[Congenital heart disease and acquired valvular lesions in pregnancy].

BACKGROUND

In Germany, about 6,000 pregnancies in women with grown-up congenital heart disease or acquired valvular lesions are expected per year. The pregnancy-related physiology is characterized by a 50% increase in plasma volume and a 25% increase in erythrocyte volume. The cardiac output increases by 40% due to 30% increase in stroke volume and 10% increase in heart rate during the first half, and 10% increase in stroke volume but 30% increase in heart rate during the second half of pregnancy. As a consequence of the decrease of systemic vascular resistance, the systolic and, even more, the diastolic blood pressures are reduced during approximately the first 20 weeks of pregnancy.

UNCORRECTED CONGENITAL LESIONS

Women with uncorrectable congenital heart disease, congestive heart failure (NYHA III and IV) despite optimized medical treatment after palliative surgery, or pulmonary vascular resistances > 800 dyn x s x cm(-5) should be advised against pregnancy. The presence of congestive heart failure or persistent cyanosis in the mother are the most important predictors of fetal hypoxia. Patients with pretricuspid shunts (e.g., atrial septal defect [ASD]) are at low risk of a hemodynamic deterioration or first onset of arrhythmias. In the rare case of a marked clinical deterioration, catheter-based closing of the shunt is the first-line treatment. Also, ventricular septal defects and persistent ducti arteriosi are usually well tolerated during pregnancy, as they are highly resistant to flow. In some cases, arrhythmias may occur. The prognosis is less favorable, if myocardial compromise has already been present before pregnancy. The fatal complication rate correlates closely with the degree of congestive heart failure. In aortic coarctation, development of severe hypertension, myocardial decompensation, aortic dissection, and cerebral hemorrhage have been reported in 2.3% of cases. To prevent aortic dissection and rupture of cerebral vascular aneurysms, patients should be advised to reduce their physical activity and have their blood pressure controlled closely. If, during pregnancy, a therapeutic intervention is unavoidable, stent placement is the therapy of choice. The maternal complication rate is low in pulmonary artery stenosis. Hemodynamically significant stenoses should be treated before pregnancy. In the rare case of progressive right heart failure or cyanosis during pregnancy, balloon valvotomy is the first-line therapeutic option.

CONGENITAL HEART DISEASE WITH PRIOR PALLIATION

Women with incomplete correction of a tetralogy of Fallot or significant residual gradients or shunts carry a particular risk of myocardial deterioration. A maternal hematocrit > 60%, an arterial O(2) saturation < 80%, markedly elevated right ventricular pressures, and the former presentation of syncopes are indicators of a poor prognosis. Fatal complication rates have been reported in 3-17% of cases. Other cyanotic lesions have been linked with a poor maternal and fetal prognosis. A 32% incidence of severe cardiovascular complications (pump failure, thromboembolic events, life-threatening arrhythmias, infective endocarditis) has been reported during 96 pregnancies of women with cyanotic heart disease. In addition, the frequency of abortions, premature birth, fetal distress, and congenital malformation of the child was 57%.

ACQUIRED VALVE LESIONS

Mitral stenosis is the lesion that most frequently requires therapeutic intervention during pregnancy, as the transmitral flow increases and time of diastole decreases during pregnancy due to the increase in cardiac output and heart rate. A consequent increase in mean pulmonary artery pressure by approximately 50% and a deterioration by one to two NYHA classes must be expected. While patients with a mitral orifice area > 1.5 cm(2) can usually be treated medically, more advanced mitral stenoses often require percutaneous mitral balloon valvotomy, a procedure with a very low complication rate in experienced centers. A chronic mitral or aortic regurgitation without jeopardized myocardial function is usually well tolerated during pregnancy, as the drop in peripheral vascular resistance results in a favorable left ventricular impedance, which reduces the transmitral regurgitant fraction and improves left ventricular antegrade ejection. Moreover, the increase in heart rate limits diastolic transaortic regurgitation. Hemodynamically advanced aortic stenosis is rare among patients in child-bearing age. The hemodynamic changes during pregnancy result in a decrease of the transaortic flow per time and thus in a decrease of the transaortic pressure loss. On the other hand, myocardial wall stress and oxygen consumption are significantly increased. If aortic valve orifice area is > 1.5 cm(2), the hemodynamic situation is usually well tolerated during pregnancy. In the case of more advanced aortic stenosis, there is a considerable risk of myocardial decompensation. The development of symptoms such as dyspnea, near syncopes or syncopes, and arrhythmias are indicators of a complicated course. If treatment is unavoidable, aortic valve replacement is the therapy of choice.

ORAL ANTICOAGULATION

With respect to anticoagulation during pregnancy, there is an ongoing debate about the potential risk and benefit of phenprocoumon, standard heparins, and low molecular heparins. Withdrawal of any anticoagulation results in the most favorable fetal outcome, oral anticoagulation throughout pregnancy in the best prognosis for the mother. An individual approach by an experienced center taking all therapeutic options into account is probably the best strategy.