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Rao. Vessel Plus 2022;6:26 https://dx.doi.org/10.20517/2574-1209.2021.93 Page 35 of 43

Although patients with no other heart defects have been reported, the majority of CCTGA cases have other
significant heart defects, namely, VSD, right-sided MLV outflow tract narrowing, atrio-ventricular block
(spontaneous or after catheter or surgical intervention) and an Ebstein’s type of abnormality of the
[55]
morphologic tricuspid valve on the left-side . The right-sided MLV outflow tract narrowing is seen in 44%
to 57% of cases . More common causes of such obstruction are pulmonary valve atresia, valvar PS, and
[52]
sub-pulmonary stenosis secondary to muscular mal-alignment and/or hypertrophy. Less frequently seen
reasons are accessory valve tissue, fibrous tags, membranous septal aneurysms, and intra-cardiac blood
[52]
cysts .
The amount of downward dislocation of the left-sided tricuspid valve is assessed in a four-chamber view
[Figure 64]. The size, location and shunting across the VSD should be demonstrated. The degree of PS may
be quantified by Doppler studies using the modified Bernoulli equation.

Echocardiographic examples of ventricular septal aneurysms causing obstruction to MLV both in cases with
[56]
[52]
levocardia [Figure 65] and dextrocardia [Figures 66 and 67] are shown.
EBSTEIN’S ANOMALY OF THE TRICUSPID VALVE
Ebstein’s malformation of the tricuspid valve is a CHD comprising downward (towards the apex of the
heart) displacement of septal and posterior leaflets of the tricuspid valve [4,51,57-60] . In addition, there are
redundant tricuspid valve leaflets and tricuspid valve apparatus dysplasia, producing regurgitation and
infrequent stenosis. Varying degrees of downward dislocation of the tricuspid valve attachment from a few
mm to all the way close to the parietal band and crista supraventricularis have been reported. The RV inflow
portion from the true to false annuli of the tricuspid valve is named atrialized RV and forms a common
compartment with the RA. Severe RA dilatation is also present. Pulmonary atresia or stenosis may be seen
in some cases. Ebstein’s malformation of the tricuspid valve is an uncommon congenital cardiac defect
comprising 0.3% to 0.6% of all CHDs.

The pathophysiology is variable and is largely related to the extent of downward dislocation of the tricuspid
valve leaflets. In subjects with moderate to severe degrees of Ebstinization of the tricuspid valve, RA
contraction propels the blood into the atrialized component of the RV, and with each RV contraction, the
RV blood is ejected back into the RA; such “ping-pong” effect increases RA pressure, produces RA
[51]
enlargement resulting in a shunt from RA to LA across the PFO/ASD. In the neonate with high pulmonary
vascular resistance (PVR), this effect becomes more pronounced, causing severe cardiomegaly and
decreased pulmonary blood flow. As the PVR falls, the infant will have reduced cyanosis. However, this
abnormality returns late during childhood and adolescence because of decreased efficiency of the tricuspid
valve apparatus. The role of high PVR in the neonate should be recognized while performing and
interpreting the echo study by the echocardiographer.

A two-dimensional echocardiogram shows RA enlargement and downward dislodgment of the tricuspid
valve leaflets [Figures 68A and 69A]. The anatomy of the leaflets, including valve dysplasia and
abnormalities of the chordal attachments, should be evaluated. Doppler studies show tricuspid insufficiency
[Figure 68B] and shunting from RA to LA via the PFO [Figure 69B]. Peak tricuspid regurgitation velocity
may be used in estimating the RV/PA systolic pressures by the use of a simplified Bernoulli formula. The
patency of the ductus should also be evaluated. Even though the atrialized part of the RV bulges into the LV
outflow tract [Figure 70], clinically significant LV outflow tract obstruction rarely occurs.