Ebstein's Anomaly

Introduction

  • Ebstein’s anomaly is a rare congenital condition found in approximately 1 in 20,000 live births
  • Accounts for less than 1% of all congenital heart defects.
  • In mothers who take lithium throughout early pregnancy, the incidence is increased 20-fold; 1 in 1000 live births.

Pathophysiology

Ebstein’s anomaly is a malformation of the tricuspid valve and right ventricle:

  • Tricuspid Valve: incompetent with downward displacement into the right ventricle
    • The septal and posterior leaflets are either absent, or adherent to right ventricular endocardium
      • This is due to a failure of delamination during embryologic development
    • The anterior leaflet is attached to the tricuspid annulus and is long, sometimes described as “sail-like”
  • Right Ventricle: dilated and atrialized
    • Because of the downward displacement of the tricuspid valve, the proximal portion of the right ventricle is described as “atrialized”
    • The distal, non-atrialized, portion of the right ventricle (RV), named the RV proper, is significantly smaller than the proximal portion of the RV.

With the dilated and atrialized RV and an incompetent tricuspid valve, the functional impairment of the right heart results from tricuspid regurgitation and decreased forward flow from the right heart.

ebsteins_0.pnghttp://www.childrenshospital.org/~/media/healthtopics-kidsmd/conditions/...

 

ebsteinspath_0.pngSevere Ebstein’s malformation of tricuspid valve (4-chamber view) showing marked downward displacement of shelf-like posterior leaflet with attachment to underlying free wall by numerous muscular stumps (arrows), markedly dilated atrialized portion of right ventricle (ARV), small functional portion of right ventricle (RV), leftward bowing of ventricular septum, and marked dilatation of right atrium (RA). LA indicates left atrium; LV, left ventricle. http://circ.ahajournals.org/content/115/2/277.full#sec-5

Associated Cardiac Abnormalities

Interatrial communication, such as patent foramen ovale (PFO) and atrial septal defects (ASD), are some of the most common associated abnormalities in patients with Ebstein’s anomaly, found in 80-94% of patients

  • Ebstein's anomaly is the congenital lesion most strongly associated with Wolff-Parkinson-White (WPW) syndrome
  • Up to 20% of patients with Ebstein’s anomaly have one or more accessory pathways.
  • WPW syndrome is an arrhythmic syndrome of intermittent tachycardia resulting from an accessory pathway that bypasses the AV node, directly connecting the atria and ventricle.
    • The classic WPW ECG pattern consists of :
      •  A short PR interval (rapid AV conduction through the accessory pathway)
      • Delta wave (initial slow ventricular activation due to fiber to fiber conduction)
      • A wide QRS complex (fusion of early ventricular activation from the accessory pathway, and later activation from the AV node)

  ebsteinsecg_0.pnghttp://pedsinreview.aappublications.org/content/31/9/375

  • Various other abnormalities, including ventricular septal defect (VSD), patent ductus arteriosus (PDA), coarctation of the aorta, pulmonary outflow tract obstruction, and more have also been found to be associated with Ebstein’s anamoly.   

 

Clinical Presentation

  • The presentation of Ebstein’s anomaly can vary widely, from a cyanotic neonate to a completely asymptomatic patient,
    • This is due to the different severities of tricuspid and right heart anomalies patients may have.
  • Different age groups, however, present more frequently with certain symptoms:

Neonates most often present with cyanosis.

  • Such early presentation is more frequently associated with another cardiac lesion, such as an ASD, allowing for right-to-left shunting.
  • Cyanosis typically improves as pulmonary resistance decreases after birth.

Infants most often present with heart failure

Children most often present with an incidental murmur finding

Adolescents and adults most often present with an arrhythmia, some due to WPW

Physical exam

  • In patients with more severe pathology: cyanosis, distended jugular veins, and hepatomegaly may be found
    • Severe tricuspid regurgitation leads to elevated right atrial pressure, backing up the venous circulation upstream.
  • On auscultation, a systolic murmur, best heard at the left lower sternal border, from tricuspid regurgitation is commonly found.
  • This murmur increases with inspiration, and may be associated with a mild diastolic murmur
    • Due to increased volume traveling through tricuspid valve during diastole

Echocardiogram

  • Echocardiogram is the most useful diagnostic tool for Ebstein’s anomaly.
    • The echocardiogram is able to determine:
      • degree of tricuspid valve displacement and regurgitation
      • right heart dilation
      • other cardiac abnormalities (e.g. atrial septal defect (ASD) or patent foramen ovale (PFO) and their associated shunting)

Electrocardiogram

  • Some ECG abnormalities include
    • Tall peaked P waves: right atrial hypertrophy
    • Right bundle branch block pattern
    • Pre-excitation due to right-sided accessory pathways – characteristic WPW ECG findings may also be seen, as discussed above
    • Low-voltage QRS in the right-sided chest leads

 

ecgebsteins2_0.png   ECG from a patient with Ebstein's anomaly showing huge P waves and low amplitude QRS waves. RBBB and T wave inversion are not present on this ECG. http://en.ecgpedia.org/images/c/c2/E000403.jpg

 

Chest Radiograph

  • In patients with severe disease, marked cardiomegaly with decreased pulmonary vasculature markings may be seen. 
  • Shown below is the chest x-ray of a patient with Ebstein's anomaly which demonstrates cardiomegaly:

xrayebsteins_0.pnghttp://www.wikidoc.org/index.php/File:Ebstein%27s_anomaly_001.jpg

 

Management

  • Patients are treated depending on their presentation – asymptomatic patients may need no treatment, but should continue to be closely monitored.
  • Cyanotic newborns are given supportive therapy until pulmonary vascular resistance drops
    • Nitric oxide may also help improve pulmonary blood.
  • Endocarditis prophylaxis is recommended for cyanotic patients with Ebstein’s anomaly.
  • Infants with heart failure may be treated with digoxin and diuretics.
  • Patients with a history of paradoxical emboli (via an ASD or PFO) or atrial fibrillation, anticoagulation is recommended.
  • Patients with arrhythmias due to accessory pathways may have radiofrequency or surgical ablation
  • Surgical tricuspid valve repair or replacement is recommended for patients with progressive symptoms, right heart failure, cardiomegaly, severe cyanosis, or paradoxical embolism.

 

References

  1. Biondi, E. A. "Focus on Diagnosis: Cardiac Arrhythmias in Children." Pediatrics in Review 31.9 (2010): 375-79. Web
  2. Congenital Heart Disease for the Adult Cardiologist: Ebstein’s Anomaly
  3. Christine H. Attenhofer Jost, Heidi M. Connolly, Joseph A. Dearani, William D. Edwards, and Gordon K. Danielson Circulation. 2007;115:277-285, doi:10.1161/CIRCULATIONAHA.106.619338
  4. "Ebstein's Anomaly for Adults | Cleveland Clinic." Ebstein's Anomaly for Adults | Cleveland Clinic. Cleveland Clinic, n.d. Web.
  5. "Ebstein's Anomaly of the Tricuspid Valve." Ebstein's Anomaly of the Tricuspid Valve. UptoDate, n.d. Web.
  6. Left heart lesions in patients with Ebstein anomaly. AU Attenhofer Jost CH, Connolly HM, O'Leary PW, Warnes CA, Tajik AJ, Seward JBSO Mayo Clin Proc. 2005;80(3):361.

 

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