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EBSTEIN'S ANOMALY

Description

A rare congenital cardiac abnormality that has the following characteristics:

  1. Malformed tricuspid valve leaflets displaced downwards with adherence of the septal and posterior leaflets to the myocardium. The valve is usually regurgitant but may be stenotic (this is rare). The anterior leaflet may be redundant and may be fenestrated.

  2. Downward displacement of the tricuspid valve annulus.

  3. The part of the right ventricle (RV) adjacent to the valve is atrialised, thus reducing RV function.

  4. In 50% of cases, there is a patent foramen ovale (PFO) or atrial septal defect (ASD) through which right-to-left shunting may occur, causing cyanosis.

Pathophysiology

  1. The RV contracts poorly and may dilate, contributing to tricuspid valve incompetence.

  2. PFO or ASD may result in right-to-left shunt and increased risk of paradoxical embolus. This is even more likely if pulmonary stenosis is present. See Pulmonary stenosis (PS).

  3. Varying degrees of tricuspid regurgitation.

  4. Right atrial (RA) dilatation may cause arrhythmias.

  5. As the demarcation of the RA and RV is disrupted, WPW occurs in about 20% of cases.1 See Wolff–Parkinson–White (WPW) syndrome.

  6. There may be left heart involvement with impaired left ventricular (LV) systolic/diastolic dysfunction. This may be due to the dilated RV displacing the ventricular septum and compressing the LV and impairing filling.

  7. CO tends to be ‘fixed’.

  8. There may be pooling and recirculation of blood in the right atrium.

  9. Pulmonary hypertension may be present.

Clinical features

The patient's condition may range from asymptomatic to critically ill.

  1. Fatigue.

  2. Heart murmur—pansystolic.

  3. Cyanosis.

  4. Paradoxical embolus.

  5. Heart failure.

  6. Arrhythmia.

Diagnosis

  1. Echocardiography.

  2. Cardiac MRI.

  3. ECG—tall, wide P waves, first degree AV block.

Anaesthesia

This condition is rare and varies in severity. Advice is difficult to give as there are relatively few case reports. Patients require review by a cardiologist and appropriate preoperative investigation. Surgery under LA or regional block is preferred. Involvement of a cardiac anaesthetist is advisable. Also, consider the following.

  1. Antibiotic prophylaxis for relevant defects/surgery. See Bacterial endocarditis (BE) prophylaxis.

  2. Etomidate may be considered for anaesthetic induction due to its negligible effects on heart function. See Etomidate. Etomidate is not currently available in Australia.

  3. Aim for haemodynamic stability, avoiding hypotension and hypertension, and bradycardia and tachycardia. Hypovolaemia and new-onset arrhythmia may be poorly tolerated. Maintain preload and afterload.

  4. Avoid any measures that would increase pulmonary vascular resistance in patients with right-to-left shunt (N2O, hypoxia, hypercarbia, acidosis, high intrathoracic pressures).

  5. Avoid introducing any IV air, which may result in paradoxical embolus.

  6. Consider invasive monitoring (arterial line, CVP).

  7. Postoperative DVT prophylaxis is extremely important.

Obstetrics

Women with Ebstein's anomaly who are not cyanosed and not in heart failure may tolerate pregnancy well. ...

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