Congenital Heart Disease part 6

EBSTEIN'S ANOMALY

Ebstein's anomaly is a relative rare disease and characterized by abnormally formed and apically displaced  leaflets of the tricuspid valve. Tricuspid valve opening is dislocated away from from the tricuspid valve annulus towards the apex or the right ventricular outflow tract. The anterior leaflet usually originates appropriately at the annular level but enlarged and sail-like, while the septal and posterior leaflet are displaced towards the right ventricular apex and often tethered to the endocardium.

The apical displacement of the tricuspid valve means that the right heart consists of an right atrium, an atrialized portion of the right ventricle, and the remaining functional right ventricle. The tricuspid valve is often regurgitant.

The most frequently associated anomalies include a shunt at the atrial level (secundum atrial septal defect or patent foramen ovale) and accessory pathways (Wolf-Parkinson-White syndrome). Ventricle septal defect, pulmonary stenosis, pulmonary atresia, tetralogy of Fallot, coarctation of the aorta, or mitral valve abnormalities can also occur .

Ebstein's anomaly occurs more commonly if the mother has received lithium or benzodiazepins during pregnancy.

The morphological and haemodynamic spectrum is wide. Haemodynamic changes depend on the severity of the tricuspid valve dysfunction, the degree of atrialization of the right ventricle, contractility of the remaining functional and the systemic ventricle, type and severity of concomitant anomalies and arrythmias.

The pathophysiology is characterized by systolic regurgitation of blood from the functional right ventricle, across the tricuspid valve, into the atrialized ventricle or right atrium, which tend to dilate. An interatrial connection permits an left-right shunt, or especially during exercise, an right-left shunt. Eibstein anomaly may result in chronically low systemic cardiac output.

The clinical presentation ranges from trivial symptoms to the presentation of profound cyanotic heart
defect. Patients with mild forms can be asymptomatic over decades until they are diagnosed. Key symptoms are arrhytmias, dyspnoea, fatigue, poor exercise tolerance, chest pain and peripheral and/or central cyanosis.


TETRALOGY OF FALLOT

Tetralogy of fallot is the most common form of cyanotic congenital heart diesease after 1 year of age, with an incidence approaching 10% of all forms of congenital heart defect. The defect is due to antero-cephalad deviation of the outlet septum resulting in the following four features:  a non-restrictive ventricle septal defect, overriding aorta (but<50%), right ventricular outflow  tract obstruction which may be infundibular, valvular, or (usually) a combination of both, with or without supravalvular or branch pulmonary artery stenosis, and consequent right ventricle hypertrophy.

Associated lesions include atrial septal defect, additional muscular ventricle septal defect, right aortic arch, anomalous (can be dual) left anterior descending coronary artery which may necessitate a conduit type of repair, and complete atrioventricular septal defect (rare, usually in association with down syndrome)

Early clinical presentation is dominated by a heart murmur in infancy and progressive cyanosis (from right to left  shunting at the ventricular level secondary to right ventricular outflow tract obstruction). Unoperated tetralogy of fallot carries a poor prognosis (>95% of patients used to die before 40 years of age). Early management may include paliative procedures to increase pulmonary blood flow.