Both transthoracic and transesophageal echocardiography can be performed at any stage of pregnancy. Expected physiologic changes in echocardiographic parameters during pregnancy are outlined in Table 41.2 . These parameters return to baseline within 3 to 6 months postpartum. In normal pregnancy, left ventricular diastolic function is increased in the first two trimesters and declines in the third trimester. Forty percent of patients with preeclampsia have evidence of global diastolic dysfunction, compared with 14% of normotensive pregnant patients (see Chapter 35 ).

Although there are limited data regarding echocardiographic contrast agents during pregnancy and lactation, no evidence of fetal harm has been identified in animal studies. Given the very brief half-life of these agents, no fetal or infant harm is expected and the use of these agents during pregnancy and lactation is acceptable if required for optimal maternal care.

Pregnant patients usually require anesthesia care for transesophageal echocardiography. The risk for pulmonary aspiration of gastric contents associated with sedation (with an unprotected airway) should be weighed against the risks associated with general anesthesia and tracheal intubation. Tracheal intubation is frequently for used for transesophageal echocardiography beyond 18 weeks’ gestation to reduce the risk of aspiration. If the uterine fundus is above the umbilicus, the patient should be positioned in the left lateral decubitus position to avoid inferior vena cava compression.

The risks associated with magnetic resonance imaging (MRI) in pregnant women are similar to those in nonpregnant patients, and there is no evidence that MRI causes harm to the fetus. Given the quality of images and diagnostic yield, cardiac magnetic resonance (CMR) is typically preferable to any imaging modality that uses ionizing radiation. Gadolinium crosses the placenta and has been found to be teratogenic in animal models. Currently available human data suggest that gadolinium should not be used in pregnant women unless it significantly improves diagnostic performance and is expected to improve maternal or neonatal outcome. There is minimal excretion of gadolinium into breast milk, and lactation should not be interrupted following its administration.

Coronary angiography remains the “gold standard” for diagnosis of coronary artery disease and can be performed at any time during pregnancy. Radial arterial access is preferable to femoral access because it is associated with earlier ambulation, increased patient comfort, and fewer access-related bleeding complications. The left lateral decubitus position can be more easily maintained with radial access. Pulmonary arterial catheterization may be required for mWHO class IV patients, including those with pulmonary hypertension, decompensated heart failure, or severe left-sided valvular obstruction. For all catheterization procedures, cardiologists should strictly adhere to the ALARA principle (as low as reasonably achievable) to limit both maternal and fetal ionizing radiation exposure (see Chapter 18 ). Typical ionizing radiation dose of a diagnostic or therapeutic cardiac catheterization is between 3 and 20 mGy, below the accepted fetal radiation threshold of 50 mGy.

Multidetector computed tomography (CT) allows noninvasive imaging of the coronary arteries along with cardiac structure and function. The use of contemporary CT with aggressive dose-reduction techniques can significantly limit the radiation dose. The overall radiation dose of chest CT imaging is 0.03 to 0.66 mGy.

The use of iodinated contrast media in pregnant and lactating women appears safe. To date, there has been no report of fetal teratogenic or mutagenic effects after maternal administration of iodinated contrast media. Minimal amounts of iodinated contrast media are excreted in breast milk; even smaller amounts are absorbed by the neonate’s gastrointestinal tract. Therefore, interruption of breastfeeding after maternal administration of iodinated contrast media is not recommended.

The ionizing radiation dose to the fetus can be limited by performing cardiac imaging with echocardiography or MRI techniques. If cardiac catheterization is necessary, the radiation dose can be limited by using reduced fluoroscopy frame rates and contemporary image noise-reduction technology. Because the fetus is not directly within the radiation beam for cardiac procedures, the fetal exposure occurs primarily through indirect scatter radiation. No deterministic radiation effects are expected at any gestational age for fetal radiation exposure < 50 mGy. Risks increase with doses > 100 mGy and with first-trimester exposure. Risks and benefits of the cardiac imaging modality in pregnancy should always be considered with the aim to maximize diagnostic accuracy and therapeutic efficacy while minimizing potential risks of radiation exposure.

Angiotensin-converting enzyme (ACE) inhibitors are the mainstay treatment of coronary artery disease, left ventricular dysfunction, and hypertension in nonpregnant patients. These drugs are particularly useful in nonpregnant patients with diabetes mellitus. However, they are contraindicated during pregnancy ( Box 41.8 ).

Few data are available on the use of angiotensin receptor blockers in pregnancy. However, similar to ACE inhibitors, the use of these drugs is not recommended during pregnancy.

Beta-adrenergic receptor antagonists are often used for treatment of coronary artery disease, myocardial infarction, hypertension, many arrhythmias, and a wide spectrum of cardiomyopathies. There is no evidence that beta-adrenergic receptor antagonists are teratogenic. Prolonged and high-dose use of these drugs has been associated with fetal growth restriction; however, the overall risk is likely small. Neonatal bradycardia, hypotension, and hypoglycemia are rarely encountered.

All calcium channel blockers in typical clinical doses appear safe during pregnancy. This includes nondihydropyridine calcium channel blockers such as verapamil and diltiazem , which are effective treatments for cardiac arrhythmias in the second and third trimesters. Dihydropyridine calcium channel blockers are also considered safe ( amlodipine , nifedipine , nicardipine , and clevidipine ). Oral nifedipine is frequently used in pregnancy. It has been reported to lower blood pressure more quickly with greater reduction of cerebral perfusion pressure than IV labetalol and, therefore, has become a first-line agent to treat preeclampsia with severe features. The use of both oral and IV nicardipine has also been described in pregnancy; infusion of IV nicardipine has been shown to achieve blood pressure control after failure of other antihypertensive agents in women with preeclampsia.

In nonpregnant patients, many anesthesia providers consider clevidipine the drug of choice for acute and rapid control of hypertension since the ECLIPSE trials demonstrated the drug’s superiority in cardiac surgery. Animal studies show that it crosses the placenta; when administered for prolonged periods at supratherapeutic doses, it is associated with an increased incidence of intrauterine fetal death, reduced fetal weight, and delayed skeletal development. There are no data indicating harm at typical clinical doses, and there are few descriptions of its use in human pregnancy. In the setting of a maternal hypertensive emergency with failure of other agents, clevidipine’s ultrashort half-life may make it a reasonable option for rapid arterial blood pressure reduction.

Calcium channel blockers have tocolytic effects by limiting calcium ion entry into myometrial smooth muscle cells. In vitro testing indicates that diltiazem and verapamil display greater concentration-dependent inhibition of spontaneous human pregnant myometrium than nifedipine (i.e., nifedipine exhibits the least degree of tocolysis).

Amiodarone is generally avoided in pregnancy because animal studies have shown evidence of fetal toxicity at doses less than the maximum recommended human maintenance dose. Further, in humans, congenital goiter/hypothyroidism, hyperthyroidism, and neonatal bradycardia have been reported. However, its safe and effective use has been reported for the treatment of drug-refractory fetal tachycardia in the setting of hydrops fetalis or ventricular dysfunction. Similarly, in the setting of an acute unstable maternal arrhythmia, the benefits of maternal amiodarone therapy may outweigh the risks.

Hydralazine is used in the treatment of cardiomyopathy and is also an excellent antihypertensive agent. It has a long track record of safe use during pregnancy, especially in women with preeclampsia (see Chapter 35 ).

The use of nitrates for treatment of angina during pregnancy appears safe. They can be safely used long term in pregnant women with cardiomyopathy. Nitrates can have profound acute tocolytic effects because nitric oxide directly inhibits myometrial contractions.

Digoxin may be useful for the treatment of various cardiomyopathies and some arrhythmias. Digoxin freely crosses the placenta, but its use has not been associated with congenital abnormalities or untoward fetal effects. Digoxin’s pharmacokinetics are altered during pregnancy; monitoring of blood levels is recommended.

Various antiplatelet drugs may be prescribed for patients with coronary artery disease, after stent placement, with acute coronary syndrome (ACS), or after heart valve replacement. For example, eptifibatide , tirofiban , and abciximab are potent platelet aggregation inhibitors (IIB/IIIA receptor inhibitors) administered intravenously (IV) to inhibit platelet aggregation during percutaneous coronary intervention. Adenosine diphosphate receptor blockers such as clopidogrel , ticagrelor , ticlopidine , and prasugrel and phosphodiesterase inhibitors such as dipyridamole and cilostazol may also be used. Both the American Society of Regional Anesthesia and Pain Medicine and the European Society of Anaesthesiology guidelines strongly advise avoidance of neuraxial anesthesia until platelet function has recovered after administration of antiplatelet agents.

Statins interrupt cholesterol synthesis and result in a lowering of plasma cholesterol levels. The widespread use of statins (which are associated with exceptionally robust cardiovascular outcome data) has transformed the treatment of coronary artery disease. Nonetheless, given the critical importance of cholesterol synthesis in the normal development of the embryo and placenta, statins are contraindicated in pregnancy, given their potential for teratogenicity.

Thiazide diuretics do not appear to be teratogenic. Long-term use may result in a reduction in uteroplacental perfusion, which may be associated with fetal growth restriction and oligohydramnios. Neonatal hypoglycemia and thrombocytopenia have been reported.

Loop diuretics are likely not teratogenic. Similar to thiazide diuretics, fetal growth restriction may be associated with long-term use during pregnancy. Spironolactone is an aldosterone antagonist frequently used in the treatment of patients with congestive heart failure and cardiomyopathy, but because of its antiandrogenic potential, its use during pregnancy is not recommended. Data are inadequate to determine the safety of sacubitril , empagliflozin , and dapagliflozin use during pregnancy.

Patients with an undiagnosed ASD may remain asymptomatic until late in life, or they may become symptomatic for the first time during pregnancy. The most common defect is the secundum-type ASD (80%), whereas the primum, sinus venosus, and coronary sinus types of ASD are less common. Repaired ASD without long-term sequelae is a mWHO class I condition with no significantly increased risk of cardiovascular complications during pregnancy. Unrepaired ASD is a mWHO class II lesion, with increased risk of right ventricular volume overload, atrial arrhythmias, and paradoxical embolism. Less than 5% of patients with an ASD develop pulmonary hypertension, in which case pregnancy risk is considered prohibitively high. Intravenous line bubble filters should be used in these patients recognizing that, at times, such as in the setting of a propofol infusion or a massive transfusion requiring rapid transfusion, they may need to be removed. Typical obstetric and anesthetic management is generally recommended for patients with repaired and unrepaired ASD (see Table 41.5 ).

There are four types of ventricular septal defects (VSDs); the most common type is a perimembranous VSD. Pregnancy is well tolerated (mWHO class I) in patients with a repaired or restrictive (small) VSD in the absence of pulmonary hypertension. An unrepaired nonrestrictive VSD with Eisenmenger syndrome is associated with a prohibitively high risk for maternal cardiac complications (see discussion below). The risk of paradoxical embolism is minimal given the significant left-to-right pressure gradient between the left and right ventricle. Typical obstetric and anesthetic management (vaginal delivery with neuraxial analgesia) is generally recommended (see Table 41.5 ).

Pregnancy is well tolerated in patients with a repaired, silent, or small patent ductus arteriosus (PDA), and complications are rare (mWHO class I). Typical obstetric and anesthetic management (vaginal delivery with neuraxial analgesia) is generally recommended (see Table 41.5 ). An unrepaired large PDA may cause pulmonary hypertension, and pregnancy is not recommended because of prohibitively high risk.

Repaired coarctation of the aorta is generally considered a mWHO class II to III risk, depending on whether there is any residual gradient or aneurysm. Severe unrepaired coarctation is considered mWHO class IV and pregnancy is not recommended until the coarctation has been repaired. Systemic arterial hypertension is a common long-term sequela of coarctation even after repair, and several studies report increased risk of hypertensive disorders of pregnancy. Coarctation is associated with a bicuspid aortic valve in more than half the patients, and 10% of adults develop intracranial aneurysms. Prepregnancy evaluation of the coarctation, including residual degree of obstruction, evidence of aortic aneurysm and associated anomalies, is recommended. Typical obstetric and anesthetic management (vaginal delivery with neuraxial analgesia) is generally recommended. Blood pressure measurements should be obtained in the right arm as typically left arm pressures are falsely reduced, even in repaired patients.

Single ventricle palliation is a multistep procedure that establishes blood flow from the venous system to the pulmonary artery by bypassing the right ventricle ( Fig. 41.1 ). It is performed for cyanotic heart defects that cannot undergo a two-ventricle repair, typically related to severe underdevelopment of either the left or right ventricle. Common conditions leading to this type of repair include tricuspid or pulmonary atresia and hypoplastic left heart syndrome. Because there is no functional subpulmonic ventricle, right-sided filling pressures are chronically elevated and patients have limited capacity to augment cardiac output. Common long-term complications include atrial arrhythmias (which are poorly tolerated), hepatic fibrosis with liver dysfunction, development of pulmonary collateral vessels with shunting and cyanosis, single ventricular systolic and diastolic dysfunction, atrioventricular (AV) valve regurgitation, lower extremity venous stasis, and protein-losing enteropathy.

Schematic Depiction of a Fontan Repair. There is no functional right ventricle. The white lines with arrows represent the pathway of venous blood returning to the heart.

Illustration by Naveen Nathan, MD, NorthShore University HealthSystem, University of Chicago Pritzker School of Medicine, Evanston, IL.

Pregnancy is considered mWHO class III for functional patients with single ventricle palliation and mWHO class IV for patients with evidence of Fontan failure (clinical cirrhosis, protein-losing enteropathy, symptomatic heart failure, plastic bronchitis). Patients with a Fontan repair are at increased risk for arrhythmias, symptomatic heart failure, and thromboembolism during pregnancy. There is a high rate of fetal complications for patients with single ventricle palliation, including miscarriage, stillbirth, preterm birth, and fetal growth restriction.

Patients with a Fontan repair are preload dependent and should be adequately hydrated during labor and delivery (see Table 41.5 ). Laboring in the left lateral decubitus position may be considered. A vaginal delivery with early, slowly titrated neuraxial anesthesia is generally recommended. The use of neuraxial anesthesia for operative delivery avoids the adverse effects of myocardial depression and positive-pressure ventilation on the Fontan circulation. Patients may require a low threshold for assisted second stage of labor, given their dependence on preload.

Intravenous bubble filters should be used if the patient has a patent Fontan fenestration or venovenous collaterals to reduce the risk of paradoxical embolism. Oxygen saturation commonly decreases in the third trimester in these patients, owing to increased shunting through venovenous collaterals. The desaturation often does not respond to supplemental oxygen.

Transposition of the great arteries (TGA) comprises two distinct groups: complete TGA (D-transposition) and congenitally corrected TGA (L-transposition). In both conditions, the aorta originates from the right ventricle and the pulmonary artery originates from the left ventricle. Patients with L-TGA are not born cyanotic and often have not undergone previous cardiac surgery unless they were born with additional cardiac defects such as a VSD.

D-TGA manifests as neonatal cyanosis and patients born with this condition will have undergone surgical correction. This was previously performed via an atrial switch procedure (Senning or Mustard), and the right ventricle functions as the systemic ventricle. Atrial arrhythmias, systemic right ventricular dysfunction, systemic tricuspid regurgitation, atrial baffle obstruction or leaks, and pulmonary hypertension are common long-term complications.

In the contemporary era, an arterial switch procedure (Jatene) is performed and the left ventricle is the systemic ventricle. The most common complications include myocardial ischemia due to coronary button reimplantation and neoaortic regurgitation due to dilation of the neoaortic root.

Pregnancy is considered mWHO class III for patients with a systemic right ventricle (L-TGA or D-TGA with atrial switch). Patients with a systemic right ventricle carry increased risk for atrial arrhythmias (15%), symptomatic heart failure (10%), and worsening systemic tricuspid regurgitation during pregnancy.

All women with TGA require detailed echocardiography prior to planned pregnancy. Typical obstetric and anesthetic management (vaginal delivery with neuraxial analgesia) is generally recommended for patients with a history of TGA (see Table 41.5 ). Neuraxial anesthesia is recommended, with consideration of slowly titrated dosing for patients with systemic right ventricles because of their preload dependence. Patients with systemic right ventricular dysfunction or significant systemic tricuspid regurgitation are at increased risk for pulmonary edema, and volume status should be monitored closely. Telemetry monitoring is generally recommended because of the increased risk of atrial arrhythmias.