TETRALOGY OF FALLOT
WITH ABSENT PULMONARY VALVE
This is an uncommon variation of tetralogy of
Fallot. The pulmonary valve leaflets are represented by nubbins of tissue.
The clinical picture is dominated by pulmonary insufficiency rather than
The anatomy is the same as tetralogy of
Fallot except that the right ventricular outflow tract is not excessively
restrictive. The pulmonary arteries are dilated and sometimes aneurysmal.
The pulmonary artery dilatation may extend beyond what is expected from
pulmonary insufficiency to several generations of pulmonary arteries
causing bronchial constrictions.
A systolic and diastolic murmur is present.
This represents pulmonary stenosis and pulmonary insufficiency.
The chest x-ray shows aneurysmal dilatation
of the main pulmonary artery.
The cardiac catheterization is important to
delineate the peripheral pulmonary arteries.
Management is delayed as much as possible
because of the need to place a valve, usually a homograft. Surgery is done
earlier in patients with dilated distal pulmonary arteries and respiratory
distress to halt further progress of bronchoconstriction. Pulmonary
arteries could be plicated during surgery. Hypercyanotic spells are not a
feature of this type of tetralogy of Fallot.
TETRALOGY OF FALLOT
WITH AV CANAL DEFECT
In tetralogy of Fallot with AV canal
presentation is similar to that of typical tetralogy of Fallot. The
electrocardiogram shows superior axis deviation with right ventricular
hypertrophy. In almost all instances the anterior atrioventricular valve
leaflet is free floating. Due to the complexity of this congenital heart
disease, cardiac catheterization is almost always performed. Surgery is
usually done at 1 year of age where the AV canal and tetralogy of Fallot
are repaired simultaneously. There is a higher instance of Down syndrome
in comparison to other types of tetralogy of Fallot.
TETRALOGY OF FALLOT
WITH DOUBLE CHAMBER RIGHT VENTRICLE
This typically occurs due to hypertrophy of
the moderator muscle bundle. In these instances the right ventricular apex
pressure is higher than the rest of the right ventricle. During surgical
repair the moderator muscle bundle should be severed so as to eliminate
the pressure gradient
Fallot with pulmonary atresia
Eighteen per cent (18%) of patients with
tetralogy of Fallot have pulmonary atresia. Pulmonary atresia can be
congenital or acquired. The VSD is of the malalignment type and there
might be other types of VSD seen. Like tetralogy of Fallot with pulmonary
stenosis 25% of these patients have a right aortic arch. Although in some
estimates that is thought to be as frequent as 50%.
These patients have collaterals, 70% of the
them have patent ductus arteriosus feeding into the pulmonary arteries and
30% of such patients have collateral vessels. Collateral vessels could
come from the descending aorta or the brachiocephalic arteries. Collateral
vessels may feed one side of the lungs, both sides or cross to the
opposite side. Collaterals are typically from the thoracic aorta and less
common from the subclavian artery and rarely from the descending aorta
directly or left carotid artery. Embryologically, the lungs are supplied
by primitive blood vessels from the descending aorta and in patients with
pulmonary atresia these vessels may persist as collaterals. Bronchial
arteries may supply the blood to the lungs. Pulmonary arterial pressure
tends to be normal or below normal because of narrowing of collateral and
pulmonary hypertension is not frequently encountered in these kind of
cases. Symptom cyanosis is not very clear since there is an increase in
pulmonary blood flow to multiple collaterals and the patient presents with
congestive heart failure more than cyanosis.
Cardiac catheterization is necessary in all
such patients except those that are severely cyanotic and require an
urgent systemic to pulmonary arterial shunt placement. In the cardiac
catheterization the pulmonary arteries should be studied as well as the
collateral circulation and coronary artery anatomy as well as other
VSDís that might be associated with a malalignment VSD. Patients with
increased pulmonary blood flow and congestive heart failure could benefit
from coil occlusion of collateral vessels. Pulmonary arteries grow best if
they have increased pulmonary blood flow and particularly if it is from
the right ventricle. Therefore, increasing pulmonary blood flow through
the pulmonary arteries is important to do as soon as possible to allow the
pulmonary arteries to grow and enable complete repair. If collateral blood
vessels provide the lung segments with blood not provided through the
pulmonary artery then incorporation of that collateral through a process
of vena focalization should be considered. Three-quarters (3/4) of the
total lung capacity should be incorporated in the repair, i.e., 15 of the
20 segments or 1-1/2 lung should be incorporated in the unifocalization
repair. Systemic to pulmonary arterial collaterals should be either
included in the unifocalization process or occluded by cause in the cath