. More recent evidence makes myocarditis less likely.

Frequency

United States

Reports estimating incidence in the United States vary and include 1 case per 1300, 4000, and up to 15,000 live births.

75% are diagnosed within the first month postpartum and 45% present in the first week. When suspected, one must establish the diagnosis rapidly.¹

International

The prevalence is reported to be 1 case per 6000 live births in Japan, 1 case per 1000 live births in South Africa, and 1 case per 350-400 live births in Haiti. A high prevalence in Nigeria is caused by the tradition of ingesting kanwa (dried lake salt) while lying on heated mud beds twice a day for 40 days postpartum. The high salt intake leads to volume overload.

Mortality/Morbidity

Mortality figures from multiple small series have ranged from 7-50%, with half of the deaths occurring within 3 months of delivery. The usual causes are progressive heart failure, arrhythmia, or thromboembolism. The mortality rate related to embolic events has been reported to be as much as 30%.

• Acutely, maternal hypoxia can cause fetal distress.
• Thromboembolic phenomenon may complicate PPCM due to the hypercoagulability of pregnancy and either a low-flow state predisposing to venous thrombosis or arterial embolism originating from a severely dilated left ventricle or fibrillating left atrium. When PPCM is diagnosed, antepartum anticoagulation with subcutaneous heparin should be instituted and continued until 6 weeks postpartum. For reasons described in the Treatment and Medication sections, unfractionated heparin offers some advantages over low molecular weight heparin during the antepartum period.

Race

PPCM has been reported in white, Chinese, Korean, and Japanese women. Based on case series, most cases occur in African American women from the southern United States.

Sex

PPCM is unique to pregnant women of all reproductive ages.

Age

Initially thought to be more common in women older than 30 years, PPCM has been reported across a wide range of age groups. The past bias toward older women may be related to the fact that this group has a higher prevalence of undiagnosed conditions, such as thyrotoxicosis, mitral stenosis, or hypertension, which, in combination with some complication of pregnancy and the physiologic alterations of pregnancy, leads to pulmonary edema.

Clinical

History

Normal pregnancy

• Mild dyspnea upon exertion is common.
• Many presenting complaints observed in patients with cardiac disease occur during a normal pregnancy.
• Dyspnea, dizziness, orthopnea, and decreased exercise capacity often are normal symptoms in pregnant women.
• The classic dyspnea of pregnancy is described as an inability to get enough air in, to get a good deep breath, or both, and it is thought to be due to the progesterone-mediated hyperventilation.

Peripartum cardiomyopathy

• Symptoms are the same as in patients with systolic dysfunction who are not pregnant.
• New or rapid onset of the following symptoms requires prompt evaluation: cough, orthopnea, paroxysmal nocturnal dyspnea, fatigue, palpitations, hemoptysis, chest pain, and abdominal pain.

Physical

Normal pregnancy

• Due to the increase of endogenous progestins, respiratory tidal volume is increased and patients have a tendency to hyperventilate. However, the rate of respiration should be normal.
• Normal pregnancy is characterized by an exaggerated X and Y descent of the jugular venous waveform, but the jugular venous pressure should be normal.
• Cardiac auscultation reveals a systolic ejection murmur at the lower left sternal edge, over the pulmonary area, or both in 96% of women. This pulmonic arterial flow murmur tends to become quieter during inspiration. Diastolic murmurs warrant further evaluation. The S₁ may be exaggerated, and the S₂ split may be more prominent due to increased right-sided flow. While an S₃ has been described as a normal finding in pregnancy, the authors have not found that to be the case in busy clinical practices at women's hospitals that see approximately 14,000 deliveries a year.
• Peripheral edema occurs in approximately one third of healthy gravid women. However, be alert to sudden changes in swelling late in pregnancy, which can be abnormal and should be investigated.

Peripartum cardiomyopathy

• Signs of heart failure are the same as in patients with systolic dysfunction who are not pregnant.
• Tachycardia
• Decreased pulse oximetry (should be ³ 97% at sea level)
• Blood pressure may be normal. Physical findings of PPCM include elevated jugular venous pressure, cardiomegaly, third heart sound, loud pulmonic component of the second heart sound, mitral and/or tricuspid regurgitation, pulmonary rales, worsening of peripheral edema, ascites, arrhythmias, embolic phenomenon, and hepatomegaly.

Elevated blood pressures (systolic >140 mm Hg and/or diastolic >90 mm Hg) and hyperreflexia with clonus suggest preeclampsia.

Causes

• The cause of PPCM is unknown, but the usual causes of systolic dysfunction and pulmonary edema should be excluded.
• Many nutritional disorders have been suggested as causes, but other than salt overload, none has been validated by epidemiological studies.
• An increased prevalence of myocarditis has been found in case series and in a small case-control study. Abnormal myocardial biopsy findings were associated with a worse long-term prognosis for recovery. More recent data have found a similar incidence of myocarditis in women with PPCM, when compared to those with the idiopathic type. However, a study that found myocarditis in 62% of 44 women with PPCM found that the finding did not correlate with survival.
• Recent studies have found lower levels of selenium in patients with PPCM.
• Autoantibodies against myocardial proteins have been identified in patients with PPCM but not in those with idiopathic cardiomyopathy.
• Case reports and anecdotal experience have documented ejection fractions as low as 10-15% in patients with severe preeclampsia, with subsequent normalization of echocardiograms within 3-6 months. Preeclampsia has been listed as a risk factor, but it may be the cause in some cases. Noncardiogenic pulmonary edema has many causes, all of which must be considered.²
• A study in 2005 found that 8 of 26 patients had parvovirus B19, human herpes virus 6, Epstein-Barr virus, and human cytomegalovirus detected after molecular analysis of myocardial biopsy specimens.³

Source : http://emedicine.medscape.com/article/153153-overview