Cardiovascular Diseases During Pregnancy: Diagnosis and Management

Prepared by Dr. Gintarė Pukanasienė

Introduction

Pregnancy is a condition in which various physiological changes occur in different organ systems, including the digestive, respiratory, circulatory, and endocrine systems. With regard to the cardiovascular system, increased metabolic demands during pregnancy lead to an increase in cardiac output, determined by increases in heart rate and stroke volume (1). In a healthy heart, as atrial and ventricular parameters increase, ventricular function is maintained. However, in patients with heart disease, inadequate adaptation of the left and right ventricles may occur during pregnancy (2).

Peripheral vasodilation is also observed, together with a decrease in systemic and pulmonary vascular resistance. At the end of pregnancy, when a woman is in the supine position, the inferior vena cava may be compressed by the greatly enlarged uterus, leading to reductions in venous blood flow, stroke volume, and cardiac output. It is important to note that pregnancy is a hypercoagulable state, increasing the risk of thromboembolic complications.

In modern society, improvements in the treatment of congenital heart disease, the increasing age of pregnant women, and the growing number of pregnant women with arterial hypertension (AH), coronary heart disease, or a history of corrective cardiac or valvular surgery mean that such patients are encountered increasingly often. It is crucial to understand the risks posed by cardiovascular diseases to both the mother and the fetus, as their treatment may affect not only maternal but also fetal health and survival (3). This article discusses the main cardiovascular conditions in pregnant women and optimal treatment methods.

Hypertensive Disorders and Their Treatment During Pregnancy

Hypertensive disorders are among the most common medical problems during pregnancy, affecting up to 5–10% of all pregnancies worldwide and being associated with increased maternal, fetal, and neonatal morbidity and mortality. Hypertensive disorders are associated with a higher risk of placental abruption, stroke, organ dysfunction, and disseminated intravascular coagulation in the mother, as well as fetal growth restriction, preterm birth, and intrauterine fetal death (4).

Elevated blood pressure (BP) is diagnosed in either an outpatient or inpatient setting when systolic BP (SBP) is ≥140 mm Hg and/or diastolic BP (DBP) is ≥90 mm Hg, although the classification of arterial hypertension (AH) differs from that used in the general population. Moderate BP elevation is defined as 140–159/90–109 mm Hg, while severe AH is diagnosed when BP is ≥160/110 mm Hg (5).

It is important to emphasize that BP during pregnancy should be measured in a sitting position using a manual sphygmomanometer, as automatic BP monitors are not reliable in severe preeclampsia. All patients with elevated BP during pregnancy should undergo additional testing, including a complete blood count, urinalysis, urea measurement, and liver function tests. To detect preeclampsia, proteinuria should be assessed and the albumin/creatinine ratio determined (6). In individual cases, when rare diseases causing AH are suspected, ultrasonography of the adrenal glands and renal blood vessels, as well as urinary metanephrine testing, should be considered.

According to the guidelines of the European Society of Cardiology (ESC), hypertensive disorders during pregnancy are classified as chronic (primary or secondary), gestational, chronic hypertension complicated by preeclampsia, unclassified AH, and preeclampsia. The main risk factors for AH and preeclampsia are elevated BP during previous pregnancies, chronic kidney disease, autoimmune diseases such as systemic lupus erythematosus and antiphospholipid syndrome, type 1 or type 2 diabetes, late pregnancy (>40 years of age), increased BMI (>35 kg/m²), multiple pregnancy, and a family history of preeclampsia.

The treatment of AH during pregnancy depends on the degree of BP elevation, duration of pregnancy, and maternal and fetal risk factors. Non-pharmacological treatment alone does not have a significant effect on reducing BP or improving pregnancy outcomes, but dietary and lifestyle changes, including maintaining physical activity and limiting weight gain in obese pregnant women to ≤6.8 kg, are recommended in conjunction with medication use (7).

Medical treatment is recommended for all women when SBP is ≥150 mm Hg or DBP is ≥95 mm Hg, or when BP is >140/90 mm Hg in cases of gestational hypertension, previously diagnosed hypertension that worsens during pregnancy, or established target organ damage (8). Pregnant women are usually treated with methyldopa, beta-adrenoblockers (BAB; labetalol), or calcium channel blockers (CCB; nifedipine) (9). BAB are less effective than CCB and may cause fetal bradycardia, growth retardation, and hypoglycemia; therefore, appropriate doses must be selected.

ACE inhibitors, ARBs, and direct renin inhibitors are contraindicated for the treatment of BP elevation during pregnancy. Reduced plasma volume is observed in preeclampsia, so diuretics should be avoided. In cases of severe BP elevation (≥170/110 mm Hg), further treatment in hospital is recommended. The choice of medication depends on the planned timing of completion of the pregnancy. Treatment usually begins with intravenous labetalol, oral methyldopa, or nifedipine. Hydralazine and sodium nitroprusside are not recommended because of possible adverse effects on the fetus (10, 11).

In cases of preeclampsia with pulmonary edema, treatment with intravenous nitroglycerin is recommended. The main recommendations for the treatment of hypertensive disorders according to the ESC are presented in Table 1.

Table 1. ESC Recommendations for the Treatment of Hypertensive Disorders During Pregnancy

Treatment of Coronary Heart Disease During Pregnancy

The incidence of acute coronary syndromes (ACS) in pregnant women is low; however, coronary heart disease is associated with more than 20% of cardiovascular deaths in pregnant women (12). The etiology of coronary heart disease in pregnant women differs from that in the general population. In many cases, atherosclerotic coronary artery disease is not the predominant cause; instead, pregnancy-related spontaneous coronary artery dissection, thrombosis, or myocardial infarction without changes in the coronary vessels may occur (13, 14).

Spontaneous coronary artery dissection may be related to fluctuating estrogen and progesterone levels, which cause structural changes in the coronary arteries, as well as increased vascular dilation during childbirth. Thrombosis is most commonly caused by a hypercoagulable state. Paroxysmal embolization is also possible (15).

Most cases of ACS occur during the third trimester or postpartum. ECG assessment is more complex because T-wave inversion may be observed during pregnancy even in the absence of myocardial ischemia. An increase in serum troponin concentration should be considered a sign of myocardial infarction even in the presence of diagnosed preeclampsia (16).

Recommendations for the treatment of ACS in pregnant women are similar to those for the general population. However, it is important to emphasize that in hemodynamically stable, low-risk patients with non-ST-elevation acute myocardial infarction (NSTEMI), a conservative treatment strategy may be considered. In patients requiring interventional treatment, it is important to reduce the dose of ionizing radiation received during interventional radiological procedures.

With regard to pharmacological treatment, pregnancy is associated with an increased risk of bleeding; therefore, high-potency P2Y12 inhibitors, such as prasugrel and ticagrelor, should be selected with caution. There is also insufficient information on the use of glycoprotein IIb/IIIa inhibitors, such as abciximab and tirofiban. Therefore, the currently recommended treatment is a combination of aspirin and clopidogrel, with clopidogrel administered as soon as possible.

Heart Valve Diseases and Their Treatment During Pregnancy

Heart valve diseases in patients of reproductive age are more common in developing countries, where rheumatism remains highly prevalent. Another important issue for pregnant women is the presence of mechanical prosthetic valves and the need for anticoagulant therapy. In heart defects causing stenosis, increased cardiac output leads to a 50% increase in the transvalvular gradient, thereby increasing the risk of complications for both the fetus and the mother.

Although mitral stenosis is well tolerated, approximately one-third of patients with a valve area of less than 1 cm² may develop symptoms and signs of heart failure during pregnancy. Pharmacological treatment is recommended in cases of severe symptoms or clinically significant pulmonary hypertension (17). Recommended treatment includes low doses of selective beta-blockers, such as metoprolol and bisoprolol. In cases of paroxysmal or permanent atrial fibrillation (AF), left atrial thrombi (LAT), or previous thromboembolism, unfractionated heparin (UFH), low molecular weight heparins (LMWH), or vitamin K antagonists (VKA) are recommended.

The use of anticoagulants should also be considered in patients with sinus rhythm but severe mitral stenosis, spontaneous contrast filling of the LAT, marked LAT dilation, or congestive heart failure (CHF) (17). Pregnancy is not recommended for patients with severe mitral stenosis, and interventional procedures should be performed before pregnancy.

With regard to aortic valve (AoV) stenosis, disease progression and mortality during pregnancy depend on the severity of aortic stenosis and the presence of symptoms. CHF occurs in up to 10% of patients with moderate AoV stenosis who were asymptomatic before pregnancy; among symptomatic patients, the incidence of CHF during pregnancy may reach 25% (18). Although pregnancy is generally well tolerated and maternal mortality and severe complications are rare, fetal growth restriction, preterm birth, and low birth weight occur in approximately 20–25% of cases (18).

Pharmacological treatment is important when symptoms of CHF develop, and diuretics may be prescribed when signs of congestive CHF are present. As with mitral stenosis, patients with severe AoV stenosis and impaired AoV function should be advised to avoid pregnancy, and all interventional procedures should be performed beforehand.

Regurgitant heart valve diseases may be associated with rheumatic, degenerative, or congenital changes. Patients with significant valve regurgitation accompanied by symptoms or impaired valve function are at high risk of CHF (19). According to the literature, up to 20–25% of patients diagnosed with moderate or severe rheumatic mitral valve regurgitation (MVR) develop CHF during pregnancy (19).

Acute severe valve regurgitation is poorly tolerated. It is important to note that valve regurgitation worsens during pregnancy in some patients. Pharmacological treatment is required to reduce fluid overload. Although interventional treatment is recommended before pregnancy, it may be performed during pregnancy in cases of acute severe valve regurgitation with signs of CHF that cannot be controlled with medication. It is important to emphasize that, when the fetus is sufficiently mature, termination of pregnancy is recommended first, followed by surgical cardiac treatment.

For women of reproductive age who are planning pregnancy and have heart valve disease, the choice of valve is crucial. Although mechanical valves have excellent hemodynamic properties and are durable, their implantation requires long-term anticoagulant therapy, which increases the risk of complications for both the pregnant woman and the fetus (20). The risk of complications, including thromboembolism, bleeding, miscarriage, and preterm delivery, is high during pregnancy in women with a mechanical valve who require anticoagulant therapy.

The use of VKAs is associated with a risk of embryopathy during the first trimester, which depends on the VKA dose (21). In contrast, the risk of complications with an implanted bioprosthesis that functions well without valve dysfunction is minimal. However, bioprostheses are less durable and are associated with a higher risk of structural valve deterioration. In cases of significant bioprosthetic dysfunction, the risk of complications increases, and there is a greater likelihood that reoperation will be required during pregnancy. Therefore, the decision regarding valve selection in women of reproductive age should be made by a team of cardiologists together with the patient, taking into account all the advantages and disadvantages of the valves.

The issue of anticoagulant therapy should be discussed with all women who are planning pregnancy and have an implanted mechanical heart valve. It is important to emphasize that VKAs are the most appropriate and effective medications for preventing valve thrombosis in pregnant women, but they pose risks to the fetus, including embryopathy and fetopathy. Low molecular weight heparins, which do not cross the placental barrier, pose less risk to the fetus but are associated with a higher risk of valve thrombosis.

Another important consideration is strict adherence to the medication regimen. The ESC recommends continuing VKA therapy until conception. Continuation of VKA therapy may be considered during pregnancy if a low VKA dose is sufficient to achieve the target INR. When VKAs are used during pregnancy, INR should be monitored every 1–2 weeks. When LMWH is administered twice daily, dose adjustment based on anti-Xa factor concentration before drug administration is recommended.

Summary

In modern society, improvements in the treatment of congenital heart diseases and increased patient survival have resulted in a growing number of pregnant women with various cardiovascular diseases, including coronary and hypertensive heart diseases. This group of patients is unique. To select the optimal treatment strategy, the risks to both the pregnant woman and the fetus must be assessed.

Therefore, each individual case requires careful evaluation. Treatment decisions should involve not only specialists from various fields, including an obstetrician-gynecologist, cardiac surgeon, and neonatologist, but also the patient herself.

Publication "Internist" No. 2, 2020

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