Fetal and neonatal arrhythmias (clinical picture, diagnosis, treatment)

The dissertation is devoted to a comprehensive study of fetal and neonatal cardiac rhythm and conduction disturbances. The author systematizes data on the prevalence of various types of arrhythmias in the fetus and newborn, analyzes morphometric changes in the heart and features of hemodynamics in sinus rhythm disturbances, extrasystole, supraventricular tachyarrhythmias, and blocks of organic origin, as well as risk factors for their occurrence.

Particular attention is paid to the development of algorithms for the examination and treatment of fetuses and newborns with rhythm disturbances, including malignant forms associated with fetal hydrops and circulatory failure. The work is based on extensive clinical material comprising cases of fetal and postnatal arrhythmias and combines a retrospective analysis with an assessment of the outcomes of intrauterine therapy. The practical significance of the study is associated with the introduction of the proposed protocols into the activities of perinatal and cardiac surgery centers.

Fetal rhythm disturbances are recorded in 1–5% of all pregnancies (Ferrer PL, 1998). Approximately 10% of all arrhythmias are accompanied by the development of hydrops and intrauterine mortality (McCurdy CM, Reed KL, 1995). The diagnosis and treatment of fetal rhythm disturbances is an interdisciplinary problem that has not been fully resolved to date. Malignant types of arrhythmias (supraventricular tachycardia, atrial flutter, complete atrioventricular block) combined with fetal hydrops are the cause of intrauterine death in 3–30% of cases. Transient arrhythmias (single ventricular and atrial extrasystoles, sinus tachycardia) occur, according to Copel JA, 1986, and Deal BJ, 1998, in 15–32% of cases and do not require specific treatment. According to Strasburger JF, 2000, supraventricular tachycardia and complete block are diagnosed in 1 of 5000 fetuses. According to Ferrer PL, 2000, complete AV block is detected in 1:20,000 live-born children; the same author suggests a twofold increase in the number of fetuses with this pathology due to the high probability of intrauterine death. Atrial flutter occurs in 30–46% of all cases of fetal tachyarrhythmias. The absence of global statistics on cases of fetal arrhythmias is due primarily to the difficulties in identifying the very fact of the presence of this cardiac pathology. It should be emphasized that routine examination of the pregnant woman and auscultation of the fetal heart play the leading role as a screening method for the diagnosis of fetal arrhythmia. More than half of all fetal rhythm disturbances are diagnosed in the third trimester of pregnancy. On the one hand, this indicates the possibility of long-term compensation of the existing pathology; on the other, it is explained by the more frequent visits of the woman to the doctor at this gestational age. The detection of fetal arrhythmia in early pregnancy is associated with a high risk of intrauterine death.

The main method for diagnosing normal and pathological conditions of the fetal heart remains ultrasound examination. Various modes make it possible in most cases to differentiate atrial and ventricular contractions, determine the heart rate, detect the presence of fetal hydrops, and monitor the adequacy of the therapy administered. Currently, ultrasound is the most accessible, readily performed, and sufficiently informative method for the diagnosis of fetal arrhythmias.

One of the main problems in fetal arrhythmology is fetal hydrops. According to most authors, fetal hydrops complicates the course of supraventricular tachycardia and atrial flutter in almost half of the cases. The presence of circulatory failure in the fetus is a prognostically unfavorable factor, both in terms of survival and therapy outcomes. The rate of progression of hydrops depends on the degree of circulatory failure and, importantly, on gestational age.

The etiological factor of fetal arrhythmia is not identified in most cases. However, there are certain features of the fetal heart that may contribute to the development of rhythm disturbances. A number of congenital heart defects (especially those affecting the area of the atrioventricular groove) may be combined with fetal arrhythmias.

At present, there are no developed methods and algorithms for the examination and treatment of fetuses with cardiac rhythm and conduction disturbances.

Neonatal arrhythmias present certain difficulties both in terms of diagnosis and treatment. Children in the first three years of life, due to age-related characteristics, are often unable to clearly formulate their complaints and represent the most complex category of patients with regard to the use of modern high-tech diagnostic methods. In such patients, a number of examinations cannot be performed for technical reasons; for example, high-resolution electrocardiography and the 20-minute heart rate variability assessment method require compliance with a number of conditions (low noise level, complete rest) that are simply unattainable due to age characteristics. As a consequence, there are no clear criteria and indications for drug and surgical treatment of the disease and for preventive measures.

The malignant nature of a number of cardiac rhythm and conduction disturbances in fetuses and newborn children requires the development of algorithms for examination and treatment. At present, unified treatment protocols for young patients with organic tachyarrhythmias have not been adopted in our country.

Taking the above into account, we consider it important to devote the study to addressing these problems.

Aim of the study

The aim of the study is to identify the spectrum of fetal and neonatal cardiac rhythm and conduction disturbances, determine their possible causes, and develop methods of diagnosis, treatment, and assessment of outcomes.

To achieve this aim, the following tasks were solved.

Tasks of the study

1. To identify the spectrum of fetal rhythm disturbances, etiological factors of their occurrence, and methods of diagnosis.

2. To determine morphometric changes in fetal cardiac parameters depending on the type of arrhythmia.

3. To develop optimal options for the treatment of fetal arrhythmias depending on their nature, the presence of concomitant pathology, and the time of onset. To determine the relationship between intrauterine therapy of arrhythmias and the probability of postnatal occurrence of rhythm disturbances in the studied group of newborns.

4. To analyze possible risk factors for the occurrence of fetal and neonatal cardiac rhythm and conduction disturbances.

5. To determine the structure of cardiac rhythm disturbances, possible causes of their occurrence, treatment options, and prognosis of arrhythmias in newborn children.

Scientific novelty.

For the first time in our country, a systematic study devoted to the problem of fetal arrhythmias and the possible causes of their occurrence has been carried out. Algorithms for the examination and treatment of cardiac rhythm and conduction disturbances in human fetuses have been developed.

For the first time in our country, an assessment of changes in the morphometric parameters of the human fetal heart in the presence of arrhythmia and after treatment has been performed.

In this study, for the first time, a prognostic assessment of the causes and factors contributing to the occurrence of fetal and neonatal arrhythmias is given.

Algorithms for the examination and treatment of children with supraventricular tachycardia, as the most frequent type of arrhythmia accompanied by hemodynamic disturbance and life-threatening, have been identified and developed. A prognostic assessment of "favorable" forms of neonatal arrhythmias is provided.

Practical significance.

The work performed will expand the capabilities of comprehensive echocardiography in the prenatal detection of various types of cardiac rhythm and conduction disturbances.

The study will introduce into practice algorithms for the examination and treatment of fetuses with malignant types of arrhythmias.

The development of algorithms for the examination and treatment of fetal arrhythmias will allow an adequate assessment of the fetal condition and should contribute to a more reasoned decision on the advisability of maintaining pregnancy, and to addressing the question of the possibility and necessity of prolonging pregnancy. These schemes can serve as the basis for conducting a perinatal consultation in the diagnosis of fetal cardiac rhythm and conduction disturbance.

Assessment of possible risk factors for the occurrence of cardiac rhythm and conduction disturbances will make it possible to identify a probable risk group among pregnant women who require more detailed and thorough examination and follow-up.

The development of algorithms for the examination and treatment of malignant arrhythmias in newborn children will contribute to the standardization of approaches to this disease and will make it possible to define indications for the surgical treatment of this pathology.

Implementation of the results of the work into practice and publications

The results of the work have been implemented in the practice of the Department of Pathology of Newborn and Premature Infants of the Perinatal Medical Center at City Clinical Hospital No. 67 of the Moscow Department of Health, and of the Perinatal Cardiology Center of the A.N. Bakulev Scientific Center for Cardiovascular Surgery.

The results of this work were presented at the Congress of Cardiovascular Surgeons in 2001, 2003, 2004, 2005; at the Congresses "Pediatric Cardiology 2004," "Pediatric Cardiology 2006," "Pediatric Cardiology 2010"; at the All-Russian Congress of Cardiologists in 2010; and at the Assembly "Health of the Capital — 2010." In 2006, the author was awarded the first prize of the competition for young scientists at the All-Russian Congress "Pediatric Cardiology 2006" for the scientific report "Fetal arrhythmias: problems of diagnosis and treatment." In 2010, as part of a team of physicians, she received the "Privation" (Calling) Prize for "the creation of a new direction in medicine": "System for providing highly specialized interdisciplinary care to pregnant women and children with cardiovascular pathology."

The materials of the dissertation form the basis of a lecture course on fetal arrhythmias in the advanced training course for ultrasound diagnostics physicians and obstetrician-gynecologists at the Perinatal Cardiology Center of the Bakulev Scientific Center for Cardiovascular Surgery.

Nineteen publications have been issued based on the materials of the study.

Volume and structure of the dissertation: The dissertation is set out on 421 typewritten pages and consists of an introduction, a review of the literature, two chapters and five parts of the original research with a discussion of the results obtained, a conclusion, conclusions, practical recommendations, and an appendix. The bibliography includes 465 sources, of which 190 are domestic and 275 are foreign. The work is illustrated with 62 tables, 39 figures, 10 schemes, and 10 clinical examples.