XVII Международная студенческая научная конференция Студенческий научный форум - 2025

Relevance. Ebstein's anomaly (EA) is an orphan heart defect that can be detected in both newborn children and adults, depending on anatomical features and clinical manifestations. With a slight displacement of the tricuspid valve (TV) leaf, the diagnosis of EA is often not detected. At the same time, even with a pronounced clinical picture, this heart defect may not be diagnosed for a long time. This is due to the fact that a small number of diagnostic methods and algorithms have been developed for EA, which is why the actual occurrence of this congenital heart defect (CHD) may be much higher. In addition, at the moment there are a small number of options for the treatment and correction of the defect. Therefore, this pathology requires a more detailed study of its anatomical and physiological features in order to develop new adequate methods of diagnosis and treatment and improve existing ones.

Introduction. EA is attributed to CHD, in which the posterior and septal valves of the TV are displaced into the cavity of the right ventricle (RV). This defect is characterized by significant variability of manifestations and has various anatomical and pathophysiological features. Concomitant diseases such as atrial septal defect or conduction disorders are not uncommon. EA can be detected at any age, while at different age periods the clinical picture of the disease will have its own characteristics.

Prevalence. Despite the fact that more than 150 years have passed since the initial description of AE, it remains poorly understood. At the moment, the EA is one of the least studied CHD, which is explained by a fairly low incidence and some difficulties in diagnosis. The incidence of EA, according to available data, is 1:200,000 – less than one percent of cases of CHD in Russia. These data correspond to the frequency of occurrence in the world – about 0.5-1%. If this malformation is observed in the mother, then the probability of having a child with this pathology is 6%, if the disease is in the father, then 0.6% [1]. Probably, there are actually more patients with a slight displacement of the TV, since some of them may be underexamined due to the lack of any clinical picture. For this reason, the statistics may be somewhat underestimated.

Classification. There are several variants of EA classifications, and these classifications differ in different countries of the world. As an example, the classifications adopted in Russia will be considered, as well as, for comparison, variants of the types of EA described in Europe.

According to the data of clinical recommendations in Russia, scientists of the Bakulev Federal State Budgetary Scientific Research Center of the USSR named after A.N. Bakulev, under the guidance of Academician Bokeria L.A., 5 types of AE were identified corresponding to separate stages of formation of the TV and the RV.

Type A. Changes in the heart are minimal. There is a thickening of the distal edge of the flaps. There may be a slight "displacement" of the posterior and septal valves of the TV and a slight "atrialization" of the RV and dilation of the fibrous ring of the TV.

Type B. There is no posterior papillary muscle. The posterior and septal flaps of the TV are attached by short chords to the myocardium, forming an "atrialized" part of the RV. The front flap is thickened and enlarged. The interchordal spaces are reduced.

Type C. Marked decrease in mobility of the posterior and septal flaps of the TV. They are attached to the myocardium on a large surface by short chords. The anterior flap is fused with the anterior papillary muscle and irregular tendon strings connected to the delimiting muscle ring. The main opening of the TV is created by an antero-septal commissure. The "normal" hole is restrictive. A large "atrialized" part of the RV.

Type D.The anterior flap of the TV is connected to the delimiting muscle ring. It, together with the posterior and septal flaps of the TV, forms a true "tricuspid sac". Blood from the atrialized part goes directly to the infundibular department. If possible, mobilization and fenestration of the anterior flap, reconstructive surgery of the TV apparatus according to Carpantler is recommended.

Type E. The fused anterior, posterior and septal flaps of the TV form a "tricuspid sac", which opens more often through a narrow opening in the antero-septal commissure of the TV into the infundibular section of the RV. The posterior and septal flaps are fused to the endocardium of the RV. The myocardium of this zone is thin-walled and does not contract. The anterior flap is fused with a delimiting muscular ring throughout. It is not possible for patients of this group to perform reconstructive operations.

It is important to note that when analyzing the studies conducted in Russia, scientists identified only 3 types of EA:

Type A. There is a dystopia of the septal and posterior valve leaf, the volumetric and functional parameters of the RV do not change.

Type B. The mobility of the anterior flap of the valve is not impaired, most of the RV is atrialized.

Type С. The entire RV is atrialized almost completely, with the exception of only a small infundibular area [2].

As a result of the analysis of the data presented in the world scientific literature, two alternative classifications were identified.

The classification of EA according to Selermayer was based on echocardiographic measurements calculating the ratio of the total area of the right atrium (RA) and atrioventricular zone to the functional area of the RA and left ventricle (LV) of the heart in the final diastole:

1st degree, ratio < 0.5;

2nd degree, ratio 0.5-0.99;

3rd degree, ratio 1-1.49;

4th degree, ratio > 1.5.

An increase in severity, that is, a higher degree is combined with a high mortality rate.

The following types are listed in the Carpentier classification:

Type A – minimal displacement of the attachment point of the septum with a small atrial passage;

Type B – moderate displacement of the place of attachment of the septum with a large location of the atria of the RV;

Type C – significant displacement of the attachment site of the septum and posterior sash with an dyskinetic location of the atria of the RV, limited movement of the anterior sash and short chords;

Type D is a tricuspid bag [3].

Etiology. EA is characterized by valvular and ventricular dysplasia of the right parts of the heart. The etiology of EA is unclear. It is assumed that the formation of this defect is influenced by a number of factors. Both genetic and environmental factors are involved. Most cases appear to be sporadic, although there are reports of affected twins and accidental first-degree relatives with other forms of congenital heart disease. A mouse model was created that includes a specific deletion of Alk3 (a receptor for BMP signaling molecules involved in the formation of heart valves), which quite well mimics the deformation of the TV observed in the EA, and even repeats the pre-excitation of the ventricles, so often observed in the human condition [4].

Exogenous factors affecting the development of this heart malformation include taking lithium and benzodiazepines during pregnancy, as well as past viral infections.

During embryonic development, the valve flaps are normally detached from the myocardium, this is not observed with EA. For the most part, the flaps are soldered to the myocardium, along with this, the position of the TV flaps changes towards the apex of the heart: the septal flap is shifted as much as possible, moderately posterior, minimally anterior. As a result of this displacement of the valves, a pathological change in the valve occurs, for this reason, hemodynamic disorders develop. The severity of these disorders depends on the degree of displacement of the valves of the affected valve and the accompanying displacement of the atrioventricular ring [5].

Pathogenesis. EA is a congenital aberration of the heart characterized by apical displacement of the septum and lower flaps of the TV, as well as elongation of the anterior flap with fenestration holes and attachment of chords. This leads to the formation of the atrial segment of the RV. Thus, the displacement effectively divides the ventricle into two regions: the proximal part to it, which is functionally integrated with the RA, and the distal part to it, which is an effectively functioning RV. The decrease in blood outflow from the right cardiac sections is due to a decrease in the contractility of the RV and widespread tricuspid regurgitation. Due to the absence of a valve between the anatomical RA and the RV, ineffective blood flow between these chambers is observed during their sequential contraction. This is especially true for the RV, since the myocardium of this area is often weakened, which can lead to lower dyskinesia.

Blood bypass surgery from right to left is often accompanied by arterial desaturation, which is due to low efficiency and abnormal blood flow, as well as the presence of an atrial septal defect. As a result of these structural abnormalities, the RV and the RA increase significantly in size, which can be observed even in young children. An increase in the ventricles leads to an increase in atrial defect and an increase in heart mass, often accompanied by swelling of the liver and lungs [6].

A malformation of the valve leads to regurgitation of the blood, which contributes to its return to the RA. This disorder, characterized by varying degrees of blood flow turbulence, ultimately contributes to hypertrophy of the heart muscle, the development of RV failure and is often accompanied by swelling of the liver and lungs [7, 8, 9].

An additional aspect of EA in progressive stages, this expansion of the RV can contribute to the displacement of the interventricular septum to the left and have a compression effect on the cavity of the LV [7].

Thus, pronounced dilation leads to narrowing of the chamber of the LV, which on the echocardiogram manifests itself in the shape of a crescent, and causes heart failure due to obstruction of the outlet tract of the LV. According to statistics, this option is observed in more than 2/3 of patients with EA [7].

In the context of hemodynamic disorders, a number of problems arise related to the rhythm of the heart. One of the most interesting aspects is the high incidence of additional atrioventricular pathways (AVP) – such as Wolf-Parkinson-White syndrome (in about 15-20% of patients) – which tend to cluster along the interventricular septum and the posterior part of the true atrioventricular ring. However, their location is characterized by a high degree of variability. This localization, characterized by an abnormal structure of the valve tissue, indicates a possible connection between the deformation of the valve and the development of additional pathways, due to the presence of connective tissue strands in the normal location of the conductive pathways. [10].

In addition, it is becoming increasingly apparent that the additional AVP observed in patients with EA are more difficult to catheter ablation compared to AVP found in structurally normal hearts, which is due to the significant variability of their location. This observation suggests the presence of unique anatomical or functional features of both the additional pathways themselves and the surrounding tissues in hearts with EA. The significant variability of the topic of additional conductive pathways causes the complexity of catheter ablation, since the doctor should not affect anatomically correctly positioned conductive pathways during the procedure.

Atrial fibrillation can also be observed, the frequency of which increases with age. The percentage of patients who eventually develop atrial tachyarrhythmias reaches 30-40% [11].

In a 2013 study by G.E. Assenza et al. it was found that a significant majority of patients with EA (from 71% to 94%) have complete blockage of the right leg of the Gis bundle. This is due to the lack of pre-excitation due to congenital anomalies in the right branch of the Gis bundle, which is accompanied by delayed conduction and an increase in activation time in the atrial tissue of the RV, because the excitation occurs by a different mechanism: the transmission of an impulse occurs from one cardiomyocyte to another. It is this mechanism that underlies the delay of the pulse, which can often be recorded on an electrocardiogram. [12].

In EA, common concomitant heart diseases also include defects of the atrial and interventricular septa and an open arterial duct. They may have a compensatory and adaptive role, which consists in unloading the right parts of the heart. One of the pathological predictors is a large deformation of the base and apex resulting from longitudinal deformation of the heart [12].

Clinical manifestations. The clinical picture of the disease in patients demonstrates variability due to the heterogeneity of the anatomical and physiological characteristics of the pathological process. It is important to note that, despite the fact that in most cases the diagnosis is made in infancy or childhood, the primary detection of the disease is also possible in adult patients. Rarely, the diagnosis of EA can be established even in the prenatal period. If EA is diagnosed at an early age or in utero, then, as a rule, the TV is significantly displaced and significant hemodynamic disorders may occur. Depending on the age of the patient, the clinical manifestations will have some peculiarities [13].

In newborns with EA, cyanosis is observed due to reduced oxygen levels in the blood, as well as congestive heart failure of the RV caused by TV dysfunction. In addition, there is significant cardiomegaly associated with dilation of the right heart and arrhythmias. Cyanosis is often accompanied by severe heart failure or right-left bypass surgery. Symptoms can range from mild to extremely severe.

If a newborn is diagnosed with pulmonary hypertension, the risk of developing cyanosis increases significantly, since this condition further restricts pulmonary blood flow and oxygenation. This, in turn, contributes to an increase in pressure in the RV and the occurrence of RV failure. As a result, hepatomegaly and gradual expansion of the heart may occur [13].

In infancy and adolescence, the clinical picture is usually characterized by the presence of symptoms such as cough, stunted growth, exhaustion, rapid and difficult breathing, shortness of breath and tachycardia. These manifestations may be due to insufficiency of the RV and a decrease in the ejection fraction of the LV, which leads to an increase in heart rate in response to the metabolic needs of the body. All these factors ultimately depend on changes in hemodynamics.

The clinical phenotype of patients with EA is determined by a complex of factors, including the age of manifestation of symptoms, the degree of tricuspid regurgitation, the size and volume of the RV, as well as the presence and severity of atrial bypass surgery between the RA and LA. Most patients with this defect live to adulthood, however, some of them may develop progressive RV failure. With a slight displacement of the TV and the absence of any clinical manifestations, the diagnosis may not be diagnosed at all [14].

Diagnosis and evaluation. The basic examination of patients with EA includes electrocardiography, chest X-ray, daily Holter monitoring, echocardiography and, if necessary, cardiopulmonary stress testing. In addition, magnetic resonance imaging of the heart can be prescribed to quantify the size and function of the RV.

During electrocardiography, deviations from the reference values are recorded in a significant part of patients. Among them, the most common are lengthening of the PQ interval, an increase in amplitude and expansion of the P, as well as changes in the QRS complex. This study allows us to identify various concomitant cardiac conduction disorders, such as Wolf-Parkinson-White syndrome, atrial fibrillation, blockage of the right leg of the Gis [15].

An X-ray examination of the chest of a patient with clinical manifestations of EA is characterized by pronounced cardiomegaly, in which the contours of the heart occupy almost the entire chest. In some cases, in newborns with severe symptoms, the cardiothoracic index can reach a value equal to one [16].

Transthoracic echocardiography is a reference imaging method in the field of EA and serves as the main study for determining the parameters of the right heart, including the size of the atria and ventricles, as well as for the dynamic assessment of intracardiac shunts and concomitant cardiac pathologies. This method of investigation allows the most accurate visualization of pathological changes in the TV. Color flow dopplerography plays a key role in evaluating tricuspid regurgitation [16].

Magnetic resonance imaging of the heart, performed using a gadolinium-based contrast agent, provides an opportunity to quantify the volume of the RV and the degree of tricuspid regurgitation [17]. However, this research method is not as widely used as transthoracic echocardiography, and is rarely prescribed to patients for the purpose of primary diagnosis.

Surgical correction of the defect. Currently, indications for surgical correction of EA include significant hemodynamic disorders, which are observed, as a rule, with a significant displacement of the TV towards the apex of the heart. At the moment, there are two options for correcting this heart defect: prosthetics with an artificial prosthesis and various methods of plastic surgery of a pathologically altered valve. Preference should be given to the technique of TV surgery, which will maximize the preservation of heart tissue.

The main task of the surgical intervention is the reconstruction of the TV. As part of this procedure, the following manipulations are usually performed: plication of the RV, reduction of the volume of the RA and either closure of the atrial septum or subtotal closure. In cases where the function of the RV is significantly impaired, a ventricular unloading procedure can be applied by means of bidirectional cavopulmonary bypass [18].

Danielson's original technique involves modifying the true tricuspid ring, including removing the atrial part of the free wall of the RA, as well as reducing the size of the RA.

Subsequent modifications by Danielson include the integration of the anterior papillary muscle with the interventricular septum using a Sebening suture, which improves the interface of the flap with the interventricular septum [19].

Conclusion. Based on the analysis of data from the world and domestic literature, it can be concluded that the Ebstein anomaly has not been sufficiently studied. EA is a rare congenital malformation of the heart, the main anatomical feature of which is an abnormal structure of the TV with its displacement into the cavity of the RV, often combined with an atrial septal defect or cardiac conduction disorders. In different countries of the world, the classification of this defect varies, which may cause difficulties in making an accurate diagnosis. The degree of TV displacement and the severity of clinical manifestations correlate, which makes it difficult to diagnose in the early stages in patients with minor valve displacement. In addition, there is a high variability of clinical manifestations in different age groups, which is due to a number of factors. The etiology of EA has not been reliably established at the moment, which is why it is impossible to carry out preventive measures at the early stages of fetal development. The pathogenesis of this pathology has been studied somewhat better and is mainly associated with an abnormal location of the TV, as a result of which an atrialized part of the RV is formed, which leads to ineffective blood flow and, with further progression of the defect, various severe hemodynamic disorders may occur. The main method of diagnosing EA is transthoracic echocardiography, as this method provides the best visualization of CHD. In patients with cardiac conduction disorders, an electrocardiographic examination should be performed. Surgical treatment of the defect is indicated only for patients with severe hemodynamic disorders, while various techniques can be used, however, preference should be given to TV plastic surgery rather than its prosthetics.

List of literature

1. Fahed AC, Gelb BD, Seidman JG, Seidman CE. Genetics of congenital heart disease: the glass half empty. Circ Res. 2013. vol. 112, no. 4. P. 707-720. doi: 10.1161/CIRCRESAHA.112.300853. Erratum in: Circ Res. 2013 Jun 7;112(12):e182. PMID: 23410880; PMCID: PMC3827691.

2. Абралов Х. К., Алимов А. Б. Диагностика и хирургическое лечение аномалии Эбштейна // Вестник Национального медико-хирургического Центра им. Н. И. Пирогова. 2016. №1. URL: https://cyberleninka.ru/article/n/diagnostika-i-hirurgicheskoe-lechenie-anomalii-ebshteyna (дата обращения: 12.12.2024).

3. Chauvaud S, Berrebi A, d'Attellis N, Mousseaux E, Hernigou A, Carpentier A. Ebstein's anomaly: repair based on functional analysis. Eur J Cardiothorac Surg. 2003. vol. 23, no 4. P. 525-531. doi: 10.1016/s1010-7940(02)00836-9. PMID: 12694771.

4. Edward P. Walsh, Ebstein’s Anomaly of the Tricuspid Valve: A Natural Laboratory for Re-Entrant Tachycardias. JACC: Clinical Electrophysiology. 2018. Vol. 4. P. 1271-1288. ISSN 2405-500X, doi.org/10.1016/j.jacep.2018.05.024.

5. Делягин В. М. АНОМАЛИЯ ЭБШТЕЙНА (ЭХОКАРДИОГРАФИЧЕСКИЕ И АНАТОМИЧЕСКИЕ ПАРАЛЛЕЛИ) // Педиатрический вестник Южного Урала. 2020. №1. URL: https://cyberleninka.ru/article/n/anomaliya-ebshteyna-ehokardiograficheskie-i-anatomicheskie-paralleli (дата обращения: 12.12.2024).

6. Cabrera R, Miranda-Fernández MC, Huertas-Quiñones VM, Carreño M, Pineda I, Restrepo CM, Silva CT, Quero R, Cano JD, Manrique DC, Camacho C, Tabares S, García A, Sandoval N, Moreno Medina KJ, Dennis Verano RJ. Identification of clinically relevant phenotypes in patients with Ebstein anomaly. Clin Cardiol. 2018. vol. 41, no. 3. P. 343-348. doi: 10.1002/clc.22870. Epub 2018 Mar 22. PMID: 29569399; PMCID: PMC6489938.

7. Malhotra A, Agrawal V, Patel K, Shah M, Sharma K, Sharma P, Siddiqui S, Oswal N, Pandya H. Ebstein's Anomaly: "The One and a Half Ventricle Heart". Braz J Cardiovasc Surg. 2018. vol. 33, no. 4. P. 353-361. doi: 10.21470/1678-9741-2018-0100. PMID: 30184032; PMCID: PMC6122759.

8. Holst KA, Connolly HM, Dearani JA. Ebstein's Anomaly. Methodist Debakey Cardiovasc J. 2019. vol. 15, no. 2. P. 138-144. doi: 10.14797/mdcj-15-2-138. PMID: 31384377; PMCID: PMC6668741.

9. Connolly HM, Dearani JA, Miranda WR. Ebstein Anomaly: We Should Do Better. J Am Coll Cardiol. 2023. vol. 81, no. 25. P. 2431-2433. doi: 10.1016/j.jacc.2023.05.009. PMID: 37344045.

10. Khositseth A, Danielson GK, Dearani JA, Munger TM, Porter CJ. Supraventricular tachyarrhythmias in Ebstein anomaly: management and outcome. J Thorac Cardiovasc Surg. 2004. vol. 128, no. 6. P. 826-833. doi: 10.1016/j.jtcvs.2004.02.012. PMID: 15573066.

11. Mavroudis C, Stulak JM, Ad N, Siegel A, Giamberti A, Harris L, Backer CL, Tsao S, Dearani JA, Weerasena N, Deal BJ. Prophylactic atrial arrhythmia surgical procedures with congenital heart operations: review and recommendations. Ann Thorac Surg. 2015. vol. 99, no. 1. P. 352-359. doi: 10.1016/j.athoracsur.2014.07.026. Epub 2014 Nov 15. PMID: 25442995.

12. Tarando F, Coisne D, Galli E, Rousseau C, Viera F, Bosseau C, Habib G, Lederlin M, Schnell F, Donal E. Left ventricular non-compaction and idiopathic dilated cardiomyopathy: the significant diagnostic value of longitudinal strain. Int J Cardiovasc Imaging. 2017. vol. 33, no. 1. P. 83-95. doi: 10.1007/s10554-016-0980-3. PMID: 27659478.

13. Thareja SK, Frommelt MA, Lincoln J, Lough JW, Mitchell ME, Tomita-Mitchell A. A Systematic Review of Ebstein's Anomaly with Left Ventricular Noncompaction. J Cardiovasc Dev Dis. 2022. vol. 9, no. 4. P. 115. doi: 10.3390/jcdd9040115. PMID: 35448091; PMCID: PMC9031964.

14. Farhan M, Prajjwal P, Sai VP, Aubourg O, Ushasree T, Flores Sanga HS, Fadhilla ADD, Marsool MDM, Nahar N, Ghosh S. Neurological, Extracardiac, and Cardiac Manifestations of Ebstein's Anomaly Along With its Genetics, Diagnostic Techniques, Treatment Updates, and the Future Ahead. Cureus. 2023.vol. 15, no. 2. P. e35115. doi: 10.7759/cureus.35115. PMID: 36945291; PMCID: PMC10024951.

15. Stout KK, Daniels CJ, Aboulhosn JA, Bozkurt B, Broberg CS, Colman JM, Crumb SR, Dearani JA, Fuller S, Gurvitz M, Khairy P, Landzberg MJ, Saidi A, Valente AM, Van Hare GF. 2018 AHA/ACC Guideline for the Management of Adults With Congenital Heart Disease: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol. 2019. vol. 73, no. 12. P. 81-192. doi: 10.1016/j.jacc.2018.08.1029. Epub 2018 Aug 16. Erratum in: J Am Coll Cardiol. 2019 May 14;73(18):2361-2362. doi: 10.1016/j.jacc.2019.03.018. PMID: 30121239.

16. Holst KA, Connolly HM, Dearani JA. Ebstein's Anomaly. Methodist Debakey Cardiovasc J. 2019. vol. 15, no. 2. P. 138-144. doi: 10.14797/mdcj-15-2-138. PMID: 31384377; PMCID: PMC6668741.

17. Attenhofer Jost CH, Edmister WD, Julsrud PR, Dearani JA, Savas Tepe M, Warnes CA, Scott CG, Anavekar NS, Ammash NM, Connolly HM. Prospective comparison of echocardiography versus cardiac magnetic resonance imaging in patients with Ebstein's anomaly. Int J Cardiovasc Imaging. 2012. vol. 28, no. 5. P. 1147-1159. doi: 10.1007/s10554-011-9923-1. Epub 2011 Aug 6. PMID: 21822629.

18. Raju V, Dearani JA, Burkhart HM, Grogan M, Phillips SD, Ammash N, Pike RP, Johnson JN, O'Leary PW. Right ventricular unloading for heart failure related to Ebstein malformation. Ann Thorac Surg. 2014. vol. 98, no. 1. P. 167-173. doi: 10.1016/j.athoracsur.2014.03.009. Epub 2014 May 6. PMID: 24811983.

19. Carpentier A, Chauvaud S, Macé L, Relland J, Mihaileanu S, Marino JP, Abry B, Guibourt P. A new reconstructive operation for Ebstein's anomaly of the tricuspid valve. J Thorac Cardiovasc Surg. 1988. vol. 96, no. 1. P. 92-101. PMID: 3386297.

Код для цитирования: Скопировать