Chronic heart failure in pregnancy

According to the WHO definition, heart failure in pregnancy is the inability of the heart to supply blood to the body's tissues in accordance with metabolic needs at rest and/or during moderate physical activity. The main manifestations of heart failure are decreased exercise tolerance and fluid retention in the body.

Heart failure (HF) is a natural and most severe complication of various diseases of the cardiovascular system (congenital and acquired heart defects, ischemic heart disease, acute myocarditis and cardiomyopathy, infective endocarditis, arterial hypertension, cardiac arrhythmia and conduction disorders).

The development and progression of heart failure during pregnancy are based on two interrelated pathophysiological mechanisms: cardiac remodeling (which is understood as a set of changes in the shape and size of the cavity and mass of the ventricles, as well as the structure, ultrastructure and metabolism of the myocardium) and activation of neurohumoral systems, primarily the sympathoadrenal (SAS), renin-angiotensin (RAS), endothelin and vasopressin.

Pregnancy contributes to the development and progression of heart failure, which is caused by significant changes in hemodynamics (increase in BCC, heart rate, total peripheral resistance, appearance of additional placental circulation), acceleration of metabolic processes, pronounced endocrine and neurohumoral shifts. Most often, the onset and increase of heart failure occur at 26-32 weeks of pregnancy, that is, during the period of maximum hemodynamic load, as well as in the postpartum period.

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Symptoms of Heart Failure During Pregnancy

The clinical symptoms of heart failure during pregnancy are varied. They include signs indicating decreased tolerance to physical activity and fluid retention in the body. Dyspnea, acrocyanosis, cardiac asthma indicate congestion in the pulmonary circulation; in the systemic circulation - liver enlargement, swelling and pulsation of the jugular veins, ascites, edema, nocturia.

Acute heart failure - pulmonary edema

Acute heart failure during pregnancy is a serious threat to the life of the pregnant woman and the woman in labor. Most often, it develops as left ventricular failure - cardiac asthma or pulmonary edema.

Pulmonary edema is an acute increase in pulmonary hydration due to the penetration of fluid from the capillaries into the interstitial tissue and alveoli, leading to a disruption of their ventilation.

The pathophysiological mechanisms of pulmonary edema development are:

• increase in hydrostatic pressure in the pulmonary capillaries;
• decrease in blood oncotic pressure;
• increased permeability of alveolar-capillary membranes;
• disruption of lymphatic drainage of lung tissue.

The first mechanism develops cardiogenic pulmonary edema (that is, left heart failure itself), the other three are characteristic of non-cardiogenic pulmonary edema.

Pregnancy in sick women significantly increases the risk of pulmonary edema, which is associated with the peculiarities of hemodynamics (significant increase in BCC) and neurohumoral mechanisms of regulation, a tendency to fluid and sodium retention, dysfunction of cell membranes, constant psychoemotional stress, relative hypoproteinemia leading to a decrease in the oncotic pressure of the blood, and insufficient lymph outflow associated with mechanical factors, in particular with the high position of the diaphragm.

Cardiogenic pulmonary edema is the most common variant, which is the result of acute failure of the left heart, which occurs with various cardiac pathologies, acquired and congenital heart defects, acute myocarditis, cardiomyopathy, large-focal cardiosclerosis, arterial hypertension, etc. Most often, pulmonary edema in pregnant women develops with mitral stenosis, the main pathogenetic factor in the development of which is hypervolemia.

There are four stages of development of pulmonary edema:

• Stage I - only peribronchial edema is observed;
• Stage II - fluid accumulates in the interalveolar septa;
• II (stage - fluid seeps into the alveoli;
• IV (final) stage - the volume of interstitial fluid increases by more than 30% from the initial level and it appears in the large bronchi and trachea.

According to these stages, interstitial (clinically manifested by cardiac asthma) and alveolar pulmonary edema are diagnosed. Rapid and massive fluid leakage into the alveoli leads to "lightning" pulmonary edema, which is accompanied by asphyxia and often ends in death. According to etiology, rheumatic and non-rheumatic myocarditis are distinguished; the latter can be infectious - bacterial, viral, parasitic and with other diseases.

Non-rheumatic myocarditis is a consequence of the direct or indirect action of infection through the mechanism of allergy or autoimmunization of an infectious or non-infectious factor (medicines, serum, food products, etc.) on the myocardium.

Cardiosclerosis (myocardial fibrosis) is the final stage of various heart diseases: myocarditis (myocarditic cardiosclerosis), atherosclerosis of the coronary vessels (atherosclerotic cardiosclerosis), myocardial infarction (postinfarction cardiosclerosis). Myocarditic cardiosclerosis (myocardial fibrosis) is predominantly found in pregnant women.

The diagnosis of myocarditis in pregnant women is established on the basis of clinical data (shortness of breath, palpitations, pain in the heart, limitation of physical activity, arrhythmia, heart failure is recognized), electro- and echocardiographic studies.

Indications for termination of pregnancy are:

• acute myocarditis;
• cardiosclerosis with severe rhythm disturbances;
• CH stage IIA and higher;
• III-IV FC;
• signs of coronary pathology.

The scope of treatment measures for myocarditis: treatment of foci of chronic infection, NSAIDs, antibiotics, glucocorticosteroids (if there is no effect from NSAIDs), desensitizing agents, metabolic drugs, beta-blockers.

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Classification of heart failure in pregnancy

The classification of heart failure during pregnancy, approved by the VI National Congress of Cardiologists of Ukraine (2000), includes the definition of the clinical stage, functional class and variant.

Clinical stages of heart failure (corresponds to the stage of chronic circulatory failure according to the classification of N.D. Strazhesko, V. Kh. Vasilenko):

• CH I - latent, or initial;
• CH II - pronounced (divided into IIA - the beginning of a prolonged stage and IIB - the end of this stage);
• CH III - terminal, dystrophic.

The stage of heart failure during pregnancy reflects the stage of clinical evolution of this process, while the functional class of the patient is a dynamic characteristic that can change under the influence of treatment.

According to the NYHA criteria, four functional classes (FC) of the patient are distinguished:

• I FC - a patient with heart disease tolerates normal physical activity without shortness of breath, fatigue or palpitations;
• II FC - a patient with moderate limitation of physical activity, who experiences shortness of breath, fatigue, and palpitations when performing normal physical activity;
• III FC - there is a significant limitation of physical activity, there are no complaints at rest, but even with minor physical exertion, shortness of breath, fatigue, and palpitations occur;
• IV FC - at any level of physical activity and at rest, the indicated subjective symptoms occur.

Most pregnant women with heart disease belong to FC I and II, less than 20% of patients belong to FC III and IV.

Variants of heart failure: with systolic dysfunction - systolic HF (ejection fraction, EF<40%), with preserved systolic function - diastolic HF (EF>40%).

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Diagnosis of heart failure during pregnancy

Diagnosis of heart failure during pregnancy is based on clinical signs, data from instrumental research methods that allow for the objectification of myocardial dysfunction and cardiac remodeling (echocardiography with Doppler, ECG and radiography), as well as positive results of treatment aimed at eliminating circulatory disorders.

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Delivery of pregnant women with heart failure

The presence of heart failure stage IIA and higher, III and IV FC, regardless of the nature of the heart disease, necessitates a gentle method of delivery: in uncomplicated cases - stopping pushing with the help of an operation to apply obstetric forceps, and in an unfavorable obstetric situation (breech presentation, narrow pelvis) - delivery by cesarean section.

In case of CH IIB and CH III stage, it is mandatory to stop lactation; in case of CH IIA, night feeding is usually excluded.

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Treatment of heart failure during pregnancy

Treatment of chronic heart failure in pregnant women includes:

• limitation of load: for heart failure IIA - semi-bed rest and moderate physical activity ("comfortable" motor modes); for heart failure IIB and heart failure III - bed rest and breathing exercises in bed;
• therapy for the underlying disease that caused heart failure;
• a diet with limited fluid and sodium chloride intake (less than 3 g/day for I-II FC and less than 1.5 g/day for III-IV FC).

Drug therapy

During pregnancy, the most commonly used angiotensin-converting enzyme inhibitors in cardiology clinics for the treatment of heart failure are strictly contraindicated. Drugs in this group cause growth retardation, limb contractures, skull and lithotripsy, pulmonary hypoplasia, oligohydramnios, and even antenatal death in the fetus. In addition to the direct negative impact on the fetus, they lead to spasm of the uteroplacental vessels, further aggravating the suffering of the fetus.

Angiotensin II receptor blockers are also strictly contraindicated throughout pregnancy.

For the treatment of CHF in pregnant women, drugs from various groups are used:

• diuretics for obvious clinical signs of fluid retention in the body; the drug of choice is furosemide (40 mg/day 2-3 times a week);
• cardiac glycosides (digoxin 0.25-0.50 mg/day) are prescribed for tachystolic atrial fibrillation. Heart failure stage IIA and higher, FC III-IV;
• Peripheral vasodilators are used for heart failure with signs of pulmonary congestion: molsidomine 3-8 mg 3 times a day (contraindicated in the first trimester);
• Beta-blockers are prescribed to all patients with CHF FC II-IV, starting with the minimum dose, gradually increasing it weekly to the target dose: metoprolol or atenolol (from 6.25 to 50 mg), carvedilol (from 3.125 to 25 mg), bisoprolol (from 1.25 to 10 mg), nebivolol (from 1.25 to 10 mg). When prescribing beta-blockers, it should be remembered that they increase the tone of the uterus and, in case of threatened termination of pregnancy, can cause miscarriage; they also reduce uteroplacental blood flow. One of the proven negative consequences of the use of beta-blockers during pregnancy is fetal growth retardation. Considering that beta-blockers can cause bradycardia and hypotension in the newborn, they should be discontinued 48 hours before delivery;
• agents that normalize myocardial metabolism: riboxin (0.2 g 3 times a day), vitamins, potassium orotate (0.25-0.5 g 3 times a day), trimetazidine (20 mg 3 times a day).

In the treatment of heart failure in pregnant women with diastolic dysfunction of the left ventricle, verapamil and beta-blockers are used. Cardiac glycosides, diuretics, and nitrates (prescribed for the systolic variant of heart failure) should be avoided (or used very sparingly).