Cardiovascular disease in pregnancy
Cardiovascular disease in pregnancy: Excerpt from Handbook of Diseases
Cardiovascular disease ranks fourth (after infection, toxemia, and hemorrhage) among the leading causes of maternal death. The physiologic stress of pregnancy and delivery is sometimes more than a compromised heart can tolerate and commonly leads to maternal and fetal death.
Between 1% and 2% of pregnant women have cardiac disease, but the incidence is rising because medical treatment today allows more females with rheumatic heart disease and congenital defects to reach childbearing age.
With careful management, the prognosis for the pregnant patient with cardiovascular disease is good. Decompensation is the leading cause of maternal death. Infant mortality increases with decompensation because uterine congestion, insufficient oxygenation, and the elevated carbon dioxide content of the blood not only compromise the fetus but may also cause premature labor and delivery.
Causes
Rheumatic heart disease is present in more than 80% of patients who develop cardiovascular complications. In the rest, these complications stem from congenital defects (10% to 15%) and coronary artery disease (2%).
The diseased heart is sometimes unable to meet the normal demands of pregnancy: a 25% increase in cardiac output, a 40% to 50% increase in plasma volume, increased oxygen requirements, retention of salt and water, weight gain, and alterations in hemodynamics during delivery. This physiologic stress commonly leads to the heart’s failure to maintain adequate circulation (decompensation).
The degree of decompensation depends on the patient’s age, the duration of cardiac disease, and the functional capacity of the heart at the outset of pregnancy.
Signs and symptoms
Typical signs and symptoms of cardiovascular disease in pregnancy include neck vein distention, diastolic murmurs, moist basilar pulmonary crackles, cardiac enlargement (discernible on percussion or as a cardiac shadow on a chest X-ray), and cardiac arrhythmias (other than sinus or paroxysmal atrial tachycardia). Other characteristic abnormalities include cyanosis, pericardial friction rub, pulse delay, and alternating pulse.
Clinical tip Mitral valve prolapse is most common. Its accompanying signs and symptoms include rapid heart rate, palpitations, and mitral insufficiency or murmur. Echocardiography confirms the condition.
Decompensation may develop suddenly or gradually, with persistent crackles at the lung bases. As it progresses, edema, increasing exertional dyspnea, palpitations, a smothering sensation, and hemoptysis may occur.
Diagnosis
A diastolic murmur, cardiac enlargement, a systolic murmur of grade III or IV intensity, and severe arrhythmia suggest cardiovascular disease.
Determination of the extent and cause of the disease may necessitate electrocardiography, echocardiography (for valvular disorders such as rheumatic heart disease), or phonocardiography. X-rays show cardiac enlargement and pulmonary congestion. Cardiac catheterization should be postponed until after delivery, unless surgery is necessary.
Treatment
Specific treatments vary before, during, and after delivery.
Before delivery
The goal of antepartum management is to prevent complications and minimize the strain on the mother’s heart, primarily through rest. This may require periodic hospitalization for patients with moderate cardiac dysfunction or with symptoms of decompensation, toxemia, or infection. Older women or those with previous decompensation may require hospitalization and bed rest throughout the pregnancy.
Drug therapy is usually necessary and should include the safest drug in the lowest possible dose to minimize harmful effects to the fetus. Diuretics and drugs that increase blood pressure, blood volume, or cardiac output should be used with extreme caution.
If an anticoagulant is needed, heparin is the drug of choice. A cardiac glycoside and an antiarrhythmic are typically required. The prophylactic use of antibiotics is reserved for patients who are susceptible to endocarditis.
A therapeutic abortion may be considered for patients with severe cardiac dysfunction, especially if decompensation occurs during the first trimester. Patients hospitalized with heart failure are usually treated with a cardiac glycoside, oxygen, rest, sedation, and a diuretic; intake of sodium and fluids is also restricted. Patients whose symptoms of heart failure don’t improve after treatment with bed rest and a cardiac glycoside may require cardiac surgery, such as valvotomy and commissurotomy.
During delivery
The patient in labor may require oxygen and an analgesic, such as meperidine or morphine, for pain relief and apprehension without undue depression of the fetus or herself. Depending on which procedure promises to be less stressful for the patient’s heart, delivery may be vaginal or by cesarean section. Operative vaginal delivery (for example, with forceps) is usually preferable to avoid the blood pressure changes that occur with pushing.
After delivery
Bed rest and medications already instituted should continue for at least 1 week after delivery because of a high incidence of decompensation, cardiovascular collapse, and maternal death during the early puerperal period. These complications may result from the sudden release of intra-abdominal pressure at delivery and the mobilization of extracellular fluid for excretion, which increase the strain on the heart, especially if excessive interstitial fluid has accumulated.
Special considerations
❑ During pregnancy, stress the importance of rest and weight control to decrease the strain on the heart.
❑ Encourage the patient to take supplementary folic acid and iron, as ordered, to prevent anemia.
❑ During labor, watch for indications of decompensation, such as dyspnea and palpitations. Monitor pulse rate, respirations, and blood pressure. Auscultate for crackles every 30 minutes during the first phase of labor and every 10 minutes during the active and transition phases. Check carefully for edema and cyanosis, and assess intake and output. Administer oxygen for respiratory difficulty.
❑ Use electronic fetal monitoring to watch for the earliest signs of fetal distress.
❑ Keep the patient in a semirecumbent position. Limit her efforts to bear down during labor, which significantly raise blood pressure and stress the heart.
❑ After delivery, provide reassurance, and encourage the patient to adhere to her treatment regimen. Emphasize the need to rest during her hospital stay.
Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
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