Pregnancy is well tolerated with small-to-moderate sized shunts. If pulmonary arterial pressures reach systemic levels, however, there is reversal or bidirectional Bow-Eisenmenger syndrome (p. 960). When this develops, the maternal and fetal mortality rates are signiicantly higher, and thus, pregnancy is not generally advisable. Bacterial endocarditis is more common with unrepaired defects, and antimicrobial prophylaxis is often required (p. 965). As shown in Table 49-4, 10 to 16 percent of ofspring born to these women also have a ventricular septal defect.
These account for approximately 3 percent of all congenital cardiac malformations and are distinct from isolated atrial or ventricular septal defects. An atrioventricular (A V) septal defect is characterized by a common, ovoid A V junction. his defect is associated with aneuploidy, Eisenmenger syndrome, and other malformations (Altin, 2015). Compared with simple septal defects, complications are more frequent during pregnancy. In a review of 48 pregnancies in 29 afected women, complications included persistent deterioration of NA class in 23 percent, signiicant arrhythmias in 19 percent, and heart failure in 2 percent (Drenthen, 2005b). Congenital heart disease was identiied in 15 percent of the ofspring.
The ductus connects the proximal left pulmonary artery to the descending aorta just distal to the left subclavian artery. Functional closure of the ductus from vasoconstriction occurs shortly after term birth. he physiological consequences with its persistence are related to its size. Most signiicant lesions are repaired in childhood, but for individuals who do not undergo repair, the mortality rate is high after the ifth decade (Brickner, 2014). In some younger women with an unrepaired ductus during pregnancy, however, pulmonary hypertension, heart failure, or cyanosis will develop if systemic blood pressure falls and leads to shunt reversal of blood from the pulmonary artery into the aorta (Vashisht, 2015). A sudden blood pressure decline at delivery-such as with regional analgesia or hemorrhage-may lead to fatal collapse. Accordingly, hypotension is ideally avoided but treated vigorously if it develops. Prophylaxis for bacterial endocarditis is indicated at delivery for unrepaired defects (p. 965). As shown in Table 49-4, the incidence of inheritance approximates 4 percent.
When congenital heart lesions produce right-to-Ieft shunting of blood past the pulmonary capillary bed, cyanosis develops. The classic and most commonly encountered lesion in adults and during pregnancy is the Fallot tetraloy (Lindley, 2015). his is characterized by a large ventricular septal defect, pulmonary stenosis, right ventricular hypertrophy, and an overriding aorta that receives blood from both the right and left ventricles. The magnitude of the shunt varies inversely with systemic vascular resistance. Hence, during pregnancy, when peripheral resistance declines, the shunt increases and cyanosis worsens.
Generally, women with cyanotic heart disease do poorly during pregnancy. With uncorrected Fallot tetralogy, maternal mortality rates approach 10 percent. here is a relationship between chronic hypoxemia, polycythemia, and pregnancy outcomes such as miscarriage and perinatal morbidity. When hypoxemia is intense enough to stimulate a rise in hematocrit above 65 vol umes percent, pregnancy wastage is virtually 100 percent.