Cardiovascular System Embryology Questions

The entire cardiovascular system is of mesodermal origin.

Marked cyanosis is a distinct clinical sign in both tetralogy of Fallot and transposition of the
great vessels. Any congenital cardiac malformation that allows right-to-left shunting of blood is
sometimes called cyanotic heart disease. Right-to-left shunting allows poorly oxygenated blood
from the right side of the heart to mix with highly oxygenated blood on the left side of the heart.
This causes decreased oxygen tension to peripheral tissues, leading to a characteristic blue
tinge (cyanosis) and bulbous thickening of the fingers and toes (clubbing).

Because of the location of the vitelline veins and the tremendous growth of the developing
liver (hepatic diverticulum), the vitelline veins are surrounded by the liver and give rise to the
hepatic sinusoids. The umbilical veins also contribute to the hepatic sinusoidal network.

The trabeculated part of the right ventricle is derived from the primitive ventricle.

The ductus arteriosus functionally closes within 1–2 hours after birth via smooth muscle
contraction of the tunica media. Before birth, the patency of the ductus arteriosus is controlled
by the low oxygen content of the blood flowing through it, which in turn stimulates production
of prostaglandins, which cause smooth muscle to relax. After birth, the high oxygen content of
the blood due to lung ventilation inhibits production of prostaglandins, causing smooth muscle
contraction. Premature infants can be treated with prostaglandin synthesis inhibitors (such as
indomethacin) to promote closure of the ductus arteriosus.

No pulse in the femoral artery, increased blood pressure in the arteries of the upper extremity, enlarged intercostal veins, and numbness and tingling in both feet are clinical symptoms
indicative of postductal coarctation of the aorta. Because of the constriction of the aorta, the
blood supply to the lower extremity is compromised.

Partial development of the aorticopulmonary septum will cause persistent truncus
arteriosus

Tricuspid atresia involves the atrioventricular septum.

Arteries to the upper extremity are derived from posterolateral branches of the dorsal aorta.

Muscular VSD is caused by perforations in the muscular interventricular septum

The foramen primum forms between the free edge of the septum primum and the atrioventricular (AV) cushions. It is closed when the septum primum fuses with the AV cushions

Insufficient amount of AV cushion material will cause tricuspid atresia.

During embryological formation of the heart, the arterial and venous ends of the heart tube
are fixed in place. As further growth continues, the heart tube folds to the right. This greatly contributes to the ventral surface of the adult heart being comprised primarily of the right ventricle.
The definitive anatomical orientation of the adult heart within the thorax is not at all similar to
the strong image we have in our minds of the classic Valentine’s Day heart

The most common ASD is foramen secundum defect, which is caused by excessive resorption of the septum primum or the septum secundum. This results in an opening between the
atria (patent foramen ovale). Some of these defects may remain undiagnosed and may be tolerated for a long time (up to age 30 years before the person presents clinically).

The coronary sinus is derived from the sinus venosus

The superior mesenteric vein is derived from the vitelline veins.

The most common of all cardiac congenital malformations seen clinically are membranous
VSDs. The membranous interventricular septum forms by the proliferation and fusion of tissue
from three different sources: the right and left bulbar ridges and the atrioventricular (AV)
cushions. Because of this complex formation, the probability of defects is very high.

The proximal part of the right subclavian artery is derived from aortic arch 4.

Tetralogy of Fallot involves the aorticopulmonary septum.

The left recurrent laryngeal nerve recurs around the ductus arteriosus (ligamentum arteriosus in the adult). Early in embryological development, both the right and left recurrent
laryngeal nerves hook (recur) around aortic arch 6. The left aortic arch 6 persists as the ductus
arteriosus.

The renal veins are derived from the subcardinal veins.

The proximal part of the internal carotid artery is derived from aortic arch 3.

Patent ductus arteriosus (PDA) is a condition in which the ductus arteriosus, a blood vessel that allows blood to bypass the baby’s lungs before birth, fails to normally close after birth.
The ductus arteriosus is derived from the distal portion of the left sixth aortic arch.

d-Transposition involves the aorticopulmonary septum.

Patent ductus arteriosus (PDA) is the most common congenital cardiac malformation associated with rubella infection of the mother. It is unclear how the rubella virus acts to cause PDA

The gonadal arteries are derived from lateral branches of the dorsal aorta.

Patent ductus arteriosus (PDA) is very common in premature infants. Infants with birth
weight less than 1750 grams typically have a PDA during the first 24 hours postnatally. PDA is
more common in female infants than in male infants.

Failure of fusion of the tricuspid leaflets with the annulus fibrosus results in Ebstein
anomaly.

The proximal part of the aorta is derived from the truncus arteriosus.

Part of the arch of the aorta is derived from aortic arch 4.

The foramen ovale functionally closes almost immediately after birth as pressure in the right
atrium decreases and pressure in the left atrium increases, thereby pushing the septum primum
against the septum secundum. Anatomical fusion occurs much later in life; more than 25% of
the population has probe patency of the foramen ovale, in which anatomical fusion does not
occur.

Faulty fusion of the right and left bulbar ridges and AV cushions will cause membranous VSD.

The portal vein is derived from the right vitelline vein

The superior mesenteric artery is derived from ventral branches of the dorsal aorta, specifically the vitelline arteries.

Dextral looping aligns these two canals through early looping, convergence, wedging, and
repositioning. This is especially important in correcting the unusual blood flow pattern in the
primitive heart tube where venous blood flows into the left ventricle prior to the right ventricle.

The smooth part of the right ventricle, known as the conus arteriosus, is derived from the
bulbus cordis.