Management of Classes I and II:

Most of the women in class I and II undergo pregnancy without morbidity; however, special attention should be directed toward both prevention and early recognition of heart failure. Infection has proved to be an important factor in precipitating cardiac failure. Each woman should receive instructions to avoid contact with persons who have respiratory infections, including common cold, and to report at once any evidence for infection. Bacterial endocarditis is a deadly complication of valvar heart disease. Pneumococcal and influenza vaccines are recommended. Cigarette smoking is prohibited, both because of its cardiac effects as well as the propensity to cause upper respiratory infections. The onset of congestive heart failure is generally gradual. The first warning sign is likely to be persistent basilar rales, frequently accompanied by a nocturnal cough. A sudden diminution in ability to carry out usual duties, increasing dyspnea on exertion, or attacks of smothering with cough is symptoms of serious heart failure. Clinical findings may include hemoptysis, progressive edema, and tachycardia.

Labor and Delivery: In general, delivery should be accomplished vaginally unless there are obstetrical indications for cesarean delivery. Relief from pain and apprehension is especially important. While intravenous analgesics provide satisfactory pain relief for some women, continuous epidural analgesia is recommended for most situations. The major danger of conduction analgesia is maternal hypotension. This is dangerous in women with intracardiac shunts, in whom flow may be reversed with blood passing from the right-to-left within the heart or aorta, thereby bypassing the lungs. Hypotension can be hazardous with pulmonary hypertension or aortic stenosis because ventricular output is dependent upon adequate preload. In women with these conditions, narcotic conduction analgesia or general anesthesia may be preferable.

During labor, the mother with significant heart disease should be kept in a semirecumbent position with lateral tilt. Vital signs should be taken frequently between contractions. Increases in pulse rate much above 100 per minute or in the respiratory rate above 24, particularly when associated with dyspnea, may suggest impending ventricular failure. With any evidence of cardiac decompensation, intensive medical management must be instituted immediately. It is essential to remember that delivery itself will not necessarily improve the maternal condition. Moreover, emergency operative delivery may be particularly hazardous. Clearly, both maternal and fetal conditions must be considered in the decision to hasten delivery under these circumstances. For cesarean delivery, epidural analgesia is preferred by most clinicians; spinal analgesia is contraindicated with some lesions and general endotracheal anesthesia with thiopental, succinylcholine nitrous oxide, and at least 30% oxygen has also proved satisfactory.

Intrapartum Heart Failure: Unless the underlying pathophysiology is understood and the cause of the decompensation clear, empirical therapy is hazardous. Cardiovascular decompensation during labor may manifest as pulmonary edema and hypoxia, hypotension or both. The proper therapeutic approach will depend upon the specific hemodynamic status and the underlying cardiac lesion. For example, decompensated mitral stenosis with pulmonary edema due to absolute or relative fluid overload is often best approached with aggressive diuresis, or if precipitated by tachycardia, by heart rate control with beta-blocking agents. On the other hand, the same treatment in a woman suffering decompensation and hypotension due to aortic stenosis could prove fatal (5).

Postpartum: Women who have shown little or no evidence of cardiac distress during pregnancy, labor or delivery may still decompensate after delivery. Therefore, it is important that meticulous care be continued into the postpartum period. Postpartum hemorrhage, anemia, infection, and thromboembolism are much more serious complications with heart disease and may act as precipitating factors in heart failure. If tubal ligation is to be performed after vaginal delivery, it may be best to delay the procedure until it is obvious that the mother is afebrile, not anemic, and has demonstrated that she can ambulate without evidence of distress. Women who do not undergo tubal sterilization should be given detailed contraceptive advice.

Management of Classes III and IV:

These severe cases are uncommon today in industrialized countries. The important question in these women is whether pregnancy should be undertaken. If women choose to become pregnant, they must understand the risks and cooperate fully with planned care. If seen early enough, women with some types of severe cardiac disease should consider pregnancy interruption. If pregnancy is continued, prolonged hospitalization or bed rest will often be necessary. As for less severe disease, epidural analgesia for labor and delivery is usually recommended. Vaginal delivery is preferred in most cases, and cesarean delivery is limited to obstetrical indications. The decision for cesarean delivery must take into account the specific cardiac lesion, overall maternal condition, availability and experience of anesthetic support, as well as physical facilities. These women often tolerate major surgical procedures poorly, and should be delivered in a facility with experience with complicated cardiac disease.

Cardiac Surgery during Pregnancy:

Valve Replacement during Pregnancy: Although usually postponed, valve replacement during pregnancy occasionally may be lifesaving. A number of reviews and small series all confirm that surgery on the heart or great vessels is associated with major maternal and fetal morbidity and mortality (6). Valvar surgery is associated with about 9% maternal mortality and perinatal mortality about 30%. The fetal response to cardiopulmonary bypass pump during surgery is usually bradycardia, and high-flow normothermic perfusion is recommended.

Mitral Valvotomy during Pregnancy: This operation is less common because the incidence of rheumatic mitral stenosis has declined. Within the past 20 years, percutaneous trans-catheter balloon dilatation of the mitral valve has largely replaced surgical valvoplasty during pregnancy. The normal mitral valve surface area is 4.0 cm2. When stenosis narrows this to less than 2.5 cm2, symptoms usually develop. The most prominent complaint is dyspnea due to pulmonary venous hypertension and pulmonary edema. Other common symptoms are fatigue, palpitation, cough, and hemoptysis. Coexisting atrial fibrillation is especially ominous and commonly was associated with heart failure, thromboembolic disease and death.

American Heart Association Guidelines for Bacterial Endocarditis Prophylaxis for Genitourinary and Gastrointestinal Procedures (2000):

High-risk patients - Ampicillin and Gentamicin: Intravenous or intramuscular ampicillin, 2 g, plus gentamicin, 1.5 mg/kg (not to exceed 120 mg), within 30 min. before the procedure, then ampicillin 1 g, intramuscularly or intravenously, or amoxicillin, 1 g orally, 6 hours after the initial dose.

Penicillin-allergic patients - Vancomycin and Gentamicin: Intravenous vancomycin, 1 g over 1-2 h, plus intravenous or intramuscular gentamicin, 1.5 mg/kg (not to exceed 120 mg); infusion to be completed within 30 min. before the procedure.

Moderate-risk patients - Amoxicillin or Ampicillin: Oral amoxicillin, 2 g orally, 1 h before the procedure, or ampicillin, 2 g either intravenously or intramuscularly within 30 min. of beginning the procedure.

Relative Risks for Infective Endocarditis with Various Types of Cardiac Lesions; Source: Dajani and colleagues (1997) (7)

High Risk: Prosthetic heart valves; previous endocarditis; complex congenital cyanotic heart disease; surgically constructed systemic pulmonary shunts.

Moderate Risk: Most other congenital malformations not in high or low risk categories; acquired valvar dysfunction - rheumatic heart disease; hypertrophic cardiomyopathy; mitral valve prolapse with valvar regurgitation and/or thickened leaflets.

Not Recommended: Atrial septal defect; surgically corrected lesions without prosthesis (ASD, VSD, PDA); coronary artery disease with previous bypass surgery; mitral valve prolapse without regurgitation; physiological murmurs; previous rheumatic fever without valvar dysfunction; pacemakers.

Summary

Ideally, the patient with known heart disease should consult her physician before becoming pregnant in order to determine the advisability and optimum timing for pregnancy, the need for and timing of diagnostic procedures, the prospects for corrective or palliative cardiac surgery, the type of prosthetic valve to be used, and the need for discontinuing certain drugs during pregnancy. If a woman with heart disease presents for medical care after she has become pregnant, the obstetrician must be able to recognize the presence of preexisting cardiac disease, assess the degree of disability, and understand the impact of the added hemodynamic changes of pregnancy. Pre-pregnancy planning might include performance of an exercise tolerance test to determine if the woman with severe heart disease can tolerate the added hemodynamic burden of pregnancy.

The obstetrician must also be able to anticipate, prevent, diagnose, and treat complications such as arrhythmia or congestive heart failure when they arise and advise the patient regarding discontinuation or continuation of the pregnancy and the risk of future pregnancies. Management of an obstetric patient with heart disease should be carried out by a team consisting of the obstetrician and obstetric nurse or midwife, as well as the cardiologist, anesthesiologist and neonatologist, at the time of labor.

References:

1. American College of Obstetricians and Gynecologists: Cardiac disease in pregnancy. Technical Bulletin No. 168, June 1992a.
2. American College of Obstetricians and Gynecologists: Invasive hemodynamic monitoring in obstetrics and gynecology. Technical Bulletin No. 175, December 1992b.
3. Brady K, Duff P; Rheumatic heart disease in pregnancy. Clin Obstet Gynecol 32:21, 1989.
4. Burrow GN, Duffy TP (eds): Medical Complications During Pregnancy, 5th ed. Philadelphia, Saunders, 1999, p 111.
5. Dajani AS, Taubert KA, Wilson W, Bolger AF, Bayer A, et al: Prevention of bacterial endocarditis. Recommendations of the American Heart Association. JAMA 277: 1794, 1997.
6. Siu SC, Sermer M, Harrison DA, et al: Risk and predictors for pregnancy-related complications in women with heart disease. Circulation 96:2789, 1997.
7. Thorhill ML, Camann WR: Cardiovascular disease, In Chestnut DH (ed): Obstetric Anesthesia. Mosby, St. Luis, 1994 p 746.