The truncus arteriosus is a structure that is present during embryonic development. It is an arterial trunk that originates from both ventricles of the heart that later divides into the

aorta The aorta ( ) is the main and largest artery in the human body, originating from the left ventricle of the heart and extending down to the abdomen, where it splits into two smaller arteries (the common iliac arteries). The aorta distributes ox ...

and the

pulmonary trunk A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the ''main pulmonary artery'' or ''pulmonary trunk'' from the heart, and ...

Structure

The truncus arteriosus and bulbus cordis are divided by the aorticopulmonary septum. The truncus arteriosus gives rise to the ascending

and the

. The caudal end of the bulbus cordis gives rise to the smooth parts (outflow tract) of the left and right ventricles (aortic vestibule &

conus arteriosus The infundibulum (also known as ''conus arteriosus'') is a conical pouch formed from the upper and left angle of the right ventricle in the chordate heart, from which the pulmonary trunk arises. It develops from the bulbus cordis. Typically, the i ...

respectively). The cranial end of the bulbus cordis (also known as the conus cordis) gives rise to the aorta and pulmonary trunk with the truncus arteriosus. This makes its appearance in three portions. # Two distal ridge-like thickenings project into the lumen of the tube: the truncal and bulbar ridges. These increase in size, and ultimately meet and fuse to form a septum ( aorticopulmonary septum), which takes a spiral course toward the proximal end of the truncus arteriosus. It divides the distal part of the truncus into two vessels, the

and

pulmonary artery A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the ''main pulmonary artery'' or ''pulmonary trunk'' from the heart, an ...

, which lie side by side above, but near the heart the pulmonary artery is in front of the aorta. # Four endocardial cushions appear in the proximal part of the truncus arteriosus in the region of the future

semilunar valves A heart valve is a one-way valve that allows blood to flow in one direction through the chambers of the heart. Four valves are usually present in a mammalian heart and together they determine the pathway of blood flow through the heart. A heart ...

; the manner in which these are related to the aortic septum is described below. # Two endocardial thickenings—anterior and posterior—develop in the bulbus cordis and unite to form a short septum; this joins above with the aortic septum and below with the ventricular septum. The septum grows down into the ventricle as an oblique partition, which ultimately blends with the ventricular septum in such a way as to bring the bulbus cordis into communication with the pulmonary artery, and through the latter with the sixth pair of

aortic arches The aortic arches or pharyngeal arch arteries (previously referred to as branchial arches in human embryos) are a series of six paired embryological vascular structures which give rise to the great arteries of the neck and head. They are ventral ...

; while the left ventricle is brought into continuity with the aorta, which communicates with the remaining aortic arches. File:Gray1088.png, Liver with the septum transversum. Human embryo 3 mm. long. File:Truncus arteriosus.jpg, Illustration of truncus arteriosus in a fully formed heart

Clinical significance

Failure of the truncus arteriosus to close results in the condition known as persistent truncus arteriosus, a rare

congenital heart defect A congenital heart defect (CHD), also known as a congenital heart anomaly and congenital heart disease, is a defect in the structure of the heart or great vessels that is present at birth. A congenital heart defect is classed as a cardiovascular ...

. This is often just referred to as ''truncus arteriosus''.

Echocardiography An echocardiography, echocardiogram, cardiac echo or simply an echo, is an ultrasound of the heart. It is a type of medical imaging of the heart, using standard ultrasound or Doppler ultrasound. Echocardiography has become routinely used in ...

is used to diagnose this condition. Other pathologies of the truncus arteriosus include

transposition of the great vessels Transposition of the great vessels (TGV) is a group of congenital heart defects involving an abnormal spatial arrangement of any of the great vessels: superior and/or inferior venae cavae, pulmonary artery, pulmonary veins, and aorta. Congeni ...

(arteries in this case), and

tetralogy of Fallot Tetralogy of Fallot (TOF), formerly known as Steno-Fallot tetralogy, is a congenital heart defect characterized by four specific cardiac defects. Classically, the four defects are: * pulmonary stenosis, which is narrowing of the exit from the r ...

References

External links

Truncus Arteriosus
- Stanford Children's Health *

{{DEFAULTSORT:Truncus Arteriosus (Embryology) Embryology of cardiovascular system