Ebstein Anomaly

Grade the lesion before you start - Echocardiography is the study of choice: apical displacement of the septal leaflet greater than 8 mm/m2 in the apical 4-chamber view, RV size and function, septal flattening, and the severity of tricuspid regurgitation. TEE beats transthoracic imaging for seeing the leaflets and for detecting the intracardiac shunt. Cardiac MRI quantifies RV ejection fraction better than echo does. The tricuspid lesion itself is covered in the separate Tricuspid Regurgitation entry.

Assume the shunt is there - More than 80% have a secundum ASD or a stretched patent foramen. Severe tricuspid regurgitation drives right-to-left flow across it, so a fall in systemic vascular resistance or a rise in pulmonary vascular resistance deepens the cyanosis in front of you.

Debubble everything - Paradoxical emboli across the atrial communication have caused stroke, brain abscess and myocardial infarction in these patients. Purge every line, use air filters, and be meticulous with injections and infusions.

Accessory pathways are the norm - Get a 12-lead and look for pre-excitation. Accessory pathways are present in 10% to 45%, frequently multiple, and 5% to 25% have Wolff-Parkinson-White (WPW) — Ebstein is the congenital lesion most often paired with WPW. The septal leaflet can also compress the AV node and disrupt conduction.

Atrial arrhythmias are common and poorly tolerated - Atrial fibrillation, flutter or ectopic atrial tachycardia occurs in 25% to 65%. Cardiovascular collapse and arrhythmia are what sudden death in Ebstein is usually attributed to, and the 50-year cumulative incidence of sudden cardiac death from ventricular arrhythmias is 8.6%. Pads on before induction, and have a plan.

Rate and rhythm drugs - Beta blockers or calcium channel blockers for rate control, with class I or III agents (procainamide, sotalol, amiodarone) when those fail. In a prospective obstetric series, an IV amiodarone infusion resolved postpartum atrial arrhythmia within 12 hours.

Catecholamine choice matters - Milrinone is the inotrope of choice in the failing right heart here because it also vasodilates the pulmonary bed. Epinephrine and norepinephrine are usually avoided — they carry a high risk of tachyarrhythmia in these patients.

Keep pulmonary vascular resistance down - Inhaled nitric oxide reduces PVR and hypoxemia in symptomatic infants. In the cyanotic neonate, prostaglandin E1 keeps the ductus open and adds pulmonary vasodilation.

Neuraxial labor analgesia is reasonable - In a prospective series of seven women with unrepaired Ebstein in NYHA class II, epidural analgesia was safe and facilitated spontaneous or instrumental vaginal delivery without hemodynamic or respiratory compromise. Close hemodynamic surveillance through delivery and the early postpartum period is what made the difference.

Watch the left ventricle too - RV volume overload flattens the septum and impairs LV function. In one case from that series, preeclampsia precipitated left ventricular failure with pulmonary edema and desaturation during the second stage, treated with labetalol and furosemide.

Ask about anticoagulation - Oral anticoagulation is used in Ebstein patients with atrial fibrillation or documented paradoxical embolus. Find out the agent and the last dose, then take neuraxial timing from the current ASRA anticoagulation guidelines and the cardiology plan — not from memory and not from this entry.

Endocarditis prophylaxis - Recommended before dental procedures in patients with Ebstein and cyanosis, and after surgical repair involving a prosthetic valve.

Know which repair they had - Cone reconstruction (da Silva) is the current preferred approach in children and adults; the Danielson and Carpentier repairs plicate the atrialized RV. A surgical bi-atrial Maze is often done at the same sitting, because catheter ablation carries paradoxical embolus risk given the interatrial shunt and has a higher recurrence rate here than in structurally normal hearts.

Ebstein anomaly is a failure of the tricuspid leaflets to delaminate from the interventricular septum in utero. The septal and posterior leaflets end up displaced apically — by definition more than 8 mm/m2 below the true annulus — which splits the right ventricle (RV) into an "atrialized" portion that is fibrotic and dyskinetic and a small "functional" RV that in severe cases is little more than the outflow tract.

The valve cannot coapt, so tricuspid regurgitation is the rule, and the right atrium and atrialized RV dilate around it. RV volume overload flattens the interventricular septum and drags down left ventricular function. More than 80% of these patients also carry a secundum atrial septal defect or a stretched patent foramen, so severe regurgitation pushes blood right to left across it — producing hypoxemia, cyanosis, and a standing route for paradoxical emboli. Ebstein accounts for 0.3% to 0.6% of congenital heart disease.