Ebstein's anomaly

Overview

Ebstein's abnormality is a tricuspid valve malformation associated with RV myopathy that has a wide range of anatomic and pathophysiologic characteristics, resulting in a wide range of clinical outcomes. For asymptomatic individuals, medical care and observation is frequently suggested, and it can be effective for many years.

The purpose of operational surgery is to restore the tricuspid valve; this usually entails RV plication, right atrial reduction, and atrial septal closure or subtotal closure. In terms of degree of RV enlargement, RV dysfunction, RV fractional area change, and tricuspid valve regurgitation, postoperative functional tests often show an improvement or relative stability.

 

Ebstein anomaly definition

The Ebstein anomaly of the tricuspid valve is a congenital abnormality in which the insertion of the septal and posterior leaflets are displaced downward. In most cases, only the anterior leaflet is damaged. The leaflets of the tricuspid valve are malformed. Poor coaptation of the valve leaflets as a result of the displacement generates tricuspid regurgitation, which causes right atrial enlargement to varying degrees depending on the severity of the tricuspid regurgitation.

 

Epidemiology

Ebstein abnormality is thought to account for 0.5 percent of congenital heart disease cases. Because mild versions are commonly untreated, the true prevalence is unknown. More cases are being diagnosed as a result of the widespread use of echocardiography. Ebstein anomaly is more common in white females' infants. There is no definite sex predominance, though.

Ebstein anomaly can present at various stages of life, as follows:

  • Fetal life: The Ebstein anomaly is frequently discovered by chance during an echocardiogram.
  • Neonatal life and infancy: Cyanosis and/or severe heart failure are common signs of the Ebstein abnormality, which usually improve when pulmonary vascular resistance reduces.
  • Adult life: Fatigue, exertional dyspnea, cyanosis, tricuspid regurgitation and/or right heart failure, and palpitations are common symptoms of Ebstein abnormality; arrhythmias are also common.

 

Background

Ebstein's anomaly (EA) is a tricuspid valve (TV) abnormality associated with right ventricle (RV) myopathy with varying anatomic and pathophysiologic features. The lesion is extremely rare, with a 1 in 20,000 chance of developing it.

Anatomical features include:

  1. Failure of TV leaflet delamination, 
  2. Apical descent of the functional tricuspid orifice, 
  3. Right ventricular dilation and “atrialization,” 
  4. Anterior leaflet abnormal fenestrations and tethering, and
  5. Right atrioventricular junction dilation .

 

The degree of apical displacement of the septal leaflet is what distinguishes EA from other congenital regurgitant diseases.

Chordae are also vary, ranging from none to a few, and leaflet fenestrations are prevalent. The right ventricle is dilated in both atrialized (nontrabeculated myocardium between the anatomic and functional TV annulus) and trabeculated parts. Due to higher right-sided pressures and tricuspid regurgitation, patent foramen ovale and/or atrial septal abnormalities are common, with many resulting in right-to-left shunting. These can cause cyanosis and/or paradoxical embolism in patients, especially in adults.

Because of the underlying variability of illness anatomy and physiology, patient presentation varies. Although most individuals are diagnosed in childhood or adolescence, it is possible to be diagnosed as an adult. Adults frequently experience arrhythmias, with atrial fibrillation, flutter, or ectopic atrial tachycardia occurring in up to 40% of newly diagnosed patients.

 

Pathophysiology

The severity of the lesion affects the hemodynamic anomalies. The degree of tricuspid valve displacement and the degree of tricuspid regurgitation are the key determinants. The tricuspid valve function is near to normal in mild Ebstein anomalies. Blood is driven into the atrialized RV with each atrial contraction in mild to severe forms.

Blood is pumped back into the right atrium during ventricular contraction. This is especially true in children who have a lot of tricuspid regurgitation. This causes right atrial dilation and elevated right atrial pressure, which causes a right-to-left shunt across the ASD/PFO. As a result, pulmonary oligemia and arterial desaturation occur.

 

Diagnosis

Electrocardiogram, chest radiograph, 24-hour Holter monitor, echocardiogram, and as-needed cardiopulmonary exercise testing are all routinely performed on EA patients. Cardiac magnetic resonance is an excellent tool for determining the size and function of the RV.

PR interval prolongation, towering P waves, and a degree of right bundle branch block are all common electrocardiographic findings. Atrial tachycardia, such as atrial fibrillation, atrial flutter, or ectopic atrial tachycardia, is present in 25% to 65 percent of patients, while accessory pathways, such as Wolff-Parkinson-White syndrome, are present in 10% to 45 percent of patients. In roughly 10% of patients, atrioventricular nodal reentrant tachycardia is present.

Multiple accessory routes (6 percent to 36 percent) are prevalent and may raise the risk of sudden cardiac death. When a pre-excitation route is present, a preoperative electrophysiologic examination is recommended, and most patients can be treated percutaneously.

A globular look is classic on chest radiograph due to right atrial enlargement, although cardiac profile may appear reasonably normal. The imaging standard in EA is transthoracic echocardiography, which allows for TV leaflet and subvalvular characterisation, right-heart size and function (atrium and ventricle), and dynamic assessment of intracardiac shunts and related cardiac abnormalities.

The flow of color Doppler is essential for determining the severity of tricuspid regurgitation. The presence of septal leaflet tissue and mobility of the anterior leaflet with a free leading edge are both favorable echocardiographic markers for TV repair. Any delamination of the inferior leaflet and septal leaflet helps successful circumferential (cone) reconstructive planning.

Leaflet anchoring to the endocardium with muscularization, on the other hand, indicates a more challenging repair. Severe annular dilatation, which can reach 8 cm or more in adults, is another factor that makes effective repair challenging. RV volumes and tricuspid regurgitation are measured using gadolinium-enhanced cardiac magnetic resonance imaging.  

 

Management

The justification for surgery in newborns and babies with cyanosis and congestive heart failure is unclear, and surgery should be decided on an individual basis. Neonates in need of repair provide a significant difficulty. NYHA class 3 or 4, NYHA class 1 or 2, but a CT ratio of 0.65 or more, substantial cyanosis, paradoxical embolism, and intractable arrhythmia are all reasons for surgery in older children and adults.

The severity and age of the presentation determine the course of treatment. Unless the cyanosis is severe, an asymptomatic cyanotic newborn does not require active treatment. The treatment involves of infusing prostaglandin E1 into the PDA to maintain it open until the PVR lowers. Intubation and positive pressure breathing may aid in the treatment of pulmonary hypertension.

For poor cardiac output, bicarbonate and inotropic infusions will be required to correct metabolic acidosis. Anti-failure drugs can help with the symptoms of tricuspid regurgitation heart failure. Anti-arrhythmia drugs should be used to treat supraventricular tachycardia caused by the auxiliary route or atrial flutter caused by an enlarged atrium. To stabilize a newborn with a restrictive PFO/ASD, a balloon atrial septostomy may be required.

For the therapy of Ebstein abnormality, a variety of surgical techniques have been described. By reducing the considerable left to right shunting and mild cyanosis, surgical closure of ASD may provide symptomatic relief. The Danielson repair involves plication of the atrialized section of the RV, narrowing the tricuspid valve, and generating a competent monoleaflet tricuspid valve.

The Carpentier repair entails plicating the atrialized section of the RV and narrowing the tricuspid valve annulus in the opposite manner from the Danielson procedure. The anterior and posterior leaflets are mobilized from their abnormal attachments, their detachable edges are rotated clockwise, and they are sutured to the septal edge of the anterior leaflet at the level of the tricuspid valve annulus in the Cone technique.

A small percentage of patients receive a one-and-a-half repair. Patch closure of the ASD, repair of the tricuspid valve, and decrease of the RV's atrialized component are all part of the procedure. In the rare cases of tricuspid stenosis and hypoplastic right ventricle, a Fontan procedure may be performed.

 

Tricuspid valve repair

The purpose of operational intervention is to repair the tricuspid valve; correction often comprises RV plication, right atrial reduction, and atrial septal closure or subtotal closure. While tricuspid repair is the preferred option, it should be noted that the outcomes of tricuspid replacement in adult patients show that it is both safe and successful. Arrhythmia surgery is recommended with the assistance of an electrophysiologist who is skilled in EA. Ventricular unloading using a bidirectional cavopulmonary shunt is used sparingly and is usually reserved for patients with poor RV function.

Many approaches and surgical adjustments have resulted in the evolution of tricuspid repair. The anterior leaflet monocuspid valve was the focus of early repair efforts. The original Danielson approach entailed relocating the genuine tricuspid annulus, as well as plication of the atrialized section of the RV free wall and right atrial reduction.

Following Danielson revisions, anterior papillary muscle approximation to the ventricular septum (through the Sebening stitch) was added to enable leaflet coaptation with the ventricular septum. The Carpentier-Chauvaud monocusp repair method emphasized anterior leaflet mobilization with reattachment at the annulus anteriorly, the use of an annuloplasty ring, and atrialized RV plication.

The current approach is the "cone reconstruction" method, which was an expansion of the Carpentier technique in which septal and inferior leaflet tissues were mobilized and then the sides of all the mobilized leaflets were joined in such a way that 360 degrees of leaflet tissue was created. After that, the freshly manufactured "cone" was reattached to the genuine annulus. As a result, the repair is nearly anatomic.

Older age (> 60 years), pulmonary hypertension, biventricular dysfunction (left ventricular ejection fraction 30 percent), lack of septal leaflet tissue and minimal delaminated anterior leaflet tissue (50 percent), and severe enlargement of the RV with corresponding severe dilation of the right atrioventricular junction are all potential contraindications to cone reconstruction.

While there is a large learning curve for a surgeon trained in cone reconstruction, early mortality is fairly low (1%), with high rates of valve repairability (> 98%) in experienced institutions. Tricuspid re-repair is possible, especially if the previous repair concentrated solely on annular motions and left the subvalvar apparatus undisturbed.

When repair is not an option, tricuspid valve replacement with a tissue prosthesis is an option. Older patients with a severely enlarged RV or TV annular dilation, in particular, may benefit from TV replacement over repair due to reduced cross-clamp time (cross clamp can be removed after the patent foramen ovale/atrial septal defect is closed). Bioprosthetic valve performance in the tricuspid position is relatively durable, and chronic anticoagulation may be avoided in most cases.

When a bioprosthetic fails, tricuspid valve-in-valve replacement strategies are becoming more feasible. Due to the risk of disc motion abnormalities and the associated risk of valve thrombosis, mechanical valves are typically avoided in the setting of severe RV dysfunction.

Surgeons outline operational solutions for coronary sinus drainage with regard to the valve suture line. To avoid heart block, the valve suture line is inserted in the right atrium when the coronary sinus is near to conduction tissue.

 

Differential Diagnosis

A cyanotic baby with severe cardiomegaly and pulmonary oligemic is highly indicative of Ebstein abnormality. Critical PS or pulmonary atresia with an intact ventricular septum, as well as functional pulmonary atresia, should be considered as differential diagnoses. Tricuspid atresia, transposition of the great arteries (TGA), and tetralogy of Fallot (TOF) can occasionally be mistaken for Ebstein abnormality.

 

Prognosis

Poor prognostic signs include the following:

  • Male sex
  • Earlier age at presentation
  • Cardiothoracic ratio of more than 0.65 on chest radiographs
  • Septal leaflet attachment ratio (ie, ratio of distance between AV ring and distal attachment of septal leaflet to length of septal leaflet) of more than 0.45
  • Increasing the ratio of the total area of the right atrium and atrialized right ventricle to the functional right ventricle from grade 1 (less than 0.5) to grade 4 (more than 1.5). (increase in the relative risk of 2.7 for each increment in the grade)
  • New York Heart Association (NYHA) class: This has been linked with mortality rate in some studies 

 

The disease's natural course varies depending on the degree of tricuspid valve displacement. Patients who appear in infancy typically have severe illness and a poor prognosis.

The average age of presentation is in the midst of adolescence. According to previous observational data, roughly 5% of these individuals survive past the age of 50. The oldest reported patient was 85 years old.

 

Complications

Complications of Ebstein anomaly include the following:

  • Congestive heart failure
  • Sudden cardiac death
  • Bacterial endocarditis
  • Brain abscess
  • Paradoxical embolism
  • Transient ischemic attacks
  • Stroke

 

Ongoing Care

What will I need in the future?

People with Ebstein's abnormality should be followed up on by a cardiologist who specializes in congenital heart problems. If you are undergoing any form of non-heart surgery or invasive treatment, you should also visit a cardiologist who specializes in adult congenital heart disease.

Medical

Aside from standard checks, the cardiologist may employ tests such as electrocardiograms, Holter monitors, and echocardiograms to gather information.

Activity Restrictions

Staying physically active is beneficial to your cardiovascular system, so keep moving. If the valve leakage is minor and no abnormal cardiac rhythms are detected, you should be able to engage in most sports. Your cardiologist may advise you to avoid participating in high-intensity competitive sports. Consult your cardiologist to determine which activities are appropriate for you.

Endocarditis Prevention

If you are cyanotic (blue) or have a prosthetic valve, you may require antibiotics before some dental or surgical operations to avoid endocarditis.

Pregnancy

The heart is put under a lot of strain during pregnancy. Most women with moderate Ebstein's abnormality will be able to deliver a baby safely. Nonetheless, each woman should be assessed on an individual basis. Consult your cardiologist regarding pregnancy safety.

Will you need more surgery?

Mild tricuspid valve leaking patients are unlikely to require surgery at any stage. Patients with moderate to severe leakage may require initial or follow-up surgery. Patients who have had pacemakers implanted require close monitoring and may eventually require pacemaker replacement.

 

Future Directions

To present, therapeutic therapies have mostly concentrated on the enhancement and durability of surgical valve repair procedures and arrhythmia surgery, as well as the timing of operational intervention. Although TV competency has improved and positive RV remodeling has been proposed, the RV myopathy inherent in the disease process persists and may play a role in late symptoms and arrhythmias, as well as late sudden cardiac death.

Cell-based regenerative treatments are being investigated in congenital cardiac disease, particularly EA. At 6-month follow-up, preliminary data showed safety and rebound in RV function; however, comprehensive study follow-up and comparison between study treatment and control groups are not yet available.

 

Conclusion 

Ebstein's abnormality is a congenital cardiac condition in which the tricuspid valve's septal and posterior leaflets are shifted towards the apex of the right ventricle. It is classed as a serious congenital heart condition, accounting for 1% of all congenital heart abnormalities and occurring in 1 out of every 200,000 live births. Ebstein anomaly is the most frequent congenital cardiac defect linked with supraventricular tachycardia.

The majority of newborns with Ebstein abnormality are discovered shortly after delivery. Because these babies require NICU care, the ICU nurse must be conversant with the management of congenital cardiac abnormalities. While some newborns have a single cardiac defect, others may have involvement of many organ systems, necessitating proper consultations.

Surgery is frequently necessary in symptomatic infants after the diagnosis is determined. Following surgery, the newborns must be closely monitored in the NICU for a lengthy period of time until all pacing wires and chest tubes are withdrawn and the child is breathing without the assistance of a mechanical ventilator.

The results are determined by the severity of the abnormality. An early age of presentation, an increased cardiothoracic ratio, an advanced NYHA class, and a high-grade Celermajer index are all poor prognostic markers. Based on case reports and short series, a few patients may now live into their fifth decade.