The document discusses Truncus Arteriosus, which is a rare congenital heart defect where there is only a single arterial trunk arising from the heart to supply the pulmonary and systemic circulations. It can be classified into four types based on the anatomy and flow. Type I and II make up 85% of cases. Complications include valve incompetence, coronary artery abnormalities, and association with other conditions like DiGeorge syndrome. CT imaging is useful for assessing the anatomy and complications. The role of each structure is described in detail. Other similar great vessel defects like Aortopulmonary Window and Hemitruncus Arteriosus are also summarized briefly.

1. Truncus Arteriosus
By
Dr.M.Gibreel, FEBR, FAHC
Cardiac imaging senior Registrar
AHC & NHI

2.  Only a single arterial trunk with a truncal valve leaflets the heart and gives
rise to the pulmonary, systemic, and coronary circulations. A large
perimembranous or subarterial (subtruncal) VSD is present directly below
the truncus .
 The truncal valve may be bicuspid, tricuspid, or quadricuspid, and it is
often incompetent.

3. Types (Collett and Edwards’ classification)

4.  Types I and II constitute 85% of cases.
 Type IV is not a true persistent truncus arteriosus; rather, it is a severe form
of TOF with pulmonary atresia (i.e., pseudo-truncus arteriosus), with aortic
collaterals supplying the lungs.
 The pulmonary blood flow is increased in type I, nearly normal in types II
and III, and decreased in type IV.
 Coronary artery abnormalities are common >> high surgical mortality rate.
The anomalies include stenotic coronary ostia, high and low takeoff of
coronary arteries, and abnormal branching and course of the coronary
arteries.

5.  A right aortic arch is present in 30% of patients.
 DiGeorge syndrome with hypocalcemia is present in 33% of patients.
Role of CT
 Confirm the diagnosis , Anatomy & type (with delineation of MPA ,PAs
 Number of sinuses & coronary origins (exclude ostial stenosis) , course &
abnormalities.
 We reported a Truncus type I with the coronary arteries supplied by a collateral
arises from the right common carotid artery no any communication between
the seen single coronary artery and the truncus root ,,, SEE OUR AHC CASE
FILE,,,,,,

6. TA type I

12.  Heart:
 Situs solitus, levocardia.
 Atrio-ventricular concordance.
 Dilated LV&LA. Mild RVH.
 A cono-truncal VSD is seen with an overriding single
trunk; truncus arteriosus.no other VSDs.
 Intact IAS.
 No pericardial effusion, cardiac masses or thrombi.

13.  Great vessels of the chest:
 Single trunk (truncus arteriosus type I) is seen overriding the VSD, showing wide
root, supplying the thoracic aorta & MPA.
 Trileaflets truncal valve with thickened leaflets & ?? bicuspid opening for echo
correlation. Truncal annulus measures 44x31mm.
 Dilated truncal root as it measures 65x50 mm at sinus level.
 The ascending aorta is also aneurysmally dilated showing homogenous contrast
opacification, appears as the continuation of the truncus and measures about 52x51
mm in diameter.
 The aortic arch is left-sided showing mild dilatation as its mid segment (between LT
CCA & LT SCA) measures (31x31mm). It supplies the right branchio-cephalic trunk,
the left CCA , the left vertebral and the left subclavian artery, respectively.
 No evidence of aortic coarctition. No PDA.
 Average caliber of the descending aorta (16x15 mm in average diameters) at the level
of the diaphragm.
Few minor aorto-pulmonary collators to both hila

14.  The coronary arteries:
o The LCA arises from the right postero-lateral aspect of the truncus , and divides to supply
the LAD and LCX arteries. The LCA ,LAD & LCX show normal course, caliber & termination.
o The Dominant RCA arises from the right antero-lateral aspect of the truncus . The RCA
shows normal course, caliber and termination.
 The main pulmonary artery (MPA) arises from the left lateral aspect of the
truncus, it measures about 40x31 mm in average diameters, It divides supplying
the right and left pulmonary arteries.
 The RPA measures 25x22 & 25x25 mm in its proximal & pre-branching diameters
respectively, it shows homogenous opacification and normal branching pattern.
 The LPA measures 20x18 & 24x22 mm in its proximal & pre-branching diameters
respectively, it shows homogenous opacification and normal branching pattern.
 The pulmonary veins are homogenously opacified, they drain normally into the
left atrium. No evident APVD.

15.  Systemic veins:
 Normal course and caliber of the LT BCV, right SVC and IVC which drain normally to
RA.

 Lung parenchyma:
 Relatively plethoric both lungs with air trapping seen at the of the apico-posterior
segment of the left upper lung lobe. Clear rest of both lungs.
 The central airways are patent.
 No pleural sac collections.
 Small accessory splenule noted.
OPINION
 Truncus arteriosus type I with dilated truncal root and ascending aorta , as
described.
 Cono-truncal VSD.

16. Truncus arteriosus Type II

19. Type 1

20. Type II & III

21. Aortopulmonary Window / Aortopulmonary Septal Defect/ Aortopulmonary
fenestration
 a large defect is present between the ascending aorta and the main PA.
 This condition results from failure of the spiral septum to completely
divide the embryonic truncus arteriosus.
 Not common trunk as in Truncus arteriosus.
 CHF and pulmonary hypertension appear in early infancy.
haemodynamics similar to that of a large untreated PDA but not continuous
murmur , it is systolic ejection type.
 This defect never close spontaneously,, ttt >>surgical closure.

23.  A large aorto-pulmonary window is seen, freely
connecting the ascending aorta to the main
pulmonary artery (MPA), measuring about –x- mm in
diameter.

25. POST OPERATIVE APW case
S/P surgical closure of AP window,,, developed infective endocarditis

26. POST OPERATIVE APW case
 S/P surgical closure of AP window,,, developed infective
endocarditis showing:
 Dehiscent closure patch with pseudo-aneurysmal sac formation
and reopening of the AP window.
 Supravalvular pulmonary vegetations with showering to LPA lower
lobe segmental branches that seen near totally occluded (the
lateral and anterior basal) ,, subsequent corresponding patches of
consolidations ,,, likely infected left lower lobar lung infarctions.

27. POST OPERATIVE APW case

28. POST OPERATIVE APW case

29. Hemitruncus Arteriosus/AORPA
 origin of one PA from the ascending aorta. Usually the RPA.
 Associated defects such as PDA, VSD, and TOF are occasionally present.
 Hemodynamically, one lung receives blood directly from the aorta, as in
PDA , with resulting pressure overload , and the other lung receives the
entire RV output, resulting in volume overload of that lung.
 BVH ,, cardiomegaly & increased pulmonary vascular markings.

32. Thank U
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