transposition of the great arteries (tga) vsd ps

transposition of the great arteries (tga), vsd, ps

the four chamber view is typically normal. the great arteries arise in parallel orientation with the aorta arising from the right ventricle anterior and to the right of the pulmonary artery, which arises from the left ventricle. there is a ventricular septal defect. there is subpulmonary and pulmonary valvular stenosis. the pulmonary artery is smaller than the aorta.

transposition of the great arteries (tga)-simple

the four chamber view shows slight right ventricular dominance. the great arteries are seen arising in parallel orientation. the aorta, which gives rise to the arch, is connected to the right ventricle and the branching pulmonary artery is connected to the left ventricle. the aorta is anterior to the pulmonary artery (the reverse of normal).

ebstein's, corrected tga

the posterior av valve is displaced into the ventricular cavity. this ebstein’s malformation affects the tricuspid valve. this indicates that the posterior ventricle is the morphological r ventricle. thus the r atrium is connected to the l ventricle, the l atrium to the r ventricle. the great arteries arise side by side with the aorta to the left of the pulmonary artery.

description

the great arteries are reversed in their connection to the ventricles, but in addition there is a ventricular septal defect and the pulmonary valve is stenosed or partially obstructed. the infant will present with cyanosis. enlarging the atrial communication by balloon atrial septostomy may be necessary to ensure mixing. if pulmonary stenosis is severe, shunt placement may be necessary. this type of patient will eventually have a rastelli repair, where the aorta is connected to the left ventricle, the vsd closed and a conduit placed between the right ventricle and the pulmonary artery. this is usually delayed for a few years to avoid several conduit replacements with growth.

diagnosis

the great arteries will arise in parallel orientation, with the aorta from the right and the pulmonary artery from the left ventricles respectively. the aortic valve is usually anterior and to the right of the pulmonary artery. the pulmonary valve will be thickened and doming and the pulmonary artery will be smaller in size than the aorta. there will be turbulent accelerated flow across the pulmonary valve. the associated ventricular septal defect can be of variable size and in any site in the septum although perimembranous is the most common site.

differential diagnosis

this echocardiographic picture may be mistaken for double outlet right ventricle with pulmonary stenosis but the difference is not of much practical importance. care must be taken to ensure that the ventricles are not inverted as parallel great arteries, with disproportion of the arterial sizes, can be a presentation of corrected transposition with pulmonary stenosis. in complete transposition, the posterior, left-sided ventricle should be less trabeculated at the apex than the anterior right ventricle, which contains the moderator band. in addition, the tricuspid valve in the anterior right ventricle is situated more apically than the mitral valve in the posterior left ventricle (the normal off-setting of the av valves).

sonographic features

parallel origin of the great arteries, aorta from right, pulmonary artery from left ventricles (no ‘cross-over’).

thickened, doming pulmonary valve.

pulmonary artery smaller than aorta.

vsd.

associated syndromes

asplenia (ivemark)
digeorge syndrome
hypertelorism
hypospadias
tof
maternal diabetes
maternal epilepsy- untreated
noonan’s
retinoic acid embryopathy (accutane embryopathy)
short rib-polydactyly syndrome non-majewski type
trimethadione

references

anderson rh, mccartney fj, shinebourne ea, tynan m (eds) in: paediatric cardiology churchill livingstone: edinburgh, p829-867
allan ld, sharland gk, milburn a, lockhart sm, groves amm, anderson rh, cook ac, fagg nlk prospective diagnosis of 1,006 consecutive cases of congenital heart disease in the fetus j am coll cardiol 23:1452-8
allan ld, sharland g, cook a in: colour atlas of fetal cardiology mosby-wolfe: london, p109-115
paul mh in: heart disease in infants, children and adolescents adams fh, emmanouilides gc, riemenschneider ta (eds) williams and wilkins: baltimore, p371-424
kirklin jw, colvin ev, mcconnell me, bargeron lm jr complete transposition of the great arteries: treatment in the current era pediatric clinics of north america 37:171-7