Impact of Pregnancy on Common Cardiac Diagnostic Tests The surface electrocardiogram may show a sinus tachycardia Because of the change in position of the heart, the electrocardiogram may show a shift in the frontal plane axis or inversion of the T waves in the inferior leads The chest radiograph may show a more horizontal cardiac shadow because of elevation of the diaphragm and an enlarged cardiac silhouette The pulmonary vascular markings may become more prominent due to increased blood flow, simulating the vascularity produced by a systemic-to-pulmonary shunt Echocardiographically, the increase in blood volume manifests as mild increases in the dimensions of the atria and ventricles The left ventricular mass increases In normal pregnancies, the left ventricular systolic function is preserved The increased cardiac output is associated with an increase in velocity of flow across all cardiac valves Mitral regurgitation may either improve or worsen, depending on the relative impact of the fall in systemic vascular resistance versus the change in geometry of the mitral valvar apparatus associated with increasing chamber size Preconception Counseling and Contraception All women with congenital heart disease should have age-appropriate counseling regarding contraception and potential pregnancy beginning in adolescence The responsibility of providing such counseling often falls to the specialist in congenital cardiac disease caring for the woman at the time and his or her team, as the patient will often not have access to others qualified to offer knowledgeable advice Table 80.1 lists issues that should be addressed during preconception counseling Table 80.1 Approach to Preconception Counseling for Women With Heart Disease Component Contraception selection Maternal cardiac risk Description Review safety and reliability of contraception options Cardiac risk stratification by an expert in pregnancy and heart disease Determine if cardiac interventions are required prior to pregnancy Discuss cardiac risks of pregnancy Review medications and discontinue or modify as appropriate Discuss long-term prognosis Maternal obstetric risk Discuss maternal obstetric risks Fetal and neonatal risk Discuss fetal and neonatal risks Discuss risk of transmission of congenital heart disease to offspring Genetics referral when appropriate Pregnancy planning Discuss general pregnancy care planning including antenatal follow-up and delivery location Commonly, information regarding diagnosis, previous procedures, and prognosis are not known to patients or are misunderstood by them Clarification of diagnosis and functional capacity are fundamental to effective preconception counseling The specialist in congenital cardiac disease is well suited to this task and also to ensuring that this information is provided to other caregivers involved in the management of the pregnancy and understood by them Discussion of long-term prognosis of the mother may be straightforward or very complex and sensitive, depending on the underlying cardiac lesion, the types of surgical interventions, the residual lesions, and comorbid medical conditions Because maternal cardiac status can change over time, women with congenitally malformed hearts should be advised to ensure regular follow-up and, in particular, to obtain a contemporaneous updated assessment prior to finalizing a decision to pursue pregnancy We discuss maternal and fetal risks associated with pregnancy in the later sections of this chapter When pregnancy is actively considered or when the woman presents in a gravid condition, the assessment must incorporate advice about the proper level of obstetric and multidisciplinary care during pregnancy Most women with congenital heart disease will benefit from an initial cardiac and high-risk obstetric (maternal fetal medicine) consultation Those with minor lesions and their caregivers and families can be reassured regarding the low risk of adverse events and the appropriateness of standard obstetric care Women at higher risk can be referred appropriately to high-risk obstetric units in order to have access to specialists with experience in managing complex cardiac disease throughout pregnancy For women who do not wish to become pregnant, the safety and efficacy of various types of contraception must be considered Recommendations regarding proper use of contraceptives have been extrapolated from studies in women without cardiac disease and are based on expert opinion.1,2 Barrier methods do not pose a health risk to the mother but are associated with high rates of failure Up to one-third of women using barrier techniques alone will have an unintended pregnancy within the first year of use Barrier methods alone, therefore, should not be recommended as effective contraceptive choices to women in whom there is a significant maternal risk of pregnancy, although condoms may be used in conjunction with other methods Combined estrogen and progestin oral contraceptives have good efficacy, but the estrogen component is associated with an increased risk of thrombosis, which constrains their use in women with cyanotic cardiac disease, Fontan circulation, significant systemic ventricular dysfunction, sustained arrhythmias, mechanical valves, and/or prior thromboembolic events The risk of stroke in association with combined oral contraceptives is further increased if a woman has a history of hypertension, diabetes, obesity, smoking, or migraine headaches Estrogens and progestins can interfere with the metabolism of warfarin, and international normalized ratios need to be monitored more closely in women using these forms of contraception Progestin-only oral contraceptives are safe in women with heart disease but are associated with higher rates of failure compared with combined oral contraceptives and should not be used in women with cardiac disease who face substantial risk of pregnancy Insertion of an intrauterine device is often a safe and reliable option for women with heart disease In some