Cardiovascular disease in pregnancy
Cardiovascular disease in pregnancy: Excerpt from Professional Guide to Diseases (Eighth Edition)
Cardiovascular disease ranks fourth (after infection, pregnancy-induced hypertension, and hemorrhage) among the leading causes of maternal death. The physiologic stress of pregnancy and delivery is often more than a compromised heart can tolerate and often leads to maternal and fetal mortality.
The prognosis for the pregnant patient with cardiovascular disease is good, with careful management. 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 also commonly cause premature labor and delivery.
Causes and incidence
Approximately 1% to 2% of pregnant females have cardiac disease, but the incidence is rising because medical treatment today allows more females with rheumatic heart disease (present in more than 80% of patients who develop cardiovascular complications) and congenital defects (present in 10% to 15% of patients) to reach childbearing age. Coronary artery disease accounts for about 2% of cardiovascular complications.
The diseased heart is sometimes unable to meet the normal demands of pregnancy: 25% increase in cardiac output, 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 often 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 heart’s functional capacity at the pregnancy’s outset.
Signs and symptoms
Typical clinical features of cardiovascular disease during pregnancy include distended jugular veins, diastolic murmurs, moist basilar pulmonary crackles, cardiac enlargement (discernible on percussion or as a cardiac shadow on chest X-ray), and cardiac arrhythmias (other than sinus or paroxysmal atrial tachycardia). Other characteristic abnormalities may include cyanosis, pericardial friction rub, pulse delay, and pulsus alternans.
Decompensation may develop suddenly or gradually, with persistent crackles at the lung bases. As it progresses, edema, increasing dyspnea on exertion, palpitations, a smothering sensation, and hemoptysis may occur.
Diagnosis
A diastolic murmur, cardiac enlargement, a systolic murmur of grade 3/6 intensity, and severe arrhythmia suggest cardiovascular disease. Determination of the disease’s extent and cause may necessitate electrocardiography, echocardiography (for valvular disorders such as rheumatic heart disease), or other studies. X-rays show cardiac enlargement and pulmonary congestion. Cardiac catheterization should be postponed until after delivery, unless surgery is necessary.
Treatment
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 often necessary and should always include the safest possible drug in the lowest possible dosage 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. Cardiac glycosides and common antiarrhythmics, such as quinidine and procainamide, are often required. The prophylactic use of antibiotics is reserved for patients who are susceptible to endocarditis.
A therapeutic abortion should be considered for patients with severe cardiac dysfunction, especially if decompensation occurs during the first trimester. Patients hospitalized with heart failure usually follow a regimen of cardiac glycosides, oxygen, rest, sedation, diuretics, and restricted intake of sodium and fluids. Patients in whom symptoms of heart failure don’t improve after treatment with bed rest and cardiac glycosides may require cardiac surgery, such as valvotomy and commissurotomy. During labor, the patient may require oxygen and an analgesic, such as meperidine or morphine, for relief of pain 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 birth. Forceps may augment vaginal delivery to minimize the need to push, which strains the heart.
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. Breast-feeding is undesirable for patients with severely compromised cardiac dysfunction because it increases fluid and metabolic demands on the heart.
Special considerations
❑ During pregnancy, stress the importance of rest and weight control to decrease the strain on the heart. Suggest a diet of limited fluid and sodium intake to prevent vascular congestion. Encourage the patient to take supplementary folic acid and iron to prevent anemia.
❑ During labor, watch for signs 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 program of treatment. Emphasize the need to rest during her hospital stay.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
» Next page: Pregnancy-induced hypertension (Professional Guide to Diseases (Eighth Edition))
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